US2360353A

US2360353A - Method of making cartridge casings

Info

Publication number: US2360353A
Application number: US408193A
Authority: US
Inventors: Lyon George Albert
Original assignee: Individual
Current assignee: Individual
Priority date: 1941-08-25
Filing date: 1941-08-25
Publication date: 1944-10-17
Anticipated expiration: 1961-10-17

Description

Oct. 17, 1944. G. A. LYON 2,360,353

METHOD OF MAKING CARTRIDGE CASINGS N W l Filed Aug. 25, 1941 2 Sheets-Sheet 1 .ZEH W Q5.

.Oct. 17, 1944. v G. A. LYON 2,360,353

METHOD OF MAKING CARTRIDGE CASINGS Filed Aug. 25, 1941 2 Sheets-Sheet 2 GEO/PG; ALBf/QT Zro/v.

Fig. If. fig. /Z. fig. L3.

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L g a a 5 46 43" 46 J0 4 g g VE' U Patented Oct. 17, 1944 UNITED STATES PATENT OFFICE 9 Claims.

This invention relates to a method of manufacturing cartridge cases or casings, as well as to a die for use in the practice of the method.

The present subject matter constitutes a con tinuation in part of my copending application, United States Serial No. 404,208, filed July 26, 1941.

Cartridge cases for present day rapid fire guns characterized by high muzzle velocities, for instance, the 40 m. m. Bofors anti-aircraft gun, are required to resist great stresses during loading, firing and extraction. These stresses are concentrated in the head or closed end of the cartridge case, whose bottom consequently must be made much thicker than the side walls. The latter, of course, are made as thin as possible to keep down the weight of the cartridge.

Heretofore, in the manufacture of '40 m. m. Bofors cartridge casings and the like, it has been the practice to punch circular blanks each of which is of a predetermined weight and metal content commensurate with the size of the easing to be made therefrom by subsequent cupping of the blanks and drawing of the side walls of the resultant cups. has convenionally been obtained by either of two methods. In one method, the original blank is punched from a sheet having a thickness equal to the required bottom thickness of the casing which requires that after the cupping operation the heavy side walls of the resultant cup be drawn out to form the thin side walls of the finished cartridge case. A thick-bottomed casing has also been fabricated by punching out the circular blanks from relatively thinner sheet metal and, after cupping, building up the metal in the bottom of the casing by indenting operations. In the latter method, the drawing out of the side walls need not be as severe an operation as when a cupped thick blank is drawn.

However, certain disadvantages are inherent in both these prior art methods.

When blanks are cut from thick metal stock, the cutting or punching of the thick sheets results in a socalled drag on the material at the edge being out, which is made evident by roughness and the presence of slivers of free metal and burrs at the cut edge. The structure of the marginal blank portion is also made irregula" for some distance inward. These irreguarities remain in the margin of the punched-out -u rt through all the subsequent cupping and "rawirg operations. As a consequence, it has heretofore been found necessary to draw out the casing to a length much greater than that de- The required thick bottom sired in the final cartridge and then to cut off between 4 and 5 inches of the open end so as to remove from the casing material characterized by a roughened surface, overlapping seams, and more or less free slivers or burrs of metal. Further, portions of this irregular or rough part of the blank are likely to break off in one of the drawing dies, and may then so damage the casing as to necessitate its rejection. Due to the rapidity with which these casings are drawn on a'large production basis, such a broken off piece of metal in the die, if not observed, might easily result in the damaging of many casings before its presence is detected.

In addition, if the blank is punched from thick sheet material, it may be necessary to anneal the blank in order to offset the hardening occasioned by the working of the material at the edge of the cut blank, since, otherwise, that edge will have a different degree of hardness than that of the center of the blank.

In the previous practice of fabricating cartridge cases from relatively thin sheet metal (which I understand has been recommended for adoption by the present Defense Administration for use in the manufacture of these casings), the first operation after the punching of the blank comprises a cupping operation. In this regard, I have noted that, due to the considerable thickness of the blank, the stock must be subjected to tremendous pressure and strains to bend and draw the blank into a cup having a thickened bottom and a thin wall. This very harsh working of the metal in the side walls results in a crystal or grain structure oriented vertically in the side walls of the cup. The bottom not being worked so severely, no corresponding structure is established therein. There is therefore established a line of potential structural weaknesses at the transition from the bottom to the walls of the cup.

If, on the other hand, the blanks are punched from sheet material thin enough to avoid the drag of the edges being cut, then large indents are required to build up a thick bottom for the cartridge cases that are diflicult and impractical from a commercial standpoint.

Punching out round blanks from sheet metal, as practiced in both prior art methods, wastes a large amount of material, for the round blanks can obviously not be punched out contiguously, but a network of sheet material is left between the punched-out perforations. In particular, when heavy sheet metal stock is used, it is necessary to space each blank a considerable distance from the adjoining blanks in order to have sufficient remaining material'for a hold-down during the cutting through of the thick stock. As a. consequence, there is as much as percent waste in the brass sheet from which the blanks are punched.

I propose to provide a new method of making integral cartridge cases having closed bottoms much thicker than the side walls .of the bases without including in my process either any cutting and sebsequent drawing out of thick sheet material or any difficult indenting of thin sheet material. More particularly, I propose to make cartridge cases having thick bottoms and thin side walls by coining polygonal blanks cut contiguously from thin sheet material between rounded dies encompassing all but the corners of the polygonal blanks, to outline on the blanks sub stantially circular disks having a thickened central portion and a thinner marginal portion. The corner parts not encompassed by the dies are then trimmed off and the coined and trimmed blank is cupped, the thickened central portion being formed into the dome-shaped bottom of the ensuing cup and the thin portion being formed into the side walls of the cup. These thin side walls may easily be extendedby a few drawing operations.

An object, therefore, of this invention is to provide an improved method of manufacturing cartridge cases with less waste and with fewer drawing operations.

Still another object of the present'invention is to provide a simple die for use in practicing my novel method.

It is also the aimof this invention to provide a method of coining easing disks from a blank of metal in such a way that all of the cut or sheared edges of the blank are either disposed or forced outside of the die during the coining operation so that such edges may be later trimmed off in the form of a flash, thereby not resulting in the ensuing article having any of the metal of the cut edges therein. I

In accordance with the general features of this invention, contiguous square or polygonal-shaped blanks are sheared from a cast flat slab of metal. Open cutting by shearing eliminates drag, for the metal can move away as it is being out. When punched, the metal is confined by the cutting member and dragged across and past the cut edge.

The square or polygonal blank is then placed in a round coining die of such size that all of the cut or sheared edges in the blank are disposed at or outside of the edges of the die'. More particularly, the edges of the polygonal blanks form tangents to the die. The metal, when pressed in this die, flows inwardly to form a circular disk having on each face a central protuberance tapering outwardly toward each margin of the blank. The corner portions of the blank which are outside of the die are not reduced in size but if anything are increased in size by reason of the crowding of metal therein. The edge of one die forms circular grooves on one face of the blank that. separate the outside corner portions and the edge portions of the blank from the coined disk within the die. at the bottom of these grooves is thinned and embrittled and may easily be cut through or sheared to separate the desired circular button from the sheared edges of the so-called flash outside the die without causing irregularities in the resultant round edges. In other words, all

of the material of the edges of the blank is outside of the circular disk to. be later formed into the casing and as a consequence external material or flash can be easily trimmed from the disk thereby preventing any of the irregularities of the rough sheared edges of the blank from being reproduced in the article as it-is later drawn.

The trimmed coined blank is more easily centered in the cupping die and, once centered, is more easily kept from sliding ofi center than the conventional round fiat blanks punched from thick sheet metal, for the central bulge of the coined blank serves as a centering means while its thin margins confer on the coined blanks a relatively larger area so that the clearance between the cupping die parts required for the insertion of .the blanks is taken up more completely and the tendency to slide off center is lessened. The punch of the cupping die also aids inkeeping the blank centered.

I In accordance with other features of this invention, the cup produced as aforesaid may thereafter be progressivelydrawn until the desired length of cartridge casing is obtained, without necessitating the cutting off of as much waste material at the open end of the casing as heretofore.

In accordance with still other features of the invention, the casing produced as aforesaid is thereafter subjected to an upsetting operation to flatten the bottom; there being less likelihood of ruptures of the metal due to a grain structure having been established in the cup bottom having substantially the same direction as that of the wall.

The casing is finally tapered to give the same the bottle-necked form typical of cartridge cases.

Other objects and features of this invention will more fully appear from the following more detailed description, taken in connection with the accompanying drawings, which illustrate a single embodiment of the invention, and in which:

Figure 1 is a plan view of a cast slab of brass showing, as cut therefrom, a strip adapted to be The metal sheared along dotted lines into pentagonal and hexagonal blanks and showing in other dotted lines how other such strips may be cut from the slab without any waste; v

Figure 2 is a fragmentary, vertical, cross-sectional view taken through'cooperable die members for practicing my novel method, and illustrating a blank in position therebetween after the coining and squeezing operation;

Figure 3 is a fragmentary plan view showing a blank in position above the lower of the two die members of Figure 3 preparatory to the coining operation;

Figure 4'is a side view, on a reduced scale, of a hexagonal blank showing its shape and configuration before the coining operation performed by the dies of Figures 2 and 3;

Figure 5 is a plan view, somewhat enlarged, of

the blank of Figure 4 after the coining operation;

Figure 6 is a vertical cross-sectional view, on a reduced scale, of the blank of Figures 4 and 5 after the coining operation and after the removal of the flash including the outer corner blank portions not encompassed within the round dies of Figures 2 and 3;

Figure 7 is a longitudinal cross-sectional view through the cupped article formed or drawn from the coined disk shown in Figure 6 as trimmed;

Figures 8, 9 and 10 are longitudinal cross-sectional views illustrating how the cup shown in Figure 7 is progressively drawn by a series of drawing operations to produce the desired length of easing, the dot and dash lines in Figure 10 delimiting the part of the open end of the casing which is cut off after the final draw;

Figure 11 is a longitudinal cross-sectional view through the article produced after the cutting off operation illustrated diagrammatically in Figure 10 and showing how the thickened end or bottom of the casing is upset and flattened, as well as indented;

Figure 12 is a longitudinal cross-sectional view showing how the article look after it has been subjected to the first tapering operation; and,

Figure 13 illustrates the final form of the easing after it has been subjected to additional tapering operations, as well as to the operation of head tapping to provide the usual primer hole; this figure also shows how the head is flanged.

It is believed that my novel process will be best understood from a description of the article as illustrated in the accompany drawings during its different stages of fabrication, as well as from a description of the apparatus for use in the practicing of the process.

It should be noted that the illustrations in the accompanying drawings are more or less diagrammatic and that, while I have illustrated a slab of a width such that a strip adapted to be sheared into four pentagonal and hexagonal blanks may be sheared therefrom, different slab widths could be used equally well. Each blank could also be cut singly from the slab.

Also, while my invention resides primarily in the process or method of making the casing, I

have evolved a new die particularly adapted for practicing the coining operation of my method.

In Figure l, the reference numeral l0 designates generally a cast slab of metal such as brass which has had both broad surfaces thereof planed to remove scratches and flaws. From this slab there is sheared by means of suitable equipment a strip l l formed so that when sheared along the transverse dotted lines hexagonal blanks such as the blank M of Figure 4 are obtained each containing enough metal to form a cartridge casing. As can be readily seen, there is no Waste of slab material. While the blanks are shown as cut collectively, single blanks may also be cut, and square or polygonal forms other than hexagons may be resorted to, for instance,

octagons.

As shown in Figure 1, the blanks sheared from the ends of the strip II are pentagonal rather than hexagonal. Hexagonal blanks of the same size as those out from the middle portions of the strip could be fashioned from these pentagonal blanks by additional shearing operations. Such shearing. however, is not necessary, for the pentagonal blanks lend themselves equally well as the hexagonal blanks to the subsequent coining. cupping, and drawing operations yielding the desired cartridge casing, as will be described in greater detail hereinbelow.

The material of the slab l0 may also be cold rolled from a brass casting to the proper thickness and milled to remove the check from the cast on both sides of the slab. If made from such material, the blank, after cutting, has to be annealed. whereas if the slab comprises a casting which has not been cold rolled, the cut blank may then be subjected to the first working or coining operation without the necessity for employing an intermediate annealing operation.

At this time, I desire to point out that incon- Ill) nection wiith any of the operations hereinafter described, it is the practice to anneal the article after each working or drawing operation so that the hardness picked up by the working of the metal can be offset before the next operation is carried on. After the final operations, the casing is subjected to a socalled normalizing operation at a given temperature for a predetermined length of time so as to cause the casingto have the requisite hardness required by Government specifications.

The thickness of the slab. of course, depends upon the size of the blank, the smaller the blank the thicker the slab and vice versa. At present, the Government specifications require the use of a round blank of approximately ,4; of an inch thick and 3% inches in diameter and which blank weighs approximately two pounds and four ounces. As noted before in punching round blanks from a brass slab, there is as much as 40 per cent waste, and the drag incident to the punching operation results in a roughened or irregular, as well as a slightly hardened, edge on the blank.

My present process in using a polygonal blank eliminates, to a large extent, the waste since I propose to use all the metal in each blank except the corner edge portions by coining the polygonal blank into a circular disk having appended thereto easily separable flash portions including the corner edge portions, this coining operation being effected prior to the cupping, operation, which at present is the fiist operation after cut ting the blank. In Figures 2 and 3. I have illustrated how the polygonal blank can be coined or squeezed into star shape, and in Figures 5 and 6 I have illustrated the appearance of the coined blank before and after removal of the flash as Well as the corner edge portions that form the points of the star.

In practicing the coining o squeezing operation, I can use a suitable press equipment provided with cooperable die members illustrated diagrammatically in Figure 2 and designated generally by the reference numerals l5 and IS. The upper die member l5 has a face with a shallow flat-bottomed central recess l1 and a rounded annular peripheral ridge l8 separated from the recess H by an annular frusto-conical surface I9 sloping gently toward the central recess, The lower die member I 6 is shaped with a shallow round-bottomed central recess 20 surrounded by an inwardly sloping frusto-conical annular surface 2I extending over the rest of the die face and having an outer edge aligned with the ridge l8. Outside the ridge l8 and the annular surface 2|, both die members are limited by frustoconical surfaces '22 that slope away from the die faces. The die faces within the frusto-conical surfaces 22 are ofsuch size that when the blank '4 is disposed between and concentrically with the die faces, the cut edges of the blank form.

tangents to the ridge l8 and the outer edge of the annular surfaces 2 I, as shown in Figure 3.

The die members l5 and I6 may be pierced by air vents 23.

The surfaces I9 and 2| are capable of being brought closer together than the two broad faces of the blank l4, and the two annular die surfaces slope inwardly. Consequently. when the blank I4 is squeezed by the (lie members, the blank metal Will flow inwardly an the b ank;, will be coined into the star-shaped article 25 illustrated in Figure 5. It should be clearly understood that the coining operation according to my process or method is performed prior to any cupping or drawing operations and is such that the subsequent cupping and drawing operations are not only facilitated but less stress and strains are imposed on the metal as it is cupped and drawn.

Now it will be observed from Figures 2 and 5 that all of the metal of the polygonal blank I4 has been utilized in the formation of the starshaped blank 25. This blank includes, besides a circular disk-like central portion 26, a thin marginal portion or flash 29 squeezed outwardly between the cooperating edges of the die member and which flash also includes the thicker marginal projections 21 derived from the corner portions of the blank l4 not encompassed by the ridge [8 and separated from the round center of the blank 25 by grooves 28. By trimming or shearing these slight marginal projections 21 and the flash 29 from the round center 26 along the grooves 28 of the blank 25, I am enabled to form the disk 30 of Figure 6 having a perfectly circular configuration. Any suitable trimming equipment may be used for this purpose. It should be noted from Figure 5 that the thin peripheral portions of material or flash 29 between the projections 21 is relatively thin and comprises the material which is squeezed outwardly between the cooperating edges of the cup-shaped die members l5 and I6. This results in all of the sheared edge portions of the original blank being disposed outside of the confines of the disk 25 from which the ensuing casing is to be drawn. As a consequence, by trimming off the portions 2'! and 29 the ensuing disk, as it is drawn, will not have any of the irregularities of the material that were present in the relatively thick edges of the original blank. It should also be noted that due to the portions 25 being relatively thin, such for example, as an eighth of an inch, the disk 25 has at its peripheral edge a relatively thin out edge after it is trimmed, which is decidedly advantageous.

The amount of waste ensuing from this trimbetween the cold working operations is well lmown in the art. After the disk 3| has been annealed, it is placed in suitable press equipment and is drawn into the shape of the cap designated generally by the reference numeral 88 in Figure 7. In this cup, it will be perceived that the thinner portion 33 of the disk 38 has been drawn into the wall 31 of the cup and the thick portions 3| and 32 have been formed into crown-shaped bottom 38 of the cup. In this cup, the lines of the grain structure extend from the center of the bottom around and up vertically through the side wall 3'! so that the lines of the crystals all extend in substantially the same direction. This eliminates a potential point of weakness at the Junction of the side wall I! and bottom 38 which might be present if the grain or crystal structure'of the metal was not all stressed in the same direction.

In Figures 8, 9 and 10, I have illustrated three different conditions of the cupped article as it is progressively subjected to a series of drawing operations for the purpose of elongating the wall to the length desired in the ultimate cartridge casing. The first condition of the cupped article, after it is subjected to the first drawing operation, is diagrammatically illustrated in Figure 8 and the ensuing product is designated by the reference character 39. Likewise, the article obtained after the third drawing operation is dis. grammatically shown in Figure 10 and is designated generally by the reference character 4|. The article 40 of Figure 9 illustrates the results of the second drawing operation.

As shown in Figures 8, 9 and 10, in the progressive cupping and drawing of' the blank 38 yielding an initial cup 36 having an outwardly beveled rim derived from the beveled lower marming operation is in the neighborhood of 5 to 10 per cent as compared with about 48 per cent waste in the case where round blanks are used.

The pentagonal blanks formed from the ends of the strip I i are worked similarly to the hexagonal blanks. The material which if trimmed off the pentagonal blanks would have left hexagonal blanks simply goes to enlarge slightly the projecting portions outside the grooves 28 which are trimmed off after the coining operation.

The blank 30 of Figure 6 is coined upside down. As shown in Figure 6 with the right side up, the coined blank includes a rounded central upper protuberance 3|, a lower flattened central protuberance 32, and an outer thinner marginal portion 33 having its lower outer edge beveled at 34.

From the foregoing, it is clear that the squeezing or coining operation causes a radial flow of the metal toward the center of the blank. Hence, the grain or crystal structure effected by this cold working operation takes the form of a pattern resembling the spokes of a wheel in that the lines of flow of the crystals extend to and converge-at the center of the blank. This fact is of importance in the subsequent cupping and drawing operations, since the grain structure of the wall of the ensuing cup extends in the same direction as in the cup bottom which is formed from the bulged central portions 3| and 32 of the blank.

As noted hereinabove, before the disk 30 is subjected to further working, it is annealed so as to compensate for the hardness resulting from the cold working. This practice of annealing ginal edge 34 of the blank 38, the bevel of the cup 36 gradually disappears, until in the incompletely formed casing of Figure 10 the rim has a more or less level annular top surface.

After the final drawing operation, the article 4| is cut off along the line 42, as shown in Figure 10, so as to eliminate the rough end of the casing and so as to provide a casing of exactly the desired length.

Subsequent fabricating operations as evidenced by the changes efiected in the article as shown in Figures 11, 12 and 13 are conventional operations in that they involve operations now a part of Government specifications. According to one of these operations, the article 4|, as shown in Figure 11, is flattened or upset at its bottom as designated at 43 and is indented at 44 and 45. These operations result in a formation of a flange 46 on the bottom of the casing. In the next operation, the wall of the casing is tapered as shown at 41 in Figure 12. In the flnal operations, the extreme outer end of the casing is beveled to a further extent as designated at 48 and is straightened out at 49. Also, the flattened end of the casing is tapped at 58 to form the primer hole. In addition, the closed end of the casing is grooved at 5| so as to give the flange 46 its final specified shape.

From the foregoing, it is clear that the coining operation provides and assures an adequate amount of material for the head or closed end of the cartridge. This is a very important feature in this type of casing, especially since the head end must be of great strength so as to resist the tremendous forces set up upon the flring of a shell made from this casing. Not only must the head or the closed end of the casing be of proper strength, but, in addition, very close tolerances must be maintained in the wall of the casing. Unless this is done, the shell when fired from such a casing might break off part of the casing and result in the jamming of the gun which might very easily result in the death of Or serious injury to the men manning the gun.

My invention also makes it possible to use thinner blanks to begin with than heretofore, although all the blanks will be somewhat wider.

In addition the coining operation provides a disk with thinner margins and a thickened center whereby it is feasible to Obtain on the cupping operation a deeper draw than before. This is possible since the marginal portion of the coined blank being drawn into the wall of the ensuing cup has already been thinned out before it is put into the cupping die.

I claim as my invention:

1. In a process of drawing a metallic casing, the steps of cutting a polygonal-shaped blank from a flat slab of metal, coining and squeezing a circular portion of said blank to flow the metal radially inward and form a star-shaped blank having a round center with a thickened middle portion and relatively thinner marginal portions from which project radially pointed portions separated from said margins by grooves, trimming off flash portions from the marginal portions of the round center, to form a round blank thickened at its middle, and thereafter cupping the blank with the bulged, thickened portion formed into the bottom of the ensuing cup and the thin portion into the wall of the cup.

2. In a process of drawing a metallic cartridge casing, the steps of contiguously cutting a plurality of polygonal-shaped blanks from a flat slab of metal, coining and squeezing circular metal portions inscribed within said polygonal blanks to flow the metal radially inward and form starshaped blanks having a round center with a thickened middle portion and relatively thin marginal portions from which project pointed portions derived from the-non-inscribed portions of said polygonal blanks, trimming off said projecting pointed portions and flash from the margins of the round center, and thereafter cupping the blank with the bulged thickened portion formed into the bottom of the ensuing cup and the thin margin into the walls of the cup.

8. In a process of fabricating a plurality of metallic cartridge casings from a single metal slab, the steps comprising shearing from said slab a plurality of strips each capable of being sheared transversely to form a. plurality of polygonal blanks, shearing said strips transversely to form a plurality of polygonal blanks, coining and squeezing each blank to form a round disk having a thickened middle and a thinned margin from which project radially pointed portions derived from edge and corner parts of the polygonal blanks, trimming off said projecting portions and flash from said disk, cupping said disk left by said trimming, and drawing out the walls of the ensuing cup.

4. In a process of drawing a metallic cartridge casing, the steps of cutting apolygonalshaped blank from a fiat sheet of metal, positioning the fiat blank between cooperable, aligned die members encompassing all but the corner portions of said blank, pressing said blank between said die members to flow the encompassed metal radially inward and form the encompassed metal into a circular disk having a thickened middle and relatively thinner margins, trimming oil the non-encompassed metal, and thereafter cupping the blank with the bulged thickened portion serving as a centering means for the cupping die,

this thickened portion being formed into the bottom of the ensuing cup while the thinner margins form the cup walls.

5. In a process of drawing a metallic cartridge casing, the steps of cutting a polygonal-shaped blank from a fiat slab of metal, interposing said blank between circular cooperable coining die members in concentric relation thereto with edge and corner portions of the blank protruding from between the die members, coining and squeezing said blank to flow metal from the margins thereof radially to the middle thereof and thus thicken the center portion as well as thin and bevel the margins of the blank progressively from the middle outwardly, thereafter trimming all metal protruding from between the die members, and thereafter cupping the blank with the bulged, thickened portion forming the bottom of the cup and the thinned marginal portions the wall of the cup.

6. In a process of drawing a metallic cartridge casing, the steps of contiguously cutting polyganal-shaped blanks from a flat slab of metal, coining and squeezing circular middle portions of the resulting blanks including all but edges and corners of the blanks so that the blanks are formed into star-shaped blanks having a round middle portion thickened centrally and thinned marginally, as compared with said slab, the points of said star-shaped blanks being derived from edges and corners of said polygonal blanks, then trimming off said points to leave a button having a thickened middle portion, cupping said button with the thickened middle portion formed into the bottom of the ensuing cup and the thinned margins formed into the cup walls, and then progressively drawing and reducing the thickness of the cup wall to extend the same into the desired length of cartridge casing wall.

7. In a process of drawing metallic cartridge casings, the steps of cutting polygonal-shaped blanks from a fiat slab of metal, positioning the resulting fiat blanks between cooperable aligned rounded die members with the corners of said flat blanks projecting from between the die members so as to leave between the die members circular blank areas of the maximum extent possible in view of the size and shape of said polygonal-shaped blanks, pressing said circular blank areas between said die members to form said areas into centrally thickened and marginally thinned buttons, trimming off metal not encompassed by said die members, and thereafter cupping the trimmed-off blanks.

8. In a process of drawing a metallic cartridge casing, the steps comprising shearing a flat slab of metal to subdivide the same into a plurality of blanks having straight edges and each containing enough metal to make up a cartridge casing, coining said blanks to outline thereon round centrally thickened and marginally thinned buttons, said straight edges forming tangents to the rounded figure which will ultimately outline said buttons, trimming said coined blanks to remove metal outside said outlines, and cupping the resulting round blanks to form cups having buttoms formed by the thickened centers of the blanks and walls formed by the thinner margins of the blanks.

9. In a process of fabricating a plurality of metallic cartridge casings from a single metal slab, the steps comprising shearing from said slab a plurality of strips each capable of being sheared rived from edge and corner parts of the hexagtransversely to form a plurality of hexagonal onal blanks, trimming of! said projecting portions blanks, shearing said strips transversely to form and flash from said disk, cupping said disk left a plurality of hexagonal blanks, coining and by said trimming, and drawing out the walls of squeezing each blank to form a. round disk hav- 5 the ensuing cup. ing a thickened middle and a thinned margin from which project radially pointed portions de- GEORGE ALBERT LYON.