US2029708A - Hydraulic press - Google Patents

Description

1935- ,J. K. DOUGLAS ET AL 2,029,708

HYDRAULIC PRESS Filed March 14, 1930- 3 Sheets-Sheet 1 GEORGE L... HEIDEN. 4 JAMES K.DE]LJBLAS.

Feb- ,1936- J. K. DOUGLAS ET AL 4 2,029,708

HYDRAULIC PRESS 7 Filed March 14, 1930 3 Sheets-Sheet 2 gwwntou E EDRGE L. HElDEN. JAMES K. Duu GLAS.

Feb. 4, 1936. J. K. DOUGLAS ET AL HYDRAULI C PRES S Filed March 14, 1930 5 Sheets- Sheet 3 E 4% D E 3wtnnoz& GEORGE L..HE| DEN. JAM ES K-DDLIELAS.

Patented Feb. 4, i936 HYDRAULIC PRESS Jamcs'K Dougli ts and George L. 'Heiden, Mllwaukee, wis assignors to The Oilgear Company, Milwaukee, Wis., a corporation of Wisconsin.

Application March .14, 1930, Serial No. 435,750

18 Claims.

This invention relates to hydraulic presses. One object of the present invention is the provision of an improved hydraulic drive for presses capable of efiecting extremely rapid reciproca- 5 tion thereof through a short stroke. This we have accomplished by the use of a pump fed hydraulic circuit under the control of a reversing valve which responds to pressure at both ends of the stroke to automatically reverse the circuit.

Other more specific objects and advantages will appear from the following description of .an illustrative embodiment of the present invention.

In the accompanying drawings:-

Figure 1 is a front elevation of hydraulic press 1., embodying the present invention.

Fig. 2 is a side elevation thereof.

Fig. 3 is a diagrammatic illustration of the hydraulic system employed for driving the press.

Figs. 4, 5 and 6 are views partly in section and partly in elevation of certain of the valves shown in Fig. 3 together with their associated control mechanism, illustrating different characteristic positions thereof. Fig. 7 is a sectional view of the reversing valve shown in Fig. 3, illustrating a second position thereof.

Fig. 8 is a sectional view of the starting valve illustrating a second position thereof.

Fig. 9 is an elevational view of the control mechanism of Figs. 4, 'and 6 showing an adjusted condition thereof.

The press shown in Figs. 1 and 2 comprises an appropriate base Ill, standards H, and head l2, tied together by heavy tension rods l3 which also I. The platen I4 is supported and actuated by a piston l5 working in a cylinder l6 on the head I2. A collar |1 threaded on a boss l8 formed on the piston rod l9 coacts .with the face o'n thethead l2 to limit the upward or return stroke of the platen M. The piston I5 is actuatedby liquid supplied to the upper or lower ends of the 2|- and 22 under thecylinder 16 through pipes control of a reversing valve 23 of a typepreferably such as will now be described. 1

The valve 23 comprises a housing longitudinally bored to' receive a plungerhavingtwo heads 24 and .25 closely -fitted for lengthwisemovement therein. The opposiw ends of the bore communicommunicates space between the heads and-25. Head 24 controls. the pipe 2| and head 25.,controls the-pipe The: arrangementyis. such, that, when the serve as guides for a vertically reciprocable platen 1 haust. pipe 4 J cate with. each other through a pipe 26 whichconmeets with an exhaust: pipe 21." A supply;pi pe 28 at; all times 3 with; .theqannular,

plunger of valve 23 is in the lower position of Fig.

3 pipe 22 isconnected with the supply pipe 28, and pipe 2| is connected with the exhaust pipe 21 through pipe 26; and when the plunger of this valve assumes the upper position of Fig. 7 pipe 5 2| is connected with the supply pipe 28, and pipe 22 is connected with the exhaust pipe 21 through pipe 26.

A low pressure relief valve 29 interposed within' the pipe 22 offers some resistance to the flow of liquid through the pipe 22 from the lower end of the cylinder l6 and thus serves to support the piston when the press is at rest and the pipe 22 open to exhaust. A check valve 30 connected across the relief valve 29 permits a free flow of 15 liquid through the pipe 22 intd the base of the cylinder.

The plunger of valve 23 is hydraulically actuated by auxiliary plungers 3| and 32 formed at the opposite ends thereof and working in cylinders 33 and 34 respectively applied to the opposite ends of the valve housing. Pipes 35 and 36 connected with the cylinders 33 and 3|, respectively, are controlled by an appropriate pilot valve 31 of a type preferably such as will now be described. l

The pilot valve 31 shown in Figs. 3, 4, 5 and 6 comprises a block bored to receive a plunger having two heads 38 and 39 fitted for axial movement therein. The opposite ends of the bore communicate with each other through a passage 40 formed in the valve block, and an exhaust pipe 4| communicates with the passage Mlthrough one end of the bore. A pressure pipe 62 communicates at' all times with the annular space between the heads 38 and 39.. Head 38. controls the pipe 35, and head 39 controlsthe pipe 36, so

. that when theplunger of valve 31 is in the elevated position of Fig. 3 pipe 35 communicates with the pressure pipe 42, and pipe 36 communicates 4" with the exhaust pipe 4| through the passage 4|),

1 and when this plunger is in the lower position of Fig; 5 pipe 36 communicates with the pressure pipe-42, and pipe 35 communicates with the ex- It will thus be noted that when 31 is elevated, pressure is 42 through-pipe 35 to the. auxiliary plunger 3| to. lower the plunger. of H valve 23, and when the plunger, of valve 31 is loweredipressureis transmitted from pipe 42 through pipe 36th the auxiliary plunger 32 to elevate the plunger of .valve. 23. I y

A: chokecoil 43 in. the form of acoil of small diameter tubing .is preferably interposed within 1 the pipe 36 so as to "restrict the flow therethrough the plunger of valve transmitted from pipe from the cylinder 34 and thus retard the downward movement of the plunger of valve 23. A check valve 44 connected across the choke coil 43 permits a free flow of liquid through pipe 36 to the cylinder 34 to thereby permit a rapid upward movement of the valve plunger.

The pipe 28, is supplied with driving liquid; through a cut-off valve 45 from an appropriate pressure source, such as a variable displacement pump 46 of a well known type. The pump shown is fully described in the prior patent to Walter Ferris, No, 1,558,002, issued October 20, 1925.

It is driven at constant speed from an appropriate power source through a pulley 4'! and delivers.

ished by liquid returned thereto through a pipe 52'. A low pressure relief valve 53 connects the pipe 52 to a pipe 52 and maintains a low pressure therein. A gear pump 54 of a well known type, ordinarily contained in the pump housing, receives liquid from the sump 5| and discharges into a pipe 55 which connects with pipe 42. A low pressure relief valve 56 connected with pipe 55 determines the degree of pressure therein.

In the system shown the housing of valve 45 is formed integral with that of valve 31 and is longitudinally bored to receive a plunger having three heads 51, 58, and 59. The upper end of the bore is connected to a drain pipe 60 connected with pipe 52, and. the lower end of the bore communicates with the drain passage 40. Head 51 controls the exhaust pipe 21 from the valve 23; pipe 52 communicates with the annular chamber between the heads 51 and 58; pipe 28 communicates with the annular chamber between the heads 58 and 59; and the head 58 controls the pipe 48. The arrangement is such that when the plunger of valve 45 is in the lower position of Figs. 3 and 6 pipes 21 and 28 are blocked, and the supply pipe 48 from the pump is connected with the return pipe 52 leading to the sump through the relief valve 53 and pipe 52'; and when the plunger of valve 45 is in the elevated position of Figs. 4 and 5 the exhaust pipe 21 is connected with the return pipe 52, and the supply pipe 48 is connected with pipe 28 so that liquid delivered from the pump 46 is directed to the upper or lower end of cylinder l6 dependent upon whether the plunger 01' valve 23 is elevated or depressed,

The plunger of valve 45 is elevated by a stem 6| depending therefrom and carrying a head 62. A spring loaded detent 63 cooperates with notches 64 and 65 formed in the stem 6| to yieldably retain the same in elevated or depressed position. The plunger of valve 45 is lowered by a fluid actuated auxiliary plunger 66 projecting from the upper end thereof and working in a cylinder 81. A pressure pipe 68, connected intermediate the ends of cylinder 61 and controlled by the plunger .86, is'supplied with liquid under pressure from the gear4pump through pipe 55, the outer end of cylinder 61 being connected with a pipe 69 leading tothe drain pipe 52'. Pipe 69 contains a low pressure relief valve III which offers 'a definite resistance to the escape of'liquid therethrough from cylinder 61 to the drain pipe 52, and a check valve 'Il connected across the relief valve 10 permits free passage of liquid through pipe 69 to the cylinder 61. A small pressure accumulator 12 of a well known type is preferably connected with the pipe 88 for a purpose which will later appear.

The plunger of the pilot valve 31 is hydraulie c-ally operated in both directions by a. double acting piston 13 connected to the lower end thereof and working in a cylinder 14. A pipe I5, leading from the cylinder 14 intermediate. theends thereof and controlled by the piston? 13-1 ,QOm-

municates with the return pipe 52. A pipe I5 communicating with the lowerend ofcylinder 14 connects with pipe 2| through is, nigh pressure relief valve Tl which offers high resistance to the flow of liquidfrom pipe 2| to cylinder 14. A

check valve ltcon'nected across the valve ll permits a free flow of liquid through pipe 16 in the opposite direction. Similarly a pipe 19 communieating with the upper end of cylinder 14 connects with pipe 22 through a'high pressure relief valve which offers high resistance to the flow of liquid from pipe 22 to cylinder 74, and a check valve 8| connected across valve 80 permits" a' free now in the opposite direction. A with pipe 19 beyond the valve 88, communicates pipe 82, connected with the end of cylinder 5'! through pipe 68 and contains a relief valve 83 which offers consider able resistance to the flow of liquid from pipe 18 to the cylinder 61. Referring to Fig. 3 it will be noted that the main piston |5 of the press is elevated so that the stop collar |l abuts the lower face' of the iv l2; that the plunger of the reversing valve 23 i depressed so that'pipe 28 is connected'withthe lower end of cylinder l6, and pipe 21 is connected with the upper end of cylinder l6; that the plunger of the cut-off valve 45 is depressed so that both pipes 21 and 28 are blocked and the piston I5 is thus locked in elevated position, and so that pipe 48 is connected with pipe 52 andthe entire discharge from the pump escapes through the low pressure relief valve 53 to the sump in the pump casing; and that the plunger of the pilot valve 31 is elevated. I

To start the press the plunger of the cut-01f valve 45 is elevated into the position of Fig. 4 by forcing the stem 5| thereof upwardly to thereby connect pipe 21 with the return pipe 52 and pipe 28 with pipe 48. Pipe 48 fl'Oll: the pump is thus connected to the lower end of cylinder 6 through pipes 28 and 22, and since the piston |5 cannot move upwardly the pressure in the lower end of the cylinder l6 rises, the relief valve 8|! opens and pressure is transmitted through pipe 18 to the upper end of cylinder 14' to lower the plunger of pilot valve 3'! into the position of Fig. 5. Pressure from the gear pump 54 is then directed from pipe 55 through pipes 42 and 36 to the cylinder 34 to thereby elevate the plunger 01' the reversing valve 23 into the position of Fig. 7. The lower end of cylinder 6 is thus connected through pipes 22, 26, and 21 to the return pipe 52, and the pipe 48 from the pump is connected through pipes 28 and 2| to the cylinder I6 and the piston |5 starts down.

upper end 0t The piston |5 continues downwardly until the pressure in the upper end of cylinder I6 isin-' creased by the resistance of the work to sucha degree as to open the relief valve TL'whereupon so-that the lower end of the cylinder l6 receivesthe discharge fromthepump through pipes 48,

24, and 221and the piston lpstarts up. This upward movement continues until arrested by the engagement of stop collar I1 against the'face of the head 12, whereupon the pressure in the.

lower end or the cylinder I6 againrises causing I the relief valve to reopen and to again transmit pressure t upper end of cylinder 14 to again lower the plungerof the pilot valve 31 so as toagain elevate the plunger of the reversing valve 23 and thus cause the piston I5 to again move down. The piston I5 thus continues to reciprocate, automatically reversing at both ends of the stroke in response to arise in pressure in the system, as long as the plunger of the cut-ofi valve 45 remains in the elevated position of, Figs. 4

and 5. I

In the press shown provision is made forcom trolling both valves 45 and 3! so that the press may be made to operate continuously in the manner described or to come to rest after completion of a single cycle including a down strokeand return stroke ofthe piston. Mechanism for this purpose comprises a slide plate 84 guided for vertical reciprocation in a bracket 85 fixed to the side of the press below the valves 31 and 45. I The plate is connected to and actuated by a piston 86 working in a cylinder 81.

controlled by an appropriate valve 90 in the form of a housing longitudinally bored to receive a plunger having two heads 9| and 92. A pressure pipe 93, connected with the gear pump through pipe 55, communicates with the annular space I between the heads 9| and 92. Pipe 88 is controlled by the head 92, and pipe 89 is controlledby the head 9I. Both ends of the valve bore communicate through pipes 94 with the drain pipe I 60. A spring 95 hearing against the head, 96 of a stem 91 yieldably retains the plunger of valve 90 in the lower position of Fig. 3 in which position pipe I13v is connected with pipe '88 so that the piston 86 and plate '84 assume thelower position.

of Fig. 3. The plunger of valve'90 may be elevated into the position of Fig. 8 by de'pressionof pedal- 98 on one end [of a lever whose other end99 is engaged beneath the head 96. i 1 When elevated the,

valve 90 connects the I pressure pipe .93 'with the pipe as to thereby elevate the piston stan the plate 84 into the position shown inFig s; 4, 5-,;

and 6.

A rocker elernent I00; pivotally: mounted at, IIJII on the slide plate 84, carries "a finger I02 normally I j engaged beneath the head 62 onthestejm 6| of valve 45. Theelement Iflfl, also carriesa trip B16717 ment I03 .rockablysupported'at I04ther'eon. At

step screw I05, in thef tail of the trip f1I03coacts with a lug l06 pt the rockerelenien I00 to limit, the rocking action oi thetrip thereoni; A spring m oonneetingfthe tail of the'ti'i'p and ast q I08 on theslide platefjserves tofyieldablyretain the, trip androckerelementin the positionsfshowh in; Fig. 3 with thefing'er I02beneathj: the head" 62., The stud IOB,also limits the rocking action of g An SQIOS n, .q

ciprocationon the bracke 85.1Infthis instance the frame iis co necte withfa bar IIZ' uided in} brackets H3 and -II4}fon the brackeflaiand is lunger oi valve 31 ted b1 a d with t e; througha tail rod II5.

The frame III alsoIcarr eslja camj I ltior'co V;

I I I-9 M 9P I eeka r I ment Pipes 88 and 89 connected to the opposite ends of the cylinder 81 are stud I I9 projecting from the supported upon a slide plate 84. A trip lever I20 also mounted on the stud I I 9 is connected to the lever I I8 through a bolt I so as to move therewith, a second perforation I22 being provldedin the lever I20 to receive the bolt I2I and to thereby permit adjustment of lever I20 relativeto lever H8. Ajspring I23 connected to-the lever I20 and to the stud I00 urges both levers toward the-rright. A stop pin I24 projecting fromtheplate 84 coacts with lever II8 to limit the movement thereof toward the right. Thelever I20 is provided with a nose I25 for cooperation with the tail I26 of a pawl I21 supported as at I28onthe bracket 85. The pawl is provided with a nose I29 for engagement be-I to retain the plunger of the pilot valve 31 ele-I vated, and with the finger I02 of the rocker element I00 beneath the head 62. Then to start the press the operator depresses the pedal98 to thereby elevate the plunger of valve 90 and cause the piston 86 and slide plate to rise into the positionof Fig. 4. I As the plate moves up the finger I02 forcesthe plunger of valve 45 into the elevated position of Fig.4, and the nose I25 of lever I20;strikes the tail I26 of the pawl I21 to effect withdrawal of the nose I29 thereof from the shoulder I30, so that the plunger of valve 31 is them free to lower as soon as pressure is transmitted to-the upper end of cylinder 14 through pipe 19 from the lower end of cylinder I6. When this occurs the plunger of valve 23 .is elevated in the manner previously describedand the piston I5 moves down. As the plunger of valve 31 and theirame III move down the oam IIIi on the i frameacts upon the head II1 of lever I I8 so as to force both levers I I8and I20 toward the left so that the nose I25 is withdrawn from the tail I26 of pawl- -I21 permittingthe same to assume the positicn shown in Fig. 5. I I

I Then when the pistonl5 reaches-theend of its down stroke and the plunger otvalve 31 isagain elevated, by; pressure transmitted through pipe 16 fromthe upperend of cylinder IS the frame I I I Ialsomoves upwardly andthe lug, I I0 thereon strikes the nose l0 9o f the trip d mentia; and

tilts the rocker element I00;toward then/left, to

thereby withdraw the ,Ifinger I 02 from beneath the head 62,- as indicated in 6., And when I the plunger of valve 31 and the frame; I I I reach :their; elevated positions the nose I29 of the pawl I21 a a m ll en a s, Ib e ihj th hem e {I30 on the frame I I I'to therebyI lock the valve' tand' framein elevated position. I This elevation I of; valve-1 31 eflects depression. e5 I the valve 23 in the manner previously described and the piston fi st ts uni; I T e wh e t e Pis n I ir ae s theIendof itsup stroke the pressure inthe lower end ofcylinder e r igr ases an br ax ji fiueh .I ie l s it we s g i i r ii d r e1, and-acting on the auxiliary plunger 33 forces the Ilplungerlof v ve downwardly into the 'pgsition of Fig; 6; Pipe' 48 is thus connected it the re i turn pipe 52andithe piston I5. cornesto rest. It

will be .noted that; the 1 pressure transmitted tnrtugnvaive 80 and pipe 19 to the upper end of when we T etai Waite Pierr I valve :1 because of the detent m. The pedal 98 is then released permitting the plunger of valve 80 to r'eassume the depressed position of Fig. 3-,

whereupon the piston 86 and slide plate 84 lower adjusted, by manipulation of the screw I05, that the nose I08 thereon is retracted from the path of travel of the lug IIO, (see Fig. 9); and the lever I20 is advanced with respect to lever H8 by transferring the bolt I2I into the second perforation B2, so that the nose I25 is never withdrawn from beneath the tail I26 of the pawl I21. With the parts so adjusted the pawl I21 is held in inactive position, so as not to interfere with the lowering of the valve 31, so long as the slide plate 84 is elevated; and also the rocker element I00 remains unaffected by the lug I I 0, so that the finger I02 remains beneath the head 62 and thus retains the valve in elevated position so longas the slide plate 84 is elevated. With the parts thus arranged the press is ,started by depressing the pedal 98 to thereby elevate the plate 84 and the plunger of valve 45 in the manner previously described. With the plunger of valve 45 retained in elevated position by the engagement of the finger I02 beneath the head 62, and with the plunger of the pilot valve 31 free to reciprocate in response to pressures transmitted through the valves 11 and 80, the piston I5 will continue to reciprocate until the pedal 88 is released to thereby lower the plate 84 into the position of Fig. 3. Thereafter, as the piston I5 reaches the upper end of its return stroke, the pressure in the lower end of the cylinder I6 is transmitted through valves 80 and 83 to the cylinder 61 to return the plunger-of valve 45 into the lower position of Fig. 3 to thereby stop the press.

Provision is also made for stopping the press at any point in the cycle; Mechanism for this purpose comprises a lever I35 rockably supported as at I36 on the side of the press. One arm I31 01' this lever is connected through appropriate linkage I38 with a hand lever I39 rockably supported within convenient reach of the operator. A spring I40 connected with the link I38 and the frame of the press yieldably retains both levers in the positions shown in Fig. 2, with the arm I31 resting upon a stop pin I4I projecting from the side of this press. Another arm I42 of lever I35 carries a roller I43 normally disposed above the head 62 and operable thereon to depress the plunger of valve 45. A third arm I44, depending from the lever I35, carries a roller I45 for coaction with the tail I46 of the rocker element I00 to swing the same and the finger I02 from beneath the head 62. The arrangement is such that when the hand lever I39 is raised lever I35 is rocked clockwise'so that the roller I45 strikes the tail I46 of the rocker element I00 to displace the finger I02 from beneath the head 62, and the roller I43 strikes the head 62 to thereby lower the plunger of valve 45 into the position of Fig. 3. When, this occurs the pipe 48 from the pump is connected to the return pipe 52, so that the pressure flow in pipe 28 is destroyed and the press tone.

It 11 be noted that the piston 86 is actuated by liquid supplied from the gear pump 54 through the valve 90, and that the auxiliary plungers 3| and 32 are also actuated by liquid supplied from the same pump through the valve 31. 'The accumulator 12 functions as an auxiliary pressure source to insure prompt and complete actuation of the valve 23, regardless of the demands made upon the gear pump 54 by the cylinder 81. The accumulator 12 is normally maintained in a charged condition by liquid supplied from-the gear pump through pipes-55 and 68, and whenever the plunger of valve 31 is shifted into a new position, liquid discharged from the accumulator may pass through pipe 68 to pipe 42 to thus augment the flow from the gear pump and thus insure a prompt flow of liquid to one of the actuating cylinders 33 or 34 -of the valve 23. A check valve I is preferably provided in the pipe to prevent escape of liquid from the accumulator to the valve 90 and cylinder 81 so that the accumulator may be reserved as a source of supply for the valve 31 and the auxiliary cylinders 33 and 34 of the valve 23.

From the foregoing it will be noted that a hydraulic drive has been provided which responds automatically to stalling pressures in the press cylinder to efiect prompt reversal of movement at both ends of the stroke. In the press shown reversal at the end of the working or down stroke occurs as the result of the increased pressure produced in the upper end of the cylinder I6 by the reaction between the dies, and reversal at the end of the return or upward stroke occurs as a result of the increased pressure produced in the lower end of the cylinder by the reaction between the stop collar I1 and the face 20 of head I2. Since reversal thus occurs as the result of pressure rather than piston movement, an extremely short stroke is possible with a consequent increase in number of strokes per minute. In fact, a blanking press of one hundred and twenty tons capacity, equipped with a hydraulic drive embodying the present invention, has operated successfully at spwds as high as one hundred and twenty cycles per minute, executing a one-eighth inch stroke, and providing sufilcient clearance between the dies for feeding purposes.

Various changes may be made in the embodiment of the invention hereinabove described without departing from or sacrificing the advantages of the invention as defined in the appended claims.

We claim:-

-1. In a press the combination of a reciprocable member, means including a pump fed hydraulic circuit for operating said member, valve mechanism in said circuit for reversing the flow therein to thereby reverse the movement of said member, fluid actuated means for operating said valve mechanism, a hydraulically operated pilot valve for controlling said fluid actuated means, and a pressure relief valve connected with each side of said circuit and responsive to a predetermined pressure therein for directing liquid from either side of said circuit to said pilot valve for operating the same.

2. In a press the combination of a reciprocable member, means includinga hydraulic circuit for operating said member, valve mechanism in said circuit for reversing the flow therein to thereby reverse the movement of said member, fluid actuated means for operating said valve mechanism, a pressure relief valve connected with said circuit, a pilot valve actuated by liquid discharged through said relief valve for controlling said fluid actuated means, and means responsive to the pressure in said circuit exceeding a predetermined value for terminating the flow and rerender saidmemb'er inactive.

3,029,708 ducing the pressure in ,said circuit to thereby f draulic motor connected therein operating said member, a valvejmechanism operable to re-' verse the flow in said circuit to thereby reverse the movement of said. member, means responsive tothe pressure ingsaid' circuitfexceeding a pre- I determined value for operating saidvalve mech- Y anism, and a valve mechanism, operable in re sponse to the pressure in said'circuitexceeding a predetermined valueand operable independently of said pressure responsive'means for-disconnect ing said motor from said sourcetof thereby render said member inactive.

4. The combination o'fa reciprocablemember means including a hydraulic circuit for reciprocating the same,a valvemechanismautomatically"operable in responseto the pressure in said circuit exceeding a predetermined value to reverse the flow in saidcircuit to thereby reverse the movement or said member, a second valve mechanism operable to start and stop thelfiow in said circuitto therebystart a'ndstop said 3 member, means under the controloi the operator for shifting said seconjd named valve mechanism into starting position, means responsive to the pressure in said circuit exceeding a predetermined 1 value at the end of a stroke of said member for automatically returning said second named valve mechanism into stop positionjtdthereby cause said member to stop at the end of a reciprocation, and means adjustable tor'ender said pres sure responsive means inefiective to thereby cause "saidfmember to 1 continue to reciprocate until stopped manually, f r

5. The combination of reciprocable member,

means including a hydraulic circuit for recipro I eating -pne same, a valveiautomatically operable in response to the pressure in said circuit ex-j r V pressure 'insaid connections foreffectingautoceedingaj predetermined value I to reverse the va ve in o shiftingsaid dete second valve mechanism topermit "return"there-' not into stop; position, and means automatically,

said second valve into stop;

pos

flow in saidfcircuitto thereby reverse thefmovementjof, said mernberjasecond valvejoperable to start and stop the fiowjn'saidcircuit to thereby t an to s i mem er a der e control of p the operator "ior? shitting} said second starting positionfjsaid "mearis "includ ,ing a detentadjustablelto. either holdsaid second "valve in startingQp'ositio or oj'beautomaticalim m tibj i i r into sto posit o and m s pressure in said eciprocable ab e $92 itic'n at the end of a stroke of said member.

said f rst named valve mechanism.

' said auxiliary pump, fandj' af' pilot valvefautomaticallypperable in response H to predetermined f'pressures in, said circuit tor controlling said recircuit exceeding a Ipredetermined valueat; the end or, a stroke or said" mint; "Yber for' autoinaticallyr urnin i x idsecondyalve,

into ,si'liop position,

same, a rever jto 'eversethe 0 means including ,ahydraul ic circuitfor operat- 1 p,

1-1, 1 ingthe jsame;=;,valve :mechanism: automatically operable to. reverse thew flow '3 in? said; circuit to I 1 thereby: reverse vthe movement of: said member at theiend 0t each stroke, a second valve 1 m z nism o er'able to ren er said circuit active or 1 member,

.versing valve ,socia '7. The combination of a reciprocable member,

r l means including a hydraulic circuitforfoperat- 'ai e inflamm on otji ir c p q e membenahydraulic circuit'supplied' withinotive liquid fromfasuitable fsourceand havinjg"ahying the same; valve" mechanism automatically operable gto reverse the flow" in'saidbircuit to thereby reverse the movement of *said member 5 at the end of each stroke, asecond v'alve'mechfond valve mechanism to permit return thereof into stop position, said 'detent shiftingmeans being adjustable to render the same unaflected by 8. The combination of a reciprocabiemember,

hydraulically actuated "means for operatingthe same, a pressure responsive valve for reversing the movement of said member at the end of each stroke, means ior releasably retaining said valve in one position, a second valvefor starting and stopping said member, means operable to shift said secondjvalve into starting position, said last 25 named means being operable to release said retaining means to permit said-second valve to assume a secondposition, means normally operable to releasably retain said second valve in starting position,means responsive tomovement of said first named valve into said first mentioned position for releasing said last named retaining means, and pressure responsive means for returning said second valve into stcp position.

'9. The combinationof a reciprocable member, 35

hydraulically actuated means for operating said member, a pump, hydraulic drivingconnections between said pump and saidjoperating means,

' an auxiliary pump, a reversing valve in said connections actuated by pressuregeneratedby said auxiliary pump for rversingithe movement of said member; and a pilot valve respo'nsive to the 'maticjoperationbf said reversing valve to cause reciprocationofsaid member. j

lb. The combination [of a reciprocable member, a puinp fed hydraulic circuit for operating the same, an auxiliary pump, a, reversing valve in said circuit actuated by pressure generated by o auo for am m b :;1. v 1

'11". ecombination of a reciprocablelmember, a pump ied jiiydraui e circuit for, operating the 'g" valve ,in said circuit operable vement or said} member, an auxa t pressurel accuinulator. energized 1 915 3 5 lipumn Iq 'j e 'atms r S i 11 versing valve,.fan'd a pilot valve [responsive to 1 pressure fin -ai rcuip r eg troilingisaid refluid from said low pressure circuit to said actuating means to shift the reversing valve when the pilot valve is shifted; means for shifting the pilot valve when the platen approaches the limit of one of its reciprocatory movements and means responsive to the pressure in said high pressure circuit for shifting said pilot valve upon said platen stalling at the other end of its reciprocat- .sureresponsive actuating means for admitting fluid from said low pressure circuit to said actuating means to shift the reversing valve when the pilot valve is shifted; and means responsive to the pressure in said press operating circuit ex- 066Q1Ilg a predetermined value for automatically shifting the pilot valve when the platen reaches the limit of one of its reciprocatory movements.

14. The. combination with a hydraulic press including a reciprocatory platen; of a pump dischargeable in one direction only; means forming with the press and with the pump a high pressure hydraulic press-operating circuit; a reversing valve operatively connected in said circuit; a low pressure hydraulic pilot circuit; a pilot valve operatively connected in said low pressure circuit; pressure responsive actuating means associated with said reversing valve; hydraulic connections between the pilot valve and said pressure responsive actuating means for admitting fluid from said low pressure circuit to said actuating means to shift the reversing valve when the pilot valve is shifted; means responsive to the pressure in said press operating circuit exceeding a predetermined value for automatically shifting the pilot valve when the platen reaches the limit of its pressing stroke; and other means for automatically shifting the pilot valve in the opposite direction when the platen approaches the end of its return stroke.

15. The combination with a hydraulic press including a reciprocatory platen; of a pump dischargeable in one direction only; means forming with the press and with the pump a high pressure hydraulic press-operating circuit; a reversing valve operatively connected in said circuit; a low pressure hydraulic pilot circuit; a pilot valve operatively connected in said low presure circuit; pressure responsive actuating means associated with said reversing valve; hydraulic connections between the pilot valve and said pressure responsive actuating means for admitting fluid from said low pressure circuit to said actuating means to shift the reversing valve when the pilot valve is shifted; and pressure responsive means associated with said pilot valve and having hydraulic communication with said high pressure circuit; said pressure responsive means being operable for shifting the pilot valve in one direction upon the attainment of a predetermined pressure in said circuit when the platen approaches the end of its pressing stroke.

j g 16. The combination with a hydraulic press including a reciprocatory platen, a main cylinder,

and a platen returning cylinder; of a pump dischargeable in one direction only; means forming with the pump and with said cylinders a high pressure hydraulic press-operating circuit; a reversing valve connected in said circuit for reversing the direction of fluid travel therein to reciprocate the platen, said valve including a valve casing formed with a valve chamber, a port communicating with said pump and with said valve chamber, a port communicating with said main cylinder and with said valve chamber, a port communicating with said platen returning cylinder and with said valve chamber, and means mounted for movement in said valve chamber for placing said pump in communication with said main cylinder when said means are moved in one direction, and for placing said pump in communication with said platen returning cylinder when said means are moved in the opposite direction; pressure responsive actuating means associated with said movable means for moving the latter in opposite directions; a low pressure pilot circuit; a pilot valve operatively connected in said circuit; hydraulic connections between the pilot valve and said pressure responsive actuating means for admitting fluid under pressure from said low pressure circuit to said actuating means to move said movable means when the pilot valve is shifted; means for shifting the pilot valve when the platen approaches the end of one of its reciprocatory movements and means responsive to the pressure in said high pressure circuit for shifting said pilot valve upon said platen stalling at the other end of its reciprocating movement.

17. The combination, with a reciprocable member, of a hydraulic circuit having a hydraulic motor connected therein for driving said memher, a power pump for supplying liquid to said circuit to operate said motor, a'hydraulically operated reversing valve connected into said circuit for reversing the flow therein to thereby effect reciprocation of said member, an auxiliary pump for supplying liquid to said reversing valve to operate the same, a resistance valve connected to each side of said circuit, and a pilot valve controlling the delivery of liquid from said auxiliary pump to said reversing valve and operated by liquid discharged through said resistance valves to thereby effect reversal of said reversing valve each time the pressure in either side of said circuit exceeds a predetermined value.

18. The combination, with a. reciprocable member, of a hydraulic circuit having a hydraulic motor connected therein for driving said member, a power pump for supplying liquid to said circuit to operate said motor, a hydraulically operated reversing valve connected into said circuit for reversing the flow therein to thereby eflect reciprocation of said member, an auxiliary pump for supplying liquid to said reversing valve to operate the same, a resistance valve connected to each side of said circuit, a pilot valve controlling the delivery of liquid from said auxiliary pump to said reversing valve and operated by liquid discharged through said resistance valves to thereby effect reversal of said reversing valve each time the pressure in either side of said circuit exceeds a predetermined value, and a start and stop valve connected between said power pump and said motor and operable to disconnect said motor from said power pump.

JAMES K. DOUGLAS. GEORGE L. HEIDEN.

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