DYNALOAD - design, construction, use and maintenance

Transcription

PNEUROP Publication
DYNALOAD - design, construction, use and maintenance.
Contents
Foreword ............................................................................................................................................................2
0
Introduction ...........................................................................................................................................2
1
Scope .....................................................................................................................................................3
2
General ..................................................................................................................................................3
3
Relationship with standards...................................................................................................................4
4
Design....................................................................................................................................................4
4.1
Preferred sizes ..........................................................................................................................4
4.2
Anvil and Test tool ...................................................................................................................4
5
Performance/Power measurements .......................................................................................................6
6
Operational features...............................................................................................................................6
7
Maintenance ..........................................................................................................................................6
8
Construction ..........................................................................................................................................7
Table 1 – Identity of component parts as shown on diagrams in Annex A, B, C and D.......................7
Annex A Type 1 - Single piece square-end Dynaload .......................................................................................8
Annex B Type 2 - Single piece taper-fit Dynaload ............................................................................................9
Annex C Type 3 - Cup/Ball-end Dynaload ......................................................................................................10
Annex D Type 4 - Needle scaler variant Dynaload..........................................................................................11
Annex E Design and Constructional Details ....................................................................................................12
Table 2 – Bottom plate specifications .................................................................................................12
Table 3 – Cylinder specifications ........................................................................................................13
Table 4 – Stud specifications...............................................................................................................14
Table 5 – Anvil specifications.............................................................................................................15
Table 6 – Bush clamp plate specifications ..........................................................................................16
Table 7 – Flange specifications ...........................................................................................................17
Table 8 – Guide bush specifications....................................................................................................18
Table 9 – Steel ball reaction plate specifications ................................................................................19
Table 10 – Steel ball specifications .....................................................................................................20
Table 11 – Type 1 toolpiece specifications .........................................................................................21
Annex F Recoil spring......................................................................................................................................24
Table 14 – Recoil spring specifications...............................................................................................24
Bibliography .....................................................................................................................................................25
1
Dynaload Publication/Version 1.2 – Oct 2005
DYNALOAD - test device for percussive tools - design, construction.
Foreword
This publication was produced by a working group of the PNEUROP Tools Committee. The information
provided is primarily intended to instruct and supplement guidance given in standards for the measurement
of noise, vibration and performance of percussive hand-held power tools.
At the time of publication of this guidance document, dynamic loading devices, such as the ones described
herein, had been used for many years in conjunction with the testing of percussive power tools. In particular,
the vibration test codes, ISO 8662 parts 2, 3, 5 and 14, all specified the use of such loading devices for
testing a range of power tools, including chipping hammers, rock drills, concrete breakers and needle scalers.
However, since none of the published standards specified the design of the loading device in detail, there
were inevitably many small differences between the loading devices which were manufactured. The question
then arose as to whether these differences affected the measured results of the tests, for which the loading
devices were used.
In preparation for producing this document, a PNEUROP working group performed a series of tests to
investigate the effects, on the results of vibration tests on concrete breakers, of varying the detailed design of
the loading device. The tests, which used different sizes of concrete breakers (non of which incorporated
vibration damping features), were conducted using the largest size of loading device (60 mm internal
diameter). ISO 8662-5: 1992 and EN 28662-5:1994/A1 were the reference standards applied. The test series
was designed to investigate whether varying the designs of the tool piece and anvil affected the results.
Particular attention was, however, also paid to evaluating the effects of varying the clearances between
moving parts and to checking measurement repeatability throughout the working day and from one day to
another.
The investigation by the PNEUROP working group indicated that the loading devices presented in this
document are of a rugged design, permitting good repeatability of measurements, and that their performance
is insensitive to small dimensional changes or usage rate. Repeatability throughout the working day and from
one day to the next was found to be very good. The repeatability of measurements obtained for each
individual operator was also found to be good, with the result that mean results from three operators gave
good repeatability, despite significant variations between individual operators. For non-vibration damped
breakers, the choice of tool piece and anvil (either Type 1, 2 or 3 in this document) did not have a significant
effect upon the vibration, when measured according to the standards used.
In this guidance document, the PNEUROP Tools Committee offers a family of designs for dynamic loading
devices, for reference by committees charged with developing standards for the measurement of noise,
vibration or performance of percussive power tools. When selecting and, if necessary, adapting a loading
device for a specific standard, it is expected that the responsible committee will perform tests to verify its
suitability for their purpose. The PNEUROP Tools Committee would be grateful to receive any information
resulting from such tests, in order that this guidance document may be revised and improved as more
knowledge is acquired.
0
Introduction
The measurement of physical parameters such as noise and vibration from hand-held tools has been the
subject of investigation for many years. The means by which these parameters can be obtained have resulted
in a number of devices to provide for a "working load" for the tool being investigated.
The resulting data can provide the customer with relevant information by the use of a well-defined method
that is both repeatable and reproducible. The last two issues, repeatability and reproducibility, are vital where
the data obtained is required to demonstrate compliance with legislative requirements.
The equipment used to provide a "load" against which the hand-held power tool can "work" should be easily
constructed from common materials and provide for ease of maintenance. This publication is intended to
provide the specifications and guidance for such a loading device.
2
1
Scope
To provide a specification on design and construction and guidance on use and maintenance of a dynamic
loading device for the following categories of hand-held power tools;
¾
percussive;
¾
rotary-percussive.
The device may be used when measurements are being made for either vibration, noise or performance,
including when required for specification in test standards.
2
General
The dynamic loading device is given the common name of DYNALOAD. The device consists of a metallic
cylinder filled with steel balls on which the hand-held power tool is brought to bear and which absorbs the
energy transmitted by the tool. The device can either be fixed to a surface or buried below the working floor
level.
Tool piece
The diagram in Figure 1 identifies the essential items
making up a Dynaload. The specification of each item is
identified later in this publication.
The Dynaload device absorbs the blow energy from the
power tool. Much of the shock wave is absorbed by the steel
balls, however some 15% to 20% is reflected back to the
power tool, as would be the case in a normal working
situation.
Free
length
‘h’
Guide bush
Anvil
Cylinder
Steel balls
Steel plate
Figure 1 - Basic elements
Hole in
ground
Free
length
‘h’
Sound
absorbing
material
(e.g. sand)
Gap filling
material
Screening slab
(Top surface level
with ground)
Hole in
ground
Sound
absorbing
material
(e.g. sand)
The diagram in Figure 2 shows a typical
construction of an assembly, which holds
a Dynaload below ground. This would be
utilised with concrete breakers, as it
would afford a convenient location for
the operator during testing conditions.
Figure 2 - Below ground mounting
3
3
Relationship with standards
This standard only specifies the Dynaload device and it is the responsibility of experts on international and
other standards committees and users of this specification to:
¾
select the appropriate size and type of Dynaload test rig for the particular tool being tested, such as
noise, vibration or performance testing
¾
specify any additional requirements needed for the purpose of the test, such as mounting blocks,
screening slabs, etc.
¾
specify the loading and operating conditions for the tool under test.
When selecting or referring to a particular type of Dynaload test rig, the following format shall be used:
Size / Type, e.g. “60 mm / Type 1 Dynaload”,
where “Size” refers to the internal diameter of the cylinder (see 4.1) and “Type” refers to the design of test
tool and anvil (see 4.2)
4
Design
4.1
Preferred sizes
The Dynaload should be constructed to be of an appropriate size depending on the hand-held power tools to
be tested. Three preferred sizes are in use, i.e. cylinder diameters of 20mm, 40mm and 60mm, these sizes
relate to the requirement for absorbed power capabilities.
4.2
Anvil and Test tool
4.2.1
Type 1:
1 piece - solid formed tool piece and anvil
Split guide bush
Cylinder
Tool and
anvil as
unitary
assembly
(See Annex A)
The diagram in Figure 3 identifies the form of a one-part tool/anvil. This
may be considered to be superior to the two-part construction where the
measurement of noise is concerned. A unitary construction reduces the
possible sources of unwanted noise.
This type of construction is more costly than a two-part assembly. A twopart assembly can utilise the actual tool steel used by the hand tool.
Where the tool steel is used it must be of circular cross section and
dimensioned to pass through the
bush.
Split guide bush
Figure 3 - One-part tool
The diagram in Figure 3a shows a spring, which is utilised when the
effects of recoil from certain types of percussive power tool being
tested may have an adverse effect on the Dynaload assembly and
consequently any readings being taken. The spring is an optional item
and should be used only when required.
Recoil
spring
As in
Figure 3
Figure
4
3a
-
Recoil
spring
4.2.2
Type 2:
Tool piece with
taper fit end
2 piece - tapered end tool piece with a mating anvil
(See Annex B)
Guide bush
The diagram in Figure 4 identifies an alternative approach to the
construction of the tool piece and the anvil. Although in separate parts
in-use they act as a one-part tool.
This construction allows for a simple design for the guide bush as a
one-part construction rather than that identified in Figure 3.
Anvil with
taper fit hole
A standard tool steel can be modified to provide the necessary taper fit.
Where the tool steel is used it must be of circular cross section and
dimensioned to pass through the bush.
Cylinde
Figure 4 - Taper fit tool piece
4.2.3
Type 3:
2 piece - ball-ended tool-piece with a mating anvil
(See Annex C)
Tool piece
The diagram in Figure 5 identifies the construction of the tool and anvil
as separate parts.
Guide bush
This type of construction lends itself to the testing of rotating tools.
The mating joint between the anvil and tool should be a close fit, as
should the tool and guide bush.
A standard tool piece can be utilised with a modified end to fit the anvil.
Where the tool steel is used it must be of circular cross section in the
vicinity of the guide bush and dimensioned to pass through it.
Anvil
Cylinder
4.2.4
Type 4 Needle scaler type
Figure 5 - Two part test tool
(See Annex D)
Needle scaler
Needles
Modified
anvil
Figure
6
-
Needle
The diagram in Figure 6 shows the arrangement to be adopted when
using the Dynaload with needle scalers. The guide bush is removed
and the clamp plate is retained through which the needles of the needle
scaler pass and then rest directly on to a modified anvil having a small
recess to secure the needles and avoid contact with the cylinder wall.
scaler
5
5
Performance/Power measurements
When the Dynaload is used for performance or power
measurements then provision for cooling as well as the
measurement of temperature should be included.
The diagram in Figure 7 identifies the basic requirements for the
measurement of power or performance. Where the Dynaload is to
be used for extended periods of time then cooling is required. This
may be water, oil or air depending on conditions of the test and
whether the coolant is to be used as the source of heat for
calculation purposes.
Thermocouple
mounting point
Coolant
inlet
Figure 7 - Power measurement
6
Operational features
Before operating the Dynaload device the Dynaload should be checked that all parts are within the
dimensional specifications set out in this document.
If the condition of the steel balls has deteriorated then the entire charge should be replaced. The steel balls
will during use be compressed and become fragmented therefore the decision to replace the charge of steel
balls will depend very much on experience. As a guide to the decision making process when the surface
layers have become fragmented then this can be taken as the time for the change. It is false economy to
salvage balls from an exhausted batch since they are an unknown quantity and may lead to premature
deterioration of steels balls in a new batch.
The Dynaload is specified in three sizes according to the power and size of the hand tool. The specified
lengths of the tool piece should not be exceeded since this will lead to undue flexing of the tool piece and
breakage, and may affect the noise and vibration readings.
Before any measurements are undertaken when a new charge of steel balls is introduced the equipment
should be run for a period of 15 to 30 minutes to allow the column of steel balls to settle. In the new
condition the point contact on each surface leads to a rapid deterioration of the surface of the balls that is
quickly nullified by the running in procedure.
7
Maintenance
The Dynaload being of simple construction requires little maintenance. Since the device is constructed from
steel the main problem will be rusting, especially where it is used with water as a coolant or air that has not
been dried. Also where the device is used outside and underground regular inspection of the steel balls and
the main tube is essential.
When stored for long periods the steel balls should be removed and packed separately. The main
construction should be stored in a dry area or be coated with a layer of grease or oil. The internal surface of
the Dynaload should be inspected for wear. The Dynaload has been found to have a long service life with
little deterioration of the main cylinder. However it has been found that for approximately 40mm from the
top surface of the steel balls the cylinder wall becomes grooved. This is the area, which absorbs the majority
of the blow energy.
6
8
Construction
All Dynaload variations may have the items identified in the table below. Their actual construction will
depend on the type chosen for a particular application or preference on the part of the user. The construction
of the Dynaload does not require any special engineering practices and can be successfully produced by any
general engineering facility.
Table 1 – Identity of component parts as shown on diagrams in Annex A, B, C and D
Diagram
Ref. number
Quantity
Description
1.
2.
3.
4.
4a
4b
4c
5.
6.
7.
8.
9.
1
1
4
1
1
1
1
1
1
1
1
1
Bottom plate
Cylinder
Stud
Type 1 anvil
Type 2 anvil
Type 3 anvil
Type 4 anvil
Bush Clamp plate for item 7
Flange
Guide Bush
Steel ball reaction plate
O-ring
10.
11.
12.
13.
1
4
4
As required
O-ring
Nut
Screw
Steel balls
14.
15.
15a
15b
15c
1
1
1
1
1
O-ring
Type 1 toolpiece
Type 2 toolpiece
Type 3 toolpiece
Type 4 toolpiece
Note
Identified in Annex A
Identified in Annex B
Identified in Annex C
Identified in Annex D
Cylinder seal this is optional and only required if a coolant
is to be used during testing
Sited in a groove in the o.d. of item 7
For item 3 of size M16 to secure item 6
M10 bolt to secure item 5
For endurance tests it may be more practical to use large
diameter steel balls, e.g. 6mm.
Sited in a groove in the i.d. of item 7
Identified in Annex A
Identified in Annex B
Identified in Annex C
Identified in Annex D
Note 1: Tolerances
The components in Table 1 are shown graphically in various Annexes, where
required or known tolerances are given which are in accordance with ISO 286-2. Where no tolerance
is shown but would be desirable then the method for allocating such a tolerance should be done in
accordance with ISO 1829 and ISO 2768-1.
Note 2: Materials
Material specifications given in this publication are those which have been
successfully used, however they are not exclusive and alternatives may be employed provided that
the material is able to fulfil the functional requirements.
7
Annex A
Type 1 - Single piece square-end Dynaload
8
Annex B
Type 2 - Single piece taper-fit Dynaload
9
Annex C
Type 3 - Cup/Ball-end Dynaload
10
Annex D
Type 4 - Needle scaler variant Dynaload
.
11
Annex E
Design and Constructional Details
Note: The Item numbers in this Annex follow the numbering system in Table 1 and Annexes A, B, C and D.
1a
Bottom plate
1b
Bottom plate regulated coolant supply
Where a regulated coolant supply may be required
then the following dimensional details are identified
as a practical alternative to that shown for a plain
connection at the bottom of this page.
Dynaload Size
Dimension
20
40
60
A
50 0+ 0.039
70 0+ 0.046
90 0+ 0.054
B
35 0+ 0.160
55 0+ 0,190
75 0+ 0,190
C
D
O-ring
27
47
67
6
10
10
Diagram ref. 9 fits in groove formed
by dimensions ‘B’ and ‘C’
Mild steel
AISI 1020
SS 2172
Not required
Material
Hardening
All dimensions are as given on the diagram.
Table 2 – Bottom plate specifications
12
Annex E continued
2. Cylinder
Dynaload Size
Notes
Dimension
20
40
60
A
50 −−00..060
134
70 −−00..060
134
90 −−00..060
134
B
20 0+0.052
40 0+0.62
60 0+0.074
C
D
165
G¼
200
G½
250
G½ or
G⅜
This dimension may be as shown on the diagram or it may represent
the outside dimension of the whole tube length. The only proviso is
that it should fit the allocation in the bottom plate
This dimension is given where a coolant outlet is to be provided, this
is an optional item and only required where the Dynaload is used for
extended operation such as for power measurement characteristics.
These port sizes are not critical any convenient fitting may be used.
Additional Specifications
Material
Hardening depth
Surface hardness
AISI 8620
SS 2172
BS970 805M20
DC 1 ± 0,1
RC 62 ± 2
Hardness relates to the finished part
Table 3 – Cylinder specifications
13
Annex E continued
3. Stud
Dimension
Dynaload Size
20
40
L
210
Additional specification
Material
Nut
270
60
330
AISI 4340
SS 2225-05
BS970 817M40
Diagram ref. 11
Table 4 – Stud specifications
14
Annex E continued
4. Anvils
4c - Type 4 anvil
4a – Type 2 Anvil
Dynaload Size
Dimensions
20
40
60
30
45
A
Deleted for
this size
D
19,60− 0,1
39,60− 0,1
59,6 0− 0,1
R
50+0,5
90+0,5
150+0,5
RS
L
1
25
2
35
2
35
Additional specifications
4b – Type 3 Anvil
Material
Surface hardness Rc
SS 2090
Type 2: 59 ±1
Type 3 & 4: 55 ± 2
Hardening depth
+0,3
All types: 0,5 0
M6 tapped holes
To assist in the removal of anvil
Table 5 – Anvil specifications
15
Annex E continued
5. Bush clamp plate
Dimension
D
Additional specifications
20
Dynaload Size
40
60
30
30
50
Mild steel
AISI 1020
SS 2172
Material
Table 6 – Bush clamp plate specifications
16
Annex E continued
6. Flange
Dimensions
A
B
C
20
Dynaload Size
40
60
40,5
20,5
50,5
40,5
70,5
60,5
50 0+0.039
70 0+0.074
90 0+0.087
Additional Specifications
Material
Mild steel
AISI 1020
SS 2172
Table 7 – Flange specifications
17
Annex E continued
7. Guide Bush
Dimensions
A
20
10
B
Dynaload Size
40
+0 , 036
0
16,4
0
−0 ,110
18
60
+0 , 043
0
35,2
30 0+0, 052
0
−0 ,160
55,2
0
−0 ,190
C
20 −−00,,040
073
40 −−00,,050
089
60 −−00.,060
106
D
13,7 0+0,110
21,7 0+0,130
34,800,160
E
F
60
40
60
50
60
70
Material
type
Clearance
O-ring
O-ring
Bronze: ASTM B139 Alloy 524000
The
diagram
shows
the
dimensioning for the application of
the bush as either in solid form or
as a split bush. The splitting
process is achieved by applying a
cut of dimension as shown in the
diagram on the right. The width of
the cut applies to all sizes of
dynaload
A clearance of 1mm on the diameter of the hole should be maintained
between the bush and the inserted tool piece.
Diagram ref. 10 fits in groove on outside diameter at the base of the
bush
Diagram ref. 14 fits in groove on inside diameter at the top of the bush
Table 8 – Guide bush specifications
18
Annex E continued
8. Steel ball reaction plate
Dimensions
D
R
20
19
0
−0 ,130
2
Dynaload Size
40
39
0
−0 ,160
4
60
59
0
−0 ,190
4
Material
Surface hardness Rc
Hardness depth mm
SS 2090
55 ± 2
0,50+0,3
Table 9 – Steel ball reaction plate specifications
9. O-ring
See Item 1 and table for specifications. The O-ring material requires no specific characteristics so any
standard type may be used.
10. O-ring
11. Nut
Specification as in Table 1
12. Screw
These screws to fix the bush clamp plate have no particular specification. General engineering quality screws
may be used.
19
Annex E continued
13. Steel balls
Dimensions
20
Metric (mm)
Imperial (inch)
3.15
18
Steel ball column height
inside cylinder (mm)
50 ± 5
Dynaload Size
40
60
4 or 3.96
5 32 (equiv 3.96 mm)
100 ± 5
150 ± 5
Material
Surface hardness Rc
Steel
> 63
Table 10 – Steel ball specifications
14. O-ring
20
15. Type 1 toolpiece
Dimensions
20
TL
L
D
Dynaload Size
40
60
Includes “L” & Manufacturer dimensions
See Note L
19,5 0− 0,1
39,57 0−0,1
59,64 0−0,1
A
12 0+0,1
24 0+0,1
38 0+0,1
d
14 0−0,1
24 0−0,1
30 0−0,1
R
4
5
6
Power tool type
Material
Surface hardness Rc
NOTE L
This dimension incorporates a length which is supported within the dynaload and a “free” length
between the “upper surface” of the dynaload and the base of the power tool where the inserted tool is
held by a retainer. The “upper surface” of the dynaload may be considered as either the dynaload
surface itself (See Figure 1) or any acoustic cover placed over the dynaload (See Figure 2). The
dimensions given in this table are advisory but have been shown to give good results.
Steel
50/55
Riveting hammer
Other percussive tools
Table 11 – Type 1 toolpiece specifications
Dynaload Publication/Version
21
1.2 – Oct 2005
Dynaload
20
40
20
40
60
Free length
10 ± 4
40 ± 15
60 ± 20
80 ± 20
15a
Type 2 toolpiece
Dimensions
20
TL
L
Dynaload Size
40
NOTE L
Power tool type
Material
Surface hardness Rc
60
See Note L
Steel
50/55
Riveting hammer
22
1.2 – Oct 2005
Dynaload
20
40
20
40
60
Free length
10 ± 4
40 ± 15
60 ± 20
80 ± 20
15b
Type 3 toolpiece
Dimensions
20
TL
L
d
R
RT
RZ
Dynaload Size
40
NOTE L
Power tool type
Material
Surface hardness Rc
60
See Note L
30
15
5±1
2
Steel
50/55
Riveting hammer
23
1.2 – Oct 2005
Dynaload
20
40
20
40
60
Free length
10 ± 4
40 ± 15
60 ± 20
80 ± 20
Annex F
Recoil spring
1) The end shall rest on the subsequent coil
2) Delete if not required
Dimensions
20
As given on diagram
Dynaload Size
40
60
Spring
Material
Shear modulus
Total number of coils
Direction of winding
Length at minimum force
Minimum force
Shear stress at minimum force
Rate
SS 1774-04
78500 N/mm2
4,5
Right
25 mm
438 N
150 N/mm2
215 N/mm
Table 14 – Recoil spring specifications
24
Bibliography
a) Standards that currently make reference to or use the dynaload
ISO 8662
Hand-held portable tools – Measurement of vibrations at the handle;
Part 2: Chipping hammers and riveting hammers
(also as EN 28662-2)
Part 3: Rock drills and rotary hammers
Part 5: Pavement breakers and hammers for construction work
(also as EN 28662-5)
Part 14: Stone working tools and needle scalers
(also as EN 28662-14)
ISO 15744
Hand-held non-electric power tools – noise measurement code
– Engineering method (Grade 2)
(also EN 15744)
b) Standards referred to or are of use in the application of this publication
ISO 286-2
ISO system of limits and fits – Tables of standard tolerance
grades and limit deviations for holes and shafts
ISO 2768-1
General tolerances for dimensions without tolerance
indications – Tolerances for linear and angular dimensions
c) Material standards referenced in this publication
AISI 1020
is one of the very commonly used plain carbon steels. It has a nominal carbon content of
(SAE J1397) 0.20% with approximately 0.50% manganese. It is a good combination of strength and
ductility and may be hardened or carburized.
AISI 4340
is a heat treatable, low alloy steel containing nickel, chromium and molybdenum. It is
known for its toughness and capability of developing high strength in the heat treated
condition while retaining good fatigue strength.
AISI 8620
is a hardenable chromium, molybdenum, nickel low alloy steel often used for carburizing to
develop a casehardened part. This casehardening will result in good wear characteristics.
ASTM B139
Bronze Alloy 524000
SS 1774-04
SS 2090
SS 2172
SS 2225-05
BS 970
Replaced by Parts 1 to 5 of BS EN 10277 and BS EN 10278:1999. Therefore the materials
805M20 and 817M40
NOTE:
AISI – American Iron and Steel Institute
SAE – Society of Automobile Engineers (US)
SS – Swedish Steel
25

DYNALOAD - design, construction, use and maintenance

Transcription

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