US2968093A

US2968093A - Method of coining metal blanks for making cartridge casings

Info

Publication number: US2968093A
Application number: US292158A
Authority: US
Inventors: Lyon George Albert
Original assignee: Individual
Current assignee: Individual
Priority date: 1952-06-06
Filing date: 1952-06-06
Publication date: 1961-01-17
Anticipated expiration: 1978-01-17

Description

comma METAL BLANKS FOR MAKING CARTRIDGECASINGS Jan. 17, 1961 METHOD OF L A x r 7/ h A 1. A Z? JE'ZVEHZTZP:

Jan. 17, 1961 G. A. LYON 2,968,093

METHOD OF COINING METAL BLANKS FOR MAKING CARTRIDGE CASINGS Filed June 6, 1952 2 Sheets-Sheet 2 E 722mg:

United States Patent METHOD OF COINING METAL BLANKS FOR MAKING CARTRIDGE CASINGS George Albert Lyon, 13881 W. Chicago Blvd.,

7 Detroit, Mich.

' Filed June 6, 1952, Ser. No. 292,158

2 Claims. (Cl. 29534) The present invention relates to the coining of metal blanks, and more particularly concerns the making of button-like disks of metal from polygonal starting blanks as the initial step in the conversion of a flat metallic blank into a shell casing.

In the production of shell casings the metallic blank must be cupped and the side wall of the casing drawn by successive drawing steps. In the course of this drawing process, the marginal portions of the blank, which provide the metal for the side walls of the shell casing, are subjected to severe elongation.

Especially with certain materials such as hard brass and steel the problem of rupturing of the material during the draws, and especially during the preliminary draws, is a substantial problem.

It is accordingly an important object of the present invention to effect improvements in the initial coining of ametallic blank which is subsequently to be drawn into a shell casing, and more particularly an ordnance shell casing.

Another object of the invention is to provide an improved method of coining a metallic blank to prepare the same for efficient cupping and drawing into a shell casing.

Other objects, features and advantages of the present invention will be readily apparent from the following detailed description of certain preferred embodiments therei'ice 2 center. By preference, the edges of the coined blank intervening between the corners of the original blank are radially extended beyond the original outline of the blank so that maximum use is made of the material in blank and only corner portions need be trimmed away as scrap to provide a circular button-like disk ready to be cupped and drawn into shell casing form. The thinned, tapering margins of the coined blank disk lend themselves readily to the necessary elongation during the drawing process, while the thickened, domed central portion of the disk blank provides necessary material for the usual heading which a shell casing undergoes.

It has been found in practice that shell casings made according to the present method from unhardened nonspheroidized steel are unusually efiicient in practice. Such shell casings can be fired without hardening and will withstand pressures substantially in excess of service pressures. For example, 3.50 inch shell casings made from non-spheroidized steel coined according to the present invention and unhardened have been fired with charges creating up to 23 tons per square inch internal pressure, which is five tons per square inch in excess of service pressure of 17 tons per square inch. In fact, in tests conducted under these conditions such shell casings have survived repeated firings. That is, after initial firing they have been repeatedly recharged and refired, the casings holding up with such unusual lack of distortion that they permitted ready rechambering in the gun after the firings.

These new and unexpected results I attribute in a large measure to the initial coining of the blank in accordance with the present invention. The coined blank resulting from the method of the present invention appears to of taken in conjunction with the accompanying drawings in which:

Figure l is a fragmentary diametrical sectional view taken through a coining die apparatus and a metallic blank coined therein, and embodying the features of the present invention;

- Figure 2 is a top plan view of the coining apparatus and the blank therein after completion of the coining operation and with the upper or male die member removed;

. Figure 3 is a fragmentary diametrical sectional view taken through a modified form of the coining apparatus showing a metallic blank coined therein; and

Figure 4 is a top plan view of the coining apparatus of Figure 3 showing the coined blank therein and with the upper or male die member removed.

As shown on the drawings:

In the apparatus of Figures 1 and 2, three principal components are utilized, namely, a base or anvil die structure 10, a female or circumscribing ring die structure 11 and a male die structure 12. These die structures cooperate in the practice of the improved method of the present invention.

Primarily, the method of the present invention comprises subjecting a polygonal blank of metallic material, such as steel to uniform marginal pressure coincident with central doming of the blank to squeeze the marginal portions of the blank to substantially thinner tapered form while leaving the central portion of the blank at least in the original thickness of the blank and preferably somewhat thickened by displacement of some of the material from the marginal portion of the blank toward the have the grain structure properly aligned and the masses of metal in the various portions of the coined blank properly distributed so that in the several successive draws in formingthe shell casing uniform elongation with uniform yield and tensile strength are present in the casing and more especially in the pressure area of the side wall adjacent to the head end of the shell where the internal pressures are encountered in their severest form during firing.

My present method will be better understood as description of the structure and functioning of the coining die structures proceeds.

The base or anvil die structure 10 is preferably adapted to be mounted solidly on the bed of a coining press. For coining steel blanks adapted for 3.50 inch ordnance shell casings, non-spheroidized steel is used. The steel is supplied in rolled slabs from which polygonal blanks of appropriate size are cut and then coined according to the present method under coining pressures up to 4000 tons per square inch.

The upper portion of the anvil die member 10 is preferably of cylindrical form providing a cylindrical surface 13 merging upon a radius with a fiat horizontal surface 14 provided with a central blank-doming node 15. The node 15 has a central convex surface 17 preferably formed on uniform radius merging with a marginal preferably frustoconical surface 18 that converges with the horizontal sur face 14 on a radius juncture 19.

The ring die member 11 has a marginal skirt 20 of an internal diameter to engage about the cylindrical surface 13 of the anvil die member, while a flat ring body 21 of the ring die member extends in overlying relation upon the horizontal surface 14 to an internal ring diameter larger than the diameter of the doming node 15 and providing a preferably cylindrical female die surface 22 in predetermined coaxial spaced relation to the juncture 19. At its upper edge, the cylindrical die surface 22 joins the upper face of the ring die body portion 2 1 on a convex radius juncture 23.

A metallic blank B to be coined may originally be of square outline, and with the corners extending to a slightly greater diameter than the diameter of the cylindrical female die forming surface 22.

Normally the male die member 12 or coining punch structure is raised above the assembly of the die anvil and the ring die 11. Upon motivation in the press, the punch die member 12 descends upon the uncoined blank B and drives it into the cavity provided by the cooperating anvil die 10 and ring die 11. For this purpose, the punch die member 12 has a coining protrusion or nose 24 of smaller outside diameter than the diameter of the ring die surface 22 and preferably tapering to a substantially smaller outside diameter on a frusto-conical tapering surface 25 which at the tip of the nose portion 24 merges with a convex radius rib 27 substantially complementary to the radius groove 19 on the anvil die member.

The coining die nose portion 24 is hollowed out or provided with a cavity which is substantially comple mentary to the coining or doming node 15. To this end, the cavity within the coining nose portion is provided with a preferably frusto-conical marginal coining surface 28 which is formed at a slightly greater angle to the axis of the die assembly than the frusto-conical forming surface 18 of the doming node. The central portion of the punch nose cavity is provided with a preferably concave surface 29 opposing the convex surface 17 in preferably slightly greater spacing at the conclusion of the coining stroke than the original thickness of the blank B. The limit of the coining stroke may be determined by engagement of a stop surface 30 on the punch die 12 against the upper surface of the ring die body 21, while centering of the punch is effected by engagement of cylindrical external surface 31 thereof withn an upstanding cylindrical guide flange 32 on the periphery of the ring die member 11.

In the operation of the die mechanism, the polygonal metallic blank B, as shown in dash outline in Figure 2, is placed in centered position over the die cavity and the punch die member 12 is then brought to bear against the blank with the annular nose rib 27 driving against the blank uniformly. As the blank is pressed inwardly, the corners of the blank wipe down over the lead-in radius shoulder 23 and down along the die ring wall 22 and turn up somewhat in the restricted space as shown in Figures 1 and 2, being accommodated in the annular clearance between the ring wall 22 and the tapered nose surface 25.

In the continuing pressure movement of the punch die 12, the blank B comes centrally against the peak or crown 17 of the doming node and as the margin of the blank is depressed by the punch die nose 24 the central portion of the blank is accommodate within the cavity in the punch die nose. After the blank B has been fully pressed and bent against the node 15, the punch die 12 still continues in its coining stroke as permitted by the differential cavity size in the coining nose 24 and the coining rib 27 presses against the corner marginal portions of the blank to squeeze and coin and displace metal laterally and radially. Then the opposing convergingly

related coining surfaces

18 and 28 squeeze the tapering marginal area of the blank concentric with the coining rib 27 to a uniform tapered condition, displacing metal laterally and radially inwardly to the limit of the coining stroke of the die punch 12 as determined when it comes to a stop against the ring die body portion 21.

At the conclusion of the coining stroke of the die members, the result is as shown in full lines in Figures 1 and 2 wherein the coining rib 27 has pressed an arcuate channel 33 in the corner portions of the blank and action of the cooperating frusto-

conical coining surfaces

18 and 28 has uniformly tapered the marginal portion of the generally dished or domed blank to a substantial width and merging with a concave-convex central portion of slightly greater thickness than the thickness of the original blank due to displacement of material of the blank radially inwardly, during the coining operation. Also, the sides of the blank intermediate the corners have been coined radially outwardly to a substantial extent to provide a substantially circular outline coincident with a circle through the channels or grooves 33 at the corner marginal portions of the blank. Thereby, maximum use is made of the material in the blank and only a minimum scrap will result from trimming off the corner portions on the circular outline of the periphery provided intermediate the corners as the result of the coining. After the trimming of the corner portions, a circular disk button-like blank of dished shape is provided in which the margins taper gradually from substantially thinner than the original blank to a center that is thicker than the original blank. The coined dished blank is now ready for cupping and drawing into the shell casing form.

- By having the central cavity surface 29 of the punch die so related to the doming or dishing node 15 that in the bottom or at the end of the coining stroke at least slightly greater spacing will prevail between the

surfaces

17 and 29 than the original thickness of the blank, internal pressures in the die are avoided by accommodating displaced material at the central portion of the blank without coining pressure thereagainst. This is of great importance where large pressures on the order of 3000 to 4000 tons and upwardly are employed. Not only are damaging internal pressures in the opposing punch and anvil die areas avoided, but redistribution of the coined metal of the blank by flowing of the metal under pressure between the marginal coining surfaces is implemented and facilitated and substantial uniformity in the grain structure of the coined blank is attained.

In Figure 1 a somewhat exaggerated clearance 34 is shown between the convex surface of the coined blank B and the cavity surface 29, but it will be appreciated that in actual practice this clearance may be such that it just barely avoids pressure against the surface of the blank in the central crown area thereof.

In the modification of Figures 3 and 4, a coining die assembly 38 is shown including a lower base or anvil die member 39, a ring die member 40 providing a female die structure, and a male coining die member or punch 41. An indexing plate 43 supports and indexes the ring die member 40.

For concentric registration the upper end portion of the anvil die member 39 is formed cylindrical as indicated at 44 to fit within a complementary circular counterbore 45 in the ring die member 40. The coining face or nose end of the male die member 41 is formed cylin drical as indicated at 47 to fit slidably within a complementary circular counterbore 48 in the upper side of the ring die member 40. The upper edge of the counterbore 45 is formed on an entry bevel 49.

The female die ring member 40 has a lateral flange formation 50 overlying the margin of the indexing plate 43 surrounding a clearance aperture 51 therein. A series of alternating downwardly opening socket bores 52 and through bores 53 are receptive of spacer coil springs 54 and headed guide pins 55, respectively. Thereby, the coil springs 54 act to lift the ring member 40 into spaced relation to the anvil die member 39 to facilitate separation of the ring member from the anvil die member following a coining operation.

During a coining operation, the index plate 43 with the female ring die member 40 is placed in registration with the anvil die member 39, and a metal blank 8' of originally polygonal form is placed within the ring die member with the corners of the blank adjacent to a circumscribing ring die cavity wall 57, with the lower face or the base of the blank opposing the upper face of the anvil die member, identified at 58. As shown this coining face is flat.

:' The male die member 41 is driven toward positioned blank in the ring die member and the cylindrical portion 47 enters into the counterbore 48. This causes an annular coining ridge 59 concentric with the coining face of the member 41 and of smaller diameter than the diameter of the ring cavity wall 57, to press against the metal blank B. The substantial clearance afforded between the external diameter of the rib 59 and the opposing circular, cylindrical surface 57 of the ring die affords space into which the corner portions of the margin of the blank are accommodated freely.

From the outer periphery of the coining rib 5.9, a generally frusto-conical coining surface 60 extends radially inwardly and merges with a curved, convex cross-sectional surface 61, in turn merging with a cavity roof surface 62 from which may lead an air exhaust duct 63. It will be observed that the coining surface 60 is convergently related to the coining surface 58 of the anvil die member. Hence, as the coining stroke of the male punch member 41 progresses, in pressing relation to the blank B, metal in the peripheral area engaged by the coining surface 60 is displaced radially inwardly and slightly radially outwardly and a tapered margin is formed on the blank. Some of the displaced metal is crowded about the corners of the original blank as lobes (Fig. 4) to presently anchor the corner portions of the blank against the ring die surface 57 so that after the coining operation the coined blank will be lifted from the anvil die member 39 by raising of the ring die member 50 through the action of the springs 54.

By reason of the substantial cavity within the nose portion of the male die member 41, inside the coining ridge or rib 59, displacement of metal inwardly is accommodated without back pressure and the resulting coined button-like disk will have a tapered margin and a centrally thickened portion.

After the blank B is coined, it is ready to be trimmed within the outline of the outer periphery of the coining rib 59 impressed thereon and appearing as an annular channel or groove 65. Thereafter, the coined and trimmed blank disc is adapted to be subjected to suecessive cupping and drawing operations to provide a shell casing.

In both of the forms of die mechanism of Figures 1 and 3, the female or ring die members have the coined blank corners jammed against the ring die walls thereof so that the blank can be transported to appropriate trimming mechanism in the ring die member after the ring die member is lifted off of the anvil die member.

It will be understood that modifications and variations may be effected without departing from the scope of the novel concepts of the present invention.

I claim as my invention:

1. In a method of coining polygonal metal blanks preparatory to drawing of the blanks into shell casings, placing the blanks over a cylindrical die member of smaller diameter than the diameter of a circle about the corners of the blank and with the corner portions of the blank lying upon the die member in substantially centered relation, and driving the blank into the cylindrical die member and thereby wiping the corners of the blank longitudinally along the cylindrical wall of the die member and bending the corners angularly to substantially jammingly fix the blank within the die member for coining and trimming operations within the die member.

2. A coined blank of metal adapted for drawing into elongated shell form, said blank comprising a central circular concave convex portion of substantial thickness,

and an annular margin of substantial width tapering.

frusto-conically from said central portion with diminishing thickness in cross-section from the central portion to the extremity of the marginal portion, and joining the central portion on a uniform radius both inside and outside of said dished blank, with the grain structure of the blank properly aligned and the masses of metal in the various portions of the blank properly distributed so that in the several successive draws to which the tapered marginal portion is adapted to be subjected in forming a shell uniform elongation with uniform yield and tensile strength will be attained and more especially in the side wall of the shell adjacent to the head end of the shell.

References Cited in the file of this patent UNITED STATES PATENTS 1,650,055 Tregillus Nov. 22, 1927 2,106,647 Neck Jan. 25, 1938 2,360,354 Lyon Oct. 17, 1944 2,601,029 King June 17, 1952 2,608,352 Schuster Aug. 26, 1952 FOREIGN PATENTS 24,248 Great Britain Nov. 1, 1911