US2143112A - Press with compound ram - Google Patents

Description

Jan. 10, 1939. H. F. M MILLIN PRESS WITH COMPOUND RAM Filed A ril 22, 1936 2 Sheets-Sheet 1 ow/1R1) F. Mae. MILL IN,

G m/ r Jan. 10 1939.

Filed April 2 2, 1956 2 Sheets-Sheet 2 FICT. 3.

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2 Claims.

This invention relates to presses, and in particular, to a hydraulic press having a compound main ram.

One object of this invention is to provide a hydraulic press with a compound main ram, one

portion of which is adapted to impart a relatively low pressing effect to the platen and the other portion a relatively high pressing effect thereto.

Another object is to provide such a press with a compound main ram, wherein one portion is adapted to impart a relatively low pressing effect to the platen and the other portion a relatively high pressing effect thereto, the two portions being adapted to be utilized either separately or simultaneously.

Another object is to provide a hydraulic press having a compound main ram with a. plurality of portions to which the operating fluid may be selectively admitted, thereby providing a pair of piston head areas adapted to give different speeds and pressing force to the platen, one area being capable of imparting a relatively high speed to the platen with a relatively low pressing force, and the other area being capable of imparting a slower speed to the platen with a higher pressing force.

Another object is to provide a hydraulic press circuit having a press with a compound main ram and a valve arranged to deliver fluid to one portion of the ram during one part of the stroke, and to be shifted to deliver fluid to another portion of the ram during another part of the stroke, this valve being preferably shifted by the motion of the platen Another object is to provide a hydraulic press circuit having a press with a compound main ram, and a distributing valve therefor which delivers fluid to the inner area of the rain during the initial part of the pressing stroke, this valve being shifted, as by the platen, to deliver the pressure fluid not only to the inner area but also to an -additional outer area so as to complete the pressing operation, with the exertion of a higher pressing force. In this manner the actual working stroke is carried out in two stages, the first stage being accomplished at a relatively higher speed and medium pressure, and the second stage at a slower speed but at full pressure.

In the drawings:

Figure 1 is an elevation, partly in section, of a hydraulic press with a compound main ram and an actuating circuit, according to this invention.

Figure 2 is a central Vertical section through the distributing valve used in connection with the circuit of Figure 1.

Figure 3 is a view, partly in section, showing the arrangement for actuating the valve rod by means of a platen arm.

Figure 4 is a view similar to a portion of Figure 1, but modified slightly to provide a by-pass line and by-pass valve around the distributing valve. General arrangement Referring to the drawings in detail, Figure 1 shows a press having side frame members ID, a bed II and a top member l2, these being secured to the side members or strain rods in by the nuts i3. The bed I I is provided with an upper surface l4, upon which suitable dies or holders for workpieces may be placed. The upper frame member i 2 is adapted to serve as the cylinder for the main ram, and for this purpose it is provided with a cylinder bore l5, within which is mounted a tubular main ram l6 attached at its lower end to a platen l1, having guide plates l8 adapted to engage the frame side members ID for guidance during the motion of the platen downwardly toward the bed I I. The platen I1 is provided with lateral extensions Hi, to which are attached the threaded upper ends of push-back plungers 20, as by the nuts 2|. The push-back plungers operate in push-back cylinders 22 having cylinder bores 23 with glands 24 .and packings 25 surrounding the plungers 20 toprevent leakage. The hydraulic connections of these push-back cylinders 22 will be subsequently described.

The'main ram I 6 is provided with a hollow bore 26 adapted to receive a tubular member 21, having a fluid-tight engagement therewith, as by the piston rings 28 at the bottom thereof. The tubular member 21 is mounted in a bore 29 at the upper end of the frame top member l2, and is provided with a surge valve 30 opening into a surge tank 3| adapted to contain the operating fluid for the pump. Above the upper end of the cylinder bore I5 is an enlarged portion 32, forming an annular chamber 33 surrounding the tubular portion 21.

Mounted in bores 34 above these annular chambers 33 are surge valves 35, similar to the surge valve 30 previously mentioned. The surge valves 3|) and 35 may be of any suitable and conventional type, and their details form no part of the present invention. The particular surge valve shown is disclosed in detail in the patent to Walter Ernst, No. 1,892,568, issued December 2'7, 1932. The surge valves 30 and 35operate, as w ll subsequently appear, to permit the main ram l6 to descend under the influence of gravity and to draw fluid freely into the main cylinder bore [5 and the inner bore 36, through the surge valves 3!] and 35, but when the power is applied to force pressure fluid into this space the surge valves 30 and 35 are automatically closed, causing the remainder of the stroke to take place under pressure. This arrangement serves to permit a more rapid descent of the platen than would be possible if the platen were actuated entirely by fluid pressure. Upon the return stroke of the press the surge valves 30 and 35 open to permitfluid to be discharged into the surge tank 3! in a reverse manner. The tubular member 27 is provided with an inner bore 36, forming a conduit for conducting fiuid from the surge valve 30 to the inner bore 26 of the main ram l6, and vice versa. The space between the main ram l6 and the main cylinder bore l 5 is closed by a packing 31, adapted to be compressed by a gland 38 therebeneath.

Mounted on one side of the press top member I2 is a distributing valve 48, which serves in cooperation with the pump 39 as a shift-over valve to direct fluid initially to the inner portion of the main ram l6, and finally to the outer portion as well. The main ram i6 is provided with an outer annular piston portion ll and an inner end wall 42, which receive the thrust of the pressure fluid delivered by the distributing valve 4E]. The details of the distributing valve 30 will be subsequently described.

Hydraulic circuit The pump 39 is preferably of the reversible variable delivery type, and has a control hand lever 53 arranged to operate the control valve assembly 44 for the servo-motor d5 of the pump 39. For this purpose the control valve assembly 44 is connected by the lines Ma and Mb to the servo-motor 45, and by the line Mo to the forward delivery or pressing side of the pump'irlt. The servo-motor 45 contains a piston (not shown) adapted to move the shift-ring of the pump 39 to vary and reversethe delivery thereof. luid is supplied to the control valve through the lines 46 and 41 leading to the pressure and suction sides, respectively, of the low pressure pump it, the line 46 being likewise connected to the line 6| leading to the surge tank 3!. A pressure relief valve 58 by-passes the discharge of the pump 39 into the lines 4'! and iii when. the valve 54 closes off the line 48. The servo-motor d5 is also operated automatically by fluid reaching it by the line 4511 from the push-back side of the pump 39. The details of the servo-motor form no part of the present invention, and aredisclpsed in the patent to Walter Ernst, No. 1,861,116, issued May 31, 1932.

The pump 39 on its forward delivery side is connected by the line 64 to a make-up valve 59. This valve 49 is likewise of a conventional type, whose details form no part of the present invention, and contains chambers 50, El and 52 interconnected with one another by bores 53 and 5 2', within which reciprocates the valve member 55 having heads 55 and a fluted body portion 5?. The'purpose or" the make-up valve 59 is to provide for the intake of any necessary amount of fluid upon one side of the press required over that discharged from the other side of the press. It supplies fluid to make up for any difference in volume between the various cylinders, such as between the main cylinder and the push-back cylinders 22. I

The right-hand end chamber of h make up valve 49 is connected by the line 59 to the port 60, opening into the bore 36 of the tubular member 21 and continuing beyond this to the distributing valve 40. The middle chamber 5| is connected by the line 6| to the surge tank 3|. The left-hand end chamber 52 is connected by the line 62 to the push-back line 63, leading from the push-back connection 64 of the pump 39 to the push-back cylinders 22. Beyond the lefthand push-back cylinder 22 the line 63 continues in the line 65, leading in triple branch lines 66, 61 and 68 to the actuating chambers of the surge valves 3G and 35. The line 65 is also provided with branches 69 and 10, leading to the distributing valve 40. From the latter the remaining line H leads to the annular chamber 33 above the main cylinder bore 15. The distributing valve 40 is provided with a valve rod 12, the lower end of which is threaded, as at 13, (Figure 3) to support a nut 14 upon which rests a coil spring 15, surmounted by a tubular cap 16 having a bore 11 through which the valve rod 12 passes. The platen I! is provided with a valve-actuating arm 78 having a bore 79, through which the valve rod '12 likewise passes.

From Figures 1 and 3 it will be seen that when the platen H and the valve-actuating arm 18 descend the latter will eventually engage the tubular cap 76, compressing the spring 75 and forcing the valve rod l2 downwardly to shift the valve member in the distributing valve 40. The position of the tubular cap 76 relatively to the platen arm it? may be adjusted by rotating the nut M so as to change the position at which the platen arm 78 engages the cap 16.

Distributing valve The distributing valve 48 is provided with a casing 80 having a valve bore 8!, with upper and lower annular chambers 82 and 83 leading to ports 84 and 85, respectively. The port 84 is connected to the line 59. The port 85, which for convenience of showing is illustrated as diametrically opposite the port 84 instead of ninety degrees away from it, as in Figure 1, is connected to the line H. The lower and upper portions of the bore 8i are provided with ports 86 and 81, which communicate with the branch lines 69 and Ill, respectively, connected to the push-back line 65. Reciprocable within the valve bore BI is a valve member 90 having spaced heads 9i and 92 thereon. The valve member 90 passes through a washer 93, a packing 94 and a gland 95, arranged to compress the packing 94 by tightening the set screws 96,

A spacing element 9'! is arranged in the lower part of the bore 8|, whereas a tubular element 98 at the upper end of the bore 81 serves to receive the enlargement 99 above the valve head 9!. The upper end of the valve member 90 is threaded, as at I00, and is provided with a nut Hll operating against a washer N32 to compress a coil spring H13, the opposite end of which is anchored against the annular element I04 mounted on the gland at the upper end of the distributing valve 40. The gland M15 is similar in construction and operation to the lower gland 95,

and is provided with a packing MIG adapted to be I vary the tension of the spring I93 by adjusting the nut IOI.

Operation The press and circuit shown in Figure 1 may be operated in two different ways, depending upon the nature of the work and the desire of the operator. If it is desired to use only the inner ram of the press, such as for deep drawing work where a maximum ram speed is essential on account of the long stroke under pressure, the cap 16 is lowered by turning the nut 14 upon the valve rod 12 so that it will not be engaged by the platen arm 18 during the downward descent of the platen l1. When'the pump 39 is started, therefore, the fluid passes through the pressing connection 64 into the end chamber 50 of the make-up valve 49, and shifts the valve into the position shown in Figure 1. The pressure fluid continues upwardly through the line 59 and the port 60, into the bore 36 within the fixed tubular member 21, whence it enters the hollow bore 26 within the main ram IS. The latter has a small diameter end wall 42 and, assisted by its weight, descends at a relatively high speed, due to the comparatively small volume of the bore 26, which is required to be filled by the fluid.

Meanwhile, the surge valves 30 and 35 have opened as a result of the suction produced by the descent of the main ram l6, permitting fluid to be drawn into the bores 36 and 33, respectively, and thence into the hollow bore 26 of the main ram l6, thereby enabling the main ram l6 to descend more rapidly than would otherwise occur With the action of the pump 39 alone. When the platen engages the work-piece and encounters resistance, the building up of pressure within the inner bore 36 causes the surge valve 36 to close, thereby cutting oif communication with the surge tank 3|. The pressure within the bore 36 continues to act against the end wall 52 of the hollow bore 26 within the main ram l6 until this pressure exceeds the pressure setting of the servo-motor in the servo-cylinder 45, whereupon this servo-motor will operate the shift-ring of the pump and shift it towardits neutral position, thus cutting down the flow of the pump 39.

Meanwhile, the fluid discharged from the pushback cylinders 22, by reason of the entry of the push-back plungers 29, passes along the line 63 to the push-back connection 64 of the pump 39.

Any excess fluid required by the pump 39 for and the pressing connection 64 becomes the suction connection. Accordingly, the pump 39--delivers pressure fluid to the push-back cylinders 22 by way of the push-back line 63, causing them to move the push-back plungers 20 and the",

platen ll upwardly. Pressure fluid passes along the branch line 62 and acts against the valve head 56 in the end chamber 52, shifting the valve to the opposite position from that shown in Figure 1. In the position thus attained by the valve member 55 of the make-up valve 49, fluid passes between the pressing connection 64, which is now -rod 12. buting valve 49 then shifts the valve member 90 the suction connection, and the surge tank 3| by way of the line 6|, the middle chamber 5| of the make-up valve 49, the fluted portions 51 of the valve member 55, the end chamber 50 and the line 64. l

The fluid displaced by the upward motion of the main ram l6 passes from the bore 36 of the tubular member 27, through the port 60 and along the line 59 to the right-hand end chamber 50 of the make-up valve 49. If the quantity of this fluid is in excess of that required by the pump 43, the excess fluid passes into the middle chamber 5| and up the line 6|, into the surge tank 3|. The platen continues its upward motion until its motion is halted by the stopping of the pump 39, or by the automatic action of the servo-motor within the servo-cylinder in shifting the shiftring of the pump to neutral position.

If now it is desired to use the entire ram area and employ the maximum pressure of the press, the outer annular portion 4| of the main ram 6| must be used in addition to the end wall 42. This employment of the entire area of the ram l6 sacrifices a certain amount of speed, but produces a greater pressing power, such as is desirable for short stroke work, for example, coining and embossing. For this kind of operation the cap 16 is moved upwardly along the valve rod 12 by turning the nut 14 until it is engaged at the proper point by the platen arm 18. The pump 39 is then started and the pressure fluid passing through the line 59 and the. port 60 enters and fills the inner bores 26 and 36, assisted by the surge valve 30 as before. The main ram l6 and the platen I move downwardly, assisted by their own weight, in the manner previously described, the fluid being similarly displaced from the pushback cylinders 22.

When the platen n is moved downwardly to such an extent that the platen arm 18 engages the cap 16, compresses the spring 15 therein and shifts the valve rod I2 and the valve member 90 of the distributing valve 40, the latter shifts so that the heads 9| and 92 (Figure 2) move downwardly. This action opens communication between the valve chambers 82 and 83 and permits the pressure fluid to continue beyond the port 60, along the line 59 to the distributing valve 40. This fluid passes through the port 84, the valve chamber 82, the valve chamber 83, the port 85 (Figure 2) and the line1l into the annular chamber 33, where it acts upon the annular outer piston portion 4| of the main ram l6. The

pressure upon the outer piston portion 4|, addedto that upon the inner end wall 42, increases the pressing efiort exerted upon the platen I1 and further compresses the work-piece. This compression continues until the critical pressure is reached, at which the servo-motor within the servo-cylinder 45 of the pump 39 becomes operative to shift the pump to its neutral position.

When the pump is reversed the pressure fluid flows, as before, through the line 63 into the push-back cylinders 22, raising the platen l1 and the main ram l6 by the action of the push-back plungers 20. This action causes the platen arm 18 to rise and release the cap 16 and the valve The coil spring |03 within the distriand its heads 9| and 92 upwardly into the normally closed position thereof. This action, however, is counteracted by the flow of fluid along the line 65, from the line 63 into the branch lines 69 and 76, where the pressure from the push-back line 63 acts upon the unequal areas on the opposite sides of the valve member heads 9! and 92, thereby overcoming the upward urge of the spring 103 and holding the valve member in its downward or open position.

This keeping of the distributing valve 40 open permits the fluid displaced from the annular chamber 33 to escape along the line II, through the distributing valve 40 to the line 59, which is now the suction line of the pump 39. The surge valves 30 and 35 also open upon the release of pressure in their respective chambers, thereby permitting a portion of the fluid to escape directly into the surge tank 3|.

In the second mode of operation of the press, employing both portions 42 and 4| of the main ram IS, the surge valves 30 and 35 operate to permit the entrance of fluid from the surge tank 3| during the early portion of the descent of the main ram IS, in the manner previously described under the first mode of operation, using the central portion 42 of the main ram l6 alone. In the second mode of operation the working stroke will be thus carried out in two stages. The first stage takes place at a relatively higher speed, but applies a medium pressure, and the second stage occurs at a slower speed, but applies a higher pressure. Thisarrangement not only provides a press which is capable of doing the work of two different kinds of presses most economically, but also increases the speed of action of a high pressure press.

It will be apparent that an additional manual valve H I (Figure 4) may be placed in the bypass line H2 interconnecting the lines H and 53 so as to by-pass the flow oi the pump 39 around the distributing valve 40 and permit the outer and inner portions of the main ram Hi to be used from the start of the downward motion thereof, instead of waiting for the distributing valve 40 t'c; be operated by the action of the platen arm It will also be apparent that the present invention is decidedly superior to and different from the ordinary arrangement of a main ram provided with booster rams for rapidly traversing the main ram to the work. In order to perform the traverse quickly, these boosters must necessarily be small and consequently incapable oi doing any effective work. In contrast to in the present invention the main ram itself is divided into two major portions, each great enough in area to do useful work, and both completely equipped with surge valve systems for both prefllling and exhausting their respective cylinder chambers during the rapid traverse and rapid return movements. It will be understood, moreover, that in place of the gravity descent or rapid traverse of the platen, booster rams may also be provided in addition to the compound main ram as described above.

It will be understood that I desire to comprehend within this invention such modifications as come within the scope of the claims and the invention.

Having thus fully described my invention, what I claim as new and desire to secure by Letters Patent, is:

1. In combination in a hydraulic press, a main cylinder, a partition member therein dividing said main cylinder into outer and inner chambers, a main plunger in said main cylinder having outer and inner portions disposed respectively in said outer and inner chambers and forming outer and inner piston areas therein, a platen connected to said main plunger, a surge tank immediately adjacent said cylinder with a port opening into said outer chamber and another port opening into said inner chamber, a surge valve in each port adapted automatically to open to admit fluid from said surge tank into each of said chambers in response to the idle advance of said main plunger whereby to prefill both of said chambers automatically during said idle advance, means for returning said main plunger to its retracted position, means responsive to the operation of said plunger-returning means during the return stroke of said main plunger for forcibly opening both of said surge valves to release fluid from both of said chambers through said ports directly back into said surge tank, and means for d1- recting pressure fluid selectively to said inner and outer chambers of said main cylinder.

2. In combination in a hydraulic press, a main cylinder, a partition member therein dividing said main cylinder into outer and inner chambers, a main plunger in said main cylinder having outer and inner portions disposed respectively in said outer and inner chambers and forming outer and inner piston areas therein, a platen connected to said main plunger, a surge tank immediately adjacent said cylinder with a plurality of ports disposed on diametrically opposite sides of said partition member opening into said outer chamber and another port opening into said inner chamber, a surge valve in each port adapted automatically to open to admit fluid from said surge tank into each of said chambers in response to the idle advance of said main plunger whereby to prefill both of said chambers automatically during said idle advance, means for returning said main plunger to its retracted position, means responsive to the operation or said plunger-returning means during the return stroke of said main plunger for forcibly opening said surge valves to release fluid from both of said chambers through said ports directly back into said surge tank, and means for directing pressure fluid selectively to said inner and outer chambers of said main cylinder.

HOWARD F. MACMILLIN.

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