Improved method and apparatus for the manufacture of cylindrical metallic shells

摘要

684,735. Sand-blast. GENERAL MOTORS CORPORATION. March 5, 1951 [March 23, 1950], No. 5206/51. Drawings to Specification. Class 60. [Also in Group XXII] An extrusion die (see Group XXII) is of tungsten carbide which is ground and lapped to a high polish and then sand-blasted to remove the appearance of polish in order that the working surfaces may retain lubricant.