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Патент USA US3027161

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March 27, 1962
F. M. WILLIAMSON
3,027,151
HYDRAULIC CONTROL SYSTEM FOR DIE PADS IN PRESSES
Filed D60. 2, 1960
2 Sheets-Sheet 1
N.“
March 27, 1962
F. M. WILLIAMSON
3,027,151
HYDRAULIC CONTROL SYSTEM FOR DIE PADS IN PRESSES
Filed Dec. 2, 1960
2 Sheets—Sheet 2
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Patented Mar. 27, 1962
1
2
3,027,151
control circuit for the die pad of a ram type press; and
FIG. 2 is a view similar to FIG. 1 illustrating a modi
HYDRAUMC CGNTRU'L SY?TEM FER DEE
PADS IN PRES?ES
Floyd M. ‘Williamson, 2405 E. Grand Blvd,
Detroit 11, Mich.
Filed Dec. 2, 1960, Ser. No. ‘73,272
6 Claims. (Cl. 267ml)
?ed form of the invention.
In FIG. 1 there is illustrated a porLion of a crank
type press ll) which includes a ram 12 driven by a
crank in a conventional manner and carrying an upper
die 14, and a lower die shoe 15 mounted on a bolster
This invention relates to mechanical presses of the
18 and carrying a die pad it? which is vertically recip
rocable in the die shoe 16. The bolster 18 is provided
ram type employing a movable die pad which is engaged
with one or more cylinders 22, each having a piston
by one or more hydraulically controlled pistons for mov
24 reciprocable therein and engaging the underside of
the die pad 2%}. The bolster is provided with a passage
ing the die pad to an extended position on the return
stroke of the ram and which pistons resist movement
of the die pad to its retracted position during the work
ing stroke of the ram. The invention is more particu
larly directed to a hydraulic control system for con
trolling the ?ow of hydraulic ?uid to and from the cyl
inders containing the pistons which engage the die pad.
in my Patent No. 2,842,357, issued July 8, 1958, I
26 which is connected by a conduit 28 to a valve as
sembly including body 3%.
The valve body 30 is provided with a passage 32
connected to the conduit 28 and terminating in a cavity
or recess 34 containing a check valve 36 which engages
a valve seat 38 and is urged against the valve seat 38
by a spring 4!). A passage 42 leads from the valve
have disclosed a hydraulic control system for the die 20 seat 38 to a passage 44 communicating with a conduit
46 connected to a supply tank 43 which contains a quan
pads of a ram type press. The present invention is an
tity of hydraulic ?uid under pressure (for example, 100
and provides a greatly simpli?ed and less expensive valve
lbs. p.s.i.).
The valve includes a passage 5t? which intersects the
arrangement for controlling the flow of the hydraulic
?uid to and from the working cylinders. in hydraulic 25 passage 32 and communicates with a valve chamber 52
improvement over the system disclosed in such patent
containing a pressure relief valve 54 which is adapted
circuits of this type it is important to circulate at least
to close the passage 5i} under the in?uence of a spring
a part of the hydraulic ?uid through the supply tank
56 which is backed up by an adjusting screw 53 threaded
during each cycle of the press in order to prevent over
into a plug 60 which closes the upper end of the valve
heating of the ?uid and the valve and passages. Heat
ing of the liquid can also be minimized by reducing 30 chamber 52. A passage 62 communicates with the valve
chamber 52 on the downstream side of the pressure relief
the velocity at which the hydraulic ?uid ?ows through
valve 54 and communicates with a conduit 64-, which is
the lines and valve passages, and the present invention
has as its object the provision of a hydraulic system of
also connected to the supply tank.
A passage 66 forming an extension of the passage 42
this type which is designed to obtain circulation of a
part of the oil through the supply tank at each stroke 35 communicates with a passage 68 which intersects the
passage 62 past a check valve 7%‘, which is engaged by a
of the press and to reduce the velocity of ?ow of the
spring '72 reacting against an adjusting screw 74. In
?uid so as to reduce the heat resulting from friction
the idle position of the press, check valve 78 has tank
due to the ?uid ?ow through the system. It is desirable
pressure applied on both sides, plus a spring tension
to use hydraulic lines as small as possible because of
(applied by spring '72) considerably less than tank pres
their ?exibility to move with the motion of the die. Large
lines are cumbersome and present an obstruction.
sure.
A principal object of the invention is to provide a
new and improved hydraulic control system for die pads
pressure from the tank 48 during the return stroke of the
Each cylinder 22 is ?lled with hydraulic ?uid under
press through conduit 46, passages 44 and 42, past check
Another object of this invention is to provide a sys 45 valve 36, and through passage 32, conduit 28, and pas
sage 26. When the ram 12 descends during the working
tem in which it is possible to use smaller lines from
stroke of the press, the die pad 2% is forced downwardly
the tank by allowing the oil to ?ow through a plurality
against the piston 2a (or pistons, as the case may be)
of lines to the tank during the small portion of the
in ram type presses.
cycle when the velocity is very high.
Another object of the invention is to provide a con
trol system of the type described which is comprised of
a minimum number of parts to reduce the cost and
increase the dependability thereof and which makes pos
sible the use of relatively small diameter ?uid conduits.
A further object of the invention is to provide a hy
draulic control system of the type described which pro
vides additional passage area for the ?ow of ?uid to and
which resists such movement of the die pad to an extent de
termined by the pressure at which the pressure relief
valve 54 is set to open. When the die pad retracts, the
pressure ?uid is forced out of the cylinder 22 through
conduit 23 into passage 5%, and when the pressure exceeds
a predetermined amount, the pressure relief valve 54
55 will open to allow the fluid to return to the supply tank
48 through passage 62 and conduit 64 at a portion of the
cycle when the velocity of the displaced hydraulic ?uid
from the supply tank during certain portions of the
is very high.
The rate at which the pressure ?uid is expelled from
cycle of the press, thereby reducing the ?ow velocity of
the ?uid and eliminating excessive heating in the system. 60 the cylinder 22 (or cylinders, as the case may be) is
proportionate to the rate of closing movement of the ram
Other and further objects of the invention will be
12. Since the ram is driven by a crank, its downward
apparent from the following description and claims and
movement will be at a greater speed when the crank
may be understood by reference to the accompanying
drawings, of which there are two sheets, which by way
of illustration show preferred embodiments of the inven
tion and what I now consider to be the best mode of
arm is horizontal and will be gradually slowed as the
ram reaches the lower limit of its travel. The passages
66 and 68 and the check valve 70 constitute a means for
applying the principles thereof. ‘Other embodiments of
providing additional passage area (through passage 46)
for the ?ow of ?uid back to the tank during the working
the invention may be used without departing from the
scope of the present invention as set forth in the ap
pended claims.
In the drawings:
FIG. 1 is a schematic view illustrating a hydraulic
stroke of the press when the pressure on the ?uid is the
70 greatest. The increase in the passage area past the valve
54 reduces the velocity of the ?uid ?ow, thereby reduc
ing friction and the heat generated thereby. As the ram
3,027,151
3
4
reaches the lower end of its travel, its speed is decreased
providing an additional passage area for the return of
to the point where the pressure on the ?uid is reduced
pressure ?uid to the cylinders 108 during a portion of
sufficiently so that valve 70 will close and the remaining
pressure ?uid will be forced out through the conduit 64
into the tank.
When the ram begins its return stroke, the valve 711
will be closed and the pressure within the tank 48 will
force the hydraulic ?uid through conduit 46 and passages
44 and 42 past check valve 36 to the cylinder 22. The
the cycle when the ?uid velocity is highest.
The valve 116 shown in FIG. 2 is the same as the
valve 30 shown in FIG. 1, except that it has a time de
lay valve incorporated therein to delay return move
ment of the die pad to its extended position upon open
ing of the press. The time delay valve comprises a spool
valve 152 which is slidable within a bore 154 and urged
ram travels upwardly at an increasing rate of speed as 10 toward the right-hand end of the bore by a spring 156
the crank arm moves toward its horizontal position and
which is con?ned between the valve 152 and an adjust
the piston 24 is therefore free to travel upwardly at a
ing screw 158. A portion of the pressure ?uid ejected
greater speed. It is desirable in some cases that the pad
from the cylinders 108 upon closing of the press and
?owing through passage 121} will be supplied to the bore
20 follow the ram as it returns so as to strip the work
from the lower die and to minimize the possibility of the
154 through a passage 160 past a reduced diameter por
pad cocking. Hence when and if the pressure in the lines
tion 162 of the valve 152 to passages 164 and 168 to a
66, 32 and 28 drops as the ram moves up, tank pressure
passage 170 which leads to the right-hand end of the
exerted on check valve '70 through lines 64 and 68 un
valve bore 154 to shift the spool valve 152 to the left
seats valve 70 allowing oil to ?ow from lines 64 and 68
until it closes the passage 126.
past valve 70 into lines 66 and 32, thus maintaining the 20
After the ram has completed its working stroke, the
pressure on piston 22 to cause the pad 20 to follow the
return of ?uid to the cylinders 108 will be delayed due
ram to the extended or upper position of the pad 20.
to the fact that the passage 126 is closed by the valve 152
The valve 70 closes when the cylinders 22 are ?lled, and
and will remain closed until the ?uid in the right-hand
a new cycle of operation begins.
end of the valve bore 154 is forced out through passage
The invention is schematically illustrated in FIG. 2
170 past a bleeder valve 172 into passage 126 ahead of
in a hydraulic control circuit including a time delay valve
the check valve 128. As soon as the time delay opens
for delayingreturn movement of the die pad after the
the passage 126, the pressure ?uid will be returned to
ram has completed its working stroke. In this embodi
the cylinders 168 through the conduits 134 and 150 in
ment of the invention the ram 11%} engages the work
the manner described. The time delay valve disclosed
102 which rests upon the die pad 104 engaged by pistons
herein forms the subject matter of my Patent No. 2,901,
a
106 working within cylinders 198. Any suitable number
of pistons 106 and cylinders 168 may be used. The
conduit 110 communicates with each of the cylinders 103
23 8, issued August 25, 1959.
It will be apparent that the valve arrangement disclosed
herein is very simple in construction and requires only
three separate valves and a minimum number of pas
sages in order to obtain the desired results. By employ
through an air bleed tube 112 or 114, which may be
similar toithose disclosed in my Patent No. 2,924,446,
issued February 9, 1960. The piston and cylinder ar
ing two conduits connecting the supply tank to the valve
rangement need not he of this particular type and may be
body and a single conduit connecting the valve body to
of any suitable construction.
the working cylinder, the conduits’ lengths are greatly
vA valve body 116 is provided with a port 113 com
reduced and smaller lines can be used, which enables
municating with the conduit 110 and a second port 12% 40 more of the hydraulic ?uid tot be circulated back to the
which communicates with the conduit 116 through a
supply tank at each cycle of the press.
branch line 122. A passage 124 communicates with the
While I have illustrated and described preferred em
port 118 and intersects a passage 126 which is provided
bodiments of my invention, it is understood that these
with a check valve 128 which normally closes the pas
are capable of modi?cation, and I therefore do not wish
sage 126 under the in?uence of a spring 136. A supply 45 to be limited to the precise details set forth but desire
tank 132 containing hydraulic ?uid under pressure is pro
to avail myself of such changes and alterations as fall
vided with a conduit 134 which leads to a passage 136
within the purview of the following claims.
in the valve 116 communicating with the passage 126
I claim:
through a bore 138. The cylinders 168 are ?tlcd with
1. In a ram type press having a movable die pad and
hydraulic ?uid under pressure from the supply tank 132 50 a hydraulic cushion for said die pad comprising a cylinder
through conduit 134, passages 136 and 126, past check
and a piston reciprocable in said cylinder and react
valve 128, passage 124, and port 118 to conduit 116.
ing against said die pad, said piston being adapted to re
The passage 120 is closed by a pressure relief valve
sist movement of said die pad to its retracted position
140 which is engaged by a spring 142 con?ned between
during the working stroke of the press and to return said
the valve 141} and an adjusting screw 144. When the die 55 die pad to its extended position on the return stroke of
pad 104 is retracted, the pistons 106 are forced down~
the press, and a supply tank adapted to contain hy
wardly to dispace the hydraulic ?uid through the con
draulic ?uid under pressure; means for controlling the
duits 110 and 122 into passage 121i, and when the pres
?ow of hydraulic ?uid to and from said cylinder com
sure of the hydraulic ?uid exceeds a predetermined
prising a ?rst passage connecting said cylinder and tank
amount the pressure relief valve 140 will open, allowing 60 through which ?uid under pressure is supplied from
the ?uid to return to the tank 132 through passages 146
said tank to said cylinder and the piston therein to move
and 148 and conduit 150. The passage 146 provides a
said die pad to its extended position during the return
communication between the passage 12% and the passage
stroke of the press, a check valve in said ?rst passage
126 and is normally closed by a check valve 152 located
preventing ?uid ?ow therethrough from said cylinder
at one end of the bore 138. When the pressure in the 65 to said tank, a second passage connecting said cylinder
passages 146, 148 exceeds a predetermined amount dur
and tank through which ?uid is returned from said cyl
ing the working stroke of the press, the valve 152 will
inder to said tank during the working stroke of the
open to provide an additional passage for the return of
?uid to the tank, consisting of the passage 136 and con
press, a pressure relief valve in said second passage pro
viding resistance to the return of ?uid from said cylinder
duit 134, thus reducing the pressure and ?ow velocity 70 to said tank, a third passage connected into said ?rst
in the return lines to the tank. On the return stroke of
the ram, the valve 152 will open when the pressure
dilferential between the pressure at which the ?uid is
passage between said check valve and said tank and con
nected into said second passage between said pressure
relief valve and said tank, and a normally closed valve
maintained within the supply tank and the pressure in
in said third passage adapted to open to permit ?uid?ow
passage 126 exceeds a predetermined amount, thereby 75 from said second passage to said ?rst passage and back
3,027,151
5
6
to said tank thereby providing additional passage area
for the return of ?uid to said tank when the pressure
in said cylinder exceeds a predetermined pressure dur
ing the working stroke of the press, said normally closed
valve being adapted to open to permit ?uid ?ow from said
tank through said second passage into said ?rst passage
and to said cylinder thereby providing additional passage
into said ?rst passage when the pressure di?ferential be
tween said tank and cylinder exceeds a predetermined
amount during the return stroke of the press, and a time
delay valve in said ?rst passage operable responsive to the
?ow of ?uid through said second passage for closing said
?ow in parallel through portions of both said ?rst and
hydraulic cushion for said die pad comprising a cylinder
?rst passage to delay the re?lling of said cylinder through
said ?rst passage on the return stroke of the press.
area for the ?ow of ?uid to said cylinder when the pres
4. In a ram type press having a movable die pad and a
hydraulic cushion for said die pad comprising a cylinder
sure differential between said tank and cylinder exceeds
a predetermined amount during the return stroke of the 10 and a piston reciprocable in said cylinder and reacting
press.
against said die pad, said piston ‘being adapted to resist
2. In a ram type press having a movable die pad and a
movement of said die pad to its retracted position during
hydraulic cushion for said die pad comprising a cylinder
the working stroke of the press and to return said die
and a piston reciprocable in said cylinder and reacting
pad to its extended position on the return stroke of the
against said die pad, said piston being adapted to resist 15 press, and a supply tank adapted to contain hydraulic ?uid
movement of said die pad to its retracted position during
under pressure; means for controlling the ?ow of hydraulic
the working stroke of the press and to return said die
?uid to and from said cylinder comprising a ?rst passage
pad to its extended position on the return stroke of the
connecting said cylinder and tank, a check valve in said
press, and a supply tank adapted to contain hydraulic ?uid
?rst passage past which ?uid under pressure is supplied
under pressure; means for controlling the ?ow of hydraulic
from said tank to said cylinder and the piston therein to
?uid to and from said cylinder comprising a ?rst passage
move said die pad to its extended position during the re
connecting said cylinder ‘and tank through which ?uid
turn stroke of the press, a second passage connecting said
under pressure is supplied from said tank to said cylinder
cylinder and tank, a pressure relief valve in said second
and the piston therein to move said die pad to its extended
passage past which ?uid is returned from said cylinder to
position during the return stroke of the press, a check 25 said tank during the working stroke of the press, a third
valve in said ?rst passage preventing ?uid ?ow there
passage connected into said ?rst passage between said
through from said cylinder to said tank, a second passage
check valve and said tank and connected into said second
connecting said cylinder and tank through which ?uid is
passage between said pressure relief valve and said tank,
returned from said cylinder to said tank during the work
a normally closed valve in said third passage adapted to
ing stroke of the press, a normally closed pressure relief 30 open to provide additional passage area for the return
valve in said second passage providing the sole resistance
of ?uid to said tank when the pressure in said second pas
sage exceeds a predetermined pressure during the working
in said second passage to the return of ?uid from said
cylinder to said tank, a third passage connected into said
stroke of the press, and a time delay valve in said ?rst
?rst passage between said check valve and said tank and
passage operable for closing said ?rst passage to delay the
connected into said second passage between said pressure 35 re?lling of said cylinder through said ?rst passage on the
return stroke of the press.
relief valve and said tank, and a normally closed check
valve in said third passage adapted to open to permit ?uid
5. 1In a ram type press having a movable die pad and a
second passages back to said tank when the pressure in
and a piston reciprocable in said cylinder and reacting
said second passage exceeds a predetermined pressure dur 4.0 against said die pad, said piston being adapted to resist
ing the working stroke of the press and to permit ?uid
?ow from said tank in parallel through said portions of
movement of said die pad to its retracted position during
the working stroke of the press and to return said die
both said ?rst and second passages to said cylinder when
pad to its extended position on the return stroke of the
press, and a supply tank adapted to contain hydraulic ?uid
the pressure differential between said tank and cylinder
exceeds a predetermined amount during the return stroke 45 under pressure; means for controlling the ?ow of hydraulic
?uid to and from said cylinder comprising a ?rst passage
of the press, each of said portions of said ?rst and second
passages communicating directly with said tank and being
connecting said cylinder and tank, a check valve in said
unobstructed whereby hydraulic ?uid is free to ?ow in
?rst passage past which r?uid under pressure is supplied
either direction in said portions relative to said tank.
from said tank to said cylinder and the piston therein to
move said die pad to its extended position during the re
3. In a ram type press having a movable die pad and a
hydraulic cushion for said die pad comprising a cylinder
turn stroke of the press, a second passage connecting said
and a piston reciprocable in said cylinder and reacting
cylinder and tank, a pressure relief valve in said second
passage past which ?uid is returned from said cylinder to
against said die pad, said piston being adapted to resist
said tank during the working stroke of the press, a third
movement of said die pad to its retracted position during
the working stroke of the press and to return said die 55 passage connected into said ?rst passage between said
pad to its extended position on the return stroke of the
check valve and said tank and connected into said second
press, and a supply tank adapted to contain hydraulic ?uid
passage between said pressure relief valve and said tank,
under pressure; means for controlling the ?ow of hydraulic
a normally closed valve in said third passage adapted to
?uid to and from said cylinder comprising a ?rst passage
open to provide additional passage area for the ?ow of connecting said cylinder and tank, a check valve in said 60 ?uid from said tank into said ?rst passage when the pres
sure differential between said tank and cylinder exceeds a
?rst passage past which ?uid under pressure is supplied
predetermined amount during the return stroke of the
from said tank to said cylinder and the piston therein to
press, and a time delay valve operable for closing said
move said die pad to its extended position during the re
?rst passage to delay the re?lling of said cylinder through
turn stroke of the press, a second passage connecting said
cylinder and tank, a pressure relief valve in said second 65 said ?rst passage on the return stroke of the press.
6. In a ram type press having a movable die pad and a
passage past which ?uid is returned from said cylinder to
hydraulic cushion for said die pad comprising a cylinder
said tank during the working stroke of the press, a third
and a piston reciprocable in said cylinder and reacting
passage connected into said ?rst passage between said
against said die pad, said piston being ‘adapted to resist
check valve and said tank and connected into said second
movement of said die pad to its retracted position during
passage between said pressure relief valve and said tank,
the working stroke of the press and to return said die pad
a normally closed valve in said third passage adapted to
to its extended position on the return stroke of the press,
open to provide additional passage area for the return of
?uid to said tank when the pressure in said second passage
and a supply tank adapted to contain hydraulic ?uid
exceeds a predetermined pressure during the working
under pressure; means for controlling the ?ow of hydraulic
stroke of the press and for the ?ow of ?uid from said tank 75 ?uid to and from said cylinder comprising a ?rst conduit
3,027,151
7
8
interconnecting said tank and cylinder and having only av
single check valve therein past which hydraulic fluid is
supplied from said tank to said cylinder under tank pres
?uid in said one conduit exceeds a given pressure, said
valve controlled by-pass means being disposed relative to
said ?rst and second conduits so as to be effective for by
passing ?uid on both the ?uid supply and return cycles
cylinder and having a normally closed pressure relief valve 5 of said system.
therein forming the sole resistance in such second passage
References Cited in the ?le of this patent
to the return of ?uid from said cylinder to said tank dur
ing the working stroke of the press, valve controlled by
UNITED STATES PATENTS
sure, a second conduit interconnecting said tank and
pass means interconnecting said conduits on the tank side
of the said valves thereinwhereby to by-pass ?uid from 10
2,842,357
one conduit to the other conduit when the pressure of the
2, 890,669
Williamson ____________ __ July '8, 195 8
Williamson ____,_‘ ______ __ June 16, 1959
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