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Патент USA US2108790

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Feb. 22, 19385.
kS. D. INSCHO
_ 2,108,790
TUBE DRAWING APPARATUS
Filed May 9, 1934
IN VEN TGR.
2,108,790
"Patented Feb. 22, ‘193sv
j UNITED STATES PATENT OFFICE
TUBE DBIAÍSÉVSÄÍÍPPARATUS '
Sidney 5D. Inscho, Shelby, Ohio
10 Claims.
This invention relates to themanufacture of
tubular blanks and particularly to the reduction
and elongation of tubular blanks, particularly
seamless tubing, by so-called cold drawing op
5
erations.
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,
An -object of the present invention is to pro
vide an improved method and apparatus for re
ducing and elongating ltubular blanks‘vby cold
'drawing operations and whereby the -frictional
10 resistance yor surface drag set up as the blank
is drawn through the die is materially lessened,
4 thus providing a more efñcient drawing opera
tion, improving the characteristics of the final
product, and increasing the life ofthe appa
ratus.
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A further object ofthe invention is to provide
an apparatus having means adapted to grip the
forward end of the blank for drawing the latter
through a reducing die and also having a yield
20 ingly> mounted-resistance means adapted to grip
the rear end of the blank so as to resist or op
pose the forward travel of the blank, the latter
means thus exerting a resistanceforce, tending
to stretch the fibers of the metal at the locality
25 of the die and to~relieve the frictional or surface
drag on the blank at that point. rAs a conse
quence less power is required to draw the blank
through the die to effect elongation thereof and
reduction of the wall thickness. Moreover, by
30 --relieving or lessening the-frictional resistance
to the passage of the blank through the die,- im-
proved inner and outer surface characteristics of
the blank are secured.
,
It is a well recognized fact that a cold draw
35 ing operation requires _considerable power for
pulling the tubular blank through the die to ef
fect reduction vthereof to the diameter of the
internal mandrel. Ordinarily, before ‘each draw
ing operation, the blank is carefully annealed so
40 that the _metal will not be subjected to undue
strain or be fractured during the drawing opera
tion. The tubular blank must be well lubricated
to avoid injury not only to the inner and outer
surfaces of the tube but also to the die and man
45 drei. Even though the die and mandrel are
< made of high grade material, carefully prepared
and accurately finished, they are subject to rapid
wear and hence the maintenance thereof becomes
a costly item. Even greater diñiculties are en
50 countered in the reduction of stainless steel tubes,
particularly those of certain analyses, this tub
ing being very difficult to cold draw due to the
physical characteristics thereof. In cold draw
(o1. zus-"1)
,
in ñnding a lubricant that will give its surface
sufficient smoothness to offset the resistance set
up by the die and mandrel during the cold draw~
ing operation.
'I‘he present invention to a material extent
overcomes the foregoing difñcultiessince in ae'
cordance therewith considerable of the surface
drag and resistance' set up at the locality of the
die is eliminated.
.
»
Other objects of this invention will appear in 10
the following description and appended claims,
reference being had tothe accompanying draw
ing forming a part of this specification wherein
like reference characters designate corresponding
parts in the several views.
~
Fig. 1 is a .plan View, partly in sectiomci an
apparatus for carrying out the present invention.
Fig. 2 is a side elevation of the construction
showninFig.
1.
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Fig., 3 is a fragmentary enlarged side elevation, 20
partly in section. of the apparatus.
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Fig. 4 is an enlarged sectional view illustrating
the die and the manner in. which the tube is re
duced.
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'
Before explaining in detail the present inven
tion it is to be understood that the invention is '
not limited in its application to the 'details of`
construction and arrangement of parts illus
‘trated in the accompanying drawing, since the
invention is capable of other embodiments and of 30y
, being practiced or carried out in various 'ways
Also it is to be understood that the phraseology ’
or, terminology employed lherein is for the pur
pose of description and not of limitation, and it
is not intended to limit the invention claimed
herein beyond the requirements of the prior art.
In the drawing there is illustrated, by way of ‘
example, an apparatus for carrying out the pres
ent method, this apparatus comprising a draw
bench I0 upon which is mounted a gripping>
device or pulling head II forgripping one end
of the tubular blank B.
One en_d of a rack I2
is suitablyconnected tothe gripping device Il
and the latter is provided with suitable guide rolls
I3 for guiding the same longitudinally in a pre
45
determined path on the bench I0. The forward
end of the benchfhas an' upstandlng abutment I4
forming a stop for limiting the forward travel of
the pulling head1 I. The rack I2 isadapted to
engagea rack"'gear I5 fixed upon a shaft I6
suitably mountedfor rotation in a machine vI‘I
of the pinch roll type. 'I'he forward end of l¿the
rack I2 carries a guide roll I 8 mounted to travel
ing stainless steel tubes it has been found that upon a suitable support I9. Power is suppliedvtrr`
increased difficulties arise owing to the difficulty ` .move the rack I2 longitudinally by means Vof a"
‘ 2
2,108,790
, variable speed motor 20 .through a gear reduc
tion unit 2| having a gear 22 meshing with a
gear 23 fixed upon the end of the cross-shaft
|6. A suitable control device 24 may be asso
ciated with the motor 2li to control the electrical
energy supplied thereto.
‘
A suitable support 3G is spaced from one end
of the draw bench i0 and in alinement there
with. Movably mounted upon this support by
cuide rollers, as illustrated, is a second gripping
device or pulling head 3| which is adapted to
by exerting a rearward pulling or resistance force
on the blank at the rear side of the die and in
opposition to the forward pulling force exerted by
the head Ii, the ñbers of the metal at the reduc
tion point C may be placed under sunlcient ten-v
sion to effect a stretching of the tubing, and this
stretching force is consolidated at this weakest
point in the blank. Thus, the moving resistance
force due to the head 3| is consolidated at the
weakest point in the blank, i. e. at the point of re 10
duction in wall thickness at the mouth of the
grip the rear end of the tubular blank B while
die, and the result of this rearwardly directed
permitting ‘free longitudinal movement therein of ~ longitudinal force is to effect a definite stretching
a mandrel 33 carried by the gripping device or
of the ñbers of the metal at this locality. 'I'he
l5 pulling head il. The pulling head 3| is con
head 3|, of course. travels forwardly as the tube
nected by pull rods 34, which straddle the mandrel is pulled through the die, but the resistance set
33, to a yoke 35 fixed upon one end of a piston up by the piston 38 is adjusted so as to exert the
rod 36 slidably mounted in the hydraulic cylinder
3l. A piston 38 is secured to the inner end of
20 the piston rod 3_6 and is adapted to reciprocate
within the bore of the cylinder against a body
of oil or other suitable fluid medium. The hy
draulic cylinder 31 is provided with a by-pass
pipe 40 communicating with the interior of the
25 cylinder at opposite ends of the piston, and in
the length of this pipe there is located a suitable
control valve 4| by which the flow of oil from
one side of the piston to the other may be con
trolled so as to Vary the resistance of the piston
30 to the longitudinal travel of pulling head 3|.
Mounted on the rear end of the draw bench
l0 and fastened thereto is a die head 42 which
has a control opening 43 counterbored to receive
a circular die 4t centrally apertured for the pas
35 sage therethrough of the tube B and mandrel 33.
« The central annular opening in the die 44 is of
materially less diameter than the initial diam
eter of the tubing B before reduction and elonga
tion thereof, the die as shown having a constricted
40 opening which is of flared or tapered formation
»as illustrated, for example, in Flg. 4.
Preparatory to the operation of the machine,
‘ the tubuiar blank B 1s pointed at its forward end
and inserted through the constricted opening in
45 the die 44 and is clampedin the Jaws of the
pulling head or gripping device II which at that
time is initially positioned adjacent the die head
42. 'I‘he opposite end of the blank B is gripped
by the clamping ,laws of the gripping device or
50 pulling head 3|. It is understood that the man
drel 33 is positioned within the blank and with
the latter is gripped at the same time at its for
ward end by the head ||. Power is supplied to
cause the pulling head || and the blank B to
55 gether with the mandrel 33 to move in the direc
tion indicated by the arrows in Fig. 3. This move
ment is resisted but not prevented by the rear
'pulling head 3| through the action of the piston
33 in the cylinder 31. As a consequence the blank
is subjected to tension or stretching action and
the gripping device 3| is caused to move in the '
direction of the arrows in Fig. 3 but at a slower
' rate than the gripping device Il. ‘
Ordinarily in the Ycold drawing operation» the
greatest surface drag and resistance to the pas
sage of the tubing through the die -is at the
locality of reduction, indicated at C in Flg. 4,
where the tubing has an abrupt shoulder. At this
point there is exerted in the direction of the arrow
70 D an opposing force which renders it dii‘llcult
for the metal to be pulled through the narrow
or constricted die opening. Since the wall of the
tubing at the point of reduction Cv within the
_mouth of the die is materially weaker than at
75 anyupoint rearwardly thereof, I have found that
required stretch on the blank. It will be readily
seen therefore, that by virtue of the foregoing
the drawing operation is materially assisted. 20
The die isv relieved of considerable friction and
will‘consequently have a longer life. The fric
tional drag on the blanklis materially reduced
thus improving its surface characteristics and
reducing the power required for the cold draw 25
ing operation.
When the clamp or pulling head 3| reaches,`
during its forward travel, the die head 42, the
jaws of the clamp or gripping device 3| are auto
matically released by suitable automatic means, 30
not shown, thereby releasing the tubing» B and
permitting the rear terminal end to pass on
through the die opening.
I claim:
1. In an apparatus for reducing and elongating 35
a tubular blank, the combination of a die having
a restricted opening through which the blank is
drawn to reduce and elongate the same, separate
devices for continuously applying opposed forces
to said blank at opposite sides of said die, said
devices being relatively movable whereby adja
40
cent local portions of the blank at the locality
of the die are subjected to stretching action, and
a mandrel movable with the elongated portions of
the blank for controlling/the inner diameter
thereof and Acontrolling longitudinal strain there 45
on.
,
2. In an apparatus for reducing and elongating
a tubular blank, the combination of a die having
a restricted opening through which the blank is
drawn to reduce and elongate the same, separate 50
devices for continuously applying opposed forces
to said blank at opposite sides vof said die, said
devices being relatively movable whereby adjacent
local portions of the blank at the locality of the
die are subjected to stretching action, a mandrel
movable with the elongated portions of the blank
for controlling the inner diameter thereof, and
means for varying the pposing force exerted'by
' one of said devices.
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3. In an apparatus for reducing the wall thick
ness of a blank and elongating the same, the
combination of a die having a restricted opening
60
through which- a tubular blank of larger diameter
is drawn to reduce and elongate the same, means
exerting a longitudinal force on the’ blank for
drawing said blank through the die. means exert
ing an opposing force of less magnitude for
stretching the blank at the point of reduction
thereof in the die, and means for limiting said
stretching action to the locality of saidpoint of 70
reduction.
4. In an apparatus for reducing the wall thick
ness bf a blank and elongating thasame, the com- `
binaticn of a stationary die having an opening 75
z
3
2,108,790
said last named device for yieldingly resisting the
is drawn, a mandrel located interiorly of said travel thereof, and means for varying the resist
’
v
blank, a device adapted to be ¿attached to said « anceof said hydraulic means.
8.`In an apparatus of the class described, the
mandrel and bla'nk adjacent the forward end
thereof for drawing the> said mandrel and blank combination of a die having an opening through
through the die, and a device adapted to be at- - >which a tubular blank of larger diameter is
tached to the blank adjacent the rear end thereof drawn to reduce and elongate the same, la man- ' '
through which a tubularblank of larg-er diameter
'for resisting the travelo! the blank through the
die.
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5.' In an apparatusl for reducing the wall thick
ness of a blank and elongatingthe same, the com
bination of a stationary die> having an opening
through which a tubular blank of larger diameter
is drawn, a mandrel located interiorly of said
blank, a device adapted to be' attached to said
mandrel and blank adjacent the forwardy end
dreljlocated within said blank, a forwardly .travel
_ing pulling head adapted-to grip the forward
end of the blank and mandrel for pulling the 10
same through the die, a rear pulling head at
tachable at the rear end of the blank for resist
ing the forward travel of the blank, and an
hydraulic piston operatively connected to said
rear travelling head for applying a yieldable 15
force effective to resist but not prevent movement
thereof for drawing the said mandrel and blank
through the die, and a device adapted to be at
. tached to the blank adjacent Vthe rear end thereof
20 and movable therewith but at. a lesser rate of
of the blank.
ness of a. blank and elongating the same, the com
25 bination of a stationary die having an opening
bers being mounted to travel in the same direc
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A
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9. In an apparatus of thel class described, the
combination of a die having an opening through
which a tubular blank of larger diameter is drawn 20
speed than said first named device for resisting » to reduœ and elongate the same, pulling members
adapted to be operatively connected to the blank
‘the travel of the blank through the die.
6. `In an apparatus for reducing the wall thick vat opposite sides of said die, both of said mem
tion but at different rates of speed whereby said 25
blank will be progressively stretched at its 'point
through which a tubular blank of larger diameter
is drawn, a mandrel located interiorly of said of reduction in the die, and means for controlling
blank, a device adapted to be attached to said the internal diameterof the reduced portionsof
mandrel and blank adjacent the forward end f the blank and for limiting longitudinal' 'strain 30
30 thereof f_or drawing the said mandrel and blank thereon.
l0. In an apparatus for reducing and elongat
through the' die, a device adapted to be attached
ing
a tubular blank, the combination of a pair of
to the blank adjacent the rear end thereof and
movable'therewith but at a lesser rate of speed members adapted to be attached to the blank at
than said first named device for resisting the spaced points in its length and'mounted to travel
35 travel of the blank through the die, and means in the same direction, means for moving one of 35
for varying the resistance. force exerted by said said members at a greater rate of speed than the
other member thereby to exert longitudinal op
second named device. j
.
’7. In an apparatus for reducing the wall thick- ness of a tubular blank and elongating the same,
40 the combination of a die having an -opening
through which a tubular blank of larger diameter
Í,is drawn to reduce and elongate the same, a for
wardly travelling device for pulling the blank
through the die, a forwardly travelling device
45
adapted to be secured to the blank adjacent'the
rear end thereof, hydraulic means connected to
posed forces tending to stretch the blank inter-nl
mediate the members, and a die having an open
ing through which said blank is drawn for re
ducing the diameter and wall thickness of the
blank and effective to progressively weaken the
'blank at the point of the reduction thereof, and
meansv whereby the effective stretching of the
blank will be localized at said weakened point.
,
SIDNEY D. INSCHO.
40
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