US2316471A - Full automatic press control - Google Patents

Description

April 13, 1943.; wm. TUCKER 2,316,471

. f FULL AToMATIvc-PRESS CONTROL Fild March 15`, l1940 2 sheets-sheet 1 Alpril 13, 194s. W. R. TUCKER 2,316,471

FULL AUTOMATIC-PRESS CONTROL Filed March 15, 1940a 2 Sheets-Sheet' 2 lthe press ram is Patentsdnpr.. 13, i943 FULL AUToMA'ric Parzss CONTROL Warren R. Tucker, Dayton, Ohio, assignor to The Hydraulic Development Corporation, Inc., Wilmington, Del., a corporation of Delaware Application March 15, 1940, Serial No. 324,155

' (ci. io-52) .12 Claims.

This invention relates to hydraulic presses, and in particular to hydraulic presses in which at the end of the working stroke the return movement of the press ram is automatically effected. In presses of the above-mentioned type, the return stroke of the press ram was heretofore generally initiated by the intervention. of electric controlling'nieans.

It is an object of the present invention to provide il. press of the type referred to above in which the electric controlling means for initiating the return stroke of the, ram are replaced by hydraulic means. ,Y

VIt is another object of the invention to provide a hydraulic press in which the return strokeY of means. l

Another object of the invention consists in press piston 2 connected with the ram Sand i lthe press platen 4. The-lower end of the kpress cylinder I is closed by means of packing material initiated by pure hydraulic,

providing a press with hydraulic control means for the operation of the press ram-which hydraulic control means are operable so as selectively to eect semi-automaticA or full automatic operation of the press. Still another object of the invention consists in the provision of a press in which the press' platen at the'end of its working stroke operates hydraulic means which initiate the return movement of the press platen. 1

It is a further object of the invention to provide Aa hydraulic press inl which pressure responsive means are provided for the actuation of -hydraulic control means which, in its turn, initiates the return movement o fthe press platen. f

A still further object of the invention consists in the provision of` a press,A having a reversible variable delivery pump for supplying uid to the press cylinder, with vhydraulically operable valve means which, in cooperation with a pilot pump, automatically cause a reversal of the variabie delivery pump whenthe press ram has `reached a predetermined position. l

These and other objects and advantages of the present invention will appear more clearly '.irom. the following description in connection with the accompanying drawings, inwhich:Y

Figure 1 illustrates an embodiment of thepress according to the present invention in its idle ,j position 3 Figure 2 is a view similar to that'oi Figure 1 illustrating the press during the downward movement of the pressl platen;

Figure 3 illustrates the press of Figure 1 at the beginning of the upward movement of th press platen; and

5 compressed by a gland 6. The upper portion of the press cylinder I is provided with a ilange l supporting'a surge tank or uid reservoir 8, the interior of which is adapted to communicate with the interior of the press cylinder i by means of a surge valve generally designated 9. 'I'he surge valve 9, which is of the type disclosed in the ErnstPatent No. 1,892,568, issued December 27, 1932, is bolted or otherwise connected with the .pressv cylinder I and comprises an upper portion Ill arranged in the tank 8, and a lower portion or sleeve II inserted in the press cylinder -I. vThe sleeve II has a cylinder bore I2, communicating through bores I3 with the interior of the tank 8, and'a cylinder bore i4 -oiV a. somewhat larger diameter, adapted to communicate withtheinterior of the lpress cylinder i through openings I5 provided in the sleeve II.r Reciprocably mountedr inthe surge, valve bore Id is ak cup-shaped plunger I6 adapted to .open or close the openings I5. The lowerend of the surge valve bore I4 is closed by a closure I'I having an opening I8 therein for allowing pressure iiuid above the piston 2 to act on the plunger I5. A spring I9 engages with its lower end the closure" Il, while the upperl end of the spring Iii-engages the cup-shaped plunger I6 and urges the same upward into a position where it abuts the shoulder on seat 12a and closes the openings I5. The coil spring I9, however, exerts a verylight tension, merely suicient toovercome the forces of gravity, -'and enabling the valve plunger I6 to be drawn downwardly lin response to suction in the top of the press cylinder I and to draw fluid through the bores I 3,v the sleeve II and openings I5 into the press cylinder I. The upper portion I0 of the surge valve 9 comprises a cylinder 'bore vIllaV communicating -through a passage 2Il with the bore I2 of the spring 23 urging the piston 2I continuously up# ward. The upper portion of the cylinder vI6 is closed bya cylinder head 24 having an opening stroke of they press piston 2 as the latter coasts downwardly under the influence of gravity. 'I'he surge valve 8 closes ,automatically against the surge valve seat |2a when the platen 4 has engaged the workpiece, and this due to the fact that the pressure built up within the upperjpart of the press cylinder I urges the surge valve plunger I8 upwardly, aided by the force of the spring I8. When the platen 4 is on its return stroke, the piston rod 22 forcibly holds open the surge valve plunger I 8 so as to enable the escape of uid'from the upper portion of the cylinder I through the surge valve into the tank 8.

The valve 28 is provided for releasing the pressure in the upper portion of the press cylinder I at the beginning of the return stroke of the same strength so that the now-control member 50 will be held in its intermediate or no-delivery position when the pressure acting` upon both plungers 54 and 51 is the same. The interior of the hollow arm 5| communicates with a conduit 8| leading to the bore 82 of a four-way valve. Similarly, a conduit 84 connects the interior of the hollow arm 52 with the bore 52 of the fourway valve 83. Y

Reciprocably mounted in the cylinder bore 82 is a valve member 85 with two'pistons 88 and 81 Y, adapted respectively to open' or close the communication of the bore 82 with the conduits 84 and 8|'. The valve member 85 is connected by means of .a connecting rod 88 with a piston 89 and by means of a connecting rod 10 with a piston 1|. The pistons 88 and 1| are reciprocably mounted in uid'cylinders 12 and 13 respectively, which are'separated from the cylinder bore 82 by partitions 14 and 15. i The uid cylinder 12 communicatesv by means of a conduit. 18 with a cylinder bore 11 of a three-way valve 18, which ram 3. This valve 28 comprises two spring A chambers 29 and 30 with spring 28a and 30a respectively, and two cylinder bores 3| and32. The cylinder bore 3| is adapted to communicate through an aperture 33 with the surge .tank 8, and similarly an aperture 34 is provided for ef'- fecting communication between the cylinder bore 32 and the tank 8. Furthermore, a channel 35 is provided in the valve 28 for effecting communied in the bore 32 ofthe valve 28 and is urged toi ward the. right by the spring a. The piston 4| is adapted to close oil! the communication between `the channel 35 and the cylinderA bore 32. The valve 28 comprises a bore 43 which is adapted to communicate with the bore 3| and is continuously connected with a conduit 44. The conduit 44 communicates by means of a `conduit. 45 with thecylinder bore 32 andleads to a conduit 46 connected with the-port 41 of the variable delivery pump 48. A conduit 58 branches off from the conduit B4 and comprises a relief valve 88 which, at a predetermined pressure in thev conduit 48 eiects communication of said conduit with the surge tank.

The variable delivery pump 48 comprises a pump'casing 4 8 housing a shiftable now-'control member 50 which, in its turn, is adapted to vary the position of a secondarylrotor, not shown, for varying the delivery of the pump. The arrangement of the secondary rotor in cooperation with radiall pump pistons is well-known to those skilled in the art and for a more detailed description thereof, reference may be had to U..S. Patents Nos. 1,964,244 and 2,041,172.

Connected to each side ofA the pump casing 48 are hollow arms 5| and 52 respectively. The hol- -the cylinder bore 82 of the four-way valve 83. The other end of the cylinder bore 82 is likewise connected with the conduit 82. by means of the conduit 83. A further conduit 80a is adapted to eiect communication between thecylinder bore 82 and the conduit 80.

Reciprocably mounted in the cylinder bore 11 of the three-way valve 18 is a valve member 84 with two pistons 85l and 88 adapted alternately to close oi the communication between the cylinder 11 and the conduits 80 and 8| respectively.

"The valve member 84 is connected by means of a rod 81 with a piston 88 reciprocably mounted in l a cylinder bore 88 separated from the cylinder bore 11 by a partition 80. A spring 8| is provided between the partition 80 and the piston 88 and urges the piston 88 toward the right. The cylinder bore 88 communicates, adjacent the partition 30, with the outside by means of a breather opening 92. The other end of the cylinder bore 88 vcommunicates through a conduit 83 with the Ito the suction side of the pilot pump 18, while the other arm of the conduit |00 leads to the conduit 80. The last-mentioned arm comprises a relief valve |02. A conduit |03 leads from the cylinder bore 85 into a conduit |04, one end of which is connected with the cylinder bore 13 of the four-way valve 83, whereas the other end of the conduit |04 leads to a bore |05 of a valve,

low arm 5| houses a spring 53 acting upon a plunger 54 connected with a push rod 55 so as to urge the push rod 85, and thereby the flow-control member 50 toward the left. Similarly, the

o hollow arm 52,- houses a spring 58urging a pun'ti with a pusnroa u toward the nent. Both springs 53 and 58 have substantiallythe f duit 80.

` breather openings vided with a pin adapted to cooperate with a bayonet slot ||2 so as to hold the shift rod |09 in its left-hand .position against the thrusty of spring |09a. As will b e clear frornJthe drawing.

the conduits |03 and 99 communicate with each other when the shift rod |09 is in its right-hand position, whereas the communication between the said twoconduits is broken when the y, shift rod |09 is moved to its left-hand position.

'I'he conduit 99 communicates by means of a conduit ||3 with the cylinder bore |05 of the f valve |06. Reciprocably mounted in the cylinder bore is a valve member ||4 -with twoipistons" conduit |26, the bore los, the conduits lot-and 2m, meter@ saand the conduits 9s, m and' |0| back to the suction side of the pump y19. If

||5 and H0, bf which the piston ||5 is connected with a follower am ||1 carrying a follower H0. 'I'he piston ||6 is connected with a piston rodl im passing through apartition which separates the bore |05 from a spring chamber 2| in the valve |06. The spring chamber |2| comprises a spring |22`which engages a piston |23 connected with the piston rod ||9 sp as to urge the valve member ||4 toward the left. The spring chamber |2| is provided with breather openings |24, and a similar breather opening |25 is provided between the left-hand Wall of the cylinder |06 Gil and the piston ||,5. The cylinder bore |05 of the valve |06 is adapted to communicate by` means of the conduit |04 with the bore 13 oil the valve 63. A further conduit |23 leads from the cylinder bore |05 of the valve |06 to the con- The lower portion o'f the press cylinder communicates by means of a conduit |21 with the port |28 of the pump V46. A conduit |29 branches off from the conduit |21 and leads to the conduit 25 and to a c onduit |30 comprising a relief valve |3| and adapted to release excessive fluid prossure in the conduit |30 into the tank 8. A further check valve |32 is adapted by means of a conduit |33 to admit fluid from the tank 8 into the conduit |29.

The press` platen d is provided with an arm |34 adapted to engage a collar |35 adjustably connected* with a reciprocable control rod |36 carrying at its upper end a cam |31 adapted to cooperate with the -follower ||6 for actuating the valve member |14. The control rod |36 is reciprocably mounted in guides (not shown) connected with the press. f i

.The valve 16 together with the conduit 93 leading from the valve bore 89 to the conduit 46 may be replacedby the structure illustrated in Figure 4. the control rod |36 is provided with two collars |36 and |39 adjustably connected with the rod |36. The collar|36is adapted to'be engaged by the arm |34 of the press platen 4 during its downward movement, whereas the collar |99 is adapted to engage the arm |40 of a bell crank lever, generally designated |4|. lever ,Ml is shiftably 'mounted aboutA a stud |42 and is operatively connected by means of its arm |63, a link |44, and a push rod with a piston |46 of a valve member |41. The valve member- |41, which corresponds to the valveb member 84 of the valve 18, comprisesa second' piston |46. The pistons |46 and |46 are reciprocably mounted in the cylinder bore |49 of the valve casing 18a, which bore, in its turn, is adapted to communicate with the conduits 60, 16 and 8|. Adjacent each end of the cylinder bore |49 The piston |48 ls connected with a piston rod |52 passing through the right-hand end wall of thevalve casing19a and carrying an abutment The bell crank.

now, a working stroke of the 'press `is to be performed, the operator moves the control rod |03- I toward the left, thereby interrupting the communication between the conduits |03 and 99. Asi a result thereof, pressure builds up in the .conduit |04 which is conveyed `intothe bore 'I3 ,of the valve 63 and acting upon the piston 1.1,. i

moves the valve member 65 toward the left. This; movement of Ithe valve member 65 establishes-communication between the conduits 00a.

and 64 so that :duid pressure delivered by the pilot pump 119 acts through the conduits 30, 80a, the bore 62 and the conduit 64 upon the piston 51 ofbthepump arm 52, thereby moving the flowcontrol member toward the right.

The control mechanismJthen occupies the position shown in Figure l2. In this position the pump 48 delivers pressure fluid through the conduit 46 into the upper portion ofA the cylinder while the` ram 3 moves downwardly by gravity.

The llluid deliveredby the pump 48 is supplemented by uid from thetank 8 which passes Y to the Aport |29 of the pump 48. The pressure `fiuid delivered by the pilot pump k19. passes According to the structure of Fig. 4,

|50 and |5| are provided. g

through the relief valve |02 land the conduits |00 andv |0|, back to the suction side of the pilot pump 19. As soon as the platen 4 engages the workpiece to be drawn, pressure builds up in the upper portion of the cylinder and the conduit 46 and acts through the conduit 44 and the conduit 45 upon the piston 32 in the valve 26, thereby moving the valve member 40 toward the-left against the thrust of the spring 30. If accidentally the pressure in the vconduit 46 should become too high, it is relievedthrough the conduits 44 and 59 and through the relief valve into the tank 8. At the same time the pressure above the piston 2 causes the plunger left. This leftward movement of the valve member 84 establishes communication between 4the -conduit 80 and the conduit 16 so that pressure fluid delivered by the pilot pump 19 now passes through the conduit 80, the bore 11, the conduit 16 into the cylinder 12 of the valve 63, where it acts upon the piston 69 and moves the valve member toward the right. This movement of the valve member 65 establishes communication `between the conduit 80a and conduit 6| so that iluid pressure from the pilot pump 19 now passes through the conduits and 80a, thev cylinder bore the tk s througnthe bore sz, the conduits a2, ....ls and Inn.

52, and the conduit BI into the right-hand pump arm Il where it acts upon the piston, 54 and moves the now-control member 50 toward the left. This causes a reversal of the pump and fluid l pressure of the pump is now delivered through the conduit |21 into the lower portion of the press cylinder I (Fig. 3).

Since previously when pressure was built up in the upper portion of the cylinder I, the plunger I5 had closed the apertures I5 of the surge valve 3, no uid can escape from the upper portion oi.

the cylinder I through the surge valve. The iluid pressure in the conduit |21 is therefore conveyed through the conduits` |29 and 26 into the bore 3| of the valve 28 where it acts upn the piston 38 and moves the valvemember 36 toward the left. Since the piston. v32 previously wasl moved toward the left, fluid may escape from the conduit |21, through the conduit- |29, the con-v duit 25, the channel 35, the bore 32 and the aperture 34 into'the tank 8. Furthermore, uid from the conduit 45 may escape through the conduitV kwhich pressure acting upon the piston 2|4 of the surge valve 9 moves the piston 2| downwardly and by means of the piston' rod 22, also depresses the plunger I2, thereby establishing communication between the upper portion of the cylinder I and the tank 8 through the openings I5 and I3.

The ram 3 now starts its retraction stroke. When the platen 4 approaches the end of its return stroke, the arm I 34 engages the collar |35 of the rod |35 and, while lifting therod |36, causes the cam |31 to engage the follower II9 which now slides along the cam surface thereby moving the valve member |.I6 toward the right. When the platen 4 has reachedv the vend of its return stroke, the valve member IIS has completed -its rightward movement against the thrust of the spring |22 so that the valve member I|5 again occupies the position shown in Figure 1. It will be noted that in this position the surge valve 9 is still held open due to the pressure in the conduit' |29 acting upon the piston 2| of the 4 surge valve 9.

As soon as the valve member I|4 is moved by the engagement of the follower |I8 with the cam |31 into its right-hand position as shown in Figure 1, the pressure iluid of the pilot pump 19 is by-passed through the conduit'l26, the bore |05, and the conduits 04 and |03, the bore 95 and the'conduits 99, |00 and I0| back'to the suction side of the pilot pump. At the same time, both the conduits 64 and 5I communicate, as will be explained` below, with thetank 8 so It will be noted that, although the pump 43 ls now in neutral or no-delivery position. the valve member 55 still occupies the position it had during the return stroke. 'This is of particular `importance since the control means is thereby enabled immediately to make up any leakage in the cylinder I which may cause a drifting of the piston 2. For instance, if some downward movement oi' the piston 2, and thereby platen 4, occurs due to leakage from the lower part of the cylinder I, the .follower IIS will be moved `by the spring |22 somewhat toward the left, which movement due to the conilguration of the cam |31 engaged by the follower IIB is suihcient to have the piston I|4 close oiT the conduit |04. Fluid pressure from the -pump 19 will then pass through the conduits 80 and 80a, the bore 62. and the conduit 6|, into the righthand pu'mp arm 5| where it acts upon the plston 54 which, as previously explained, moves theiow-control member 50 toward the left so that fluid pressure is supplied to the lower pornon of the cylinder i and 1ifts the. piston 2 to its previous position.`

1f the control rod |09 when starting the operl ation of the press was left inthe position shown in Figure 2. for instance, by actuating the shift rod |69 so that its pin III is locked in the bayonet slot II2, fluid pressure from the pilot pump 19 will again movei the valve member B5 toward the left as previously described with the result that the delivery direction lof the pump 48 is reversed and the ram 3 starts a new downward stroke,l thereby establishing ffull automatic operation of the press.' However, if semi-automatic operation of the pressis desired, in other words, if, after completion of a press operation, it is desired that the ram 3 halts after completion ofits return stroke, it is merely necessary at the starting operationof the press to release the control rod |09 when the piston H5 of the i trol' rod |09 to its initial position shown in Figure 1.

- I'he operation of the device with the modification illustrated in Figure 4 is the same as described in connection with the construction of Figures 1, 2 and 3. The only exception is that instead of operating the valve member 84 of the valve'18 by iluid pressure from the variable delivery pump throughthe line 93 (which is now omitted), in the modification of Figure 4, the fvalve member |41 corresponding to the valve member 84 of the valve 18 is operated'by the lever III. -This is accomplished when the arm |34- oi the platen 4 approaches the end of its that the pressure upon the piston 51 in the lefthand pump arm 52 equals the pressure on the piston54 on the right-hand arm 5| of-the pump. Consequently, the springs 53 and 55 move the flow-control member 50 to neutral position Vso that the variable delivery pump does not deliver uid pressure.V As will be seen from Figure 1 in thisposition, the conduit 6| communicates with the.tank 3 through the bore 52 of the valve 53, .the conduits 30a. 80, |25, the bore |05, and the conduits |04,4 |03,valve 94 and conduits 99 and ||||I.4 ffrSimilarly, the conduit 64 communicates with working stroke and thereby engages the collar |33 and moves the" rod |35 against the thrust of the spring |55 downwardly so as to cause arm |43 of the'lever |4I to'shift in anti-clockwise direction. When the platen 4 moves again upwardly.

by engagement of the abutment I 53 shifts the valve member |41 toward-the right into its previous position.

Summary of operation operates the surge valve 9 to open it on the return stroke of the ram whereas the surge valve will deliver pressure fluid -into line. or |29 respectively. "The rightward movement of the consaid controlling means, a manually operable starter valve operable 4to initiate movement of .said pilot valve in one diction, and valve means trol valve member 65 in turn is controlled bythe I pilot valve 18, whilethe shifter valve member 96 controls the leftward movement of the valve mem-ber 65. 'I'he shifter valve 94 is selectively operated so` as to cause either full automatic operation, i. e. a plurality of continuously following' cycles without stopping, or to cause 'semis-automatic operation, i. e.'thepress will go through one single cycle andthen come to rest. It will also be noted that the pilot pump 19 constitutes a separate source of operative iiuid to operate the con- Ltrol valve 63. In this manner the control valve y which controls the system hydraulically has-a separate source of constant pressure entirely separate from the main iiuid circuit for operating the press as supplied 'by the main pump 48 so that the hydraulic circuit controlled 'by the pilot pump is not connected with the main uid circuit. The valve system 28 serves as a relief and cushioning -valve mechanism upon the 'return stroke -in order to enable the surge valve to be opened by the valve means operable by said plunger independpush back pressure. 'It also serves to by-pas'sf 30 the delivery of the pump 48 during that period.

It will be understood that I desire to comprehend within my invention such modifications as come within the scope of the claims.

Having thus fully described my inventionwhat I claim as new and desire toY secure by Letters Patent, is: i

l. In combination, a main cylinder, a main plunger reciprocable in said main cylinder and supporting a'n actuating arm, a iirst pump for delivering fluidinto said main cylinder to actuate independent of said starter valveand operable byY said platen to initiate movement of said pilot valve in the other direction.' y

3. A hydraulic system comprising in combination, a main cylinder, a main plungerrecip'rocable in said main cylinder and adapted to perform a working stroke and a retractioin stroke,- a variable delivery pump `for delivering uid into said main cylinder to actuate' said main plunger, a y pilot pump, hydraulically operable control means adapted to `be supplied with iiuid from said pilot pump for controlling the now of uid and the direction of deliveryof said variable delivery pump, a starter valve hydraulically connected with said pilot pump for initiating operation of said -hydraulically operable control means in one direc-I tionand being operable so as selectivelyv to cause said main plunger to eiect one working and re- 'o traction stroke and thereafter'to stop .orto efiect a plurality of working and retraction strokes,

ently of said starter valve for initiating operation of said hydraulically operable control means inf the other direction, and anadditional valve operable by said plunger and'adapted in cooperation with said startervvalve to effect both the move` ment of said variable deliveryiump to substantially no-delivery position and the lay-.passing of said -pilot pump. I 4. In combination, a.l plunger, fluid operable advancing and retracting means for'reciprocating said plunger, a rst pump for delivering uld .selectivelyrto said advancing or retracting means,

fluid operable controlling means associated with said pump for controlling the ow of iiuid and said main plunger and comprising fluid operable controlling means adapted to control the now of uid and the direction of delivery of said first` pump, a pilot pump for supplying uid to said controlling means, valve'means operable by uid from said pilot pump to control the supply of iiuid from said pilot pumprto said controlling means, a by-pass valve, a starter valve movable selectively into one position for causing fluid from said pilot pump to actuate said valve means, or into another position to cooperate with said bythe direction of ,delivery of said first pump, a pilot pump for supplying fluid to said controlling. means, valve means operable by iiuid from said pilot pump to control the supply of fluid from said pilot pump to said controlling means, a, bypass valve, a startervalve movable selectively into one position for causing :duid from said pilot pump to actuate said valve means,or into another position" to cooperate with said by-pass valve for by-passing said pilot pump, means operable by said plunger for actuating said b'y-Pass` valve tocontrol the flow of fluid from said pilot pump to said controlling means, and further valve means operable independently of said by-pass pass valve for toy-passing said pilot pump, cam y means operable by said actuating arm ofsaid main plunger for actuating said by-fpass valve to control the new of duid from said pilot pump to said controlling means, and furtherv valve means operable independently of said lay-pass valve and adapted in response to a predetermined position of said plunger to vary the flow of uid from said nrst mentioned valve means tosald controlling means. r

2. In combination, -a niain lcylinder., a main plunger reciprocable in said 4main cylinder and comprisin'ga platen, a reversible variable delivery pump for delivering fluid into said main cylinder to actuate said main plunger, spring means tending to hold the variable delivery pump in no-delivery position, iiuid operable controlling means adapted to control the ilow of fluid and the direction of delivery of said variable delivery pump against the thrust of said springmeans, a pilot pump for supplying fluid to said controlling means, av pilot valve 'operable in two different directions for controlling the flow of fluid to vaive and adapted in response to a predetermined pressure on said plunger to vary the flow -of fluid from. saidV first mentioned valve means to said f controlling means.

Q 5. In combination,` a main cylinder, a main plunger reciprocable in said main cylinder, a rst pump for delivering fluid into said main cylinder to actuate said main plunger, a second pump, valve means adapted to be supplied by uid from said second pump to control the now ofl iiuid and the direction of deiivery of said rst pump, a twoway starter valve hydraulically connected with saidvalve means and said second pump forv controlling the movement of said'valve means intoa 1 nrst position by fluid from said second pump for y initiating a working cycle of said -r'nain plunger,

. yielding means associated 'with said starter valveV for returning said starter valve to initial position Y l during the rst portion of said working cycle, and

means controlling, the movement of said valve means into a second position by iiuid from said. second pump and adapted in response to a prede termined position of the main plunger to bring about said lastl mentioned movement, thereby causing a reversal of the deliveryv direction of said rst pump. K

6. A hydraulic press comprising in combination apress cylinder. a press plunger reciprocable in said cylinder and supporting a press platen. a variable delivery main pump for supplying uid to said cylinder for causing said platen to perform a working and a retraction stroke, a uid operable servomotor associated with said main pumpto control the now of fluid of said main:

' said valve means and also including starter means hydraulically connected with said valve vmeans and said control member, said starter means being movable selectively into a first position relative to a predetermined position of said control member to initiate a. working stroke of said press platen, orinto a second position relative to said predetermined position of said control member to cause movement of said main pump into no delivery position to halt the platen, and cam means operable in response to a predetermined,

point of travel of said platen, irrespective of the position of said valve means, for shifting said control member into said predetermined position.

7. A hydraulic press comprising in combination a press cylinder, a press plunger reciprocable in said press cylinder and supporting an actuating' arm, a variable delivery main pump vfor supplying uid to said press cylinder to actuate said press plunger, two uid operable plunger means associated with said main pump and adapted to be operated selectively so as to vary the iiow of iluid and the direction of delivery of said main pump, spring means actingy upon said plunger means for urging said main pump into no-delivery position, a nrst valve, a pilot pump, fluid operable means associated with said rst valve for selectively moving the same into -a rst or second position to control the passage of iluid from said pilot pump to one or the other of said plunger means, a second valve, a third valve controlling in cooperation with said second valve the supply of fluid from said pilot pump to said yiiuidoperable means and thereby the position of said rst valve, a control valve controlling in cooperation with said second valve the now 'of fluid from said pilot pump to said iiuid operable means, and reciprocable means adapted to be operated by 9. In combination, a reciprocable plunger, uid

operable advancing and retracting means associated with said plunger foi` reciprocating the same, a reversible variable delivery pump for desaid actuating arm in response to a predetermined position of said press plunger for varying the position of said control valve. v

8. A hydraulic press comprising in combination a press cylinder, a drawing plunger 'supporting anactuating arm, a rst pump adapted to supply duid to said press cylinder for actuating said drawing plunger, a' second pump, servomotor means adapted to be supplied by 4fluid from said second pump to vary the ilow oi nuid from said ilrst pump, valve means interposed betweensaidsecond pump and said servomotor means, said v valve 'means being associated with adjusting means operable by iluid from said second pump to vary the position of said valve means, controlling means adapted to control the supply oi fluid from said second pump to one side of said adiusting means, shiitable means operable by said actuating arm for operating said adjusting means at Y other direction,

livering uid selectively to said advancing or said retracting means, yielding means tending to hold said pump in substantially no delivery position, iluid operable controlling means adapted to control the ilow of fluid and the direction oi' delivery of said variable delivery pump against the Ithrust of said yielding means, a pilot pump for rection, and valve means independent o f said starter valve and operable in response to apredetermined pressure on said plunger to initiate movement oi said pilot valve in the other direcx tion.

10. In a hydraulic press, a fluid operable drawing plunger adapted to perform a drawing stroke and a retraction stroke, a. reversible variable delivery pump for supplying pressure iluid to said drawing plunger to actuate. the same, yielding means continuously urging said pump to substantially no-delivery position, iluid operable piston means with oppositely eiective piston areas for'selectively sluiting said pumpto forward or retraction stroke position, a pilot pump for supplying iluid to said piston means, valve means interposed between said pilot pump and said piston means for controlling the ow of uid from said pilot pump to said piston means, means assol 4elated with said valve means and operable by fluid from said piloty pump to shift said valve means, a reversing valve operable in response to a predetermined point of travel of said plunger for initiating a retraction stroke thereof, spring means operable during the ilrst portion ,of said retraction stroke for returning said reversing valve tor no-retraction position without aiecting said retraction stroke, and controlling means re- Ya pilot valve means for controlling the movement oi said control valve in one direction, a pilot pump adaptedto supply operating fluid tosaid control valve and pilot valve means, means to mechanically operate said pilot valve :means at a given point in the cycle of operations for reversing the direction of ilow of iluld from said uid source, and a shifter valve means adapted to control the movement of said control valve means in the 12. A hydraulic press comprisingfin combina` tion a ram, iiuld operable advancing and retracting means for reciprocating said ram, a main pump for delivering vpressure iluid selectively tov said advancing or retracting means, fluid operable control means associated with said pump and operable to cause said pump to deliver fluid selectively to said advancing or said retracting means. a'control valve for controlling the supply oi' actuating fluid to said control means a pilot valve,forv said control valve, a forward shifter valve, a stop-shifter` valve, said forward shifter ld cally interconnected andbeing operable to control the movement of said control valve in opposite directions, means connected with said advancing 4means for conveying pressure therefrom to said valve and said stop shifter valve beinghydrauii-

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