US2809543A

US2809543A - Compensating system for presses

Info

Publication number: US2809543A
Application number: US347329A
Authority: US
Inventors: Zeitlin Alexander
Original assignee: Baldwin Lima Hamilton Corp
Current assignee: Baldwin Lima Hamilton Corp
Priority date: 1953-04-07
Filing date: 1953-04-07
Publication date: 1957-10-15
Anticipated expiration: 1974-10-15
Also published as: ES214592A2

Description

Oct. 15, 1957 A. zElTLlN 2,809,543

l COMPENSATING SYSTEM FOR PRESSES Filed April 7. 1953 4 sheets-shet 1 l it IFI1 I l 1 ll 1 l T g n IHIL 35 30/ U 52 M 35 f A 7u, 33

E r-- I) i 34/ 3f ra ,swf/mamme@ Oct. 15, 1957 A. zElTLlN COMPENSATING SYSTEM FOR PRESSES Filed April 7, 195s 4 Sheets-Shea?l 2 B) F BD 33 22 M M M 2 2 .w M 2 42 2 M .Ik Vl In Cf fm A 2 C2 E2 @f w w AC 33 x) 22 fr Oct. 15; 1957 A. zElTLlN 2,809,543

COMPENSATING SYSTEM FOR PRESSES Oct. 15, 1957 A. zElTLlN 2,809,543

COMPENSATING SYSTEM FOR PRESSES Filed April 7, 1953 4 Sheets-Sheet 4 FIGA /25 FIG.5

United States Pub CNIPENSATING SYSTElNl FR PRESSES Application April 7, 1953, Serial No. 347,329

3 Claims. (Cl. 7S42) This invention relates to presses and the like in which a plurality of members are relatively movable towards each other to develop high pressures therebetween. The invention is particularly adapted for die forging presses having a moving platen and a rxed platen, in which a workpiece is shaped by the pressure developed between the dies carried by the platens. In such presses eccentric loading conditions are frequently encountered and, because of the high pressures developed between the platens, correspondingly high eccentric forces are developed which tend to tilt the movable platen and this may cause serious damage to the major components of the press, particularly to the columns or tie-rods which would be subjected to severe bending stresses.

In the copending application of Heinrich B. Albers, Serial No. 337,375, for lCompensating System for Presses, tiled February 17, 1953, there is disclosed an improved means for automatically counteracting or compensating for the stresses developed by eccentric loading of a press and the like of the type described above. Furthermore, said copending application discloses vhow a plurality of such compensating means may be employed to counteract eccentric stresses about a plurality of axes. The employment of a plurality of compensating means was attended by a cor-responding multiplication of parts and complexity of structure.

lt is therefore one of the principal objects of this invention to provide means for counteracting the development of eccentric stresses about a plurality of axes by the employment of a Simplified structure utilizing fewer parts and smaller volume than was heretofore possible.

Further objects and advantages of this invention will become apparent in the following detailed description thereof.

ln the accompanying drawings,

Fig. 1 is a view partly diagrammatic, partly sectioned vertically, showing the compensator elements applied to a closed die forging press of which only certain parts such as the platens `and the dies supported thereby are shown, the compensator pistons being in their upper positions.

Fig. 2 is a diagrammatic plan View of certain parts of the assembly according to Fig. l, showing the arrangement of a plurality of compensating units cooperating with the press platens .at a plurality of spaced posin'ons.

Fig. 3 -is a diagrammatic plan view similar to Fig. 2 but showing a modified system of compensating cylinders.

Fig. 4 is a rvertical section through the compensating unit of the Fig. 3 form of the invention.

Fig. 5 is a section taken substantially along the line 5 5 of Fig. 4.

Referring .to"Pig. l,`the invention is shown applied to a die forging press having a fixed platen and a moving platen 11 which is adapted to be moved toward the iixed platen 'by means of rams 12 actuated by iluid pressure from a source indicated diagrammatically. The upper platen carries an upper die 14 which moves toward the lower die 1,5 on the -xed platen, the workpiece 16 to be forged 4being supported on the lower die. The upper tent O 2,809,543 Patented Oct. 15, 1957 ICC platen 11 moves normally parallel to the fixed platen 10 by reason of the construction ,of the press which is provided with suitable guide members (not shown), but when the upper die engages the workpiece, particularly when the die or the workpiece is of irregular shape, the upper platen may be tilted out of parallelism with the lower platen. As stated in the introduction hereto, such tilting movement due to eccentric loading conditions develops large stresses in certain of the ,major components of the press, and especially in the columns or tie-rods which are subjected to severe bending stresses.

In order to prevent such large eccentric loading stresses from developing in the press, there is provided a compensating mechanism, one form of which is disclosed in Figs. l and 2. This mechanism comprises a plurality (here shown, for example, as six) of inclination responsive elements indicated generally at A, B, C, D, E, 'F (Fig. 2) and a single pressure element indicated generally at G and normally mounted on the foundation vadjacent the press. The inclination responsive elements are spaced so that regardless of the axis about which inclination may occur in practice, at least one element will be found on that side of said axis where the upper platen moves more rapidly toward the lower platen.

As shown in the drawings, each inclination responsive element comprises a cylinder 20A-F, and each cylinder accommodates a piston or ram 21A-F which is supported on a body of liquid 22 supplied through a pipe 23A-F from duid 24 contained within a cylinder 2SA-F on a iixed cross-head 3S. The fluid within cylinders 25A-F is controlled by pistons or rams 26A-F which are tixed to a movable cross-head 30. Thus, if as shown in Fig. 2, six inclination responsive elements A-F are employed there will be six pistons 26 fixed to the upper surface of, and movable with, the cross-head 30.

The movable cross-head 30 which supports the plurality of pistons 26 on its upper surface carries a single piston 32 on its lower surface, the piston 32 operating Within a fnxed cylinder 33. The piston 32 is supported by iluid 34 supplied from a primary source of uid pressure such as an accumulator (not shown) through a pipe 36. The xed cylinder 33 is shown integral with base 31 (Fig. ,1) connected to the iixed cross-head 38 by tie-rods 35. The size of piston 32 will depend upon the accumulator pressure which is normally relatively high. When no load is applied to the upper surfaces of pistons 21, a low-pressure is maintained in lines 23 from a source of pressure (not shown) through check Valves 37A-F which are adapted to open when the pressure in the respective line 23 falls below a predetermined value. Thus the accumulator pressure may be on the order of 4000 p. s. i. whereas the pressure in cylinders 20A-F when no loadis applied to the upper surfaces of pistons 21A-F maybe on the order of p. s. i. Stroke limits are provided to limit the upward movement of movable cross-head 30 and of pistons 21. In case of losses due to leakage, lines 23 are automatically replenished with fluid through valves 37 when the latter open upon a drop in minimum pressure.

Examining the structure as described above, it will be seen that the movable crosshead 30 is normally supported on the accumulator fluid, and that each of the pistons 21 cooperates with the cross-head 30 through its own separate hydraulic system. Further, it should be noted that the movable cross-head 30 represents a single pressure resisting means which is operatively and effectively connected to the inclination responsive elements A-F by intermediate means including the pistons 26, cylinders 25, fixed cross-head lor support 38, and pipes 23. It will also be apparent that the fluid pressure systems between the respective pistons 21 and the movable cross-head 30 are separate from the main hydraulic pressure system which operates on rams 12 to move the movable platen toward the fixed platen.

Bearing the foregoing facts in mind, the operation of the device as a compensating mechanism to counteract eccentric loading of the press will now be described. A

plurality of Contact members or stops 49 carried bythe upper platen cooperate with the respective pistons 21A-F. Suitable adjusting means (not shown) may be provided for these stops so that preferably they will just engage the respective pistons when the upper die 14 is about to engage the workpiece 16, or when it is substantially in engagement with the workpiece, that is, when substantial forces are developed. In other words, the pistons 21 are preferably disconnected operatively from the upper platen until the latter has substantially completed the idle part of its stroke. Thereafter, further downward movement of the platen will cause the stops 49 to press against all pistons 21 with equal pressure if there is no eccentricity along any transverse axis, and the pistons 26 will all be forced downwardly to equal degree to force piston 32 downwardly and discharge fluid into the accumulator, the main rams 12 being large enough to overcome the additional resistance. Thus, during concentricy forging, each of the pistons 26 applies equal force to thepiston 32. Y Y

Assume now that as the upper die engages the workpiece, eccentric loading of the upper plate develops, for example, around axis Y-Y in Fig. 2, so that the right hand side moves downwardly more rapidly than the lefthand side. The tilting of the platen is thus in a clockwise direction in the drawing, and greater pressure will be exerted on the pistons 21 of elements B, D, F than on pistons 21 of elements A, C, E. The pressure in

lines

23B, 23D, 23F will rise and

pistons

26B, 26D, 26F will press against piston 32 with a greater increment of force than

pistons

26A, 26C, 26E. The reaction pressures on

pistons

21B, 23D, 21F will be greater than the reaction pressures on

pistons

2A, 21C, 21E. In other words, there will be a differential force between sets of pistons 21 on opposite sides of axis Y-Y which will create a moment acting on the upper platen in a counterclockwise direction and counteracting the tilting motion, so that the upper platen will tend to turn back to and maintain its straight position parallel to the lower platen. Similarly, any tilting movement of the upper platen about any other axis will Ycause one or more pistons 21 to move downwardly faster than the other pistons 21, and the reaction pressures on the respective piston 21 will bring into play a corresponding correcting moment in a direction opposite to the original tilting movement of the upper platen.

As many inclination responsive pistons 21 may be employed as desired so that regardless of any possible axis of tilt of the upper platen, certain of the pistons 2 and their corresponding pistons 26 will be subjected to greater increment of pressure than the other pistons 2l, so that the reaction pressure will yield a correcting tilt to the upper platen. Y

As hereinbefore described, it will be apparent that when the upper platen tilts because of eccentric loading,

. greater pressures are developed on certain of the pistons 21 than on the others. Thus, if the upper platen tends to tilt in a clockwise direction around axis Y-Y, pistons 21B, ZID, ZF will move faster than

pistons

21A, 21C, 21E to place greater pressure on

pistons

26B, 26D, 26F, than on

pistons

26A, 26C, 26E. This will have a tend ency to tilt the movable crosshead 30. Such tilting does not result too seriously when the crosshead is of limited size and guided by means such as the tie-rods, as in Fig. l, but incertain installations it may be desirable to minimize the tendency of the movable cross-head to tilt. One means for accomplishing this result is disclosed in Fig. 3 wherein each cylinder 25A-F is operatively connected by a passage H3A-F to a similar cylinder IZSA-F within which operates a piston 126AeF, so that the pressure in each line 23 is equally distributed to the two cylinders 2S and 125 and pistons 26 and T126. Each counterbalancing cylinder i is preferably positioned in substantially diametrically opposite relationship to the respective cylinder 25, so that the pressures delivered by each piston 21 to its respective pair of

pistons

26 and 126 will be applied to the movable cross-head in balanced relationship. In this manner, any tendency of the cross-head 30 to tilt will be avoided.

Having described my invention, what I claim and de sire to secure by Letters Patent is:

l. In a hydraulic press, a fixed platen, a platen movable along a predetermined axis through an approach range and a working range, one of said platens being adapted to support a work-piece thereon, a plurality of pairs of duid operated compensating cylinder and piston units mounted on one of said platens and responsive to tilt of said movable platen, each of said units having a stroke substantially equal to the length of said working range, contact means on the other platenspaced from said compensating units at the start of a platen stroke so as to engage said units at a predetermined position of the movable platen substantially only within said working range, a series of intermediate lluid operated cylinders, a series of pistons coacting with said intermediate cylinders, a xed frame carrying one of said series, a single cross-head movable on said frame and carrying the other of said series, a plurality of iiuid connections, each of said tiuid connections joining one of said compensating cylinders to one of said intermediate cylinders, and actuating means connected to said single cross-head to generate pressures in said intermediate cylinders and compensatingcylinders for opposing tilt of said movable platen.

2. In a hydraulic press, a xed platen, a platen movable along a predetermined axis through an approach range and a working range, one of said platens being adaptedk to support a work-piece thereon, a plurality of pairs of fluid operated compensating cylinder and piston units mounted on one Vof Said platens and responsive to tilt of said movable platen, each of said units having a stroke substantially equal to the length of said working range,

contact means on the other platen spaced from said compensating units at the start of a platenstrokeso las to engage said units at a predetermined position of the movaable platen substantially only within said working range, a series of intermediate fluid operated cylinders, a series of pistons coacting with said intermediate cylinders, a fixed frame :carrying one of said series, a single crosshead movable on said frame and carrying the other of said series, a plurality of uid connections, each of said tiuid connections joining one of said compensating cylin-V ders to one of said intermediate cylinders, `an additional cylinder and piston assembly connected to said single cross-head, and a source of primary uid pressure connected to said additional cylinder to actuate Vsaid crosshead and thereby generate pressures in said intermediate cylinders and ycompensating cylinders for opposing tilt of said movable platen.

3. In a hydraulic press, a xed platen, a platen movable along a predetermined axis through an approach range and a working range, one of said platens being adapted to support a work-piece thereon, a plurality of pairs of uid operated compensating cylinder and piston units mounted on one of said platens and responsive to tilt of said movable platen, each of said units having a stroke substantially equal to the length of said working range, contact means on the other platen spaced from said compensating units at the start of a platen stroke so as to engage said units at a predetermined position of the movable platen substantially only within said working range, a series of pairs of intermediate fluid operated cylinders, the cylinders of each pair being arranged at diametrically opposite points with respect to a second predetermined axis,a series `of pistons coacting with said intermediate cylinders, a xed frame carrying one of said series, a single cross-head movable on said frame and carrying the other of said series, a plurality of uid connections, each of said uid connections joining one of said compensating cylinders to one 0f said pairs of intermediate cylinders, and actuating means connected to said cross-head to generate pressures in said intermediate cylinders and compensating cylinders for opposing tilt of 5 said movable platen.

References Cited in the le of this patent UNITED STATES PATENTS 2,283,447 MacMiuin et al. May 19, 1942 10 6 MacMillin et al Nov. 17, 1942 Bench Feb. 29, 1944 Monier June 6, 1944 Collins May 21, 1946 Waldie Aug. 28, 1951 Broekhoven et al Aug. 21, 1956 FOREIGN PATENTS Netherlands Apr. 15, 1943