US2148543A - Hydraulic press - Google Patents

Description

Feb. 28, 1939. R. w. DINZL HYDRAULIC PRESS Fild Oct. 25, 1935 Patented Feb. 2'8, 1939 PATENT OFFICE mimmo rREss .Richard w. Dinzl, Ncrbcrth, Pa, assigncr tc Balawin- Southwark Corporation, a corporation of Delaware Application octcbcr 25,1935, serial No.4 46,732

Claims.

This invention relates generally to hydraulic presses and more particularly to an improved combination wherebyla press platen, or other corresponding movable press element, moves Without any substantial tilting or canting action.

AThe problem has long existed with hydraulic presses of the type having a large platen, knife or other corresponding movable press element of considerable length, to insure uniform movement of such element at all points thereof soas' to avoid `tilting and the difliculties incident thereto. This problem is usually avoided in mechanical presses due to the use of crankshafts and connecting rods, and lt has been heretofore avoided in hydraulic i presses by so propo'rtioning the press frame, guides and diameter of the operating ram so as to structurally resist any tendency of the platen to tilt. Tilting is caused bythe dies'having a higher portion at one end than atV thel other; whereby the sheetmetal or other work piece creates greater resistance at the highv end'lfollowed by greater resistance at the otherl end. ,Also non-uniform" forc'esresisting' movement ofthe element' maybe caused". by the` fact that `such c1cmcntisakmfe wherbr warming f ong the length ofthe knifegdueto the character of material being' cut o r duej to the knifebeingof the ldiagonal type wherebyfthe cutting commences atene end thereof and progresses across tothe other end.

It is an object of my invention to provide an improved hydraulic press, and operating means therefor whereby all points of the movable press element are inherentlyl moved substantially uniformly regardless of varying degrees ofl pressure that may be momentarily required at different points of the platen, as aresult, I am able to avoid the necessity for large orexcessively strong structural elements that would otherwise be required to obtain suchruniform movement. y

In one specio aspect of the linvention I accomplish this improved result by employing a. plurality of operating rams and cylinders and providing simultaneously driven positive displacement pumps, kone for each cylinder, whereby each-ram is moved atthe same uniform speed regardless of whether movement of one ram is resisted by a greater force than that of another ram. It will of course be appreciated that while the pumps are 'preferably commonly driven to insure absolute uniform Supply ofliquid simultaneously to each cylindenyet under certain circumstances the pumps may be driven by separate motorsof a synchronous type or otherwise operated at the same speed,`but in any event the dispressurey varies irregularly placement of each pump supplies uid to its particular cylinder at such a rate that the rams in all cylinders move at the same uniform speed even though the operating pressures therein may vary Widely at any given instant. 5

Other objects andadvantages will be more apparent to those skilled in the art from the following description of the accompanying drawing in which the gure is a diagrammatic outline of my improved press and control system.

The particular embodiment.l of the invention, which is disclosed herein merely for the purpose of illustrating one specic formfamong possible others that the invention mightv take in practice, comprises any suitable form of press diagram- 15 matically shown at l having a movable press element 2 such as a platen, knife, die or other member. This element is specifically shown as being operatedv by apalr of rams and cylinders 3 and 4 locatedsymmetrically with respect to element v2. A drawback ram and cylinder is diagrammatically indicated at 5 and aA lower normally stationary opposed platen is providedat l. For purposes of simplicity', the .elements 2y and 6'v regardless of whether the lsame are die patens, knives or other devices', will be all hereinafter referred to as naemc The operating mechanism for the rams 3 and l comprises positive displacement pumps 1 and 8 simultaneously driven preferably by a common motor 9 so as' to positively displace identical quantities ofllquid, although it will of course be understood that if for any reason' it is desired to have rams 3 andy 4' of different diameters', then one or the other of the pumps would have a correspondingly reduced or enlarged capacity, but in either. case the amount of iiuid displaced by the l individual pumps is inproportion to the operating rams so as to compel uniform movement thereof regardless of varying pressures that may be required simultaneously in the different cylinders to overcome varying forces resisting platen movement. The control and supply of liquid from the pumps to the ram cylinders 3 and 4 is through similar systems and hence it is only necessary to describe the apparatus for one of the same except when it is otherwise desirable to refer tothe apparatus for both cylinders', the corresponding parts for the other cylinder having the same reference numbers, primed.

With the apparatus in the position as shown, platen 2 is held in its upper position by liquid locked in drawback cylinder 5, To initiate downward movement of the platen, control valves I0 and I0' are simultaneously moved outwardly by their intended purpose.

lo and In' pull-back cylinder 5 as through pipes I2, I1 and tendency of wardl movement would be'only very slight and `the platen,

v its own pressure as may the. platen in its upper position. u

any suitable operating mechanism such as a servo-motor IIa which operates a linkage generally indicated at II, Fluid pressure thus ows from pumps-1 and 8 to the cylinders, for example, from pump 1 through pipe I2, valve Ill, pipe I4 and pipes I5 and 22 to grammatically shown and may take any 'of the usual forms in actual practice for accomplishing The direction of normal ow through the various check valves is indicated by arrows adjacent thereto. As fluid is exhausted from the drawback cylinder 5, platen 2 and its rams will lower substantially by gravity without resistance and hence a large volume of low pressure uid may be supplied from tank I9 to the cylinders, for example, through pipe andfhorizontal pipe 20a, a check valve 2| and passage 22 to cylinder 3. So long as, the 'platen moves freely downwardly without resistance, there will be no tendency for it to tilt, and hence the main ram cylinders 3A and 4 will be lfreely and equally supplied with low pressure liquid from the filling tank. Inasmuch as the pumps are also supplying fluid to the cylinders simultaneously with the supply from the filling tank, it will be seen that, instantly when movement of the platen slows down to the point where 'the pumps alone can supply liquid to the cylinders, then the pumps will increase the pressure in the cylinders and. also vclose check valves 2I and 2|. The equal supply of fluid from both pumps will cause a uniform rate of platen movement regardless of varying countered simultaneously at different points of such variations in vresistance being that each pump can develop be required to overcome the resistance adjacent itsv particular ram.

compensated for in It will also be understood that downward movement of platen 2 istcontrolled by the rate of discharge of liquid from drawback cylinder 5 through valves I0 and Ill so that if necessary under certain special circumstances, vthe movement of the platen may be slowed down by the check valves `2I andf2I before platen'2 engages the work,

control valves toinsure closure of and thus permit pumps 1 and 8 to `constitute the sole supply just before platen 2 engagesfthe work piece.

vWhenfull downward movement of platen 2 has been completed, the operator reverses valves so as to admit pump pressure to the4 I6'. At the same time this pumprpressure is transmitted, for example, to a cylinder" 23 for raising check valve 2| by a plunger 23a. 'and permitting reverse flow of liquid from cylinder 3through pipes 22, 20a and 20 to tank I9.

When the platen is raised to its uppermost position, the operator returns control valves I0 and I0' totheir neutral position as shown in the figure, thereby closing 'passages I1 and I1' to lock liquid in drawback cylinder 5 and hold From the foregoing disclosure it is seen.- that I have provided a very effective system lfor .com- 'pelling uniform 'movement of platen 2. Any

the platen to tilt during its downmomenta'rily because the pump pressures would immediately automatically'vary so as to exert f dependent 4pressures with an intensier cylinder resistance that may be en-v exhaust. Check valves 45 and 45' a greater force on the lagging prtion of the platen and thus return the platen to its horizontal position. The variationsv in pressure would at all times be accompanied by a uniform displacement of liquid from the pumps and hence the platen cannot be forced out of alignment by such variations in pressures into alignment in the event of any tendency to tilt. It will .of course be understood that any tendency to tilt would not be appreciable in actual practice ancLthaLit-weuld be well within the clearancetolerance of the usual platen guides. If it is desired to employ intensier means, I have provided two similar intensifier systems, one for each pump and cylinder, adapted to have inbut coordinated in their operation. For example, when valves I0 and I0 admit pump pressure topipes I3 and I3 to'initiate down,A movement of the platen, fluid is also transmited through pipes 30, 33 and 30', 33' to both ends of a shuttle valve 34. -If pressure is greatest in line 30, then valve 34 is shifted to the left and vice versa if pressure is greatest in line The shuttle valve thus prevents uid from one pumping system iiowing into the other pumping system in case unequal pressures should occur therein and yet the shuttle valve will insure simultaneous operation of both ntensier systems regardless of the existence of unequal pressures. This last function of simultaneous operof either pump reaches `a predetermined value, it is transmitted through a pipe 35 to raise a three spool piston valve 36 against an adjustable spring 36' and simultaneously connect pump1 31 and connect pump 8 with an intensifier cylinder 31'. 'Ihese connections are respectively made through pipes 30,

but can be forced 38, valve 36 and ;pipe3ll; and pipes 30' and 40,

vvalve 36 and pipe 4I.v The two intensifier systems are thus simultaneously operated to cause high pressure plungers 43 and 43' thereof to discharge identical quantitiesof fluid through pipes 44 and 44 and check valves 45 and 45'vtov the main ram cylinders 3 and 4. This intensied pressures -closes check valves I4 and I4' thus causing the equal displacement be ,transmited to their respective intensifier systems and compel equal and uniform displacement 'of liquid therefrom to the main cylinders regardl less of pressure uctuations therein. The intenfrom both pumps to.

sifier pressure also closes check valves 46 and 46 in pipes 41 and 41', these valves and pipe connections normally permitting fiuid to be supplied from sump I9 to the high pressure side of the intensifier system during downward movement of the intensifier plungers. When control valves I0 and I0' are moved inwardlyto raise the platen, fluid from the large intensifier cylinder 31y is discharged back through pipe 39, a check valve 5|! and pipes 30 and 24 to sump I9. similarly uuid from the intensifier cylinder 31 is discharged back through pipe 4I, checkvalve 50 and pipes 30' and 24' to the sump.- Check valves 45I! and 50' are necessary in accomplishing the 4foregoing operation because valve 36 returns to its closed position when pipes 30 and 30 are connected to prevent flow of pump fluid through pipes 44 and 44: at .the time when the pumps alone are inially supplying fluid through pipes I5 and I5' to the main ram cylinders. v

The foregoingint'ensier system-will uniformly supply equal quantities of fluid to'the main ram cylinders by reason of the large cylinders of the 30 ation is accomplished in that when the pressure f.

intensiers being uniformly and simultaneously supplied with equal quantities of fiuid from the two pumps. Also these intensifier systems are rendered operative automatically only when the pump pressure reaches a predetermined value. as determined by the adjustment of spring 36.

Briefly summarized, the sequence of operations is as follows: With the control valves I and I0' in neutral position, liquid is locked in drawback cylinder to hold platen 2 in its upper position. The platen is moved downwardly by shifting control valves I0 and I Il' outwardly, thereby exhausting fluid from the drawback cylinder to permit downward platen movement. A large volume of low pressure fluid is supplied fromiilling tank I9, past check valves 2I and 2 I and through pipes 22 and 22' to the main cylinders 3 and 4 during initial downward platen movement. Simultaneously therewith iiuid is supplied from pumps 'l and 8 through pipes I2, I2', I5 and I5' so that when platen movement requires higher pressure,

-then the pump pressure lwill automatically build up and continue movement of the platen, the filling tank check valves 2I and 2l automaticallyclosing. The pumpsvwill, therefore, supply uniform quantities of fluid to each main cylinder 3 and 4 and compel uniform movement thereof regardless of pressure fluctuations that may simultaneously exist in said cylinders. To reverse the platen, valves I0 and I0' are shifted inwardly to supply pump pressure through pipes I1 and I6 'to the pull-back cylinder 5 and at the same time supply fluid to cylinders 23 and 23 to open check valves 2| and 2| and thus permit fluid from the main ram cylinders 3 and 4' to be freely returned to the sumpthrough pipes 22, 22', 20a and 20. If

. the pressure intensifying means are desired to o changes in details of construction and arrangebe used, then spring 36 -is adjusted to suitably open at a predetermined pump pressure transmitted through pipes 30 and 30' and thereby simultaneously and uniformly operate the intensiners. Any usual threaded stem 36a screwed into the valvehousing as shown may be employed to Jadjust the spring of valve 36 or other valves shown at various points of the.system, and hence it is possible to render the intensier means inoperative. merely by holding valves 36 closed at all times.

From the disclosure herein it is seen that I have provided an improved combination of a press and operating means therefor whereby uniform platen movement is positively hydraulically effected in an eiiicient and simple manner, thereby permiting the press structure and operating system tobe manufactured and operatedin an economical manner without the necessity of providing a. physical structureof abnormal size or strength such as vmight be required with prior arrangements.

It will of coursebe understood that various ment of parts may be made by those skilled in the art without departing from the spirit of the invention as set forth in the appended claims.

I claim: n

1. A hydraulic vpress comprising, in combination, a platen, a plurality of cylinders and rams simultaneously operative to move said platen, a plurality of commonly operated positive displacement hydraulic pumps one for each of said cylinders, said pumps being of such volumetric displacement and the cylinders respectively connected thereto being of such diameter that uniform operation 'of said pumps insures uniform a movement of said platen, a plurality of control valves one between each pump and its cylinder, and means for simultaneously operating said valves to insure simultaneous communication between each pump and its respective cylinder.

2. A lhydraulic press comprising, in combination, a platen, a plurality of cylinders and rams simultaneously operative to move said platen, a plurality of positive displacement pumps one for each of said cylinders, and rotary means for commonly mechanically driving said pumps at the same speed, `said pumps being of such volumetric displacement and the cylinders respectively connected thereto being of such diameter that uniform movement of said platen occurs regardless of varying degrees' of resistance, to the movement of said platen, that may exist simultaneously at different points thereon.

3. A hydraulic press comprising, in combination, a platen, a plurality of main cylinders and rams simultaneously operative to move the platen, a plurality of commonly 'actuated positive displacement pumps respectively having substantially uniform volumetric displacements under varying pressures; said cylinders being connectible with said pumps and of such diameters that substantial uniform movement of said platen' occurs, a pullback cylinder and ram, a plurality of simultaneously operative valves for simultaneously establishing communication between said pumps and their respective main cylinders or for releasing fluid therefrom, and valve mechanism controlled by said plurality of valves thereby to establish communication between said pump and said pullback cylinder.

4. A'hydraulic press comprising, in combination,l a platen, a plurality of cylinders and rams simultaneously operative to move the platen, means for supplying low pressure liquid to said cylinders during initial movement of said rams, pumping means for additionally supplying liquid to said cylinders at a uniform rate independently of pressure uctuations in the respective cylinders, a` plurality of control valves one between each of -said cylinders and said pumping means, and means for simultaneously operating said valves to insure simultaneous communication between said pumping means and said cylinders.

5. A hydraulic press comprising, in combination, a platen, a plurality of cylinders and rams `simultaneously operative lto move the platen,

pumping means, means for simultaneously operating said valves to insure simultaneous communication ybetween said pumping means and said cylinders, and means for discontinuing said low pressure supply of liquid automatically when' the rate of movement oi the rams is such that the high pressure uid can maintain said movement.

6. .A hydraulic press comprising, in combina-l tion, a platen, a plurality of main cylinders -and rams simultaneously operative to move the platen,

means for supplying low pressure liquid to said 1 cylinders during initial movement of said rams, pumping means for supplying high pressure liquid to said cylinders ata uniform rate independently of pressure fluctuations in their respective cylinders, a. plurality of control valves one between each of said cylinders and said pumping means, means for simultaneously operating said valves to insure simultaneous communication loe=l tween said pumping means and said cylinders, means for discontinuing said low pressure supply of liquid automatically when the rate oi movement of the rams is such that the high pressure liquid can maintain said movement, a pullloaclrn cylinder and ram, andmeans for releasing the high pressure liquid in said main cylinders and for supplying fluid from said pumping means to said pullback cylinder to reverse the movement of said platen.

'7. A hydraulic press comprising, in combina.- tion, a platen, a plurality of cylinders and rams simultaneously operative to move the platen, means for supplying low pressure liquid to said cylinders during initial movement of said rams, pumping means for supplying high pressure liquid to said cylinders at a uniform rate independently of pressure fluctuations in their respective cylinders, a plurality of control valves one hetween ,each of said cylinders and said. pumping means, means for simultaneously operating said valves to insure simultaneous-communication between said pumping means and said cylinders, means for-discontinuing said low pressure supply of liquid automatically when the rate of movement oi the rams is such that the high pressure liquid can maintain said movement, means for reversing the movement of said platen, and means for discharging a large volume of fluid from said cylinders at a relatively low pressure during said reversing movement.l

8. A hydraulic press comprising, in combinaardesia tion, a platen, a plurahty oi cylinders and rams simultaneously operative to move said platen, a lling tanls, means for coonly supplying said cylinders Withlovv pressure liquid rcinsaid lling tank during initial movement of said rams, a plurality of pins having uniform rates oi dispiacement for separately supplying high pressure opm erating liquid .individually to said cylinders, a plurality of control valves one between each pump and its cylinder, means for simultaneously operating said valves to insure simultaneous communication between each pump and its respective cylinder, and means operated by vsaid pump pressure for discontinuing said low pressure liquid supply automatically when the high pressure supply is initiated. v

9. The combination set forth in claim l further characterized by the provision of pressure intensifier means operative to discharge liquid at a uniform rate when uniformly actuated, means for uniformly actuating said intensier means by a constant rate of supply of liquid from said pumps, and means for supplying liquid to the press cylinders from said intensifier means.

10. The combination set forth in claim iiurther characterized by the provision of pressure intensifying means operated by said pumps for uniformly supplying liquid to said cylinders from said intensified means, and means for automat ically rendering said intensifier means operative only after the pressure of the pumps reaches a predetermined value. e

RICHARD W, DINZL.

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