US2358759A - Hydraulic press - Google Patents

Description

Sept; 19, 1944. M U 2,358,759

HYDRAULIC "PREss Original Filed Oct. 7, 1941 4 Sheets-Shea? 1 mvEm'oR FIGJ g;

ATTORN Sept. 19, 1944. J. H. MAUDE 2,358,759

' HYDRAULIC PRESS Original Filed 0012.7, 1941 4 Sheets-Sheet 2 INVENTOR JJ-LMAUDE B mmfiagmh ATTORNE Sept. 19, 1944. J. H. MAUDE HYIDRAULIC PRESS Original Filed 001;. 7, 1941 4 Sheets-Sheet 5 INVEINTOR 4 J-HJIA as ATTORN max J. H. MAUDE 2,358,759

HYDRAULIC PRESS Sept. 19, 1944.

Original Filed Oct. 7, 1941 4 Sheets-Sheet 4 I 101 mvswron JJ-LMAUDE Patented Sept. 19, 19 44 or to Dominion Engineering Works Lachine, Quebec, Canada Limited,

Original application October 7,1941, Serial No 414,004. Divided and this application December 21, 1942, Serial No. 469,775. In Canada October 11, 1941 '7 Claims.

Thisdnvention 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 prefillvalve 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 to the storagetank during the re'- turn 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. How ever, with the presses and control mechanisms now available it is not possible to take full ad vantage of the 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 prefill valve since this would result in the platen or die coming in contact with the work while travelling at such a high rate of speed as to impose severe shock stresses on the Work or on the working parts of 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 powerstroke and is then slowed downso 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 prefill valves may be utilized without dangerof subj'ecting the work or press't'o excessive shock damage due to the movable platen or die icoming'in contact with the work while travelling atan excessive rate of speed. c

In the preferred embodiment of this invention the rate of speed at which the movable platen or die travels during the power stroke of the press is controlled by a slow down valve which is held open t'o permit the platen or die to move at maximum speed until the die or platen approaches within a predetermined distance'of the work, whereupon the valve is 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 rprede termined pressing speed. The slowdown valve is preferably interposedin a pressure fluid line through which pressure fluid is supplied to and v ing cylinder.

cowl-54) exhausted from the push back space of the press- Another feature ofthe'invention resides in the provision of. 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 chainbers of the cylinder containing the ram which operates the platen or die. v

Another feature of the invention resides in the provision of a novel cam mechanism which while particularly useful for operating the previously mentioned slow down valveyis also intended for general application in connection with hydraulic presses and in any other relations in which it may usefully be employed.-

The present application is a division of my copending U. S. application Serial No. 414,004, filed October 7th, 1941.

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

Figs. 2 and 3 are diagrammatic. views illustrating different working positions of the cam mechanism which :controls theoperation of the slow down valve.

Figs. 41, 5 and 6 are diagrammatic views illustrating diiferentoperating positions of a cam and toggle mechanism which controls the operation of the main working or reversing valve.

Fig. 7 is a diagrammatic view illustrating the mannerin which the cam controlling the operation of the main workingv or reversing valve cooperates with the cam controlling the slow down valve to effect the resetting of the slow down valve after each operation thereof.

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

Fig. 9 is a sectional view taken substantially along the line 9-9 of'Fig. 8. In this view the reversing cam is shown rotated through an angle Fig. 11 is a. side elevation of the cam'lportion' appearing in Fig. 10.

In the present drawings I have shown only those parts of a hydraulic press which are necessary to an understanding of my invention. Such parts comprise the movable platen 5, main cylinder 6, prefill valve 1, prefill tank 8, pump 9, pump driving motor l0, storage tank II and the main working or reversing valve assembly l2. Platen 5 is carried by the main'ram I3 which divides rcylinder 6 into an upper pressing chamber l4 and a lower push backchamber l8. In the present instance I have shown a prefill valve 1 of the type described and claimed in the co-pending application of W. P. Muir and J. H. Maude, filed June 28,1938 under Serial No. 216,- 318. Since this valve is fully described in said copending application the followingbrief reference thereto is deemed sufficient for present purposes.

The movable valve member I6 is urged to its seat I! by the valve closing spring |8a. Located directly aboveqthe valve stem |9 is a pressure operated plunger 2| which is normally held in a raised position by a spring 22 acting against a piston head 23 provided at the upper end of the plunger. When ram l3 commences to move downwardly on its working stroke valve l6 opens automatically against the resistance of spring |8a to permit flow of fluid from tank 8 to the upper end of cylinder '6. During the working stroke of ram 3 the-prefill valve l6 remains openuntil'further downward movement of the platen 5 is resisted by engagement with the work. The resulting rise in pressure in cylinder l4, to which fluid pressure is being pumped through line 25, causes valve |6 to'close against its seat l1 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 26 passes through line 24 and serves to force the piston 23 and plunger 2| downwardly to open valve l6 so that during the return stroke of the ram 3 part of the fluid previously supplied to the pressing chamber I4 is returned to the tank 8. This operation of the prefill valve! will be more clearly understood from the following de scription of the construction and operation of the main working valve l2.

As here shown the main working valve assem bly I2 comprises a valve member 28 working in a valve casing 29. Member 28 is provided with an annular port 30 and a full length axial port 3|. These ports cooperate with the valve casing ports 32, 33, 34 and 35 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 4 from the pressure side of pump 9 through supply line 35a, ports 32, 30 and 34 and line 25. At the same time fluid previously supplied to the'push back chamber I8 is exhausted from said chamber through line 26, ports 35,

3|, 33 and line 36 to the pump storage tank H. In this position of valve 28 a working stroke of the press ram I3 is effected by the pressure fluid supplied to the pressing cylinder 4. As previously stated the prefill valve 1 opens during the downward movement of the ram 3 to ensure a rapid filling of the pressing chamber 4, the prefill valve remaining open until it is forced 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.

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 l8 through the supply line 35a, ports 32, 30 and 35 and line 26. At the same time part of the fluid previously supplied to the pressing chamber I4 is exhausted therefrom through line 25, upper part of valve casing 29 and line 36. In this pothis plunger is connected by toggle links 39 and 40 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 43 contained in the lower portion of box 44. Link 40 is provided with a shaped stop 45 which engages a similar stop 46 of link 39 to prevent further anti-clockwise rotation of the latter about the connecting pin 41 when said links are disposed in the position shown in Fig. 1. In the position shown in Fig. 1 clockwise movement of toggle arm 4| of lever 42 from the substantially vertical position shown is prevented by engagement of lever 42 with the lower end'of the lever slot 44a provided in the control box 44.

When the press is making a power strok the valve member 28, plunger 38, toggle links 39 and 40, toggle arm 4| and lever 42 are positioned as shown in Fig. 1. In this position of the parts the two links 39 and 40 become, in effect, a single rigid link by reason of the fact that the shaped stop 45 on link 40 is engaged with the shaped stop 46 on link 39 to prevent further anti-clockwise rotation of link 39 with respect to. link 40. Consequently, (considering links 39 and 40 as one rigid link in a toggle system having one end pivot at shaft 43 and the other end pivot at the pin 49 connecting plunger 38 with the upper end of link 39) 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 50 between link 49 and toggle arm 4| is positioned to the right of the center line between shaft 43 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 thatrstops 45 and 46 are holding link 39 against further anti-clockwise movement relative to links 40. A trip lever 52. is loosely mounted on an intermediate pivot shaft 53 contained in the box 44. The upper end of lever 52 is positioned opposite the pin connection 41 between the links 39 and 40 while the lower end of said lever ispositioned to be engaged by the inner end of a horizontally slidable tappet rod 53a. Tappet rod 53a 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 of a bell crank lever 55 which is pivoted to a 1 hereinafter described.-

suitable bracket 56. The'remaining arm 51 .01 the bell crank lever is connected to the upper end of a link 53 the lower end of which is ad- .justably connected as at 59 to one end-of a cam operated lever 60. The cam operated lever 60 is mounted-to swing about a pivot 6| and-carries a roller 62 which rides thesurface of a reversing cam 53. Cam 63 is fixed to :rotate with a shaft 65 which is driven by gears 66, $1, 68. from a rack 59 carried byand movable with'the platen 5.

When the ram 13 has completed its-power stroke, or a predetermined portion thereof, as determined by the setting of the; cam 63,;the .lift portion 1!! of said cam engages the roller .62 (and lifts the .free end of thelink 150. The resulting upward movement of link 58 moves the bell-crank lever 55in a clockwise direction so that the arm 54 of the bell crank lever :acts against the .tappet rod 53a to move the latter to .the right againstthe lower end of lever 52. The upper end of lever 52 is thus swung to'the left and acts to shift the pivotal connection 4'! between the links 35 and 45 to the left .of the center line between the shaft 43 and the toggle pin 49 (see Fig.5). The toggle links39 and 40 then collapse to the position shown in Fig. 4 permitting the valve .28 to move downwardly from the power stroke position shown in Fig. l 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 28 from the position shown in Fig. l to the position shown in Figs. 4 and :5 maybe varied in relation to the powerstroke of the ram 13 by changing the angular setting of the cam 63 as The shifting of the valve member: 28 fromthe return stroke position shown in Figs. Land 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. i the lever 42 is first raised to shift the toggle arm 4| and the links 39 and 4! to the position shown in Fig. 5. With the parts in this new position lever 4-2 is thenswung downwardly to successively shift the arm 4! and the links 39 and 45 to the position shown in Fig. 6. During this last motion plunger 38 and valve 28 are moved upwardly since the two links 39 and lii become rigid in the position shown in Fig. 5 by reason of the fact that the shaped stops 45 and 4.6 prevent further counter-clockwise rotation of l nk '39 with reference to link 46. In connection with this resetting of the'toggle mechanism it will be .understood that the lever 52, tappet rod 530., bell crank 55, link 58 and cam operated lever 60 resume the position shown in Fig. l as soon as the cam lift ill passes beyond the roller 62.

The slow down valve provided in accordance with this invention comprisesa valve member 12 working in a valve casing 13 included in the fluid line 26. Valve member 12 is normally held in a fully open position by a spring 13a working against the valve stem 14. As long as this valve remains open during the power stroke of the ram 53, the exhaust of fluid from thepush back casing i8 via fluid line 25 is unobstructed and permits the ram 53 to descend at maximum speed. At a suitable instant prior to engagement of the work by the platen 5 or the tool carried thereby the valve T2 is shifted from the fully open position shown in Figs. 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 l8 through the valve casing 13 is throttled down so that the descending speed of the ram I3 and the platen 5 is sufil ciently reduced so that the platen -5 or .the tool carried thereby is brought in contact with :-the work while travelling 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 t-hroughthe agency of the control cam mechanism'generally indicated at 16. This mechanism includes a bell crank lever 11 pivoted to a bracket'iportion 18 of the valve casing 13. One arm -19 of lever 11 is fitted .in a vgroove'lll] 'provided in the'valve stein 14. Theotherarm 8| of lever '1'! is connected by a link 82 to the free end of a cam operated lever 83,-rthe-remaining end of the lastmentioned lever being pivoted as indicated at 84. Lever B3 'is provided with a stop 85 and with a pair of swinging links 81 the latter having their upper ends pivoted to opposite sides of the lever A roller 818 'iscar-ried between the lower ends of links 81 andisdisposed to ride the edge of cam 89 which is driven from the same shaft which drives the reversingrcam $3. During part of the power stroke. oftheram -the lever 23. links 81, roller 88 'and cam -89 are in the position shown in Fig. 1, the slow down valve l-2 being open. As the cam BH-is rotatediin the direction ind cated by the arrow) from thepositionshown .n Fig. l to the position shown in Fig. 2, the roller tadrops into the cam recess 9|, the links being prevented from swinging beyond the vert cal position: shown in Fig. 2 by engagement of said links with the stop 85. As the cam 89 continues to rotate from the position shown-in Fig. 2 o the position shown in Fig. 3 the .roller 88 rides on the lift portion-52 of-the cam and onto the curved cam surface 93, thus raising lever, stand link 32 and swinging the bell crank lever. 11 in a clockwise direction so that the slow down valve i is shifted from the fully open position shown in Figs. land 2 to thepartly closed position shown in 3. The particular instant, inrelation to the power stroke of the .ram 53, at which the slow down valve i 2 is shifted from the position shown in Fig. 2 to. the position shown in Fig. 3 may bevaried by changing the angular position of the cam 89 as hereinafter explained. The l ft portionlll of the reversing cam Std-s pro vided with-a laterallyextending arm .95 compare Figs. 1, 8, l0 and 11. When the lift portion 10 of cam 53 is rotated from the positionshownin Fig. 1 to and beyond the valvereversing position shown in Figs. 4 and 7 the arm 96 thereof engages a projection 91 of one of the links 8'! -(Figs."7 and 8) so that the links Bfl and the .roller88' are swung back to the position shown in Fig. lIthus perm tting lowering or resetting of the lever 33 to return the slowdown valve 12 to its normally fully open position. When valve 12 is butted against the leithandend of cylinder 13, as shown in Fig. l, the lever 83 is prevented from dropping below the position shown in this figure'by the link 82. I

In Figs. 8 and 9 I have shown what I new consider to be the preferred mechanical assembly of the component parts of the cam mechanism diagrammatically illustrated in Fig. 1. As here shown the central portion of shaft 55 is journalled in a bearing 89 provided in the wall Hill of a casing lfll containing the cams 63 .andfili. Shaft 65 is also partly journalled in a bearing lll2 provided in a shaft supporting portion m3 of a bracket [04 which is cast integral with or otherwise attached to casing Illi. The previously mentioned gears 65 and 51 are arranged between the. casing wall I81 and the bracket portion I03,

the gear 66 being keyed to shaft 65 in mesh with the gear 61 which is keyed to a shaft I05 which also carries the gear 68 and which is journalled in suitable bearings I06 and I01.

' Cam 63 is clamped in place between the shoulder 65a of shaft 65 and a clamping plate I09 which is jammed against a friction facing IIO secured to said cam. The clamping plate I09 is provided with a hub III which is slidably keyed to the shaft 65. The cam 89 is slidably fitted on the hub I I and is clamped against a friction facing H2 of the clamping plate I09 by means of a clamping nut H3 which is threaded onto the free end of hub III. A second clamping nut H4 is threaded on the right hand end of shaft 65 as viewed in Fig. 8 and acts against the free end of hub I I I to force the clamping plate I09 against the friction facing IIO of cam 63. A washer H6 is interposed between hub III and clamping nut H4 and is provided with a tongue II'I fitted in the hub groove I I8.

When it is desired to change the angular displacement of cam 63 this may be conveniently accomplished by loosening the clamping nut II4 sufficiently to permit cam 63 to be turned about shaft 65. When it is desired to change the angular displacement of the cam 89 this is accomplished by loosening the clamping nut II3 sufficiently to permit said cam to be turned about the supporting hub I I I. The clamping plate I09 may be graduated as indicated at H9 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 presses in 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 suitable 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.

What I claim is:

1. Cam mechanism comprising a cam shaft having an abutment thereon, a cam rotatably mounted on said shaft adjacent said abutment, a clamping plate slidably keyed to said shaft and adapted to be forced against the side of said cam remote from said abutment, a second cam rotatably mounted on a hub extension of said clamping plate and adapted to be clamped against the side of the clamping plate remote from the first mentioned cam member, a second clamping plate slidably keyed to said hub and adapted to be clamped against the side of the second cam member which is remote from the first mentioned clamping plate, a clamping nut having threaded engagement with said hub and adapted to be screwed into clamping engagement with said second clamping plate and a second clamping nut having threaded engagement with said shaft and adapted to be screwed against said hub to clamp said first mentioned cam in place between said shaft abutment and said first mentioned clamping plate.

2. Cam mechanism as set forth in claim 1 including a separately formed friction facing interposed between each cam and the adjacent side of the first mentioned clamping plate, each friction facing being non-rotatably secured to one of the opposing surfaces between which it is interposed.

3. Cam mechanism comprising a cam shaft, means for rotating said shaft, a cam mounted on said shaft to rotate therewith, a cam-operated lever having a portion thereof opposed to the periphery of said cam, a roller riding the periphery of said cam, swingable roller-carrying means securing said roller to said lever, means associated with said lever to limit swinging movement thereof toward the periphery of said cam, the contour of said cam and the relative arrangement of the cam, lever and roller carrying means being such that the roller carrying means is held in an inclined position relative to the lever when the roller is riding a predetermined portion of the cam but swings to a position normal to the lever when another portion of the cam which is of minimum radius is rotated into contact with the roller, a stop arranged to arrest further swinging movement of said roller carrying means after the latter has swung from its inclined to its normal position with reference to said lever, said cam being so contoured that, following movement of the roller carrying means to a position normal to said lever, portions of the cam 0f gradually increasing radius from the minimum to' the maximum are rotated into contact with the roller to effect outward movement of the roller carrying means and lever with reference to the axis of the cam shaft, the direction of rotation of the cam being such that the cam tends to maintain the roller carrying means against said stop when said roller carrying means is in a position normal to said lever and means functioning, at a predetermined instantsubsequent to the aforesaid outward movement of said lever, to swing said roller carrying means back to an inclined position with reference to said lever to permit the latter to move inwardly to its original position, said cam mechanism being further characterized in that the roller rides on and is supported by said cam in both positions of said roller carrying means.

4. Cam mechanism as set forth in claim 3 in which the said means for swinging the roller carrying means back to an inclined position with reference to said lever is secured to the cam shaft to rotate therewith.

' 5. Cam mechanism as set forth inclaim 3 in which the means for swinging the roller carrying means back to an inclined position with reference to said lever comprises a member secured to said cam shaft to rotate therewith, said member and said cam being adjustable about said shaft to various positions of angular displacement.

6. Cam mechanism as set forth in claim 3 in which the means for swinging the roller carrying means back to an inclined position with reference to said lever comprises a disk member secured to said cam shaft to rotat therewith, said disk member being provided with a lateral projection adapted, when moving through a predetermined portion of its circular path of travel, to engage and swing said roller carrying means to said inclined position.

7. Cam mechanism comprising a rotary cam shaft, means for rotating said shaft, a first cam mounted on said shaft to rotate therewith, a second cam mounted on said shaft to rotate therewith in side by side relation with the first cam, a first pivotally mounted lever having a portion thereof opposed to the periphery of the first cam, a second pivotally mounted lever having a portion thereof opposed to the periphery of the second cam, a roller riding the periphery of the first cam, swingable roller carrying means securing said roller to the first lever, means for limiting swinging movement of the first lever in the direction of the periphery of the first cam, said roller carrying means being held in an inclined position relative to the first lever when the roller is riding a predetermined portion of the first cam but being swingable to a position normal to said first lever when another portion of the first cam, which is of minimum radius, is rotated into contact with said roller, a stop arranged to arrest further swinging movement of said roller carrying means after the latter has swung to a position normal to the first lever, said first cam being contoured so that, following movement of said roller carrying means to a position normal to said first lever, portions of the cam of gradually increasing radius from the minimum to the maximum are rotated into contact with said roller to move the first lever outwardly with reference to the cam shaft, the direction of rotation of the cams being such that the first cam tends, by its engagement with said roller, to hold the roller carrying means against said stop when said roller carrying means is in a position normal to the first lever, a roller carried by the second lever and disposed in riding engagement with the periphery of the second cam and means carried by the second cam adapted to engage and swing said roller carrying means back to its inclined position with reference to the first lever at a predetermined instance subsequent to the aforesaid outward movement of the first lever with reference to said cam shaft, said cam mechanism being further characterized in that the first mentioned roller rides on and is supported by the first cam in both positions of said roller carrying means.

J OHN H. MAUDE.

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