US2304620A - Fluid operated slowdown mechanism for presses - Google Patents

Description

l Dec. s, 1942.

v. s. SHAW FLUID OPERATED SLOW DOWN MECHANISM FOR PRESSES Filed Jan. 5, 1940 IIE'.

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0 l a 6 a) 5 O l 0o m f ...ma .n.0 a 65 .l 5 M 4 610 9 a v INveuroR' V'ITwff ArronNeYs Patented Dec. 8, 1942 A,UNITED STATES PATENT AoFFlcrs y FLUID OPERATED/ SLOWDOWN MECHNISM FOR PRESSES Victor S. Shaw, Cardington, Ohio, assignor to The Hydraulic Development Corporation, Inc., Wilmington, Dell., a corporation of Delaware Application January 5,1940, Serial No. 312,566

- 9 Claims. (Cl. 60-52) The present invention relates to presses, and

vin particular to :duid operated presses, in which at the end of the press operation means are actuated for reversing the movement of the pressing platen. j

It is an object of Athe invention to provide a press of the above type, in which the return movement of the press yplaten may be slowed down when desired.

Another object oi' the invention is to provide a press having its press platen returned by uid in providing a fluid operated press of the char-4 acter set forth in the preceding paragraphs with controlling means for varying the time of the slow-down operation.

Still another object oi the invention consists.

in providing a fluid operated press of the type set forth above with a single control means which when moved into one position will cause the platen to start its return stroke slowly and.

then gradually to speed up, and, when moved into another position, willv cause the platen to move rapidly during the rst portion of its return stroke and then gradually to -slow down.

`These and other objects and advantages wil1 v appear more clearly from the following description in connection with the accompanying drawing in which: I

Figure 1 illustrates diagrammatically a fluid operated press in connection with a slow-down device according to the present invention;

Figure 2 shows, on a somewhat larger scale, a detail of the slow-down device.

In the drawing, I is a double acting press piston which is reciprocably mounted in the bore 2' of the main cylinder 3 and carries by means of the piston` rod B a press platen 5. The main cylinder 3 has two ports S and i which communicate with a conduit 8 and 9 respectively. The conduit 8 communicates with a conduit I0 leading to one side of the uid pump Il, while the conduit 9 communicates with a conduit l2 leading to the other side of the uid pump ll. Arranged between'the conduits 8 and 9 is a valve casing I3 subdivided into three chambers I, I5

and-|6 by means of partitions' l'l and\I8. The partitions Il and I8 have apertures I9 and 20 through which a double valve 2l extends and through which, according to the position of said valve, the chamber l5 may alternatively communicate with the chamber It or the chamber i6. The chamber I4 further communicates through a conduit 22 with a uid filled tank 23.

'I'he main iiuid pump II is preferably of the variable delivery type, and its discharge may be controlled either bythe provision of the reversing valve or by shifting the flow-control element of the pump directly. In 'the form shown in the drawing, the main pump II is provided with a servomotor IIa having a piston-and-cylinder assembly for moving the now-control element to and fro. .The servomotor ila is supplied with pressure fluid from an auxiliary pump (not shown), and its operation is controlled by means of the servomotor valve rod IIb. Thus by moving the servomotor valve rod IIb in or out, the servomotor Ila may be caused to shift the 'ow control ring of the main pump II in opposite directions and thus change the direction and vary the quantity of the pressure uid supplied The details of this' by the 'main pump II. servomotor control system forml no part of the present inv'ention and will be found disclosed in the U. S. Patent No. 1,861,116.

When the platen 5 is to perform a pressing stroke, the pressure uid is supplied from the main pump Il through conduits Il! and 8 into that portion of the bore 2 which is above the press piston I. The press platen 5 has connected therewith an arm 25 Withla collar v2S through which extends a push rod 2l.`- The collar 28 is adapted to engage a collar 2'8 adjustably mounted on the push rod 2l. The push rod 2 has a second collar 29, likewise adjustably mounted thereon which is adapted to engage a roller 3@ carried by a lever 3l. The lever 3i is shiftable about a pivot 32 and-has an arm 33 pivotally connected with a rod 3d which, in its turn, is

- The lever 3l is 'provided with a crank 63 whichv is`connected by the link Ml to one arm of a bell crank lever B5 shiftable about the stub shaft 66. The other arm of the bell crank 45 is connected by a link .dl with one arm of a bell crank lever 48 shiftably mounted upon the stub shaft 49. The other arm of the bell crank lever 48 is connected by a link 58 with the servomotor valve rocker arm I which is pivotally supported upon the oating link 52 mounted upon the housing of the servomotor. The servomotor valve rocker arm 5| is pivotally connected with the control valve rod I Ib. The crank arm 43 of the lever 3| is also connected with a tension spring 53, the other end of which is connected with a flxed point54. 5 HIFI Below and in axial alignment with the push rod 21 is a piston rod 55 carrying at its upper end an abutment 56, for instance a screw head, which is adjustable relative to the piston rod 55 by means of the threaded shaft 51 connected with the abutment 56 and engaging a corresponding thread in the piston rod. 'I'he lower end of' -the piston rod 55 carries a piston 58 reciprocably mounted in the bore 59 of the slow-down cylinder 60. The bore 59 of the slow-down cylinder 69 communicates through openings 6I and 62 with conduits 63 and 64 respectively. Leakage from the bore 59 is prevented by a packing 65 and gland 66 andby a gasket 61 in cooperation with the closure 68.

The conduit 63 leads to a port 69 of a fourway valve comprising a casing and a cock 1I having two channels 1| a and 1Ib. 'Ihe cock 1I is adapted to be rotated by 90 by means ofl a lever 12. The valve casing 1|l comprises a port 13 communicating through a conduit 14 with the conduit I0. A further port 15 in the valve casing 1|) communicates with a conduit 16 which leads to a chamber 11 of a choke valve 18 having a tapered bolt adjustably mounted therein. The chamber 11 also communicates with the lower port 62 of the bore 59 by means of the conduit 64. A further port 80 vin the four-way valve casing 10 communicates through a conduit 8|. with the conduit I2. I

The operation of the device is as follows:

Assuming that the pump II is in neutral position'and the remaining parts are in the position shown in Figure 1, the operator shifts the switch arm 39 so thatthe Acontacts 38 and 4| engage eachother. Current-.then flows from the main line 42 through contacts 4| and 38 and through the solenoid 36 to the main line 31, thereby energizing the solenoid36. The solenoid 36 attracts its armature 35 and shifts the lever 3I in clockwise direction which in its turn, by means of the lever system 44, 45, 41, 48, 56, 5| and lllnmoves the pump II into position for delivery of fluid into the conduits I0 and 8 through which the fluid enters the bore 2 of the main vcylinder 3. The liquid belowthe piston I escapes through the conduits 9 and I 2A and flows to the suction side of the pump II. 1

During the rstportion of the downward stroke of the piston the latter moves downward by gravity and liquid from the tank 23 flowing through conduit 22, aperture I9 and conduit 8 supplements the liquid delivered by the pump II to fill that portion of the bore 2 which is above the piston I. At the same time a portion of the iluid delivered by the pump flows from the conduit I0 through the conduit 14, the channel 1|a .and conduit 63 into that portion of the bore 59 which is above the piston 58 of the slow-down cylinder 60. 'I'he liquid above the piston 58 `moves the latter downward to its lower position so that the push rod 21, due to its gravity, can follow the downwardmovement of the platen arm 25 without interference by the abutment 56.

the conduit 64, the chamber 11, the conduit 16, the channel 1lb and the conduit 8| to the suction side of the pump II.

As soon as the platen 5 contacts the workpiece, uid pressure is built up in the conduit 8,

which pressure causes the valve-2| to move toward the right thereby closing the aperture I9 and releasing the aperture 20. 'Ihe iiuid in the conduit 64, choke valve chamber 11 and conduits 16, 8| and I2, which now communicates through the aperture 2|) with the fluid tank 23 cannot lift the piston 58 of the slow-down cylinder 60 against the iluid pressure built up by the pump I I since the iluid pressure of the latter is higher. Consequently, the piston 58 remains in the position into which it was moved by the fluid above the piston 58. l

When the platen 5 approaches the end of its .working stroke, it shifts the switch arm 39 in anti-clockwise direction, thereby disengaging the contacts 38 and 4I and de-energizing the solenoid 36. The armature 35 is then released and spring 53 shifts the lever arm 3| in anti-clockwise direction. This shifting movement of the lever 3| causes by means of the lever system 44 to 5| and I Ib, a rapid movement of the pump into position for full delivery of uid through conduits I2 and 9 into that portion of the bore 2 which is below the press piston I, thereby starting a rapid return stroke of the platen 5. At this time the pressure in the conduits I2 and 9 causes the valve 2| to move toward the left thereby closing the aperture 20 and releasing the aperture I9 in theA valve casing I3. Furthermore. at this time, a portion of the liquid delivered by the pump into the conduit I2 flows through' the conduit 8|, the

channel 1lb, the conduit 16, into the choke valve chamber 1 1. From there the liquid ows through the conduit 64 into the bore 59 of the slow-down cylinder 69 where it lifts the piston 58.

When the platen '5 during its return stroke has reached a predetermined position, the piston 59 has been lifted to such an extent that it engages the lower end of the push rod 21 and gradually lifts the same so that the collar 29 on the push rod 21 engages the roller 38 and shifts the lever 3| in. clockwise direction. 'I'he lever 3| then in its turn moves the servomotor valve rod IIb toward the right by means of the lever system 44 to 5I, thereby decreasing the pump stroke. In this way the press speed will be gradually slowed down and reaches its slowest speed when the piston 58 is in itsuppermost position. When the platen 5 has reached its uppermost position, the

collar 26 engages the collar 28 and lifts push rod 21 which, inits turn, by means of the collar 29, engages the roller 36 of the leve 3| and moves the latter in clockwise direction. This movement of the lever 3| shifts, by means of the lever system 44 to 5I, the pump I| into its initial position. .'I'he press is now ready for the next working stroke. Y

If it is desired to have the return stroke start slowly and gradually speed up, the four-way valve cock 1| is turned by 90 by shifting the lever 12 into the position indicated in dot-dash lines in Figure 1. The ports 13 and 15 then communicate through the channel 1lb while the ports 69 and 88 communicate with each other through the The fluid below the piston 58 escapes through 75 channel 1I a. When switch arm 39 is now shifted in clockwise direction so that contacts 38 and 4I engage each other, the solenoid 36 is energized. and as previously Idescribed, the pump I I'and the tank 23 deliver liquid into the cylinder bore 2 above the press piston I. At the same time, iiuid down plunger provided with iluid operable advancing and retracting means adapted to receive fluid from said pump to reciprocate said slowdown plunger, means operable by said slow-down plunger for restricting the ilow o! uid from said pump to said press plunger during a predetermined portion cf the return stroke of said press plunger, means for selectively varying the period of said flow restriction independently of the travel of said press plunger, and a four-way valve with four ports having twoports thereof respectively connected with said press plunger advancing and retracting means and the other two ports respectively connectedwith said slow-down plunger advancing and retracting means, said four-,way valve being adapted selectively to esto said main cylinder and associated with means to alternately effect a working stroke and a return stroke of 'said press plunger, slow-down means comprising an auxiliary cylinder and a -double-acting pslow-down piston reciprocable in 1s* 'last mentioned two conduits operable selectively tablish communication of each port with one oi' its two adjacent ports thereby controlling the fluid from said pump to said slow-down plunger advancing and retracting means so as to cause said press plunger either to start its return stroke slowly and then gradually to speed up or to move rapidly during the ilrst portion of its return stroke and then gradually to slow down.

4. In combination in a hydraulic system, a main cylinder with a double-acting main plunger therein, anauxiliary cylinder, a double-acting auxiliary plunger reciprocable in said auxiliary cylinder, a iluid source for supplying pressure iluid to said cylinders for actuating said plungers, control means operable by said auxiliary plunger for reducing the delivery of saidr fluid source to slow down the speed of travel of said main plunger, conduit means connected to said'iluid source and to each end of said main cylinder, a four-way valve controlling communication between opposite ends of said'main cylinder and the opposite ends of pressure fluid from said fluid source to one or thelother side of said auxiliary cylinder independently oi' the travel of said main plunger, and an adjustable throttle interposed between said four-way valve andone end of said auxiliary cylinder for varying the speed of movement of said auxiliary plunger in both directions.

5. In combination in a hydraulic press, a press plunger having associated therewith fluid operable? advancing and retracting means for reciprocating said press plunger, an auxiliary plunger associated with fluid operable advancing and retracting means for reciprocating said auxiliary plunger, a iluid source adapted to supply pressure iluid to said press plunger advancing and retracting means and to said auxiliary plungeradvancing and retracting means, a first conduit means connecting said fluid source with said press plunger advancing means, a second conduit means connecting said fluid source with said press plunger retracting means, means associated with said fluid source for directing pressure fluid alternately to said press plunger advancing and to said press plunger retracting means, a third conduit 'means and afourth conduit means respectively connected to said auxiliaryadvancing means and to said auxiliary retracting means, a four-way valve for controlling communication of to vary the slow-down period of said slow-down piston, said four-way valve being adapted, when moved into one position, to cause said press plunger to start its return stroke slowly and then gradually to speed up, and when moved into another position to cause said press plunger to move rapidly during the first portion of its re,-

\ turn stroke and then gradually to slow down.

` to alternately eileot a working stroke and a re- V,turn stroke of said platen, controlling means including a lever system for varying the delivery stroke of said pump, a fluid operable double-acting slow-down cylinder piston assembly adapted f to be actuated by fluid from said pump and to operate said lever system during a predetermined portion of the return stroke of said platen, adjusting means associated with said slow-down cylinder-piston-assembly and said lever system for varying the7 operative connection therebetween, and a valve controlling the supply oi fluid from said pump to vsaid slow-down cylinder and movable selectively into one position, to cause the platen to start its return stroke slowly and then gradually to speed up, or into another position to cau'se said platen to move rapidly during the first portion of its return stroke and then gradually to slow down,land a throttle hydraulically connected with and interposed between said valveand said'slow-down cylinderand-piston assembly and adapted-tovary the time period of the slow-down or speedup operation of said slow-down cylinder-and-piston assembly.

8, In combination in a press,'a movable platen, a double-acting cylinder-and-piston assembly operatively connected with said platen for reciprocating the same, a reversible variable delivery pump for supplying fluid to said assembly to alternately eilecta working stroke and a return stroke oi said platen, spring means constantly urging said pump into full delivery position for the return stroke of the platen, a reciprocable member adapted to counteract said spring means,

slow-down means comprising a slow-down plunger having associated therewith advancing and retracting means operable by fluid from said said ilrst and second conduit means with said third and fourth conduit means, and an Ladjustable throttle .valve Ifor varying the flow of fluid between said auxiliary plunger retracting means and said four-way valve' to vary the travelling speed of said auxiliary plunger in one direction.

6. In combination in a press, double-acting press plunger reciprocably mounted in a mainl cylinder, a fluid pump adapted to supply fluid pump, said plunger being adapted to move said reciprocable member, against the influence of said spring means during a' predetermined variable portion of the return 'stroke of said platen to restrict the delivery stroke of said pump, adjustingmeans associated with said slow-down plunger for changing thelength thereof to determinelthe minimum delivery stroke of the pump during the return stroke of the platen. and a valve adapted to control the supply of iiuld to said slow-down plunger so as selectively to cause the .platen to start its return stroke slowly and then gradually to speed up, or to cause said platen to move rapidly during the i'lrst portion of its return stroke and then gradually to slow down.

9. In combination in a press, a press plunger having associated. therewith fluid operable advancing and retraeting means, a variable delivery pump for supplying fluid to said advancing and retracting means for actuating said plunger,

means associated with said pump to alternately effect a working stroke and a return stroke of said platen, controlling means including a lever system for varying the-delivery stroke of said pump, means operable to shift said lever system in one direction, spring means urging said lever system in another direction, a push rod adapted to engage and disengage said lever system to control the same, slow-down means including a 'double-acting fiuid'operable cylinder-piston sys tem adapted to be hydraulically connected with said pump and to operate said push rod independently of the travel of said press plunger for y

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