US1296842A - Method of making cartridge-cases. - Google Patents

Description

1. W. OFFUTT, I J. DUNN & I. H. NICHOLSON METHOD OF MAKING CARTRIDGE CASES.

Hm 9/ m m m m APPLICATION FILED D EC. 1B, I9I5.

INVENTORS QW MQIWI WITNESSES J. W. OFFUTT, .l. J. DUNN & J. H. NICHOLSON. METHOD OF MAKING CARTRIDGE- CASE$. APPLICATION FILED DEC. 18. 1915.

Patented Mar. 11. 1919 Z'SHEETS SHEET 2.

'WITN ESSES a citizen of the ED STATES P TE OFFICE.

PJ'OHN w. orru'rr AND JERRY J. iiuNN, or ELLWOOD CITY, AND JOHN H. NlcnonsoN, or

PITTSBURGH, PENNSYLVANIA.

mn'mon or MAKING cemnmon-cnsns.

To all whom it may concern:

Be it known that we, JoHN W. Orro'rr and JERRY J. DUNN, citizens of the United States, residing at Ellwood City in the county of Lawrence and State of Pennsylvania, together with JOHN I United States, residing at Pittsburgh, in the county of Allegheny and State of Pennsylvania, have invented a .new and useful Improvement in Methods of Making Cartridge-Cases, of which the followingis a full, clear, and exact description, reference being had to the accompanying: drawingsaforming part of this specification, in w'h1ch- Figure 1 shows the heated blank out from a bar, bloom or billet.

Fig.' 2 is anend elevation of the same. Fig. 3 shows the first forming step.

'Fig. 4 is a partial longitudinal sectionof 'the blank after piercing.

Fig. 5 shows the hot drawn blank, indieating in dotted lines the machining of the 'sam 'and' e v Fig. 6 shows the turned and trimmed cut blank. L

Figs. 7 and 8 show portions of the blank after-two successive cold drawing operations,

Fig. a view of the blank after the third cold drawing operation and the press ing out of the base rim'portion.

Our invention relates to the manufacture of steel cartridge cases. Heretbfore these have generally been made of brass on account of the difliculty of forming and drawing steel cases and ofv obtaining therein the necessary physical properties to when subject to ,the firing pressure. These physical properties are necessary in order 'to avoid the difliculty of extraction due to jamming of the case the breech of the splitting or permagunresulting from such nentexpansion. V 0

We have discovered a method by which,

' e of steel and subjectsteel cartridge cases quirements and provide a cheaper case than that made of brass.

In. carrying out our process, we employ a 7 class or grade of steel having a moderate amount of a hardening or toughening agent, referablycarbon. Other hardening agents maybeemployed,-but the steel mu Specification of Letters Patent.

H. NioHoLsoN,

prevent splitting or permanent expansion of the case cold-drawing of the of a grade which may be'worked in the forming operations and at the same time may be toughened or tempered by heat treatment tions for cartridge cases, and at the same time the base portion which is the part particularly requiring the elastic recovery propbe toughened and tempered at a erties may temperature'which will not destroy the Patented Mar. 11, 1919. Application filed December 18, 1915. Serial No. 67,579. r

to "enable them to resume fects-of cold drawing, but will raise the-elas-. Y

tic recovery to the desired extent.

The steel is rolled into the form of a bar or billet either round or square, or of any desirable shape, which. is heated and cut into suitable lengths, such as shown in Fig. 1. This blankis then preferably given a preliminary forging operation to furnish the blank of Fig. 3, in which a central indentation?) is formed at one-end, and a central projection 4 at the other end.. This may be carried out at the first heat, after which the blank is preferably reheated. After reheat ing, the blank is put in a suitable die and hot-pierced and shaped to formthe hollow blankof Fig. 4. This blank has the side walls 5 and thebase 6 with an endwise annular projection being inset at 8. It is then hot-drawn in a drawingmachine, preferably at the same heat, to elongate it and thin the side walls, as shown in Fig. :5. The blank is then allowed to cool and the outer portion of the cylindrical wall suitable machine, as indicated in dotted lines at 9 in Fig. 5, and the open end portion of the blank is cut 0 or trimmed, giving the blank of Fig. 6. his machining operation is ofgreat advantage preliminary to the the blank. This blank is then subjected to several cold drawing operations, preferably three in number.

Figs. Sand 8 show the blank after two of these col drawing operations and after the isturned off in a lathe or 7, the central portion third cold drawing operation the blank is.

this projecting flaiige is forced out and into the plane'of the case, including a' short portion of the side walls, preferably by heating this portion to afproper temperature and oil tempering the same. This tempering operation'toughens and increases the strength of the base portion which is otherwise liable to permanently bulge under the high pressures of firing charge. The cold drawing operations give the thin side walls of the case the requisite physical properties, but thiscold draw-v ing does not affect the base portion sufficiently to give the required strength and characteristics. Consequently, we heat-treat this lower thicker basepart,.including the juncture. with the side walls, order to secure these properties.

The case isthen also preferably coated" with a protective metal, such as'copper, and thismay be carried out by electro-platin'g, or any other desirable process, to avoid corrosioirduring storage.

The advantages of our invention will be obvious to those skilled in the art, since the process enables a cheaper case to be made while, at the. same timegthe required physical characteristics of material are provided.

' The lower side walls of the case. must be of strength of the peti ion of the case join the base and side walls. i

such a character as to contract after being reliev'edof the firing pressure. In. the firing operation the walls of the case and the'bot-- tom are. distended against the wallof the cartridge .nha-mber and breech block of the gun, and thesecase walls andbottom must then contract after the pressure is released, in order to provide for easy withdrawal of the used case.

We can obtain these desired characteristics by using a steel having a moderate amount of hardening or toughening agent;

, as we findthat the cold drawing operations, together withheat treatment thereafter, will 'impart the necessaryresilience to the lower portion of the case; as well as increase? Steel containing. other hardening ag than, carbon may b m l the g steps. may be varied, and'other, variations may be made without departing from our invention, as we consider ourselves the first to obtain a steel case having. the required strength and elastic recovery characteristics Zessential in this article.

We claim: 1. In the manufacture of steel cartridge cases, the steps consisting of hot-drawing a hollow blank, allowing the same to'cool, machining the exterior of the wall, then colddrawing the blank, and then heat-treating the base of the case to raise its co'efficient of elastic recovery, substantially as described.

7 2. In the manufacture of steel cartridge cases, the steps consisting of cold-drawing a hollow blankofahardening steel, and then heat-treating the lower portion of the blank to raise its coeflicient of elastic recovery, substantially as described.

3. In the manufacture of steel cartridge cases, the steps consisting of hot-shaping a hollow blank of a hardening steel, cutting away the exterior portion of the wall,'then subjecting the same to two or more drawing operations, and then heat-treating the base of theblank to raise itscoeflicient of elastic recovery, substantially as described.-

4. In the manufacture of steel cartridge cases, the steps consisting of hot-shaping a hollow blank from a hardening steel, hotdrawing the same, then cold-drawing the hollow blank, and then heat-treating the base of the blank to raise its coeflicient of elastic recovery, substantially as described.

5. In the manufacture of steel cartridge cases, the steps consisting of hot-forging a hollow blank from steel'containing a sufli-' cient amount of a hardening agent to provide for tempering under heat'treatment while notpreventing the hot forging there- 7 of, thereafter cold-drawing the blank, and thereafter heat-treating the. lower portion of the blank to raise its coeflicient of elastic recovery, substantially as described.

6. In the manufacture of steel cartridge cases, the steps consisting of subjecting a hollow blank containing approximately .40 carbon to a succession of cold-drawing operations, and thereafter heat-treating the lower portion of the blank to raise its coeflicient of elastic recovery, substantially as described.

In/t'estimony' whereof, we have hereunto set our hands.

. JoHNw. OFFUTT.

JERRYJ DUNN. I JOHN NICHQLSON.

' Witnesses as to John W. Ofi'utt and Jerry J. Dunn:

* G. E.Monms,

M. B; POULTONJ Witnesses as to John Nicholson: CHRIs SPRING,

P, F. HELBLING-

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