US2113110A - Hydraulically operated mechanical press - Google Patents

Description

April 5, 1938. w. ERNST ET AL HYDRAULICA LLY OPERATED MECHANICAL PRESS Filed May 29, 1934 4 Sheets-Sheet l i x/ 5 2 9 3/ M 2 as a M 4 44 0 0/ 3 4, 4 511?; M 8 5 Z 5 7 .2 3 7// m 4 \\r ,\\K\\\\. M 0 g w. 2 W. 6 W 8 w 4 m mmw nmmm MM; I. a

INVENTO/PS Warm [if/$7 004' c. Vault 51600.

ATTORNEYS April 5, 1938.

W. ERNST ET AL HYDRAULICALLY OPERATED MECHANICAL PRESS Filed May 29, 1934 ATTORNEYS 4 Sheets- Sheet 2 April 5,1938. w s ET AL 2,113,110

HYDRAULICALLY OPERATED MECHANICAL PRESS FiledMay 29, 1934 4 Sheets- Sheet 5- I "1/11/1111, '11, u I

' 004 c. you/mambo. 8y 0 4 Ap 5, 1938. w. ERNST ET AL HYDRAULI CALLY OPERATED MECHANICAL PRESS 4 sheet -sheet 4 Filed May 29, 1934 Patented Apr. 5, 1938 nYnnAUmoALLv PATENT OFFICE Walter Ernst and Don C. Youngblood, Mount Gilead, hio,-. assignors, by mesne assignments, w'rhe Hydraulic Press Corporation, Inc., Wilmington, Del; a'corporation' of Delaware Application May as ""934, Serial No. 728,134

.Thisinvention relates to presses, and, par ticular, to presses having hydraulic means to clamping the work pieces.

One object of our invention is to provides.

press having hydraulic means for clamping the work pieces, the pressure fluid therefor being provided by a piston-and-cylinder assembly connected to the platen of the press.

Another object is to provide a press whose platen may be. either hydraulically or mechanicallyoperated, wherein thework pieces are clamped by hydraulic means, this clamping action being intensified by additional hydraulic pressure supplied from a piston-and-cylinder assembly connected to and moving with the platen of the press.

Another object is to provide a press of the above nature, having a hydraulic clamping device wherein the major portion of the clamping mo- 00 tion is provided by a hydraulic ram operated by one source of pressure fluid, and wherein the final clamping action is intensified by additional pressure fluid supplied by a piston-andcylinder assembly connected to and movable with the press' platen, the second source of pressure fluid being independent of the first source.

Another object is to provide a press whose platen may be either hydraulically or mechanically operated, wherein the work pieces are clamped by hydraulic means, the pressure fluid for which is generated by means self-contained within the press and operated by the motion thereof rather than supplied from an outside source. In the drawings:

Figure 1 is a fruit elevation, partly in section, of one embodimentof the present our invention;

Figure 2 is a side elevation, partly in section,

of the press shown in Figure 1 with the reversing valve member in its neutral position to bypass the fluid.

Figure 3 is a longitudinal section through the reverse valve shown in Figure 2, with the valve member in its rearward position to cause an unclamping stroke to be'exerted; Figure 4 is a view similar toFigure 3, but with the reverse valve in its forward position to cause a clamping stroke to occur;

Figure 5 is a horizontal section taken along the line 55 of Figure 2, showing details of the clamp mechanism;

Figure 6 is a wiring diagram showing the electrical circuit for controlling the main hydraulic circuit of the press;

Figure '7 is a side elevation, partly in section,

- f the lower part of a press similarto that shown 11 Figure 2, but showing the clamping being perormed wholly'by the pressure fluid generated by he'motion of the press platen and lacking the 5 econdhydraulic circuit of Figure 2; d

Figure 8 is a side elevation of a portion of the {press shown in Figure 2, but with the reversal of the main pump accomplished by means of a solenoidally-operated reversing valve instead of 10 the servomotor-of Figure 2.

General construction of the press Referring to the drawings in detail, Figure 1 shows a press having a base I joined by side 15 members 2 to the top member 3. These members are connected by the strain rods 4, on which the nuts 5 have been threaded. Secured to the top member 3 is a bracket 6, on whichis mounted the main hydraulic pump I, which operates the 20 main hydraulic plunger 8, reciprocating in the cylinder l2. The plunger 8 is connected to the press platen 9, which reciprocates in guideways III on the side'members 2. In its reciprocation, it is retained in position between the retaining 25 members ll bolted to the side members 2 of the press. p

The platen '9 is provided with laterally, extending shoulders I3 oneach side thereof, as shown in Figure l, Extending upwardly from each 30 shoulder .13 is a piston rod I, having apiston head 15 attached thereto. The piston'head l5 reciprocates within a cylinder bore l6 inside the top member 3. -The end of the cylinder bore I6 is closed by the gland l1 adapted to compress the packing l8 and thus prevent leakage from the cylinder l6 around the piston rod H. A port 19 leads into the cylinder bore 16 and provides for the admission of pressure fluid thereto. The piston heads 15, when supplied with .pressure 46 fluid through the ports l9, serve as pull-back pistons, returning the platen 9 to itsupper'positibn when a pressing stroke has been completed. Also secured to the platen shoulders '13 and extending downwardly therefrom, are two addi- 45 tional pistons 20. The pistons 20 reciprocate in the cylinder bores 2|, access to which is given by the ports 22 and conduits 23 leading therefrom. The cylinderbore 2| is closed by a gland 24, which serves to, compress a packing 25 in 5 order to prevent leakage around the piston 20. The pistons 20 serve as pumps to provide a high pressure fluid for operating the clamping members of the press, as will appear later, and are, therefore, called the intensifier pistons 20. 55

The clamping mechanism oi. the press comprises a stationary clamp member 23 (Figure 2) and a movable clamping member 21 in opposition thereto. The stationary clamping member 231s securedflrmlyinarecesslinthe pressbase I. The clamping cylinder'block 23 (Figure 5) ,issecuredtothe pressbase I bymeansofthe horizontal strain rods 23and the nuts in threaded thereon.

cable along guideways 3I and is attached as by the bolts 32 to the clamping piston 33. The latter reciprocates in a cylinder bore- 33, provided with a gland is adapted to compress a packing detail. The reversing valve 43 is arranged to 33 and thus prevent leakage. The piston 33 is provided with an extended neck 31 and an extended head 33. 'The neck 31 is reciprocable,

within the bore 33, connecting the cylinderbore 34 with the cylinder bore 33, in which the extension piston head 33 is reciprocabie. From a port control the direction of the flow from the auxiliary hydraulic pump 41, so that the extension piston head 33 may be caused to move the clamping member 21 inward o'r outward as desired.

The reversing valve 43 is controlled by the hand lever 33 mounted upon one of the side members 2 of the press.

The reversing valve, generally designated ,43,

consists of a casing I33. Within. this casing reciprocates a valve member I, consisting of a neck portion Iii, having thereon the spaced heads I63, I31 and I33. The neck portion I3! 4 contains the bored passageway I33, interconnecting the chambers on opposite sides of the valve head I31. The valve casing I\33- on one'side is provided with ports III, III and I12, from which the conduit IIl leads to the auxiliary fluid tank III. From the port-I13, the conduit "III leads to the pressure side of the auxiliary hydraulic pump 41, whereas the conduit I13 leads from the suctio'n side thereof to the auxiliary fluid tank iii. On the opposite side of the valve casing I33, the

port I13 opens into the conduit 33, and the port I33 opens into the conduit 33.

The valve member I is connected to the connecting rod in, which is joined by the link in' to'the hand lever 43. Thus when the hand lever 33 is moved to and fro, the valve member I33 will be correspondingly shifted and the direction When the hand lever 33 is in the positionshown in Figure 2, the valve member IN is in its neutralposition. Under these conditions, the pressure fluid from the pump 31 through theport "3 into the valve casing I33, throughthe passageway I33 in the neck I33 and out through the port "I and the conduit I13, back to the auxiliary fluid tank I15. In this manner,

valve I is in its neutral ppsition.

If the hand lever 33 is now shifted to the left (Figure 2), the valve member I33 is shiited to the The movable clamping member 21 is reciproauauo right so that it occupies the forward position showninl'lgure4. Inthispositiompressure fluid flows through the port I13 and the passageway I33 0! the valve member I33, out through the port I33, along the conduit 33, through the port 43, into the space in front of the piston head 33 intheextensioncylinderbore. Thispressure causes the extension cylinder head 33 to move to the left, moving the clamping member 21 forwardly into engagement with the work piece. Meanwhile, the fluid displaced from behind the extension piston head 33 "move out through the port 32, the conduit 33, the port I I3 in the cylinder casing I33. he port "3, and the conduit I'll,

until It occupies the rearward"position shown.

in Figure 3. In this case, the pressure fluid flows from the pump 31, through the conduit I", the

port m, the port m, the conduit 44, and the port 32, into the space behind the extension piston head 33 in the cylinder bore 33. This causes the extension piston head 33 to move to the right, ca rying the clamping member 21 backward and unclamping the work piece. The fluid in the space in front of the piston head 33 escapes back to'the tank I" by way of the port 33, the conduit 33, the port I33, the port I12, and the conduit I ll.

v This clamping action is intensified by the action of the plungers 23 attached to and movable with the platen shoulders I3. As the plungers 23 move downwardly, the fluid within the cylinder bore 2Iiscausedtoattainahighpressurewhichis transmitted outwardly through the ports 22 (Figure 1), and the conduit 23 to the cylinder bore 33 by way of the port. This pressure fluid acts against the piston 33 and intensifies its clamping: action. Consequently, the intensi-.

fying pressure inceases as the pressing pressure increases, causing the work pieces to be held more tightly as the pressure rises. Thus the clamping pressure is made to bear a constant ratio to the pressing pressure.

mun control m The main pressing plunger], reciprocating in the cylinder I2, is caused to act by means of pressure fluid supplied by the main hydraulic pump I from the fluid tank I33 at the top of the press. The main hydraulic pump I is preferably 01' the variable delivery type, and its discharge may be controlled either by the provision of a reversing valve, such as the reversing valve 46, previously described, or by shifting the flow con- .troielement of the pmnp directly. In the form shown in Figure2, the main pump |.is provided with a servomotor I 33, having a piston-and-cylinderassembly' for moving the flow control element to and fro. The servomotor I3! is supplied with pressure fluid from an auxiliary pump (not shown), and its operation is controlled by means of the servomotor valve rod I35- Thus by moving the servomotor valve I35 in or out, the servo motor I33 may be caused to shift the flow controlring of the main pump 1 in opposite directions-and thus change the quantity and direction of the pressure fluid supplied by the main pump I. The details of this servomotor control system form no part of the pruent lnvention and will be the output of'the pump 411s by-passed while-the found disclosed in the United Statespatent. to Ernst, No. 1,861,116, dated May 31, 1932. when the platen 3 is to perform a pressing stroke, the' pressure fluid-from the main pump is supplied 75 to the main cylinder I2. When the platen 9 is to perform a return stroke, however, the pressure fluid from the pump 1 is supplied to the pullback cylinders I6, causing the pistons I5 thereof to raise the platen 9.

In the press of the present invention, the operation is regulated in several diflerent ways-.- either pressure-controlled or trolled" reversal with either semi-automatic or "completely-automatic operation. With pressure-controlled reversal, the platen moves downwardly until the pressure built up in the cylinder I2 reaches a predetermined amount, whereupon a switch is shifted, causing electrical devices to reverse the flow of the main pump I and thus reverse the direction of motion of the platen. With "position-controlled reversal, the platen moves downward until it trips a switch 9 I, whereby the same electrical devices again cause reversal of the platen.

With semi-automatic" operation, the platen moves downward, reverses itself when either the predetermined pressure ,or the predetermined position has been reached, moves upward to the beginning of its stroke and comes to rest. With "completely-automatic operation, the platen moves downward and reverses itself as before, but does not come to rest at the end of its upward stroke: instead, it again moves downward in a working stroke, again reverses itself at the attainment of the predetermined pressure or position, again moves upward, and goes on executing working strokes until halted by the operator.

The pressure switch 90 for regulating-the pressure-controlled operation is caused to operate byhaving its switch knob 93, engaged by the piston rod 94 of a piston head 95, which reclprocates within a cylinder 96 (Figure 1). The pressure 1' within the cylinder 96 causes the piston head 95 to move to the right, resisted by the force of the coil spring 91, asregulated by the threaded plug 99. By adjusting the latter, the force atwhich the piston rod 94 becomes operative to shift the switch 90 can be carefully adjusted. From the cylinder 96, the conduit I96 leads to the main cylinder I2, and serves to transmit pressure fluid between these two cylinders.

The position-control of the machine as to its upper and lower limits is regulated respectively by the movements of the push rods I3I and I03 respectively (Figure2). The push'rod I3I is reciprocably mounted in the lugs I30, mounted on the frame of thepress. Also mounted upon the press is a hand lever I5I', having a crank member I" adapted to engage the collars I49 and I49 on the push rod I3 I, and raise it upward or downward, as the hand lever I5I is shifted. The hand lever I5I is pivotally mounted on the stub shaft I81. The push rod I3I is also provided with a collar, I34 near its lower end, and adapted to limit its downward motion,

. A movable collar "Sis attached to the pushrod I3I and is adapted to be engaged by the movable sleeve I36 on the arm I3I, bolted to the platen shoulder I3. A collar I20 adjustably attached to the push rod I3I is adapted to engage the switch knob I2I of the electric switch I I1, and operate the same when the push rod I3I is lifted to a predetermined position, as when the platen 9 moves upward to its limit. This switch I" is used when completely-automatic operation is desired.

The shoulder I3 of theplaten 9 is also provided with an arm I38 secured thereto and having a .movable sleeve I39, surrounding the push rod position-conon the lug I. The upward motion of the push 5 rod I03 is regulated by the adjustable collar I45, engaging the lug I4I. a

A movable collar I40 is adjustably attached to the push rod I03 and is set at such a position that it is engaged by the movable sleeve I39 on the arm I30 of the platen shoulder I3, when the platen 9 moves downward to its lowest desired position. The push rod I03 is then caused to move downward, carrying with it the adjustable collar I02 attached thereto, and engaging the switch knob IOI of the lower limit reverse switch 9|. The operation of the latter switch 9I operates electrical devices, hereinafter described, in such a manner as to reverse the motion of the platen and cause it tomove upward;

The automatic shifting of the servomotor control valve'rod I65 is operated by the solenoid I56, having the armature I55 extending upwardly therefrom (Figure 2), and joined to the lever I52 by means of the link I53. The opposite end of the shaft I52 engagesthe adjustable collar I46 on the push rod I 3|. The push rod I3I is constantly urged in a downward'direction by means of the coil spring I32, acting between the movable crank m is connected by the link m to the crank I 94 mounted upon the stub shaft I95. The latter also carries the crank arm I96 connected by the link I91 to the servbmotor valve rocker arm I99, which is pivotally supported upon the floating link I99, mounted upon the housing of the servomotor I94 (Figure 2). Thus when the solenoid I56 is energized in the manner described later, the armature I55 moves downward, causing the crank I99 to move to the right. This motion is'transmitted through the bell crank I9I and the subsequent mechanism to the servomotor rocker arm I99, causing the servomotor control valve rod I85 to move inward to the right. When the solenoid I56 is de-energized, its armature I55 moves upward, causing the servomotor control valve rod I05 to move outward to the left, through the previously mentioned links and levers.

As shown in Figure 8, instead of the servo-. motorcontrol valve' rod I" being thus operated, by the solenoid I56, a reverse valve 200 forthe' pump I can be similarly operated, to reverse the direction and quantity of the pressure fluid being delivered by the main pump to the main piston 6. This'reverse valve may be of the same type'as the reverse valve 46 for the auxiliary pump 41, or any other suitable type of reverse valve may be used.

ing III having spaced ports with exhaust. lines 252, 255 and 255 leading therefrom to the oil tank I55. From another port the forward line 255 leads to the main cylinder I2. From another port the reverse line 255 leads to the pull-back cylinders I5. The pressure line 255 leads from the pump 251 to a middle port in the reverse valve casing 25I whereas the suction line 255 Ieads therefrom to the 011 tank I55.

The reverse valve casing 2" also contains a movable member consisting of a stem 2I5 having spaced heads 2, 2I2, and 2I5 thereon, together with a hollow passage 2I5 arranged in much the same manner as in the reversing valve previously described. .To this structure is attached the connecting rod 2I5 which is'pivotally joined to the lever I previously described. The mid-point of the lever I55 is pivotally mounted upon a bracket 2I5 attached to the frame of the press, and its opposite end is pivotallyattached to the link I5I. This link I5I is connected to the solenoid armature I55 in the manner previously described in connection with Figure 2.

Thus it will be obvious that when the solenoid I55 is energized in the manner described below, the armature I55 moves downward, transmitting this motion through the various links and levers to the reversing valve connecting rod 2I5. The latter is moved inward to the right, causing the pressure fluidto flow from the pressure line 255 into the valve casing'25I, through the stem bore 2 into the space between the heads 2I2 and 2I5, and thence to the main cylinder I2 by way of the forward" line 255. and the platen 5 then move downward under the influence of thispressure fluid.

When the main plunger motion is reversed in the manner described below, and the solenoid I55 is de-energized, the spring I52 retracts the armature I55 and causes the motion to be transmitted through the various links and levers to the reversing valve connecting rod 2I5, moving it outward to the left (Figure 8). When this occurs, the spaced heads 2, 2I2 and 2I5 move to the left, so that the pressure line 255 is connected to the reverse line 255, causing-the pull-back cylinders I5 to be charged with pressure fluid and to retract the main plunger 5.

Eflectrical'circait and operation thereof The electrical circuit whereby the solenoid I55 is energized to actuate the servomotor control valve rod I55 is shown in Figure 6. The circuit is principally controlled by the main magnetic switch, generally designated 55. This switch is kept normally open so that the switch arms 55 and 55 thereof areseparated from the contact points 5| and 52, to which the power current lines 55 and 55 are respectively attached, thereby breaking the circuit in the lines 51 and 55, leading from the switch arms 55 and 55 to the solenoid I55. In this situation the solenoid I55 is thus normally de-energized. The switch arms 55 and 55 are mounted upon the switch shaft 55, which is urged in the direction of the arrow by the spring anchored at one end to the hook 55, and at the other end to the crank arm 52 attached to the switch shaft 55. Also attached to theswitch shaft 55, as at I5, is the armature I2 of a holding coil II. On the opposite side of the switch shaft 55, the armature I2 is extended and provided witha contactor switch bar 15. The latterengages a pair of contact arms I5 and 15 when the arinature I2 is drawn into the "holding co'il II by the energisation thereof.

The main plunger 5 55 of which, the line 52 runs to the contact arm I5 of the main magnetic switch 55. From the opposite contact. arm I5 of the main magnetic switch 55, the line I I5 runs to the remaining pole of the push button starter switch II2. From the same contact arm 15 the line 55 runs to connect 'with the. power line 55, completing the circuit.

To start the operation and place the circuit in condition for further energization, the normallyopen push button starten switch H2 is closed. This energizes the holding coil II of the main switch 55, from the power line 55 through the holding coil II, the line 55, the manual switch III, the line I5, the push button starter switch 2, the line H5 and the line 55 to the power line 55. The energization of the holding coil II attracts the armature 12 thereof, rotating the switch shaft 55 in a directionopposite' to that 'of the arrow, and causing the contactor bar I5 to engage the switch arms I5 'and I5, thus bridging the circuit between them. The subsequent opening of the push bu ton starter switch II2, therefore, does not denergize the holding coil II, since this remains energized through the lines! 55 and 52, as described below.

Assuming the switch arms 55 and 55 of the double-throw switch 55 to be closed upon the contact points 55 and 5I, and the emergency push button reverse switch 55 to be closed, the circuit for keeping the holding coil II energized is completed from the power line 55 through the coil II, the line 55, the manual switch III, the line I5, the emergency push button reverse switch 55, the line 5I, the switch arm 54, the switch contact 55, the bar 52 of the normally-closed pressure-responsive switch 55, the switch point 51, the switch arm 55, the line 52, the contact arm I5, the contactor switch bar I5, the contact arm I5 and the line 55 to the power line 55. This causes the solenoid I55 to become energized when the contact arms 55. and 55 of the main magnetic switch 55 engage the contact points 5 I and 52 thereof. When this occurs, the solenoid I55 draws its armature I55 downward (Figure 2), this motion being transmitted through the subsequent levers and links to the servomctorcontrol valve rod I55, shifting the latter and causing the main pump I to deliver pressure fluid to the main cylinder I2. The main plunger 5 and theplaten 5 then move downward until the latter encounters the work piece. When the pressure increases in the main cylinder I2 by reason of the resistance encountered in forming the work piece, this pres.- sure is transmitted through the conduit I55 to the ;switch-operating cylinder 55 (Figure 1), where it II, and causes the switch arms 55 and 55 to become disengaged. from the switch points 5I and 52 (Figure 6) 'by reason of the action of. the

spring 55 upon-the arm 52 attached to the switch shaft 55. The solenoid I55 is thus de-energized by this breaking of the circuit in its lines 51 and 58. 'Ihe spring I82 (Figure 2) then drawsthe push rod I3I downward, and likewise moves the lever I52 by reason of the end thereof being engaged by the collars I45. The motion 01' the lever I52 is transmitted through the various levers and links I89 to I98 inclusive, drawing the servomotor control valve rod I85 outward to the left and thus reversing the flow of the main pump 1. When this occurs, the pressure fluid is connected through the ports I9 to the pull-back'cylinders I6, causing the piston heads I5 thereof to rise and raise the platen 8. Thus the press is made to reverse itself when a predetermined pressure is built up within the main cylinder I2 by the resistance encountered in forming the workpiece.

To reverse the press when the platen reaches a predetermined position, the switch arms 84 and 85 of the double-pole double-throw switch 83 are thrown downward into contact with the switch points 88 and 88 (Figure 6). It will be as-. sumed that the manual starting push .button switch II2 has been closed, thereby energizing the holdingcoil II of themain magnetic switch 58 through the lines I I3 and 58, as previously described. The press platen 9 moves downward as previously described, and the arm I88 attached to the platen shoulder I3 (Figure 2) likewise moves downward until its sleeve I38 encounters the collar I48. This causes the push rod I83 to be moved downward against the actionof the spring I43, until the collar I82 comes into engagement with the switch knob I8I of the normally-closed lower position reversing switch 9| (Figures 2 and 6). Prior to this opening of the switch 9|, the holding coil II had been kept energized from the power'line 56 through the line 68, the manual switch 18, the line I9, the

emergency reversing push button switch 88, the line 8|, the arm 84 of the double-poleswitch 82, the switch point 88, the switch bar I88 of the normally-closed switch 8|, the switch point 88, the arm 85 of the double-throw switch 88, the .line 82, the switch arm I5, the 'contactor switch bar I4, the switch arm 15, and the line 58, leading to the power line 55. The opening of the reversing switch I88 by the downward motion of the platen and the push rod I83 breaks the, circuit and de-energizes the holding coil II, thereby de-energizing the solenoid I55 in the manner previously described- This reverses the fluid flow by shifting the servomotor control valve rod I85 in the way described above.

For completely-automatic" operation, the circuit shown at the bottom of Figure 6 comes into use, the manual switch II5 being closed. To insure, an indefinite repetition of the working strokes, the n ain magnetic switch 58 must be reclosed in order to re-energize the solenoid I58 when the platen nears the top of its return stroke.

This is accomplished when the arm I81 on the,..

platen shoulder I3 lifts the collar I85 on the push rod 'I3I and causes the collar I 28 to trip the switch knob I2I of the normally-open upper reversing switch III (Figures 2 and 6). When the switch knob I 2| is thus tripped at the top of the return stroke or the platen8, the upper reversing switch I" closes, connecting the line I I6 to the line II'8 thereacross. The holding coil II of the main magnetic switch 58 then becomes energized trom the power line 55, through its own windings, thence through the line, the manual switch 18, the line Ill, the manual switch.

II5, the line H8, the upper reverse switch I,

the line 9, the line III, and the line 88 leading magnetic switch 58 immediately energizes the solenoid I55, which in tum'reverses the fluid discharge from the main pump I and causes the platen 9 to start another working stroke without any action on the part of the operator. As this occurs, the upper reversing switch I I! 'is released and opens the circuit when the push rod I3I is released by the platenarm I31, yet the holding coil 'II remains energized through the contactor switch bar I4, which bridges the circuit between the contact arms 15 and 16. When the platen reaches the bottom of its stroke, the reversal takes place in the manner previously described, and at the'end of the up-stroke the closing of the upper reversing switch I" again causes a working stroke to take place. In this manner, the press continues to operate and repeat its working strokes indefinitely until, the manual switch H5 is opened, whereupon the semi-automatic control again becomes operative.

It will be understood that we desire to comprehend within our'invention such modifications as may be necessary to adapt it to varying conditions and uses.

It will-be further understood that the second hydraulic circuit for operating'the double acting plunger 31-48 may be omitted, and the'enti're action thereof'performed by the pressure fluid generated by the. motion of the press platen. The lower portion of the press, arranged in this manner, is shown in. Figure '7. It has a piston I22 and a cylinder bore I28 in a cylinder block I24.

Having thus. fully described our invention, what we claim as new and desire to secure by Letters Patent is:

1. In combination in a press, a movable platen, means for moving the platen, a hydraulic piston operated by the motion of said platen, and clamping devices operated by the fluid from said hydraulic piston, said clamping devices including an auxiliary hydraulic piston for operating said clamping devices independently of said'platenoperated piston.

12. In-combination in a press, a movable platen, means for moving the platen, a hydraulic piston operated by the motion of said platen, an auxiliary clamping piston, and clamping devices operated partly by the fluid from said platen-operated piston and partly by said auxiliary piston.

, 8. In combination in a press, a movable platen, means for moving the platen, 'a hydraulic piston operated by the motionof said platen, an auxilmeans for moving the platen, a hydraulic piston operated by the motion of said platen, a clamping member, and a piston connected to said clamping member and operated by the pressure fluid from said platen-operated piston. 5. In combination in a press; a movable platen,

- means for moving the platen, a hydraulic piston operated by the motion of said, platen, a clamp- .ng member, a piston connected to said clamping 'nember and operated by the pressure .fluid from Laid platen-operated piston, and a second piston connected to said-clamping member and operated by pressure fluid independently of the pressure fluid from said platen-operated piston.

,6. In combination in a press, a movableplaten,

means for moving the platen, a hydraulic piston operated by the motion oi said platen, a clamping member, a piston connected to said member and operated by the pressure fluid from sure fluid independently of the pressure fluid from said platen-operatedpiston, said second clamping piston being adapted to move the clamping member into clamping position and said flrst clamping piston being adapted to intensify the clamping power of said second clamping piston.

8. In combination in a press, a movable platen, means for moving the platen, a hydraulic piston operated by the motion of said platen, a clamping member, a piston connected to said clamping member and operated by the pressure fluid from said platen-operated piston, a second clamping piston connected to and movable with said flrst clamping piston but actuated by pressure fluid independently of the pressure fluid from said platen-operated piston, said second clamp Diston being adapted to move the clamping member into clamping podtion and said flrst clamping piston being adapted to intensify the clamping" power of said second clamping piston, and means for reversing the motion of said second clamping piston 9. In combination in a press, a movable platen, Q

means for moving the platen, a hydraulic piston operated by the motion of said platen, a flxed her into clamping position, and means actuated by said platen-operated piston to intensify the clamping action of said clamping member moving means.

10. In combination in a press, a movable platen, means for moving the platen, a hydraulic piston'connected to and operated by said platen in its motion, a clamping member, and a piston rod connected to said clamping member, said piston rod having ,two independent piston heads operating in independent cylinders, one of said piston heads being actuated by pressure fluid from an 7 external source and the other piston head being rod having two independent piston heads operating in independent cylinders, one of said piston heads beingactuated by pressure fluid from an externalsourceandtheotherpistonheadbeing actuated by pressure fluid from said platen-operatedpismandmmns-forreversing the motion of oneof said pistonheads.

i2.In combination-in a movable platen, means for moving the platen, a hydraulic piston connected to and operated by said platen in its motion, a clamping member, a piston rod connected to said clamping member, said piston rod having two independent piston 'heads operating in independent cylinders, one of said piston heads being actuated by pressure fluid from an external source and the other piston head being actuated by pressure fluid from said platenoperated piston, and means for reversing the motion of one of said piston heads by reversing the flow direction .of the pressure fluid supplied thereto. a

13. In combination in a press, a movable platen, hydraulic means for moving said platen, a hydraulic piston connected to said platen tobe operated by the motion thereof, a flxed clamping member, a movable clamping member, means to move said movable clamping member into clamping.position, and means actuated by said platenoperatedpiston to intensify the clamping action of said clamping member moving means.

I be operated by the motion thereof, a flxed clamping member, a movable clamping member, means to move said movable clamping member into clamping position, means actuated by said platen- "operated piston to intensify the clamping action of said clamping member moving means, and means to reverse the motion of said platen when the pressure built up by the. resistance of the work piece exceeds a predetermined amount.

15. In combination in a press, a movable platen, hydraulic means for moving said platen, a hydraulic piston connected to said platen to be operated by the motion thereof, a fixed clamping member, a movable clamping member, means to movesaid movable clamping member into clamping position, means actuated by said-platen-operated piston to intensify the clamping action of said clamping member moving means, and means to reverse the motion of said platen when said platen reachm a predetermined position.

16. In combination in a. press, a movable platen, hydraulic means for moving said platen, a hydraulic pis'ton connected to said platen to be operated by the motion thereof, a fixed clamping member, a movable clamping member, means to move said movable. clamping member into clamping position, meansactuated by said platenoperated piston to intensify the clamping action of said clamping member moving means, and means to reverse the motion of said platen when said platen reaches predetermined positions near the ends of its working and return strokes. l'I.In combination in a press, a movable platen, hydraulic means for moving said platen, a hydraulic piston connected to said platen to be .operated by the motion thereof, a flxed clamping member-,1 movable clamping member, means to movesaid movable clamping member into clamping 'positiommeans actuated by said platen-oppiston to intensify the clamping action of said clamping member moving means, and

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