PDF - Gear Technology

--=-- -L
automation
Flexible, on-machine wheel dressing
Imagine getting hard finish grinding
quality at "green" shaving prices. The new
Gleasoa" 245TWG
u es infinitely
variable direct-drive
pindle
to deliver 60MJ ec, grinding
speeds
- and fully
integrates
wheel dressing and loadl unload
to cut floor-to-floor
automation
times to just. econds,
Leave it to the Gleason
worldwide
Thi
new affordable.
high-speedinspection
accurate and
machine
puts
the 245TWG to the test on a finished
46-tooth
transmission
exceptional
development
performance
team 10 put this
in an extremely
compact proven package that's remarkably
easy
to
own, operate.
and maintain.
sun gear:
Finish fast ... finish first.
Call us or visitwww ..l:leason.com
to learn more.
Gleason Cor'po,ration
I(X)OUniversity Ave., P.O. Box 22970
Rochester. NY 14607-12,82 U.S.A
Phone: 585/473-1000 fax: 585/461-4348
Web site: wwwgleasoncom E-mail: [email protected]
---
The Journal of Gear Manufacturing
MAV/JUNE lOOJ
CUTTING TOOLS ISSUE
The Two-Si:ded-Ground
Bevel Cutting Tool
26
New technology to reduce resharpening and coating costs
P'erformance' of Skiving Hobs in
Finishing lnduetinn Hardened and 'Carburized IGears
Research comparing results from different types of hobs and coatings
34
FEATURES
Char,acterization of R'e1ained Aus1enite iin
Case ICarburiized IGears ,and Iits Iinfluence 'on fatig:ue Performance'
112
The effects of high retained austenite on surface fatigue
'18
Large' Scores and Radial Cracks on Case-Hardened
Worlms
A research project exploring critical. loads on wonns
1,8
DEPARTMENTS
iPublisher's Page
Holding OIlI Breath
1
Revoilutions
48
A Giant, neared Boatlift and Gear Inspection to Detect Proces Changes
lechnicall
'9
Calendar
Don't miss these important upcoming events
111
Pmduct News
The latest products for the gear industry
24
.Advertiser Index
Use this directory to get information fast...
33
Industry INews
What's happening in the gear industry
42:
Cla·ssifieds
Services, Help Wanted, Websites and more
ICover photo, courtesy 'of
IBritish Waterways,Scotiandl
45,
Addenduml
•.
A Bicycle with R_EALGears
48'
THE
THE
MOVIE
H'AS TI'-IE OSCARS.
MlUSIIC IINDUSTIRY HAS THE
THE
US,
I
INDUSTRY
GRAMMYS.
WORL.I:) HAS T!HE 'NOBEL. PRIZE.
WEL.L.
In Oil mdopendont
WE'VE. 'GOT THIIS CHART ..
morket study Alax
CONSISTENTLY
I
Maglll·lllc',IllI(
nnd TOc( 0 W,'f,'
RANKED FIRST AND SECOND
Hl
the Iollowrnq (Oic'gOII",
Pmduct Qualify
Quality Certification (150- Type)
Low Pricle
IR,ela,tionshipwith Sales Staff
R&D Support
Technical Capability
Equipment Delivery lime
Warranty Leng,th
\Nhile it may not seem like much to look at, we're proud of what it says. And now that we are
one company, we've combined ow strengths to make sure we're on top ,again next year.
Because our goollis to continue to give you a superior product and excellent seNlce at a
reasonable price. 50 give us a call at (800)547-1527 or visit WWrN.ajaxtocco.com to get a
copy of the poll, and discuss how we can put you at tlhe top of our list.
A
ALABAMA
INDIANA
MICHIGAN
PARK
OHIO
OHIO
TEXAS
COMPANY
CANADA
CHINA
ENGLAND
JAPAN
ME)(ICO
GEAR TECHNOL,OG'Y
IEDITIORJIAIL
~blisher & EditoF·in·Chief
Michael Goldstein
Managing
Edi:tor
William R. Stott
Associate Editor Joseph I.. Hazelton
ssislant Editor Robin Wright
Editorial
Consultant
Paul R. Goldstein
TechnlcalEditurs
Robert Errichello
Don McVil1.ic
Raben E. Smith
DI!I!ThufI!l1!I!
An Director Jean Bam
~IJVERflSIN&
Advertising Monag r Patricia Flam
Advertising, Coordinator Carol Tratar
.................
CIRCUlA
.-,
flmNfslal:alt 8UCC8SS was utIizIng OU"
state-of-the-art tectnlOlogles to design the
gear tooth geometry and to manufacture
all bevel gears in the PrO &AGB for
Pratt & Whitney's PW 6000 engine.
Circulation
nn N
oordinator Carol TI"l!U!r
INTERNET
2301 Curtiss Street· Downers Grove, It 60515
Tel: (630] 96!H640 • Fax: (630] 969-0253
www.arrowg.ear.com
Web Developer DI!I! MacKenzie
Gear 1'IIdusiry Home Page™ Sales,
Putricie Flam -
powertransmiNsion.com™
ales
Michael A. Gianfrancesco
RANDALL PUBUSHINGSTA_FF
P,l'I$ld nt
VkleP,resldent
Accounting
Michael Goldstein
Ri,chard Goldstein
Dianne Borg
Phone: 847437·6604
E.mail: people@geartec/mology.col!!
Web: www.geartechnology ..com
www.powenrausmission.com
BPA
IllTEllllATIOIW.
W
VOL 20, NO.3
GEAR T,ECHNOI.OGY. Tho Journ.1
of Cu.
Monuracl'uri"l!
ilSSN 0743-6&58) " published bimn""l1y
by Randoll PubU.binl.
Inc .• 142~ Lum Avenue. P.O. Bo.
1426, Elk Grn •• Villp.J!e. 11. 60007. (847) 4J7..(i1i().1. Cover
price 55.00 U.S. P.riodlcul
po ""go paid at Arlington
Heights. IL. and .1 .ddiliolllll ",ailing office (USPS No. 749-
290). Rnndllli Publi~hIJl~ roak., .'Cry effort 10 .,."" ure thai
the P""""""
d.",ribed
on GEAR TECHNOLOGY
confann
to ~Dul]d engineenng prnctice. Ni!it.her tht autbOfR nor 'he
publisher
can be held respemsble
for lIIjurie..s snetamed
while
fo.ltov.:ing the procedure", described. Postmaster: Send
odd""" dlon.,£", '" GBAR TECHNOLOGY. The Jouma.I of
Gotat MlIi'IuI>lC!IInns. 142.~!..un1 A veuue, P.O. Bw. 1426. Elk
Grove
Vdl.S".
IlL 60007
OConlel11i
CDpynglmd
b~ RAN-
INC. 21103. No pan of 1M publJ<'aor Irl1Jn.l1lllied
In an)' fann CI" b) OIl)'
mean _. eleetren It' or meeh meal, Incillding photOl;O:pyinl.
reconhng. Of b)t 110) Inr~on
~wnge and rcmC'VOOSYr
DALL PUBLlSj{['IIO.
UDO may be ~
rem.
wnhoul
perml.!! Lon
Cooterus of .... ore subJi'Cl
4
MAY/JUNE
2003 '.' GIEAR lElCHNIUOGY
• www ..geartech.nology.c.om.
'www.powerrr,snsm'ission.com'
In wrltln,
[Q Pubb.,n.r
from
the publisher.
s lippnm>l.
,
_1.\1\ ....rr
hie a>mpreaaad
tlmea and tmproved quaIHy
with Innovative machine features.
Our CNC hobbing machines cover
the full spectrum of gears up to a
diameter of 4500 mm. Over 1,000
installations of this machine concept testify to its acceptance.
Couple all this with over 50 years
of experience and support, and
your choice for gear hobbing has
to be Llebherr,
-
SIGMAL POOL
GoaoY>;jP._oshp
oll.Joblwrr.
I(!!"II""""'O and O<t!fik""
Tho
liebherr Gear Technolog,y Co.
1465 Woodland Drive Saline, Mil 48176-1259
734.429.7225,· Fax 734.429.2294
[email protected]
I
u
Up To
MACHINE
MORE PARTS
PER HOUR
-BAR®PLUS
Dura- Bar Plus is at new engineered iron
that machines better than carbon and aUoy
steels ... and better than competitive grades of
continuous cast iron.
New & Improved Dura-BarPlus
gives you
A LOWER COSTPERPART
•••
PLUS ~ MORE PARTS PER HOUR!
Decrease cycle time.
Increase productivity!
PLUS ~ LONGER INSERT LIFE!
Reduce your downtime for
tooling changes!'
PLUS~ A DEFECT~FREE MATERIAL!
Quality guaranteed!
New Dura-Bar Plus is available in gray and ductile
iron grades and in a wide variety of sizes
and shapes. For more information, see
web site at www.dura-bar.com.
Or call
I-SOO-BAR MILL
(1-800-227-6455)
AND SAVE MONEY WITH
New Dura-.Bar Plus,
IN ENGINEERED
MEfAL TECHNOLOGY •.
Continuous Cast Iron Bar Stock
2100 West lake Shore Drive, Woodstock,
1-800-BAR-M'ILL • 815-338-7800
E-mail: sales@dura-bar;com
THE LATFST
IL 60098-691, I
•. FAX: 815-338-11549
Internet www.dura-bar;com
•
PUBUSHER'S PAGE
_
rea
As we si'9,n'aUon this, issue, the war has just begun in Iraq, The world seems to be holding its Ibrea,th.and wai,ting.
IP,riarto the war. it had seemed that the U.S..manufacturing economy had finallv bottomed out and was beginning to
sho,w signs of activity. But now,H1e world waits to see how the situation in the Middle East. will play out ,and how the
war will sUect nations that have been close allies for much 01 the last century-and
lIonger-but
now have' very diverse
viewpoints on their own best interests.
II had hoped
tOI
be able to write about the possibility o. an economic upswing, but now I just hO,pethat. the pause
caused bV the uncertainty of war won'. sap wha.ever strength and momentum (he economy was accumulating.
I'm stillihopefulthat
manufacturing activity will pick up by the end of summer. If actlivity does pick up. Gea.r Ex!po.
October 5-8 in Columbus. IOH"could be coming at ihe perfect time, Wi~b any luck. the stars will line up just right The
war will have ended, and everyone! willihave' gotten back tOImore peaceful pursuits-our
lives, our plans and rebuild-
ing our economy.
Gear Expol only comes every'two years, and recessinn ,or not, tbe technology doesn'l. 'stand still. Even if you're not in
the market to, buy any techno.logy, Gear Expo is 8, fast, easy. and inexpenslive way to see and learn about current tech·
nology. You can talk to the people' who design. build, install. service and sell the equipment. You 'can meet much of the
team 01 mos. every manufacturer. in one place. Going t,o the show can only help dev,elop new relationships,-and
sibly new business-and
pos-
facUitate' the quick gatheriing lof a wide variety of information. Those of you who do your
research now will know Ibest what to do when good fortune smilles on you.
All of us at Gesr Technolo9ywill be there" allong with a lot of other f,olks,.looking for you to visit us. St,OP by our booth
to renew your free subscription,. and you'll become eligible to win one of our wormlworm wheel clocks. We're also giving away a Grand P,r,izegear sculptllre. as we have at past shows.
So makie VOUIhotellreservstions now and stan looking over the airline schedules. Hopefully, we'U have II good summer and look 'Iorward to the fall andl Gear Expo with anticipation. At the show. you'll find solutions to increasev,our productivity and teclhnolog,y, ,and I'm sure you'lII get a wa,rm weh:ome from everyone there.
Michael G.oldstein,
IPublisher II Editor-in-Chief
www.powlrtrll,nsmission.com.
www.gearlschnology.com.
GEAR 1ECHNOLOGY
'.' MAYlJUNE
2003
7
The Broach Mlasters~,lnc,
• Gear & Spline Broaches
• Special Form Broaches
'. CNC Gear Grinding·
• Production Broaching• Blind Ho'leBroaching Specialists-
• Shank & Disk Shaper Cutters
• Generated IFormwith ,ground Fillet Radius
Go NoGo Spline Plug Gages
"Posi-Loc" Spline Arbors
Master Gears
(530) 885-1939 .. Fax (530') 885-8157" (530') 885-50'75
160'5 Industrial
Driv e, Aub'urrI', CA 9560'3
www.broachmasters.com·[email protected]
'Made In USA
REVOLUTII.DNS
Liifting 8018'tsl, IMeasulring Gears
GianI Geared WlIeellllifts.,lo,wers
B'oats lin Scotland
In pa t centuria .• the Forth & Clyde
and
nion canal were an important
comm rcialtransport corridor tretching
68 miles acres central Scotland.
Boars had to pa rhrough a series of
II locks to go between the Forth &
Clyde Canal and the higher nion Canal.
Today. boal go between tile two canal
amI pass througll only three locks. The
remaining vertical distance is covered
wuh the help oflhree large spur gears.
Those gears are part of a huge rotating boatlift at the Forth & Clyde end of
the waterway, by the town of Falkirk,
Scotland. Called The Falkid: Whee], the
boatlifl and its gears appear on Gear
1:edl1l%gy's cover.
The Falkirk WI1eel j 115~eet high,
liS feet wide and HIO feet long. It consist of two large arms that rotate around
a giant axle. Each arm has a gondola that
can c rry up to four boats at a time. The
wheel itself call lift 1.32 minion pounds,
660,000 pounds at each end.
One gear is attachedto the wheel's
taller concrete column, one is attached to
one gondola and one is attached to the
other gondola. The e teel gears are . tabililt)' gears. and each nne has 88 teeth,
Each gear consists of 22 segment plate .
Whell it plate are asseatbled, each gear
has a pitch circle diameter of 31 feet 2 inche and weighs almost.9,300 pounds,
There also are two steel idler gears,
one in each arm ..between a gondola gear
and tile column gear, Each idler gear has
2 [ rollers !hat mesh with the teeth of it
two mated
•
W.lcomt
Revolutions, "" column fir., bring. you fire Istest, most
to
up-to-datelind .1I.y-to-rud informatiDIIllbolit ""
people lind tecb-
,,111
nology of the
ind"",.,.
Revolutions welc"""" you, sub·
million.. 1'1.. " lind th,m to
G8.f Technology, P.O. Box ,.
Elk GITWI ViII"., IL ....
(M1) G1..."
Of
fax
,· ..
il
peopl ..... rttch.ology.CORI. H
you'd Ilk, .,. illiDnalltioll ..,
.. ....."
IIny of the ,ttic/. that ",.."
""., "..,,,,..,
www.gurtlchnoiogy.cGlWm.htm.
Tile wheel'saxl is supported by two
concrete columns and is driven by 10
hydraulic motors with gearboxe
that
have 1,000:.1 ratios.
Also .. the axle is upponed on bearings, with an integral I88-toolh ring gear
at the drive end. The bearings are e en
[3 feel in diameter. are Iocated in bolh
concrete column and can support more
than 4 million pounds.
The axle rotate the wheel's two
arm . As the wheel rotates, the gondola
gear and idler gea rotate around the
column gear. The gondola
tay level
becau e they're upported hy wheel that
run on circular vail in The Falkirk
Wheel' arm. The wheel .run 0.11 ealed,
double-row, pherieal roller bearings.
The Falk.irk Wheel was created all
pan of The Millennium Link, a III_ajar
project to reconnect and re tore the Forth
& Clyde and nion canals.
An importam commercial route in the
past, the canals were used less and les
with the rise of the railroad and later the
ill.llomobile.ln
1963. the British
Parliament closed the dghts to navigaIn about fi:ve minLdes. The Falkirk Wheel raises, and lowers boats almost B9feet via its geared gontion on the canals. So. the canal . weren't
dola, Ipassingl the bosts, between aqueduct ,and basin DBar Fa'ikirk" ScolJand.IFiVBI minutes r,otates 'Ih
w!Jeel'sllfms 1:80°',and is part of the wheel's rota I transit timBI as 151minute'.s. (The d'iagl\amis two small I maintained to keep' them navigable.
"Both canals were built to carry
I!lears became two :sets of roll'en Ion Ihe' a Clusl wheel.1
wWlw.power.trs'lIsmi.ssion.com.'
Wlwlw.gu,.tec#Ja,o#ogy,com'·'
C,EAR TEICHNOUJGY
'.
MAY/JUNE
2003
'9
REV,DLUTIONS,
freight," Robert Jackson says. "They fell
into disuse."
Jackson is a mechanical engineer for
British Waterway
Scotland.
British
Waterways runs the United Kingdom's
canals, Briti h Waterway
Scotland isa
part of that agency.
The canals' disu e ended in 1998,
with the start of The Millennium Link
_
The canals were made navigable again
and were reconnected by The Falsirk
Wheel, which became operational in
June 2002.
With the canal's rebirth came at new
use: leisure. Cruise boats. canoes and luxury boats for hire now ply the waterway.
"It's used commercially for people,
hut not for hauling goods," Jackson says.
Now the wheel and canals are promoting commercial development along
their course. The development include
offices, shops, pub and restaurant .
That course is new, though. With navigation right clo ed and w.ith the automobile's ri e, the canals became blocked
in more Ihan 30 places by roads buill in
the 196Os.
To reconnect the two canals, British
Waterways extended the Union Canal
almost a mile westward. lowered it
through two locks, then took it underground-below
the main Edinburgh'GLasgow railroad
and the historic
Antonine Wall, a defensive
trucmre
built by the Roman Empire.
The canal (hell emerges from its 480foot tunnel as a 99-foot-high aqueduct.
The aqueduct 'end at tile top of The
Falkirk Wheel.
Roating in the wheel's top gondola.
boats slowly wing down almost 89 feet
to. New Port Downie, the wheel's boat
basin. Boats then passlhrough a lock and
are down iJI the Fol11l & Clyde Canal,
Crowning this engineering feat is
acknowledgment of The Palkirk Wheel as
a machine that achieves the level of an.
The Royal Fine An Commis ion for
Scotland ays The FaJkirk: Wheel was "a
definite attempt to design the wheel for
tile 21 st century. This design is can idered ro be a form of contemporary sculpture ... , a truly exciting solution."
Analyze Gears Wilhout
Loc.king Out iMeasurement Vaillues
The ND430 Next Dimension®! measuring analy i sy tern from Process
Equjpmenl Co. of Tipp Cilty, OH, is
designed to measure post-heartreatment
distortion or injection molding shrinll:age.
The measuring oftware develop a
10
MAY/JUNE
2003 .' G,EAR TEICHiNOUI'GY
• Iwww.gBa"fu:hno.to9y.com
• www.p'ow,e.rt.ransmission.,r;om
_-------------11
link between loolh thickne
and
helWinvolute me urement. With standard anal)' i .method .. form deviations
are vi ible. With th Process Equipment
.analy is, Iraces are plotted to their
absolute position in pace relative to a
design tooth thickness,
This allows de igners to see thepos:ition along the face width and involute
where every measured. tooth will. be overized or undersized. With plastic and powder metal gears, ll1i data can be used to
more quickly adjust
manufacturing
parameters for making acceptable parts.
Also. if tooth thickness varies around iii
gear's circumference. designers can see
the effects on helix and involute forms.
"If you're Dilly performing conventional helix and involute measurements
{not tooth size), th effect from machine
volumetric accuracy are of le er impertance, except when you are measuring a
gear that is ala diameler or height different 'than the calibrati n artifact for that
machine" ay Mark Cow.an. director of
metrology for Proce s Equipment.
"However, when you are determining
tooth size, ab elute probe positioning in
space becomes very important, With oux
package, we have verified the accurate
probe positioning in space for !he entire
machine measuring volume by mapping
the full. '!Javel of each of
x-. '1- and 7.axes. This is unique in the industry,"
Normally a measuring probe moves
when it contacts the tooth surface. Most
ystems "lock QUI" these measurement
values.
These measurements. combined with
their volumetric mapping, ensure Ihe
machine knows the pr be' location in
pace. allowing it to accurately measure
loath thiekne .
Data can be shared with proces
equipment and .fini hing 1001. manufacturers because the program create files
of the average compared helix and invo~ute traces.
Similar y terns are made by other
companies, uch a . KJingeloberg Co. of
Saline, W. and M&M Precision Sy terns
COIp. of West Carolhon, OR
REVOtUnONS
Federal Mogul.'sinlered
processes
division bought a Ie s sophisticated version of the Process Equipment sy tern :in
2001 to inspect process changes. They
chose Proce s Equipment, partly beeau e
of il measurement certainty .of 0'.002
mm or 2 microns, with some micron
repeatability.
"The main rea on Federal, Mogul
bought the D43O' is because it was able
to in pect an unknown root area II ing a
3-Q.probe," says Jason Barnhan, pnxe .
development 'engineer at Federal Mogul.
T.II UI Whit YOI Think ...
Vilit www.,IInrcIrIoIofr.t:M1a
• Rat. thil collllll
• Rtqllllt mort infonution
• Contact the clllllpUillllHlioltttl
• M.Ie.
llIIIfIIiOl
Or ClII (.411437 ....
to 11111to _
of HI Hi-
IOrII
NACHi
'Gllobo.11 Exp,e'rtis,e
!For' Alii Ap'ipli('otions
me
w,IWIW.pOws,trtH1Smissi.on.com.
wHh cont:inued
I 8!old,erslh iPi ...
Combining over 140 years 01
process. machine. aMloal
el\Per1ence onables Nachi lMachining
TeChnology Co. to maintain InduslJ'y
leadership by iProviding;customers
with ttle "best prac1ices'
manufacturlng soluUons.
Let us help you with all 01 your
Broaching, Gear Shaving. Hobbing,
Roiling', Gear Honing, and Tool
Sharpening needs.
tJ·""
'rucJJ.
"111$111..,,PrwlGlI
Bnl£Ires
~GiA!f
$(Jini GullI
8JRI~
Pot Bn»dI
Simct
h'hI
ShIWIg CItIIn
RoIDMs
Hem
SIIl/IIIICu/lJ1"3
IkJI FooMrI /Id3
//oms
BlnmngTods
1oWtJrc.,
NACHI MACHINING TeCHNOLOGY 00.
17500 lwell)'- Th'oo Mole RoIld. Macomb.
Phone
IWIWIW•.YIIBrtechao.lo{}y.com
(~1·26J.l11DO
Fa_ (~1·263-45)1
-OlEAR TECillNllIlI.lIGY
4lIIJ4~-1103
_JlOChMTICcom
Mod'Igan
•. MAY/JUNE
20ij3
11
,
Characterization of Retained Austenite in
Case Carburized Gears and Its Influence
on Fatigue Performance
I
I
I
I
I
foua.d B. Abudaliul, J. lerry IEvans and Brian A. Shaw
Carburized helical gears with high retained austenite were
te sted for surface contact fatigue. The retained austenite before
te sting was 60% and was associated with low hardness near the
c ase's surface. However, the tested gears showed good pitting
re sistance, with fatigue strength greater than 1.380 MPa.
Detailed examination carried out on a gear that had been
te sted by contact on one flank: on each tooth in a back-to-hack
te SI revealed that about 50% of the initial retained austenite was
tr ansformed to martensite during the test. Transformation was
st ress- or strain-assisted and was limited to a thin layer of 10 urn
tilIckness or less at the surface. The increase in surface contact
fa tigue strength is attributed to the iacrea ed compressive residu a1 stress and hardness in the mechanically transformed layer.
Introduetinn
High performance gears are case hardened to increase the
hardness of the urface layer and thereby impart resistance to
su:rface contact fatigue.
!
I
I
I
I,
I:
I
Tab'le 1-Chemical
composition of the, investigated
(percenta ge by weight).
c
I
I
I
I
I
I
0.17
5i
Mn
0.5
0.008
0.0039
1.66_
0.28
p
S
II
II
I
,
I
I
I
I
Mo
Ni
Cu
0.15
0.011
0.023
0.007
10.004
Sri
AI
I
I
Gear -Property
Helix an Ie degrees)
Number of teeth
Module (mm)
'Gear ratio
Center distance (mm)
DIN quality
Base circle diameter(m-m-)-----Add en durn(mm)
-Tip
diameter (mm)
Root diameter (mm)
Base pitch error (\Jm)
12
steel
Case carburizing is extensively used for this purpose in gears
and bearings .. Carburization of the case increases the carbon
content to levels between 0.8% and l%. Also, sub equent heat
treatment is used to produce a tempered martensitic structure
with some retained austenite.
A number of standard heat treatments in gear applications
require the retained austenite to be in the range of 15-20%. On
the other hand, in aerospace applications, other standards
require the retained austenite to be reduced to less than 4% by
sub-zero cooling.
Generally. the effect of retained a:u tenite on fatigue is 110t
entirely clear. Zaccone et al. (1989) showed thai. high levels of
retained austenite increased fatigue strength in bending fangue
in the low- to medium-cycle regime but reduced fatigue
strength in the high-cycle regime.
One explanation is; Retained austenite, being . ofter than
tempered martensite, imparts a high level of fracture toughness,
which is beneficial in the low-cycle fatigue regime, where much
of the fracture life is taken up with Stage n crack growth.
Relatively little information has been published on the effect of
retained austenite on the surface contact fatigue performance of
gears.
In this paper, we present the results of back-to-back tests on
case carburized gears with high retained austenite contents.
Despite the tact that.the hardness of the material in the case was
significantly lower than in gears with normal retained austenite
contents, the pitting fatigue resistance of the high austenite
gears is good. It is believed that stress-induced transformarion
of retained austenite to martensite in a thin layer close ito the
surface is responsible for the relatively good p~tting fatigue
resistance.
Value
30
23
6.,0
1:1
160
5
-
MAY/JUNE 2003 • GEA!R UCHN,OlOGiY.
150.35
6.0
H2.0
142.7
7.0
Method and Materials
The performance of helical test gears made from low alloy
steel containing 11 high level of retained austenite in (he carburized case was investigated. The chemical composition of the
gear material prior to case carburization is given in Table I. The
dimensions of the gear are given in Table 2.
The contact fatigue SN curve for the e gears was determined
by testing in a recirculating power. back-eo-back te t rig. Gears
are considered failed when 4% of the involute flank areas contain pits or when obvious fracture took place. The SN curve is
compared with that of low alloy steel containing a normal
amount of retained austenite as shown in Figure L
www.gfJ'artechno'lo'gy.,co'm
• www.powe.rtransmission.,com
The loaded flank wru run for 32 million cycle with a contact tre . of 1,455 MPOi.The contact tress i the maximum
tre
operating inlhe area of contact between !he lnvol.llte
N<xmoI. m.:uneil
2.OOl ····
..
·0
",1
1Il6I.0I11:
High mAll!ed ll.L..rcrul~
-I
I.!!llll
flanks.
".
J1
fatigue Les!. were conducted. a gear, which was run
by contact of one flank of each lootIJ, was elected For examination. Teeth from !.he selected gear were removed, and tests
were carried out on both the run and the un-run flanks.
Microhardnes . profile on tooth C1"O section were carried
out with a 300 g load. The fIrSt indentation was taken at a distance of 50 um from the surface. Retained austenite wa .measured by X-ray diffraction with a K~ radiation beam using. AST~
Stres tech' X tre s 3000 re idual stress analyzer. Profiles up to
a depth of 50 um were made on both flank sides.
The Xstress 3000 residual stress analyzer was also used for
residual stre s measurement . Measurements were made on two
orthogonal direction, th longitudinal direction or grinding
direction and th direction tran verse 10 the grinding direction.
Note that the gear are ground in a direction parallel to Ihe axi
of the gear. The direction parallel 10 the grinding direction will
be referred (0 as the 0° directien and the direction normalto this
as the 90,° direction. Profile
of the re idual tre e in the
marten ite and the nsienite phase were obtained to a depth of
After the
i
::!;
1.600
i:l
.M
'"
1.400
!
! .200 ..I..-_'-- ........................
.o.L.._-'- .............................
I..---''-- .........................
.-.I
10'
10'
Ill"
Cycles
Figur.e 1-
tJ';tS
lIumberojcyclesforpiltillgJaliguf!
V-.
calles. gears ..(T/Je arroHl illdicate
if! I,eli·
run o.ut.)
70
...
o
SO/lm.
Vickers macrohnrdnes was used to measure the hardness of
the run and. un-run surfaces. One tooth was cut into two part .
Both parts were tested in the same manner, except thai one part
was tested after the removal of a 1I) /.LID layer by etching. Loads
of I.kg. 2.5 kg ..5 kg and 10 kg were used on each side. The penetration depth of the indentor decreases as the testing loads
decrease. Under maller loads, the te t could be confined to layers near ·10 the urfa e. In addition, microhardne
profile were
obtained in metallogmphic
sectien of the gear teeth.
In order to obtain more evidence for me changes that 'took
pia e at and near the urfcce, optical microscopy examination
was carried out on .3 mctallographic eetion of a cut tooth,
ResllUS
The retained au tenite and the microhardne s profile for the
un-run flank are shown in Figure 2 and 3. re pecth ely. These
figures show the high level of the retained austenite
ociated
with the low hardnes values. at a depth down to 0.8 mm below
the . urface,
Figure 4 hows the retained austenite profile in the run flank
side. The level. of the retained austenite was substantially
decreased at the surface and near the surface compared with the
un-run flank The change from 60% in the un-run flank to 34<Jl
in the run flank was limited to a shallow depth.
Figure- 5a and 51>·how the surface macmhardne .measurement
versus
depth of indenlation
(or lite un-etched
and the
etched pan . of the te led tooth, re pectively. The depth of
indentation was varied by changing the applied load 'between I
and 1.0kg. The hardJlle "of the run and un-run flanks wa clearWWiW.po'Wflr'rausmissio·u.com.
20 -
o
100
200
300
~oo
400
600
Depth below the surface (~ml
Il.igure 2'-.lletained IJlutenile profile
I'll
the
Ull-nm
./ltmk.
Fouad lB. Abudaia
i 0 doctora! studeru in the mechanical and systems ~llginft'rinK
II:hool.ar
rhe Unil'ersit)' of NI!....castle llpon· 7}'ne. United Kingdom. He holds a master S degree in material .cience and i~peifonning n! search 011rht
microslrue/1I1l' WId faliglll! stf"lmgth of high peifonlt(Jllt:t' 81'01" steels.
JI. Terry E.vans
is a professor of materlal s ellgilItering and acting head of lire mechanica!
and systems ,(;'1Igilleerillgschool ill the University of Newcastle upon TYII .
He Irolds
papers
C/
doctorate
ill !II!'
ill 1J1f!ll1l1urgyand has published
mort! 1111111 200
field of deformation. fatigue and fracture of materia!«.
IB'rian A .. Shaw
is l] senior materiats engineer wilh Design Unit. a pari th« mechonica; and
engineerillg schoolat University of Newcastle 111'011 TYIlt'.it selffunded agency. De igll Ullir erve indwtr)' Ihrough N! earcn and onsullane:l: mainly in the field of gearing and mechanical power transmissions.
systems
Shaw hold a doc/orale in material I'ngineerillg and has expt'ri m:e in
metallurgical characterization of gear materials and faligrle falllln!s. Also.
Ill! has cOlI.Sulll!d in areas related 10 N! sidunl SIll' ·S. fatl I~ pt'ifomwnu
and materia Iqua/il)' control il! gear steels.
WIWw.gUr,ted'Ro.lo9y.COm
• 'GIUH IEICIHNlllllOGlI' .•. MAY/JUINE 2003
13
l
700 -
1
o
1
0°°0
0-
(H)
o
0
e
..e
000
0
~
cD
0
~
I
GOG
..Q
-
I
I
,
--"-~-.l
1:
'j----.r------
600
..2
;>
:c
:c
"
I
I
-
g
I
o
~-
:>
""---f _---.-I--~-
700
..8
'D
600
,
800
800 1
.:l
...
"
400
~
]
300
Run 11m.
0- -.
00-- ....
:c
Un-run lIonk
400
i~
0
0
1,000
2llOO
30
10
3000
tndenrauon
depth (j.Lm)
Depth below 'lhe SUfl'CC (!llnl
F,igure 3-Ml'c'ro'wrdlless
F,igure Sa-Surface hard"es as a jrm,crio.n' o.f illdtmtatUJII depth,
before Imrjace .la}'er ~el1lo."al
profile for the UIl-rUlIflalllr..
Wr' ~----~----~----~----~----~----~
\
I
gOO I
I
~'O"-_-o.
's
~-~
-"-
:
40
!!
..8
...
,
700
~
"I!I_ ...
I
I
1
1
-~_~
.............
:
e
...
-0... ............_ ...
... - .......
i!i
~
..........
,600
.2
a:>
""'!J
:J:
n
.500
It- - .... Ruo
lIank
Un-run nank
0--.
~
:!::
10 ........-'u
-........
I.
-'--
100
2l1O
-'-- __
-'-- __
-'--
400
.L.J
SOO
0
600
5
10
De,plh 'below the urface Oun)
Figure 4--Re.tainedauslellite
Figr,,-e Sb-Sllr/aCe hardmu,s a ,Q function.
sho.wing the effect of surface layer removal;
in ,tI,e nm fl~',lk after 3.2 nlillioll
cy.cles at a surjace contact s~ess of
1,455 MPa.
Iy different for the un-etched specimen (Fig. 5a). However, after
etching
were
10
1J.m, the
hardness
values of the run and un-run flanks
de,pths were al
at shallow
0
noticed
for residual
tress measurements.
Residual stres profiles were measured in
the run andun-run flanks in both the martensite and the retained
austenite. In addition. residual stresses were measured in the 0°
and
90°
91)° directions,
Residual
stresses
in
phase in
an-run flank exhibited
phase on both flanks and
6c and 6£1.
the OQ direction, the run flank:
stress at the surface" whereas
only a small compressive
0
in the 90 direction.
-500
there was little difference
the un-run flank
(Fig. 6d).
near the run and un-run ides of the same
in Figure
7aand
7b, reo pectiveIy. The
micro tructure wa t.ypical of material with large au tenue grain
size. Plates of marten
ite were clearly visible
ite matrix. A higher marten ite plate content
the surface of [he run flank. This supports
during
or strain-assisted
stress.
In
A greater difference
(Fig. 6c) ..However,
MA'I'/J'UNEZ003.
a maller difference
GUR IECHNO''LOGY.
austen-
the idea thai. stre
transformation
-
occurred
urface contact.
Hiscussion
The high retained au tenite content in the case of the carburized gear teeth produces a relatively low hardness down to a
depth of 0.5 mm (Figs. 2 and 3). Despite the substandard hardness level, the gears with high retained austenue
have good pit-
108 cycle . Certainly,
bowed a resid-
tress di tributions
in the austenitie
the
was evident. near
the
between the run and uri-run flanks.
in the residual
martensite
within
ting fatigue re istance, with strength greater than 1,380 MPa at
MFa. At depths greater than 10 urn,
to a greater depth was observed
direction
are shown
,0/ illde1ltaIWn depth,
the
tre s of just less than -400 MFa while 'the run flank showed
a tress just greater !han
14
the
the austenite
are shown i.n'F.igures
the martensite
martensite
profiles:in
respectively.
hawed a large compressive
ual
Microstructures
phase for the run and un-run flanks on the 0° and the
martensite
In
the 90° direction
assisted
d:irections. The results are shown in Figures 6a-6d.
Figures 6a and 6b compare the residual stres
directions
in
tooth
en iDly the same (Fig. 5b).
Changes
20
15
Indentation depth (11m)
down
phase in the 0°
was observed
tempered
if fully martensitic
specimens
to produce a similar low hardne
were over-
,Olle would expect
to ee a ·gnifican.IJy reduced pitting fatigue strength.
The evidence from hardness tests, X-ray diffraction
allographic
examination
suggests
ance i .due to either stress- or strain-induced
formation
and mel-
that the good fatigue
in a thin layer near the surface
flanks.
www.gea,te'cIHlo.fogy ..com • www.powflflransmission.com
resist-
martensitetransoflhe
run involute
·F,ig.ul'f!
6-ReS"idualstress
distribution in the
marlf!flile
and
Qustenite phases.
200
J
i
e
~
C
0
....
L
r ....
- .........
I
~
11'-_ ....
,
,,
-200
I
,
I
--100
g,:
-600
i.
--_·------11
f. -:-"-1--':-':;
zi: --- ---"1
1
i
-200
"
-fj
-'100
/,
-
//
'8
,,
,,
I
'C
I.,-
III
:g..
,
rI "
I
r
•
O!:
-..a Run:l1&nk
-8 Ua-lUllliUok
-tal
"--1;1 Rlln Ow
"--9
0
20
n·"", flull
80
Depth below 'lhe surface (!lm)
Depth below 1M wfllCe (JilII)
Figur:e 6B-M'artensite phase. 90° direction'
200 I
200
~
;
g
,J".- '---1---.-.- -•... '---1!
,,
"
~
..,
-
f
'~
011
:'11
-
II
-600
1
... -.
.---e
Un-run nau:
Run fimk
-~J
o
i:F-.
I!!!·--
10
20
30
4U
-0
n-nml1&nli.
R"" nom.
I
50
7Q
80
Depth below the surface (!lml
.F(gUTf
There is, dear evidence iliat urface contact in the back-toback 'tests, reduces the retained au I.enite content at the . urface
by OJ factor of two. In the un-run flanks, the retained! all tenite
conteru i of the order of 5.5-63% (Fig. 2). After cycling urface
contact in UiJeback-to-beck tests. lite retained! all lerute content
at the surface was found to be reduced to me level, of 30-35%
(Fig 4)..
The thin layer of contact-reduced retained all te'nite is of
the order of 1,0111m. This conclu ion is supported by the Uliface Ilardne _ results in Figure: Sa and 50 .. In Figure Sa, the
un-run surface shows a lower hardness than the run flank: at
penetration depths between 12 and ]8 microns, Also in Figure
Sa, at greater penetratica depth. the hardnc
value convel\ge. At the mane t penetratinn depth of 7 J,lm. me hardnes
value for the run and un-run flank again converge .. It is
believed that. at the man indentor depth. the influence of
train hardening Irom grinding during manufacture is dominant. i.e, both run and un-run involute flanks were ground in
Ithe final stage of manufacture.
After the 10 I1murface layer was removed by etchlng, the
hardnes res of run and un-run flank were en ibly identical at
all indentor penetration depth. in the range 7-25 11m (Fig. 5b).
This latter evidence
upparlsthe li.dea that igaiflcant hardne
IWlww.po':wer,traasmi.ssion.c,o.m
,6D-Auslmile phtue. 900 directioll
increases occur as a result of surface contact, but only to a depth
of 1.0 J,lm or les .. We note, however. that the relation between
hardness and depth of indentation (Fig. Sa) does not gilve 3.
direct relation between the measured hardness and the hardness
gradient in the material urface layers. because the harder layer
near the surface coruinues to influence measured hardness al
penetration depths greaterthan the hardness of the layer.
The mechanism of stress- .or strain-induced
austenite to
martensite transformation 'II lhegear
urface remains to be
understood in detaiL It is known that the transformation of
retained austenite can be nucleated by externally imposed stress
(or elastic strain) acting alone and by plastic strain (Olson.
1982). Maxwell et aJ. (1974) reported a. different morphology
for marten iteproduced by the aid of Ire and plastic train, In
addition, stres -3 si led and plastic- train-a si ted martensite
formation operate over different temperature ranges. Stressassisted martensite transformation occurs predominantly below
a characteristic
temperature M/ w'hilc plasnc-strain-assisted
martensite occurs between M/' anda higher temperature Md' At
'temperatures above Md' neither stress-assisted nor strain-assisted transformation of retained austenite OCCIl'rS. Neu and
Sehitogh; (1991) found for carburized 4320 steel that stressinduced! tran. formation occurred between 2rC and 60°C.
.' Iwww.gfllYleclJnotogy.com
• IGEARfECIiNOLOG't .' MAV/J'lJNE
2,003115,
Condu :ions
Gear materials made from steels with high levels ofretalned
austenite showed high fatigue resistance and good performance,
Stress-assisted rnartensitic transformation occurred under
the influence of the contact stre se .
Transformation was confined. to a thin layer of about ]Q (m
in depth.
High compressive stresses are SCI up in the transformed layer
due to constraint imposed by the austenite matrix and the core
material,
Martensitictransformation
caused Ihe urface hardness tobe
increa ed.
Changes in micro tructure, residual tresses and hardne
were confined to a thin layer ofabout 10 11m in depth, The e are
beneficial changes from the surface fatigue point of view and
resulted in improved performance. 0
Stress-assisted
martenstre
(Run flank)
This paper was Ipres'ented at the ZD1IlI.ASM Heae Treating Society
Conference', Ihel'dOcl9-112~ZOOO.in ;St. Louis. MO. ,ruso', .be paper
was published bV ASMI Iln1emae,ionall in the conference'si pro·
ceedings,
Retained
austenite
(Un-run flank)
Figure
7-Microstructure
i" the
rUII
and
,lm-rollj1a.nks.
A further
observation is that compressive axial stress or
hydrostatic stress suppresses the transformation. while axial or
hydrostatic tension favor. it. Thus. little train-assisted transformation is observed when We pia lie deformation OCClJrs with a
superimposed hydrostatic pressure, while the greatest amount
of transformation
occurred under axial tension (Neu and
Sehitoglu, 1992), These observations are pertinent to 'the present results because the stress field produced by surface contact
of the involute flank: i predominantly compressive.
The Von Mises stre es are less than the yield trength of the
material for ideally smooth urfaces, Thu , any plastic deformation in the involute flanks must occur at the cale of the surface asperities, Even 0, the uperimposed hydrostatic tre is
predominantly compre sive, thereby acting to oppose straininduced martensite transformation,
Surface 'contact had an effect all residual stresses onJy near the
mace, As shownin Figure 6a. urface contact produced a significant surface re idual compre i.v e stress injhe OD direction. This
is consi tent with tre s- or sirain-illlduoed martensite transformation. which is expected to produce residual compressive stress
because of the associated 4g,: volume increase, 011 the other hand,
it is believed that the surface residual stress is complic-ated by the
treatment prior to testing, The last operation is surface grinding.
and the different residual tres es in the 0° and the 90° directions
in the lin-run flanks (Figs. 6a and 6b) aretypical of near-surface
residual sire se pKlduced bYE!grinding operation.
116 MAYf.JUNE
2003, • !GEA'R lEC!ItNllIllOG¥
•
Refereaee
I~.Maxwell. P.e., A. Goldberg and J,e. Shyne. "Stress-As .i ted
and. Strain-Induced
Martensite
in Fe-Ni.-C Alloys."
Metallw-gical Transaction, Vol. 5, 1974, pp.. U05-131 S.
2. Neu, R.W. and H. Sehitoglu, "Transformation of Retained
Austenite
in Carburized
432() Steel," Metallurgical
Transaction; Vol. 22A .. 1991. pp. 1491-1500,
3, Neu, RW. and H. Sehitoglu. "Stress-Induced Transformation
in a Carburized St,ecl-Experiment
and Analysis," Acta
Melallurgica Et Materialia, Vol. 40. No., 9. pp, 2257-2268.
1992.
4. Olsen, G.B., and M. Cohen. "A Mechanism for the StrainInduced Nucleation of Martensitic Transformation," Ioumal of
Less Common Metals. Vol. 28, pp.107-11.8, 1972..
5. Zaccone. M.A.. 1.8. Kelley and G. Krauss .."Strain Hardening
and Fatigue of Simulated Case MicrostructllIe in Carburized
Steel," Carburizillg: Processing and Performance. ASM
tnsenuuional. Lakewood. Colorado, July 12-14, 1.989,
Tell Us What You Think ...
Visit www.geartechnology.comto
• Rate this article
• Request more information
• Contact the authors or organization mentioned
• Make a suggestion
Or call 18411431-6604 to talk to one 01our editors!
www ..goBrt.eclmology.com
.. IWWW.pOwlfI18nsmis.sion,com
1
11
TECHNICAL ICAIIJEND'.AR:
_
May
20-22-f'undameo&.als
or Parallel
Ax! Gear
Manufacturing..
Pheasant RUIl Rc~oJ1. St. Charles. 1 , This
erninar, with a limited class size of 35, focuses on gear nomenclature. automation ystems, basic gear mathematics, bobbing,
skiving, fixruring and blanks. as well as other topics. $750,
including meals, For more information,
contact Koepfer
America LL.C. at (847) 931-4121 or on the Internet al
www.koepJeramenca.com.
June 8-12-100.3 InU:~rnational 'Conference on Powder
Metallurgy &I ParliculaCe Materials. Mandalay Bay Re on &
Casino. Las Vegas, NV. PM2JEc-2003 will offer an exten ive
technical program mat include
eminar for delegate in the
powder metallurgy. powder injection molding and particulate
material industries. Costs range from $40-$1.175. depending
on the package selected, For more information" contact the
Metal Powder [ndlJ. tries Federation by telephone at (609) 4527700 or by e-mail at in/o@mpijorg.
Jun 9-l2,-:Basic GeM Fundamentals.
Gleason Corp", Loves
Park. Il., Thi four-da.yprogram con isis of lecture given by engineering. production and inspection staff members to provide an
understanding of gear geometry. nomenclature. manufacturing and
inspection to people new to the field. Attendees are taken n a tour
of Gleason's facility and given demonstrations. Contents of the
seminars include gear history, type and ratios. involute gear
geometry, gear tooth systems and gear cutting methods. 895
includes a handbook. c1as material. lunche and ne group dinner. For more information, contact Gleason by telephone at (815)
877-8900 or on the Internet ,at wWl4~gleason.com.
I1Ilo,ving precision
June 9-.l3-A.GMA. .:2003 Da it Cenrse,
Daley College.
Chicago, [L. Offers classroom and hands-on training in gearing
and nomenclature. principles of inspection. gear manufacturing
methods, and hobbing and haping.650
for AGMA member,
$775 for non-members.
.or more information, contact AGMA
by telephone
at (703) 684-02U or bye-mail
at
fentress @agm~t.org.
JUDe .23-2S-A.GMA's Regional Gear Manufactu.ring
TeChnology Course. Star-SU, Hoffman Estates, Il; $750 per
attendee. Three-day course pre ented by the Gear Consulting
Group LLC. For more infermation, call (866) 202-1699 or end
!IJ message 'to [email protected].
Ten Us What You Think ...
VisitllllWW.,,,nschnDlogy.com to
• Rate this column
• Request more infonnation
• Contact the organizations mentiOfled
• Make. suggestiOfl
Or call (141) 431-&604 to IIlk to one of our editors!
IWIWW.,f10'W'''''''rJsmi.ssion.co,m.,
To miniGears, preciSJOil Is the anention given 10 deveJoptng gears
designed for the specific needs of e'lllP1 application. It IS the reliability of
iii sole supplier. y"ho is able 10 offer a vaIlety of different soiyllOllS: bevel.
helical and spur gears. all 01 whICh are avaJlable H1 CU1metal, powder
metal or plastic. in add Ilion. complete 1ransmISSlOl"lS and motors are
also offered. II IS 'the flexlbi ty 01 a company that is accustomed 10
dealing with internal1011ally rel""1O'M'l6dcustomers. n IS a Quality based OIl
more and more restrictive parameters. granbng. miniGears world-WIde
competitiveness. PrecIsion is everylh ng to mlniGears.
mlrdCh_dIortft." am.rIca
2505 lnIernatlOIlII ~ay
Virginia Beacn VA 23452 • USA
ph. (757) 627-4554 lal'l (757) 627..()944
e-maIl mg.J.!saGm1n1gears eorn
InterneL _
nlInlgearscom
IWiww.gUdfU;II'O,olog,.c,om
~ GEAR, TECIII'NDL10'GY'· MAY/JUNE
2003
11'
Large Scores and Radial Cracks on
'Case-Hardened Worms
Wolfgang Predki, 'Friedr,ich Jarchow, Ralf iDinter and AI!exander Rhode
the worm wheel made of bronze, This
material has a lower strength than the
worm made of steel. Critical loads are
reached if pitting. sliding wear, tooth
breakage, scuffing or high oil temperatures occur. However, in the last couple
of years, defects such as radial cracks or
large scores have increased on the casehardened worm surface. These detects
can cause an increased wear on the wonn
wheel, which can lead to a premature loss
of drive. This report shows a way to
determine the maximum permissible load
thai.leads to these defects. as well as te ting new methods which increase the load
carrying capacity.
Test Conditions
The test runs to examine score marks
and cracks on hardened worm flanks
were executed separately on two electrically strutted test stands. The mating
materials are case-hardened worms made
of 16MnCr5 steel and worm wheels
F,ig. I-Test stand for scori,lgdamage,
made of GZ-CuSn12Ni bronze. 'tests for
center distance a = 1(/0 mill.
scoring were executed with gear sets
with a oenter distance 0'1' a = 100 rnm, a
gear ratio of i= 41: 2, a worm shaft
arranged below the worm gear am:! splash
lubrication ..Figure 1 shows the test stand
that was employed for scoring tests.
After assembly and adjustment of the
contact pattern, the worm gear sets were
loaded immediately with the entire
F.ig. 2-Test stand Jar crackiJlgda11lag,e, torque and run for 336 hours, without any
center dislafll:e a ::::250 111111.
running-in process. The rotational speeds
of the tested WOlTIlS were:
nl = 400,: 650; 1;030 and 1,470 lImin.
The torque varied from l.0 to 1.75
times the nominal torque that is given by
the gear manufacturer (Ref. 7). Cracks 011
the worm flanks were tested on larger
gear sets with a center distance of a ==
250 rnrn, a gear ratio of i ""39:2, a WOIDl
shaft arranged above tbe worm gear and
a combined splash/circulating lubrication
Fig. 3-Large score marks on ,a casewith an external oil cooling system. That
hardened Klorm.
Abstract
In the last couple of years, many
research projects dealt with the determination of load limits of cylindrical worm
gears. These projects primarily focused
on the load capacity of the worm wheel,
whereas the worm was neglected. This
contribution
present
investigations
regarding damages such as large scores
and cracks on the flanks of case-hardened worms.
Introductlnn
The load-carrying capacity of cylindrical worm gears is generally limited by
18:
MAY/JUNE 2003 -GEAR lECIHNI(I'LOGY •
www.geartechdology.com
test stand is shown in Figure 2.
The testing period is limited to a maximum of 1,650 hours. The rotational
speeds are 1,500 and 2,200 Ilmin.
During the tests, the applied torque
exceeds the nominal torque 1.75 and 2.00
times. The employed lubricant for each
case is a poly glycol called FVA-reference-oil PG4 (Ref. 4) with additive combination LPI.655.
Test Results: Scoring
Figure 3 illustrates a worm. gear damaged by score marks, Compared to new,
never-run worms, the flanks show a
rough surface within the area of contact.
These score marks are transferred during
operation to the flanks of the worm
wheel and cause excessively increased
wear that often leads to, a premature failure of the entire gear set.
In order to register the amount of
scoring damage, measurements of the
surface are carried out in the complete
mating area of the wonn shaft. The measurements are taken in the radial direction,
perpendicular 10 tile expected score
marks (Fig ..4).
In the radial direction, parts of the
teeth are separated intQo fOQoI, center and
tip. Tests with a low rotational speed of
nl "" 400 lImill and J.25 times the nominal torque show the largest scoring damage. The distribution of the measured
arithmetic mean roughness Ra after testing is given with Figure 5. The measured
values for each position from the beginningto the end of the contact area are
plotted. The roughness of the flanks ill
the initial state is the standard of comparison ..New worms have an average arithmetic mean roughness of R(J = 0.4 !-lm.
The distribution shown is typical for
worms that are damaged by score marks.
The greatest roughnes alway occurs at
the end of the contact area.close to the tip
of the tooth. Towards the beginning of
1
• www.puwertransmiss;oll.com
tlIe mating area, the values of the roughne s decrease. Similar tendencle can be
OD erved in the center of th teeth. bul
the maximum values are lower. In the
area of the foot, the measured value.
catter; but they reach comparatively
large value .
Comparative measurement
of the
worm shaft. and the worm wheel how a
good representation IOf the coring damage of \he worm flank DYmeasurement
at the whee! tooth center. At this poirn, 1
the malle 1 lubricant film thickness and 1
the smallest relative motions directed:
toward the height of the tooth occur during operation between worm and wheel. :[
Score marks of the worm are reflected ~
011[0
the center of the wheel teeth. ,~
Therefore, score marksat the wheel are ~
uitable for the qualitative de cription of ~
the coring damage at the worm flanks. [
Figure 6 shows the measured arithmetic 1
mean roughne s at the wheel after sepa- ~
role test NOS with different load . All ~
tests were executed with case-hardened 1
worms made w.ith 16Mn r5 steel and ~
wheels made of GZ·CuSnl2Ni bronze.
l
The te t result show Eli ignificaJlt!
dependence
on rotational
speed and
torque. The amount of scoring damage j
increases with an increase in thetorque
applied and decreases with the mtatiomlli 1
peed of the worm hafl (Fig. 6). On the j
one hand, increased load lead to an
increased coring damage. On the other ~
hand. an increased rotational peed lead '
'10 Ie
coring. Tile . tronge t coring
damage can be observed at rotational
peed. of III = 400 ]lmin. At rotational
-peeds of more than n, = ]'030 l/min, no
core marks result, even in the case of
high overloads. The roughness of tlle
flanks after testing is almost the same a
in the beginning, The arithmetic mean ~
roughness represents the amount of scor- 1
ing damage.
A regre ion analysi quantifie the 1
dependence of the expected arithmetic ~
mean roughne
on the worm wheel on ~
differenl load a rotational
peed n I' :
torque T2 and oil 'Sump 'lelIl:pera~ure t}s by
four coefficients Q14'
j
i
l
i
l
l
l
R.... ., al + (112 -
II)··
11,
+ a4··"
) •
Tz ~ 0 IlJTI (W)
!
Figure 7 shows lite expected
arim-
! ...--------------..,
metic fOughllessRo..R after application of:
Equation
I. A data map show the ~
expeeted : coring damage for the examined material-lebricam
combination
depending
Oil torque
and rotational
peed.
A observed during IhetesLs,
the
roughness increases with increasing load
and decreasing rotational speed. Mea- 1 I
urement during the te ting reveal an . ,
www.pow.erIr8nsmfss;olJ'.com.
4
=
increased wear for Ra.R
1-2 um, and
excessively increased wear if greater
roughne s applies. In some cases, the
mea ured wear exceed the value precalculated by Dm 3996 (Ret. 3) I.Ipto 20 .
time . For this reason, an arithmetic
mean roughness above R,. = 2 um has to
be particularly regarded as critical. For
operation with constant torqu.e directly
after gear set assembly, the loads should
be cho en in a way that the expected
arithmetic mean roughness lays below I
um, :in order to avoid damaging score
marks.
The presented approach can only be
used to predict the behavior of the tested
malerialJlubricant
combination and the
given geometry of the gearsei, A prediction for operating points which are not
represented byjhe examined range of
torque and rotational peed is Illghly
uncertain and not verified by practical
inve tigations, A tran fer of the results to
djfferent. size and another tooth geomeIII}' just by conversien of the dependent
factors 'II' T2, Os to other factors such as
sliiling velocity Vgm and meat! contact
. Ire 0H", Jack of lest. re ults for these
coadinon .
Method to Avoid Seere Marks
Scoring on the worm flanks can be
avoided by the use of PVD-coated
worms such as tho e coated with
BAUNIT C (Ref. 1) or !he use of the
additive GH6. Compared to the basic test
runs,even higher torque can be applied.
No score marks appear during these tests.
on erted oil change after 48 and 144
hou.rshelp to reduce the scoring damage,
However. scoring cannot be avoided
completely by this particular means.
Compared to the basic gear set , no
www ..gesrtfu:lmoio(1y
[!] Roughness
Measuring Length
8
1'--__
-
----_-'
Fig..4--Posi/jon~ wbere measurement of
tIle surface are tak,m to .repr-esentscoring
damage.
Prof. Dr.-Ing. Wolfgang IPredkii
is Ihf' head OIl/If' chair of ml!c/wnical components. indu tria! and aU/olllo,il!C' power ,Iransmission 01 R!lltr Uni"f'rsily ..Iocaled ,'11 Bochum,
Germany. The chair's research focuses all wear
optimiunion of I!'orm gears, plastic ana sintered
'~orm f(l'ars and bl1Ol!~eoptimization •
Prof. em, Dr;-!Ing. IFriedrich J'an:'how
is lireformer head of rht' chair of mechanical
C:OflJt'()nem.I'.industrial altd automotive power
transmission elf Ruh» University.
.
Dr,-Ing'. Ralf IDinter
is employed at Winergy II G. a leading pTrJloitltr
of drive systems for wind turbines, located ill
VOl!rtielFrjl'driclLgeld.Germany. Willergy AG is
II subsidiary of A.. Friedt: Flmdu
GmbH. based
in BCI<;Jwlr. Germany,
Dipl ..·I'ng', AI!exander Rhode
is a research assistant ar the c:iJlliroflfJl'c:himj·
indus/rial and automotive
po ....er transmission fIf Ruhr Univer. iry. Hi
work focuses on the inve ,jg.IJJionof large score
OIl .. -orms.
cal components.
..com • IGEAIRnCHNOLOGY
• MAV/JUNIE 2003. 19
up 'the results of everai tests, The testing
period
by thelengtll
of
indicates
is represented
bar. Different
each
hatching
several defects on the worm flanks, The
e
112.0
employed
WOI'm
10 ..0
hardening
processes
materials
a we:1I as the
are given with this
figure.
8.0
The nominal torque must be exceeded
:::Ii.
by far to produce cracks. High load lead
to heavy
pitting
excessi ve
and,
in some
cases,
wear on the worm wheel . The
cracks on the worm flanks always occur
at the end of the mating area and
radial alignment.
how a
There are two di fferenl
areas for the origin of the cracks and their
direction of growth. On the one hand,
cracks
start at the inner delimitation
the contact
Roughness Measuring Length
NIEW
towards
the tip of the worm tooth (Fig.
9). On the other hand, crack
.Fig. 5-Arilllmetic mean roughness after testing (336.hOllrS).
TIl.....16MnCrS case-b.ordened/GZ-CuSn12Ni..
11/=400
= 1.2S'
11min, T2
-
tip and grow toward
the tooth (Fig. 10) .
located
within
geous
lubrication
an area
observed
the
in these areas.
examinations (Ref. 2, 6)
how the smallest lubricant film thickness at the inner delimitation of the worm
3.0
mating area. Compared
2.5
to other areas on
the flank, higher friction factors apply lor
this region. The combination
2.0
400
1.5
of high fric-
lion factor and the existing
particularly
towards
peed
lead,
the end of the mat-
ing area, to high temperatures
I
on the
0...5
flank.
0 ..0
Cracks that start at the tip, of a worm
tooth can be observed if large pitied areas
1.25
T'2l
are
1.5
r;
1'.75
with center distances
application
High sliding speeds and incornplete
polished
or
crowned
worms made of 1.6MnCr5 case-hardened
above a::: 400 mm.
tart-
ing contact patterns lead to high specific
steel. Spelling can be observed within the
loads on the tooth flanks of the e gear
nitrided fringe of gas nitrided worms.
drives. For economical
Test. ResuWfs: ,Cracking
Radial
cracks on the flanks of caseworms can be encountered
gear sets with center distances
above
200 mm, but. they predominantly
MAV/JUNE
on
Ci :::
occur
2003: • G'EAR IEC,HINOUIGY
on
the
wheel
teeth
and
wear commence . The tooth
'face tip of the worm "digs" into the feot
of the wheel tooth. The development of a
sufficient lubricating film in this area i
improvement should be expected bythe
of
located
increased
.F!·g.6--ATitJlmetic mean .~ol~glmessof the wl,ee' after.336 hours.
201
After
of bronze can be
Theoretical
3.5
hardened
cracks is
of disadvanta-
conditions.
tests, a local transfer
1..0
tart at the
For both cases, the origin ofthe
4.0
of
field with a growth direction
bench te ts, gear
by the sharp-edged
tip of the
worm tooth and the prevailing
conditions
restrained
of motion.
A theoretical
analysis
of the mating
process show a contact or wear between
drives of the size a ::: 250 mm were
the tip of the worm tooth and the foot of
examined,
the wheel tooth at the end of the worm
These
with overloads,
drives
were
charged
up to twice the nominal
torque.
Figure 8 shows a. bar chart that sums
mating
area, which eorre pond
to the
test results.
As
metallogrsphic
• www.ge.ar •• choology.com.wwlw.powertrlJ.osmissio.o·.com
examination
show, the flanks of the worm were
stressed by very high temperatures within the mating area. The fringe texture i.
thermally influenced. Even rehardening
of the Hank urfaces occurred. Rehardening require temperatures above the
au tenite temperature of at lea t a'CI ..
723°C'.
lruemal stress analyses reveal, that the
loads applied to the wonn flanks lead! to
high tensional internal stresses within the
fringe. A new worm shows compressive
internal stre se: within the same areas,
The change in the stale of iaiemal
stresses by high surface temperatures is
shown in igllre U. In this example.
'there is no internal stress at the beginning. A short application of a temperature
field to the surface of a part causes compre ive tre ses within areas cia e to the
urface becau e a free, temperaturecaused exten ion i prevented by tile orrounding colder areas. An increase of the
temperature causes higher compressive
internal stre es, If these stresse reach
the hot-strain limit. pennanem 'trains
'OCCIIf. The value of the hot strain-limit
depends
on the temperature.
After
removal. of the thermal
Ire , the
deformed area cool down and the SIXain .
are . aved as lensional internal tres e .
Hertzian contact stresses and tangential
loads caused by friction promote this
effect If the local trength of the material is exceeded by tensional internal
stre eS,Lhe growth of a cruck commences.
Test 'Conclusion
The nominal torque ha to be exceeded by far to produce cracks on, the worm
flank.
For thi reason, Lhese defects
sheuld not be expected under normal
working condition
with worm gear
dri ....e of the tested size. The defects are
cau ed by high thermal loads in combination with a. local transfer of bronze, In
particular. cracks occur in combination
with heavily pitied worm wheels.
Tha.t is another reason wily !pilting
should be avoided. Gas mtridcd worms
tend to . pan within the nitrided layer.
In order '10 reduce 'the risk of cracks on
case-hardened worms, the specific load
1900
1800
1700
1600
1500
1400
1300
1200
1100
1000
900
BOO
700
600
SOO
-
C
:5
o
C')
0
IQ
10
o
s
.-
0
0
.-
0'
0
0
0
I')
II)
-
0
0
CD
'0
0
...
.....
,0
'0
1"1
N
0
0
N
400
300
200
100
s..... s
101
'0
0'
10
N
IN
N
Rotational worm speedi n, [min"]
Fig .. 7-E timatedscoring damage,. calculated b>,equation .1. GeaHet: a = 100 mm, ;
20.5, 161~1nCr5ehIGZ·CuSIl12
it operoJion will. "omillat wad; flO' running-in',. nominal
torque
Tl•V taken/rom
mauuJactur;er data (Ref,
=
n
T1
1500mn
.. 8O'C n ..
T .. 81501
10000Nm
T2
1500 min
13
tOOOO'Nm
2200
22tIO
rrun
I11III
'IOOOONm
T7
16MnCl'5 case-hardened + MllkIed
T8
HSMnCr5 ,case-hardened
=======:::....-..:....
'* n:iIride<I
nitride<I
34CtNiMc8
T9
1110
o
500
3OCrMoV9
1000 '
n"
+ polished
regrinded
1500
2200 mIIiI
1 .. 10000' Nm
n"
2200 rrIn
1 .. 10000' Nrn
20001
l'esthlgl period [h]
S _1m;
Pit1!1l11
Fig. 8-Tes, results cracking .. Wheel is GZ-C"S,112Wi; lrtbricant: FVA·PG4 '" LPl655
on the flanks. lIould be reduced and me
loud-capacily again I cuffing should! be
increased. Ia general, this can be reached
by !he following means:
• Largest. possible starting contact pattern;
• Fasr running-m by use of a bronze
with low 'Iccnglh in combination with a
mineral oil. subsequent oil change and
use of a more efficient polyglycol:
., Use of a lubricant with high loadapacity against scuffing in order to pre-
WWW.p'ow,flfflansmission,com.
www..gearteclmology
..com.
vent local transfer of bronze:
• Prevention of pitting on th wonn
wheel (for precalculatioa,
ee Ref. 5).
Conh .. ions
This research project explores the
criticalloads of hardened worms that are
combined with wheels made of bronze,
Two different types IOf defects, large
scores and radial cracks. are examined
eparately .
A map for score damage can be created. It show that all increased amount of
GEAIR TlEC.HNOLOG,y
• MAY/JUNiE
2003
21
This paper was printedw:ilh the permissian of the, publiisher'rom
VOl·
Gesellschaft Entwicklung,IKonstruktiolJ.
Vertrieb '(iEd.I,; International' Conference
on G'ears. Vot 1. VDI-Barichts
1665.
Dilsse'ldorf: VDI-Verl.ag
2002, Ipp.
435-449!.
Fig. 9-Worm t~ken from test T3. Origin,
,o/the crack,alll,e imlerdelimitaliOll o/the
eontac: field
(cracks
redrawn for bet1,er
illustraJion).,
Fig. 1000Worm takenfllom ret Tl. Origin
o/,tlle crack at Ihe tip o/th'l! tooth,.
Rd renees
1 .Balzers AU: "Fi rmenschrift" • Del' Weg lU
:,u\·er.liissigeren Bauteilen, Liechtenstein,
1.993.
2. Bouche, B.: Relbungsl.ahlen
lion
Schneckengetrieben
Temperature
J;ensJon
»J
!~
t
...
"10·
•
Compression
im
Mischreibl.lllgsgebiet. Dissertation RuhrUniversitiil Boch-um, 1991.
3. DlN·Entwurf
3996: Tragfiilligkeitsberechullg
von
Zyi'illder-Sclmeckengetrieben mit Achsenwinkel ;E;90°. Entwurf
1195•
4. fV A-Porschungsheft 316: Synthetische
Re}erellzole,
/ar
Datensal1lmlung
Syntheseole,. 1990.
5. FVA-Al'beilsblatt
zum Forschungsvorhaben
Nr.
1.2f1V:
Versuche
,zUI"
GrfJbchentr:agflihigkeil
,.",....
Compression
Fig . .ll-Changeso/,illternal
--
MAV/JUNE
Perma.nent strain
stresses by tliermalloads.
scoring is to be expected
with an
increased load. An increase in rotational
speed reduces [he expected damage.
However, even high overloads do not
produce score marks if high rotational
speeds apply. An effective way to prevent
scoring is tile use of PV[).,coated worms
or the use of a lubricant with the additive
GH6.
To generate
cracks on the worm
flanks. the nominal torque must be
exceeded greatly. For this reason, cracks
are not to be expected under normal
working conditions with worm gear
drives of the tested sire. The defects are
caused by high thermal loads in combination with a local transfer of bronze.
The origin of the cracks is located within
22
=:'
Hot-strain limit
2003 • G,EAR TE'CHINOL'lJ'GY
areas of disadvantageou
lubrication
conditions and consequently higlt thermal loads. Material tests showed thermally-influenced
fringe texture and, in
orne cases, even zones where rehardening occurred ..
Internal stress analy e indicate a
change from initially compressive
to
high tensional internal stresses, caused
by high nash temperatures, These stresses lead to cracks. if the local strength of
the material is exceeded, In particular ..
cracks occur in combination with heavily pitted worm wheel . That is another
reason why pining should be avoided.
Further information can be obtained
from the final report on research project
237 of the FVA (Ref. 5).0
Vorl
Schneck-
engetrieben, Stand Juni 1996.
6. fVA·Pbrschungsvorhaben
237. Schneckenrrag{iiJligkeitsgrenun
ermitteln
lind
erilollen, Heft 518 der Forschungsvereini;
gung Antriebstechnik. 1996.
7. Kalalog der Firma Thyssen: MUTAX
Schneckenrodsatze, 1-750.
8. Kltiber Finnen chrift, Kliibersyntli GH6Ole, Produktinformation S.UScI, Ausgabe
03.93.
9. Predki, W.: Hertz'selle Driicke, Schmierspalthohen
und Wirku'lgsgrade
von
Scbneckengetrieben,
Dissertation RuhrUniversitiit Boehum. 1982.
Tell Us What You Think ...
Vi.it WWIIfI.,flrtet:."""",. .. ta
• RIll dli. Irticle
• Req .... more infonlllltiDil
• ConllCt the .1IIIon or OIJIIizItiaa ....
tionld
• Mike I ....gestioa
Or cln (147)CJ1-6IM to tllk to OIl of our
tori!
• IWlww.g,stulec/mo/og,.c,om '. www.powertuJnsm;.ss;on.co,m
H'-
--
Greater Columbus Convention Center • Columbus. Ohio • October 5~8. 2003
-
I
'Crllciib~l!e':sCPMI high ~-peed steels can giy,e you
the edge y,o'u're lookiingfor!
r--------------~.......,-- fI you WLIII beHllr,perlormanc. f""m,our brw!che .. hob., mfllin., cutt.,.. ...,
The CPU (Crucible IWIidII
uryy) Proc_
resuIIs, III a honIiogIIIoeouI~"
'WIth a IrIifDrm
cisIribuIXI<1 01atremoIy rIM carbides as s/'iiown below:
""venl or of"'" clltLlnfllooI .. 1l'J' ow CPlI'.hIgh ."..,.
mJII_, ~
CPM M4HC
A booslln
'ePiM
CobaII grade klr higler reel hart:iless and
be1!eI' woaar resiS1ance 'than M35 or M42.
IC'"
C-"1111 HI9!' SpMd
~
CPU R 11 20
CPU Rex T15
. .
High Spoood
CPM offers real advantages tor:
TIOCi'U-:
CPU Rex 76
'~_--.oe'8!'Id'~l.a1gorloal"
TooIm.Ir ..... '
~!1s' I0OIP'''''''manooI E...... ' re-sharpenillg.
IrT'fl!'CMId~~
__
~
_
.. ""'""'lIe SIiIbIo, sbsIraIIt lor aBlInIIL
wear resistal'1()8 over M2 and M3.
M4plus oobalt lor
,added reel hardness.
Cd:leII-lree but pertorrns Ike CPM Rex 45.
Hlghvanadlum
provides abrasiof1l resis'lanoe
- 'Ib!' ,edge relentionin cutting difficult matenala
Superior red hardness 'lor high culling speeds
with abrasion resistance like 115.
CPM Rex 1211 The ultimate In wear resistance and red hardness.
'HRC;70. Su.~able lor d.ry cutting. AHemalMl to carbiIle.
,ep ggdfl. II.. 11'.0
111
til_ "HS" (HI.,,. SulfUr}
modfflC6flon lor aU.r mIIcll'INI"II", II eM.l ... rI.
.".II.bl.
Crucib~le•••
TIle Too" Steel Pros·
IWWW.pOIWSE'Tlnls.mission,COffl"
45
Rex 54
Rex
.',,'a:
To find the CrllJclbl'e Service Cent'er
nearest you pl'ea.se call: 800..365-1185
or visit www ..cruc:lbieserlllce.com
,www.gsartsc.hn,ologr.c,om.
GiEAR TEICHINOUJGY
,,. MAY/JUNE
2,[103
23
__
IIPRODUCT NEWS
_
N'ew Thr,eaded Wheell Grinder
trom GI,eason
Ulltr,a Precise Hobs
RUSSEtt.
Act.uracy Class: AAA, AA,. A
Materials: Carb[de/Brl'dge/HSS
Technology: 'Drv/IHlgh Speed/Hard Hobbing
Range: 10- 500 DiametralPitch
ttOtBIROOK&
ttIENDIERSON,IIN'C.
11-11 RQ~I.lDl! North. foir !.awn. Ntw I.rsor 07~·!O
Telephone: 201-196-5445
'Fax: 201-196-5664
.STOCK.AVAI.LAB.I.E
The 400GX threaded wheel. grinder
from. Gleason meets the need for finish
grinding of gears for aero pace and
other applications up to 400 mm in
diameter and 8.0 module.
According
10 the company's
press
release, improvements
in overall cycle
time have been achieved through use
of direct drive pindles for the grinding
wheel and worktable spindles. Grinding
surface speeds of 60 meters per second
i!LMDIiBEIIDF~'iliMAGICUII'
Visit
our website
at: http://www.lru-volule_com
are also possible,
The grinder was designed to conserve
Hoar pace and for ease of use by
installing a FANUC CNC controller with
a Windows-based software interface .
.For more information,
coni act
Glea on Corp. of Rochester, NY, by
telephone at (585) 473-[1)00 or on the
Internet at www.gleason.com ..
New IGearheadlfr,om HD Systems
The CSF-XIiJ Size 5 gearhead from
HD Systems delivers 3 are-mimae positional accuracy in at package ize '!hat is
22 mm x 26 mm long.
The rated torque of the gearhead isS
lb.-in.
and
the maximum
torque
can
reach 24 lb.-in, The input of the gearhead provides a direct connection
motor, according
to the company's
to any
press
release.
Available in gear ratios from 30. 50
and 1.00: 1, the high preci ion miniature
gearhead
includes
a haft output
For more information, contact HD
Systems of Hauppauge, NY, at (63l)
231, -6630 'Or on the Internet
at
H/WII'.HDSI.lIel.
24
MAV/JUNE
2003 • IGEAIR IEC!IINIOllOGlf
•
www ..gearlecbnology.com
• www.powsnr'.f1smissi,on.c,om
_-------------1
INew G,earmo1:orsfrom Orientall
P,RODUCTINIEWS
1---------
PowerGear has a rigid design and an
optimized gear tooth contact pattern of
4,.800-m torque performance from the
smallest. size envelope, These gearboxes require no external shaft couplings or
flange . enabling the u er and OEM to
save on both installation space and
external equipment. costs.
For more infonnation. contact ZF
Great Britain of ottingham, U.K., by e-
_
mail al rob.pearsoll@if-group'.co.llkor
the Internet at. H'ww,;Jgroup.co.uk.
on
Tell Us What You Think ...
Visit www.g8'lffcllnology.comto
• Rete this column
• Request more jnformation
• Contact companies mentioned
• Make a suggestion
Or call (8471437.-M to talk to one of IU ediIon!
IMotor Corp.
The V Series quiet AC gearmotor from
Oriental Molor Corp. provides strengthened shafts tlmt mate to a series of long
life (lO,OQI!) hours) OVgearheads.
Among their noise reduction techniques area special tooth processtechnologythat
removesmachining mark
of 1-2 microns from the surtace of
motor pinions, an optimized quiet running design and new as embly techniques thai ensure trigll accuracy assembly down to the micron level.
According to the company's
release, these gearheads achieve a threefold increase in maximum penni ible
torque levels. Output power levels of 6W
15W. 25W, 40W and row are available
depending on motor frame size. Induction.
reversible and electromagnetic
brake
motors are available as options.
For more information, contact Oriental
Motor U.S.A Corp. of Torrance, CA, at
(800) 406-7484 ext, 836 or on the Internet
at
THE PURDY
CO.PO
~T.ON
ISO 9002 CERTIFIED
wwworiemalmotozcom:
N'ew G:earboxes from :ZIF
IGreat Britalin
The Grae sner range of bevel gearboxes and gear sets i designed for power
transmission and automation applications.
With a 98% efficiency rate. (he
range has graduated performance with
units thai offer superior precision, ,lIrigll
torque and. rigidity. and excellent levels
of mounting flexibility,
The Va1ueGea.r is Ute entry-level unit
and designed for OEMs. This product is
packed with ynthetic grease for lifetime
lubrication and integrates 'T' slots that provide adapti n possibilities for mounnng,
'www,power,traasmissit1Il.c:t1m
586.Hilliard StJ"eet,. P.O. Box 1898, Manchester.
cr 06045-1898
U.S:A.
Telephone: 860 649'~OOOO'• .Fax:860' 645-6293
Home Page: http://www.purd}rtransmissions.com
.f-Mail: sales@{Jurdytransmissions.com
C19!1!1THEPURIIlY
• www.gearlechoolo9y.com
• GEAR TECIINOUIGY
• MAY/JUNE 2003
25
Hermann J. Stadtfel!d
Introduction
In the past.the blades of universal face hobbing cutters had
to. be resharpened on three faces. Those three faces formed the
active part of the blade. In :face hobbing, the effective cutting
direction changes dramatically with respect to the shank of the
blade. Depending on the individual ratio. it was fOU31d
that optimal conditions for the chip removal action (side rake, side relief
and hook angle) could just be established by adjusting all major
Figure I-Pr:ocess-releva1lt .angles on a bevel gear cutting blade.
Forward Moving
Shear Crock
Chip Thickness
Equi valent 10
HSSCutting
front Face Coated
Carbide Substrate
10% Cobalt
90% Tungsten Carbide
Figure
26,
.2-C/lip
MAY/JUNE
forming mechanisms and specij'icatiotlS.
2003 • G,EAR TECHNOLOGY.
parameters independently. This. in turn. results automatically in
the need for thegrinding or resharpening of the front face and
the two relief surfaces in order to control side rake. hook angle
and the relief angles of the cutting and clearance side. Figure 1
explains the nomenclature of the process-relevant angles on a
cutting blade fora face cutter head. The effective hook angle
was also manipulated to control the bias condition of the tooth
contact, which seemed to make it impossible to avoid front face
grinding, since the front face differs from one job to the next.
The face bobbing cutter head has the following de ign specifications:
• Slot radius
• Slot offset
• Number of blade groups
• Blade spacing
• Built-in hook angle
• Cutter height
At the time, it seemed to beimpossible to replace the bias
control using hook angle changes by other geometric alterations
in blade or cutter head. Gleason Corp. found that a cutter head
offset that allows for a permanent front face along the blade
shank could be chosen. This would accommodate a wide range
of different gear set designs with small deviations from the theoretically optimal side rake angle. This relationship. together
with an additional idea. that also controlsthe bias condition, will
be explained in the following sections and is the key for the
two-sided sharpened cutting tool.
Three-sided sharpening not only introduces higher tool co t
per manufactured part, it also prevents the application of a permanent coating on any of the active blade surface . The front.
face is the most exposed to friction, pressure and the heat resulting from the drip removal action. Therefore, a coating of blade
front faces with a protective layer enhances tool life and allowable cutting speeds significantly. Coating of the side relief surfaces could also be considered, but shows far less improvement
in the performance of the cuttingproeess. In cases of carbide
blades applied for high-speedbevel gear cutting. it was imperative to use coatings on the front face for protection of the carbide grid from deterioration. The mechanical effect of the friction as well as the temperature generated by it is isolated from
the carbide by the protective layer. The coating reduces friction
and has a high temperature resistance compared to the raw carbide material, Figure 2 schematically shows the chip fanning
action.
Pigure 2 makes clear that the front face of the blade i
exposed to compressive stress, friction and temperature. The
cutting edge has its. highest exposure in the metal removal
'W'W'W.gealtechnolo9y.com-
www.poweltlansm;ss;on.com
_------------,CUnING,TOOLS
_
process during the start, of"<I cut, when it penetrates in the surface and plasticizes the steel. generating the forward moving
shear crack that forms the chip. The comer around the cutting
edge :is partially relieved from the contact 'to the workpiece
material as oon as the shearing of a chip begins. Instead of
coating. the cutting edge can be rounded, with a IO-micron
radius. This reduces wear and chipping. Teol life similar tothe
case of an all-around coating can be achieved.
The Relationship between Cutting Vefocity Direction
and Effective Side Rake Angle
In. face bobbing. each bevel or bypoid gear set requires a certain blade offset or offset angie ..The offset angle Sw determines
the differencebetween the circumferential cutter velocity and
the direction of the effective cutting velocity. The following formula shows all parameters that have an influence in the value of
.X
Relali ve Cutting
Velocity I
Relative CUlting
Velocil?' 2
Sw:
Ow .. arcsin] lw' mj2Rw I
number of blade group
wbere:zw
mil
normal module
Rw'"
radius, curter center to calculation
point 01'1 blade
Figure 3-Optimalblade posiJions !or two dif/erent-sizedjob. .
using the same cuJt:er radius and an idelltical number of blade'
groups.
The formula above hows that changes of the number of
blade groups (starts). the module (or pilch) and the cutter radius
influence the offset angle. Provided that the number of starts as
well as the cutter radius cannot change in one given cutter
design, the module or the ize of the teeth to cut will have the
only influence in Ow- To e tabu h a new cutter design. the average tooth size expected for that cutter is u ed to calculate the
value of mil' which leads to a number for OW" The relationship
between tooth si..ze and normal module is:
mIl .. circular pitchl1t
The conclusion of the formula relations above is an
increased Ow fora coax e-pitch job and a decreased Ow for a
fine-pitch job, wherethe average job that was used to design the
face hobbing cutter requires exactly the nominal va'lue of l>w
Figure 3 gives an example.
Job #1 requires an offset 1. derived from OWl' Figure 3 also
shows that the inclination between the cutter speed vector (circumferential velocity) and the relative cutting velocity (effective cutting velocity) is labeled o'w If a cutter head is de igned
according to the parameters of Job #1. then the blade lots have
to be machined in the position of the upper blade. For easier
explanation. a front face with no side rake angle was chosen; the
cutting velocity vector is therefore perpendicular to the blade
front faces in Figure I. If a cutter with the same radius and an
identical number of starts should be used to cut fine pitch lob
#2, then il. would be required to. machine the blade slots with a
much smaller offset 2 of the lower blade in Figure 3 into the cutter body. This would accommodate the smaller inclination
x
Cutler Speed
Vec'ro!"
Relative Cutting
Velocily I
z
Figur:e4-Blade witlJ Offset 2 accommodoJes offset ,angle I by
front face modification.
Dr. H'e:rmann J!. Stadtfled
started his career as head of engineering research and developmem aI
Oerlikon Geartec in Switzer/and. From
/992-2002. he worked as via president
of research and ,developmenJ'jor Tile
Gleason Works of Rochester, NY.
Statirfeld established Beve! Gear
Industries (.8GI) ill Eisenach. Gem:lall)l.
iTI2002.
IWWW.,tHJ'Wflr,t"tlsm;ui,o'o.com
.. www.g,e,artecbl1ology.com
.. GiEAR TE'CHNO'LIDGY.
MAY1J!IJNE
2.003
27
_
Grind Depth S2
Grind Depth S I
Blade
l1,2
Length
R.educ.tion by
{ Reshaping
Required Slot
Inclination
S --2
Blade Shank
Required Built-in
Slot Inclination (5
, I
Figure 5-Blade lengtll reduction after resharpening as a funetion of slot inclination.
I Cutter Axis
t
I
Slot Inclination
Figure6-Cutter
hook angle.
with slot inclination and zero effective blade
om'
between cutter speed vector and cutting velocity 2,
If a cutter head with slot offset 2 should be used to cut Job
#1, a larger offset angle would be required, which presents a
problem. This problem can be solved with a modification of the
front face angle (side rake) as shown in Figure 4. The front face
inclination in Figure 4 provides a front face orientation perpendicular to cutting velocity 1. The front face manipulation in
Figure 3 simulates an offset, different to the built-in offset of the
cutter head.
The three-face-ground blades have the freedom to change
the front face orientation in a wide range and therefore realize
correct front face orientation for a broad spectrum of pitch vari28,
-------
- CUTTIN'G TOOLS
••••••••••••
MAY/JUNE
2003 • GEAR iEC'lmOLOGV
ation. But do the jobs that cut with one specific cutter size in
fact vary from pitch significantly?
Relationship between Cutter Slot [ndinationand
Effective Hook Angle
All surfaces on a cutting blade need to have an inclination to
the shank surfaces of more than 10°. Below 10°, the amount of
material removal to clean up a worn cutting edge becomes too
high. Figure 5 has a comparison of two different cutter slot
inclinations. To result in a zero hook angle, the front face must
be ground in about the same angle relative to the blade shank as
the slot inclination of the cutter. Figure 5 demonstrates how a
higher slot inclination allows a higher angle between front face,
and blade shank and leads to a smaller amount of blade length
reduction.
Figure 6 shows a blade front face with a zero hook angle
(connection of points AI-BI-CI is co-linear with cutter axis).
The blade is held in the cutter slot that shows a significant slot
inclination. After resharpening, the blade is moved in the slot
against a stop in location A I. •. The blade shank gets shorter with
each resharpening, but the geometry above the face of the head
remains identical throughout the life of the blade stick.
The angle between front face and blade shank is reduced, if
a blade has a positive effective hook angle Like shown in Figure
7. It is possible to increase the slot inclination in the cutter head
within limits ..The highest realized slot inclination is 20° in the
Oerlikon Spirapid® cutter system (Ref. 1).
In most cases, a zero-effective hook angle is desired for an
optimal cutting action. In this case, the relationship between the
effective hook angle and the slot inclination of the cutter head
is simple. It is only dictated by the requirement of an economical and effective resharpening. The 20" angle in the case of the
Oerlikon Spirapid cutter system was a good choice for easy and
economical resharpening of the stick blades ..The measurement
of 20° also left enough room for slight modifications of the
effective cutting hook angle, e.g. to accomplish some bias modification of the flank form.
Blade System with Permanent Front Face
The Gleason Works introduced a new stick blade system in
the I970s, which did not require any resharpening or reconditioning of the front face (Ref. 2). Gleason called the cutter and
the cutting system Relief Sharpened Roughing (RSR@)and
later Relief Sharpened Completing System (RSR-C®). Figure 8
shows a three-dimensional graphic of an RSR-C blade with permanent front face. If resharpening of the blade front face is not
required, then the rules for defining the cutter geometry are
quite different. Since the effective hook angle now depends
only on the pressure angle of the blade and the slot inclination
in the cutter.the cutter slot is calculated in such a manner that
the cutting edge with the highest possible pressure angle does
not show a negative hook angle, when assembled in the cutter.
The blade in Figure 9 shows a constant cross section and was
• www ..geartech.no.logy.com.
www.powertransmission.com
••••••
_ CUTTIING TOOLS
11
••••
_
the next developmental! step that converted the friction seating
of the blades 1n the cutter in a positive form seating condition.
Those blades are called PENTAC® because of their pentagonshaped cross section (Ref. 3).
The variations of the hook angles from job to job caused by
different blade pressure angles have only a very small geornetrical!influence on the generated flank surface in the single index
face m:illing process. Those first order influences are compensated by a pressure angle correction.
To.use the permanent-front-face blade system for the continuous face hobbing method causes two additional problems (Ref.
4). The effective side rake angle (first problem) might vary from
job to job (discussed in Figures 3 and 4) caused by the different
offset angles Ow The side rake problem can be solved with the
bIade in Figure 8 by defining a cutter slot offset that is exactly
in the center ofall jobs expected for the particular cutter; This
means that a study of the different jobs cut with previous systems can tell very accurately what the average offset angle Ow
for a new cutter system should be and what the maximally
accruing side rake deviations for the extreme jobs are. It is
therefore possible 1.0 find an optimal slot position for each
designed cutter with less than 2° variation of the effective side
rake angle.
The second problem is the influence of the effective hook of
the cutting edge on the generated flank surface. This influence
is a flank twisting (bias effect). A flank twisting changes the
direction of the path of contact and therefore causes a different
orientation of the contact pattern, but also influences the motion
graph amplitude significantly. In case of the three-Sided-ground
blades. it was possible to control. the hook angle of the cutting
edge such that it is always zero (or a predetermined desired
angle). The following sections will explain the flank deviation
effect by hook angle change analytically and present an interesting mathematical solution for this problem.
GEAR
Burnishing
.
•.. from the Source:
Remove nicks, burrs, heat treat scale
800 Improve gesr tooth surf8CB.
09IIr 30 J&lI'I ago. er 1taIr1IInI: danloped the gear
bumlaIllJIg
1'fOC"S'. Pot your tna! In the .pt!Oplo who InYontO<!the PrQ0800.
MACIw. FEAJI8a
IHCWDl:
• ~ullVautomated Il.'{$tems.
• H~h speed machines
.. Potentec Oeroc
OscHlafion System.
• Automatic sphsrlcol
p<>sIllonlng.
• TrI~va,labledie design
.. HOlilontol Of vernecr axis
rnocrmas.
ot gea. type s.
- VO~.. ty
For additional inionnation 011 li.I!IIc
Burnfshlog rmd/or funct!onal.im(
Lnspectlpn: visit our WItlls1rlt at:
WWW:frwgears.com
Heartland
1205 36th A~
Ww!
Alodndfbl. MN S630B U S III
Ph l320l162-8182
...
(J2017!l2.!12!10
E·ri'ItI1.lfWONlfIoOi"*"-aIp.'IXI'I'I
Analysis of the Geometric Effects to the Flank Form by
Contrelllng tbeFmnt Face Orientation
The publications of Kotthaus (Refs. 1 and 5) teach that to
maintain a sufficient side rake angle,especially to control the
flank.surface twist, the front face has to be variable in two angular directions, the side rake angle and the hook angle. The effective hook angle is the inclination around the normal cutter
radius (Figure 10) between the cutting edge and the cutter head
axis (Figure 7). The blade in Figure 7 is oriented such that the
relative cutting velocity vector lies :in the presentation plane.
The effective hook angle is a function of the front face orientalion with respect to the blade shank •.as well as the angle of the
blade slot in the cutter head (built-in hook angle) and the pressure angle of the cutting edge.
A change of the blade pressure angle has a direct influence
onto the pressure angle of the manufactured tooth flank. A
change of the hook angle in a face hobbing cutter blade causwww.p,owe'I',rfa.n'smission.c,om.
GROUND GEARS- ren or ren lhousan,d
i
For small to medium quantities of spurs or helicals that have to
meet close-tolerance AGMA or DIN specs, our Relshauer grinders
and M&M gear analysis systems are the perfect combination.
For Long runs, we offer the unique Liebherr CBN grinding
process with full SPC quality control and documentation.
So whether your needs are for ten or tens of thousands, we
invite you to join the growing list of INSCO customers who rely on
us for consistent quality, reasonable costs, and reliable delivery.
PHI)NE:978~448~6368
FAX:978-448~51'55
_
rnsco
www.getUlechnology.com
WEB:lnscecnrp.cnn
412 Main St~..eet: Groton. Massachusetts 01450
RPOIlATION
ISII 90011 IRegistered
• GEAR tECHNOLOGY
• MAY/JUNE
2003
29
_------------CUTTIINGiTOOlS------------crowning
!cutter Axis
as a rather complex. flank form modification,
The blade systems that allow a change of the hook angle use
'this freedom for flank form and contact movement
~
I
ty) optimizations.
Studying
tor of those systems found
same
optimizations
the literature
it
physically
byavoiditng
(adjustabili-
shows that the invenimpossible
to allow the
the individually
controlled
during the past 30 years to' develop a
front. face cutter system with the same freedoms of
front face. All attempts
permanent
the one with front-face-ground
blades failed.
New SPIROFORMTM Cutter and Blade System
A~ interesting
technical
challenge
was the attempt to devel-
op a cutter and blade system that allows al1 the freedoms
three-face-sharpened
sharpened
Figure'" Cutter with slot inclination and positiveeffectiJ!e
blade hook angle,
on the two
ide relief surfaces only.
a discovery
Finally,
generated
of the
blade, yet using a blade that is shaped and
by different
was made that relates the epicycloids,
hook and side rake angles .. The idea is to
find the radial location of one point along the cutting edge of a
given blade that lies on the same epicycloid,
generated
by a
blade with different hook and side rake angle, It is assumed
the given blade consists
of a permanent
that
front face, no hook
angle and a side rake that is constant along the shank. The hook
angle of this system is created by an inclination
of the slot in the
cutter head.
Figure 11 shows the two different blade types with the roll
circle-base
circle kinematic
"attached"
to the front-face-sharp-
ened blade.
B [ of the two blade types are identical
to solve is to find the locations of the
Points At and Ct. along the existing front 'face of the simplified
blade. The geographic height of the blade, with respect to the
The Points Band
Blade
Shank
(Figure 10). The problem
cutter head front face. remains constant.
To
find the location
of Point A ['the
epicyclical
kinematics
with roll circle and base circle are rotated clockwise.until
A con-
tacts the front face of the new blade ..This is the location of A l'
Figure 8-RSR'-C stick blade witl:permauent front face and TeetangUJIUCTOSS
The
movement
from A
to A[
circle center, superimposed
section.
requires
'by
the base circle. The relationships
es a flank twist and a change
in profile crowning
and pressure
a rosatioa
rotation
around
the roll
around
the center of
for the solution
of this prob-
lem are shown in Figure 6 and expressed
by the following
for-
mulas:
angle.
Figure 10 shows a blade with the Points A, Band
cutting
a
edge that has a positive
C along a
hook angle. The figure also
(1)
shows acuning edge without any hook angle (Points AI' B, and
path generated by A is different than the
by A [' The curve associated with A I has a simitar, but not identical, shape to the one generated by A. Thetwo
curves are inclined and shined. relative to each other in z-direction, That means the spiral angle of curve A decreases relative
to A r The opposite happens for curve B relative to B I.
C,). The epicyclical
or:
one generated
So sin (-4lo-j
Thecoaclusion
of 'Ihe last paragraph
is that the hook angle
where:
Rb(jx' ..
301
mentioned
change
in profile,
represents
x-Componeni
of Cutter Radius Vector
(Blade without Hook)
Rblx".
causes a positive flank twist. between heel and toe. This, together with the already
+ 3..,) + Roo ° sin (0..,) ",S' sin (-¢lo- j + 3",+ !Pit) +
RBo sin (0", + CPHwk + CPt')
(2)
x-Component
of Cutter Radius Vector
(Blade with Hook, rotated into zero Hook Plane)
EXOx ...
MAY/JUNE 2003 • IGEAR IECHN:IJ,lIJGY • www.geartechrro.logy.com
x-Component
of Vector from Machine
" www.powerlra.nsmiSSio.n'.com
Center to
I-~~~~-~-~--
--- ------------------~~~~~~~~~---------------------------
.--
---
CUTTIIN'GTOOLS,
_
Cutter Center (Blade without Hook)
x-Componem of Vector from Machine Center to
Cutter Center (Blade with Hook, rotated into
zero Book Plane)
Radial Distance (Scalar of EXfu)
Cutter Phase Angle
Swivel Angle
Offset. Angle (Face Bobbing)
Scalar Cutter Radius (without Hook)
Rotation of Cutter Center around Base Circle
Scalar Cutter Radiu (willi Hook)
EX3x'"
s...
'clio'"
j ...
'0",...
Roo'"
'IP" ...
RB• ..
Angle between R.8 and RBO
Rotation of Blade with Hook Angle around
Roll Circle (Cutter Center)
<PHook""
<!le'"
Between 'P'", and 'Pc is the following relation hlp:
(3)
where:
l.gMuut;ng g~ar' , •
lOlllltr
••.
Number of Teeth 'Generating 'Gear
Number of Starts Cutter
Figure .9-Pentac
Wanted i 'P". out of formula (2). The mathematical
olution
is conducted w,ith an iteration algorithm. The difference
'between AI and A2 i.s!l. !l.is calculated as shown:
(4)
stick blade with perma.nentfront
face ,and
pentago".shaped cress section,
I
!lis the displacement of the normal radiu (along z-axis) of
'e,IB=~.IB.' -, Il,.. --. .... AA
Normal Radius
point Az to come to point A I that cuts the arneepicycloid
as
Il
I,.B"
-,
.
C
point A. The epicycloid cut by AI wiU differ [Q some extent
from the de ired one, cut by A. The hown approach i the
physically closes I. possible approximation, that infinitesimally
observed still repre ents a mathematically precise solution. In
z
practice, it causes difference over the entire Hank surface of
only a few microns and therefore can be neglected.
I The analog scheme is applied to find point CI (Figure.7),o. I f'ig.ure J,(J-RelatUmsllip ,between' hook ,angle and Icycloidal path
rotation of the epicyc!ical kinematic in counterclockwise direc- I (If diffeumt .blade poi"ts.
tion brings C (Figure 7) to the front face of (he new blade.
The possibility to influence the blade spacing in the cutter
According to the above shown solution. any desired number
head by grinding the front face of either inside or outside blade
of points along the cutting edge with one particular book angle
further back results in a tooth thiekne s or slot width change.
The SP[ROFORM blades call. account for that feature, too. A
can be converted into a point on a cutting edge without hook
tooth thickness adjustment is done by splitting the required
angle 0, a:ny other chosen hook angle.
Depending on the mathematical function of the new cutting
arneunt and, for example, inereasing the radius of the outer
ledge (circle, ellip e or higher order). three, five or more points
blade cutting edge and decr-easing the cutting edge radiu of the
can be tran formed from the original tothe new cutting edge.
inner blade by half the amount each.
Three points, one on the tip, one in the center and one on the
Summary
end of the cutting edge, deliver a sufficient definition of the cutA method was found to, convert a. side relief and front-faceting edge function to capture lite characteristics of the different
sharpened blade, held in a face hob cutter head into a blade that
front face hook angles.
has a permanent front face and is profile shaped or re-sharpened
www ..pow,e.fuansm.iss.ion'
..com.
www.gesrtechn%gy;,com
• ,GEA!RnCHN'()LOG,V
• MAV/JUNE
2003
311
_-------------CUTTIIN,GTODlS-------------
Figtl"'/! ll-Epicyclical
kinematics
'(J/
two diffenllt blade types.
on Lite side relief surfaces.
The advantage of replacing the old style three-face-sharpened
blade i in particular the permanent character of the front face and
its coating. The new carbide high-speed cutting depends to a large
extent on the correct fronl face coating. AU gear sets, designed with
a system using three-face- harpened-blades can hardly be manufactured using high peed carbide cutting by replacing the high
speed steel blades with carbide blades of the same geometry. To
send a set of blades to a coating facility after resharpening requires
more expensive carbide blades in torage and includes the cost of
up 10 J 00 recoadngs of each blade. Thi. procedure increases the
tooling co I by a factor of eight.
The new SPlROFORM blades allow conversion of all older
"three-face-ground" jobs. into a two-face-sharpened blade system
with a permanent front face coating. Gear sets do not have to berequalified after d1e conversion inee the flank surface geometry
tays identical to the original.
Figure 12show a photo of a SPIROFORM cutter with 1.60nun
radius and 13 starts. The SP[ROFORM system 111 es no bottom
blades. This provides, a very solid and stiff cutler coastruction The
blades used (TRJ-A ® or PENTA:C) provide sufficient roughing
action onthe secondary cutting edges (clearance sides).
rent face coated blade provide good surface finish and
improved productivity. The SPlROFORM blades are stepped in
their building height. uch that the tracks from outside blade
and in ide blade blend mootWy together in the root fillet,
Figure J 3 shows an example of a conventionally
cut ring
gear. The gear to the right is cui. using a SPIROFORM cutter
and a Phoenix" free-form machine. Surface finish and root
blend are superior for the new cutting sy tern. Cutter heads and
blades of the newly developed system are not limited to a certain machine tool brand, but can be applied on CNC bevel gear
generators of The Gleason Works, Oerlikon Geartee A:G and
Modul-SU with no limitations. 0
R·derences
Figure 12-Tlle Sp.ir%rm cutter head witt: a 160 mm radius
and
13 starts.
I. Konhau . E. MWutsch!dllichcs Herstellen von Spiralkegelrddern
in kleinen
lind gro/3en Seriell", MaschinenmQrJa. 83. Jg. Hefl 13. Sepl. 1977. Wiinb!U8.
Germany.
2. Ryan, A. and C. Thomas. Cunerhead Assembly for Gear Cutting Machines.
U.S. Patent #4.060,881. December 1977.
3. Stadtfeld, H. PENTAC: .Ii New Cutter Sy.fll'm for Face Hobbing and Face
Millin.g. Gleason publication, Rochester. NY. April 1998.
4,Krenzer, T. Cutter and Method for Gear Manufacture, U.S. Patent 14,525.1 Og,
June 198:5,
5. Kouhaus, :E.. End Cutter Head, U.S. Patent 13,760.476. January
ore: RSRGII TRY-Ace.
PENTAC'I.
SPIIROFORMTW
nee trademarks
Gleason Works.
Spirapid~ is a trademark of Oerlikon Geartec AG.
Tell Us What You Think ...
Visit www.• IIltfIChnology.cDlflto
• RIle this article
• Request more infonnation
die author or organizltions mentioned
• Mike I suggestion
Or c81118471437-1i604 to tllk 10 ona of OUt editors!
• Contact
Figure 13-LeJt side-conventiorlal, right slde~cut willi
Spir%rm cutter head.
32
MAY/JUNE
2003 • IGEAIRIECiIlN:·lIl0GV
• www.gea,.teclmology ..com • www.p,ower,ransmissio.n.com
1%3.
of The
ADVERTISER INDEX
USE IRA'PID IREADER RESPONSE to contact any advertiser iin this issue
www.geanechnology.com/rrr.htm
RSlpid Reader IResponse: It's FAST! It's EASY! It's ONLY ONLINE!
Advertiser'
Page
[-!!I.lil
P~on8
AGMA
lolarnal
(925] 285-3926,
Lmupli@agileitp8I1nel'$.~Qm
ww.ueCUJllirajs.com
(703) 614-11211
[email protected]
WWW.gluexpa.£Dm
(8QO] 342-1571
www.aia1l1occo.coml
(216) 431-4492
[email protected]
\NWW.l!!mericanlMll.llrtlling.com
(1i3Ol'!169-16401
bevel,@arrowg,ear.com
'www.IITOWQall;co:m
(241) 314-&155,
IIlls@asbgelr:cam
www.l.haur.com
A~J M!!:thin'!y Co.
(704) S2I-09Q2
e.simlcbi:[email protected]
NW Systems Co.
(241) 544-3152
Arrow Gear Co.
Ash Gear
a Supply
B '" IR Maebine 8I1dl'Gear &01]1.
(800)2JI-Il6511
inquirygt@brgea(.com
www.brgtucom
Baril, Intemationa'i COI]I.
(147]m-"28
pilople@bniL,com
www.hrilcOlll
Boum 5 Koch Machin.e, Tool '1:0.
(,15)'96HO'3
bogr:[email protected]"n.".t
TIIelBrolch MlrIiIrs l'ncJUill.lrsal Gt., CII.
8
Dr.IKliser (S.L Munlon]
Dragon Precision Tools Co. 1lId.(Grll
sal,s@brnchmaslel'S.com
'WWW.broachmal!all_com
(8001 365-U85,
c!i!!cil!le@c!i!!cibfeservice.com
www.crucibleservicl.·com
(800) 175-13911
[email protected]
(440)331-1)038
gallenco@msn,com
18001 563-3442. (530) 885--1939'
A1lm Co.I
www.dragon.co.kr
·www.ga·llenco·.com
(8001221-6455.
(815) 338-7800
(4141769~OOn
www.dunl-bar.com
sales@d!f!a-bar.com
usa@Iaessler-ag,'ch
(586] 323'!m1
Fonnu Precision Gear IRC.
(3151488,0100
tOhwri@ntlCQngear.·com
(2116)762,3333
[email protected]
Gleason CoI]I.
(5I5).t73-tOOO
dmellon@gl'eason.com
G1'150n Cuttingl Tools Corp.
11151811-8900
dllNlton@gl'eason.comi
Th' Gteasonl Works
1585H73- 1000
dm&ltllD@gl'elsQ~.com
I'ndllll TecbnologiH, IIIe.
(440] II95-462l
lI'ndiana, Tool/lndiana Gllr
(574Il136-,Z112
InKO Corp_
19781441-63&1
l'nttlSUlt' TQoll'CQ'1!.
121616711-1011
The Gear Works-Seanle
Inc.
www.'gleason.,eom
www ..gallenca.com
IIIH@;nSCDCOI]I.CO!!!
www.inl.lllltltooICDJ.com
IlWg •• [email protected]
I1W Hurtllllld
ICarDSharpenlng
www ..gearmotiolll.com
www.itwge.rs.com
www:k.oroind.'com
:S" rviCl
www.lecountcom
LeCollll1inc.
[email protected]
Ullb a'rr Gear Teclmology Co.
(ml429-122S
iinlo@lgtlillb'her~Co!!!
mG ,milliGem Nonl!-AlMrlcl
1151)621-4554
www.minige.l'S.c",
www.mwgear.com
{3llO1425-4419
Midwesl Gear IIITool Inc.
Nacbi Machining Tecbnol'olY Co.
11.""
Niagara Gllar CoI]I.
45,47
[5161154-11923
[email protected]
'[5861 263-0100
[email protected]!!!l
[email protected]
_"'MIID,rege.,.com
IIBC
111601138-2525
[email protected]
www.plnygllf.com.
Process Gtlf/BIDDlllndusttill
41
,(841)67'1-1631
[email protected]
The Purdy CoI]I.
25
'18601649-l1000
[email protected]
Ruuall. Holbrook 81 Handerson Inc.
2f
12011196-5445
[email protected]
www.lru-valulu:om
45.0BC
'18471649-1450
slles@sI6l·su.com
www .• lar-Iu.com
P'eny TnlmoloD¥ CoI]I,
Slar-SUI ilnc.
(800) 441-2l92. (7161In-3131
www -,f1owsr,transmission.com.
www.geartflchnolo!J'y.com.
GEAR TH:HNOUIGY
'. MAY/JUNE
2003
n
_------------.,CUTTl:NIGT'OIOLS------------Perfnrmanee of Skiiv!ing Hobs in Fiinishlin'g
lnductien Hardened and Calrburize'ldGears
Ta'keji Sugiimoto, Akira Ishibashi, and Masataka Yonekura
In
order to increase the load carrying
made from. carbon and alloy steels, The
able to use hardened
gears. The quench-
capacity of hardened gears, the distortion
gears to be skived were hardened by two
ing in the hardening
process of the gears
of gear teeth caused by quenching
different methods: inductionhardening
brings about heal treatment distortions,
resulting ill a reduction in the accuracy of
must be
and
(skiving)
carburizing. The induction hardened gears
the case of large gears
the gears. To effectively
hobs with and without coated TiN [ayers
with a hardness of about 600 Hv can be finished easily by a carbide skiving hob without coating. However, the carburized gears
with a hardness of about 750 Hv were very
difficult to finish due to the severe flank
wear and/or chipping at the cutting edges
were used for finishing
when a carbide hob without coating was
when the hardened
u ed. However, when a carbide skiving hob
grinding,
removed
by precision
In
and/or grinding.
cutting
with Large modules, skiving by a carbide
hob is more
economical
than grinding
when the highest accuracy is not required.
In
the present
investigation,
hardened
carbide
gears
with coated. TIN layer
and the flank
011
was used,
the tool
10.
only,
used for finishing
chipping
the
Pressure angle
occurred
Carbide
011 the
(carbide
side) of the cutting
other
side
(leading
for accurately
(mm)
No. of gashes
ing technique
tools
by coating them with a
for the solid-type
gear cut-
ting tools made from high speed steel and
, carbide
has
progressed
remarkably.
Coated carbide hobs of the solid type and
In order to. increase the load carrying
capacity of gear transmissions, it is desir-
with a conventional.
geometry
were
effectively used for finishing low hard-
-
nd skiving hobs used in the 'Bx,periments.
liS
20·
20·
I
120
9
150
10
1.20
10
I 8
20·
120
10
I
i
,
(0)
Hob (E)
Hob (F)
Hob (6)
8
20"
8
,20·
8
20·
150
150
1501
'I
I
ness gears with a small module (Ref. 8).
However,
:it was very difficult
the . olid-type
carbide
to make
hob economically
when the modules of the work gears were
large.
Brazed-type
carbide skiving hobs with-
,12
12
il2
30•
30·
P30~1
TiN
,130·
hardened
P30
II TiN
However, a coated carbide hob with a su1-
out coating have been used for finishing
Inclination
0°
O·
30·
30·
Hob material
SKH55
TiN
P20
KI'O
MJiO
,llP20
none
none
none'
I none
of
MAY/JUNE
gears
Introduction
cutting edge
34
hardened
thin, hard material. (Refs. 5-7). The coat-
which give the same tool
I
Coating
geometry
(Ref. 4), Tile lives of gear cutting
side).
the coated skiving hobs with
,I
1
finishing
to produce
8
Outside
diameter
hobs with special
skiving hobs) are very effective
can be increased
I
20·
of time is
highest accuracy is not required.
by the flank wear
which
ill order to increase the lives
of skiving hobs, it is strongly suggested
IIIHob {c1 Ii Hob
I B
Module
of conventional
a
is economical to. finish the hardened gears
hardened
edges with a tool angle smaller than that
II Hob [BI
Hob (AI
finished by
the gears are Large, a longperiod
angle on both sides of the cutting edges.
--T
are
by cutting using a carbide hob when the
of
Tablel-Specifications
gears
One of the authors designed
bide hobs
helical gashes,
Kind of Mobs
and/or grind-
super precision gears with a mirror-like
tooth surface using a CBN grinding wheel
(Refs. 1-3). However, when the size of
life
Even
Therefore,
teeth.
such as skiving
required to finish the gears by grinding. It
fixed side (trailing
F.igure2-TransI!erse section o/hardened
operations
after
finishing
a factor of about 7.
It was found that the tool lives of car-
and/or
lIobs used for culting
accuracy
by using additional
gear grinding machine capable of making
the tool life increased by
gears were governed
Figure I-Carbide
tests,
their
hardening,
The highest accuracy can be obtained
with the skiving hob with the coated layer
on the flank
improve
gears,
ing, honing, etc.
both the rake face
by a factor o.f about
increased
we must
utilizethe
2003 • ,ClEAR lEiCiHNII'LOGY
•
1
,
www,geartechnology,com
gears
with
large
modules.
ficiently high accuracy for filnishing hard-
• www.powe"Uan.smis.sioll.com
_------------,CUTTINGTOOLS::.
enedgears
with large modules
was not
found :in the market recently. The progress
in both coating
and brazing
techniques
for induction
carbon
hardening
alloy
SCM420)
gears while low
steels
were
•
(SCM415
used
carburizing
for
makes it possible to produce high accuracy
gears. For cutting tests, spur gears with a
brazed carbide bobs with coating.
module
Recently,
the authors
have been able
to obtain a coated skiving
hob and con-
dueted the cutting tests wi.th some interesting
results.
The
new,
unpublished
of 8, a pitch circle diameter
208 nun and a face width of 60 mm were
Using the gear blanks with a hardness
of about
200 Hv (normalized
steen,
gears were produced
by Hob
carbide
rough-cut
skiving
in this
A. The gears were hardened
will be presented
paper.
hardening
Cutting Tools and Test Gears
Specifications qf Cutting Tools. Table
I shows specifications
of gear cutting tools
(hobs) used for the present investigation.
of
For induction
was
hardening.
moved in the direction
space
for the alloy steel. Quenching
some additives
type and made from high speed steel. Hob
quenching
B is of the carbide, brazed type wilh no
After hardening,
ar a temperature
ing hardened
brazed
for finish-
gears and are called "skiv-
ing hobs." No cutting action occurs at the
hours
a Vickers hardness
temperature
at a
of about 1,200oK in a mixed
of propane gas and
for five-and-a-
half hours, the temperature was decreased
non-soluble
0
were tempered for two hours at a tempera-
of conventional.
ture of about 4700K to obtain a hardness of
be finished. The carbide blades of Hob F
were
Figure 2 shows the transverse
with
a TiN layer with a
of hardened
of
about
5J.1rn
Figure 3 shows the hardness
while those of
gear
teeth
section
distribution
below the surface of the hardened
teeth
blades of Hob G were coated on the flank
made from three different materials.
The
only ..Figure
hardness was
car-
bide hob (Hob B), a skiving hob without
coating
(Hob E) and a skiving hob with
coating (Hob G).
Specifications
of materials
gears
and specifications
are shown
in Table
of test
2. A 0.45%
plain carbon steel (S45C) and a medium
carbon
measured
at an
indenter load
alloy steel (SCM440)
were used
>"'
:5
500
.." 400
.§
a
300
.c
...~ 200
[)
;;:
100
0
4.55 5.5
1.5 2 2.533.54
Depth below surface (mm)
(b) For SCM440 steel gear
0 0.51
Figure .3b-.Hardness of hardened teetll.
800
>
700
e 600
'"'"
" 500
.§
j
.~ 400
of 9.8 N. The maximum hardness of induc-
...Ii:
tion hardened
:>'"'
gears is about 600 Hv and
the thickness of the hardened layer is about
of Test Gears. Kinds
Hardness of hardened teeth.
700
of lest gears.
Hobs C, D and E were [lot coated. The
[ shows a conventional
Figure 3a
about 750 Hv.
coated
thickness
I
oil. After hardening, the gears
skiving hobs was made smaller than that
action at the tooth bottom of the gears to
0.5 1 1,5 2 2.5 3 3.5 " 4.5 5 5.5
Depth below surface (mm)
(a) For S4SC steel gear
III
ventional
cutting
6+-~~-+~~~+-~~
a
of
from 1,200"K to I, [20 K and quenched in
hobs to prevent
100
of
rake angle of -30 in the case of the conhob. The whole tooth depth of
u
600
was conducted
alcohol. After earburizing
to a
;;:
about 600 Hv (Fig. 3).
gas, which consisted
0
1
~ 200
of the heat-
the gears were tempered
of about 4700K for two
The carourizing
600 r 600. 750, 750
--
cracks on the tooth surfaces.
nation angle of the side cutting
these hobs is 30°,. which corresponds
of
J;l
to prevent occurrence
to obtain
I
500
using water with
outside edge ofthe hob blades. The incliedges of
S45C, SCM440,
SCM415, SCM420
::l 400
1:!
300
1,150oK
of about
ed. teeth was conducted
(Fig. ] 9a). Hob A is of the protuberance
geometry
>"
:5
The tooth
surfaces were heated to a temperature
therefore,
Hobs C-D are of the carbide,
Material
600
speed of about 300 rom/min. to heat over
and to a temperature
type with a special
b" 60 mm
700
and
of tooth trace at a
angle of the side cutting edges is 0<>and,
protuberance.
Face width
a partial coil
in the tooth
inserted
about 1.,250oK for the plain carbon steel
the tooth surface of the gears
o·
.1
tingedges.
infinishing
Helix angle
or carburizing.
the two facing tooth surfaces.
no oblique cutting is conducted
Z. = 26
Hardnsss! Hv)
by induction
Hobs A and B are of the conventional type
with a rake angle of 0" for the outside cutThis means that the inclination
No. of teeth
u ed.
results obtained using non-coated
bobs
Table, 2-Specificltions;
of test gellrs and
k;inds of ear materials.
and
3 mm. The maximum hardness of carou-
"
300
200
100
0
0.2 0.4 0.75 1.5 2.5 3.5 4.5
rized gears is about 750 Hv and the thickness of the hardenedlayer
is about I. mm ..
Depth below surface (mm)
(c) For SCM415 steel gens
The accuracies of test gears (rough cut
gears) deteriorated
www.powelu,snsm;.ssioll.com.
appreciably
by harden-
www.g.e.lIflechllology.com
F.igure 3c-Rardness
• GEAR lE'CHNO,LOGV.
of hande'led teeth.
MAY/JUNE
2003
35,
_-------------CUTTING
I
Top
-
Bottom
I'>¥-rl 7)
'"> r?"1rI,
~
~
77"'1''''
I Before hardening
I
77 Y'TY'rH
,.,
J
Hob F was used for hard finishing (Table
c::
pitch errors of the test gears before and
~
r-"77?7'7"T77'7rn"",
After skiving
After skiving
!20~~
~amm
I), Figures 6 and 7 show the cumulative
80
00
after skiving.
40
From Figures 4 to 7, it is understood
20
t
!2D~~
~~mm
(a) Tooth trace
to
5
0
-5
-10
Number given 10 hob blade.
(b) Tooth profile
Figure 4-Tooth
trace and profile errors
of induction hardened gears.
that the decrease
Bolcom
Tip
hard
Figure 8-Wear
width of all working
blades of Hob E without coating used for
a3-
'''77'''>,17)17r
rrnn;;7J/?77?'
After skiving
¥77)J;;;ff;'7,~
£l
/>')7)'»>?h77?77n-
~
!20~~..
(a) Tooth trace
-40
10
15
0
-5
-10
-15~
25
lO
0
after finishing
Tests and Tool Wear
2003 • GEAR lEICHNIlU)GY
of two carburized
blades
E
Hob
gears.
of the hob
were
ed to finish the gears. The dark: mark.
len
side (leading
the empty mark shows the wear width at
capacity
diameters
capable
machine
of finishing
with a
gears wi.lh
up to 1,000 mm was used. The
shows
the flank: wear width at the
the right
side) cuttingedges
side
(tramng
side)
while
cutting
edges.
in Japan. Using Hob A made from high
When coated Hob F was used, ItO carburized gears could be finished before
speed steel, rough hobbing
of nonhard-
the flank. wear reached about 0 ..1 rnm,
under the fol-
Figure 9 shows the flank wear width of
a cutting speed of
28
a hob feed of 2 rom/rev. and a
used for
The conditions
kiv-
gears were a cutting
a hob feed of
all working
blades of Hob F after finish-
ing 10 carburized
gears. Figure
10 shows
the effect of the coating on the tool lives
of carbide
skiving
hobs, indicating
the tool lives increased
seven
when
the coated
instead of tile noncoated
by a factor
hob was used
hob.
of
desirable
to lise a coated hob such as Hob
F with the coated layer on both the rake
the tootli profiles and tooth traces of test
face and the flank of the cutting
gears before hardening
However,
(after rough cut-
• 'Ww'W.geartechnoJogy.com
that
of
In order to increase the tool Iives, it is
Changes in Accuracy of J:est Geers.
Figures 4 and 5 show the accuracies
MAY/JUNE
blades
of carbide
of test gears, a hobbing
cutting fluid was applied.
Fig.ure 7 Pitch errors of carburized
gea.rs before and after skiving.
edges)
8 shows the
Hobbing Machine
and Cutting
ConditUms. For rough and finish cutting
speed of 75 or 52m1min.,
Number of teeth
0.05 mm after finishing
gear. Figure
Twenty-three
IJ
gears,
of the hob
very important to economically improve
the accuracy of the hardened gears.
2 romJrev. and a depth of cut 0.3 mm. No
-60
width
(side cutting
iog of the hardened
-50
wear
ishing by carbide skiving hobs becomes
direction.
-10
hob (Hob E) was
the carburized
flank wear width on all working
final depth of cut 0.3 mm in the radial
-20
-30
;;: --40
3·6
used for finishing
ing (Figures 4 and 5). Therefore, hard fin-
mlmin.,
30
20
g
..c::
"
8
t
only a single
lowing conditions:
40
experiments.
blades exceeded
ened gears was conducted
!2
to 52
rized gears.
machine was made by Kashifuji Co. Ltd ..
Figure 6-Pitch
errors of induction hardened gears before and after skiving.
~
speed
75 mlmin.
9- Wear width o/all
working
blades 0/ Hob F usedfor jinishi1lg carbuFigure
I
-80
to
15
20
Number of teeth
5
the maximum
-60
5
the cutting
from
When a noncoated
0
Cutting
0
reduced
mlmin. in the following
Number given to hob blades
0
"
~
was
(b) Tooth profile
20
;;:
a single piece of the
test gear. Therefore.
20
!20~~
40
.t:!
flank wear width became greater than 0.2
40
't...,5mm
0/carb.uri<.6d gears.
-20
speed of
"C
Figure 5-.Tooth trace .and pr"Ojileerrors
~
~
g
gears.
gear at a cutting
mm after finishing
After skiving
~10mm
by
induction
75 m/min, and a feed of 2 mm/rev .• the
IAadiJlg 5ide f1.1..ok
Tf'IIjJjh8. hide nuJlk
60
'"'"'"e""
hardening
-
80
~
After hardening
the
and the carburized
the carburized
100
5:t
~After
was improved
for both
the coated Hob F was used for finishing
Before hardening
Before hardening
caused
Effect o/Coating on .TooI.Life. When
120
~.
,..,..",.,-"
;''''}/7)'
finishing
hardened
Root
~
'";7>;-'''''7~
in the accuracy
by the heat treatment
-.15
finifJhing carburized gears.
Top
skiving)
(after skiving).
!100
...
-5
7'Y-r,;;,n;/J).
(before
For rough cutting, Hob A was used, while
.....0
1'>1>'7)"7'
hardening
E 120
a
After hardening
after
and after hard finishing
0
~
~
"",,}
ting),
140
Before hardening
After hardening
_
isn
Root
Tip
TOOLS 11
the coated
• 'Ww'W.po'Wertransmission.com
edges.
layer on the rake
_-------------I'CUTTI'NIG
face
wom
i removed
cUlting
completely
edges
when
the
160
are sharpened
by
140
TD,DLS
-K::tb E
"··"Hob P
HobG
regrinding,
Recoatiog
of the reground
~120
hob may
accu-
9100
racy. Therefore. addit.ional cutting tests
were condu ted. using a ski \ling hob with
I~ &0
bring about a reduction
in the hob'
only,
flank wear
"
c:
~oo
the coated layer on the flank
Figure II show
the
:i40
width
20
of all. working blades of Hob G afler cutting seven carburized
gear .
By
o·~·~~~~~~--~~~~~
o
5
compar-
ing Figures 9' and II. it can be seen that
with
the coated
,
hardened
10).
00
"
0::::
IOf about 600 Hv, the 1001 life
increa ed appreciably
in campari an
with that of the noncoated hob. Hob G
flni h 16 gears before
so
...,"
gears with a hard-
meso
could
100
IE
~
Hob G was used for fini bing
the induction
40
"
.c
il,
~
>liI<1IanIi.
-1..adlJl1 Ide On
-TnilIq
20
the wear
0
IS
width reached 0.05 mm. Figure 12 shows
the flank
wear
width
joo~
t 40
J 20
resemative
t
TiN layer. Figure]4
how
·15
afall
warking
-
..
- 'TrIiMI :.. _.
- ...........
patterns on'j1ank of .hob'
16 illductioll .hardened
f'igul',e IS-Wear
G -after cutting
gears.
.
0 J-...-'--~~"""';''''-~_~.....I..--I
15
10
5
0
-S
Number given 10 hob blade.
-10
Cutting. edge
bya
Figure 12-Wear widti. of Hob' G after
j1niching 16 pieces of induction Itlfrdened
gears.
wear patterns
G after cutling
flank.
even
onJy. It was estimated
that 'the flank wear on the right
ide cut-
ling ed e wa
increa ed appreciably
th occurrence
of chipping
at the trailing
appreciably
by
at the caning
flank:
The rea on wbythe
cutting
wear
edge
YU:i..
e
~
is
edge i discus
section.
igure ~5 how
ed in the next
wear pattern
flank of Hob G after cutting
gears.
0
chipping
on the
16 induction
occurred
at
f'iguJlt 1J- Wearpattem ··,m rake jace
andJbmlc of coated Rob .F after ~ulting .10
ca~liurizedgears.
and right
tiveJy
induction
abom
of the coaled layer on the flank. The difterence lin the wear widths on left ide
' I
.
hardened
ircumIc-renlial section
-
the hardnes
gears
0.)
i comparaof the
is lower
by
150 .Hv than that of carburized
gears. resulting
ting edge,
www.powef't,ansmissio.n'.c,om'
-
ide cutting edge
mall because
verymoJl.
the effectivenes.
£'~-l
P1
th cutting edge • and the wear width was
indicating
I
.
greater than that at the lead-
ing cUlling
hardened
-1.0
gears, This hob bad the coated
layer on th
width
..
gear . Both the rake fa e
and flank of this hob were coated
edge.
..
blade of Hob F after cutting
IOf Hob
-5
pieces ,of cariJl4rized gears.
on the rake face and the flank af the rep-
carburized
0
Figure U-Wearwidlil's
Weal' Pattem on Flank. Figure [3
shews wear pattems that were produced
on the flank
5
blades of Hob G after /inis/,ing seven
16 indue-
tion hardened gears.
W carburized
10
Number given 10 hob blades
on all working
blades of Hob G afl.er finishing
F,igure J4- Wear patterns on:flallk oJ.Hob
G ofler cutting ellen carlJur{zed geal".-.
120
layer on both the rake
face and the flank (Figure
When
by about
shorter
q!coatiJ.lg rJIIt(Jollife.
Figure lO-Elfect
with that of the hob
30% when compared
10
umber of 8= flnished
the coaling on the flank only is effective,
The tool life becomes
_
in no chipping
at the' cut-
IWww.gflsrtechn'ology,com
bl Normal '!eCtion
FiguJ'ifJ J6-1'001 angleso!
.hob wilh straig/u ga hes.
• IGEA!II nC!HN:'IlLDGY
con~entional
• MAY/JUNE
2003
37
_------------CUTTING,TOOiLS •••----------Discussion
Difference ill Wear at Leading Side
and T-railing Side CUttill.g Edges. In the
flank
case of gear skiving, the volume of metal
occur at !he trailing side. The rea on for
on the tooth surface removed
by the trail-
wear
at the trailing
side cutting
edges is greater than !hat of the leading
side cutting edges. Chipping
this may be ascribed
is also apt to
to the type of gash-
ing side cutting edges 'is almost the same
es given to the hobs used in me present
by the leading side cutting edges. However, it hould be noted
that the experimental results shown ill
experiments.
as that removed
Figures
8,. 9.
1.1.and
12
indicate
Although
there are two repre entative
types of gashes utilized
hobs, the straight
that the
type
is
for gear cutting
commonly
used
U
[Q)[ffio[j&%t®rn:oo
-Iprec:isi·onl
Cutting edge
'Y
E
th,rouglh dia.lmond ---
PI
P1
(a) Cireu!!lfete!!!lai section
PATENTED PCD R,EIIINIFORCING
FOR DIRECT PLATED IDR,ESS,E.RS
We will design,. build and gUBr.ant.eefrom vour gear summary charts gear dressers for
Reishauer SPA andl Fassler DSA Systems-Direct·Plated or Sintered·Bolld Sillgle- or
Dnuble-Sided Dressers.
Figure 17 Tool anglin, of .skiving .hob
witlt straigllt gashes.
WE also produce
gea r dressers: for
• Gleason lAG,
Gleason Pfauler
BI.GI'eas,on Phoenix
• Ueb:herr
Cutting edg.e
• kl,ingelnber,g
•
•
•
•
•
Oerlikon-Opa.1
Hoefler
Hurt
kapp'
Nilles
y
• Samputensili
• Mikronl
-Mug
• Csepel
We ·ofler our customers
• Highest Accuracy.
Competitive Prices
• Fastest Delivery-
Relap & Replating Service
PI
(a) Cireumfere.nlial section
Call Of fax us your gear dresser requirements.
You will quickly discover what leading U.S. gear producers have Ilearned.
W,,~
DR. KA'ISERgear dressers are the best value available'.
Distributed by:
S.l.Munson
& Company
3:8
MAY/JUNE
.
...
~ ...
L.
Pl
....
.
Y
PI
401 Huger
.St. IColumbia.
SC 29201
Phone: 1-800-175-13901'. Fax; 1-:803·929-0501
E-mail: [email protected]
2003 • GEAR TiECHNOLOG,Y.
www.geartechnology.com
Figure 18-Tool angks of .recommended
skilling hob wiJ11 a helica[gasl,.
• www.p·owertransmiss;on,co,m
•
III
-iICUTIING TOOLS-for
the
because
convemional
hobs.
the
of
accuracy
st.ra:ightga.shes
This
8° than that of the conventional
is
hobs
with
can be improved
with
flank wear of the carbide
'Of a
[Figures [6 and 17 show the geometrical
very high, as in the case of carburized
of the hob blade
ill the
gears (Figs, 8 and
Figure 17b show a sectional view of
the blade of a skiving !hob with cutting
edges on a right-hand helical thread and
with a straight-type
cutting
sides. This is easily realized by changing
the types 'Of hob
gear is
When
gashes.
the spiral
angle of the hob gashes is made equal
'9).
the lead angle of hob thread,
Method to Improve Tool Lives 0/
Sldv.ing Bobs. From the present experiments, it is estimated that the tool li ve of
skiving hob .
when a
to have the same
tool angles for the leading andtrailing
hob become
greater when the hardness
conventionalend
hobs can be increased
skJving hob is designed
with that of the hobs with helical gashes.
characteristics
skiving
The effect of the tool angle on the
co ts iII comparison
[ower manufacturing
carbide
hob with :9 = ()O.
mum tool angles
treiling
side
calculated
the maxi-
for the leading
become
the
from Equation
10
and
arne and are
3 (Fig. 18).
gash. The right-side
edge (trailing side tutti31g edge)
•
gives a smaller tool angle than that of the
left-side curtiag edge (leading
ide cutting edge). The greater the tool angle, the
smaller the chance of chipping at the cuttingedge.
The maximum
tool angle is obtained in
the section normal to the cutting edge. The
maximum tool <PL for the leadiag side can
be calculated
maximum
fram Equation
tool
angle lIl'r
side is calculated
l and the
for the trailing
from Equation 2.
where,
in .!'I, <II = (sin 11sin an - tan e/cos 11)cos o:.n
tan. 'TJ = tan H co an
tany= tan y Icos o:.n
Although
the
these equations
process
for deriving
is omitted, due to lack of
space, numerical
examples are shown as
In the case of Hobs F and G,
value (pre sure
angIe an = 20", lead angle of hob thread
Y= 3.6", relief angle E= 3.7",. nominal rake
follows.
ANI Systems Co. announces that it is now a
manufacturing source of spiral 'gear roughing:
and' finishing cutters and bodies.
when given geometrical
angle
81 =
30°)
areintrodllced
We also can manufacture new spiral
cutter bodies in diameters of 5" through 12"
at present.
into
] and 2, ¢lL = 98.7° and '¢IT =
91.4° are obtained. For the conventional
Hob B wilh 6 = 0° and E = 3.5°, ¢lL = 90.6"
and <i>r = 83.3° are obtained. These calcu-
Equations
AJIN can also supply roughing and finishing
cutters for mosI5'-12"
Whether ,iI's service or manufacturing', consider us as analtemative source for cutters
and bodies.
You'll be in lor a pleasant surprise,
lated values agree with tile measured ones.
for tool angles, it is
From the e value
clearly
understood
that
the
chipping
hardly occurs on the cutting edges of the
kiving
maximum
hob with
19
=
30" becau e the
tool angle i greater
diameter bodies.
i
NEWI ,Hob andShaper
is
dOW
available
al
'Cutter Resharpening:
AJW
Systems 'Cllmparr~
by about
WWW.pOW,Bf'tf'BIJ.smis.s.iolJ'.com. www ..geart.ecllnology.,com·
Royal Oak, Michigan 48067
Tel: (248) 544-3852 • Fax: (248) 544·3922
I
GEAR T,ECHNOLOG,Y
• M.AY/JUNE
11111111
2003
391
_-------------CUTTING
<Pt
=<Pr::: 90° + !l ¢I
(3)
When the given geometrical values
are the same a . those of the above mentioned example excepting for the gashes,
tool angle <PI.= $r'" 94.8° is obtained.
The author estimate that application
of coated skiving hobs with helical gashesis very important for finishing fully-
TOOLS,I~~~~~~~~~~~~~-
hardened carburized gears economically,
although with some increase in the manufacmring costs for the hobs.
A.dvQntages Obtained by Oblique
Cutting. When the skiving hob was
used, the side cutting edge conducts
intermittent oblique-cutting (milling) to
finish the tooth surface, as shown in Fig.
19b. Although there are some fundamen-
(a) FOI conventional
hob (9 = 0')
Tooth being f nlshed
(b) For skiving hob (9 = 30·)
F.igure 19-0blique
,'llIgle ofcutlillg
edges of the two different hab«.
tal investigations
on the mechanism of
the continuous oblique cutting (Refs.
9-10), many problems must be solved to
obtain effective equations 11mcalculating
change in the cutting force during the
intermittent oblique cutting, such as in
gear skiving. Moreover, there are practical problems. For example, the effects of
oblique angle on the amount of tool
wear, the shape of chips, etc. The authors
are conducting some basic investigation
to show the effect of intermittent oblique
cutting on tool wear and the finished
Precision Made - Cost Effective
accuracy us:ing a hobbing machine, and
One Statement with Two Objectives
the carbide fly tools with and without
Dragon Precision Tools from Korea.
coating. The results obtained will be
Noticeable Different. Clearly Superior.
published in the near future.
Cenclusleas
The present investigation was conducted u ing six kinds of carbide hobs,
and the following results were obtained:
DRAGON PRECISION TOOLS CO., LTD.
1. Induction hardened gears with a
Vickers
hardness of about 600 Hv could
Represented Exclusively in the USA by:
be easily finished by a carbide skiving
hob without coating.
2. Carburized gears with a hardness of
21135 lorain Road
Fairview Park, OH 44128
about 750 Hv were very dH'ficult to finFax: 440.331.0618
ish due to wear and chipping at the cuthttp://www.gallenco.oom
tingedges when skiving hob without
htIp:llwww. .....
coating were used.
3. When a carbide skiving hob with a
coated TiN layer of about 5Jlmin thickMAY/JUNE 2003. I[lEAR tE.CHNOIE.OGY
• www.gearteclmo#ogy.com
• www.powertransmission.com
GREG
440.331.0038
AuEN
CoMPANY
I
401
_
••••••••
II'cUnING, TOOLS
ness was used, the tool life increased by
a factor of 10 in comparison to the One
without coating.
4 ..The skiving hob with a coated layer on
the flank only was effective in increasing
the tool Hie, especially in finishing
induction hardened gear with a hardness
of about 600 Hv.
5.. The flank wear of the trailing side
cutting edge was appreciably greater
than that of the leading side cutting edge
when the hobs were used for finishing
carburized gears.
6.. The reason for the difference in the
wear isexplained by calculating the difference in the maximum tool angles of
the leading and trailing sides (Fig. 17).
7.. It is estimated that the tool life of a
skiving hob to be used for finishing fully
hardened carburized gears can be
increased by introducing coated hobs
with almost the same tool angle for leading and trailing sides.
8. The tool angles for the leading side
and trailing side cutting edges become
the same value when the numerical value
of the spiral angle of the hob is made
equal to that of 'the lead angle of the hob
tooth thread.
Acknowmedgments
The authors express their thanks to
the engineers of the machine shop at
Kurume Technical College for their
assistance in this iIlvestigation.O
---------------
Hobbing" Wear,. No. 655, 2001, pp. 45-53.
6. Matuoka. H. and Y. Tuda, "influence of
Coating Films on Behavior of Crater Wear of
Hobs in Dry Cutting," Transactions JSME,
Series C, Vol. 67, No. 656, 2001. pp. 267-273.
7. Bouzakis, K.D" et al, "Gear Hobbing Cutting
Process Simulation and Tool Wear Prediction
Models,"
Trans.
ASME
Journal
of
Manufacturing Science & Engineering. Vol. 124,
No. I. 2002, pp. 42-50,
8. Sakuragi,
I., er al, "Carbide
Hobbing
Technology for Automotive Gears," Journal of
the Japan Society for Precision Engineering,
Serle C, Vol. 67, No. 655, 2001, pp. 221-226.
9. Stabler, G.v. "The Fundamental Geometry of
Cutting Tool," Proceedings of the Institution of
Mechanical Engineers, London. Vol. 165. 19.51..
pp.I4-26.
10. Sharnoto, E. "Study on Three Dimensional
Cutting Mechanism. (lst Rep.)." Journal of the
Japan Society for Precision Engineering, Vol.
59, No.3, 2002, pp. 408-414.
Take.ii Sugimoto
is an associate professor ill the department of
mechanical engineering III Kurume Institute of
Technoiogy in Kurume, Japan. He has more than
25 years of experience in gear manufacturing
and is a member of JSME, JSPE and the Japan
Society for Design Engineering.
Akira Ishibashi
is a professor and head of the graduate school ill
the department of mechanical engineering at Soja
University in Kumamoto, Japan. He has more than
40 years of experience in gear manufacturing. He
was awarded for his research all gear grinding
machines by !SME in 1970 . Ishibashi is a member
of !SME. JSPE. Japan ASME. Society of
Tribologists, Society of Automotive Engineers of
Japan and the Japanese Society of Strength and
Fracture of Materials.
Masataka Yo:nekura,
References
1. Ishibashi, A .• S. Tanaka. and S. Ewe. "Design
and Manufacture of Precision Gear Grinder with
CBN Wheel and Load Carry.ing Capacity of
Gears Ground," Bulle/in of JSME. Vol. 28, No.
238. 1985.pp. 718-725.
2. Ishibashi, A., S. Tanaka, and S. Ezoe, "Design
and Manufacture
of a C .C Gear Grinder
Capable
of Mirrorlike
Finishing,"
JSME
International Journal, Series
Vol. 33, No.2,
1990, pp. 245...:250.
3. Ezoe, S. and A. Ishibashi.
"High-Speed
Mirrorlike Grinding of Precision Gears U ing a
Trial Gear Grinder
with a CBN Wheel,"
Proceedings of JSME International Conference
on Motion and Power Transmissions, 1991, pp.
207-212.
4. William. E. Loy. "Hard Gear Proce sing with
Skiving Hobs," Gear Technology, March/April
.1985, pp. 9-14.
5. Rech, J .• M.A. Djouadi, . and 1. Picot. "Wear
Resistance of Coatings in High Speed Gear
is a professor in the department of mechanical
engineering a! Kurume National College of
Technology, a technical school established by the
Japanese government, He has more than 30
years of gear manufacturing experience and is a
member of JSME and JSPE.
Process Gear has been a.
leader in the custom gear
industry since 1942. Process
Gear is capable of producing
parts up to AGMA Class 12
with the documentation and
process control that comes
with M&MO Precision Gear
analysis. Customer applications range from power
transmissions, construction
equlpment, HVAC, hydraulic
pumps and printingl trade
equipment
Bengal .'ndustries is a
precision custom injection
molder speclallzlnq in gears
and engineeredplastic parts.
Bengal serves a. wide variety
of markets including automotive, medical, industrial,
HVAC and children's products.
Process 'Gear
3860- T North River Road
Schiller Pam, IL 60176
(847) 671-1631
Fax (B4T} 671·6840
W'IIW.processgear.com
Bengallindustries
11346 53rd Street NoMn
Clearwaler.FL33760
[7(7) 572-4249
~ax(727) 573·2428
\Y'IIW.bengalinduslries.«Jm
m
mtact: jhe'rl'l@processgeauom
Tell Us What You Think ...
Visit www,'IBrttchnalagy.comto
• Rate this article
• Requnt more information
• Contact the article mentioned
• Make a suggestion
Or call (8411437-&&04to talk to one of our editors!
www.poweruansmlssion.com.
www.geaf.tec.hnology.com.
G,EAR TE'CIlINOUlGY.
MAY/JUNE
2003
41
_------------INDUSTRY.NEWS
KUngelnber'g.AIW Systems form AUisnce
Klingelnberg
Oerlikon Technology
Center (KOTe) of
Saline, Ml, joined forces with NW Systems Co. of Royal Oak,
MI, to provide spiral bevel and hypoid bevel tooling and tooling
technology services.
KOTC and NW Systems will provide cutterheads, blade
sticks, finished blade grinding and gear cutting technology services to the U.S. gear manufacturing market,
According to AIW Systems' press release. the strategy is to
offer locally a comprehensive product line of cutting tools with
application engineering expertise and cutter sharpening services.
Mitsubishi Giear Cen1er Panners With !Balzers
The Mitsubishi Gear Technology Center of Wixom, MI,
teamed up with Balzers lnc.'s Wixom Coating Center to provide
local coating service for Mitsubishi brand hob cutters.
Previously, Mitsubishi's coating operations took place in its
Addison. [L•.machine tools facility under the name Mitsubishi
SuperD.ry coaling. After econo~c consideration, the company
decided the Balzers BALINIT
FUTURA NAND coating was
of the same quality. Also, with Balzers' nationwide coating cen-
II.
_
ters, large batch runs and strict quality control, Mitsubishi found
thatit was not cost effective to compere with Balzers, according
to Mitsubishr's newsletter.
Schafer Acquilres Chioago Gear Works
Schafer Gear Works of South Bend, IN. acquired the assets
of Chicago Gear Works of Cicero, IL.
Chicago Gear Works was a major supplier to industrial manufacturers and Schafer hopes this acquisition wiU increase its
manufacturing capacity with bevel gear and worm gear technology, according to Schafer's press release.
Chicago Gear's manufacturing operations have been moved
to South Bend and ilS turning operations to Schafer'sprecision
machining plant in Fort Wayne, IN.
AGMA Releases INew Information Sheet
The American Gear Manufacturers Association (AGMA)
released an information sheet called Accuracy Classification
Syslem-TG11gel1tial Measurement
Tolerance Tables for
Cylindrical Gears.
The publication provides inch and metric tables of the 101er-
T'he World of H1ardl Gear Finish.i.
l
H'onin
Broach
Customised .solutions
Fassler Corporation, 131 W. Layton Ave., Ste 30B, Milwaukee, WI, 53207-5941 U.s.A.
Phone +1 (414) 769-0072. Fax +1 (414) 769-8610, [email protected]
www.faessler-.ag.ch
42'
MAY/JUNE
2003 • GEAR UCHNOLOGiY.
www.geartechnology.com
• www.powertransm;ssion
..com
I'NDUST1RV INEWS
_
ances dealing with tangential measurements of spur and helical
gears for the different
accuracy
grade
explained
in
ANSIIAGMA standard 2015- ]-AOl.
According to the AGMA new letter. the sheet was developed
to supplement the information contained within the tandard,
While the tables may be used, to e timate the tolerances for an
individual gear. the actual tolerances hould be calculated and
rounded according to the formula of the parent standard.
Custom. Bevel Gear Mfg.
Per your Sample and/or Blueprint
1==1&11=-==_==----::----:__
Machil1e ami Gear CorporaUon
s. 1)q,vid
G<!llIa!l!
Spiral Bi
.~.: 66" PD
Straight Bevel Gears:~ 80" PD
Spurs,. o,elicals, Spline Shafts
Gearbo-x Repair
Heat Treat RacUfty In-House
S. David Graham was named general rnanager of the cutting tool division at General Broach
Co. of Shelby Town hip, MI.
Since 1993, Graham ha worked as national
sale manager of General Broach. Prior to that, he
held the position of both chief tool engineerand
eng ineeri ng manager:
Among his new responsibillne
will be developing
alliances with broaching partner in Europe.
-111
Shl!ron. TN
New Ge:neral 'Malnager at General Brloach
I
Spec
1-800-.238-0651 - Fax 731-456·3073
email.: inquirYJ;lt@brJ;lear;coD1
website: www.bn:ear.com
CALL FOR BROCHURE
strategic
Philadelphia Geair OHers Western G,ear,WesTech
IRenewal1 Parts,
Philadelphia Gear Corp. announced the availability of genuine
renewal parts for Western Gear and WesTech gearing units.
The company acquired the brand Western. Gear and WesTech
in 1996 and is the only proprietary ource for tho e parts, according to the company' press release. Wi.1h these units, maintenance
engineers can have their We-Iem Gear and We Tech units e:rviced using genuine pans instead of re-engineered one .
In addition. Philadelphia Gearcan provide original drawings of
Western Gear anel WesTech gearing units, Digitally scanned versions of these drawings and bill of material will be avail able at the
company's five regional service centers by the end of 2003.
JIE,IIIIL
-SOUTH,
KOREA
150 up 10 11,800'mm dia ..
Geolr H!obbin'Q Machines
Conventlonall. NC & CNC
Solid cast iron. rigid and durable design. GE
- Fonuc controls ... high quality at a great value
- more than 270 machines installed in the USA
New Plresident. Expa,nding f,aciJi;1y for
Machiine, 1001 Sy-stems
Jerry Rex was appointed
president
of
Mentage
Inc.'s
sub idiary Machine
Tool
Sy tern (MTS) of Charlotte. NC.
According to the company's press release,
Rex ba 26 years' experience in metalworking
and in the application of machine tools to manufacturing prooe es. Currently, be chairs the
Machine Tool !Engineer Certification Committee
of the American Machine Tool Distributors'
Association
(AMID'A).
In other new , MTS announced plans to con olidate operations from Georgia and South Carolina into an expanded
Charlotte Technical Center.
1imk.en C'ompletes: Torrington A'cquisit,i'on
ASI Machinery Co .. Sole Importer to USA& Canada
SI6-D River Highway #200 Mooresville. NC 28117-6830
Phone: 704-528-0902 • Fax.:704·528·0900
E-mail: [email protected]
The Tirnken Co. of Canton . .oH,. announced Feb. ]8 the comwww.powflrtransmiss;on.,com
.•.www.{JflBr.re.chnology.como
GEAR: TECHNOLOGV
• MAY/JUNE
2003
43
~------------------------------~~------~~--~--____
I
plenon
IINDUSTRY NEWS
of its purchase
_
of The Torrington
Co, from Ingersoll-
Rand for $840' million.
Of the $840 million, $700 million was paid in ca h and the
remaining
$]40 million was in Tirnken shares.
According
press release.vthis
to the company's
was the largest in Timken's
history, increasing
50 percent and making it the world's
pany, with an expanded
bearing-based
portfolio
acquisition
size by
Timken'
third largest bearing com-
of automotive
and industrial
products and services.
The Timken
and specialty
Co. manufactures
steels and provides
engineered
bearings,
alloy
related services.
'New IPowder Metal Company ,in Pennsylvania,
Vision Quality Components
ulate
Spi~al&. Stmight Beve'I'Gear M'anufacturing.
'Commercial to, airc~aft quality gearing.
Spur,.helical, spline~ shafts, intemall Be eXlemaI,
shaved & grou-nd g.ears. Spiral beve'Jgrinding'.
Midwest 1iransmissions & Reducers.
ISO compliant &. AS 9UIO compliant.
material
structural
is a new manufacturer
and multilevel
transportation,
industrial
new company
is a continuation
Rochester,
and consumer
WJ!!T
=r-
• .••
~
.'
[email protected]
The company's
capabilities
200 tons, sintering,
steam
as vice president
Vibratory
according
The only proven resource for gear manufacturers
who want new business
and their dealer networks.
to its pre s release,
.oH.
The plan is to combine
SMW's
steady
rests
with LNS's bar feed! products to major turning machine GEMs
With the alliance
al and automatic
LNS America can provide turnkey, manu-
steady rest packages
that include base systems
and brackets, according to the company's press release.
SMW is best known for its precision workholdlng devices.
to,
In Memoriam
a gear machinery
March 8 after
specialist
a. long
located
in Hilden,
illness.
I.
Sign up, online or call (.a471~7·6604to find out more about
I how powertransmission.com™ can work for your company.
powenrensmission. com™
1425 l.unt Avenue, Elk Grove Village, IL 60007 USA
Phone: (847) 437·6604
Fax: (847) 437-6618
E-mail: [email protected]
2003 • GIEAR IECIINlllOGY
PA.
of power chucks located in
Joining powertransmission.com™
is fast, easy and
relatively inexpensive. Being listed costs just $1,195 per year.
MAY/JUNE
20-
fini hing, CNC
with bar feed supplier LNS America of
Cincinnati,
With nearly 150,000 paqe views and more than 30,000
visitors per month, powertransmission.com™
is tbe premier portal for generating, new business.
44
of
and Robert Aleksivich
Marlis Tetteroo, of Teco Werkzeugmaschinen
!
This
Metal
range from pressing between
treating,
a manufacturer
IL, partnered
puwertransmission.com
more than 11,101001sales leads
our advertisers in 2002.
Powder
of Vision, which is located in Clearfield,
SMW Autoblok,
Since 1997, powettrensmission.cont» has been hel,ping
gear manufacturers find new customers.
for the
markets.
SMW Auiobiok Panners wi~h lNS America
Wheeling,
We delivered
of Innex
Dennis Johns will serve as president
CONTAC1
CRAIG !D'.ROSS
\5861754-8923
,FAX(:586) 754·8926,
components
product
NY, whose assets were purchased! in January.
turning and double disc grinding,
M.IDWEST. GEAR ~..
lit TOOL. INC.
12024 E. Nine' Mile Road
Wa~ren, IMI48089
of partic-
Tell Us What You Think ...
Visit www.ge.nechnology.comto
• Rate this column
• Request more information
• CORtaerthe companies mentioned
• Make I suggestion
Or call (841) 431-6604 to talk to one of Our editors)
• IWlWw.gesfleclJno.logy.com
.. 1W1W1W.power.trafismissio.n.com
GmbH & Co.,
Germany,
died
----
CLASSIFIEDS
-----
SERVICE
,
(7!1"1---,-"-"I~
...t
...r;
-
' ~
-
WHEN IT HAS TO BE RIGHT
•
• BROACH SHARPENING
---------------
• GeM G.rl!ldlng to' '94'
• HOB SHARPENING
Ground loath gallI'S· ,and
IPiniDOS ta 1 D.P; and up to
A.G~MA ,qualilJ class 12
"industrial ,Gearste 250·
• J\Jrbo 'Compressor Gears'
• SHAVING CUTIER GRIND liNG
• THIN FilLM 'CIQATING
I
• CUllo!'!'! Drivel
• Spline Broaching
• GlIar Metrology
• Stock IPlanetiry S,~
• CUSTOM HEAT TREAT SERV,ICE
PICK UIJ ArW o ELI VEln' If,j MANY AlllAS
•
Reduce,.
9£t:,\;JBO ...{ .H~PJ,\Jfj
Custom Gear Services Sim:-e 1946
-----
--------------
IISO-!lOO1
I
lll'D
IWP:O
'1r
!I"
",.D
.. PJI
1115"
14"
-I!--'~
MlDWaft..,..
Gleason
I
•
I
TOols
COR P ,0 R AT ION
lDJ'
The Gear Works-Sealll!!.
Inc.
500 S. Portland Street
Seattle, WA 98108-0886
Phone: (206) 762·3333
:Fax: (206) 762-3704
IE-mail: [email protected]
1351 Windsor IRoad
loves Park,IIL 6111111USA
IPhone: 8115-871-8900
Fax: 815-877-0264
~'.
2182 E. Aurora Rd.. Depl MG, twins IUgIDR 44087
Nlon.: IIlIII m..u19·' IFu: '(3311)~_
www,-m:wg,ucom'· E-mail:s.LI@nrwg~
Website: www.gleason.com
E-Mail: [email protected]
Iinduction HI,alrde'nin:,g
SiharpeninlgServie,e
S;pecialisls in Tooth by Tooth
Contour IHBlrdening at Internal
Spur, h"ical and lJ,velgears
Our gear hardeningl 'equipment
includes, !5 NATICO sublmerged
process machines and 5 AJAA
eNe-contmlled
'g,ear scanning:
machines. Tooth by tooth gear
hardening from .5Il)P-10Il)P; up to
15 tons, 200' diameter.
A_merleBnMe1alTreatingi Company
llil vel nd, Ohio
Pholle: (216),431-4492 • IFIl~ '(2161431-15081
Welle www.llmeric.llnmetl'lll1f1IJJing.cam
E~mail: ,lImc" IImer.iCBf1mBtB/tr;flBlif1g.cam'
IBrea'kdown S'ervice
Rates-Lme
Available
~.
'for hobs, Iminingl
*GOLD
insertion, Additional
:5200P,ra'''. Stone Parkway, Suite 100
HQffm!!~ Estate$, IL 60192
tal.: (8-47) 649'-1 "50 - IFax: (8-47) 'M!I.(J,112
:2083 W.M-!s!i, West Branch" MI 4B661
1-888-Rnharp
1'-888-737-4277
ial.: IIIUi) 345 -2865 - Ihll.: (989,) 3415-566(1
15aD Progrllll
Dr;" RIchmond, IN 47374
"al.: (765) 935-7.t2A - IFu: 1765)'!l35-7631
per inch: IX-$255,
per insertion for color. Gear Technology will, set type 10 udveniser's
accompany
Technology,
classified ads, Send check drawn in U.S. funds Oil II
31
Gear Gnnders
• Gleason TAG 400 eNC, a-axis
High Production Gear Grinder
• Full ONC Multi-axis Cylindrical
Grinding (Internal and External)
• High Performance CNG Hobblng
'. Continuous Process Improvement
Utilizing SPC and Quality Planning
• JIT Delivery using Innovative
Stocking Programs
800-441-2392
F,ax: 716-1174-9003
www.nlagaragear.com
emaIl;infoinlagaragear.com
per inch). Displil)' Cia sified: 3" minimum:.X-$73S.
per insertion, 6X-$225
per insertien, Color Closslned:
layout or design. a classified ad UI no extra charge. Payment:
.S. bank or VisaIMusrerCardlAmericlinExp.ress
P:O. Box. 1426. Elk Grove Village" II.. 60009. Agency Commission:
must be reel: ived by the 151.1:1
of Ihe month, two month
men!
3X-$215
.""'"
• ReiShauer RZ300E ElectronIC
STAR COAnNGS
lines 545 per line (8Iin~
• Spur, HeliCal and Pump
Gears to AGMA Class 15
• Featunng the latest grinding
and CNe teChnology Including:
I~-
eli1!>~lfied: I" minimum, $325. Additionul
per insertion, 6X-S645per
cutters
,s'hap_r cutters" shavlngl cutter.
(I
agency cemmisslon
3X.~685
Add Sl:50
Fun paymenl. must.
number and expiration dale to GM'
on classified ads. 1\'1.le:l1ial!iDeadllne;
Ads
prior to publ ication. A'ccepl nee: :Publi:oher reserves the right 10 accept or rejeci advertise-
hi discretion,
www.polNertrallsmission.com·.WWIN.968rt.ecbnology
.•com • IGEAR UCHN'OLOGY
• MAY/JUNE
2003
45
-
-
-
*
(763) 425-5247
*
THIN RLM COATINGS
HSS & Carbide up to 5" Dia.
Straight Gash,
Sharpened & Inspected
Per AGMA STANDARDS
Equals, Serious Downtime
But We
can
~J
-!>y-~
on
pt'Ii!IC:IiiIOf hob9
can
----
. -
be
~
.... ~ __
(J/'~...-y
_ _---..-
_".,.".1ooI1IIL
We know ygu. ~
)I'Ol.iIi" tc:OtI b8ck ~'''I:eflmfriUung
__
81'<! b.!ned '" ,.,.....or.~0ri9ina1
~
~,.,...,.
... _
.....
__
~In....~
..
...
~\ I , I
f
~:
[email protected]
\
...... Hob Recondltlonlng,
o!!WO.8D5A82'7"
21f35
l.tCiiRAJN
ROAD
-1'!!It.X:
-
.....u .331"05
1
PARK.
...
0fit0 44,:d
WWW.OAL.LNCO.COMI
t-"'-l
I
I
Your best choice
,in oITthe shelf
ASH
«:
.~.
IINTERSTATIE. TOO,L CORP.
CLEV~OHIO
gear I.ooling
"".SIV:
CUSTOM fNGINEERED&
MANUFACTURED CUTTING TOOLS
ESTABUSHED '960'
Ash Gear & Supply
Our experienced sales staff is ready 10 match
your gear toolin& DCCd5 ID a product on our shelf.
wbeIbcr it is a hob. shaper, broach, 104 bevel
aenerator or single cutter.
We stock Premium MalCriais. Class AA-D.
and Special Coatings.
Wid! 35,000 sq. ft. of gear cutting IDOls for
SALE or RFNT you are SIft ID fiod AGMA stancbrd 85 well as urnque IOOIing 10 cut your job.
Give lIS a call at 248-374-6155
Fu us at 248-374-62S~or email us at
[email protected]
.ashaear.rum
\I \1 \\
,HOBS)
.. FAIR'VtEW
---
--
--
-
IiIIIm.uB &1m""*ID.E•••
Gear HOOI!eIs, Fdows Shapers, Gnndels,
HOB Chetkers, Shiper Cutter Checkm,
Inspection Systems and Lead
" IlnvolutB Masters
--
-
8aJber-Colman HoIlbels, Fdaws Shapers
and RoIo- TI!CI1noIogy Inspec;boo SystEms
NRTIIIEIIVa
.•Bourn " Koch. Fellows, Barber-tolman,
RaIt'I- Tecbnology.FelillSOIll,J & l
• RecaIlbfatlon lit Your Gear Inspection
System.wd
& Involute Ma&t8rs
• Gtar InspIdlon IiHOb Sharpening
precision. affordability· value.
TYPE
IDP
Slt.alght Bevel
SpirallBevel
72-2
FORM RELIEVED &: P,RORLE GROUND
MIWNG CUTTERS
GEAR SHAP,EA&: SHAV1NG CUTTiERS
AU ICLASSES OF IHOBS
HSS,SOUD CA_RBIDE 11 CARBIDE npPED
WHETHER VQU NEED NEW TOOLS,
MODIFICATIONS, RESHAAPENING,
REPAIRS OR M&M INSPECTIONS.
CONTACT US FOA A. QUOTE TODAYI
WWW.inflrst.fltoolcor.com
Tel: 216-&11-10'77" fax.: 216-&11-'5431
Call our localropresentative:
Contact: Mr. Amar lPai
Ph: 925·285·3926
Fax: 425-952·9914
Email: [email protected]
www.Bccusplrals.com
• CmURACT METROLOGY SERVICES
• CURVIC COUPLING G!I=!INDING
& INSPECTION
• BEVEL & CYLlfJDIlICAL
DEVELOPMENTS & PROTOTYPES
• APPLICATION ,ENGINEERING
SUPPORT & DESIGN SERVICES
• HEAT TREATMENT
SPECIALIZED GEAR SERVICES
The Gleaso:n 'Works,
1000 UniVer.;.ity Ave.,. P.O. Box 22970
Rochester:, INY 1'489:2-29701 U.SA
Phone: 5851473-1000
Fax.: 5851481-4348
IE.-mail:[email protected]
www.gleasonl.com
Precisionl SpUn. Grlndln,gi,,;SIrvlev
f!cllrospac,. Comm _RJaJ. De"ns,
Splints a 6nrl lint. a Ext.
·Tiapm-9<IArbors
.•SftIon,
-T!mIIJg'/!:m:,
• Spl]M· Gaga
"Hllm'
·$PrLIH!' tollWb
·khr!!pPt~pCHI
• Hltllli Etdl
··Wftp-Oab
•Crowns
-SInd
GlGn
.I"fit HiM lim Rnf.I:yI'1
·H&M !LIJ~tll:1!!,l'Im•
MACHINING
fAX (586) 323-9069
MAY/JUNE
2003 .• GEAR TECHNOLO,GY
• www,g.esr,tfu:.hnQtogr.c,o.m·.
CO
Now offering t.l1efallowing services for:
Broaching Machin ••
Gear Shaving Machin ••
Rack. Roiling IMachln.a.
IUO
• Redesign & Retool
• Replacement Parts for Red Ring,
National Broach and Nachi Products
• Repair Services for most gear and
spline-making
·604'7 18 Mil_ Road
Sterling He~gh ,MI 48314
I'H (586) 323·9061
TECHNOLOGY
•. Repair Services ln-plarrt
WlMorI Jobs .(:1/1" lDk!nmorr)1
·IIIPage (lIa-rtlnSiI em Form, Lead, Inda"
NACHI
Contact:
46
D1A lIn~
0.25-21'
0.25-211
72-3
Helical Bevel
5O-e
0.25-5
Spur & Helical
0.25-32
50-3
Worm Wheell
50-3
0.5-20
Micron
76-25
0.25-2
con/scI us for ill detailed product brochure
ACCUS!PIIRALS
IlndeXTaChliOIOg'a
.."'.1'
9530 - 85TH AVENUE NO.
MAPLE GROVE, MN 55369
----
I Precision gear cutting services available
as per oustomer's drawings &, specifica·
I
tions al compermve
rates per AGMA
I
STANDARDS.
Help ...
~)'OU"",,"-,y
i1"IfIkBs
KORO SHARPENING SERVICE
------
GEAR CUTTING
I.
You are weill aware lhallHobs are,
assels.lhat need 10be m
".,.
Qulclt Tum.muM
-
SERVICE
--
ID'ULL, HOBS
HOB SHARPENING
--
machines
Lee Watson
watson [email protected]
ph: 586.263.0100
n<: 586.263.4571
www.nachimtc::.com
www ..powe.rtr.ansmi.ssion.,com
,
\IVEBSITES
IEVER,YTHIIING
B'UITTHIE
IB,UILD'ING
._-::::=t~_
---.-,
NIIAGARA GEAR
'I1Ie NiaprI 0IIr WwhIite dotai1I our pNOl- I
SlOG poGDd epur. be&aI ud pump .....
AD our pili"
maaufacturod wbh _ IIIIII ... ariDdiDI tecluIoIotY The ...,
., pnwideI iIIformaIioo on NiIpra Ow
campIeIe c:.pabilibel 10 meet your !DOlt
cIeIDudiq. clole toIenuc:e reqlUmDlDtl
widl rut tumaroaDd
The Gear Industry Home Page™
Get AIiVour 'Gear Manufacturing
Equipment And Accessories
Through Our Website
www.niagaragear.com
o Machines
o Tooling
_---...._-=::-..;~~
o Services
==~--"'_'
.---.--_---.
o Software
Get Everything Needed For
Manufacturing Gears
Visil
www.ge.anech.lJ%gr·coffl.
Today!
Attention: Readers Outside the United States
Get The Electronic Version of
Gear Technology FREEl
(OIIIplete ISSle5-
AD Articles, AI Ads, AD DepcwhHats
'ou1i
-Are Available Onhne
Through E-GT.
U. AdIDbII "aab.It
......, 4.0 or.."... VDIU
I"tIIMf
lUi........
Cjj'i, ~
tM
.t ... '....
ian..... far".
CQtjij.
"",-a-~.
DoWnJc!1d1 WI'!!!I!I IH!MJ
., D ,r d. "'-""
It. ru MIA
(JOI'J"-..........
-..
.£(IT,""'
_
"""""-,,,.......
------ -
Subsaibe Today To Gel
'''''''1.,..
MagazIIe FREl
Useyour subsaiptiolcardor visit www.,...,...,.".coa
..
~----------------~~--~~
~
-~
DoWnIoId
.."'r..._
.. s-Ho)
Ilry Mdl!!n
~-)
www.powfI"ransmiss;on"com.
Gecr
www.!lurtechno,togy.,com
• GEAR TlECHNOLOG,V • MAY/JUNIE 2003
41
I,
AIDUE.NDUM
_
A Bieye e with REAL Gears
he Addendum
team was ill
Chicago in 'early March. for the
National Manufacturing Week
show, when .it saw something
unusual: a bicycle with gears. Real gears.
Spiral bevel gears, in fact.
The mountain bike was .at Suhner
Manufacturing's booth. on a small platform, The bike was on loan for the show
from its maker, Christ:ini Technologies
Inc. of Philadelphia, PA.
Suhner was feamringti1e
bike
because it manufactur-e the bike's three
spiral bevel gear sets for Christini.
Now, the Addendum team knows regular bikies don't have gears .. Being gear
goofs, we've known for years that reguIar bikes' "gears" are really sprockets,
So, why do Christini bikes have real
gears?
Because they're all-wheel-drive bicycle . Power can move back and forth
between the bikes' wheel via a. drive system. and the gears are part of that ystem.
Starting wi!h the rear wheel, the ystem has a spiral bevel gear (92 mrn 0.0.,
45 teeth) and pinion (30 mm D.D .• 12
teeth) (hat are opposite the bike's sprocket assembly. Thi gear set. connects to a
drive shaft, which itself runs through the
bike's rear suspension, From there, the
drive system goes inside the bike's
frame, in the top tube (the horizontal bar
between the seat and handlebar).
4:B
a distance, the
goaredl drive systeml
blenlls imo'ihis moltntaln bike.
MAY/JUNE 2003 • IGE.AIRUCIIfIN:'lnOGY
drive shaft runs inside the top tube to the
head lube. where the handlebar is mounted, In ide the lube is !he system'
econd
piral bevel gear set, two miter gears (34
mm D.D.,. ]5 teeth each).
Amird drive shaft runs down the front
fork to the front wheel's hub and connects
to the third spiralbevel gear et, The hub
is a zero-backlash freewheel hub with a
roller clutch mechani m, The gear set is a
piral bevel gear (83 mm D.D .• 48 teeth)
and pinion (26 mm O.D., 1,2 teeth). Also,
the e steel gear sets have a coating
impregnated with Teflonlll lubricant.
The bikes' overall ratio is about
,0.94; I (rear wheel to front w.heel) ..
'That's the magic of the drive sy tern
right there." says Steve Christini, president of Christini Technologie and inventor of the drive system.
The rider drives the system so long as
both wheels are rotating at the same
speed. The slight gearing differential prevent power from being transferred
between 'lhe wheel .
If the rear wheel slip, ir'll spin
fasterthan the front wheel. At this point,
the system engages and transfers power
from the rear, faster wheel tothe front,
slower one to bring them back in sync,
As Steve explains, the drive sy tern
won't allow the front wheel to go lower
than. the rear wheel.
The systemtransfers
power to add
traction, so it helps riders maintain control when they're riding over wet roots or
slippery rocks or whenclimbing
a slippery grade.
The system weigh 2
pounds 1] ounces and is
engaged with the flip
. of a switch on the han, dlebar. When it isn't
engaged, the bike rides
like a reg-ular mountain
bike.
• www ...yearfeclmolo{Jy
Look clDse, (with I hel,pingl handl and WDu'l1see
this lIike has I :spir Ibeval gear Iindl pinlDn~.ln
'Itt. the bike, has Imea spi ralbevel gear selS.
Steve came up with the idea for his
system when he was riding his mountain
bike in a. park. tIying to climbs muddy
slope. While hi rear wheel wa lipping
and sliding, Steve had the first, often exasperated, though I. of invention-v'There
must be an easier. better way to do this."
nun was the summer of 1994, before
Steve (a mechanical engineering major,
of course) graduated from Villanova
University. That next school year, Steve
developed hi idea into a prototype for
IDS senior deslgn project
fu the ummer of 2002, Steve's sy tern became commercially available all
his all-wheel-drive mountain bike .
For National Manufacturing
Week.
Steve made one of his bikes available to
Joe Agro, field sales manager for Suimer.
located in Rome, GA.
Suhner's interest-and
the Addendum
team's interest-in
featuring a Chri tini
all-wheel-drive bike was imple,
"II. was a unique apptication for spiral
bevel gears," Joe says. 0
Tell Us What You Think ...
Visit www.g.'t1tchnology,comto
• Rate this column
• Request more infolmlltion
• CCHJtact the organizations mentioned
• Make I suggestion
Or cell 18471437-&604 to talk to HI 01 our
editors!
..com ., wWW.,pow8ftransmissioIJ.com
•
Ine
www.pe·rygear.com
Perry Tecilno,IDgy Corporation
E-Mail: sale
errygeQ~co.m
Phone: f8,60) 7.38-2525
FIIX.~(8'60)' 738-2455
p.o.
YOU"I'1'
Box 2J 129 Lndu.sll'iaJ PD,i ROlld
only a clirk uw.ay from..
The ear
pline xpert
New HllnlonJ"
ex
060S7
Shave
with the
experts
When it comes to shaving" nobody beats our quality.
lit is a.well known fact that the accuracy of the shaving
cutter serration plays a very important role lin shaving
cutter tool life' and workpiece quality:
Apart from exoellent base materials Star-SU uses
custom-made shavingl cutter serrating machines for this
process. The accuracy of the serration pitch and depth
Is one of the reasons why our shaving cutters are the
choice of manysatisfiedl customers in the US and all over
the world.
To maintain this superior quality and to meet your profile
requirements like tip and root relief, crowning and
other variables, we, offer shaving cutter regrinding
services in our Hoffman !Estates serv,ice facility where
we 'have the latest shavingl,cutter ,grinders available on
the market.
Not onty are we experts in shaving cutter applications
but we also offer a complete range of gea,r cutting tools
for hobbing, shaping, grinding and chamfering-deburring
as well as master gears.
--
Can us. We',re closer than you may think.
~
~I
YO.-ur QI.IObal sourc..e'
for' Igear tlechnol~ogy
Star-SIJ Inc.
520(1 Prairie Stone PS5kway
Suite 100
Hoffman Estates, Il 60192
Tel.: +1 (847) 649-1450
Fmc +1 (847) 649 ..0112
sal'es'@sta.t·su.com
Star·SIJ Inc.
23461lndListriaJ Park Dl1ive
Farmington Hills, MI 48335-2855
leI.: (248)474-8200
FIDC(,248) 474~9518
sal'es@star·SIJ.com
.www.star-su.com