Improvements in Hydraulic Presses.
Year: 1897

page_text: Date of Application, 13th July, 1897
Complete Specification Left, 31st Mar., 1898--Accepted, 14th May, 1898
Improvements in Hydraulic Presses.
I, FRANK MCDOWELL LEAVITT, of Number 17 Adams Street, Brooklyn, in the
County of Kings and State of New York, United States of America, Mechanical
Engineer, do hereby declare the nature of the said invention to be as follows:-
This invention relates particularly to hydraulic drawing presses, although in
part applicable to hydraulic presses generally.
<<
In drawing presses for drawing metal sheets or plates into cupped form, the metal
sheet or blank is first gripped between annular clamps called a "blank holder,"
which tightly hold the marginal portion of the blank, while a plunger die or
punch moves from one side against the metal blank and forces it into a hollow
die on the other side, thereby "drawing" the sheet metal from its flat or shallow
form to the depth of the die, in which operation the marginal portion of the blank
is partly drawn or pulled through between the opposite clamping members of the
blank holder. For making deep articles, as sheet metal kettles half barrels, etc.,
the drawing operation is repeated two or more times, the blank being drawn each
time to a greater depth. For small or light work, power drawing presses are
commonly constructed with the blank holder and punch to be driven by means of
cams or cranks, with sometimes the interposition of toggles; but for heavy work
it is desirable to use a hydraulic drawing press. Hydraulic presses have been success-
fully used for such exceptionally heavy work as the dishing of boiler plates, one
hydraulic ram being employed to operate the blank holder, and another one to
drive the punch, but such machines being not designed for rapid or continuous
work, have been controlled solely by means of hand-operated valves, and their
operation is necessarily very slow. Attempts have been made to construct hydrau-
lic drawing presses adapted for rapid work less heavy than that of boiler plates,
but still beyond the proper capacity of ordinary power drawing presses; but in
such presses the difficulty has been encountered that the blank holder being pressed
up hydraulically, is liable to back off under the severe strain which occurs while
the punch is acting on the metal, thereby permitting the metal to pucker or buckle
in drawing through the blank holder.
It is essential to successful drawing that the blank holder shall be practically
unyielding, so that when it is closed upon the metal sheet, its members cannot
move apart, but must maintain a space between them no greater than that of the
thickness of the metal, while yet gripping the metal not too tightly to permit it to
draw through the blank holder as it is distended by the punch. If the blank holder
grips the blank too tightly to permit it to feed through, the metal will tear apart
under the stress of the punch; and if the blank holder yields and opens partially,
it will permit the metal to buckle or pucker, instead of being drawn flat.
My invention aims to provide a hydraulic drawing press which shall conform to
these conditions, and which moreover shall be capable of rapid operation, and which
to this end is made automatic in its movements, requiring only to be started by the
operator after he has placed the blank in position, whereupon it will execute one
entire series of movements required to complete one drawing operation, and will

page_text: then come to rest until the work shall have been removed and another blank put in
place, and the press again started. My invention comprises certain interacting
hydraulic and mechanical connections, and also a novel construction of pump
adapted to supply the liquid under pressure for operating the press, and novel means
of control or distribution in connection therewith.
According to my invention I operate the blank holder or platen not directly.
from a hydraulic ram as heretofore, but indirectly through the medium of one or
more pairs of toggles so arranged that the blank holder is seated upon the toggles,
and when gripping the work the toggles are straightened, and the reaction of the
blank holder cannot be transmitted to the hydraulic ram to force it back, thereby
admitting of the utmost nicety in the mechanical adjustment of the extent of
closure of the blank holder, while utilizing fully the great power of a hydraulic
cylinder and ram for operating the blank holder. The punch is operated by direct
connection with another hydraulic ram. The opposite ends of the cylinders of the
two rams are connected by suitable passages with a controlling valve or distributor
so constructed that in one position the press is held at rest; in a second position
fluid pressure is admitted to the passage communicating with the blank holder
ram, while the other passage thereof is opened of the exhaust, thereby moving the
blank holder ram to close the blank holder upon the sheet metal blank; in a third
position communication with the blank holder ram is cut off and fluid pressure is
admitted to one side of the punch ram to cause the punch to advance and draw the
sheet metal into the die; in a fourth position fluid pressure is admitted to one of
the rams to retract it, and the opposite or eduction side of the cylinder of this ram
is connected through the valve to the induction passage of the other ram, whereby
the two rams are hydraulically coupled together serially or in tandem, so that they
move simultaneously, the eduction passage from the second ram being opened to the
exhaust; and upon the completion of this retracting movement of the rams (which
retires the punch and opens the blank holder to release the work) the valve is
restored to its first position, thereby holding the press at rest. The press is caused
to automatically execute the prescribed succession of movements by means of
mechanical devices, such as tappets, with power-driven mechanism whereby at the
completion of each movement the valve is thrown to the 'next position, until the
end of the operation, whereupon the automatic control ceases, and the press remains
motionless until again started. The tappets may be constructed so as to bo
independently adjustable to vary the stroke of the respective rams. By preference
I subdivide the controlling valve into two valves one of which may be called the
distributor controlling the passages leading to the hydraulic cylinder, and the other
the stop valve, controlling the passage to the distributor, the said stop valve being
movable independently in order to stop the operation at any time, or by a partial
movement to control the speed. For operating these valves, I employ a clutch-
controlled shaft or rotary part movable a fraction of a revolution at each clutch
engagement, and a tappet mechanism for engaging the clutch at the end of each
of the series of movements performed by the press. As the source of hydraulic
pressure, I provide a constantly driven duplex pump operating at high speed and
having positively driven valves, and the current from which is either directed by
the stop valve to the distributing valve and thence into the hydraulic cylinders, or
when the press is not operating it is directed by the stop valve freely back into the
reservoir from which the pump draws, thereby relieving the pump of resistance,
and requiring no useless expenditure of power while the press is inactive.
In the case of a hydraulic press having its cylinder and ram so arranged that the
ram tends to move by gravity in one direction, and having a distributor for
controlling the flow to said cylinder, a valve may be arranged to oppose the outflow
of liquid from said cylinder during the gravitating movement of the ram, whereby
it serves to moderate said movement.
The pump is preferably constructed with duplex pistons, the one having a lead of
approximately 90 degrees in advance of the other, and the valve for each piston
being positively driven by mechanical connection with the other.
The pump is

page_text: also preferably arranged within and enclosed by the reservoir of liquid from which
the pump draws. In the case of oil being used to operate the various rams, the
oil reservoir is arranged to enclose the pump and its driving mechanism whereby
their lubrication is assured, suitable means being provided for lubricating the
driving shaft of the pump.
The pump, stop valve and distributor may be arranged within the oil reservoir
with the object of causing the discharge from said valves and all leakage to be
received in said reservoir.
Dated this 19th dow of Tulu 1807
Improvements in Hydraulic Presses.
I, FRANK MCDOWELL LEAVITT, of Number 17 Adams Street, Brooklyn, in the
County of Kings and State of New York, United States of America, Mechanical
Engineer, do hereby declare the nature of the said invention and in what manner
the same is to be performed, to be particularly described and ascertained in and
by the following statement:-
-
This invention relates particularly to hydraulic drawing presses, although in
part applicable to hydraulic presses generally.
66
65
In drawing presses for drawing metal sheets or plates into cupped form, the metal
sheet or blank is first gripped between annular clamps called a blank holder,"
which tightly hold the marginal portion of the blank, while a plunger die or
punch moves from one side against the metal blank and forces it into a hollow
die on the other side, thereby "drawing" the sheet metal from its flat or shallow
form to the depth of the die, in which operation the marginal portion of the blank
is partly drawn or pulled through between the opposite clamping members of the
blank holder. For making deep articles, as sheet metal kettles, half barrels, etc.,
the drawing operation is repeated two or more times, the blank being drawn each
time to a greater depth. For small or light work, power drawing presses are
commonly constructed with the blank holder and punch to be driven by means of
cam or cranks, with sometimes the interposition of toggles; but for heavy work,
it is desirable to use a hydraulic drawing press. Hydraulic presses have been success-
fully used for such exceptionally heavy work as the dishing of boiler plates, one
hydraulic ram being employed to operate the blank holder, and another one to
drive the punch, but such machines being not designed for rapid or continuous
work, have been controlled solely by means of hand-operated valves, and their
operation is necessarily very slow. Attempts have been made to construct hydrau-
lic drawing presses adapted for rapid work less heavy than that of boiler plates,
but still beyond the proper capacity of ordinary power drawing presses; but in
such presses the difficulty has been encountered that the blank holder being pressed
up hydraulically, is liable to back off under the severe strain which occurs while
the punch is acting on the metal, thereby permitting the metal to pucker or buckle
in drawing through the blank holder.
It is essential to successful drawing that the blank holder shall be practically.
unyielding, so that when it is closed upon the metal sheet, its members cannot
move apart, but must maintain a space between them no greater than that of the
thickness of the metal, while yet gripping the metal not too tightly to permit it to
draw through the blank holder as it is distended by the punch. If the blank holder
grips the blank too tightly to permit it to feed through, the metal will tear apart

page_text: under the stress of the punch; and if the blank holder yields and opens partially,
it will permit the metal to buckle or pucker, instead of being drawn flat.
My invention aims to provide a hydraulic drawing press which shall conform to
these conditions, and which moreover shall be capable of rapid operation, and which
to this end is made automatic in its movements, requiring only to be started by the
operator after he has placed the blank in position, whereupon it will execute one
entire series of movements required to complete one drawing operation, and will
then come to rest until the work shall have been removed and another blank put in
place, and the press again started. My invention comprises certain interacting
hydraulic and mechanical connections, and also a novel construction of pump
adapted to supply the liquid under pressure for operating the press, and novel means
of control or distribution in connection therewith.
According to my invention I operate the blank holder or platen not directly
from a hydraulic ram as heretofore, but indirectly through the medium of one or
more pairs of toggles so arranged that the blank holder is seated upon the toggles,
and when gripping the work the toggles are straightened, and the reaction of the
blank holder cannot be transmitted to the hydraulic ram to force it back, thereby
admitting of the utmost nicety in the mechanical adjustment of the extent of
closure of the blank holder, while utilizing fully the great power of a hydraulic
cylinder and ram for operating the blank holder. The punch is operated by direct
connection with another hydraulic ram. The opposite ends of the cylinders of the
two rams are connected by suitable passages with a controlling valve or distributor
so constructed that in one position the press is held at rest; in a second position
fluid pressure is admitted to the passage communicating with the blank holder
ram, while the other passage thereof is opened to the exhaust, thereby moving the
blank holder ram to close the blank holder upon the sheet metal blank; in a third
position communication with the blank holder ram is cut off and fluid pressure is
admitted to one side of the punch ram to cause the punch to advance and draw the
sheet metal into the die; in a fourth position fluid pressure is admitted to one of
the rams to retract it, and the opposite or eduction side of the cylinder of this ram
is connected through the valve to the induction passage of the other ram, whereby
the two rams are hydraulically coupled together serially or in tandem, so that they
move simultaneously, the eduction passage from the second ram being opened to the
exhaust; and upon the completion of this retracting movement of the rams (which
retires the punch and opens the blank holder to release the work) the valve is
restored to its first position, thereby holding the press at rest. The press is caused
to automatically execute the prescribed succession of movements by means of
mechanical devices, such as tappets with power-driven mechanism, whereby at the
completion of each movement the valve is thrown to the next position, until the
end of the operation, whereupon the automatic control ceases, and the press remains
motionless until again started. The tappets may be constructed so as to be
independently adjustable to vary the stroke of the respective rams. By preference
I subdivide the controlling valve into two valves, one of which may be called the
distributer controlling the passages leading to the hydraulic cylinder, and the other
the stop valve, controlling the passage to the distributor, the said stop valve being
movable independently in order to stop the operation at any time, or by a partial
movement to control the speed. For operating these valves, I employ a clutch-
controlled shaft or rotary part movable a fraction of a revolution at each clutch
engagement, and a tappet mechanism for engaging the clutch at the end of each
of the series of movements performed by the press. As the source of hydraulic
pressure, I provide a constantly driven duplex pump operating at high speed and
having positively driven valves, and the current from which is either directed by
the stop valve to the distributing valve and thence into the hydraulic cylinders, or
when the press is not operating it is directed by the stop valve freely back into the
reservoir from which the pump draws, thereby relieving the pump of resistance,
and requiring no useless expenditure of power while the press is inactive.
In the case of a hydraulic press having its cylinder and ram se arranged that the

page_text: ram tends to move by gravity in one direction, and having a distributer for
controlling the flow to said cylinder, a valve may be arranged to oppose the outflow
of liquid from said cylinder during the gravitating movement of the ram, whereby
it serves to moderate said movement. The pump is preferably constructed with
duplex pistons, the one having a lead of approximately 90 degrees in advance of
the other, and the valve for each piston being positively driven by mechanical
connection with the other. The pump is also preferably arranged within and
enclosed by the reservoir of liquid from which the pump draws.
In the case of
oil being used to operate the various rams, the oil reservoir is arranged to enclose
the pump and its driving mechanism whereby their lubrication is assured, suitable
means being provided for lubricating the driving shaft of the pump.
The pump stop valve and distributer may be arranged within the oil reservoir
with the object of causing the discharge from said valves and all leakage to be
received in said reservoir.
I have shown in the accompanying drawings the preferred construction of
hydraulic drawing press in which my invention is embodied.
Fig. 1 is a front elevation of the machine partly in section;
Fig. 2 is an end elevation partly in section on the line 2-2 in Fig. 1, showing
the blank holder open;
Fig. 3 is a similar sectional end elevation, but showing the blank holder closed;
Fig. 4 is a horizontal section of the pump chamber or reservoir on the line 4-4
in Fig. 5, and showing the pump in plan;
Fig. 5 is a vertical section thereof on the line 5-5 in Fig. 4;
Fig. 6 is a vertical section through the pump in the plane of the line 6-6
in Fig. 4;
Fig. 7 is a transverse section on the line 7-7 in Figs. 4 and 5 ;
Fig. 8 is a transverse section on the line 8-8 in Figs. 4 and 5;
Fig. 9 is a fragmentary vertical section in the plane of the line 9--9 in Fig. 4;
Fig. 10 is a partial mid-sectional elevation looking from the rear opposite
to Fig. 1, and showing the pump and controlling valves diagrammatically to
disclose the connections between the latter and the hydraulic cylinders;
Figs. 11, 12 and 13 are sections showing the valves in their three positions other
than that shown in Fig. 10;
Fig. 14 is a diagrammatic view showing the mechanical connections for
controlling the movements of the valves;
Fig. 15 is a detail of the valve operating clutch, and Fig. 16 is a transverse section
thereof;
Figs. 17, 18 and 19 are diagrammatic views showing the press in operation and
illustrating respectively the three successive operative movements;
Fig. 20 is a plan partly in horizontal section showing the mechanism through
which the tappet movements are communicated to the clutch;
Referring to the drawings, let a designate the punch or male die, 6 the female
die, and c the blank or metal sheet to be operated upon. The blank holder d
comprises two members, one of which is conveniently constructed as the margin
of the die b, and the other as a ring e. Either of these members may be stationary
and the other movable, or it is even possible that both might be movable. In the
construction shown the ring e is the stationary member while the die bis movable.
The blank holding ring e is mounted on a cross piece or bed B rigidly fixed to the
main frame A of the press. The die b or movable member of the blank holder is
mounted on a cross head or platen C, which is mounted to move vertically, being
guided by ways 21 on the main frame A. The punch a is mounted directly upon a
hydraulic ram or plunger D having a head or piston 22, and moving in a hydraulic
cylinder E, which may as shown be connected to the bed B by pillars or tie rods 23.
The platen C is mechanically connected to and operated by a hydraulic plunger
or ram F, having an enlarged head or piston 24, and working in a cylinder G,
which is shown as fastened upon the outer side of the main press frame A.
The connection between the platen C and the ram F is made through the medium

page_text: of toggles, as essentially shown in Figs. 17, 18 and 19, and which in practice are
preferably arranged and constructed as shown in Figs. 1, 2, 3 and 10. The
platen C is connected by upright rods f f to two cross heads CC beneath, to the
ends of which are jointed the links g g of two pairs of toggles H H, the other toggle
of each pair being a toggle arm projecting from a rock shaft I. The rock
shafts II extend across the front and rear of the frame, have bearings in the
uprights thereof, and on one end of each is fixed a crank arm i, these two crank
arms being connected in any suitable manner to the ram F, preferably by links j j
interposed between the arms and the cross head which is fixed on the lower end of
the ram.
In Figs. 17, 18 and 19, in order to make the relations more clear, the
die dis shown as carried underneath the cross head C¹, which thus constitutes the
platen. When the ram F is down, the die is raised as shown in Fig. 17, and when
the ram rises, the die is lowered by the straightening of the toggles H H, as shown
in Fig. 18. In the latter position the toggles H H transmit the entire strain from
the blank holder to the shafts I I, and hence to the main frame A, so that the
blank holder is held rigidly closed by the entire strength of the frame; and the
thrust tending to open the blank holder, being transmitted in the line of the toggles,
has no tendency to turn the shafts I I, and hence cannot be transmitted to the ram F.
If this thrust were transmitted directly to the ram F, there would be liability that
this ram would yield to the thrust to the extent that leakage can occur around its
piston head and stuffing box, as well as in the controlling valve. Hence by this
simple intermediation of the toggles between the ram and platen, I avoid this serious
disadvantage heretofore inherent in hydraulic drawing presses. In the construction
shown in Figs. 1, 2 and 3, where the platen C is mounted above the cross heads C¹
on rods ff, the press is made very compact, and at the same time means is provided
for adjusting the blank holder, the rods being screw-threaded, and the piston being
confined thereon between adjusting nuts 25, 25, by which the platen may be raised
or lowered to bring the blank holder to the desired adjustment.
The liquid for operating the hydraulic rams is pumped by a pump P through
the controlling valve or valves, the latter comprising a stop valve J and a distribut-
ing valve K (Fig. 10), and from the latter lead the pipes or passages which
communicate with the opposite ends of the respective cylinders E and G.
pump and valves are enclosed in a casing or tank L, which constitutes the reservoir
for holding the oil or other liquid employed for the hydraulic operation.
The
The construction of the stop-valve and distributer may be widely varied, and if
desired the functions of both may be combined in one valve. The stop valve J
receives the stream of liquid from the pump, and either directs it to the distributer
valve, or permits' it to escape freely into the reservoir L; or in an intermediate
position it may admit a more or less reduced stream to the distributer, correspond-
The
ingly choking the escape or short-circuiting of the oil to the reservoir.
distributer valve directs the stream of oil into either end of either hydraulic cylinder,
and by its movement to different positions, determines the direction of flow of the
liquid, and hence controls the movements of the press. In the construction shown,
both valves are operated by a shaft M above, which shaft has a crank for operating
The exact arrange-
the distributer K, and a cam 26 for working the stop valve J.
ment of the shaft M is shown in Figs. 5 and 7. The liquid from the pump flows
through a port or passage 27 to the valve J, which has a piston 28, which when
above said port as in Fig. 10, directs the liquid through a port 29 to the distributor
valve, or when lowered as in Fig. 11, permits the free escape of the liquid, as shown
by arrows in that figure. Hence the valve J may be any valve which by move-
ment to two opposite positions accomplishes these respective results; but preferably
it is made with two pistons moving in a cylinder with which the ports communicate,
the stems carrying the pistons being provided with a roller which is acted on by the
cam 26, and is pressed up by a spring 30 (Fig. 5).
The distributer K is constructed preferably as a cylinder having four ports at
different levels, and two pistons 31 and 32 separated sufficiently to bridge two ports,
and each having sufficient width of face to cover one port, a stem being extended

page_text: upward and engaging the crank on the shaft M. Of the four ports, the upper and
lower ones are connected respectively to the upper and lower ends of the cylinder G,
and the two middle ones are connected to the opposite ends of the cylinder E. The
distributer K is movable to three positions corresponding to the upstroke, down-
stroke and midstroke of the crank, the upstroke position being shown in Fig. 13,
the downstroke in Fig. 10, and the midstroke in Figs. 11 and 12, the valve K
occupying the same position in both the latter figures, but the cam 26 by being
upturned in one and downturned in the other, closes the valve J to the distributer
in Fig. 12, and opens it to the reservoir to short-circuit the fluid in Fig. 11.
The
Hence for operating the valves the shaft M is turned successively to four different
positions 90 degrees apart. To accomplish this I preferably provide a continuously
driven pulley turning loosely on this shaft and driven by a belt 33 (Fig. 1),
with a clutch mechanism for coupling the shaft to the pulley during a quarter
revolution, and then uncoupling it and leaving it stationary until again coupled, so
that the shaft is driven a quarter revolution each time the clutch is operated.
clutch may be variously constructed, but a simple and suitable form is that shown
in Figs. 14, 15 and 16, where the pulley M¹ turns freely on a sleeve or hub fixed on
the shaft, having preferably flanges 34, Fig. 16, (not shown in Figs. 14 and 15),
in which is journalled a spindle 35, which is half cut away as shown in section
in Fig. 15, so that when the clutch is disengaged, no portion of this spindle
protrudes into contact with the hub of the pulley M¹, this being the position of rest
shown in Fig. 14, where an arm 36 fixed on the end of the spindle is held by a dog k.
But as soon as this dog k is moved out of the way, as shown in Fig. 15, the arm 36
is thrown outward by a spring 37 thereby causing the spindle 35 to rotate into.
engagement with a notch 38 (three being shown) in the pulley hub, so that the
pulley and shaft are temporarily locked together, and the shaft revolves with the
pulley until the arm. 36 is pushed back by the next dog 2, which is 90 degrees
removed from the first, whereby the clutch is disconnected, and the shaft M being
no longer driven, stops. There are four dogs k, 2, 3, and k, as shown in Fig. 14,
so that this operation is repeated each time one of these dogs is displaced to permit
the clutch to engage.
The clutch described is a well known clutch commonly
employed for imparting one revolution at a time..
The clutch is operated by tappet mechanism shown most clearly in the
diagram Fig. 14. The description of this mechanism will be given in connection
with the operation which will now be described.
k
Figs. 14 and 11 show the machine in the position of rest. The liquid delivered
from the pump through passage 27, is cut off from the distributer by the piston 28
of stop valve J, and flows freely out at the top of this valve, falling back into the
The pulley M¹
mass of oil in the reservoir, so that the pump works without load.
revolves without turning the valve shaft M, since the clutch is disconnected, the
dog holding the clutch arm 36 pressed in. This dog is connected by a link 39
to a treadle lever 40, which is pressed up by a spring 41 (Fig. 14) which is stronger
than clutch spring 37. The parts will remain in this position until the operator,
having adjusted the blank c upon the blank holder ring e, as shown in Fig. 17,
depresses the treadle 40, and thereby releases the restraining dog k, whereupon the
clutch engages, and the shaft M is driven by the revolving pulley during one
quarter of a revolution, until the clutch arm is disengaged by the dog 2, which has
This movement carries the stop
a spring 42 stronger than the clutch spring.
valve J up to the position shown in Figs. 10 and 17, so that the flow is directed
from port 27 into port 29 leading to the distributer K; and the latter is raised to
the position shown in the same figures, so that port 29 is put into communication
with the two lower passages 43 and 44, the upper passage 45 is exposed above the
upper valve piston 31, and the port 46 is closed by this piston.
passages 29 and 43 are in constant communication, being extended annularly around
the valve chamber; it hence results that whenever the fluid pressure is admitted
to the distributer, it is transmitted through passage 43 to the upper side of hydraulic
cylinder E, and presses the ram D downwardly. As the ram D is already at the
•
The

page_text: bottom of its stroke, this pressure simply holds it down, since the passage 46 is
closed, so that no pressure can reach the underside of this ram. The flow accordingly
takes place from passage 29 through distributer K to passage 44, to the under side
of ram F, which moves upward as shown in Fig. 17, thereby lowering the blank
holder d, until upon the straightening of the toggles the blank holder closes upon
and grips the blank, the end of this movement being shown in Fig. 10.
The liquid
expelled from cylinder G by this movement, flows out through passage 45 to the
valve chamber of distributer K, from which it escapes by lifting a valve 47,
which is pressed down by a spring 48. This valve is employed to moderate the
movement, since the weight of the blank holder platen C and other descending parts,
is considerably greater than that of the ram F and other ascending parts, so that
to prevent a rapid falling movement of the platen, it is necessary either to counter-
balance it, or to interpose a resistance to the outflow of fluid from the cylinder G;
and by preference I have chosen the latter means, the spring 48 being given
sufficient tension to overcome the preponderating weight of the descending parts,
and thereby require that some force be exerted through the ram F in order to press
down the platen. Any arrangement of choking or throttling valve in connection
with the eduction passage 45, will answer this purpose.
At the end of this first movement, the dog is automatically displaced in order to
re-engage the clutch and cause the shaft M to make another quarter turn. This may
be done by the means shown in Fig. 14, where the ran F is connected by a link 49
to a lever 50 having a tappet arm 51, which as the ram reaches the end of its stroke
strikes a lever 52, and through a link 53 communicates its movement to the dog k².
The clutch then carries the shaft M a quarter turn until it is disengaged by the
next dog k³. This brings the valves to the third position shown in Figs. 12 and 18.
The valve J is not moved, but the valve K is restored to its first position, where its
pistons close both passages 44 and 45 leading to the ram 1, thus holding this ram
immovable, and consequently retaining the blank holder stationary. The two
intervening passages 43 and 46 are put in communication, so that the hydraulic
pressure is admitted to both ends of the cylinder E, and by reason of the area of the
under side of the ram head or piston being considerably greater than that on its
upper side, the ram is forced upward, the flow taking place from passage 29 to
distributer K, to passage 46, thence beneath the ram forcing it up and expelling
the liquid from its upper side, through passage 43 back to the distributer K, where
it commingles with the liquid flowing into passage 46, so that more liquid flows
into the cylinder E than flows out of it, to the extent of the difference in capacity
on opposite sides of the ram or piston; or in other words, the upward pressure
corresponds to the cross area of the neck of the ram D. As the ram D carries the
punch a, this upward movement causes the punch to draw the metal into the die b;
at the end of this movement the clutch is again engaged to give the shaft M another
quarter turn to this end the pawl is retracted by any convenient mechanism,
preferably by that best shown in Fig. 14, where the ram D carries a cross head 54,
which connects by a link 55 to a lever 56 fixed on a shaft 57, to which also is fixed
the other lever arm 58, which is connected by a link 59 to a sliding sleeve 60
sliding freely upon a vertically movable rod 61, on which is set a tappet or collar 62.
The weight of the rod 61 ordinarily rests on a counterweighted lever 63, which is
fixed on a shaft 64, the other arm 65 of which is in practice connected by a single
link 66 (Fig. 1) to the dog 3 (but to make the connection clear in Fig. 14, I have
there shown it as connecting through link 67, elbow-lever 68, link 69, elbow-lever 70,
and thence by link 66 to the dog). As the ram D rises, it pushes up the slide 60
until the latter strikes the tappet 62 and raises the rod 61, thereby lifting its weight
off the counterweighted lever 63, the weight of which is less than that of the rod,
but which is sufficient to move the dog 3 and release the clutch.
The shaft M then makes another quarter turn to the fourth position shown
in Figs. 13.and 19, where the clutch is disengaged by the dog kª. This movement
does not affect the valve J, but carries the valve K to its uppermost position, where
its pistons connect the two upper ports 45 and 46, while opening the lower port 44

page_text: to the discharge. The liquid now flows as shown in Fig. 19 from passage 29 by
passage 43 to the upper end of cylinder E, thereby pressing down the ram D, while
the liquid beneath it is expelled through passage 46 to the distributer, which
connects it with passage 45, and thence to the upper end of cylinder G, which it
forces downward, while the liquid from beneath its piston head flows out through
passage 44 to the distributer and wastes freely into the reservoir. This movement
causes both rams to simultaneously descend, thereby lowering the punch a and
raising the platen C carrying the blank holder d and die b. The ascent of the die
carries the blank c up frictionally with it until the latter is expelled by a
"knock-
out" 71, consisting of a disk mounted on a stem 72 which is fixed to the cross
head 73 of the main frame of the press, being vertically adjustable by any suitable
means, preferably by being screwthreaded and clamped by adjusting nuts 74, 74,
as shown in Fig. 1.
At the end of this third movement, the clutch is again engaged to turn the
shaft M another quarter revolution, and thereby restore the valves to the first
position. This is done by retracting the dog through the medium of any suitable
tappet mechanism, preferably that shown best in Fig. 14. The ram F is connected
by link 49 to lever 50 already referred to, the opposite arm of which connects by a
link 75 to a sleeve 76, which slides freely on an upright rod 77, on which is fixed
an adjustable tappet or set collar 78; the lower end of the rod rests upon a counter-
weighted lever 79, which is fixed on a shaft 80, to which is fixed another arm 81,
which in practice connects by a link 82 directly to the dog as shown in Fig. 1
(but to more clearly show the parts in Fig. 14, the link 82 is there shown as
As the ram F
connecting through an elbow-lever 83 and link 84 with the dog).
descends in the third movement just described, it slides the sleeve 76 upward on the
rod 77 until the sleeve strikes the tappet 78 and lifts the rod, thereby taking its
weight off from the lever 79, the counterweight of which is not heavy enough to lift
the rod 77, but is heavy enough to communicate motion through the intervening
parts to draw back the dog k The clutch then engages and carries the shaft Ma
final quarter turn, bringing it again to the first position, where it is shown
in Fig. 14, and where it is again arrested by the first dog k. By this movement the
valves are again dropped to the position shown in Figs. 14 and 11, the valve J being
thus moved down until it cuts off communication between the pump and the
passage 29 leading to the distributer, and permits the liquid from the pump to flow
out through the top of the valve chamber and waste freely back into the reservoir.
It is apparent from the foregoing description that that part of my invention
which involves the automatic operation of the press, requires the alternation of
hydraulic and mechanical operations, the hydraulic operations effecting the move-
ment of the active parts of the press, namely, the blank holder and punch, and the
mechanical operations serving to shift the valves for controlling the successive
hydraulic operations. While the use of a constantly driven part such as a pulley
with a clutch for coupling it at intervals to the intermittently driven part (such as
the shaft M) by which the valves are shifted, is preferable, yet any other mechanical
arrangement adapted to shift the valves at intervals under the control of the
The mechanism
hydraulically driven parts of the press may be substituted.
involves essentially valves movable to four positions, namely, (1) the position of
rest; (2) the position which admits liquid to propel the ram which closes the blank
holder; (3) the position which admits liquid to propel the ram which carries the
punch or male die; and (4) the position which admits hydraulic pressure to both
cylinders for causing the simultaneous retraction of the rams operating both the
plunger and blank holder; followed by a return to the first position. Any valve
or combination of valves that is adapted for effecting the necessary hydraulic port
combinations for bringing about these three successive movements of the rams;
and any mechanical or other intermediary adapted at the end of each ram move-
ment to cause the shifting of the controlling valve or valves to the position for
I have referred to three
invention.
causing the next movement, will be within my
ram movements, the third movement consisting in the simultaneous retraction of

page_text: both rams, and this is preferable because of the saving of time as compared with
retracting the two rams by two separate movements, but my invention is not limited
to the simultaneous retraction of both rams.
The
The tappet mechanism shown is preferred, because of the facility of its adjustment
to various sizes of dies and varying lengths of stroke. The only ram movement
which is not subject to variation, is the upward movement of the ram F, which
should extend invariably to such point as will straighten the toggles H H.
downward movements of this ram should be variable in proportion to the variations
in depth of the die b, and the extent of its down stroke may be varied by
setting the tappet collar to varying heights on the rod 77. The same adjustment
controls also the downstroke of the ram 1), since during the return stroke the two
rams are hydraulically coupled together in tandem, so that at the end of a given
descent of the ram F, the tappet 78 is encountered and displaced, and the clutch-
dog is moved to engage the clutch and shift the valves, and thereby stop further
movement of the rams. The extent of upstroke of the ram D, which should vary
in proportion to the depth of the dies, is adjustable by setting the tappet 62 higher
or lower on the rod 61.
The special construction of pump by which the liquid is forced into the press
cylinders, is best shown in Figs. 4 to 8. The pump is a high speed, duplex, double-
acting pump, having positively-driven valves. Power is applied by a belt or
otherwise to a shaft 85 having two cranks set at 90 degrees apart, which through
pitmans 86 communicate movement to two levers or walking beams 87, which are
pivoted on a shaft 88. Each lever 87 connects on opposite sides of its axis with
pump pistons or plungers 89 and 90 respectively, the positions of which are indicated
by dotted circles in Fig. 4. The two plungers connected to one lever constitute
together a double-acting pump, and each such pump is controlled by a valve 91,
which is driven positively by connection with the lever 87 of the other pump, the
valve being connected by a link to a pin 92 projecting from such opposite lever.
By reason of the two levers being vibrated 90 degrees apart, each valve is stationary
in one extreme position, and the plungers the flow from which it controls, are at
midstroke and moving with greatest rapidity; and conversely as the plungers
reach either end stroke and stop, their valve is then at midstroke with the ports
closed, and is moving at maximum speed to reverse the ports preparatory to the
next opposite stroke of the plungers. The port connections are most clearly shown
in Fig. 6, where the valve is shown as though it were in the same plane with
the plungers. The suction pipe 93 from the oil reservoir opens directly into the
bottom of the valve chamber 94, from which a port 95 communicates with the
cylinder of plunger 89, while a similar port 96 communicates from the valve
chamber to the cylinder of plunger 90, and between these is an outflow port 97.
The valve in addition to an upper intercepting piston which answers as a stuffing
box, has two active pistons 98 and 99, the space between which is adapted to connect
either of the ports 95 or 96 with the outflow port 97; when the valve is lifted as
in Fig. 6, it uncovers port 95, so that it communicates with the suction pipe 93,
and when the valve is lowered as in Fig. 5, the liquid flows through the hollow of
the valve to above its piston 98, and thence enters the port 96. This valve con-
struction, however, is not new in itself and may be greatly varied.
This pump is
designed for operating at 200 revolutions per minute, and is adapted to work up to
a maximum pressure of 2,000 pounds per square inch, these figures being given only by
way of illustration, since other speeds and pressures are admissible. At this high speed
any ordinary leakage around the plungers and valves becomes inconsequential, and
a pump of small size and compact design becomes admissible in a hydraulic press
requiring for rapid operation a flow of large volume under heavy pressure. The
outflow ports 97 from the two valves 91 unite and merge into the passage 27 leading
to the valve J. The passage 97 also extends to a relief or safety valve 100, shown
in Fig. 5, consisting merely of a tappet valve pressed down by a spring with
sufficient pressure to resist any normal hydraulic pressure, and adapted to open in
case from any cause the pressure becomes so high as to involve danger of breakage.

page_text: The essentials of this pump are that it shall be double-acting and duplex, in order
to discharge a constant stream of uniform velocity, and by reason of its high speed,
that its valves (to avoid hammering) shall be positively driven, the valve for each
double-acting pump being driven from the other, and the two pumps being
coupled 90 degrees apart.
As already stated, the pump and controlling valves are all enclosed in the
casing L, which serves also as the reservoir for the liquid. This construction has
the advantage of enclosing all parts of the pump, and of ensuring their thorough
lubrication, since oil is used as the hydraulic liquid, and the motion of the pump is
accompanied by a sufficient spattering of the oil to keep all the working parts
thoroughly coated therewith.
For lubricating the bearings of the crank shaft 85,
I provide a funnel 101 (Fig. 9) arranged to catch the drops or spatterings of oil,
and having a tube to conduct them into a groove along the top of the bearing; any
oil passing through the bearing and which might escape on the exterior is arrested
by entering a circumferential groove 102 from the lower side of which a channel 103
leads back into the casing L to return the oil thereto.
I provide also means for graduating the flow in order to vary the speed of move-
ment of the rams. This might be done by separate means, but I preferably provide
As best shown
for this purpose a special construction of the stop valve J.
in Fig. 10, the port 27 where it opens into the valve chamber, is made wider than the
face of the piston 28, so that by lowering the valve J, a position may be reached in
which the piston 28 leaves the port 27 partly open on both sides, thereby permitting
a partial escape upwardly, and hence only a partial flow under pressure downwardly
through the port 29. By this means the pressure transmitted through the
distributer can be varied to a nicety, since the lower the valve is placed the more
nearly the flow of the distributer is cut off, and at the same time the more the
pressure is lowered by opening a free outflow above of greater area, and vice versa.
For thus adjusting the height of the valve J, I provide the means shown in Fig. 5,
consisting of a lever 104, one end of which is pivoted to the stem of the valve J,
and the other end of which engages a nut 105, which is adjusted up or down by a
screw stem 106. If for example it is desired to operate the press very slowly in
order to adjust the tappets, or for other reasons, the operator turns the stem 106
by its exterior hand wheel, and thereby presses down the valve J to practically the
bottom of its throw, and then, starting the press by pressing the treadle, he will
turn the stem 106 in the contrary direction so as to slowly elevate the valve J until
the press starts and moves with the speed required for his purpose; having completed
this adjustment, and desiring that the press shall travel at normal speed, he
continues to elevate the valve until the speed of the rams reaches any desired rate
up to the maximum, which is reached when the valve J is permitted to ascend to
the highest point which the cam 26 admits of.
It must not be inferred from the particularity of detail with which I have
described the exact construction shown, that my invention is limited to the details
thus set forth, since in fact my invention is susceptible of wide variations without
departing from its essential features.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what
I claim is:-
1. In a press having two hydraulic cylinders and rams and a controlling valve,
the arrangement whereby in one position of said valve the eduction side of one
cylinder is connected to the induction side of the other, so that the ram of the
former acts through the intervening hydraulic column to move the ram of the latter,
substantially as described.
2. In a drawing press two hydraulic cylinders and rams, the one for working
the blank holder and the other the punch, arranged in one position of the controlling
valve to connect the eduction side of one cylinder with the induction side of the

page_text: other to ensure simultaneous retracting movements of the punch and blank holder,
substantially as described.
3. In a drawing press having two hydraulic cylinders and rams, a continuously
driven pump, and a valve controlling the passages between the pump and cylinders
adapted to direct the liquid from the pump into either passage to drive either ram
in either direction, and to divert the liquid and return it freely to the pump when
the rams are to be held stationary, substantially as described.
4. In such a hydraulic press, the arrangement of a distributing valve controlling
the passages leading to the hydraulic cylinder, and a stop-valve controlling the
passage to the distributer in substantially the manner described.
5. In such a hydraulic press, the arrangement of a controlling valve for directing
the flow from a source of hydraulic pressure to the opposite ends of the cylinders,
with the described means for causing the press to execute a prescribed succession
of movements, comprising tappets operated by the respective rams, and a power
driven mechanism adapted as each tappet is operated to displace the controlling
valve from one position to the next, the said tappets being preferably independently
adjustable to vary the stroke of the respective rams, substantially as described.
6. The valve operating mechanism comprising a continuously driven part (as M¹),
a valve operating part (as the shaft M), and a clutch for coupling them together,
the operation of which is controlled by tappet mechanism operated by the rams,
substantially as hereinbefore described.
7. The said clutch constructed with a projecting arm as 36, and clutch operating
dogs as k 2, etc., in positions corresponding to the stopping positions of the valve
operating shaft M, combined with tappet mechanisms operated by the rams and
connected to operate the respective dogs, substantially as herein before described.
8. A hydraulic press having its cylinder and ram so arranged that the ram tends
to move by gravity in one direction, having a distributer for controlling the flow
to said cylinder, and a valve arranged to oppose the outflow of liquid from said
cylinder during the gravitating movement of the ram, whereby it serves to moderate
said movement, substantially as herein before described.
9. The combination of stop-valve J and distributer K, with means for operating
them comprising a shaft M having a crank connected to the distributer, and a cam
adapted in one position to displace the stop valve, and means for turning said shaft
one quarter revolution at each movement, substantially as set forth.
10. The means for controlling the speed of the press consisting of the stop
valve J interposed between the pump and the distributer, and an adjusting device
for adjusting the extent of its opening.
11. The arrangement of the pump P, stop-valve J and distributer K within the
oil reservoir L, whereby the discharge from said valves and all leakage is received
in said reservoir, substantially as described.
12. The described construction and arrangement of the double-acting high-speed
pump Phaving positively-driven valves and delivering a constant stream, in connec-
tion with the stop valve and distributing valve, for feeding the hydraulic cylinders,
substantially as set forth.
J. C. MEWBURN & ELLIS,
55 and 56, Chancery Lane, London, Chartered Patent Agents.