Manufacture of Large Seamless Steel Tubes by the Tschulenk Forge

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M anufacture of Large Seamless Steel Tubes
by the Tschulenk Forge-Rolling Process
By ARTHUR J. HERSCHMANN,1 a n d LEOPOLD TSCHULENK2
In view of the large size of the hollow blocks to be worked by
the Tschulenk process, the revolving Pilger rolls were not in­
cluded. Such rolls revolve very slowly and would therefore
have to transmit excessive torsion. The motor to drive such
a mill would necessarily be very large and expensive, and the
drive would be exceedingly complicated.
The Tschulenk mill3 is illustrated in Figs. 1, 2, and 3; Fig. 1
showing an elevation in longitudinal section with the mill in
position for the start of the rolling operation, Fig. 2 the corre­
sponding plan view when the work piece [thick-walled hollow
block (1) ] has been inserted, and Fig. 3 various sections through
the mill. In Fig. 3, A shows one-half the Tschulenk mill, at
section c-d in Figs. 1 and 2; B shows one-half the mill at section
e-f; C shows the section at g-h through the carriage (14) and
ARGE seamless steel tubes and other thick-walled hollow the hollow block; D, section i-k: E, section l-m; and F, shows
steel bodies of diameters in excess of 20 in. are in wide and section n-o.
varied use today and the field of their application is growing.
The Tschulenk mill carries three or four oscillating Pilger
These products are used extensively for high-pressure boilers and
rolls (2) which are arranged within one vertical plane of the roll
containers, vessels in the chemical industry, reaction chambers, stand (9). These rolls have leverlike extensions (3) upon which
etc., for the cracking and the hydrating of coal, tar, oil, and a the hydraulic work plungers (5) press by means of short thrust
special field of use is presented by torpedo tubes for warships.
rods (4), thereby effecting the movement of the rolls. To with­
The aim of the Tschulenk forge-rolling process is the pro­ draw the work plungers (5) together with the rolls (2) which are
duction in the simplest possible way, through a direct fiber- attached to them, return plungers (6) are provided, the latter
stretching process, of such seamless tubes and other hollow steel being connected with the main plungers (5) through the yokes
bodies of large diameter and great length in wall thicknesses up (7) and pull rods (8).
to the thickest demanded at present, with a free choice of the
The hydraulic cylinders (10) and (11), within which plungers
steel analysis. The fundamentals underlying the proposed proc­ (5) operate, as well as the cylinders for the reverse plungers (6)
ess and the details of design of the mill itself are based on sound are attached to the roll stand (9). To protect that roll stand
engineering principles and a broad knowledge of art of steel (9) from bending stresses caused by the process of rolling, ten­
manufacture. A mill of this type, however, has not as yet been sion rods (12) are provided and arranged crosswise.
built.
The rolls (2) are linked to the carriage (14). At the beginning
D e s ig n o f t h e T s c h u l e n k M il l
of the operation the hollow work piece (1) is placed upon the
carriage (14) so that it goes to and fro together with that car­
As the present state of tube-rolling technique makes it possible, riage
when the rolls (2) move during the rolling process.
through the Pilger method, to produce tubes of large diameter
Pilger rolls have heretofore always required a mandrel of
and length up to certain limits, the Tschulenk process has re­ greater
length than that of the hollow block through which it
tained the Pilger tube-rolling principle.
passes. In contrast to this the Tschulenk forge-rolling mill re­
1 Agent in United States for Vitkovice Steel Works, Czechoslovakia, quires but a very short plug (15), inside of the hollow block, of a
and representing the Loeffler Boiler System; offices in New York, length only slightly greater than that of the developed contour
N. Y. Mem. A.S.M.E. and I.M.E. Mr. Herschmann was formerly
mechanical engineer of various corporations and has engaged in the of the work rolls (2).
Hydraulic pumps at a pressure of 3000 to 3750 lb per sq in.
design and operation of several large plants.
2 Moravska Ostrava, Czechoslovakia. Mr. Tschulenk received will be required for operation of the mill. To keep the pump
his technical education and practical training in Vienna, Austria. capacity required at a minimum these pumps should operate con­
He was employed in various capacities in connection with the building
of such plants in Europe as at Rombas in Alsace Lorraine and the tinuously during the process of rolling and supply the pressure
plants of the Alpine Montan Gesellschaft in Styria. He designed water to air-cushioned accumulators for the peak-load periods.
In th is paper th e authors present a new technique for
the m anufacture o f seam less steel tubes and other hollow
steel bodies w ith diam eters from 20 to 60 in . or even
greater, lengths up to 60 ft., and wall thicknesses from
approxim ately 6/ a in. up to alm ost any thickness th at
m ay be required. Except in very special instances such
tubes or vessels would be com pleted from th e original
hollow steel block in a single pass w ithou t previous forging
of the ingot and w ithout the necessity o f subsequent tool­
ing. B oth th e design of th e m ill and th e details of its
operations are described, and in conclusion th e authors
deal briefly w ith th e m anufacturing econom ies which
m ay reasonably be expected.
L
the plants for the Reschitzer Works in Roumania and for the Jurjewsky-Sawod Works in Russia. Mr. Tschulenk’s last employment
extended over a period of 23 years with the Vitkovice Steel Works,
as designer-in-chief of their tube plants. During that time he also
designed tube plants for Germany and Russia.
Contributed by the Iron and Steel Division for presentation at the
Annual Meeting, New York, N. Y., December 3 to 7, 1934, of T h e
A m e r ic a n S o c ie t y o f M e c h a n i c a l E n g i n e e e s .
Discussion of this paper should be addressed to the Secretary,
A.S.M.E., 29 West 39th Street, New York, N. Y., and will be accepted
until January 10, 1935, for publication in a later issue of Transac­
tions.
Note: Statements and opinions advanced in papers are to be un­
derstood as individual expressions of their authors, and not those of
the Society.
O p e r a t io n
The working operation of the Tschulenk forge-rolling mill is as
follows:
The hollow work block (1) is placed on the carriage (14) be­
tween the roll stand (9), the withdrawing plug (15) and support­
ing box (30) as shown in Fig. 2. The inside diameter of the
hollow block (1) is made larger, to start with, than the inside
diameter of the finished tube and also a little larger than the
outside diameter of the plug (15), as is generally the rule with
3 The Tschulenk process is covered by United States Patent No.
1,928,741.
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TRANSACTIONS OF THE AMERICAN SOCIETY OF MECHANICAL ENGINEERS
IRON AND STEEL
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F i o . 3 V a r i o u s S e c t io n s T h r o u g h M i l l
(F o r lo c a tio n s of seo tio n s, see F ig s. 1 a n d 2.)
Pilger rolling mills. The plug (15) is mounted on the mandrel
rod (16) so that it can be changed readily when necessary. The
mandrel (16) has a central bore for water cooling, to prevent
excessive heating due to radiation from the hot hollow block (1).
The mandrel rod (16), together with its plug (15), is pushed
through the hollow block (1) between the work rolls (2), whereby
the mill is brought into its rolling position as shown in Fig. 1.
The forward pushing and the back pulling actions of the mandrel
rod (16) are accomplished by the double-acting hydraulic cylin­
der (17) as shown in Figs. 1 and 2.
By lowering the locking gate (18) into the annular groove of
the mandrel rod (16), the latter is made rigid with the carriage
(14) in a longitudinal direction. The plug (15), together with
the hollow work block, will now participate in the same to and
fro movement of the forging rolls (2).
Following each work stroke—and subsequent return stroke—of the mill, the hollow block (1), after complete release from the
rolls (2), is pushed forward by the plug (15) for a certain amount
of feed and at the same time turned for a predetermined degree
of circumferential feed.
The mechanism to accomplish the turning and forward feed
of the hollow block (1) is provided back of the supporting box (30)
and a description of this obvious device may be found in the
patent.8
This working process is repeated until the hollow block (1) is
completely rolled out, when the finished tube is completely
pushed off the rolling plug (15).
Thereupon the locking gate (18) is withdrawn radially by motor
(19) and the mandrel rod (16) together with plug (15) is with­
drawn by the hydraulic cylinder (17) into the position shown in
Fig. 2, preparatory to another rolling operation, when a new
hollow block is placed on the carriage (14).
To reset the mill from the production of one tube size to an­
other within its work range, it is only necessary to change the
pass cheeks (2) on the oscillating rolls (3), Fig. 1, as well as the
mandrel plug (15). The mill has no moving parts located inside
the hot hollow block, where their functioning could be impaired
by the radiated heat, with the exception of the short plug
(15) which, if desired, could be water-cooled. It should be
noted that this short plug (15) in its reciprocating movement
does not come in contact with the hollow block (1) for its full
length so that excessive cooling of the block to be rolled, as well
as excessive heating of the plug are avoided.
C o n c l u s io n
The Tschulenk mill is primarily suited for economical pro­
duction of finished seamless steel tubes and other hollow bodies
of diameters ranging from 20 to 60 in. with lengths up to 60 ft.
It is also considered entirely possible to go greatly below these
limits and also beyond them, by special design. The demand
for hollow bodies in excess of the stated dimensions, however,
is small at the present time. To cover the 20- to 60-in. range
of diameter two sizes of the Tschulenk forge-rolling mills are pro­
posed; one for diameters from 20 to 40 in. and a larger size for
the balance of the range from 40 to 60 in.
Tubes of the stated diameters with wall thickness in excess
of about 5/ 8 in. can be produced in a single pass through the mill
and the time required to complete a finished high-pressure tube
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TRANSACTIONS OF THE AMERICAN SOCIETY OF MECHANICAL ENGINEERS
of 50-in. diameter, 2-in. wall thickness, and 50-ft length would
not be over 22 minutes. During that time the hollow block will
remain sufficiently hot to insure efficient rolling of the block end.
With ample cropping of the bad ingot ends, the cast hollow
steel block will in most cases suffice as raw material for the
Tschulenk mill and the product thus produced should require
no final tooling except where it is an “a priori” necessity as in
the case of torpedo tubes.
The scrap resulting from the operation of the Tschulenk sys­
tem will be only from 20 to 25 per cent of the original block as
compared with a waste of as much as 2/ s of the original steel in
the case of hollow forging under a press.