GB561448A - Improvements in or relating to methods of making explosive projectile shells - Google Patents

Abstract

561,448. Making projectiles. NATIONAL SUPPLY-CO. Feb. 2, 1943, No. 1702. Convention date, April 25, 1942. [Classes 83 (ii) and 83 (iv)] Billet-piercing ; altering physical structure.- In making projectile shells the steel billet is forged to form a blank having a cavity materially larger in diameter than that of the finished shell. The dotted line 6 shows the final shape required and a polished mandrel 8 of this size is inserted after rough machining the blank to form the centering projection 7 and to reduce the wall thickness beyond the line 5 so that the end of the blank may subsequently be cold nosed. The blank is cold reduced in diameter,. preferably by lateral swaging but cupping through a die may be employed. In the case of plain carbon steel having from 0.3 to 0. 4 per cent carbon; 0.75 to 1.05 per cent manganese ; up to 0.045 per cent each of phosphorus and sulphur; and up to 0.35 per cent silicon ; if the cavity is 3 per cent larger than the finished size cold working will increase the transverse compression yield strength,from 40,000-60,000 to 55,000-75,000 pounds per square inch. With a cavity 5 per cent larger the strength may rise to 85,000. Alloy steels such as one containing 1.5 per cent manganese give materially higher figures. The swaging may be effected by a die such as is described in U.S.A. Specification 2,178,141. The shell is finished in the usual way, but machining of the cavity wall is avoided.