US2698268A

US2698268A - Method of making shell casings

Info

Publication number: US2698268A
Application number: US179971A
Authority: US
Inventors: Lyon George Albert
Original assignee: Individual
Current assignee: Individual
Priority date: 1950-08-17
Filing date: 1950-08-17
Publication date: 1954-12-28
Anticipated expiration: 1971-12-28

Description

Dec. 28, 1954 G. A. LYON METHOD OF MAKING SHELL CASINGS 2 Sheets-Shoat 1 Fig.2

H f zz E11 far GEbeaEA LaEErLm/V Filed Aug. 17, 1950 Dec. 28, 1954 G. A. LYON METHOD OF MAKING SHELL CASINGS 2 Sheets-Sheet 2 Filed Aug. 17, 1950 Fig.

United States Patent 'Ofiice This invention relates to a method or makin shell casings and more particularly to a n'rethod of coining and drawing a metallic casing from a blank of metal cut from a sla b.

In the inanu'f'actu ife of cartridge shell casings such, "for eX'a-rnple, as are used in modern anti-aircraft and anti-tank shells, n is particularly desirable to have the metal "in the cylindrical wall of the casing hardened immediately adjacent the basewithoutha'rderfingof the base.

It is my understanding that in some of the present -methods now used, and particularly where electric anneal- 'ing is employed between the progressive drawing oper 'a'tions, soft spots tend to develop adjacent the junction of the easing wall and the base. Needless to say, any weakening of the wall at this area constitutes a source of danger in the firing of the shell "made from such a casing 'a's it would have a tendency to explode at such weakened or breach area. r p V The problem is somewhat further complicated by the fact that while thecylindrical wall must be properly hardened, the cylindrical base, on the other hand, if hardened to the ame extent, b'e'c'o'rnes 'diflicul-t re machin'e in the ultimate shaping of the base. Now I pro'posejin accordance with the features of this invention, to provide a method of making a shell casing wherein the metal is properly distributed between the base and the cylindri al wall and wherein proper hardening of the wall 'a 'be obtained without requiring that the base portion be hardened to the same extent at the s'ame tirne. i It is also an bjectof this invention to provide an improved, simplified and less expensive method of making such ine'ta'l cylindrical casings.

accordance with the general features of this invention there is provided in a lprocess of drawing a metallic cartridge casing from a blank blank into substantially a circular disc haying a thickened center portion or button with an annular marginal .port'ion tapered away from the center toward the periphery of thj disc, drawing "and clipping the disc to form a cup with the thickened center substantiall at 'the base, and

the tapering portion in the cylindrical Wall of the cup, progressively drawing 'the wall of the cup to elongate the same with a thickened wall portion ad a'cent and merging fint'o the base (if the cu bulging said thickened -wall;portion radially outwardly and progressively drawing said 'hiilg'e'd portion away from the base lengthwise into the wall'to cold work the same. 7

Another feature of the invention relates to the contemporaneous cupping and drawing =of the coined blank so as toeliminate the necessityofaseparate drawing step.

Yet another feature of the invention relates to :sub- :jecting the lower 'partof the casing, after the bulging and cold working =of the lower lpertion of the wall to a salt bath heating treatment for preserving the desirable cold workingcharacteristics obtained in the bulging and work- -ing of such lowertportioir of thecasing'wall.

Other object'sa'nd f'eatures of this invention 'will more frilly appear from the followingdetailed description taken in connection with the accompanying drawings which illustrate the steps of my process andwherein:

Figure 1 is a planview of'a polygonal or s'quareshaped blank;

Figure 2 is an "end or "edge view of a blankshown 'in Figure 1;

, Tth e steps of coining the 7 2,693,268 Patented Dec. 28, 1954 Figure 3 is a cross-sectional view through a disc coined from the blank in accordance with my process;

Figure 4 is a fragmentary cross-sectional view showing diagrammatic die numbers and a punch in the process of cupping and drawing the coined disc;

Figure 5 'is a fragmentary vertical cross-sectional view through a cylindrical cup formed from the initial cupping or drawing steps";

Figures 6 and 7 are vertical cross-sectional views through the cylindrical casing progressively drawn from the cup shown in Figure 5 and showing how the bottom wall of the casing is thickened and tapered into the base of the casing;

Figure 8 is an enlarged fragmentary cross-sectional view of a lower portion of the casing shown in Figure 7 and 'illustrating'by dotted lines the lower tapered thickened portion which is to be bulged radially outwardly;

Figure 9 is a fragmentary cross-sectional view similar to Figure 8 showing how the tapered thickened portion 'is bulged outwardly after being subjected to a punch or press operation and illustrating in dotted lines the position of the thickened portion prior to the bulging operation;

Figure 10 is a fragmentary vertical cross-sectional view through the casing showing how it looks after the bulged portion has been uniformly drawn into the cylindrical wall of the casing as well as showing the base perforated; and

Figure 11 is a vertical sectional view through the casing after the base has been shaped to form a flange thereon.

As shown on the drawings:

It is believed "that my novel process'will be fully understood from a description of the foregoing drawings showing diagrammatically the condition of the blank, cup and casing at difier'ent stages of the process of fabrication.

While it is contemplated that my invention may be employed in the fabrication of cartridge casings, such as '40 mm. casings shown "inrny issued Patent No. 2,860,354, my "invention is not limited in its application to that particular size of casing. as it may be used equally well with other sizes and particularly in the fabrication of larger gau ge cartridge casings. v Also, while my invention is particularly adapted for use in the fabrication of casings from low carbon steel, it is not to be thus limited as it is c ntem lated that it could be used to advantage in the making of casinos from brass blanks. However, if the casing is made from a brass blank, it may require more annealing operations between draws than it would where the casing is made from low carbon steel.

The reference character 10 designates generally a square of ol onal sha e of metal cut or sheared from a suitable slab. Subsequent to this shearing operation, the sides of .the bl nk are suitablyround .to eliminate bumps and irregularities. Also, the blank can be subiected .to suitable annealing such, for example, as a so-called spheroidizinn anneal.

Th re fter. the blank is placed onto a suitable coining die whi h may be enerally similar to that shown .in my f resaid p ent and coi ed into a circular disc of predetermined diameter c nsistent with the particular size of easin b ing made. During this coiningoneration, the c ined disc 11 (Figure .3) is provided with a central thicke ed portion r button '12 and an annularmarainal inclined. portion 13 which tapers from the center 12 to the peripher of the-disc. A suitable trimming'operation is employed for trimmin off theexcess metal or flash .be d he ed e-of he'coined disc lil.

Subsequent to this coining o eration the coined disc may be suitably annealed by subiecting it to a bonderizing anneal or the like. It is to be understood in the description of the'subsequent operations that, if required, the :article maybe subjected to annealing and pickling throughout the different steps or.stages of the process. .It is, of course, well knownin the metallurgy art that an article, as it is progressively worked or drawn, may require annealing between operations in order :to vcondition the .metal.

:In Figure 4 -I have illustrated diagrammatically the next -step .of .the process which combines cupping and drawing in a single operation. In this operation the coined disc 11 is placed between suitable cooperating die members 14 and 15 and upon being subjected to the action of the punch 16 is caused to be cupped. In th s cupping operation the central thickened portion 12 is pushed downwardly in the die members. At the same time the tapered portion 13 is pulled downwardly through the dies causing it to be elongated. In this action of drawing the portion 13 is first pulled between the die members which results in the wiping and working of the metal. Continued movement of the punch 16 downwardly results in the pulling of the entire tapered portion about the punch, thereby resulting in the formlng of a cupped case 17 (Figure having a thickened base 18 and a cylindrical wall 19 which is of a lesser thickness than that of the initial tapered portion 13.

Following this initial cupping and drawing operation, the casing is subjected progressively to additional drawing operations to progressively reduce its wall 19, as shown in Figures 6 and 7, and to provide at the jlll'lCtlOH of this wall at the base 18 a tapered thickened section or portion 20 which is best shown in Figure 8.

I propose. in accordance with the features of my process, to use this ta ered thickened portion 20 for the purpose of augmenting the hardness of the metal in the casing wall immediately above the base 18 without substantially affecting the hardness of the base itself.

It will be appreciated that in forming this tapered thickened portion 20 a punch with a tapered end is employed.

Now I propose to push or bulge this thickened portion 20 radially outwardly from the full line position shown in Figure 8 to the dotted line position. I effect this by using a punch with a straight cylindrical wall at its end which, u on entering the c sing, progressively bulges the portion 20 from the dotted line position shown in Figure 9 to the full line position. This results in a cold w rking of the wall at this thickened portion 20 without affecting the other portions of the casing. n other words, the portion 20 is sub ected to more cold working than the up er part of wall 19 and base 18.

Subsequent to this bulging operation. the drawn cylindrical casing, as shown in Fi ure 10, is sub ected to additional drawing operation hich progressively moves the metal of the bulge 20 uniformly u ward distributing it in the cylindrical wall 19 so that the wall. with the exception of its base 18, is then of substantial uniform thickness.

At some time in the various drawing operations, a hole 21 is punched in the base 18. Then. as sho n in Figure 11, the base 18 is shaped to provide it with a flange 22.

In order to preserve the cold working characteristics of the metal immediately above the base 18, derived during the workin of the bulge 20. I propose to subiect the lower part of the casing to a heat annealin process such as that shown in my issued Patent No. 2,059. 68. In this heat treatment the lo er end of the casing is inserted in a ba h of fused salts at a temperature of from about l450 F. to 165m F. for a very short period of time. less than five minutes, and thereafter such heat treated end is ouenched in a bath containing a sa t of one of the alkali metals and lime. n other words, I heat the casing at the area immediately above the base rapidly to a t mperature in the vicinity of the AC3 point in a non-oYidizing heat medium for a sufiiciently short period of time so as not to chan e the characteristics of the steel obt ined durin the cold workin operation. Quickly thereafter I quench the steel to harden it at portion 20.

It will be appreciated that by reason of the base 18 being substantially thic er th n the ad ining wall por- 4 tion. the adioining wall portion will heat up rapid y so that by ro er timing very little heat need be imparted to the base portion 18. That is to say. I am desirous of avoidin undue h rdness of the b se 18 since it is easier to machine when it is not unduly hardened. Moreover, it does not require the hardness that is necessary at its iunction portion with the cylindrical wall.

During this heat treatment operation, the salt solution can readily enter the lower part of the casing through the hole 21 which likewise is employed for draining the casing when it is removed from the heat treatment bath. In the event the casing is made from brass instead of low carbon steel, I contemplate using the cold working obtained by the portion 20, although in that event the casing would not be subjected to the salt bath heat treatment noted above. From the standpoint of the actual cold working of the metal, it may be found that other processes of heat treating could be used equally as well as my own referred to above and described more in detail in my aforesaid Patent No. 2,059,468.

' From the foregoing description it is evident that the augmented thickness of metal above the portion 20 may be completely distributed in the wall of the casing without any overlap of the metal and all without disturbing the base proper. In addition, the work hardening of the wall immediately above the base will eliminate dead spots at this area, such as heretofore existed in casings where electronic heating has been employed in the annealing of the metal.

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

1 claim as my invention:

1. In a process of drawing a metallic cartridge casing from a blank, the steps of coining the blank into a substantially circular disc having a thickened center with an annular marginal portion tapering away from the center toward the periphery of the disc, drawing and cupping the disc to form a cup with the thickened center substantially at the base and the tapered portion in the cylindrical wall of the cup, progressively drawing the wall of the cup to elongate the same with a thickened wall portion adjacent and merging into the base of the cup, bulging said thickened wall portion radially outwardly, and progressively drawing the material of the outer surface of said bulged portion away from the base into the wall to cold work the wall immediately above the cup base.

2. In a process of drawing a steel cartridge casing from a blank, the steps of coining the blank into a substantially circular disc having a thickened center with an annular marginal portion tapering away from the center toward the periphery of the disc, drawing and cupping the disc to form a cup with the thickened center substantially at the base and the tapered portion in the cylindrical wall of the cup, progressively drawing the wall of the cup to elongate the same with a thickened wall portion adjacent and merging into the base of the cup, bulging said thickened wall portion radially out wardly, progressively drawing said bulged portion away from the base into the wall to cold work the wall immediately above the base, heating the steel in the lower portion of the wall to a temperature of about 1450 F. to 1650 F. for a short interval of time in a non-oxidizing heating medium whereby the wall immediately above the base will be heated to said temperature but the base will be heated to a lesser temperature only, and then plunging the lower part of the casing in an aqueous quenching bath whereby the hardness imparted to said casing adjacent said base portion by cold working will be preserved and said thickened base portion will remain in a semihard state only.

3. In a process of drawing a steel cartridge casing from a blank, the steps of shaping the blank into a substantially circular disc having a thickened center with an annular marginal portion tapering away from the center toward the periphery of the disc, drawing and cupping the disc to form a cup with the thickened center substantially at the base and the tapered portion in the cylindrical wall of the cup, progressively drawing the wall of the cup to elongate the same with a thickened wall portion adjacent and merging into the base of the cup, bulging said thickened wall portion radially outwardly, progressively drawing said bulged portion away from the base into the wall to cold work the wall portion immediately above the base, perforating the base, plunging the lower part of the casing including said cold worked wall portion into a heat treating bath at a temperature in the vicinity of the AC3 point for a sufiiciently short period of time so as to preserve the characteristics of the steel in the cold worked portion of the wall, thereafter removing the casing from the bath and draining the bath out of the lower part of the casing through the perforation, and quenching the casing to harden the cold worked portion of the wall.

4. In a process of drawing a cylindrical casing from a blank, the steps of forming the blank into a substantially circular disc having a thickened center, drawing and cupping the disc with the thickened portion located principally at the base of the cup, progressively drawing the wall of the cup to elongate the same with a thickened inwardly tapering portion adjacent andmerging into the base of the en bulging thickened wall portion radially outwardly to increase the internal and external diameters of the thickened wall portion and progressively drawing the bulged portion away from the base into the wall while maintaining the inner diameter of said wall portion at substantially said increased internal diam eter but substantially reducing said external diameter of said wall portion to cold work same.

5. In a process of drawing a metallic casing from a slab, the steps of forming a circular disc from the slab, drawing and cupping the disc to form a cup with a thickened center substantially at the base, progressively drawing the wall of the cup to elongate same with an inwardly tapering thickened portion adjacent and merging into the base of the cup, bulging said thickened wall portion radially outwardly to increase the internal and external diameters of the thickened wall portion, and progressively drawing said bulged portion away from the base and into the wall while maintaining the inner diameter of said wall portion at substantially said increased internal diameter but substantially reducing said external diameter of said wall portion.

6. In a process of drawing a metallic cartridge casing from a blank, the steps of coining the blank into a substantially circular disc having a thickened center portion with an annular marginal portion tapering away from the center toward the periphery of the disc, placing said disc between and subjecting the same to the action of cupping die members and thereby drawing and cupping the disc to form a cup with the thickened center portion substantially at the base and the tapered portion in the cylindrical wall of the cup, progressively drawing the wall of the cup to elongate the same with a thickened wall portion adjacent and merging into the base of the cup, bulging said thickened wall portion radially outwardly, and progressively drawing said bulged portion away from the base into the wall to cold work the wall immediately above the base.

7. In a process of drawing a metallic cartridge casing from a blank, the steps of coining the blank into a substantially circular disc having a thickened center portion with an annular marginal portion tapering away from the center toward the periphery of the disc, placing said disc between and subjecting the same to the action of cupping die members and thereby drawing the disc to form a cup with the thickened center portion substantially at the base and the tapered portion in the cylindrical wall of the cup, of the cup to elongate the same with a thickened wall progressively drawing the wall portion adjacent and merging into the base of the cup, bulging said thickened wall portion radially outwardly, progressively drawing said bulged portion away from the base into the wall to cold work the wall immediately above the base, and heat treating the cold worked portion of the casing in a fused salt bath to condition same without materially hardening said base portion.

8. In a process of drawing a metallic cartridge casing from a blank, the steps of coining the blank into a substantially circular disc having a thickened center portion with an annular marginal portion tapering away from the center toward the periphery of the disc, placing said disc between and subjecting the same to the action of cupping die members and thereby drawing the disc to form a cup with the thickened center portion substantially at the base and the tapered portion in the cylindrical wall of the cup, progressively drawing the wall of the cup to elongate the same with a thickened wall portion adjacent and merging into the base of the cup, bulging said thickened portion outwardly and working said bulge upwardly into the wall to cold work the wall adjacent the base and heat treating the work hardened portion of the casing in a fused salt bath to condition such portion above the casing base.

In a process of drawing a cylindrical casing from a metal blank, the steps of coining and cupping the blank to form a cup having a cylindrical side wall and a comparatively thicker base, progressively drawing the wall of the cup to elongate the same with its thickest wall portion adjacent and merging into said base, bulging said thickest wall portion radially outwardly and progressively drawing said bulged portion away from the base igtoghe cup wall to cold work the wall immediately above t e ase.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,296,842 Ofiut et al. Mar. 11, 1919 1,526,894 Bellis Feb. 17, 1925 2,059,468 Lyon Nov. 3, 1936 2,360,353 Lyon Oct. 17, 1944 2,360,354 Lyon Oct. 17, 1944 2,402,068 Meador June 11, 1946 FOREIGN PATENTS Number Country Date 819,880 France July 19, 1937 561,448 Great Britain May 19, 1944 858,740 France Dec. 2, 1950

Claims

3. IN A PROCESS OF DRAWING A STEEL CARTRIDGE CASING FROM A BLANK, THE STEPS OF SHAPING THE BLANK INTO A SUBSTANTIALLY CIRCULAR DISC HAVING A THICKENED CENTER WITH AN ANNULAR MARGINAL PORTION TAPERING AWAYS FROM THE CENTER TOWARD THE PERIPHERY OF THE DISC, DRAWING AND CUPPING THE DISC TO FROM A CUP WITH THICKENED CENTER SUBSTANTIALLY AT THE BASE AND THE TAPERED PORTION IN THE CYLINDRICAL WALL OF THE CUP, PROGRESSIVELY DRAWING THE WALL OF THE CUP TO ELONGATE THE SAME WITH A THICKENED WALL PORTION ADJACENT AND MERGING INTO THE BASE OF THE CUP, BULDGING SAID THICKENED WALL PORTON RADIALLY OUTWARDLY PROGRESSIVELY DRAWING SAID BULGED PORTION AWAY FROM THE BASE THE WALL TO COLD WORK THE WALL PORTION IMMEDIATELY ABOVE THE BASE, PERFORATION THE BASE, PLUNGING THE LOWER PART OF THE CASING INCLUDING SAID COLD WORKED WALL PORTION INTO A HEAT TREATING BATH AT A TEMPERATURE IN THE VICINITY OF THE AC3 POINT FOR A SUFFICIENTLY