US2305610A - Press with die cushion - Google Patents

Description

Dec. 22, 1942. w. ERNST PRESS WITH DIE CUSHION Filed May a, 1940 4 Shee ts-Shee t 1 r s y WM 5 7P N m w W n r M 4 W w Dec. 22, 1942. w. ERNST PRESS WITH DIE CUSHION Filed May 5, 1940 4 Sheets-Sheet 2 I I fit 2 9b :1: P 39 1s.

a f 34 i 2 l I58 5] a2 3 I56 33 5 n55 a s 55 I s as e 9 u a as mom. a 7: L S u as Z2 2 B as F I u l80 f ZOI I .I all) I As M 5 b a ll/VE/VTO/i HAL m? [RA/S T Dec. 22, 1942. w, ERNST 2,305,610

PRESS WITH D2312 CUSHION Fiied May 1940 4 Shets-Sheet 3 Men/w? Wart? 56%;? 1

Dec. 22, 1942.

W. ERNST PRESS WITH DIE CUSHION Filed May 3, 1940 4 Sheets-Sheet 4 wol Patented Dec. 22, 1942 UNITED STATES PATENT OFFICE 2,395,610 ranss wrrn on: CUSHION Walter Ernst, Mount Gilead, Ohio, assignor to The Hydraulic Development Corp. 1110., Wilmington,'Del., a corporation of Delaware Application May 3, 1940, Serial No. 333,211

9 Claims.

The present invention relates to presses, and in particular to hydraulic presses with die cushion. It is an object of the invention to provide a press with a die cushion so as to allow operation of the press selectively with or without die I cushioning effect.

It is a further object of the invention to provide a press with a die cushion cylinder and elector which will allow operation of the press selectively with or without both the die cushion and the ejector. I

Another object of the invention consists in providing a press having a die cushion and an ejector, which press may be operated selectively.

with ejector but without die cushion, or with or without both the die cushion and ejector.

A still further object of the invention consists in providing a press with a die cushion and an ejector plunger in which the ejector plunger may,

the upper portion of the press illustrated in Figure 1.

' Figure 3 illustrates, likewise on a larger scale,

the lower portion 'of the press of Figure 1.

Figure 4 is a section along the line 4-4 of Figure 1.

Figures 5 and .6 show, diagrammatically, the

press during its downward or drawing stroke, and

Figures 7 and 8 show likewise, diagrammaticaliy,the press during its upward or return stroke.

The press as illustrated. in the drawings comprises a base I and a press head 2 connected with the base by strain rods 3, 3a, 3b and nuts I ing platen l4 when the arms abut the nuts i8. Connected with each clamping cylinder I0 is a hollow plunger I9 reciprocable in its respective auxiliary cylinder I, la and eifecting a communlcation between the respective cylinders l0 and I, la. I

The main cylinder 5 carries at its upper end a surge valve (see Figure 2). This surge valve is mounted within the surge tank or fluid reservoir 2| on top of the press head 2 and is of the type disclosed in the Ernst Patent 1,892,568 issued December 27, 1932. The surge valve 20 consists of a casing 22 bolted to or otherwise connected with the main cylinder 6. The casing 22 comprises .a longitudinal bore 23 and in alignment therewith a bore 24 of somewhatlarger diameter. The bore 24 is closed by a closure 25 having. an

aperture 26 therein. The closure 25 is engaged by one end of a spring 21, the other end of which I engages a valve disc 28 urged by the spring 21 against the valve seat 29, so as to close communication between the bores 24 and 23. The bore 24 communicates with the interior of the cylinder 6 through lateral bores 30. The valve disc 29 is adapted to be engaged by a plunger 3| reciprocably mounted in the bore 23 and carrying at its upper end a piston 32 urged by means of a spring 33 against the upper closure 34 of the casing 22..

The bore 23 communicates through bores 35 with the interior of the surge tank 2|. The upper closure 34 of the surge valve 20 has an aperture 36 therein adapted to eiTect communication be- 4, 4a and 5, 5a. The press-head 2 comprises a main cylinder 6 and auxiliary cylinders i, la. Reciprocably mounted in the main cylinder 6 is .a' drawing ram 3 supporting the press platen 3.-

Theplaten 9 carries clamping cylinders I closed at their ends by packing material Ii, compressed by glands l2. ing material ll of each clamping cylinder passes a clamping plunger |3 supporting a clamping platen l4. The clamping platen H has arms l5 (one only shown in the drawings) connected with Through the glands l2 and pack-- rods Ii passing through arms ll of the press platen and carrying at its upper end a nut ll tween the bore 23 and a conduit 31 comprising a relief valve 33 for releasing undue pressure in the conduit 37. i

A conduit 39 branches of! from the conduit 31 and leads by way of the conduit 40 to the cylinder bore 4| of the main cylinderrelief and pump lay-pass valve generally-designated as 42. This main cylinder relief and by-pass valve is disclosed and claimed in the Ernst Patent No. 1,956,758 issued May' 1, 1934, and provides for a drop in pressure within the upper part of the main cylinderi at the instant of reversal of the drawing ram 8. Such adrop in pressure is necessary before the surge valve disc 28 can be moved downwardly by the surge valve. plunger 3|. The valve 42 also takes care of the discharge of the variable delivery pump 43 during a fraction 0! a second which is required for the forcible opening 01' the surge valve 2| by the surge valve plunger 3|.

The main cylinder relief and by-pass valve 42 so as to cause the press platen 9 to lift the clamp cably mounted in the cylinder bore 4| of the the right and engaging with its other end thewall 56 of the valve 42.

The chamber 51 housing the spring 49 communicates with the tank 2| through an aperture 58, while the chamber 59 housing the spring 55 communicates with the tank 2| through an aperture 68. Apertures 6| and 62 in the valve 42 are adapted respectively to efiect communication of the cylinder bores 4| and 44 with the tank 2|.

The valve 42 furthermore comprises a channel 63 adapted to efiect communication between the cylinderbores M and 44. A conduit 4Ia leads from the bore 4| of the valve 42 to a conduit 65a, whichJeads on one hand through the port 29a to the upper portion of the main cylinder 6, while on the other hand it communicates with bores 68d and 69a of the connecting members 18a and Ho and the bore 13a passing through the strain rod 3a. The bore 13a then communi-,

cates through the bores a and 16a with a conduit 19a. A conduit 96 branches on from the conduit 4| a and comprises a relief valve 38a for relieving undue pressure in the conduits Ma and The cylinder bore 44 of the main relief and bypass valve 42 communicates through a conduit 64 with the conduit 65 leading to the port 66 of the variable delivery pump 43. The conduit 65 communicates through the port 66 with the upper portion of the main cylinder 6. The other port 61 of the pump 43 communicates through a conduit 61a with the bores 68 and 69 in the connecting members 18 and 1|, and a bore 13 through the strain rod 3.

The bore 13 communicates through bores 15 and 16 in connecting members 11 and 18 with conduits 19 and 88. The conduit 19 leads to a two-way valve, generally designated 8|, which comprises a cylinder 82 closed at its ends by packing material 83 and 84 compressed by glands A 85 and 86 respectively.

The cylinder 8| comprises 3 aligned bores, 81,

-. 88 and 89, having a diameter corresponding to the diameter of the pistons 98 and 9| connected with the push rod 92. The bores 81 and 88 are separated from each other by a chamber 93 having a larger diameter than the bores 81, 88 and 89 and communicating with a conduit 94. Similarly, the bores 88 and 89 are separated-from each other by a chamber 95 having a larger diameter than the piston 98 and communicating with a conduit I9 leading to the bores 15 and 16 in the connecting members 11 and 18.

The push rod 92 carries, adjustably mounted thereon, sleeves 91 and 98, each having a circular groove 99 and I88 respectively. The grooves 99 and I88 may be engaged by a pin IIII carried by an arm I82 supported by the press platen 9. The push rod 92 is guided in a sleeve I83, connected by means of arm-I84 with the press head 2.

Also connected with the press head 2 is a sleeve 1 I85 through which passes an adjusting rod I86 carrying at its upper end an adjustable collar I81 adapted to be engaged by a lever arm I88 of a lever I89. The lever. I89 is shiftably mounted on a stud H8 and is connected by means of its I switch in a tonnage control valve II9, which at the attainment of the predetermined pressure closes the circuit thereby energizing the solenoid I I4. The tonnage control valve I I9 is of the type disclosed in United States patent application to Ernst, Serial No. 214,772, filed June 20, 1938.

The adjusting rod I86 is provided with a thread I28 and carries an adjusting nut I2I adapted to be engaged by a collar I22 carried by an arm I23 connected with the press platen 9. The nut I2I is prevented from rotation by a pin or other guide means (not shown), so that a rotation of the rod I86 will cause the nut to move upwardly or downwardly in accordance with the direction of rotation of the rod I86. The adjusting rod I86 has an extension I24 connected by a gear system (not shown), with the handwheel I25 supported by the base I so that rotation of thehandwheel I25 causes an adjustment of the nut |2I relative to the thread I28.

The lever I89 is connected by a link I26 with a lever I21 adjustable about the stud I28 and connected by links I29 and I38 with a control rod I3I of the servo-motor I32 pertaining to the variable delivery pump 43 and adapted to control'the flow of fluid thereof. The control rod |3I is engaged by one end of a spring I33 having its other end connected to a. fixed point I34 and urging the control rod I3I toward the left so as to cause the variable delivery pump to deliver fluid through the conduit 61 a.

) The press head 2 supports a two-way valve I35 which in its construction corresponds to the two-way valve 8|. The two-way valve I35 comprises a cylinder I36 having threealigned bores I 31, I 38 and I39 having a diameter corresponding to the diameter of the pistons I48 and MI connected with a reciprocable push rod I42. The push rod I42 passes through packing material I,43 compressed by a gland I44 and carries adjustably mounted thereon collars I45 and I46. The collars I45 and I46 are respectively provided with grooves I41 and I48 cooperating with a pin I49 carried by an arm I58 supported by the press platen 9. The push rod I42 is guided in sleeves |5| and I52 connected with the press.

The bores I38 and I39 are separated from each other by a chamber I53 having a larger diameter than the pistons I48 and MI and communieating through a conduit I54 with a conduit I55 comprising check valves I56 and I51 which open in the direction of the arrows B and C. A conduit 156a leads from the conduit I55 into the auxiliary cylinder 1. The conduit I55 furthermore comprises a safety valve I53 which opens into the tank 2| when the pressure in the conduit I55 exceeds a predetermined value.

A conduit I59 comprising check valves I68 and I6I, opening in the direction of the arrows pertaining thereto, branches off from the conduit the drawings, only-relief valve I11 is shown com- I69 may, if desired, be continually held on its v valve seat by moving the rod I18 downwardly until its lower end, or a washerconnected therewith, abuts the ball I88 and presses it downwardly. This would prevent the oil in the tank from escaping through the conduit 39, in case some of the pipe connections, e. g. the members 18 or 1|, have to be removed for repairing or similar purposes.

The tank 2I further comprises a check valve;

I1I opening in the direction as indicated by the arrow pertaining thereto and adapted to effect communication between the conduit I12 and'the tank 2I. The conduit I12 communicates with a relief valve I13 and through conduits I14, I15 and H8 with the relief valves I11, I18 and I18. The said relief valves are all of the same structure so that description of one relief valve will be sufficient. 7

As will be seen from the drawings, the relief valve I11 comprises a casing 2I9 having reciprocably mounted therein a piston 228 connected with a piston rod 22I which is reciprocable in a bore 222 of a member 223 connected with the casing 2I9. The piston 228 is engaged by one end of a spring 224 which urges the piston 228 downwardly so that the piston rod 22I closes communication between the bore 222 communi- 'cating with the conduit I88 and the conduit 225 communicating with the conduit I13. The other end of the spring 224 is engaged by a washer 228 which is adjustable by means of the screw 221, so as to vary the thrust of the spring and thereby the pressure at which the relief valve will operate. Thescrew 221 is surrounded and protected from undue manipulation iy a, cap 228.

Each of the relief valves I13, I11, I18 and I19 communicates with- 'an auxiliary cylinder. In

municating through a conduit I 88 with the auxiliary cylinder 1a, whereas the auxiliary cylinder 1 communicates through the conduit I8I with the relief valve I18.

Connected with the press, platen 9' are push back plungers I82 which pass through glands I83 and packing material I84, compressed thereby, into pushback cylinders I85 which communicate with each other through conduits I88 and 88. The push back cylinders I88 are supported by the base I, which also carries a cushioning cylinder I81.

Reciprocably mounted in the cushioning cylinder I81 is a plunger I88 having a bore I88 therein. The plunger I88 carries an ejector I98 with elector members I8I passing through a plate I82 bolted to or otherwise connected with the base I. The plate I92 carries an adjustable stop I83 so as to determine the upper-most position of the ejector I98.

The bore I88 cooperates with a stationary provided a check valve 28I opening in the direction of the arrow'pertaining thereto. This check valve 28I allows the repair and removal of the conduit 288 without having to empty the tank 2I. Branching off from the conduit 288 is a conduit 282 receiving the leakage between the plunger I88 and the cylinder I81 and communicating with a safety valve 283, which in its turn,

. is adapted to communicate with a bore 284 convalve 288.

plunger I94 having a bore I88 therethrough. The

ceeds a predetermined value.

In the conduit 288 adjacent the tank 2| is The safety valve I89 is adapted bynected to the port 285 in the lower portion of the cushioning cylinder I81.

The bore 284 provided in the hollow arm 288 leads to a, port 281 in the die cushion check valve. generally designated 288. The check valve 288 comprises a valve member 289 having a piston 2I8 reciprocable in the bore 2 of the check The check valve 288 comprises a further bore 2I2 communicating with the conduit 18a and adapted also to communicate with the port 281 when the valve member 289 IS lifted from its valve seat 2I3. The upper portion of the valve 288 has threaded therein an adjusting rod 2 adjustable by rotation of the handwheel 2I5 so as to press the valve member 288 upon its seat 2I3.

The bore 2I2 in the 'valve 288 communicates through a conduit 2I6 with a chamber 2" of the die cushion relief valve 2I8. The construction of the valve 2I8 corresponds to the construction of the relief valve I11, so that a further description of the valve 2 I8 is not necessary. A conduit 229 leads from the bore 284 to the relief valve 2I8,and

the relief valve 2I8 is adapted to eiTect communication between the conduit 229 and the conduit 2I8. The relief valve 2I8 may be by-passed by a conduit 238 adapted to communicate with the conduit 229 and 2; through a straight way valve 23I.

A valve 282 corresponding in its construction to the valve 288 is provided in a conduit 233 communicating on one end with the conduit 84 and on the other end with the conduit 18. The valve 2 32opens in; the direction of the arrow D.

A further conduit 234 likewise communicating with the conduits 94 and 18 comprises a relief for instance by the operation of a push button. This causes energization of the solenoid II4 so that the armature II3 will be attracted and by means of the lever mechanism III, I28,

I3I moves the variable delivery pump 43 into position for delivering pr ssure fluid through the conduit 88. Pressure fluid now enters the upper portion of the main cylinder 8, and while the press ram slides down by gravity fills the space above the press ram 8 with fluid. This fluid is supplemented by fluid from the tank H which flows through the opening 35, the now opened surge valve 28 and the bores 38.

Pressure fluid through the conduit 85 also acts upon the piston 82 of the main cylinder relief and by-pass valve 42 and moves the valve member 5| toward the left against the thrust of the spring 55.

Liquid from the push back cylinder I85 may escape through the conduits 88 and I86, the bores 16, 15, 13, 1I and 68 and the conduit 61a to the suction side 61 of the variable delivery pump 43.

As soon as the ram 8 moves downwardly, therecation between the conduits 94 and 19.

The straight way valve I98 is supposed to be open while the straight way valve 23| is supposed to be closed.

When the clamping platen I4 approaches the workpiece, the pin I49 engages the grooves I41 of the collar I45 and while moving further downwardly moves the push rod I42 likewise downwardly so that at the time the press platen engages the workpiece the piston I48 has closed all communication between the conduits I54 and I64. Pressure now builds up in the main cylinder 6 and also in the clamping cylinders I8 and auxiliary cylinders 1, 1a. The pressure built up within the upper partof the main cylinder 6 closes the surge valve 28 by pressing its valve disc 28 against'its valve seat 29.

Undue pressure in the cylinders I8, 1, 1a is relieved through the corresponding relief valves I11, I18, I19, I13. Since the said relief valves are adjustable individually, different clamping pressures may be exerted in the different clamping cylinders. When the push rods 92 and I42 have been moved to their lowermost position by the pins IM and I49 respectively, the pins IM and I49 click out of their respective collars 98 and I45 and during the further downward movement of the push rods 92 and I42 slide over and beyond their respective collars 91 and I46.

While the press platen 9 with the die 236 connected therewith begins its drawing operation proper, the die 231 (see Figures 4 and 5) supported by the cushioning plunger I88 is gradually Y relieved through the safety valve I99 and the conduit 288 into the tank 2|.

As soon as the drawing operation is finished,

. or in other words, the ram 8 has reached its predetermined lowermost position, the pressure built up in the main cylinder 6 actuates the tonnage control valve II9 so as to disengage the switch connected therewith and to break the circuit comprising the solenoid I I4. As a result thereof, the

upper portion of the main cylinder 6, the retraction movement of the ram 8 is prevented for the fraction of a second. Fluid pressure in the conduit 61a is then conveyed through the conduits 39 and 48 to the piston 46 of the valve member 45 in the main cylinder relief and by-pass valve 42.

The pressure upon the piston 46 moves the valve member 45 with the piston 41 toward the left thereby establishing communication between the conduit Ma and the cylinder borev 4| and the aperture 6| in the valve 42, so that pressure fluid may escape from the upper portion of the cylinder able delivery pump 43 into the push back cylinders the bore 13a, the bore 68a into the conduit 65a,- a

and from there into the upper portion of the cylinder 6. If for some reason the relief valve 2I8 should not operate; or undue pressure should build up in the cushioning cylinder I81, the safety valve 283 will come into action and relieve undue pressure in the cushioning cylinder I81 through the conduits 282 and 288, into the tank 2|.

also acts as a cushioning cylinder. The excess pressure in the cushioning cylinder bore I89 is relieved through the conduit 94, the conduit 234, the relief valve 235 and the conduit 19, from where it flows through the bores 16, 15, 13, 69 and 68 to the suction side of the variable de livery pump 43; Any undue pressure maybe Pressure likewise builds up in the bore I89 which 6 through the port 29a the conduit Me the bore 4| and the aperture 6| into'the tank 2|.

The leftward movement of the piston 46 also establishes communication between the bore 4| and the channel 63, and since previously the piston 53 had moved toward the left, fluid may escape from the conduit 48 through the bore 4|, the

channel 63, thebore 44 and the aperture 62, into the fluid tank 2|. When a portion of the liquid above the ram 8 is thus released into the tank 2|, the pressure in the conduits 39 and 31 acting upon the piston 32 of the surge valve, presses the piston 32 downwardly and by means of the piston rod 3| moves thevalve disc 28 downwardly so as to establish communication between the fluid tank 2| and the upper portion of the main cylinder 6 through the bores 38 and 35.

Due to the pressure fluid delivered by the vari- I through the conduit 61a, the bores 68 and 69, 15, 16 and I86, the push back plungers I82 are gradually lifted so that the ram starts its actual retraction stroke.

. Since previously communication was cut oii between the conduits 94 and 19 through the valve 8|, and since furthermore the valve 232 is kept closed by the fluid pressure in conduit 19, the plunger I88 remains at its lower position during the initiation of the retraction stroke of the ram 8. However, when the clamping platen I4 has released the workpiece, the pin |8I engages the groove I88 of the collar 91 and, while the press platen 9 further moves upwardly, lifts the push rod 92 thereby moving the pistons 9| and 98 connected with the push rod 92 into their uppermost position. As a result thereof communication is effected between the conduits 94 and 19 through the two-way valve 8| so that pressure fluid passes from the conduit 19 through the two-way valve 8|, the conduit 94, the straight-way valve I98, the bore I95 in the plunger I94 and into the bore I89, thereby lifting the plunger I88 with the ejector I98 to eject the workpiece. While the plunger I 88 is moving upwardly, the valve member 289 opens due to the suction effect in the bore I84, and fluid from the upper portionoi the cylinder 6 passes through the conduit 65a, the bores 68a, 69a, 13a, 16, 19a, 2I2 and 204 into the cushioning cylinder I81. At about the same time, when the pin IOI engages the groove I of the collar 91, the pin I49 will engage the groove I48 of the collar I46 and by moving upwardly, will lift the push rod I42 with its pistons I40 and MI so as to establish communication between the conduits I54 and I64 through the two-way valve I35. This allows the pressure fluid in the auxiliary cylinders 1, 1a to escape through the conduits I56a, I55, I54 and I64 into the fluid tank 2|. When the ram approaches its uppermost position the collar I22 engages the nut'I2I on the threaded rod I06 and shifts by means of the collar I01, connected with the rod I06, the lever arm I08 so as to move the pump 43 into no-delivery position by means of the lever system I26 to I3I. The press is now ready for a further working stroke.

If full automatic operation of the press is desired, in other words if at the end of the retraction stroke the press shall automatically begin a new working stroke, it is merely necessary to provide the push rod I06 with contacting means which in the uppermost position of the rod I06 closes the circuit comprising the solenoid H4.

If it is desired to operate the press without both the die cushion and the ejector, the plunger To use the press with ejector but without die cushion, the handle 2I5 of the valve 208 is turned so as to release the valve piston 2I0, or in other words to unlock the valve 208. Furthermore, the valve 232 is to be unlocked and the straight-way valves 23l and I98 are to be opened.

The first part of the downward stroke of the ram 8 up to the time when the die 236 engages the workpiece, is the same as described in connection with the operation of the press when using both the die cushion and the ejector.

However, when the die 36 engages the workpiece andactually begins its drawing operation, no pressure will prevail in the bore I89 of the plunger I88 andin the cushioning cylinder I81, since the fluid expelled from the bore I89 during the drawing operation lifts the valve member in the valve 232, which valve member corresponds with the valve member 2I3 of the valve member 208, and escapes through the conduit 19, the

bores 13, 69 and the conduit 61a to the suction side of the variable delivery pump. The fluid ex- I88 is first moved downwardly either by the press platen 9 or by opening a drainage valve (not shown) provided in the'bottom of the cushioning cylinder I81 when the plunger I88 is in its lower position the handwheel 2I5 of the valve 208 is turned so as to press the valve member 209 by means of the locking rod 2I4 on its seat 2I3, thereby locking or closing the valve 208. Furthermore the valve 23I is to be opened while the valve I98 is to be closed.

With regard to the valve 232, which as previously mentioned, corresponds in its structure to the valve 208, it is immaterial in this instance whether it is locked or opened.

By closing the circuit comprising the solenoid II4, the working stroke of the ram 8 is initiated as previously described. However, when during the retraction stroke of the ram 8, after the through the port 205, the bore 204, the conduit 229, the straight-way valve 23I, the conduit 2I6 and the conduit 19a into the bore 15 from where it flows through the strain rod 3 and the conduit 6511 into the uppermost portion of the cylinder 6.

Consequently, there is no cushioning effect during operation of the press. The retraction stroke is initiated as previously described. When the clamping platen I4 has reclamping platen I4 has released the workpiece,, I the pin IOI engages the groove I 00 of the push rod 92 and shifts the pistons 9| and 90 to their uppermost position, no pressure fluid can enter cylinder I81. Consequently, the plunger I88 with the ejector I90 remains in its lower position.

The plunger I88 may at the end of the retraction stroke be lifted to its uppermost posi-.

tion, if desired, by unlocking the valve 208 and opening the straight-way valve I98. This would 'cause pressure fluid from the push back cylinders I85 to flow through the conduits 19 and 94 and the bore I95 into the bore I89 to lift the plunger I88 while fluid from the bores 68a, 69a, and 13a would pass through the conduit 19a the bore 2I2 and 20! into the push back plunger I81 to fill the space below the plunger I88. As a consequence of this movement, the ram 8 would sag somewhat, which would allow the spring I33 to move the variable delivery pump 43 into fluid delivery position to deliver fluid into the push back cylinders I85 to return the ram 8 into its uppermost position, whereupon the pump 43 as previously explained, will be again moved to no-delivqi'y position.

' come within the scope of the claims and the push back cylinders passes through the conduits I86 and 119 through the two-way valve 82. the conduit 94, the straight-way valve I98 and the bore I into the bore I 89, where it lifts the plunger I88 with the ejector I90. The space below the plunger I88 is filled with liquid from the conduit 19a through the valve 208, as previously explained.

The ejector thus ejects the workpiece.

' It will be understood that I desire to comprehend within my invention such modifications as the invention.

Having thus fully described my invention, what I claim as new and desire to secure by Letters Patent, is:

1. In combination in a press, a fluid operable pressing plunger, fluid supply means for'supplying fluid to said pressing plunger to operate the same, die cushioning means adapted to cooperate with said pressing plunger, relief valve-means associated with said die cushioning means for re- -li'eving pressure'therefrom when the pressure in said cushioning means exceeds a predetermined value; ejector means for ejecting aworkpiece after it has been drawn, a pair of check valves arranged in conduits communicating with said fluid supply means and respectively leading to said cushioning means and said ejecting means, controlling means for making said check valves inoperative, and a pair of shutoff valves respectively connected to said cushioning means and said ejecting means, said valves and said controlling means being adapted to control the operation of said cushioning means and ejector means so as to allow operation of the press selectively with ejector but without die cushion, or with or without both the die cushion and the ejector.

'2. In combination in a press, a main cylinder, a fluid operable drawing plunger reciprocable in ply means for supplying pressure fluid to said fluid chamber independently of the supply of fluid to said cushioning cylinder, controlling means for maintaining a predetermined pressure in said cushioning cylinder and valve means adaptedto by-pass said controlling means for connecting said cushioning cylinder with an exhaust without affecting'the pressure condition in said fluid chamber, whereby said cushioning plunger may selectively be operated during a pressing cycle as an ejector but without substantial cushioning effect.

3. In a press having a pressing plunger with fluid operable advancing and retracting means for reciprocating said plunger, a fluid operable die cushioning plunger reciprocable in a cushioning cylinder and provided with a fluid chamber, a piston adapted to be telescoped into said fluid chamber, said cushioning plunger being adapted to cause a cushioning effect during the pressing stroke and to act as ejector during the retraction stroke of said pressing plunger, adjustable relief valve means responsive to a predetermined pressure in said cushioning cylinder for relieving pressure therefrom, a check valve interposed between said advancing means and said cushioning cylinder and being adapted in response to. a retraction stroke of said pressing plunger to allow passage of fluid therethrough from said pressing plunger to said cushioning cylinder but not vice versa, locking means for preventing the flow of fluid through said check valve in either direction, a first shutoff valve adapted to by-pass said check valve, and a second shutofl valve interposed between said fluid chamber and said retracting means for selectively establishing or interrupting communication between said fluid chamber and said retracting means, said locking means and said shutoff valves being operable selectively to allow operation of the press with or without cushioning effect and actuation of-said ejector.

4. In a press having a pressing plunger with fluid operable advancing and retracting means for reciprocating said plunger, fluid operable combined die cushioning and ejecting means, fluid supply means for supplying fluid to said plunger reciprocating means and said cushioning and ejecting means to actuate the same, control valve means responsive to the travel of said pressing plunger for interrupting hydraulic communication between said fluid supply means and said die cushioning means at a predetermined point of the working stroke of said plunger, and for effecting communication between said ejecting means and said fluid supply means at a predetermined point of the retraction stroke of said plunger, a check valve arranged to allow fluid to flow from said retracting means to said ejecting means irrespective of the position of said control valve means, locking means associated with.

said check valve to lock the same in closed position, to prevent said last mentioned flow, a pressure relief valve hydraulically connected with an exhaust and said cushioning means, and a shutoff valve for by-passing said relief valve, whereby said shutoff valve is adapted in cooperation with said check valve selectively to allow operation of said ejecting means with or without actuation of said cushioning means.

5. In combination in a press, a main cylinder, a press ram reciprocable in said main cylinder to perform a pressing and a retraction stroke, fluid supply means for supplying fluid to said main cylinder to actuate said ram, a die cushioning cylinder-piston-assembly with a fluid operable member acting as ejector during the retraction stroke of said ram, relief valve means for relieving pressure fluid from said cushioning cylinderpiston-assembly in excess of a predetermined pressure, a check valve for by-passing said relief valve means to allow free escape of fluid from said cushioning cylinder-piston-assembly during the pressing stroke of said press ram, thereby preventing said member from acting as cushioning member, and locking means associated with said check valve for selectively locking the same in closed position to prevent said free escape, thereby selectively causing said member during one and the same cycle to act as ejector only or to exert a cushioning effectand subsequently to act as ejector.

6. In combination in a press, a reciprocable press ram, means for supplying fluid to said ram to actuate the same, a fluid operable plunger operable as ejector for ejecting a work piece during the retraction stroke of said ram and also operable selectively as cushioning means during the advancing stroke of said ram, controlling means responsive to the movement of said ram for controlling the flow of fluid to and from said plunger, a check valve 'for allowing free escape of fluid from said plunger, locking means for making said check valve 'inefiective to prevent said free escape, and means responsive to a predetermined pressure acting on said plunger for releasing pressure therefrom in excess of said predetermined pressure.

7. In combination in a press, a reciprocable ram, means for supplying fluid to said ram for actuating the same, a fluid operable plunger operable selectively as cushioning means during the pressing stroke of said ram and as ejector for ejecting a work piece during the retraction stroke of said ram, a pressure relief valve for relieving pressure from said plunger in excess of a predetermined pressure acting thereupon, control valve means movable in response to the travel of said ram from a first position into a second position said plunger, said shutoif valve being movable selectively into closing position for making said plunger ineffective as ejector and cushioning plunger.

. 8. In combination in a press, a main cylinder,

a fluid operable press plunger reciprocable in said cylinder, a die cushioning cylinder-piston assembly, an ejector cylinder-piston-assembly, one element of said cushioning cylinder-piston-assembly and of said ejector cylinder-piston-assembly being stationary and the respective cooperating element-s of said cushioning and ejector cylinderpiston-assemblies being movably connected with each other, a fluid source for supplying fluid to said die cushioning cylinder-piston-assembly,

pressure fluid supply .means for supplying pressure fluid to said ejector cylinder-piston-assembly independently of the supply of fluid to said cushioning cylinder-piston-assembly, control in said cushioning cylinder-piston-assembly, and valve means adapted to by-pass said control means for connecting said cushioning cylinder-l piston-assembly with an exhaust without affect- I i 7 admitting pressure fluid to said auxiliary area in response to a predetermined travel of said". ram

during the retraction stroke thereof to operate said member as ejector, check valve means remeans for maintaining a predetermined pressure 5 sponsive to the ejecting movement oi said memher to admit fluidto said main area, valve means normally in position to allow'free escape of fluid at substantially-no pressure from said main and auxiliary areas during the pressing stroke of said ing the pressure condition in said ejector cylin- 104 ram, thereby preventing said member from actder-piston-assembly, wherebysaid movable element of said cushioning cylinder-piston-assembly may selectively be reciprocated during a working cycle without substantial cushioning eflect irrespective of the operation of said movable element 15 plunger, and means for relieving pressure from said plunger in excess of a predetermined pressure acting thereupon, thereby allowing operaof said ejector cylinder-piston-assembly as ejector during the said cycle.

9. In combination in a press, a main cylinder, a fluid operable press ram reciprocable in said main cylinder to perform a pressing and a retrac- 20 plunger and ejector.

tion stroke, a fluid operable member with a main area and an auxiliary area,- control means for ing as cushioning plunger, means associated with said valve means for holding the latter in closed position during a complete cycle of said ram for preventing saidfree escape of fluid from said tion of said plunger during one andithe same cycle selectively as ejector only, or as cushioning WALTER mm. Y

Images