US1899678A - Hydraulic press - Google Patents

Description

w. ERNST ET AL HYDRAULIC PRESS Filed April 11, 195o Feb.- 23,1933.

Patented Feb. 2s, 1933 UNITED STATES PATENT OFFICE WALTER naNsT, HOwAnn F. nAcmrLLrN, AND naman. THOnEsoN, OF MOUNT amm, omO,1Ass1eNons To THE HYDRAULIC PRESS MANUFACTURING COMPANY. or

MOUNT GILEAD, OHIO nYnnAULIo Pnl-:ss

Application led April 11, 1930. Serial No. 443,488.

Our invention relates to hydraulic presses and more particularly to hydraulic circuits and associated valve mechanism for operating such=presses.

5 It is desirable that the resses which are used for continuous operation for the pressing of a large number of pieces ofl work be operated rapidly. It is necessary that regardless of the speed of operation, certain l0 predetermined high pressures be employed during the final part of the pressing stroke of the platen or other tool. In order to obtain l high operatin speed without sacrificing the final high wor ing pressure various forms of l5 presses and press operating circuits have been provided which in eneral include a main pressing cylinder o relatively lar e diameter which is employed for effecting t e finall rt of each pressing stroke, a booster t0 cylindmr or cylindersl of relatively small diameter for driving the platen during the lirst part of the pressing stroke, and .a platen re-` turning cylinder or cylinders of small diameter for effecting rapid return ofi the l5 platen after a pressing stroke has been completed. Itisapparent that since the booster and platen returning cylinders are employed for only what may be termed light operation o the press, it is not necessary that the 0 Huid supplied to these cylinders be of as high pressure asA is usually required for the 4main pressing cylinder. v f

In accordance with our invention Vwe provide a press having a main cylinder, and

5 auxiliary cylinders servingfboth as booster cylinders and as platen returning or retractving cylinders. a source of low pressure iiuid pressure, hydraulic connections forming a [high pressure circuit with the main cylinder 0 and the high pressure source and also vforming a low pressure hydraulic circuit with the auxiliary cylinder and the low pressure source. We further provide valve means in said circuits 'for' controlling the application 5 ofhigh pressure fluid to'the main cylinder and the admission of low pressure fluid to the respective ends of the auxiliary cylinders.

The main` object of' our invention is to provide a hydraulic press and hydraulic means for the Operation thereof together embodying the principal features outlinedv above .and also further novel featuresjwhich will become apparent from a reading of the Afollowing detailedv description, the appended claims and the several views illustrated in the drawin in which: l

Figure 1 1s a vertical sectional view of certain parts of the press embodying our invention; and showing in diagrammatic form low and high pressure circuits for operating the press,certain valves being shown in secj tion and the several parts being shown in the positions they will occupy during the first part of a pressing stroke;

' Figure 2 is a sectional view of a surge shifting'valve showing its position during the final partofa pressing stroke;

. Figure -3 is a sectional view of a control valve showing the osition it will occupy during a return strole of the platen, and 70 FigureI 4 is a sectional view of a .modified form of surge shifting valve.

The illustrative embodiment of our inven tion shown in the drawin includes a press A, a` hi h pressure pum a low pressure 3pump' and a surge tan .D mounted at the to of the press. v

he press A includes a main cylinder 1, a reciprocatory ram 2 therein, aL platen 3 fastened to the lower end of the ram, two auxiliary cylinders 4 4 each having'a double act-v ingpiston 5 mounted for reciprocation therein and connected to the platen 3 by means ofva piston rod 6.

As stated above the working, or final part 86 of each ressing stroke is performed by the ram 2. he cylinders 4 are termed auxiliary cylinders for the reason that they serve to position the laten -in pressing relation` to the workbe ore`` final pressing and to re- 90 auxiliar cylinder and for. admitting such.

fluid be ow the pistons to the lower or r e tracting end 8of each cylinder. In the 1llustrative embodiment of our invention, the

means for admitting pressure fluid to therespective ends of the auxiliary cylinders include connections between the low pressure pump-C and both ends of the auxiliary cylinders, which connections form a low pressure hydraulic circuit with the surge tank, the

-auxiliary cylinders and the pump. These connections include a pump intake pipe 9 communicating a-t one of its ends with the surge tank and having a branch connection 10 at its other end which communicates with the pump, a low pressure delivery pipe 11 connected to the pump outlet and also to a control valve 12 which is adapted to direct low pressure 14 respectively. The particucylinders to which directed is deterpipes 13 and lar end of the auxiliary the low pressure fluid isv mined by the position of the control valve.

The control valve-is preferably of the balanced piston or spool type and in the form shown includes a valve casing 15 provided with a valve chamber 16 and a piston valve 17 mounted' for sliding movement in the chamber and .including spaced heads 18, 19-

and 20 and reduced connecting portions 21 and 22. The piston valve is provided with a longitudinally extending passage 23 which communicates directly with the valve chamber at the upper end thereofas viewed in the.

drawing and which also communicates with the chamber at the .lower end thereof by means of a diagonal passage-24 extending through the head 18, the passages 23 and 24 providing constant communication between the opposite ends of the valve chamber, and thus maintaining balanced pressures at the ends of the valve 17 facilitating the shifting of the latter. Lateral passages 25-25 provide communication between the longitudinal passage 23 and the chamber at a point between the heads 18 and 19 of the valve.

The llow pressure delivery pipe communi- Cates with the valve chamber 16 at a point intermediate the opposite ends thereof but somewhat closer to the upper end as viewed in the drawing, and the auxiliary pipes 13 and 14 communicate withV the chamber at i points respectively below and above the pipe It will be observed that when the piston valve 17 is in the Figure 1 position, low pressure'fluid delivered through the pipe 11 will pass into the valve chamber between the valve fluid from the pump to either the booster end 7 or the retractinflr end 8 of each auxiliary cylinder by means of auxiliary `iary pipe sages 25 and 23 in the piston valve, and the above the valve head 2O and an exhaust pipe 26, one end of which communicates with the chamber at itsextreme upper end and the other end of which/communicates with-the surge tank. Low pressure fluid being directed to thev booster ends of the auxiliary cylinders will move the pistons 5, 5 and consequently the ram 2 downwardly to initiate va pressing stroke. Fluid containedin the retracting ends of return to the surge tank through the pipe 14, that portion of the valve chamber whlch is above the valve head 20, and the exhaust pipe 26. When thel piston valve 17 is moved to its Fi ure 3 position .the low pressure Huid will be irected to the retracting ends of the auxiliary cylinders by way of the low pressure delivery pipe 11, the valve chamber 16 and the pipe 14. At this time the pistons 5 and the ram will be moved upwardly and the fluid contained in the booster ends of the auxiliary cylinders will be returned to the surge tank through the medium of the auxil- 13, the valve chamber 16, the pasexhaust pipe 26.

In order that the low pressure pump may be run continuously during intervals between operatino' strokes of the platen we have provided a ow pressure by-pass pipe 27 communicating at one of its ends with the low pressure delivery pipe` 11 and at its other end with the exhaust pipe 26, and a pressure operated by-pass valve 28 interposed in the bypass. pipe. This valve may be of any suitable and well-known form of pressure operated by-pass or relief valve.

For operating the piston valve 17 to control the movements of the ram and associated parts, we provide the valve with a stem 29 extendingthrough the bottom of the valve casing and pivotally connected as at 30 to a treadle 31 fulcrumed as at 32 on a fixed bracket 33. A spring 34 interposed between the treadle and thevalve casing serves to noru mally maintain the valve in its Figure 3 position. v

Hydraulic connections provided between themain cylinder, the surge tank and the high pressure pump form a high pressure hydraulic circuit with the afore-named elements. This high pressure circuit includes the pump intake pipe 9 which it will be seen supplies fluid to both pumps, a branch pipe 35 connecting the pump intake pipe to the pump. and a high pressure delivery pipe 36 which is connected at one of its ends to ,the discharge side of thepump and at its other end is conthe auxiliary cylinders will y with the cavit therein. A surge shifting valve37, to be ater described, normally provides communication between the main cylinder and the surge tank and is adapted to 5 cut off communication therebetween to -thus confine the discharge from the high pressure pump to the main cylinder. The high ressure circuit also preferably includes a igh pressure branch plpe 38 which communicates 510 at one of its ends with the pipe 36 and at its other end communicates with the valve chamber of the control valve 12 at a point below the pi 13. The exhaust pipe 26 hereinbefore dieescribed as forming part 'of the low 15' pressure circuit also forms a part of the high pressure circuit. When the piston valve 17 of the control valve is in the Figure 1 position, the valvehead 19 covers the end of the pipe 38 so that high pressure fluid is prevented 20 from flowing through the high, pressure branch pipe 3 8 and the entiredischarge of' the high pressure pump is directed -to .the surge shifting valve. When thepiston valve is in the Figure v3 position, fluid will flow from the high pressure pump through the pipes'36 and 38, the valve chamber 16 between l the heads 18 and 19 of the piston valve, the passages 25 and 23 in the valve and the exhaust pipe 26, being thereby returned to the surge tank.

It is desirable lthat when the platen encounters resistance to its downward travel resulting in a building up of pressure in the. auxiliary cylinder and the low pressure circuit, the

'35 main cylinder be shut off from communication with the surge tank so that the discharge of the high pressure pump will be confined to the main cylinder for completing the pressing stroke. This function is accomplished 40 by the surge shifting valve which includes a valve casing 41 and valve chamber 42 therein, a port 43 affording constant communication between the valve chamber and the main cylinder anda port 44 adapted to afford communicatiop between the surge tank and the valve chamber. A piston valve 45, having spaced heads 46 and 47 and 'a ,connecting stem 48 is mounted for sliding movements in the valve chamber. Means are provided for urging the valve to the right,\said means preferably comprising a spring 49 interposed between the v alve head 46 undone end of the valve casing and tending to hold the valve in its Figure 1 or open position.- When the valve has been moved to its Figure 2 position, the spring serves to move the valve from the Figure 2 position lto the Figure `lposition, thus constituting valve o ening means. A vent opening'50 in the val) the valve head 46 and the adjacent end of the casing provides for free shifting of the valve.

It willbe observedthat when the valve 45V is in its Figure 1 position the main cylinder, the high pressure pump andthe surge tank G5 are all in communication each with theothers,

ve casing between and that when the valve is moved to the left to its Figure 2 position the head 47 will cut ofi' communication ,between thevsurge tank and the cylinder so that the discharge side of the high pressure pump will communicate with the main cylinder only.

For automatically moving the piston valve 45 from its Figure 1 position to its Figure 2 position when' the pressure builds up in the low pressure circuit, we have provided the valve with a stem 51\which extends into a pressure chamber 52 formed in the valve casrlng, and a branch pipe connection 53 affording constant communication between the pressure chamber and the pipe 13. When the platen encounters resistance to its pressingstrokeand the pressure builds up in the low pressure circuit to a predetermined extent dependent upon the constant of the spring 49, the pressure acting upon the stem 51 will move the piston valve Vto its Figure 2 position whereupon the pressing stroke will be completed in the manner described above.

In some cases, particularly in large presses l of heavy constructlon, it may be desirable tov use pressure actuated means for moving the v p iston valve 45 t0 its Figure 1 or open position. The modified form of surge shifting valve shown in Figure 4 is provided wit-h such means which comprises a plunger 51a extendingfrom the valve head 46 into a pressure chamber 52 in the left hand end of the valve casing, the chamber 52l1 being in con- Y stant communication with the i'etracting ends of the auxiliary cylinders through the medium of a pipe 53".V Preferably the plunger 5la is of somewhat larger diameter than the plunger 51 so that when the platen and ram are performing the first part of a pressing stroke, the back pressure in the retracting ends of the auxiliary cylinders, which pres sure is due to the somewhat restricted exhaust opening, will 'be sufiicient to maintain the piston valve 45 in its Figure 1 position.l When auxiliaryv III pressing stroke, we provide the high pressure delivery pipe with anormally c osed pressure-operated valve 53 having an exhaust plpe 53b connecting the valve'to the surge tank and adapted to open when a4 predeteri mined pressure has been reachedA in the main cylinder 1 to thus place the delivery pipe in a communication with the surge tank. This valve serves as a safety valve as well as a pres- 4lowed to overtravel there might result the breaking of the piston rods 6, since if the work being pressed does not sufliciently resist the pressure exerted by the ram, the pistons 5 will contact with the bottoms of the auxiliary cylinders so that the piston rods will have to bear the strain of the full working pressure of the ram minus the slight resistance offered 'by the work. To prevent such injury to the press we provide branch pipes 54 which respectively communicate at one end with the lower ends of the .auxiliary cylinders between the-pipes 14 and thebooster ends of the cylinders at their other ends communicate with the pipe 14, and check valves 55-55, one in v each of said branches. The cheek valves are arranged to permit flow'of fluid from the booster ends of the cylinders to the pipe 14 when the upper edges of the pistons 5 have passed below the branches '54, but tov prevent fiow of fluid in the opposite direction. If the resistance offered by the work is insufficient to arrest the movement of the platen and the ram, the latter and the pistons 5-5 will descend until the upper edges of the pistons have passed below the branches 54 after which fluid will pass from4 the booster ends of the auxiliary cylinder through the pipe 14, the valve chamber 16, and the exhaust pipe 26, thereby returning to the surge tank. This will relieve the pressure in the low pressure circuit and also in the chamber 52 of the surge shifting valve, so that the spring 49 will return the piston valve to its Figure l position and further downward movement of the ram will be prevented. i,

The operation of the press 1s as follows.

` It will be assumed that the parts are in the A' will be in its Figure 3 position when the relative positions shown in Figure 1,' with the exception of the piston*y valve 17 which platen isl at rest in its uppermost position.

To cause a pressing stroke to be performed, -the tread'e 31 is depressed, thus moving the piston valve to its Figure 1 position. The

' low pressure pump will then deliver low presfas sure fluid to the booster ends of theauxiliary cylinders by way of the pipe 11, the valve chamber 16,. and the pipe 13, and the low pressure fluid acting upon the upper edges of the pistons 5 willi then initiate a pressing stroke of the platen. At this time the high pressure branch pipe 38 is cut olf from communication with the exhaust pipe 26 bymeans ofthe valve head 19 in the control valve, and the high pressure pump discharge will flow into the main cylinder to prefill the latter in conjunction `with fluid entering the cylinder directly from the surge tank by way of port platen encounters resistance to its downward travel pressure will build upon in the low pressure circuit and in the pressure cham- ,ber 52, thereby shifting the piston valve 45 of the surge shifting valve to its Figure 3 position so that the main cylinder will communicate with the high pressure pump only, and the pressing stroke will be completed. After the comp;.etion of the pressing stroke the treadle 31 is' released and the spring 34wi1l return the piston valve 17to its Flgure 3 position. This will relieve the pressure in the booster ends `of the auxiliary cylinder and also the pressure in the chamber 52 so that the piston valve 45 of the surge shifting valve will be returned to the Figure 1 position, 1nl

between the main cylinder and `the surge '.tank. The retracting `ends of the auxiliary cylinders will simultaneously be placed in communication with the low pressure delivery pipe through the medium of the valve chamber 16 and the pipe 14 and the platen and ram will be returned to their upper positions'. When the pistons 5 have passed above the pipes 13 iiuid will be trapped in the booster ends of the auxiliary cylinders and the by-pass valve 28 will automatically open so that the `discharge of the low pressure pump will be returned to the surge tank by means of the by-pass pipe 27 and the exhaust pipe 26. The various parts will then remain in the last-named positionsuntil the treadle 31 is againv depressed at which time another cycle will be performed inthe same manner communicate with an exhaust; a source of low pressure fluid pressure; a low pressure delivery pipe in communication with said low pressuresource; separate 1o.v pressure auxiliary pipes respectively communicating with said auxiliary cylinder at the opposite ends thereof; and valve means in said high pressure branch pipe for controlling communication of said high pressure source with said exhaust, and interposed between said low pressure delivery pipe and said low pressure auxiliary pipes for controlling admission of the low pressure fluid separately to the respective ends of the auxiliary cylinder to effect reciprocations of said ram. i

2. The combination with a hydraulic press including a main cylinder, a reciprocatory lao ram therein, an auxiliary cylinder and a piston therein and having connection with said ram; of a surge tank; a high pressure ump;

means forming a high pressure hydrau ic circuit with said surge tank, said main cylinder vand said pump and affording constant communication of said `maincylinder with saidA pump; a low pressure pump; means forming a vlow pressure hydraulic circuit with both ends of said auxiliary cylinder and said low pressure pump; a surge shifting valve in said igh4 pressure c1rcu1t normally 1n an open position affording communication vbetween vsaid main cylinder and said surge tank, and

movable to cut ofi' communication therebetween; means operable during the pressing stroke of the ram to move said surge shifting valve to its closed position to complete the pressing stroke; and a control valve interposed in said high and low pressure circuits for first directing lowpressure fluid to one end of said auxiliary cylinder to initiate the pressing stroke of the ram, and for then directing low pressure fluid to the otherv end of said auxiliary cylinder for effecting a return stroke of the ram.

\ 3. The combination with a hydraulic press including a main cylinder, a reciprocatory ram therein,\ an auxiliary cylinder and a piston therein and having connection with said ram; of a surge tank; a high pressure pump; means forming a high pressure hydraulic circuit withl said surge tank, said main cylinder and saidpump and including means pro'- viding constant communication between said main cylinder and said pump; a low pressure pump; ,means forming a low pressure hydrauliccircuit with both ends of said auxiliary cylinder and said low pressure pump; a surge shifting valve in said high pressure circuit normally i an-open position affording communication between said main cylinder and said surge tank, and movable to cut 0E communication therebetween; pres-v sureresponsive -means having hydraulic con- A nection with said low pressure circuit and operable upon a building up of pressure therein during a pressing stroke of the ram to move said surge shifting valve to its closed position to complete the pressing stroke; and a cont-rol valve interposed in said high and low pressure circuits for first directing low pressure fluid to one end of said auxiliaryl cylinder to initiate the pressing stroke of the ram, and for then directing low pressure fluid to the other end of said auxiliary cylinder for effecting a return stroke of the ram. A

4. The combination with a hydraulic press including a main cylinder, a reciprocatory y ram therein, an auxiliary cylinderv having e booster and retractingends; and a piston therein and havingl. connection with `said 1 ram; of arsource of gh ressure fluid ressure; a high pressure de 1veryp1pe a ordling constant communication between said source andsaid mam cyhnder; a source of low pressure fluid pressure; 'a lowl ressure delivery pipe in communication with said low pressure source; a low pressure auxiliary pipe communicatin with the booster end of said auxiliary cylinder; a second low pressure auxiliary pi e communicating with said. auxiliary cylin er adj acentto the retracting end thereof; valve means interposed `between said low pressure delivery pipe and saidilowaressure aux1liary pipes or controlling a sion of the low pressure fluid separately to the respective ends of the auxiliary cylinder toeflectreciprocations of said ram; a relief mispipe communicating at one -of its ends with said auxiliary cylinder adjacent to said second low pressure auxiliary pipe but between the latter and the booster end of the cylinderA and adapted to communicate at its other end with'an exhaust; and a check valve in said relief pipe and arranged to permit fluid to flow from the booster end of said auxiliary cylinder to said 'exhaust `when said piston has travelled past the relief pressing stroke of the ram.

5L The combinationl with a hydraulic press including a main cylinder, a reciprocatory pipe during a ram therein, an auxiliary cylinder having booster and retracting ends, and a piston` therein and having connection with said ram; of a surge tank; ya high pressure pump;

means forming' a high 'pressure hydraulic circuit with said surge tank, said main cyllnder and sa1d pump and aflordmg constant commun1cat1on between sa1d mam cylinder and said pump; a low pressure pump; means forming a low pressure hydrauhc circuit with both ends of said auxiliary cylinder and said low pressure pump; valve means interposed in said high and low pressure circuits and normally affording communication between said surgetank and said main cylinder, and between the retracting end Nof said auxiliary cylinder and said low pressure pump, said means being movable to first direct low pressure pump fluid to the booster end of said 'auxiliary cylinder and to afford communication between the retracting end of* said auxiliary cylinder and said surge tank to thereby initiate ma pressing stroke of said ram, to then cut oil communication between said main cylinder and said surge tank. to complete the ressing stroke, and to then place said hig ,pressure cylinder'and the booster end of said auxiliary cylinder in 'means forming a high pressure hy ram; of a surge tank; a high pressure (pum rau ic circuit with said surge tank, said mam cylinderand said pump; a low pressure pump; means forming a low pressure hydraulic circuit with both ends of said auxiliary cylin- "der and said low pressure pump; a surge shifting valve in said high pressure circuit normally in an open position affording communication between said main cylinder and said surge ltank, and movable to cut oif communicatlon therebetween; valve opening means normally maintaining said surge shifting valve in its open position; pressure responsive means in said low pressure circuit and operable upon a building upl of pressure therein during a pressing stroke of the ram to move said surge shifting valve to its closed position to complete the pressing stroke; a

control valve interposed in .said high andlow,

for reversing the -ilow of fluid in saidlow pressure cncult, and means connected to said surge valve and'being responsive to .pressure l pressure circuits for rst directing low presl sure fluid to one end of said auxiliary cyhnder to initiate the pressing stroke of the ram, and for then directing low pressure iuid to the other end of said auxiliary cylinder or effecting a return stroke of the ram; and means for relieving the pressure in .said auxiliary cylinder when the piston therein has reached a predetermined point during the pressing stroke" to thereby permit said valve opening means to return the surge shifting valve to its open' position.

7 The c-ombinationvwith a hydraulic press including a main cylinder, a reciprocatory ram therein, and auxiliary hydraulically operated means for operating said ram in both directions; of -a-surge tank; a source of high pressure Huid pressure; means forming a high pressure hydraulic circuit with sald high pressure source, sald `surge tank and said maincylinder; a sourc'e of low pressure iiuid pressure; means forming a reversible flow low pressure hydraulic circuit with saidl low pressure source and said auxiliary means for operating the latter; and means in said low pressure clrcuit for relieving the v'pressure in both of said circuits when said.

ram has tr'avelled a predetermined distance while performing a pressing stroke.

8. The combination with a hydraulic press including a main cylinder, a reciprocatory ram therein, an auxiliary cylinder, and a pis'- ton therein and having connectionwith said ram; a high pressure/pump; a surge tank;

means forming a high pressure circuit with sald pump; sad mam cylmdcr, and sald ltank and including neans providing constant communication between the discharge side vof said pump and said main cylinder; a low pressure pump, means connecting said low pressure pump to both ends of said auxiliary cylinder to form a low pressure reversible How hydraulic circuit; a' normally open surge valve for controlling communication between said surge tank and said main cylinder means

Images