US2878767A - Forming press diaphragm - Google Patents

Description

f March 214, 1959 Filed Jan. 4. 1954 2 sheets-Sheet 1 March 24, 1959 R. A. PAULTON l 2,878,767

FORMI'NG PRESS DIAPHRAGM Filed Jan. 4, 1954 2 Sheets-Sheet 2 1N V EN TOR.

ZO /L\ T TORNE Y6.

FORMING PRESS DIAPHRAGM Richard A. Panlton, Cozaddale, Ohio, assignor to The Cincinnati Milling Machine Co., Cincinnati, Ohio, a corporation of Ohio Application January 4, 1954, Serial No. 402,079

3 Claims. (Cl. 113-44) This invention relates to improvements in hydraulic forming presses and has particular reference to a novel and improved diaphragm and diaphragm mounting structure.

One of the objects of the present invention is the pro vision of an improved simplified form of diaphragm for use in connection with high pressure metal shaping or forming operations.

A further object of the invention is the provision in connection with such a diaphragm of improved mounting and retaining means for insuring proper retention of the diaphragm within the forming head or pressure dome of a hydraulic forming press in a manner to allow adequate yielding of the diaphragm during a forming operation while insuring a non-leaking seal between the diaphragm structure and the forming head under high operating pressure conditions.

A further object of the invention is the provision of improved sealing and retaining means of a simplified but efr'cient character for securing the parts in assembled relation under non-pressure conditions.

Other objects and advantages of the present invention should be readily apparent by reference to the following specification, considered in conjunction with the accompanying drawings forming a part thereof, and it is to be understood that any modifications may be made in the exact structural details there shown and described, within the scope of the appended claims, without departing from or exceeding the spirit of the invention.

Figure l is a fragmentary sectional view of a hydraulic forming press structure illustrating one form of the present invention.

Figure 2 is a similar View of a more simplified form thereof, and

Figure 3 is a fragmentary section of an interlock dia- -phragm retaining structure.

The present invention is particularly adaptable for use in connection with present commercially known hydraulic forming presses, as for example, the Hydro-Form machine manufactured by T he Cincinnati Milling Machine Co. Such a press includes a pair of relatively shiftable elements such as the nest plate 10, ordinarily supported by the bed of the machine and the movable dome element or forming head 11 having a central cavity or recess as at 12. This recess is enclosed by an inner wall surface including side wall portions 13 extending substantially parallel to the central axis of the recess which blend with an upper domed portion 14, the two together providing an open end recess for reception of uid or hydraulic pressure medium which may be introduced or exhausted from the recess or chamber 12 by way of the pipe or conduit 15. In operation, this pressure may run as high as 10,000 to 15,000 pounds to the square inch. In the use of such a press the work piece 16 to be formed is placed on the upper face of the nest plate in overlying relation to the independently shiftable punch or die element 17. When the elements 10 and 11 are in their closed position, the pad portion 18 of the present improved diaphragm ta. Patent Vice is forced down against the work piece and into engagement with the member 10 in circumscribing relation to the work piece. The parts are then locked in this position, an adequate pressure created in the chamber or recess 12, and the punch 17 then moved upwardly against the Work piece. The pressure in the chamber 12, which may be 10,000 or more pounds to the square inch, is adequate in amount to hold the peripheral portion of the work piece down against the nest 10 as the punch is moved upwardly so that the central portion is shaped by the diaphragm around the punch in a smooth owing manner While the outer portion of the pad is retained in engagement with the nest 10.

Depending on the size of the punch, and the depth of the draw, the extrusion of the punch and work piece into the recess may be entirely taken up by material flow within the pad, or as the draw becomes deeper there may be a tendency of the outer edge of the pad to be pulled inwardly. In previous press structures of this character it has been considered necessary to mechanically lock the peripheral portion of the pad rmly to the die member 11 to retain the same in position, both when in raised position with respect to the Work and also when in forming position and to insure adequate seal between the pad and the die member to prevent improper extrusion of the pad under pressure or escape of the pressure fluid from the recess.

This has resulted in a tendency toward tearing of the periphery of the diaphragm at such securing means, lessening the life of the structure and requiring the employment of complicated securing means to withstand the pressures developed, thus involving considerable loss of time in removal and replacement of a worn or damaged diaphragm.

The present invention and discovery relates to a dial phragm structure which can be satisfactorily utilized under extreme high pressure operation conditions, which can be readily removed and replaced, which will provide a perfect seal against escape of the compressed operating fluid and which will not be subject to the tearing strains and conditions existing with prior art structures.

In the present instance, the main pad portion 18 has been illustrated as formed with an upstanding rim or flange 19, the parts being of rubber or like ilexible and compressible material. The flange 19 is preferably initially formed substantially of the diameter indicated of the lower portion of the pad so that when forced upward and into interlitting engagement with the side wall portions 13 of the inner wall surface it will be under compression, tightly interlocking with the wall 13 to provide an airtight seal and resist withdrawal from the recess. To facilitate this introduction of the diaphragm the die head 11 is preferably provided with a plate 20 having an inwardly aring recess 21 tapering upwardly and into alignment with the wall 13 of the main die head and itself closely embracing the outer periphery of the main thick or heavy pressure pad section 1S.

Intermediately of its length the rim or flange section 19 is provided with the inwardly extending relatively rigid stitfening bead 22, the thickness of the portion of the rim or flange 19 as at 23 between the bead 22 and the pad section 18 being appreciably less than the thickness of either the work engaging pad or that of the flange at the bead to insure improved flexibility and potential eX- terminal shoulder portion at 24 interlocking with either the abutment or shoulder 25 formed in the die member f 11 or alternatively with the annular abutment or shoulder 26 of the limiting ring 27 which engages the upper end orI rim of said annular ange.

If the shoulder is formed directly in the die member 1,1, as shown in Figure 2, this forms a definitely positioned stop peripherally limiting the upward movement of the diaphragm member, either in a direct axial direction or by tilting. If the, stop is in the form of the ring 27 shown in Figure 1, it may correspondingly directly control the position of the diaphragm at a definite point if the ring is secured to the die member. Alternatively, and

as particularly illustrated in Figure 1, the ring may have` a slightiioatiug movement. In this instance, the diaphragm can slide upward slightly before the upper edge of the ring contacts with and is limited in its movement by engagement with the dome portion of the recess, while, alternatively, when upward pressure against the diaphragm isk released it will follow down with any downward movement of the diaphragm tending to maintain the same level.

As illustrated, there has been shown as secured to and depending-from the plate the annulus 28 circumscribingl the punch nest 10 when the die elements are closed. This ring may betformed with one or more sockets 29, preferably several in number containing the abutment dogs 30 locked in position by set screws 31 and adapted to engage the lower edge of the floating diaphragm retaining ring 32 which lies under the peripheral edge portion of the pad 18. This ring, as shown, has a close sliding fit at 33 with the inner cylindrical wall 34 of the plate 20, and has the depending flange 35 adapted to rest upon the nest 10. When the die elements are closed, the ring 3 2 is pressed upward, sliding on the inner wall of the plate 20, its beveled edge 36 engaging and upwardly compressing the peripheral edge of pad 13 providing a tight seal to prevent extrusion of the edge of the pad when under pressure, but being supported for a yielding movement to accommodate itself to any minute relative shiftings of the members 10 and 11 during the forming operation. When the die elements are separated, the dogs 30 limit the downward movement of the ring and therefore any possible downward slippage of the diaphragm. However, when it is desired to remove and replace the diaphragm it is merely necessary to loosen the set screws 31 and retract the dogs 30 and the ringl may be readily slipped out of position and the diaphragm itself then withdrawn and a new one inserted.

There are three basic and different conditions under whiehthe diaphragm must be retained and, of course, at i all times the diaphragm must seal the pressure dome so that the entrapped oil or tiuid, under pressure or otherwise, willnot leak out. These conditions are as follows: (1)` loading-dome in raised position, no pressure in dome;v(2) dome down in forming position with oil pressures exceeding 15,000 p.s.i.; and (3) dome down after forming, but oil having been exhausted to 0 pressure. This latter condition leaves diaphragm extended over finished part and presents a very severe condition, both from stretch on the rubber and oil sealing.

T he present invention meets and satisfies the requirements of the above-mentioned conditions. Specifically, the dome 12 in the main body 11 constitutes an oil cavity, and the diaphragm structure 18-19 forms a liexible die member which will seal the oil in the dome cavity 12 under all conditions.

These two parts are the main components and function thusly. The cavity is machined or cored in the domeand the walls may be tapered or straight, depending upon the strengthrequired in the dome. The diaphragm can be of any rubber or rubber-like material which meets the conditions of abrasion, stretch, and resistance to oils desired, which, of course, governs the lifeof such substance during repeated operations.

The diaphragm is inserted into the cavity in such a manner that there is enough initial tension against the sidesof -the cavity to prevent air from entering the cavity. This-is-veryimportant because, as previously stated, the diaphragm is free to move,

theioilfidthe: dome to.fall out. I-Iowever.,.the.initial and*v could fall out allowing;

pressure on the sides of the walls form an airtight chamber and as the weight of the oil and diaphragm tends to cause the diaphragm to move down, a vacuum is formed, thereby retaining the oil and the diaphragm in the raised position.

In the forming position, the initial pressure of the diaphragm iiange against the sides of the cavity allows the pressure tobuild up on the inside of the diaphragm, forcing the diaphragm rim or tiange against the cavity walls, effectively sealing the dome during forming pressures from 0 to 15,000 p.s.i.

lt may be noted that, since the diaphragm is an unclamped member, the lower portion can peel away from the sides of the cavity, allowing much less strain on the diaphragm during severe deep draws, and at the same time retaining the oil.

When the dome is down and the pressure has been exhausted in the dome cavity, the diaphragm` can slide up into the dome cavity if the sides are straight, thereby relieving the stretch andvstill retaining the oil. If the sides of the cavity are tapered the diaphragm can peel off at the bottom, accomplishing the same purpose. i

The above covers the basic construction of the unclamped or cup-shaped diaphragm assembly, but for long life of the diaphragm and to ease manufacturing tolerances, some additional parts are used in the assembly.

An important part is the oating ring 32. This ring of solid material spans the gap between the Sides of the dome cavity and the nest plate. Unless this gap was held to a few thousandths of an inch, during forming under high pressures, the diaphragm would extrude, shortening the life of the diaphragm.

In order to assure the diaphragm being level at all times, especially during the time that the domeis coming down on the blank, retaining ring 27 is used. It can eitherbe bolted to the inside of the dome cavity or can lay loose on top of the diaphragm as shown in the drawing.

When coming down on a preformed part on a deep drawn part, if not restrained in some manner, the diaphragm might turn inside out. To prevent action of this sort inthe form of the invention shown in Figure 2, there has been provided the stilening bead 22 and intermediate thinner iiexible portion 23 of the rim of the diaphragm. This stilfening bead serves to hold the upper portion of the diaphragm rim tightly against the inner wall of the dome to prevent such action. In the event of possibility of more extreme strains on therdiaphragm, use may be made of the supplemental` restrain.- ing ring 37 as illustrated in Figure l which is loosely and removably mounted within the diaphragm intermediateV the'rib 22. and the pad 18, the spacing relationship between the exterior of the ring and the inner face of the rim or flange on the diaphragm as well as the spacing relation between the rib 22 and pad 1S with respect to the width or height of the floating ring 37 being such as to permit of a certain amount of yielding and stretching of the intermediate thinner portion 23 so that the diaphragm, as an entirety, may properly accommodate itself to the stretching and displacements effected as by the punch 17 while itse general movement is limited by the interengagement of the bead 22 with the restraining ring, so that possibility of disengagement of the upper portion of the retaining flange with respect to the inner wall of the dome, even under most extreme conditions, is prevented.

In Figure 3 the upper abutment ring 27 has been illustrated as secured to the wall of the dome by the fastenings 38. This ring, as indicated in both Figures 1 and 3, has the downwardly extending inner tiange portion 39 spaced from the wall of the dome to provide a peripheral recess receiving the upper edge or shoulder portion 24 of the rim of the diaphragm. In Figure 3, the depending flange 39 is formed with the outwardly extending double tapered header rib t0-projecting toward but in spaced;

relation to the wall 13 of the dome and adapted to t into the groove 41 in the flange of the pad. In assembling the inwardly extending compressible rib 42 on the diaphragm it is forced upward past the rib 40 which provides a narrow entrance throat for the recess 43. As it is forced up into the dome, rib 42 will spring into and extend within the recess 43 between the ange 39 and shoulder 26 on the rim and annular wall 13. This may be readily effected by partially inserting the flange of the diaphragm into the dome recess and then closing together the die element 11 and the nest plate 10 providing the necessary force to move the parts into assembled relation shown in Figure 3. This structure has the additional advantage over those previously described of providing a mechanical interlock between the retaining ring and the diaphragm which will permit a certain amount of free or unrestricted relative movement of the diaphragm and the dome while the interengagement of the parts will aid in mechanically holding the diaphragm in position when the dome is raised to prevent separation or relative tilting of the parts. For removal, the dome is preferably slightly raised and sucient pressure built up in the enclosed dome area to aid in snapping the diaphragm out of the dome. It will be understood that relatively low air pressure will be adequate for this purpose, avoiding the possible loss of the oil or hydraulic medium normally employed for forming pressure creating purposes.

It will be ovious that the double tapered form of the bead or ange 40 facilitates initial positioning of the diaphragm prior to the snap of its bead 42 into the recess 43.

What is claimed is:

1. A die element for a cyclically operable forming press comprising a hollow pressure dome having an inner wall surface enclosing an open end recess in the dome for receiving liquid under pressure, said wall surface including side wall portions extending substantially parallel to the longitudinal axis of the recess, a flexible closure for the open end of said recess mounted for bodily sliding movement therein during the press cycle when pressure is removed from the liquid, said closure including a thick resilient pad portion of substantially uniform thickness peripherally interiitting with said side wall portions of the inner wall surface to close the recess against the escape of liquid therefrom and having an upstanding annular ange extending normal to said pad portion adapted for intertting sliding engagement with said side wall portions, the length of said ilange being less than that of said side wall portions so as to permit sliding movement of the closure within the recess during a press cycle to prevent the inner end of the ange from separating from the side wall portions of the recess and breaking the liquid seal when pressure is removed from the liquid in the recess and a formed or preformed part is projecting up into the recess, and means in said recess lying in a plane perpendicular to the longitudinal axis of said recess for engaging the inner end of said ange to limit sliding movement of the closure into the recess to the contines of the parallel side wall portions of the recess and also to prevent cocking of the closure within the recess.

2. The die element of claim 1 including sealing means for preventing extrusion of said closure around the peripheral edge of said pad portion, said means comprising a oating ring located inthe mouth of said recess beneath said closure and extending around the periphery thereof, said ring having a peripheral face thereon which is adapted for interltting sliding engagement with said side wall portions of the inner wall surface to provide support for said ring in the mouth of said recess, and an annular face thereon inclined with respect to said peripheral face which is adapted to engage the face of said pad portion around the peripheral edge thereof and seal the same against extrusion from the recess.

3. The die element of claim 2 including a nest mov-able with respect to said dome for closing the open end of the recess therein, and an abutment surface on said ring for contacting a mating surface on said nest to hold the ring within the recess when pressure is applied to said dome.

References Cited in the le of this patent UNITED STATES PATENTS 2,204,648 Baker June 18, 1940 2,385,083 Kemerer Sept. 18, 1945 2,550,672 Chyba May 1, 1951 2,771,850 Wheelon Nov. 27, 1956 2,783,727 Hoffman Mar. 5, 1957

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