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Publication numberUS2269778 A
Publication typeGrant
Publication dateJan 13, 1942
Filing dateMar 3, 1939
Priority dateMar 3, 1939
Publication numberUS 2269778 A, US 2269778A, US-A-2269778, US2269778 A, US2269778A
InventorsWesley P Merrill
Original AssigneeOilgear Co
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Metal working press
US 2269778 A
Abstract  available in
Images(6)
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Claims  available in
Description  (OCR text may contain errors)

Jan. 13, 1942. V w. PQMERRILL 2,259,773

' METALWORKING PRESS Filed March 3, 1939 e Sheets-Sheet 1 26 INVENTOR.

METAL WORKING PRESS Jan. 13, 1942.

Filed March 3, 1939 Fig. 5. A5

\ 9 i PSI 6 Sheets-Sheet 3 INVENTOR.

G P 2/ 4 I Jan. 13, 1942. w. P. MERRILL 2,269,778

METAL WORKING 'PRESS Filed March 3, 1939 6 Sheets-Sheet 4 INVENTOR.

Jan. 13, 1942. w. P. MERRILL 2,269,778

METAL WORKING PRESS 9 INVENTOR.

Patented Jan. 13, 1942 METAL WORKING PRESS Wesley P. 'Merrill, Milwaukee, Wis., assignor to The Oilgear Company, Milwaukee, Wis, a corporation of Wisconsin Application March 3, 1939, Serial No. 259,553

20 Claims.

This invention relates to metal working presses of the type having a ram which advances and retracts a movable die toward and from a stationary die to enable the dies to form metal into a desired shape, a pressure pad which supports the metal in position to be operated upon by the dies and which is moved relative to the stationary die by the ram or the movable die during advance movement thereof, and a cushioning device which resists the movement of the pressure pad under the thrust; of the ram or movable die.

The cushioning device ordinarily includes one or more pistons each of which is fitted in a cylinder and provided with a rod which engages the pressure pad so that movement of the pressure pad under the thrust of the ram or movable die will'causea corresponding movement of each piston in its cylinder. Each cylinder contains a fluid under sufiicient pressure to enable the piston or pistons to provide the desired resistance to movement of the pressure pad by the ram or movable die. The fluid employed is sometimes compressed air having a predetermined pressure and sometimes it is a liquid the pressure of which i is determined by a resistance through which the.

' as it is moved by the pressure pad.

When the movable die is retracted after forming an article, the compressed fluid in the cylinder or cylinders of the cushioning device will expand and cause the pressure pad to follow the movable die unless means are provided to prevent it. While the compressibility of liquid is slight relative'to that of air, the liquid in the cushioning cylinder or cylinders is capable of expanding suificiently to cause the pressure pad to be moved an appreciable distance from the position into which it was moved by the ram or movable die.

When forming metal into articles of certain shapes, it is essential that the pressure pad be prevented from immediately following the movable die during retraction thereof in order to avoid distorting or otherwise damaging the article just formed by the dies.

Both mechanical and hydraulic devices have been produced by locking the pressure pad in the position to which it is moved by the ram or die but such devices do not function accurately due to lost motionor back lash in the mechanical devices and to expansion of liquid in the hydraulic devices. Devices have also been prosuch devices require the use of both liquid and compressed air.

The present invention has as an object to pro vide a metal working press having means for accurately retaining the pressure pad thereof in the position to which it is moved by the ram or die.

Another object is to provide a metal working press having the ram actuating means and the pressure pad cushioning means energized by liquid from a single pump.

. Another object is to provide a metal working press in which the greater part of the energy consumed by the cushioning means is regenerated.

Another objectis to provide a hydraulically operated metal working press which is at least semi-automatic in operation.

Other objects and advantages will appear from the description hereinafter given of metal working presses in which the invention is embodied.

According to the invention in its general aspect, a metal working press has a pressure pad supported by a hydraulic cushioning device, the press ram during its working stroke moves the pressurepad and causesliquid to be ejected from the cushioning device through a high resistance which causes a high pressure to be created in the cushioning device, and at the end of the working stroke the pressure in the cushioning device is automatically reduced to a value which is low enough to prevent the cushioning device from causing the pressure pad to follow the ram when it starts its return stroke but which is high I enough to enable the cushioning device to sustain the pressure pad in the position to which it was moved during the working stroke.

According to the invention in another aspect, the ram of a metal working press is reciprocated by a hydraulic motor which is energized by a pump, the ram during its down stroke depresses a pressure pad, downward movement of the pressure pad is resisted by a hydraulic cushioning device from which liquid is ejected as the pres sure pad is depressed, the volurneof liquid ejected from the pressure pad is in excess of the volume of liquid delivered by the pump to the motorto cause it to move the ram downward, the cushioning device is connected to the intake of the pump and to a high pressure relief valve during the relief valve, and at the end of the down stroke the pressure in the cushioning device is automatically reduced to a value which is low enough to prevent the cushioning device from causing the pressure pad to follow the ram when it ascends but which is high enough to enable the cushioning device to sustain the pressure pad in the position to which it was depressed during the working stroke.

The invention is exemplified by the metal working presses shown schematically in the accompanying drawings in which the views are as follows:

Fig. 1 is a diagram of the hydraulic circuit of a metal working press which is operated by liquid supplied by a reversible pump, the several parts being shown in the positions occupied when the press is idle.

Fig. 2 is a diagram of an electric circuit for controlling the operation of the presses shown in Figs. 1 and 3.

Fig. 3 is a view similar to Fig. 1 but showing the press provided with a uni-directional pump and adapted to be reversed by means of a reversing valve.

Fig. 4 is a view similar to Fig. 1 but showing means for causing the pump to be supercharged by the liquid expelled from the cushioning device during the down stroke of the press ram.

Fig. 5 is a diagram of an electric circuit for controlling the operation of the press shown in Fig. 4.

Fig. 6 is a diagram showing how the circuits shown in Figs. 2 and 5 may be modified.

Fig. 7 is a diagram showing another modification of the circuits shown inFigs. 2 and 5.

Figs. 8 and 9 are views showing other characteristic positions of the pump pilot valve shown in Figs. 1 and 4.

Figs. 10 and 11 are views showing other characteristic positions of the control valve and pilot valve shown in Figs. 1 and 3.

Figs. 12 and 13 are views showing other characteristic positions of the reversing valve and its pilot valve shown in Fig. 2.

Figs. 14 and 15 are views showing other characteristic positions of the control valve shown in Fig. 4.

Fig. 16 is a view showing another position of the differential valve shown in Fig. 4.

' Figs. 1 and 2 Since the frame, platen, die, die blocks, etc., of a metal working press are well known and may be of various forms, only so much of the press structure has been schematically shown as is necessary to an explanation of the invention, and the dies have been shown as being formed integral with the bolster and with the platen or ram but it is to be understood that the press is not so constructed in practice.

For the purpose of illustration, the press has been shown as having a lower die I arranged upon a bolster 2 which is fixed in a stationary position, an upper die 3 which is carried by a ram 4, and a pressure pad 5 which is arranged around lower die I.

Ram l is'fixed to a piston 5 which is fitted in a stationary cylinder 1 and forms therewith a hydraulic motor for reciprocating ram 4 to'move die 3 toward and from die I'.

The metal to be operated upon is placed upon die I and pressure pad 5 and then die 3 is advanced. Die 3 will first press the edge of the metal against pressure pad 5 and will then cooperate with die I to form the metal into the shape determined by the contour of the dies, pressure pad 5 being depressed by die 3 during the shaping of the metal.

In order that the edge of the metal may be gripped with a predetermined force, downward movement of pressure pad 5 is resisted by a hydraulie cushioning device which includes one or more pistons 8 each of which is fitted in a stationary cylinder 9 and provided with a piston rod in which extends loosely through bolster 2 into contact with the underside of pressure pad 5. The number of pistons and cylinders required will depend upon the size and type of the dies employed. With the type of dies shown, at least four pistons and cylinders are ordinarily employed but only two havebeen shown in order to avoid unnecessary complication of the view.

Liquid for operating motor 6-! and for causing pistons 8 to raise pressure pad 5 after it has been depressed, is supplied by a. pump I I. While any suitable pump will suffice, pump 1 i has been shown as being of the rolling piston type which is fully illustrated and described in Patent No. 2,074,068. It is deemed sufiicient to state herein that pump Ii has its cylinders arranged radially in a cylinder barrel 12 which is journaled upon a stationary valve shaft or pintle l3 having ports and passages formed therein through which li'quid flows to and from the cylinders, that the outer ends of the pistons react against the angular inner surface of a reaction member carried by a thrust member or slide block i4, that no liquid will be discharged by pump II when slide block [4 is in'its central or neutral position at which time its axis coincides with the axis of cylinder barrel l2, and that pump ii will deliver liquid in a direction and at a rate dependent upon the direction and distance slide block i4 is shifted from its neutral position. As shown, pump II is adapted to deliver liquid into one and have liquid returned to it through the other of two channels i5 and I6 which are connected to pintle [3 in communication with the passages formed therein.

Since motor 6-! is of the differential type so that, when operating, liquid is discharged therefrom at rates which are always either in excess of or less than the rate required to supply pump II with liquid, channels l5 and IG communicate at points intermediate their ends with pintle I3 and have their lower ends connected, respectively. to two annular grooves or ports i1 and 18 formed in the wall of a bore 19 which is formed in a valve casing 20 and connected at a point between ports 11 and It! with a reservoir 2i through a check valve 22 and a low pressure resistance valve 23. Each of channels i5 and I6 are also connected to a high pressure relief valve which has been omitted from the drawings to avoid crowding the view.

Bore I9 contains a differential valve 24 having heads or pistons formed upon its ends and closely fitted in bore is to block one or the other of ports l1 and I8, and opposite ends of bore l9 are connected by channels 25 and 26 to channels l5 and 6 respectively.

The arrangement is such that, when pump ll discharges liquid into channel [6 to raise piston 6, pressure will extend through channel 26 to the right'end of bore l9 and shift valve 24 toward the left to the position shown to block the end of channel l6 and uncover the end of channel i5 so that the liquid expelled from cylinder 1 by piston 6 in excess of the volume required by pump ll may be discharged through resistance valve 23 into reservoir 2| and, when pump II discharges liquid into channel I5 to cause piston 6 to descend, pressure will extend through channel to the left end of bore I9 and shift valve 24 toward the right to block the end of channel I5 and uncover the end of channel I6 so that pump II may draw liquid .from reservoir 2| through check valve 22.

When slide block I4 is shifted toward the right from its neutral position, pump II will discharge liquid into channel I5 and have liquid returned to it through channel I6 and, when it is shifted toward the left from its neutral position, pump II will discharge liquid into channel I6 and have liquid returned to it through charmel I5.

Slide block I4 is at all times urged toward the right by liquid acting upon a piston which is connected to or in engagement with slide block Hand is fitted in a stationary cylinder 3| carried by the casing of pump II.

An adjusting screw 32 is threaded through the head of cylinder 3| to limit the movement of piston 30 and slide block I4 toward the left.-

by liquid acting upon a piston which is fitted in cylinder 34 and adapted to engage the outer face of piston 33.

The movement of piston 35 toward the left is limited by a collar 36 fixed on a stop rod 31 which extends loosely through pistons 33 and 35 and through the head of cylinder 34. The inner end of rod 31 is adapted to engage slide block I4 and the outer end of rod 31 is provided with a nut 38 which is adjusted to 50 position collar 36 that piston 35 when energized will move slide block I4 exactly to its neutral position.

The outer end of rod 31 is adapted to engage an adjusting screw 39 which is threaded through a cap 40 fixed to the head of cylinder 34. Turning screw 39 adjusts the distance rod 31 and slide block I4 may be moved toward the right to thereby determine the rate at which pump II will deliver liquid into channel I5.

Pistons 33 and 35 are larger than piston 30 so that slide block I4 will be moved toward the left when liquid is simultaneously supplied to both of cylinders 3| and 34 at the same pressure.

Liquid for operating pistons33 and 35 is supplied by a gear pump 4| which is ordinarily driven in unison with pump I I and arranged in the easing thereof according to the usual practice.

Gear pump 4| draws liquid from reservoir 2| and discharges it into a branched supply channel 42 at a rate in excess of requirements, the excess liquid being exhausted through a relief valve 43 which enables gear pump 4| to maintain in channel 42 a pressure equal to the resistance of relief valve 43.

Supply channel 42 has one of its branches connected to the outer end of cylinder 3| so that piston 30 is constantly urged toward the right by a constant force which is proportional to gear pump pressure.

Delivery of liquid from gear pump 4| to cylinder 34 is under the control of a pump control valve 46 having a valve member or plunger 41 fitted in a valve casing 48 to control communication between four annular grooves. or ports 49. 50, 5| and 52 formed in valve casing 46.

Port 49 has another branch of supply channel 42 connected thereto. Port 50 is connected by a channel 53 to cylinder 34 at or near the outer end thereof. Port 5| is connected by a channel 54 tocylinder 34 at a point between pistons 33 and 35. Port 52 is connected to a drain channel which discharges into reservoir 2|.

When valve member 41 is in its central position as shown in Fig. 1, pressure extends from channel 42 through valve casing 48 and channel 53 to the right end of cylinder 34 and holds piston35 against collar 36 on stop rod 31, and the space between pistons 33 and 35 communicates through channel 54 and valve casing 48, with drain channel 55 so that the pressure in cylinder 3| 'will cause piston 30 to hold slide block I4 against piston 33 and piston 33 against piston 35 in which position of slide block I4 pump II is at zero stroke and no liquid will be delivered thereby.

When valve member 41 is shifted toward the left to the position shown in Fig. 9, port 49 is blocked and channels 53 and54 are open to drain channel 55 so that liquid supplied by-gear pump 4| to cylinder 3| can cause piston 30 to move slide block I4 toward the right until rod 31 abuts adjusting screw 39 at which time pump II will discharge liquid into channel I5 at a rate determined by the adjustment of screw 39.

When valve member 41 is shifted toward the right to the position shown in Fig. 8, port 52 is blocked and channels 53 and 54 are open to port 49 so that liquid from gear pump 4| can flow through channel 42, valve casing 48 and channels 53 and 54 to cylinder 34 and cause pistons 33 and 35 to move slide block I4 toward the left until piston 30 abuts adjusting screw 32 at which time pump II will discharge liquid into channel I6 at a rate determined by the adjustment of screw 32.

. ranged, respectively, in two chambers 58 and 59 which are formed in opposite ends of valve casing 48 and connected to drain channel 55.

Valve member 41 is adapted to be shifted in one direction or the other by one or the other of two solenoids 60 and 6| the cores of which are connected, respectively, to valve stems 62 and 63 which are fixed to opposite ends of valve member 41 and extend outward through chambers 58 and 53. Solenoids 60 and 6| are controlled in a manner to be presently described.

Channel I5 has its other end connected directly to the upper end of cylinder 1 so that, when slide block I4 is moved toward the right, the liquid discharged by pump II into channel I5 will cause piston 6 to move ram 4 and die 3 downward and .thereby cause pressure pad 5 to be depressed and move pistons 8 downward in cylinders 9.

The lower end of each cylinder 3 is connected by a channel 65 to the inlet of a resistance valve 66 the outlet of which is connected to drain channel 55 so that, when pressure pad 5 moves downward, pistons 8 will expell liquid from cylinders 9 through resistance valves 66 which resist When slide block I4 is moved toward the left, i

the liquid discharged by pump II into channel I6 is directed either to the lower end of cylinder 1 or to the lower ends of cylinders 9 by means of a control valve 61 having a valve member or plunger 68 fitted in a valve casing 69.

Valve member 68 controls communication between five annular grooves or ports I0, II, 12, I3 and I4 which are formed in the inner wall of casing 09.

Port I is connected by channel I6 to one port of pump I I. Port II is connected to the lower end of ram cylinder I by a channel I5 having a resistance valve 16 and a check valve 'I'I connected therein in parallel with each other and adapted to open in opposite directions. Check valve 11 permits liquid to flow freely to the lower end of cylinder I but prevents liquid from flowing therefrom except through resistance valve I6 which ofiers enough resistance to the discharge of liquid from the lower end of cylinder 1 to prevent piston 6 from descending until forced downward by liquid supplied to the upper end of cylinder I.

Ports I2 and I3 have two channels I8 and I9 connected thereto respectively, and port 14 is connected by a channel 80 to the inlet of a low pressure relief valve 8| the outlet of which is connected by a channel 82 to drain channel 55.

Channel I8 is connected to each of channels 65 through a check valve 83 which permits liquid to flow freely from channel I8 into channel 65 but prevents liquid from flowing from channel 65 into channel 18, and channel 19 is connected to each of channels 85 through a check valve 04 which permits liquid to flow freely from channel 65 into'channel I9 but prevents liquid from flowing from channel 19 into channel 85 so that, when valve member 88 is in the position shown in Fig. 11, liquid from pump II may flow through I channel I6, valve 61, channel I8, check valves 83 and channels 65 to the lower ends of cylinders 9 and cause pistons 8 to raise pressure pad 5 and, when valve member 68 is in the position shown in Fig. 10, liquid may escape from cylinders 9 through low pressure relief valve 8| and thereby drop the pressure in cylinders 9 to a value capable of" supporting pressure pad 5 but incapable of causing pressure pad 5 to follow die 3 when it ascends but, when pressure pad 5 is being moved downward and causing pistons 8 to eject liquid from cylinders 9 through resistance valves 66, check valves 03 and '84 will prevent liquid from flowing from a cylinder 9 containing liquid under a high pressure to a cylinder 9 containing liquid under a lower pressure and thereby enable resistance valves 08 to maintain different pressures in the several cylinders 9. I

Valve member 88 is normally held in its central or neutral position by two springs 85 and 08 arranged, respectively, in two chambers 81 and 88 formed in opposite ends of valve casing 89, and it is adapted to be shifted in one direction or the other by liquid supplied to one or the other of chambers 81 and 88 and acting upon one end or the other of valve member 88. 1

The delivery of liquid to chambers 81 and 88 is under the control of a pilot valve 89 having a valve member or plunger 90 arranged in a valve casing 9| and controlling communication between five ports 92, 98, 84, 95 and 90.

Port 82 has a branch of gear pump supply channel 42 connected thereto, port 93 is connected to chamber 81 by a channel 91, port 94 is connected to chamber 88 by a channel 98, and

ports 95 and 96 have drain channel 55 connected thereto.

Valve member is normally held in its central or neutral position by two springs 99 and I00 arranged, respectively, in two spring chambers IOI and I02 which are formed in opposite ends of valve casing 9| and have drain channel 55 connected thereto to prevent liquid or air from being trapped therein. I

Valve member 90 is adapted to be shifted in one direction or the other by one or the other of two solenoids I03 and I04 arranged at opposite ends of valve casing 9| and having the cores thereof connected to suitable valve stems which extend through the spring chambers and are fixed to opposite ends of valve member 90.

When solenoid I04 is energized, it will shift valve member 90 to the position shown in Fig. 10 and then liquid from gear pump 4| will flow through channel 42, pilot valve 89 and channel 91 to chamber 81 and shift control valve member 68 to the position shown in Fig. 10 to open port I3 to port I4 so that liquid may escape from cylinder 9 through low pressure relief valve 8|.

When solenoid I03 is energized, it will shift valve member 90 to the position shown in Fig. 11 and then liquid from gear pump 4| will flow through channel 42, pilot valve 89 and channel 98 to chamber 88 and shift control valve member 68 to the position shown in Fig. 11 to open port 12 to port I0 so that liquid from pump II may flow through channel I6, valve 61, channel 18, check valves 83 and channels 65 to the lower ends of cylinders 9 and cause pistons 8 to raise pressure pad 5.

The electric'circuit Referring now more particularly to Fig. 2, current for energizing solenoids 60 and 6| is supplied thereto under the control, respectively, of two contactor switches A and B from a power line shown as consisting of two conductors IIO and III, and current for energizing solenoids I03 and I04 is supplied thereto under the control, respectively, of two contactor switches C and D from power line IIOI I I. 1

Contactor switch A includes three switches Al, A2 and A3 and an electro-magnet A4 for operating its switches, contactor switch 13 includes three switches BI, B2 and B3 and an electromagnet B4 for operating its switches, contactor switch C includes two switches CI and C2 and an electro-magnet C3 for operating its switches, and contactor switch D includes three switches DI, D2 and D3 and an electro-magnet D4 for operating its switches.

In order to simplify the drawing, contactor switches A, B, C and D have been shown arranged horizontally but in practice they are arranged vertically so that, when the magnets are deenergized, the switches will open by gravity to the positions shown.

Contactor switch A is controlled in part by a normallyopen manually operable starting switch II2 and in part by a switch SI which may either be a limit switch LSI (Fig. 1), which is operated by pressure pad 5 at the end of its downward movement, or it may be a pressure responsive switch PSI which operates in response to a predetermined maximum pressure in the upper end of the ram cylinder as by being connected to channel I5 as shown in Fig. 1.

Contactor switch 13 is controlled in part by switch SI and in part by a limit switch LS2 which is operated by pressure pad 5 when it reaches the limit of its upward movement as shown in Fig. 1. Switch B may also be controlled in part-by a pressure responsive switch as will presently be explained in connection with an explanation of the operation of the press.

Contactor switch C is controlled in part by limit switch LS2 and in part by a limit switch LS3 which is operated by die 3 when it reaches the limit of its upward movement as shown in Fig. 1.

Contactor switch D is controlled in partby switch SI and in part by limit switch LS3.

In order that the press may be stopped at any time, the circuit is provided with a. normally closed manually operable stop switch H3 which has one of its terminals connected to conductor III by a conductor H4 and its other terminal connected by a conductor II5 to one terminal of starting switch H2, to two opposed terminals of switch SI, to one terminal of switch LS2 and to one terminal of switch LS3. The other terminal of switch .I I2 is connected by a conductor II6 to one end of the winding of magnet A4 the other end of which is connected to conductor IIO by a conductor II'I so that, when switch H2 is closed, magnet A4 will be energized and close switches AI, A2 and A3.

Switch AI has one of its terminals connected to conductor I I0 by a conductor I I8 and its other terminal connected to one end of the winding of solenoid 60 the other end of which is connected to one terminal of switch A2. The other terminal of switch A2 is connected to conductor III by a conductor H9.

Switch A3 has one of its terminals connected.

by a conductor I20 to conductor II 6 intermediate the ends thereof and its other terminal connected V to a third terminal of switch SI by a conductor I2I.

The fourth terminal of switch SI is connected by a conductor I22 to one end of the winding of magnet B4-the other end of which is connected to conductor H0 by a conductor I23.

The fourth terminal of switch SI is also connected by a conductor I24 to one terminal of switch C2 and normally connected through switch C2 to one end of a conductor I24. The other end of conductor I24 is connected toone end of the winding of magnet D4 the other end of minal of which is connected to conductor I24 by a conductor I34.

Switch CI has one of its terminals connected to conductor I I0 by a conductor I35 and its other terminal connected to one end of the winding of solenoid I03 the other end of which is connected to one terminal of switch B2. The other terminal of switch B2 is connected to conductor III by a conductor I21.

Switch B3 has one of its terminals connected by a conductor I28 to conductor I22 intermediate the ends thereof and its other terminal connected to a second terminal of switch LS2 by a. conductor I29. The second terminal of switch LS2 is also connected by a conductor I30 to the terminal of switch LS3 opposite the terminal to which conductor H5 is connected.

A third terminal of switch LS3 is connected by a conductor I3I to one end of the winding of magnet C3 the other end of which is connected to conductor I'I0 by a conductor I32. The fourth terminal of switch LS3 is connected by conductor I33 to one terminal of switch D3 the other terto a third terminal of switch C2. The fourth terminal of switch C2 is connected to conductor III by a conductor I36.

Switch DI has one of its terminals connected to conductor IIO by a conductor I31 and its other terminal connected to one end of the winding of solenoid I04 the other end of which is connected to one terminal of switch D2. The other terminal of switch D2 is connected to conductor I I I by a conductor I38.

If it is desired to provide the press with both a limit switch and a pressure responsive switch as shown in Fig. 1, the two switches may be alternatively connected into the circuit by means of a suitable selector switch.

For the purpose of illustration, switches LSI and PSI have been shown in Fig. 6 as being adapted to be connected into the circuit by means of a double throw two pole selector switch I40. As shown, conductor I2I is connected to the center terminal on one side of switch I40 and the two end terminals on the same side of switch I40 are connected to corresponding terminals of switches of LSI and PSI, respectively, by two conductors MI and I42, and conductor I22 is connected to the other center terminal of switch I40 and the other two end terminals of switch I40 are connected to corresponding terminals of switches LSI and PSI, respectively, by two conductors I43 and I44.

It will be obvious that either one of the two switches LSI and PSI may be rendered operative and the other inoperative by moving switch I40 from one to the other of its two positions, switch LSI being moved' out of the path of its actuator when switch PSI is operative.

Operation Assuming that the several parts are in the positions shown in Figs. 1 and 2, that pumps I I and M are running and that a metal blank is arranged upon die I and pressure pad 5, the press will operate as follows:

When starting switch H2 is closed, a circuit will be established from conductor .I II through conductor H4, stop switch H3, conductor H5, switch H2, conductor H6, magnet A4 and conductor I I! to conductor IIO, thereby energizing magnet A4 which will close switches Al, A2 and A3. i

The above circuit will be broken when switch H2 is released but, as soon as switch A3 closes, it will establish a circuit from conductor IIO through conductor II I, magnet A4, conductors H0 and I20, switch A3, conductor I2I and switch SI to conductor H5 which is always connected to conductor III as long as switch II3 remains closed, thereby preventing magnet A4 from being deenergized when starting switch I I2 opens.

Closing switches AI and A2 establishes a circuit from conductor IIO through conductor H0, switch AI, solenoid 60, switch A3 and'conductor H9 to conductor III, thereby energizing sole noid 60 which will shift plunger 41 of pump control valve 46 to the position shown in Fig. 9 to connect channels 53 and 54 to drain channel 55 so that the liquid supplied to cylinder 3I by gear pump .4I may shift slide block I4 toward the right and cause pump II to discharge liquid into channel I5, and pressure will extend from channel I through channel 25 to the left end of bore I9 and shift difierential valve 24 toward the right.

The liquid discharged by pump II will flow through channel I5 to the upper end of cylinder I and cause piston 6 to move die 3 downward, and it will expel liquid from the lower end of cylinder I through resistance valve I6, channel I5, valve 61 and channel I6 to the intake of pump II, the additional liquid required by pump II, being drawn from reservoir 2| through check valve 22 and differential valve casing 28.

Just after die 3 starts downward, limit switch LS3 operates to disconnect conductor I3I' from conductor I36 and to connect conductor I33 to conductor II5 but this has no effect at this time.

When die 3 engages the blank, it will press the edge portion thereof against pressure pad 5 and then move pressure pad 5 downward and force the blank over die I to form it into a desired shaped. Just after pressure pad 5 starts downward, limit switch LS2 operates to connect conductors I29 and I30 to conductor H5 but this has no effect at this time.

As pressure pad 5 moves downward, it causes pistons 8 to expel liquid from cylinders 9 through channels 65 and resistance valves 66 into drain channel 55. Resistance valves 66 will resist the discharge of liquid therethrough and thereby cause the edge portion of the blank to be firmly gripped between pressure pad 5 and die 3.

When the blank has been formed into the desired shape, switch SI is operated to disconnect conductor I2I from conductor H5 and to connect conductors I22 and I24 to conductor II5. If switch SI is a limit switch, it is operated when die 3 or pressure pad 5 reaches a predetermined point in its downward movement. If switch SI is a pressure responsive switch, it operates when die 3 is pressing the metal against die I with a predetermined force.

Disconnecting conductor I2I from conductor I I5 breaks the circuit through magnet A4 so that magnet A4 is deenergized and switches AI, A2 and A3 open, thereby deenergizing solenoid 6|].

Connecting conductor I22 to conductor II5 establishes a circuit from conductor I I5 through switch SI, conductor I22, magnet B4 and conductor I23 to conductor III] and causes magnet B4 to be energized, and it establishes a circuit from conductor II5 through switch SI, conductor I24, switch C2, conductor I24, magnet D4 and conductor I25 to conductor H6 and causes magnet D4 to be energized.

Magnet B4 will close switches BI, B2 and B3 to establish a circuit from conductor I I6 through conductor I26, switch BI, solenoid 6I, switch B2 and conductor I21 to conductor III so that solenoid BI is energized, and to establish a circuit from conductor II5 through switch LS2, conductor I29, switch .33, conductors I28 and I22, magnet B4 and conductor I23 to conductor IIIl so that magnet B4 will not be deenergized when switch SI is returned to its initial position.

Magnet D4 will close switches DI, D2 and D3 to establish a circuit from conductor II6 through conductor I31, switch DI, solenoid I64, switch D2 and conductor I36 to conductor III, so that solenoid I04 is energized, and to' establish a circuit so that magnet D4 will not be deenergized should switch SI disconnect conductor I24 from'conductor II5 when die 3 starts upward.

Energizing solenoid I04 will cause it to shift plunger 96 of pilot valve 89 to the position shown I in Fig. 10 and then liquid from gear pump 4| will flow through channel 42, valve 89 and channel 91 to chamber 81 and shift plunger 68 of control valve 61 to the position shown in Fig. 10, thereby opening channel I9 to channel 86 so that enough liquid can escape from cylinders 8 through low pressure relief valve 8| to cause the pressure in cylinders 8 to drop to a value which is low enough to prevent pistons 8 from moving pressure pad 5 upward when die 3 ascends but which is high enough to support pressure pad 5 in the position to which it was moved by die 3.

Deenergizing solenoid 60 and energizing solenoid 6| causes solenoid 6| to shift plunger 41 of valve 46 to the position shown in Fig. 8 and then liquid from gear pump 4I flows through channel 42, valve 46 and channel 54 to cylinder 34 and causes piston 33 to shift slide block I4 toward the left and thereby reverse pump I I.

Liquid from pump II will then flow through channel I6, valve 61, channel '15 and check valve 11 to the lower end of cylinder I and cause piston 6 to raise die 3 and pressure will extend from channel I6 through channel 26 to the right end of bore I9 and shift diflerential valve 24 to the position shown so that, as piston 6 moves upward and expels liquid from the upper end of cylinder I, the liquid expelled from cylinder I in excess of the volume required by pump II may be exhausted through bore I9 and resistance valve 23 into reservoir 2|.

Solenoids BI and I04 are energized simultaneously so that valve plungers 41 and are shifted and cause gear pump pressure to be applied to piston 33 and to the end of valve plunger 68 substantially simultaneously. However, valve plunger 68 will be shifted almost instantly but there will be a slight delay in shifting slide block I4 due to its inertia. While this delay is very slight. it is sufficient to permit the pressure in cylinders 8 to drop to the desired low value.

However, if pump II should tend to reverse too quickly, reversal thereof may be delayed either by delaying the operation of valve 46 or by delaying the energization of solenoid 6|.

The operation of valve 46 may be delayed by connecting a choke into channel 54 in the well known manner and as shown in Fig. 3 in which the operation of a reversing valve is delayed by a choke.

Energization of solenoid 6| may be delayed by a pressure responsive switch which remains open until the pressure inv cylinders 8 has dropped to substantially the desired low value. As shown in Fig. 7, conductor I22 is divided into two parts and the adjacent ends of the two parts are connected to the terminals of a switch I45 which is urged toward closed position by a spring I46 the tension of which is adjusted by a screw I41 threaded through a stationary abutment I48.

Switch I45 is adapted to be opened by a piston I49 fitted in a cylinder I56 which is connected to channel I9.

The arrangement is such that, when pressure pad 6 is moved downward and causes a high pressure to be created in cylinders 8, pressure Will extend through channels 65, check valves 84 and channel I9 to cylinder I56 and cause piston I49 to open switch I 45, thereby preventing magnet B4 from being energized when switch SI operates. As soon as the pressure in cylinders 8 is reduced to the desired low value, spring I46 will close switch I45 and cause magnet B4 to be energized and cause switches BI and B2 to close and energize solenoid 6|.

When die 3 reaches its upper position, it operates limit switch LS3 to disconnect conductor I33 from conductor H and to connect conductor I3I to conductor I30.

If switch SI disconnects conductor I24 from conductor I I5 when die 3 starts upward, which it would probably do if it were a pressure responsive switch, disconnecting conductor I 33 from conductor II5 would break the circuit through magnet D4 and thereby deenergizing it but, if switch SI were a limit switch and did not disconnect conductor I24 from conductor II5 when die 3 moved upward, disconnecting conductor I33 from conductor I I5 would not deenergize magnet D4 as a circuit therethrough is maintained by switch C2.

Connecting conductor I3I to conductor I30 establishes a circuit from conductor II5 through switch LS2, conductor I30, switch LS3, conductor I3I, magnet C3, and conductor I32 to conductor H0, thereby causing magnet C3 to be energized.

Magnet C3 will operate switches CI and C2 to connect opposite ends of solenoid I03 to conductors I35 and I36, so that solenoid I03 is energized, and to disconnect conductor I24 from conductor I24 so that magnet D4 is deenergized and permits switches DI and D2 to open and deenergize solenoid I04.

Deenergizing solenoid I04 and energizing solenoid I03 causes solenoid I03 to shift plunger 90 of pilot valve 89 to the position shown in Fig. 11 so that liquid from gear pump 4I may flow through channel 42, valve 89 and channel 98 to chamber 88 and shift plunger 68 of control valve 61 to the position shown in Fig. 11 and then liquid from pump II will flow through channel I6, valve 61, channel 18, check valves 83 and channels 65 to cylinders 9 and cause pistons 8 to raise pressure pad 5.

As pressure pad 5 starts upward, switch SI, if a limit switch, will operate to disconnect conductors I22 and I24 from conductor II5 and to connect conductor I2I to conductor II5 but this has no effect until the press starts another cycle. of operation.

When pressure pad 5 reaches its upper limit,

. it operates limit switch LS2 to disconnect conductors I29 and I30 from conductor II5, thereby deenergizing magnets B4 and C3 so that switches CI, C2, BI and B2 may operate to deenergize solenoids 6I and I03.

Deenergizing solenoid I03 permits spring I00 to move plunger 00 of pilot valve 89 to its neutral position so that chambers 81 and 88 are open to drain channel 55 and spring 85 is permitted to shift plunger 68 of control valve 61 to its neutral position as shown in Fig. 1.

Deenergizing solenoid 6I permits spring 51 to shift plunger 41 of valve 46 to its neutral position as shown in Fig. 1, thereby connecting channel 54 to drain channel 55 so that gear pump liquid acting upon piston 30 may move slide block I4 to its neutral position and cause the press to come to rest upon the parts thereof in' the proper positions to start a second cycle of operation when switch I I2 is closed.

Fig. 3

by a unidirectional pump and reversed through a reversing valve. Consequently, like parts have been indicated by like reference numerals, so that further description thereof is unnecessary, and corresponding parts have been indicated by corresponding reference numerals with the exponent' a added thereto.

As shown, the press is powered by a unidirectional pump I5I which is driven at a substantially constant speed from a power source (not shown) and delivers liquid into a channel I52 and has liquid returned to it through a. channel I53. In order to protect the pump from developing excessive pressures, a high pressure relief valve I54 is connected to the outlet of the pump and discharges into reservoir 2|.

Since the volume returned to the pump from the circuit is always greater or less than the volume discharged by the pump when the press is in operation, a check valve 22 and a low pressure resistance valve 23 are connected to the intake of the pump and extend into reservoir 2|- so that, when piston 6 moves downward, pump I5I may draw additional liquid from reservoir 2| through check valve 22 and, when piston 6 moves upward, the liquid expelled thereby from cylinder I in excess of pump requirements may be exhausted through resistance valve 23 into reservoir 2|.

The liquid discharged by pump I5I is directed either into channel I5 or into channel I6 by a reversing valve I55 fitted in a bore l56iwhich is formed in a valve casing I51 and has four annular grooves or ports I58, I58, I60 and I6I formed in the wall thereof. Channel I52 is connected to port I58. Channel I53 is divided into two branches one of which is connected to port I59 and the other of which is connected to the left end of bore I56, the other end of bore I56 being connected to a branch of drain channel 55.

Channel I5, which has one of its ends connected to the upper end of ram cylinder I, has its other end connected to port I60. Channel I6, which has one of its ends connected to port 10 in control valve 61, has its other end connected to port Reversing valve I55 is urged toward and normally held in its central or neutral position by a caged spring I62 arranged in a spring chamber I63 which is fixed to the left end of valve casing I51. Spring I62 acts upon a valve stem I64 which is fixed to the left end of valve I55 and extends through chamber I53. I

Reversing valve I55 is adapted to be shifted in one direction or the other by a hydraulic servomotor consisting of a cylinder I65, which is fixed to the right end of valve casing I51, and a piston I66 which is fitted in cylinder I65 and connected by a suitable valve stem to valve I55.

Servo-motor I65-I66 is energized by liquid supplied thereto by gear pump 4I underthe control of a pilot valve I19 having a valve'member or plunger I arranged in a casing I8I and controlling communication between five annular grooves or ports I82, I83, I84, I and I86 which are formed in the inner wall of casing I8I.

Port I82 has gear pump supply channel 42 connected thereto, ports I83 and I84 have drain channel 55 connectedthereto, port I85 is connected by a channel I01 to the innerend of cylinder I 65, and port I86 has connected thereto a channel I88 having two branches one of which is connected to the extreme right end of cylinder I65 through a choke I89 and the other of which is connected to a port I90-formed in the wall of cylinder I65 and so located that it is covered by piston I66 as soon as piston I66 moves toward the right from its central or neutral position. Cylinder I65 also has its right end connected to drain channel 55 through a check valve I9I which permits liquid to be drawn from channel 55 into cylinder, I65 but prevents liquid from being expelled from cylinder I65 directly into channel 55.

The arrangement is such that, when valve member I80 of pilot valve H9 is in the position shown in Fig. 3, port I82 is blocked and both ends of cylinder I65 are open to drain channel 55 through channels I81 and I88 and pilot valve I19 so that reversing valve I55 is held in its central or neutral position by spring I62 in which position of valve I55 channel I52 is open to return channel I53 through bore I56 so that pump II is bypassed.

Pilot valve member I80 is urged toward and normally retained in its central or neutral position by two springs I92 and I93 arranged, respectively, in two spring chambers I94 and I95 which are formed in opposite ends of valve casing I8I and have'drain channel 55 connected thereto to prevent liquid or air from being trapped-therein.

Valve member I80 is adapted to be shifted in one direction or the other by one or the other of two solenoids I50 and I5I arranged at opposite ends of valve casing I8I and having the cores thereof connected to suitable valve stems which extend through the spring chambers and are fixed to opposite ends of valve member I80. Sole noids 60 and BI correspond, respectively, to solenoids 60 and BI (Figs. 1 and 2) and are connected into the'electric circuit and controlled in the same manner as solenoids 60 and BI.

The press is controlled by the electric circuit shown in ,Fig. 2 and it operates in exactly the same manner as the press shown in Fig. 1 except that the flow of liquid is reversed by means of a reversing valve instead of reversing the pump, and choke I89 functions to delay the movement of the reversing valve in one direction.

When starting switch H2 is closed, solenoid 60 will be energized in the previously described manner and will shift pilot valve member I 80 toward the left to the position shown in Fig. 12 so that liquid from gear pump 4| may flow through channel 42, valve casing I8I and channel I88 to the right end of cylinder I65 and cause piston I 66 to shift reversing valve I55 toward the left to the position shown in Fig. 12'.

Liquid from pump I5I will then flow through channel I52, bore' I56 and channel I5 to the upper end of ram cylinder I and cause piston 6 to move die 3 downward. Limit switches LS3 and LS2 will operate during downward movement of die" 3 and switch SI will be operated when die 3 reaches the end of its down stroke as previously explained.

Operating switch SI will cause solenoid 69 to be deenergized and solenoid M and I04 to be energized in the previously described manner.

Solenoid I04 will shift valve member 90 of pilot valve 89 to the position shown in Fig. 10, thereby causing valve'member 68 of control valve 61 to be shifted to the position shown in Fig. 10 so that liquid can escape from cylinders 8 through low pressure relief valve 8I as previously explained Solenoid 6I will shift pilotvalve member I80 toward the right to the position shown in Fig. 13 so that liquid from gear pump 4| may flow through channel 42, valve casing IBI and channel I 8I to the left end of cylinder I65 and cause piston I66 to move reversing valve I toward the right to the position shown in Fig. 13, thereby causing the liquid discharged by pump I5I to flow through channel I6, control valve 61, channel I5 and 'check valve 11 to the lower end of ram cylinder 1 and move piston 6 and die 3 upward.

Piston I66 will move at high speed and eject liquid from the right end of cylinder I through channel I88 and pilot valve casing I8I into drain channel 55 until reversing valve I55 reaches its neutral position and bypasses pump I5I and then piston I66 will cover port I90 so that liquid must When die 3 reaches its upper position, it oper ates limit switch LS3 to deenergize solenoid I04 and energize solenoid I03 so that valve plungers 90 and 68 are shifted and then the liquid discharged by pump I5I will enter cylinders 9 and cause pistons 8 to raise pressure pad 5 as previously explained.

When pressure pad 5 reaches its upper limit, it operates limit switch LS2 to deenergize solenoids I03 and 6| in a previously described manner. Deenergizing solenoid I03 permits spring I00 to move pilot valve plunger 90 to its neutral position and then spring will move control valve plunger 68 to its neutral position as previously explained.

Deenergizing solenoid 6| permits spring I62 to shift reversing valve I55 to its neutral position to bypasspump I5I and stop the press, piston I66 drawing liquid from drain channel 55 through check valve I9I into cylinder I65 as valve I55 moves toward its neutral position.

Figs. 4 and 5 The press shown in Fig. 4 is the same as the press shown in Fig. 1 except that means are provided for regenerating the greater part of 'the power required to resist the downward movement of the pressure pad. Consequently, like parts have been indicated by likereference numerals, so that further description thereof is unnecessary, and corresponding parts have been indicated by corresponding (reference numerals with the exponent b added thereto.

In order that the greater part of the power required to resist downward movement of pressure pad 5 may be regenerated, cylinders I and 9 are so proportioned that the volume of liquid expelled from cylinders 9 by pistons 8 during downward movement of pressure pad 5 is greater than the volume delivered by pump II to the upper end of ram cylinder 1 to cause piston 6 to move die 3 and pressure pad 5 downward, the liquid expelled from cylinders 9 is directed to the intake of pump H and the liquid expelled from'flcylinders 9 in excess of the liquid required to supercharge pump II is forced through a high pressure relief valve.-

Pump II and its control valve 46 are the same as the pump and the pump control valve shown in Fig. 1 and they are operated and controlled in exactly the same manner. However, since pump II is supplied during a part of a cycle of operation with liquid from cylinders 9, the liquid expelled from ram cylinder I by piston Bis directed through drain channel 55 into reservoir 2 I.

Therefore, instead of connecting pump II to res ervoir 2| through a differential valve 20-24 as shown in "Fig. 1, its two ports are connected, respectively, to the outlets of two check valves 20I and 202, which permit pump II to draw liquid from reservoir 2| in either directionpf pump delivery, and to 'the inlet of two high pressure'relief valves 203 and 204 which protect the pump from developing excessive pressures in either direction of pump delivery.

Liquid is delivered from pump I I either to the lower end of ram cylinder 1 or to pressure pad cylinders 9 under the control of a valve 6I having a valve member or plunger 68 fitted in a valve casing 69 and controlling communication between six annulargrooves or ports 10, I l 12 13 I4 and 205 which areformed in the inner wall of casing 69. h

Port 10 is connected by channel I6 to one port of pump II port II is connected to thelower end of ram cylinder I by a channel 15 having a resistance valve I6 and a check valve '11 connected therein in parallel with each other and adapted to open in opposite directions, port I2 has one end of a channel I8 connected thereto,

port 13 has one end of a channel 19 connected thereto, port I4 is connected to the inlet of low pressure resistance valve 8| which discharges into drain channel 55 and has only enough re-.

69 and it is adapted to be shifted in one direction or the other by liquid su plied to one or the other of chambers 81 and 88 and acting upon one end or the other of valve member 68''. The delivery of liquid to chambers 81" and I38 is controlled by pilot valve 89 which is connected into the circuit and functions in exactly the same manner as in the circu t shown in Fig. 1.

Instead of channel I5 connecting one port of .the pump directly to the upper end of the ram cylinder as in the press shown in Fig. 1, it connects one'port of pump I to one end of a valve casing 206 which has two ports 201. and 208 formed therein intermediate the ends thereof,

its other end connected to channel I5 by a channel 209, and a valve 2I0 fitted therein to control the flow of liquid thereto, port 201 being connected by a channel 2| I to the upper end of ram cylinder 1 and-port 208 having drain channel 55,

connected thereto.

The arrangement is such that, when-pump II discharges liquid through channel I5 at which t me valve plunger 68 is in the position shown in Fig. 14, liquid will flow through channel I5 to valve casing 206, shift valv'e 2I0 to the position shown in Fig. 16 and then flow through casing 206 and channel 2 to the upper end of cylinder I and cause piston, 6 to move downward and expel liquid from the lower end of cylinder 6 throu h resistance valve 16, channel 15 and valve 81 into drain channel 55.

When pump II discharges liquid into channel I6 at which time valve plunger 68 is in the position shown in Fig. 15, liquid will flow through channel I6, control'valve 61, channel 15 and check valve 11 to the lower end of cylinder 1 and pressure will extend through channel 209 to the right end of valve casing '206 and shift valve 2I0 to the position shown in Fig. 4. The liquid dethe upperend of cylinder I through channel 2 v and valve casing 206 into drain channel 55.

In order to maintain pressure in the several.

cylinders 8 during downward movement of pressure pad 5, and in order that the pressure in one cylinder maybe varied relative to the pressure in I another cylinder, channel I8 is connected intermediate its ends to the inlet of a high pressure relief valve 2I2, the outlet of which is connected to drain channel 55, and each cylinder 9 is connected by a channel I to the inlet of a low pressure resistance valve 66 the outlet of which is connected to channel 18. I

In order that liquid may escape from cylinders 8 through low pressure resistance valve 8| when valve plunger 68 is in the position shown in Fig. 15, each channel 65 is connected to channel I9? through a check valve 84 and, in order that liquid may be delivered to cylinders 9 when valve plunger 68' is in the position shown in Fig. 4, each channel 65 is connected to channel 18 through a. check valve 83.

The electric circuit Referring now more particularly to Fig. 5, solenoids and I03 are controlled by. a contactor switch F having three switches Fl, F2 and F3 and a magnet F4 for operating the switches, solenoid 6| is controlled by a contactor switch G having three switches GI, G2 and G3 and a magnet G4 4 normally closed manually operable switch 220 which may be opened to stop the press at any time, a normally open starting switch 22l, a

switch SI which is operated at the end of the downward movement of die 3 and which may be either a limit switch or a pressure responsive switch as previously explained, a limit switch LS2 which is operated'by-pressure pad 5 at-the limit of its upward movement, and a limit switch LS3 which is operated by die 3 at the end of its upward movement.

Current for energizing the solenoids and the magnets is supplied from a suitable source such as a power line which has been representated by two -conductors 222 and 223. Stop switch 220 has one of its terminals connected by conductor 224 to conductor 223 and its other terminal connected by a conductor 225 to one terminal of starting switch 22I, to two opposed terminals of switch SI, to one terminal of switch LS2 and to one terminal of switch L'SR.

The second terminal of switch MI is connected by conductor 226 to one end of the winding of magnet F4 the other end of which is connected to conductor 222 by a conductor 221 so that closing switch 22| will cause magnet F4 to be energized and close switches Fl, F2 and F3.

Switch FI has one of its terminals connected to conductor 222 by a conductor 228 and: its other terminal connected to one end of each of the windings of the solenoids 60 and I03 the other ends of which are connected to one terminal of switch F2. The other terminal of switch F2 is connected to conductor 223 by a conductor 229 so that solenoids 60 and I03 are energized when switches F! and F2 are closed.

Switch F3 has one of its terminals connected by a conductor 230 to conductor 226 intermediate the ends thereof and its other terminal connected to a third terminal of switch S! by a conductor 23!.

The fourth terminal of switch S! is connected by a conductor 232 to one end of the winding of magnet G4 the other end of which is connected to conductor 222 by a conductor 233.

The fourth terminal of switch S! is also connected by a conductor 234 to one terminal of switch G3 a second terminal of which is connected to one end of a conductor 235. The other end of conductor 235 is connected to one end of the winding of magnet H4 the other end of which Switch GI has one of its terminals connected.

to conductor 222 by a conductor 239 and its other terminal connected to one end of the winding of solenoid 6! the other end of which is connected to one terminal of switch G2. The other terminal of switch G2 is connected to conductor 223 by a conductor 240.

Switch H! has one of its terminals connected to conductor 222 by a conductor 24! and its other terminal connected to one end of the winding of solenoid I04 the other end of which is connected to one terminal of switch H2. The other terminal of switch H2 is connected to conductor 223 by a conductor 242. Switch H3 has one of its terminals connected by conductor 243 to conductor 235 intermediate the 'ends thereof and its other terminal connected by a conductor 244 to the second terminal of limit switch LS3 in order to maintain a holding circuit through magnet H4 when switch SI operates.

Operation Assuming that the several parts are in the positions shown in Figs. 4 and 5, that pumps I! and 4! are running and that a metal blank is arranged upon die I and pressure pad 5, the press will operate as follows:

When starting switch 22! is closed, a circuit will be established from conductor 223 through conductor 224, stop switch 220, conductor 225,

switch 22!, conductor 226, magnet F4 and conductor 22'! to conductor 222, thereby energizing magnet F4 which will close switches FI, F2 and F3.

The above circuit will be broken when switch 22! is released but, as soon as switch F3 closes,.

it will establish a circuit from conductor 222 through conductor 221, magnet F4, conductors 220 and 230, switch F3, conductor 23! and switch S! to conductor 225 which is aways connected to conductor 223 as long as switch 220 remains closed, thereby preventing magnet F4. from being deenergized when starting switch 22! opens.

Closing switches F! and F2 establishes a circuit from conductor 222 through conductor 228, switch FI, solenoids 60 and I03, switch F2 and conductor 229 to conductor 223, thereby energizing solenoids 60 and I03.

Solenoids I03 when energized will shift pilot valve plunger to the position shown in Fig. 11 and then liquid from gear pump 4! will flow through channel 42, pilot valve 89 and channel 98 to chamber 88 and shift control valve plunger 68 to the position shown in Fig. 14.

Solenoid 60 when energized will shift plunger 4'! of pump control valve 46 to the position shown in Fig. 9 and thereby cause pump II to draw liquid from reservoir 2! through check valve 202 and discharge it into channel I5. This liquid will flow through channel I5 to valve casing 206 and shift valve 2I0 to the position shown in Fig. 16 and then the liquid will flow through valve casing 206 and channel 2!! to the upper end of ram cylinder I and cause piston 6 to move die 3 downward. Piston 6 in moving downward will expel liquid from the lower end of cylinder through resistance valve I6, channel I5 and control valve 61* into drain channel 55.

When die 3 engages the blank, it will press the edge portion thereof against pressure pad 5 and then move pressure pad 5 downward and force the ,blank over die I to form it into a desired shape." Just after die 3 starts downward, limit switch LS3 operates to connect conductor 244 to conductor 225 and, just after pressure pad 5 starts downward, limit switch LS2 operates to connect conductor 238.to conductor 225 so that switches G and H will be operated when switch S! is operated.

As pressure pad 5 is moved downward by die 3, it causes pistons 8 to expel liquid from cylinders 9 through channels 65 and low pressure resistance valves 66 into channel 18*. Enough of this liquid to supply pump II flows through channel 18 control valve 61 and channel I6 to the intake of pump II and the remainder is expelled through high pressure relief valve 2!? into drain channel 55.

The arrangement is such that the pressure in each cylinder 9 is equal to the resistance of the resistance valve 63* connected thereto plus the resistance of relief valve 2I2 so that the liquid in cylinders 9 resist the downward movement of pressure pad 5 and thereby causes the edge portion of the blank to be firmly gripped between pressure pad 5 and die 3, and pump I! is supercharged at a pressure equal to the resistance of high pressure relief valve 2!2, thereby regenerating the greater part of the energy expended in resisting downward movement of pressure pad 5.

When the blank has been formed into the desired shape, switch S! is operated to disconnect conductor 23! from conductor 225 and to connect conductors 232 and 234 to conductor 225. If switch S! is a limit switch, it is operated when die 3 and pressure pad 5 reach predetermined points in their downward movements. If switch S! is a pressure responsive switch, it operates when die 3 is pressing the metal against die I with a predetermined force.

Disconnecting conductor 23! from conductor 225 breaks the circuit through magnet F4 so that magnet F4 is deenergized and switches FI, F2 and F3 open, thereby deenergizing solenoids 60 and I03.

Connecting conductor 234 to conductor 225 establishes a circuit from conductor 225 through switch SI, conductor 234, switch G3, conductor 235, magnet H4 and conductor 236 to conductor cult from conductor 225 through limit switch LS3, conductor 244, switch H3, conductors 243 and 235, magnet H4 and conductor 236 to conductor 222 and keep magnet H4 energized when switch SI operates. will establish a circuit from conductor 222 through conductor 24I, switch HI, solenoid I04, switch H2 and conductor 242 to conductor 223, thereby energizing solenoid I04.

Connecting conductor 232 to conductor 225 establishes a circuit from conductor 225 through switch SI, conductor 232, magnet G4 and conductor 233 to conductor 222 and causes magnet G4 to be energized and operate switches GI, G2 and G3 to establish a circuit from conductor 222 through conductor 239, switch GI, solenoid 6I, switch G2 and conductor 240 to conductor 223, so that solenoid 6I is energized, and to establish a circuit from conductor 225 through switch LS2, conductor 238, switch G3, conductor 231 and 232, magnet G4 and conductor 233 to conductor 222 othat magnet G4 will not be deenergizedwhen switch SI is returned to its neutral position.

Deenergizing solenoid I03 and energizingrsolenoid I04 will cause solenoid I04 to shift valve plunger 90 of pilot valve 89 to the position shown in Fig; 10 and then liquid from gear pump M will flow through channel 42, valve 89 and channel 91 to chamber 61 and shift plunger 60' of control valve 61* to the position shown in. Fig. 15, thereby opening port I3 to port .14 so that enough liquid can escape from cylinders 8 through low pressure relief valve 8I to cause the pressure in cylinders 8 to drop to a value which is low enough to prevent pistons from moving pressure pad 5 upward when die 3 ascends but which is high enough to support pressure pad 5 in the position to which it was moved by die 3.

Deenergizing solenoid 60 and energizing solenoid 6I causes'solenoid 5| to shift plunger 41 of valve 46 to the position shown in Fig. 8 so that pump II is reversed as previously explained.

Liquid from pump II will then flow through channel I6, valve 6I channel I5 and check valve 11 to the lower end of cylinder 1 and cause piston 6 to raise die 3 and pressure will extend from channel-15" through channel 209 to right Closing switches HI and H2 As pressure pad 5 starts upward, switch SI'if a limit'switch will operate to disconnect-con-v ductors 232 and 234 from conductor 225 and to connect conductor 23I to conductor 225 but this has no effect until the press starts. another cycle of operation.

When pressure pad 5 reaches its upper limit, it

operates limit switch LS2 to disconnect conductor 238 from conductor 225 thereby deenergizing magnet G4. Deenergizing magnet G4 permits switches GI and G2 to open and deenergize solenoid 6| which permits spring 51 to shift plunger 41 of pump control valve 46 to its neutral position, thereby causing pump displacement to be reduced to zero in the previously described manner and the press to come to rest with the several parts thereof in the proper positions to start a second cycle of operation when starting switch 22I is closed.

While the invention has been shown embodied in vertical presses of the downward acting type, it is to be understood that the invention may be as readily embodied in other types of presses, that the terms used in the claims to denote direction are illustrative only and not limiting, and that the invention is susceptible of various modifications and adaptations without departing from the scope thereof.

therefrom during downward movement of said member, means for providing sufflcient resistance to the expulsion of liquid from said hydraulic means to cause a high pressure to be created therein and thereby enable said hydraulic means to resist downward movement of said member,.

means adapted when efiective to reduce the pressure in said hydraulic means to'a value which is low enough to prevent said hydraulic means from raising said member when said die starts end of valve casing 206 and shift valve 2I0 to the position shown in Fig. 4 so that piston 6 may expel liquid from the upper end of ram cylinder drain channel 55.

Solenoids 6I- and I04 are energized simultaneously but control valve 6! will shift and permit the pressure in cylinders 9 to drop to a low value before pump Il reverses and causes piston 6 to raise die 3 as previously explained.

When die 3 reaches its upper position, it operates limit switch LS3 to disconnect conductor 244 from conductor 225, thereby deenergizing magnet H4 which permits switche HI and H2 to open and deenergize solenoid I04.

Deenergizing solenoid I04 permits spring 39 to shift plunger 00o! pilot valve 89 to the neutral position shown in Fig. 4 so that chambers 01 and 88 are open to drain channel 55. Then spring 06 will shift plunger 53 of control valve 61 to the position shown in Fig. 4 to permit the liquid discharged by pump I I to flow through channel I6, valve 61", channel 18", check valves 83 and channels 65 to cylinders 3 and cause pistons 8 to raise pressure pad 3.

upward but which is high enough to support said member in the position to which it was moved by said die, and means responsive to said die reaching the end of its downward movement for rendering said last named means efi'ective before said die starts upward.

2. In a metal workingpress, the combination of a die, a pressure member arranged below said means having displacement" means arranged therein for supporting said member, said hydraulic means being adapted to have liquid expelled therefrom during downward movement of said member, a high pressure relief valve for resisting the expulsion of liquid from said hydraulic means to cause a high pressure to be created therein and thereby enable said hydraulic means means having displacement means arranged therein for supporting said member, said hydraulic means being adapted to have liquid ex-.

pelled therefrom during downward movement of said member, means for providing sufficient resistance to the expulsion of liquid from said hydraulic means to cause a high pressure to be created therein and thereby enable said hydraulic means to resist downward movement of said member, means adapted where effective to reduce the pressure in said hydraulic means to a value which is low enough to prevent said hydraulic means from-raising said member when said die starts upward but which is high enough to support said member in the position to which it was moved by said die, means responsive to said die reaching the end of its downward movement for rendering said last named means eiTective before said die starts upward, and means responsive to said die reaching a given point in its upward movement for directing liquid to said hydraulic means to cause it to raise said pressure member.

4. In a metal working press, the combination of a die, a pressure member arranged below said die and adapted to be moved downward thereby, hydraulic, means including liquid containing means having displacement means arranged therein for supporting said member, said hydraulic means being adapted to have liquid expelled therefrom during downward movement of said member, a high pressure relief valve for resisting the expulsion of liquid from said hydraulic means to cause a high pressure to be created therein and thereby enable said hydraulic means to resist downward movement of said member, a low pressure relief valve, means operable at the end of the downward movement of said die for connecting said hydraulic means to said low pressure valve before said die starts up-' ward to thereby reduce the pressure in said bydraulic means to a low value, and means responsive to said die reaching a given point in its upward movement for directing liquid to said hydraulic means to cause it to raise said pressure member.

' 5. In ametal working press, the combination of a die, a pressure member arranged below said die and adapted to be moved downward thereby, hydraulic means including liquid containing means having displacement means arranged therein for supporting said member, said hydraulic means being adapted to have liquid expelled therefrom during downward movement of said member, a high pressure relief valve for resistlng the expulsion of liquid from said hydraulic means to cause a high pressure to be created therein and thereby enable said hydraulic means to resist downward movement of said member, a low pressure relief valve, means including an element responsive to said die reaching a given point in its downward movement and an element responsive to pump pressure reaching a predetermined maximum for connecting said hydraulic means to said low pressure valve to thereby reduce the pressure in said hydraulic means to a low value, and means for rendering either one or the other of said elements effective. 6. In a metal working press, the combination of a die, a hydraulic motor for moving said die upward and downward, a pressure member a-rranged below said die and adapted to be moved means arranged therein for supporting said member, said hydraulic means being adapted to have liquid expelled therefrom during downward movement of said member, a high pressure relief valve for resisting the expulsion of liquid from said hydraulic means to cause a high pressure to be created therein and thereby enable said hydraulic means to resist downward movement of said member, a pump, fluid channels connecting said pump to said motor and said hydraulic means and forming therewith a hydraulic circuit, means for causing said pump to deliver liquid in a direction to cause said motor to move said die downward and thereby cause said member to be moved downward, a low pressure relief valve, means operable at the end of the downward movement of said die for first connecting said hydraulic means to said low pressure valve before said die starts upward to thereby reduce the pressure in said hydraulic means to a low value and for then causing reversal of the flow in said circuit to thereby cause said motor to move said die upward, and means responsive to said die reaching a given point in its upward movement for directing liquid from said pump said hydraulic means to cause it to raise said pressure member.

7. In a metal working press, the combination of a die, a hydraulic motor for moving said die upward and downward, a pressure member arranged below said die and adapted to be moved downward thereby, hydraulic means including liquid containing means having displacement means arranged therein for supporting said member, said hydraulic means being adapted to have liquid expelled therefrom during downward movement of said member, means for providing sufiicient resistance to the expulsion of liquid from said hydraulic means to cause a high pressure to be created therein and thereby enable said hydraulic means to resist downward movement of said member, a pump, fluid channels connecting said pump to said motor and said hydraulic means and forming therewith a hydraulic circuit, means for causing said pump to deliver liquid in a direction to cause said motor to move said die downward and thereby cause said member to be moved downward, means operable at the end of the downward movement of said die and before said die starts upward for first reducing the pressure in said hydraulic means to a value which is low enough to prevent said bydraulic means. from raising said member when i said die starts upward but which is high enough to support said member in the position to which it was moved by said die, and means responsive to the pressure in said hydraulic means being reduced to a low value for causing reversal of the flow in said circuit to thereby cause said motor to move said die upward.

8. In a metal working press, the combination of a die, a hydraulic motor for moving said die upward and downward, a pressure member arranged below said die and adapted to be moved downward thereby, hydraulic means including liquid containing means having displacement means arranged therein for supporting said member, said hydraulic means being adapted to have liquid expelled therefrom during downward movement of said member, means for providing suflicient resistance to the expulsion o! liquid from said hydraulic means to cause a high pressure to be created therein and thereby enable said hydraulic means to resist downward movement of said member, a pump, fluid channels connecting said pump to said motor and said hydraulic means and forming therewith a hydraulic circuit, means for causing said pump to deliver liquid in a direction to cause said motor to move said die downward and thereby cause said member to be moved downward, and means operable at the end of the downward movement of said die and before said die starts upward for first reducing the pressure in said hyldraulic means to a value which is low enough to prevent said hydraulic means from raising said memberwhen said die starts upward but which is high enough to support said member in the position to which it was moved by said die and for then causing reversal of the flow in said circuit to thereby cause said motor to move said die upward. a

9. In a metal working press, the combination of a'die, a hydraulic motor for moving said die upward-and downward, a pressure member arranged below said die and adapted to be moved downward thereby, hydraulic means including liquid containing means having displacement means arranged therein for supporting said member, said hydraulic means being adapted to have liquid expelled therefrom during downward movement of saidmember, a high pressure relief valve for resisting the expulsion of liquid from said hydraulic means to cause a high pressure to be created therein and thereby enable said hydraulic means to resist downward movement of said member, a pump, fluidchannels connecting said pump to said motor and said hydraulic means and forming therewith a hydraulic circuit, means for causing said pump to deliver liquid in a direction to cause said motorto mov said die downward and thereby cause said member to be moved downward, a low pressure relief valve, and means operable at the end of the downward movement of said die for first connecting said hydraulic means to said low pressure valve before said die starts upward to thereby reduce the pressure in said hydraulic means to a low value and for then causing reversal of the flow in said circuit to thereby cause said motor to move said die upward.

10. In a metal working press, the combination of a die, a hydraulic motor for moving said die upward and downward, a pressuremember, arranged below said die and adapted to be moved downward thereby, hydraulic means including liquid containing means having displacement means arranged therein for supporting said member, said hydraulic means being adapted to have liquid expelled therefrom during downward movement of said member, means for providing suflicient resistance to the expulsion of liquid from said hydraulic means to cause a high pressure to be created therein and thereby enable said hydraulic means to resist downward movement of said member, a. pump, fluid channels connecting said pump to said motor and said hydraulic means and forming therewith a hydraulic circuit, means for causing said pump to deliver liquid in a direction to cause said motor to move said die downward and thereby cause said member to be moved downward, means operable at the end of the downward movement of said die and before said die starts upward for first reducing the pressure in said hydraulic means to a value which is low enough to prevent said hydraulic means from raising said member when said die starts upward but which is high enough to support said member in the for directing liquid from said pump to said hydraulic meam to cause it to raise said pressure member.

11. In a metal working press, the combination of a die, a hydraulic motor for moving said die upward and downward, a pressure member arranged below said die and adapted to be moved downward thereby, hydraulic means including liquid containing means having displacement means arranged therein for supporting said member, said hydraulic means being adapted to have liquid expelled therefrom during downward movement of said member, a high pressure relief valve for resisting the expulsion of liquid from said hydraulic means to cause a high pressure to be created therein and thereby enable said hydraulic means to resist ownward movement of said member, a pump, fluid channels connecting said pump to said motor and said hydraulic means and forming therewith a hydraulic circuit, means for causing said pump to deliver liquid in a direction to cause said motor to move said die downward and thereby cause said member to be moved downward, a low pressure relief valve,- means operable at the end of the downward movement of saiiidie for first connecting said hydraulic means to said low pressure valve before said die starts upward to thereby reduce the pressure in said hydraulic means to a low value and for then causing reversal of the flow in said circuit to thereby cause said motor to move said die upward, means responsive to said die reaching a given point in its upward movement for directing liquid from said pump to said hydraulic means'to cause it to raise said pressure member, and means responsive to said member reaching a predetermined point in its upward movement for arresting the flow in said circuit to thereby stop said press.

12. In a metal working press, the combination of a die, a hydraulic motor for moving said die upward and downward, a pressure member arranged below said die and adapted to be moved downward thereby, a pump, means for directing liquid from said pump to said motor to cause it to move said die and said member downward, hydraulic means including liquid containing means having displacement means arranged therein for supporting said member, said hydraulic means being adapted to have liquid expelled therefrom during downward movement of said member and being of such capacity 'that liquid-is expelled therefrom at a rate in excess of the rate at which said pump delivers liquid to said motor, a high pressure relief valve, means for connecting said hydraulic means to said relief valve and to the intake of said pump simultaneously whereby the liquid expelled from said hydraulic means in excess of pump requirements is exhausted through said relief valve and said pump is supercharged at a pressure substantially equal to the resistance of said relief valve, and means operable at the end of the downward movement of said die for first reducing the pressure in said hydraulic means to a value which is low enough to'prevent said hydraulic means from raising said member when said die starts upward but which is high enough to support said member in the position to which it was moved by said die and for then reversing the delivery of liquid to said motor to 'cause it to move said die upward.

13. In a metal working press, the combination of a die, a hydraulic motor for moving said die upward and downward, a pressure member arranged below said die and adapted to be moved downward thereby, a pump, means for directing liquid from said pump to said motor to cause it to move said die and said member downward, hydraulic means including liquid containing means having displacement means arranged therein for supporting said member, said hydraulic means being adapted to have liquid expelled therefrom during downward movement of said member and being of such capacity that liquid is expelled therefrom at a rate in excess of the rate at which said pump delivers liquidtosaid motor, a high pressure relief valve, means for connecting said hydraulic means to said relief valve and to the intake of said pump simultaneously whereby the liquid expelled from said hydraulic means in excess of pump requirements is exhausted through said relief valve and said pump is supercharged at' a pressure substantially equalto the resistance of said relief valve, a low pressure relief valve, and means operable at the end of the downward movement of said die for first connecting said hydraulic means to said low pressure valve to thereby reduce the pressure in said hydraulic means to a low value and for then reversing the delivery of liquid to said motor to cause it to move said die upward.

14. In a metal working press, the combination of a die, a hydraulic motor for moving said die upward and downward, a pressure member arranged below said die and adapted to be moved downward thereby, a pump, means for directing liquid from said pump to said motor to cause it to move said die and said member downward, hydraulic means including liquid containing means having displacement means arranged therein for supporting said member, said hydraulic means being adapted to have liquid expelled therefrom during downward movement of said member and being of such capacity that liquid is expelled therefrom at a rate in excess of the rate at which said pump delivers liquid to said motor, a high pressure relief valve, means for connecting said hydraulic means to said relief valve and to the intake of said pump simultaneously whereby'the liquid expelled from said hydraulic means in excess of pump requirements is exhausted through said relief valve and said pump is supercharged at a pressure substantially equal to the resistance of said relief valve, a low pressure relief valve, means including an elementresponsive to said die reaching a given point in its downward movement and an element responsive to pump pressure reaching a predetermined maximum for connecting said hydraulic means to said low pressure valve to thereby reduce the pressure in said hydraulic means to a low value, and means for rendering either one or the other of said elements effective.

15. In a metal workingmress, the combination of a die, 'a-hydraulic motor for moving said die upward and downward, a pressure member arranged below said die and adapted to be moved downward thereby, a pump, means'for directing liquid from said pump to said motor to. cause it to move said die and said member downward, hydraulic means including liquid containing means having displacement means arranged therein for supporting said member, said hydraulic means being adapted to have liquid ex pelled therefrom during downward movement of said member and being of such capacity that liquid is expelled therefrom at a rate in excess of the rate at which said pump delivers liquid to said motor, a high pressure relief valve, means for connecting said hydraulic means to said relief valve and to the intake of said pump simultaneously whereby the liquid expelled from said hydraulic means in excess of pump requirements is exhausted through said relief valve and said pump is supercharged at a pressure substantially equal to the resistance of said relief valve, means operable at the end of the downward movement of said die for first reducing the pressure in said hydraulic means to a value which is low enough to prevent said hydraulic means from raising said member when said die starts upward but which is high enough to support said member in the position to which it was moved by said die and for then reversing the delivery of liquid to said motor to cause it to move said die upward, means responsive to said die reaching a given point in its upward movement for directing the flow of liquid from said pump to said hydraulic means to cause it to raise said member, and means responsive to said member being raised to a given point for arresting said flow of liquid.

16. In a metal working press, the combination of a die, a hydraulic motor for moving said die upward and downward, a pressure member arranged below said die and adapted to be moved downward thereby, a pump, means for directing liquid from said pump to said motor to cause it to move said die and said member downward, hydraulic means includin liquid containing means having displacement means arranged therein for supporting said member, said hydraulic means being adapted to have liquid expelled therefrom during downward movement of said member and being of such capacity that liquid is expelled therefrom at a rate in excess of the rate at which said pump delivers liquid to said motor, a high pressure relief valve, means for connecting said hydraulic means to said relief valve and to the intake of said pump simultaneously whereby the liquid expelled from said hydraulic means in excess of pump requirements is exhausted through said relief valve and said pump is supercharged at a pressure substantially equal to the resistance of said relief valve, a low pressur relief valve, means operable at the end of the downward movement of said die for first connecting said hydraulic means to said low pressure valve to thereby reduce the pressure in said hydraulic means to a low value and for then reversing the delivery of liquid to said motor to cause it to move said die upward, means responsive to said die reaching a given point in its upward movement for directing the flow of liquid from said pump to said hydraulic means to cause it to raise said member, and means responsive to said member being raised to a given point for arresting said flow of liquid.

1'7. In a metal working press, the combination of a die, a hydraulic motor for moving said die upward and downward, a pressure member arranged below said die and adapted to be moved downward thereby, a pump, means for directing liquid from said pump to said motor to cause it to move said die and said member downward, hydraulic means including liquid containing means

Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US2417794 *Nov 30, 1942Mar 18, 1947Verson Allsteel Press CoPunch press having a die cushion
US2444787 *Sep 20, 1944Jul 6, 1948Douglas Aircraft Co IncMachine for forming material
US2476870 *Nov 16, 1944Jul 19, 1949Breese Burners IncGeared rheostat control for oil burners
US2653562 *Sep 14, 1949Sep 29, 1953Automatic Elect LabAutomatic metal spinning apparatus
US2694567 *Dec 9, 1950Nov 16, 1954Baker Brothers IncMetalworking press
US2754786 *Jun 24, 1950Jul 17, 1956Glenn L Martin CoApparatus for controlled pressure forming of sheet material
US2766711 *Aug 9, 1950Oct 16, 1956Cincinnati Milling Machine CoPress
US4669298 *Sep 25, 1986Jun 2, 1987Amada Company, LimitedPress
US5499525 *Mar 25, 1993Mar 19, 1996Mannesmann Rexroth GmbhHydraulic drive for a sheet metal forming press
Classifications
U.S. Classification72/19.9, 72/453.13
International ClassificationB21J9/12
Cooperative ClassificationB21J9/12
European ClassificationB21J9/12