US2358650A - Hydraulic press - Google Patents

Description

HYDRAULIC PRESS Filed Oct. 7, 194i 4 Sheets-Sheet l 14 I is 96 mvzu roa 66 70 JHNIAUDE ATTO R N EYS I Sept. 19,1944.

J. H. MAU DE HYDRAULIC PRESS 4 Sheets-Sheet 2 Filed Oct. 7, 1941 R MS 3% mlwm mm m Maw Sept. 19, 1944. J. H. MAUDE HYDRAULIC PRESS Filed Oct. 7, 1941 4 Sheets-Sheet 3 Sept. 19, 1944. H. MAUDE 2,358,650

HYDRAUL I C PRES S Filed Oct. 7, 1941 4 Sheets-Sheet 4 INVENTOR WM M ATTOR N Patented Sept. 19, 1944 i BAULIO PRESS John H. Maude, Verdun, Quebec, Canada, assignor to Dominion Engineering Works limited,

Lachine, Quebec,

Application October 7, 1941, Serial No.- 414,004

7 Claims. (01. 121-38) This invention resides primarily, in the provision of means for speeding up the pressing cycle of hydraulic presses and is particularly useful in connection with high speed presses in which a preflll valve is provided to facilitate rapid flow of fluid from a storage tank to the pressing cylinder during a working stroke of the pressing ram and rapid return of the fluid from the pressing cylinder tothe storage tank during the return stroke of the ram. In such presses the time required to complete the pressing cycle is substantially reduced by the rapid filling and emptying of the pressing cylinder which is made possible by the relatively large flow passage which the prefill valve provides between the pressing cylinder and the storage tank. However, with the presses and control mechanisms now available it is not possible to take full advantage of the I maximum extent to which the power stroke of the movable ram or die of the press may be speeded up by improving the design of the preflll valve since this would result in the platen or die coming in contact with the work while travelling at such a highrate of speed as'to impose severe shock stresses on the work or on the working parts or the press.

With the foregoing in mind an important feature of the invention resides in the provision of means for controlling the operation of the press so that the movable die or platen is caused to travel at an exceptionally high rate of speed during the idling portion of the power stroke and is then slowed down so that it contacts the work while travelling at the proper pressing speed. In this way the maximum speeding up effects obtainable by improvements in the design of preflll valves may be utilized without danger of subiecting the work or press to excessive shock damage due to the movable platen or die coming in contact with the work while travelling at an excessive rate of speed.

In the preferred embodiment of this invention the rate of speed at which the movable platen iii-om the push back space of tlie pressing cylin- Another feature of the invention resides in the provision 0! a novel cam mechanism for operating the slow down valve in properly timed relation to the movement of the movable die or platen.

Another feature of the invention resides in the provision of a cam. mechanism including cams which, in addition to controlling the action of the slow down valve, also control the operation of the main working or reversing valve through which pressure is alternately supplied to and exhausted from the pressing and push back chambers of the cylinder containing the ram which operates the platen or die.

Another feature of the invention resides in the provision of a novel cam mechanism which, while particularly useful for operating the pre- Jviously mentioned slow down valve,- is also intended for general application in connection with or die travels during the power stroke of the press is controlled by. a "slow down valve which is held open to permit the platen or die to move at maximum speed imtil the dieor platen ap-- proaches within a predetermined distance of the work, whereupon the valveis partially closed to slow down the platen or die so that it completes the idle portion of its pressing stroke and meets the work while travelling at the predetermined pressing speed. The "slow down valve is preferably interposed in a pressure fluid line through which pressure fluid is supplied to and exhausted hydraulic presses and in any other relations in which it may usefully be employed.

Other features and advantages of the invention will be more readily imderstood from the following detailed description and accompanying drawings, in which- Fig. 1 is a diagrammatic view illustrating the application of my inventlonto a hydraulic press.

Figs. 2 and 3 are diagrammatic views illustrating dlilerent working positions'of the cam mechanism which controls the operation of the slow down valve.

Figs. 4, 5 and 6 are diagrammatic views illustrating different operating positions of a cam and toggle mechanism which controls the operation of the main working or reversing valve.

Fig. '1 is a diagrammatic view illustrating the manner in which the cam controlling the operation of the main working or reversing valve cooperates with the cam controlling the slow down valve to eiiect the resetting of the slow down valve after eaclroperatlon thereof.

Fig. 8 is a vertical sectional view illustrating a preferred construction and assembly of the component parts of the cam mechanism provided for controlling the slow down valve and the main working or rev'erslngvalve. v

Fig. 9 is a sectional view taken substantially along the line 98 of Fig. 8, In this view the reversing cam is shown rotated through an angle of approximately from the position shown in Fig. 8.

Fig. 10 is an enlarged detail view of a portion of the-cam which controls the main working or reversing valve and Fig. 11 is a side elevation ofthe cam portion appearing in Fig. 10.

In the present drawings I have shown only those parts of a hydraulic presswhich are necessary to an understanding of my invention. Such parts comprise the movable platen 5, main cylinder 6, preflll valve 1, preflll tank 8, pump 9, pump driving motor I D, storage tank II and the main working or reversing valve assembly l2. Platen is carried by the main ram l8 which divides cylinder 5 into an upper pressing chamber I4 and a lower push back chamber 8. In the present instance I have shown a preflll valve I of the type described and claimed in the co-pending application of W. P. Muir and J. H. Maude, flied July 6, 1938, under Ser. No. 216,318, now abandoned. Since this valve .is fully described in said co-pending application the following brief reference thereto is deemed sufllcient for present purposes.

The movable valve member I8 is urged to its seat by the valve closing spring Ila. Located directly above the valve stem I8 is a pressure operated plunger 2| which is normally held in a raised position by a spring 22 acting against a piston head 28 provided at the upper end of the plunger. When ram l8 commences to move downwardly on its working stroke valve l8 opens automatically against the resistance of spring |8a to permit flow of fluid from tank 8 to the upper end of cylinder 8. During the working stroke of ram IS the preflll valve l8 remains open until further downward movement of the platen closed by the increased pressure developed in the pressing chamber l4, when the platen 5 or the pressing die carried by the platen comes in contact with the work. Y

When valve member 28 is shifted to the return stroke position shown in Figs. 4 and 5 pressure fluid is pumped to the push back chamber I8 through the supply line 85a, ports 82, 80 and 85 and line 26. At the same time part of the fluid 5 is resisted by engagement with the work. The

resulting rise in pressure in cylinder M, to which fluid pressure is being pumped through line 25, causes valve I6 to close against its seat I! and to remain closed until the movable valve member of the main control valve assembly I2 is shifted to a return stroke position. When this occurs part of the pressure fluid supplied to the push back chamber l8 through the fluid pressure line 25 passes through line 24 and serves to force the piston 28 and plunger 2| downwardly to open valve l6 so that during the return stroke of the ram l3 part of the fluid previously supplied to the pressing chamber I4 is returned to the tank 8. This operation of the preflll valve I will be more clearly understood from the following description of the construction and operation of the main working valve |2.

As here shown the main working valve assembly l2 comprises a valve member 28 working in a valve casing 28. Member 28 is provided with an annular port 88 and a fulllength axial port 8|. These ports cooperate with the valve casing ports 82, 88, 84 and 85 in the following manner.

When valve member 28 .is in the position shown in Fig. 1 pressure fluid is pumped to the main pressing chamber l4 from the pressure side of pump 9 through supply line 85a, ports 82, 88 and 84 and line 25. At the same time fluid previously supplied to the push back chamber I8 is exhausted from said chamber through line 28, ports 35, 3|, 88 and line 88 to the sump storage tank II. In this position of valve 28 a working stroke of the press ram I8 is effected by the pressure fluid supplied to the pressing cylinder |4. As previously stated the preilll valve 1 opens during the downward movement of the ram l8 to ensure a rapid fllling of the pressing chamber N, the preflll valve remaining open until it is forced previously supplied to the pressing chamber I4 is exhausted therefrom through line 25, upper part 01' valve casing 28 and line 88. In this position of valve member 28 a return stroke of the pressing ram I8 is eil'ected by the pressure fluid supplied to the push back chamber l8 and a part of this pressure fluid is diverted. as previously described, through line 24 to hold the preflll valve I open so that part of the fluid previously supplied to the pressure chamber I4 is permitted to pass rapidly into the preilll tank 8.

Valve member 28 is secured to the upper end of an operating plunger 88. The lower end 01' this plunger is connected by toggle links 88 and 48 to a toggle arm 4| formed integral with a manually operable valve actuating lever 42. The lever 42 is loosely mounted on a pivot shaft 48 contained in the lower portion of box 44. Link 48 is provided with a shaped stop 45 which engages a similar stop 48 of link 89 to prevent further anti-clcckwise rotation of the latter about the connecting pin." when said links are disposed in the position shown in Fig. 1. In the position shown in Fig. l clockwi..e movement of toggle arm 4| of lever 42 from the substantially vertical position shown is prevented by engagement oi. lever 42 with the lower end of the lever slot 44a provided in the control box 44.

When the press is making a power stroke the valve member 28, plunger 88, toggle links 88 and 40, toggle arm 4| and lever 42 are positioned as shown in Fig. 1. In this position of the parts the two links 89 and become, in eifect, a single rigid link by reason of the fact that the shaped stop 45 on link 40 is engaged with the shaped stop 48 on link 88 to preventfurther anti-clockwise rotation of link 88 with respect to link 40. Consequently (considering links 89 and 40 as one rigid link in a toggle system having one end pivot at shaft 48 and the other end pivot at the pin 49 connecting plunger 88 with the upper end of link 88) it will be seen that with the toggle arm 4| in the vertical position shown in Fig. 1 the toggle system will be locked against collapse because the pin connection 58 between link 48 and toggle arm 4| is positioned to the right of the center line between shaft 48 and pin 49, it being remembered that lever 42 is held against further clockwise movement by the lower end of the lever slot 44a and that stops 45 and 48 are holding link 89 against further anti-clockwise movement relative to links 48. A trip lever 52 is loosely mounted .on an intermediate pivot shaft 58 contained in the box 44. The upper end of lever 82 is positioned opposite the pin connection 41 between the links 89 and 48 while the lower end of said lever is positioned to be engaged by the inner end of a horizontally slidable tappet rod 58a. Tappet rod 58a is slidably mounted in casing 44 in any suitable manner so that the outer end portion of said rod passes outwardly through the wall of the casing and is disposed in the path of movement of the arm 54 01' a bell crank lever 55 which is pivoted to a suitable bracket 58. The remaining arm 51 of the bell crank lever is connected tothe upper end of a link 58 the lower assaeso end of which is adiustably connected asat 99 to one end of a cam operated lever 99. The cam operated lever 99 is mounted to swing about a pivot 9| and carries a roller 92 which rides the surface of a reversing cam 99. (Jam 99 is fixed to rotate with a shaft 99 which is driven by gears 99, 91, 99 from a rack 99 carried by and movable with the platen s.

when the ram l9 has completed its power stroke, or a predetermined portion thereof, as determined by the setting of the cam 99, the lift portion 19 of said cam engages the roller 92 and lifts the free end of the link 99. The resulting upward movement of link 99 moves the bell crank lever 99 in a clockwise direction so that the arm 99 of the bell crank lever against the tappet rod 590 to move the latter to the right against the --lower end of lever 92. The upper end of lever 52 is thus swung to the left and acts to shift the pivotal connection 91 between the links 99 and 99 to the left of the center line between the shaft 99 and the toggle pin' 99 (see Fig. 6). The toggle links 99 and 99 then collapse to the position shown in Fig. 4 permitting the valve 29 to move downwardly from the power stroke position shown .in Fig. 1 to the return stroke position shown in Figs. 4 and 5. The instant at which the toggle links are collapsed to permit shifting of valve 29 from the position shown in Fig. 1 to the position shown in Figs. 4 and 5 may be varied in relation to the power stroke of the ram i9 by changing the angular setting of the cam 93 as hereinafter described.

The shifting of the valve member 29 from the return stroke position shown in Figs. 4 and 5 to the power stroke position shown in Fig. 1 may be accomplished in the following manner: With the parts in the position shown in Fig. 4 the lever 92 is first-raised to shift the toggle arm 9| and the links '99 and 90 to the position shown in Fig. 5. With the parts in this new position lever 92 is then swung downwardly to sucessively shift the arm 9| and the links 99 and 99 to the position shown in Fig. 6. During this last motion plunger 99 and valve 28 are moved of the fact that the shaped stops 99 and 99 prevent iurther counterclockwise rotation of link 99 with reference to link 49. In connection with this resetting of the toggle mechanism it will be understood that the lever 52, tappet rod 99a.

bell crank 59, link 59 and cam operated lever 99 resume the position shown in Fig. 1 as soon as th cam lift 10 passes beyond the roller 92.

The slow down valve provided in accordance with this invention comprises a valve member 12 working in a valve casing I9 included in the fluid line 29. Valve member 12 is normally held in a fully open position by a spring 19a working against the valve stem 19. As long as this valve remains open'duringthe power stroke of the ram H, the exhaust of fluid from the push back casing i9 via fluid line 29 is unobstructed and permits the ram l9 to descend at maximum speed. At a suitable instant .prior to engagement of the work by the platen 9 or the tool carried thereby the valve 12 is shifted from the fully open position shown in Firs. 1 and 2 to the throttling or partially closed position shown in Fig. 3. In this latter position of valve 12 the flow of fluid from the push back chamber i9 through the valve casing 19 is throttled down so that the descending speed of the ram l9 and the platen 9 is sufiiclently reduced so that the platen 9 or the tool carried thereby is brought in contact with the work while traveling at Pressing speed. The shifting of the valve 12 from the position shown in Fig. 1 to-the position shown in Fig. 3 is accomplished through the agency of the control cam mechanism. generally indicated at 19. This mechanism includes a bell crank lever 11 pivoted to a bracket portion 59 r of the valve casing I9. One arm 19 of lever 11 is fitted in a groove 99 provided in the valve The other arm 9| of lever 11 is connectedbyalinkfltothefreeendofaca'm operated lever 99, the remaining end of the last mentioned lever being pivoted as indicated at 99. Lever 99 is provided with a stop 99 and with a pair of swinging links 91 the latter having their upper ends pivoted to opponte sides of the lever. A roller 99 is carried between the lower ends of links 91 and is disposed to ride the edge of cam 99 which is driven from the same shaft 99 which drives the reversing cam '99. During part of the power stroke of the ram the lever 99, links 91, roller 99 and cam 99 are in the position shown in Fig. 1, the slow down valve 12 being open. As the cam 89 is rotated (in the direction indicated by the arrow) from the position shown in Fig. 1 to the position .shown in Fig. 2, the roller 98 drops into the cam recess 9|, the links 91 being prevented from swinging beyond the vertical position shown in Fig. 2 by engagement of said links with the stop 99. As the cam 99 continues to rotate from the position shown in Fig. 2 to the position 'shown in Fig. 3 the roller 99 rides on the lift in Fig. 3. The particular instant, in relation to the power stroke of the ram l9. at which the slow down valve 12 is shifted from the position shown in Fig. 2 to the position shown in Fig. 3 may be varied by changing the angular position of the cam 99 as hereinafter explained. The lift portion 19 of the reversing cam 99 is provided with a laterally extending arm 99 compare Figs. 1. 8. 10 and 1-1. when the lift portion "of cam 99 is rotated from the position shown in Fig. 1 to and beyond the valve reversing position shown in Figs. 4 and 'l the arm 99 thereof en ages a projection 91 of one of the' links 91 (Fi s. 7 and 8) so that the links 91 and the roller 99 are swung back to the position shown in Fig. 1 thus permitting lowering or resetting of the lever 99 to return the slow down valve 1! to its normally fully open position. when valve I2 is butted against the left hand end of cylinder 19. as shown in Fig. 1, the lever 99 is prevented from dropping below the podtlon shown in this flszure by the link 92.

In Figs. 8 and 9 I have shown'what I now con. sider to be the preferred mechanical assembly of the component parts of the cam mechanism diarammatically. illustrated in Fig. 1. As here shown the central ortion of shaft 99 is iourthe casing wall ill and the bracket portion IN, the gear ll being keyed to shaft I in mesh with the gear 61 which is keyed to a shaft i! which also carries the gear 00 and, which is ioumalled in suitable bearings Ill and ill.

Cam '3 is clamped in place between the shoulr "a of shaft 85 and a clamping plate Ill. w ich is jammed against a friction facing ill L ecured to said cam. The clamping plate It. is p ovided with a hub III which is slidably keyed Kn/to theshaft N. The cam I. is slidably fitted on the hub Ill and is clamped against a friction facing N2 of the clamping plate MI by means of a clamping nut H! which is threaded onto the free end of hub II I. A second clamping nut III When it is desired to change the angular displacement of cam 63 this may be conveniently accomplished by loosening the clamping nut ill suiiiciently to permit cam II to be turned about shaft 85. When it is desired to change the angular displacement of the cam 89 this is accomplished by loosening the clamping nut ill willciently to permit said cam to be turned about the supporting hub Ill. The clamping plate I! may be graduated asindicated at H! in Fig. ,9 to facilitate duplication of any particular angular setting thereof.

While the cam mechanism illustrated in Figs. 8 to 11 inclusive was developed for and is particularly useful in connection with the purposes of the present invention, it is obvious that such mechanism is capable of general application in connection with hydraulic presses and in various other relations. For example, such mechanism may be used in connection with any form of control valve to prescribe the exact instant at which pressure fluid may be ported, through the valve, to any desired point. There are certain types of pressesin which, at a certain stage in the stroke of the down stroking rams, it is desired to impart an up-stroke to auxiliary rams in the press space. The cam mechanism shown in the present application may be used in conjunction with suit- .able valves to control the exact instant at which pressure fluid is supplied to the auxiliary rams to move them on the up-stroke.

The foregoing are only a few of the many instances which may be cited with reference to the general utilization of. the cam mechanism in question.

Having thus described what I now conceive to be the preferred embodiment of this invention it will be understood that various modifications may be resorted to within the scope and spirit of the appended claims. I

Having thus described my invention, what vI claim is:

1. A hydraulic press comprising a cylinder, a ram working therein, means for applying working fluid pressure to move said ram in a power stroke direction against an opposing iluid pressure established in said cylinder, a throttle valve through which said opposingiluid pressure is discharged from the cylinder during the aforesaid movement of the ram, means normally holding said valve in afully opened position, and ram- .actuated means for operating said valve to throtsaid cylinder when the ram has moved ante determined distance on its power stroke, said last mentioned means comprising a rotary cam driven remaining ends of said links and arranged to ride the periphery of said cam, said links being held in an inclined position with reference to the lever when said roller is riding a portionof the cam which is of maximum radius but being adapted to assume a position normal to said lever when another portion of the cam which is of minimum radius is'rotated to a position beneath said roller, said cam being contoured so that, following engagement of the roller with the cam portion of minimum radius, portions of the cam of gradually increasing radius from the minimum to the maximum are rotated into contact with the roller to effect a predetermined-movement of said links and lever.

2. A construction as set forth in claim 1 including ram-actuated means for automatically swingcluding a. cam shaft mounting and driving said cam and a member rotatable with said shaft and adapted to engage a portion of one of said links for swinging the latter'back to their original inclined position to permit the lever to drop down to its normal position subsequent to the operation of the said valve, said cam and said member being adjustable about said shaft to vary the angular displacement thereof.

' 4. A construction as set forth in claim 1 including a cam shaft mounting and driving said cam .and a member rotatable with said shaft and adapted to engage a portion of one of said links for swinging the latter back to their original inclined position to pemiit the lever to drop down to its normal position subsequent to the'operation of the said valve.

5. A construction as set forth in claim 1 in which the first mentioned means includes a reversing valve operable to a power stroke position in which fluid pressure is routed through said valve to move said ram in a power stroke direction or to a return stroke position in which fluid pressure is routed through said valve to move said ram in a return stroke direction, means for operating said reversing valve'to its power stroke position, a ram-actuated cam shaft mounting and driving said cam, a reversing valve operating member rotatable with said shaft and means actuated by said member for operating the reversing valve to areturn stroke position when theram has travelled a'predetermined distance in the power-stroke direction.

6: A hydraulic press comprising a cylindenja ram working therein, a reversing valve operable to a power stroke position in which fluid pressure is routed through said valve to move said ram in a power stroke direction against an opposing fluid pressure established in said cylinder, said valve being also operable to a return stroke position in which iiuid pressure is routed theretle the discharge of said 01 9.08 1 8- p 'c fe f m 16 .tle valve in fully open position-and ram-actuated cam mechanism functioning, during the power stroke of said ram, to operate said throttle valve to throttle the discharge of said opposing pressure from said cylinder when the ram has moved a predetermined distance on its power stroke; to operate said reversing, valve to its return stroke position at a predetermined instant subsequent to the aforesaid operation of the throttle valve; and to reset the throttle valve at a predetermined instant, said, cam mechanism comprising a pair of cams actuated by said ram, resettable means operable by one of said cams to effect the aforesaid operation of the throttlevalve to a throttling position and means controlled by the other cam for operating the reversing valve to its return stroke position and resetting the resettable cam operated throttle valve operating means.

7. A hydraulic press comprising a cylinder, a ram working therein, a reversing valve operable to a power stroke position in which fluid pressure is routed through said valve to move said ram in a power stroke direction against an opposing fluid pressure established in said cylinder, said valve being also operable to a return stroke position in which fluid pressure is routed therethrough to effect a return stroke of the ram, a throttle valve through which said opposing fluid pressure is discharged from the cylinder during the power stroke of the ram, means for operating said reversing valve to its power stroke position, means for normally holding said throttle valve in a fully open position, a cam shaft driven by said ram, a throttle valve controlling cam flxed to rotate with said shaft, a reversing valve controlling cam also fixed to ro-' tate with said shaft, a pivotally mounted throttle valve actuating lever, a pair of links having corresponding ends pivoted to said lever, a cam riding roller carried between the remaining ends of said links and arranged to ride the periphery of said throttle valve cam, said links being held in an inclined position with reference to the lever when said roller is riding a portion of the throttle valve cam which is of maximum radius but being adapted to assume a position normal to said lever when another portion of the throttle valve cam which is of minimum radius is rotated to a position beneath said roller, said throttle valve cam being contoured so that, following engagement of the roller with the cam portion of minimum radius, portions of the cam of gradually increasing radius from the minimum to the maximum are rotated in contact with the roller to efiect a predetermined movement of said links and lever, whereby said throttle valve is moved to throttle the discharge of said opposing pressure from said cylinder when the ram has moved a predetermined distance on its power stroke, means actuated by the reversing valve cam to operate the reversing valve to a return stroke position subsequent to the aforesaid operation of the throttle valve to its throttling position and means carried by the reversing valve cam for resetting the lever and links of the throttle valve operating mechanism.

JOHN H. MAUDE.

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