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Патент USA US3032041

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May 1, 1962
G. GERARD ETAL
3,031,993
METAL-FORMING PRESS
Filed May 1, 1958
3 Sheets-Sheet 1
INVENTORS.
GEORGE GERARD 8
JACOB BRAYMAN
9M, m £19m
eir
ATTORNEYS.
May 1, 1962
G. GERARD ETAL
3,031,993
METAL-FORMING PRESS
Filed May 1, 1958
//
47
4%
/7
/7
FIG. 2.
GEORGE GEIQXRJZIDNTgRS'
JACOB BRAYMAN
“ EY
May 1, 1962
G. GERARD ETAL
3,031,993
METAL-FORMING PRESS
Filed May 1, 1958
3 Sheets-Sheet 3
CONTROL
UNIT
-------------------- "r --------------- "1
A?
INVENTORS.
GEORGE GERARD 8|
FIG_5_
BY JACOB BRAYMAN
?wlzdim?méw
their
ATTORNEYS.
United States Patent 0
3 3,031,993
Patented May 1, 1962
2
1
3,031,993
apparent from a reading of the following description in
conjunction 'with an examination of the accompanying
‘
METAL-FORMING PRESS
George Gerard, Yonkers, and Jacob Brayman, Staten
Island, N.Y., assignors to Engineering-Supervision Com
drawings in which:
FIG. 1 is a side view showing a vertical section through V
a typical deep draw rubber pad press arranged according
to the invention with the press platens in the open posi
pany, New York, N.Y., a corporation of New York
Filed May 1, 1958, Ser. No. 732,311
13 Claims. (Cl. 113-44)
tion;
‘
FIG. 2 is a side view showing the rubber pad press of
FIG. 1 in the closed position;
This invention relates to rubber pad deep draw metal
presses and, more particularly, to a new and improved 10 ' FIG. 3 is a view of the press in horizontal section, taken
on the lines 3—3 of FIG. 2;
rubber pad press adapted to utilize the space available
FIG. 4 is a view similar to that of FIG. 1 illustrating
between the press platens to maximum advantage.
In metal-forming presses having two spaced platens
the rubber pad press adapted for use with a smaller die;
which are adapted to move toward each other and exert
and
a high compressive force on objects positioned between 15
'
.
FIG. 5 is a schematic view illustrating a typical hy
draulic press control system arranged according to the
invention.
As shown in FIGS. 1, 2 and 3, a representative rubber
pad press according to the invention comprises an upper,
them, the platens usually have a limited maximum'separa
tion, thus restricting the available space or “daylight”
wherein the metal-forming equipment can be mounted.
In order to adapt such presses for rubber pad operation,
a male die is mounted on one platen and a rubber pad'on 20 assembly 10 and a lower assembly 11 mounted on an
the other so that a metal blank positioned between the
upper platen 12 and a lower platen 13, respectively, of
die and the pad is forced against the die and formed by
a conventional press machine. The usual drive apparatus
it when the two platens are moved together.
(not shown) is arranged to drive the two platens together
'
with a high compressive force, the upper platen 12 being
In order to prevent wrinkles, rough surfaces, and varia
tions in the thickness of metal pieces formed in this man 25 vertically movable and the lower platen 13 being ?xed,
for example. Supported from the upper platen, as by
ner, it is necessary to support the portion of the metal
clamps 14, the upper assembly 10 includes a rubber pad
blank surrounding the die against the rubber pad in a
holder 15 containing a typical rubber pad 16 comprised
controlled manner while the rubber pad is pressed against
of a series of layers of rubber, Mounted by clamps 17
the die. A variety of back-up structures mountable in
metal-forming presses have been devised to provide the 30 on the lower platen 13 directly beneath the upper assem
bly, the lower assembly 11 includes a housing 18 having
necessary support, but all of the presently known devices
a recessed upper periphery 19 arranged to receive the pad
are complex in design and occupy a substantial portion
holder 15 when lowered, as best seen in FIG. 2.
of the available space between the platens. For example,
Within the housing 18, a base plate 20 lies on the lower
many conventional rubber pad units support the metal
die on a crosspiece spaced from the lower press platen 35 platen 13 and a block 21 extends upwardly therefrom to
support a male die 22 in spaced relation to the platen 13,
and include a hydraulic cylinder arrangement between
the die being positioned on the block 21 by suitable locat
the crosspiece and the platen, adapted to‘ exert a force
ing pins and‘ keys ‘(not shown). Surrounding the support
against the portions of the metal blank surroundinglthe
block 21, an endless inner‘channel 23 slideably receives-in
die. In this case, the crosspiece must be thick enough
to Withstand the high pressures of ‘the press while ‘the 40, ?uid-tight relation a complementary-shaped piston mem
ber 24 which forms a closed loop about the block 21.
space beneath must be large enough to permit motion
Spaced outwardly from the inner channel 23 by a vertical
of a piston within the cylinder arrangement from one
extreme position to the other.
‘ septum 25, an endless outer channel 26 has a comple
‘ I
mentary piston member‘ 27 slideably supported therein
Accordingly, it is an object of this invention to provide
a new and improved rubber pad press arranged to’ occupy 45 in the same manner, the spaces between each channel and
its piston member being sealed by suitable chevron-type
a minimum fraction of the distance between the platens.
Another object of the invention is’to provide a press I packing rings 28 held in place by clamping members 29.
of the above character having a new and improved struc
It will be observed that if the male die has a large base
ture for applying back-up pressure to support the material
area, as does the die 22 shown in FIGS. 1 and 2, the outer
around the die.
50 portion of the die extends above the inner channel 23 to
I
A further object of the invention is to provide a new
the top of the septum 25, and, in this case, the inner
and improved system for controlling the back-up pressure
- piston member 24 is kept inoperative. In order to pro-,
in a rubber pad press.
vide direct support for the periphery of large diespof, this
’ _
These and other objects of the invention are accom
plished by forming a die mount housing with 'a die sup
port block extending ‘directly from one platen to the die
support position. Surrounding the support block,"a con
55
type, the septum 25 is a rigid member of su?icient thick
ness to [transmit the force of the press from the base plate ,
20 to thedie 22 without deformation, and preferably has
tinuous channel‘ in the housing receives a piston member
' the same height as the support block 21. It will be ap
' parent that, in presses not intended to utilize small size
of complementary shape operable by hydraulic pressure
dies, the inner channel 23 and the piston member 24 may
supplied to the bottom of the channel to support the por 60 be omitted from the housing 18. Inasmuch as many
tions of a material being formed around the die. In one
commonly'used dies have a base of generally circular
embodiment of the invention, the piston member is keyed
con?guration, the channels 23 and 26 and the piston
by shoes to the inner and outer surfaces of the channel
members 24 and 27 are preferably annular in shape, as
and the material being formed is supported at thetop of
best seen in FIG. 3,,vbut it will be understood that chan
65
nels and piston‘ members of other shapes may be more‘
the piston by rollable load transfer members, In addi
suitable for ‘use with dies having different base con?gura
tion, a second continuous piston member surrounding
the ?rst may be mounted in a second channel to support
tions. ;
I’
,
1
.
In order'to ‘guide the piston members'during vertical
the outer portions of a material being vformed by a die
of larger base area which extends over. the ?rst piston 70 motion within the channels and prevent cocking under
‘eccentric loads, the channel 26 is formed with shoes 30
member.
'
‘
Further objects and advantages‘ of the invention will be: . projectingfrom its inner and outer surfaces which ?t into
9,031,993
3
complsmentary-shapsd recesses in the. piston member to’
4
during the. compression When drawing relatively simple
permit vertical motion thereof but inhibit angular motion
face. Mounted at the top of the inner piston member
shapes, utilization of either of these methods may be suf?—
cient to prevent wrinkling and thickness variations. How
ever, for complex die shapes both these controls are
24, a series of vertical pins 31 extends to a point just be
low the top of the block 21 and the septum 25 when the,
metal to the die at the proper rate at each position dur
and the channel 23 has similar shoes 30 on its outer sur
necessary to assure feeding of the correct amount of
piston is in its lower. position, while a similar series of
ing the downward stroke of the upper platen.
‘pins 32 is supported on the outer piston member 217,
At the top. of each. of these Pius the end surface is suit;
vention includes a‘speed‘ and pressure control system of '
bacle-up plate ‘34 having a recess 35' is supported by the
plurality of balls, thus transmitting to the piston member;
vertical components of force but not horizontal com
press assembly 10 during its motion toward the lower
Accordingly, apparatus arranged‘ according to the in
ablyfformed to receive 'a load transfer ball 33 and a 10 the type illustrated schematically in FIG. 5. As indicated
therein, the speed of the upper platen 12 and the upper
assembly 11 is controlled in a predetermined manner at
each platen position by a controlunit 48 linked to the
ponents which might cause angular de?ection or cocking
thereof. Inasmuch as the large size die 22, shown in
15
FIGS. 1 and 2, extends over the inner channel‘23 not load
transfer balls are illustrated therein on the pins 31, the
power press (not shown) driving the platens together.
This unit may be, for example, of the type described in
the copending US. application Serial No. 714,639, ‘?led
February :11, 1958 now’ abandoned, which regulates'the
inner piston 24 being inactive. In order to contain the
rubber pad 16; within its holder 15 during compression,
speed of the platen 12 in a predetermined manner as a
the back-up member 34 has an internal contour ‘comple 20 function of its position'according to the contour of a
particular die.
'
mentary to that of the base of the die 22 while its out
7 side diameter ?ts within theyinside diameterv of the pad
In order to control the beck-up. pressure, the pressure
holder 15.
line 46 to the outer channel 26, which may have a pres
’
Leading to the bottom of the outer channel 26 a duct
sure gauge 49 connected theretol leads through a throttle
36 in the housing ‘18 conducts hydraulic ?uid ‘under
valve’Stl and a stop valve 51 to a low pressure hydraulic
line 52. Bypassing the throttle valve 5%), a unidirectional
valve 53 permits hydraulic ?uid to flow toward the lower
assembly 11; to. raise the outer piston member 27 but
blocks fluid flow in the other direction. From the inner
piston 27-, in its raised position, extends only a short dis‘ 30 channel, the hydraulic line 47, which also has a pres-.
sure gauge 49, is linked to the line 46 through a stop
tance into, the channel 26 when the back-up plate 34 sup,v
valve ‘54 and ?uid may be emptied from the system by
ports a sheet metal blank 38_level with the top surface
opening a drain valve 55 in the line 47, Each of the
of the die 22, while, in its lowered position as shown
in FIG. 2, the upper portion of the formed blank is held
valves '51,, 54 and 55 may, for example, be a solenoid
adjacent the base of the die 22. Accordingly, in presses 35 valve actuable by electrical signals received through each
pressure thereto from a line 46 to a raise the piston 27
to its top position as shown in FIG. 1. Similarly, a duct
37 connected to a pressure line 47 leads to the bottomv
of the inner channel 23. As illustrated in FIG. 1,, the
oipthree conductors 56, 57 and 58, respectively, While
constructed according to the invention the height of the
block 21 and the septum 25 need be only a little greater
the throttle valve is operated by- an electric motor 59
in response to the voltage between a pair of conductors
than the maximum height of the die 22.
.
60 and 60:; leading from a pressure vs’. stroke controller 61.
As illustrated in FIG. 4, a rubber pad press arranged
according to the invention may be adapted to utilize _a_ 40 As‘ shown in 131G. 5, a typical pressure vs. stroke con
troller 61 mayinclude a rotary cam 62' turned by mo
small size male die 39 having a base no’ larger than the, '
top, of the block 21 byv supporting a smaller back-up plate
tion of therplaten v12 through a‘ mechanical linkage 63
4401 with a coupling member. 41 mounted on both‘ the
1 and formed with a'varying radius which is proportional
to. the back-up pressure required at the corresponding
diameter back-up plate 40' has an internal aperture con: 45 position of the platen in its downward‘ stroke as deter
mined by the shape of the die taking into account the
formingto the .contour of the .base of the die 39, the
inner and'outer'piston members 24. and 2.7. This smaller
?uid velocity generated by the speed of the platen during
coupling member 41 being“ supported by load transfer
balls 33 on both the series of pins 31 and 32. With both
that portion of its stroke. In response to variations in
piston members raised, the top surface of the back-up
the radius, ofthe cam 62,, a spring-biased cam follower
plate 40‘ is level with the top of the die 39 and- supports 50 64v drives the movable tap 65 of a potentiometer 66 con
the outer portion of a metal blank 42, while in the low
nected between positive and negative voltage sources, the
ered position the top of the back-up plate is level With
tap 65 being electrically joined to the motor control con
the base of the die, which is supported on the block
doctor 60. Another potentiometer 67, is also connected
21 by a spacing member 43. Inasmuch as the area of
the metal blank 42 to be drawn by. the smaller die 39. is
considerably less than that of the pad holder 15,_ an an
between positive and negative voltage sources and has a
55
nular reducing‘ ring 44 is mounted within the padholder
15 and a smaller rubber pad 45 is inserted in the holder.
In order to maintain ahi'gh pad pressure, the back-up
plate 40. is shaped to receive the ‘inside diamter of the
reducing ring 44 when lowered, thereby restricting the ._
60
movable tap 68; linked to the conductor 666;, the tap 68
being driven by a spring-biased plunger 69 responsive to
changes in the ?uid pressure in a ‘line- 70 connected to
the line;46_. Thus, the motor 59, which may be any con
ventional type, adapted to close the throttle 50 when
the conductor 60 is negative with respect to the conductor
60a and open the‘th'rottle when‘ the, conductor 64} is posi- - '
rubber pad 45 within the con?nes of the holder- 15.
tive with respect to the conductor 6%, maintains the
Inthe process of forming a metal blank with a male
die in a rubber pad press,’ it is essential that the Proper
throttle at any given position as long as’ the pressure in
the. line ‘Z0, is the same as that indicated by the cam fol
amount of‘ metal from the blank be fed to-the die at each
moment during the drawing operation to prevent wrin
kling of the ?nished surface and variations of- metal thick
ness. in the formed piece.v One method of obtaining this
65
lower 64, thereby holding the taps, 65' and 68 at the same
potential. Thereiore, as long- as the pressure in the line
70 is. the same as that represented by the cam radius (and,
this will be indicated by equality of the potentials on the
lines 60,, and 6.0a), the throttle 58 will remain in the same
at‘ each position in its downward motion according to a. 70 position. ‘It, because of an increase in ?uid velocity, for
example, the pressure in the line 70 riseslabove the de
. precise program wherein the speed is a .function of'the
shape of the die. In addition, the metal‘supply may also
sired value, this‘ will be detected by the Plunger. 6.9 and,
result is by controlling the speedof the movable platen
be regulated by appropriately’ controlling the pressure oi
the backup. plate supporting the surrounding. Portion of
" the potentiometer 67 will apply voltage to drive the motor
59. in the proper direc on to open the throttle 50 and
the metal blank against the rubber pad at each position 75 reduce the‘pressure to the desired value.
3,031,993
5
6
- ‘In operation, withthe platen 12 raised and the lower
' Although the invention has been described herein with
reference to a speci?c embodiment, many modi?cations
and variations therein will readily occur to those skilled
drain valve 55 is closed and the stop valve 51 is opened
in the art. Accordingly, the invention is not to be limited
to supply ?uid to the line 46 under low pressure through
the bypass valve 53. If a large size die 22 is used the 5 to the exact details of construction shown and described.
I We claim:
valve 54 is kept closed to prevent ?uid from reaching the
assembly in position beneath the upper assembly 10, the
inner channel 28, and the large diameter back-up plate
' 1. Metal-forming apparatus for use in a press having
34 is supported on the pins 32 of the outer piston 27.
Fluid entering the outer channel through the line 46 raises
the outer piston to its top position, as shown in FIG. 1,
and a metal blank 38 is placed over the die and the back
two spaced platens arranged to be driven toward each
other by a high compressive force, one of the platens
having a rubber pad mounted thereon, said metal-form
ing apparatus comprising a housing adapted to be mount
up plate. As the upper assembly 10 is brought down
over the die, its speed is regulated in accordance with
the contour of the die by a predetermined program set
ed on the other platen including die support means ex
tending directly between a die position and the other
platen, channel means surrounding the die support means
into the control unit 48 as described above. At the same 15 and'within the housing, piston means slideably supported
time, the outer piston 27 is pressed downwardly into the
outer channel 26, forcing the hydraulic ?uid therein out
through the line 46 and the throttle 50 into the low pres
in the channel means in ?uid-tight relation therewith,
back-up means supported on the piston means and mov
able therewith between a position adjacent the top of a
die mounted on the support means and a position adja
sure line 52. Inasmuch as the bypass valve 55 blocks
?uid ?ow in this direction the rate of ?ow, and therefore 20 cent the base of the die, and rollable load transfer means
the force exerted by the back-up plate 34- pressing the
metal blank 38 against the rubber pad 16, is determined
by the setting of the throttle 50.
,
interposed between the piston means and. the back-up
means and supporting the back-up means on the piston
means to transmit components of force parallel to the mo
As previously mentioned, the pressure vs. stroke con
tion of the piston means and prevent transmission of com
with a program determined by the shape of the cam 62
which is based on the shape of the die 22 so that the
proper amount of metal is fed to the die at each position.
It will be apparent from an examination of FIG. 5 that
decreased pressure in the line 70 lowers the plunger 69
so that the tap 65 of the potentiometer 67 becomes more
two spaced platens arranged tobe driven toward each
other by a high compressive force, one of the platens
having a rubber pad mountedthereon, said metal-form
ing apparatus comprising a housing adapted to be mount
troller 61 regulates the back-up pressure inaccordance 25 ponents perpendicular thereto.
positive. Similarly, depression of the cam follower 64 by
an increase in cam radius moves the tap 65 to a more
negative portion of the potentiometer 66. In each case,
the motor 59 is actuated by the potential difference be
2. Metal-forming, apparatus for use in a press having
ed on the other platen includingdie support means ex
tending directly between a die position and the other
platen, ?rst channel means in the housing surrounding the
die support means, piston means slideably supported in
the ?rst channel means in ?uid-tight relation therewith,
second channel means surrounding the ?rst channel means
tween the conductors to close the throttle 50, thus raising
and separated therefrom by a septum extending from
the pressure in the line 76 until the conductors 6t} and
the base of the housing to the die support position, piston
60a are again at the same potential. On the other hand,
means slideably supported in the second channel means
increased pressure on the plunger 69 or decreased radius
in ?uid-tight relation therewith, and back-up means sup
40
of the cam 62 moves the element 64 or 69 in the opposite
ported on-the ?rst and second piston means and movable
direction to prodtiée a potential diiference in the opposite
therewith between a position adjacent the top of a die
direction, opening the throttle 50. It will be readily ap
supported on thedie support means and'the septum and
parent that, for optimum operation of the system, the
a position adjacent the base of the die.
.
cam 62 should be advanced with respect to the position of
.3. Apparatus according tolclaim 2 wherein each of
the platen 12 by an amount equal to the reaction time 45
the channel means and piston means is annular in shape.
of the system in order to assure the proper back-up pres
4.}Metal-forming apparatus for use ina' press having
' sure in the channel 26 as the platen reaches each position
two‘ spaced platens arranged to be driven toward each’
in its downward stroke.
other by a high compressive force, one of the platens
After the downward stroke has been completed as il 50 having a rubber pad mounted thereon, said metal-form
lustrated in FIG. 2, the upper platen 12 is raised and,
ing apparatus comprising a housing adapted to be mount
if the space between the die and the upper assembly 10
ed on the other platen including die support means ex
is insu?icient to permit removal of the formed piece the
tending directly between a die position and the other
- lower assembly may be withdrawn from beneath the up
platen and ?rst channel means surrounding the die sup
per, assembly to extract the formed metal. Actuation 55 port means and within the housing, piston means slide
of the valve 51 to supply ?uid pressure to the outer cylin
ably supported in the ?rst channel means in ?uid-tight
der 26 will assist in removing the work piece from the die
relation therewith, second channel means surrounding the
by jogging the outer piston member and the back-up plate.
?rst channel means and separated therefrom by a septum
When the piece has been removed the valve 51 may be
extending from the base of the housing to the die support
closed and the lower assembly 10 is replaced beneath the
position, piston means slideably supported in the second
upper assembly 11. If desired, the outer piston member
channel means in ?uid-tight relation therewith, a back-up
27 can be lowered when’ the stop valve 51 is closed by
plate supported on the second piston means and movable
opening the connecting valve 54 and the drain valve 55.
therewith between a position adjacent the top of a die
supported on the die support’ means and the septum and
The forming of metal blanks with a small size die 39
is carried out in a similar manner with the coupling plate 65 ‘a position adjacent the base of the die, and rollable load
41_supporting,the back-up plate 40 on both pistons 24
and 27, the reducing ring 44 and the smaller rubber pad
45 being inserted in the pad holder 15. In this‘ case, the
connecting valve 54 is opened along with the stop valve
51, permitting hydraulic ?uid to pass through both the 70
lines 46 and 47 to raise vboth piston members to" their‘ top
transfer means interposed between the ,second piston
means and the back-up plate and supporting the back-up
plate on the second piston means to transmit components
of force parallel to the motion of the piston means and
prevent transmission of components perpendicular there
to.
a
positions, as shown in FIG. 4. During the downstroke
5. Metal-forming apparatus for use in av press having
the connecting valve 54 is held open so that the throttle
two spaced platens arranged to be driven toward each
50 regulates the pressure in both the channels 23 and 26
other by a high compressive force, one of the platens
in the manner described above.
75 having a rubber pad mounted thereon, said metal-forming
3,031,993
.
,
7
,
8
.
other by a high compressive force, one of the platens
having a rubber pad mounted thereon, said metal-form
ing apparatus comprising a housing adapted to be mounted
apparatus comprising a housing adapted to be mounted
on the other platen including die support means extend
ing directly between a die position and the other platen
and ?rst channel means surrounding the die support
means and within the housing, piston means slideably
supported in the. ?rst channel means in ?uid-tight rela~
tion, therewith, second channel means surrounding the
on the other platen including die support means extend
ing directly between a die position and the other platen
and ?rst channel means surrouding the die support means
and within the housing, piston means slideably supported .
in the ?rst channel means in ?uid-tight relation therewith,
second channel means surrounding the ?rst channel means
?rst channel means and separated therefrom by a septum
extending from the base of the housing to the die sup:
and separated therefrom by a septum extending from the
base of the housing to the die support position, piston
port position, piston means slideably supported in the
second channel means in ?uid-tight relation therewith,
and a back-up plate supported on the ?rst and second
piston means ‘and movable therewith between a position
adjacent the top of a die supported on the die support
means and a position adjacent the base of the die.
means slideably supported in the second channel means
in ?uid-tight relation therewith, a ?rst ?uid conduit lead
ing from the second channel means, a second ?uid con
15 duit leading from the ?rst channel means joined to the
?rst ?uid conduit through a stop valve, adjustable throttle
6. MetaLforming apparatus for use in a press having
two spaced platens arranged to be driven toward each
other with a high'compressive force, one of the platens
means connecting the ?rst ?uid conduit to a low pressure
source, throttle control means for varying the setting of
the throttle means in a predetermined manner in response
having a rubber pad mounted thereon, said metal-forming
apparatus comprising a housing adapted to be mounted
to relative motion of the platens, and pressure-sensitive
means adapted to regulate the throttle control means in
on the otherplaten including die support means extends
accordance with the ?uid pressure in the ?rst conduit.
11. In apparatus for controlling ?uid back-up pressure
ing directly between a die position and the other platen,
channel means surrounding ‘the die support means and
within the housing, piston means slideably supported in
in a press in a predetermined manner in response to rela
mounted on the support means and aposition adjacent
the base of the die, a ?uid conduit leading from the chain
means at a pressure higher than that of the source in re
means in a predetermined manner in response to relative ~
throttle in a predetermined manner in response to rela
the channel means in ?uid-tight relation therewith, a 25 tive motion of the press platens, conduit means leading
‘ from the press ‘to a low pressure ?uid source, back-up
back-up plate supported on the piston means and movable
piston means connected to drive ?uid through the conduit
therewith between a position adjacent the top of a die
sponse to relative motion of the press platens toward each
nel means, adjustable throttle means in the conduit, throt 30 other, adjustable throttle means in the conduit means,
throttle control means for varying the setting of the
tle control means for varying the setting of the throttle
tive motion of the platens, and pressure-sensitive means
motion of the platens, and pressure-sensitive means adapt
adapted to regulate the control means in accordance with
ed to regulate the control means in accordance with the
35 the back-up pressure in the press.
?uid pressure in the channel means.
12. In apparatus for controlling ?uid back-up pressure
7. Apparatus according to claim 6 wherein the, ?uid
conduit leads from the throttle means to a low pressure
?uid source and including a unidirectional valve in paral
lel with the throttle means permitting ?uid to ?ow from
the‘source toward the channel means.
‘
in a press in a predetermined manner in response to rela
tive motion of the, press platens, conduit means leading
from the press to a low pressure ?uid source, adjustable
40 throttle means in the conduit means responsive to an
8. Metal-forming apparatus for use in a press-having
two spaced platens arranged to be driven toward each
other by'a high compressive force, one of the platens
having a rubber padw mounted thereon, said metal-form
ing apparatus comprising a housing adapted ‘to be 45
mounted on the other platen including die support means
extending directly between a die position and the other
platen, channel means surround-ing the die support means
and within the housing, piston means slideably supported
in the channel means in ?uid tight relation therewith, a
back-up plate supported on the piston means and movable
therewith between a position adjacent the top of a die
mounted on the support means and a position adjacent
the base of the die, a ?uid conduit leading from the
channel means, adjustable throttle means in the conduit
responsive to an electrical control signal, potentiometer
means having a movable tap linked to the throttle means
electrical control signal, poteniometerg means having a
movable tap linked to the throttle means and generating
a control signal, cam means for driving the movable tap
in‘ response to relative motion of the platens having a
surface which is a function of the required back-up pres
sure, and pressure-sensitive electrical means responsive
to the back-up pressure in the press adapted to vary the _
throttle means in accordance with changes in the back-up
pressure.
'
13. Apparatus according to claim 12 wherein the pres
sure-sensitive means includes a potentiometer generating
a second control signal adapted to balance the control
signal from the cam-driven potentiometer means when.
the ?uid pressure has a‘ predetermined relation to the
cam means.
-
References Cited in the ?lev of this patent
UNITED STATES PATENTS
and generating a control signal, cam means for driving
the movable tap in response to relative motion of the
platens having a surface which is a function of the shape
ofthe die, and pressure-sensitive electrical means respon
sive to the ?uid pressure in the channel means generating
a second control signal in accordance with changes in
the ?uid pressure in the channel means,
1,893,951
Kuhner _.___' __________ __ Jan. 10, 1933
2,075,847
Hothersall ____________ __ Apr. 16, 1937
495,591
Knight et al ___________ __ Apr. 18, 1893
1,080,482
Roberts ______________ ..._ Dec. 2, 1913
1,240,791,
Czajka _____________ .._. Sept. 18, 1917
9. Apparatus according to claim 8 wherein the PICS?
2,192,778
Stacy ________________ .__ Mar. 5, 1940
sure-sensitive means includes a potentiometer adapted to >
2,375,599
Walton ______________ __ May 8, 1945
generate a second control signal balancing the ?rst, when
2,390,359
Ernst ________________ __ Dec. 4, 1945
thel'?uid pressure has a predetermined relation to the cam
2,403,339‘
Byerlein ______________ __ July 2, 1946
means.
2,605,731
2,783,728.
_ Schulze et a1. _________ __ Aug. 5, 1952
Hoffman _____________ __ Mar. 5, 1957
10. Metal-forming apparatus for use in a press having
two spaced platens arranged to-be driven toward each
2,917,066 '
Bergson ______________ __ Dec. 15, 1959
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