GB727670A - Improvements in or relating to the cold extrusion of steel - Google Patents

Abstract

727,670. Making cupped articles and hollow-ware. MULLINS MANUFAC. TURING CORPORATION. April 22, 1952 [April 23, 1951], No. 10072/52. Class 83 (2) and 83 (4). Forging; extruding.-In the first step of cold working a solid steel blank to form a cup-shaped or hollow article a blank 1 cut from a rolled bar is worked by a punch 12 in a die 2, Fig. 2, which laterally expands the blank and forms it with an upper tapered recess 20, a lower tapered projection 26 and tapered side and bottom walls 24, 25. The blank so formed is also accurately trued. In the second step the blank is compressed in a die 28, Fig. 3, with a series of cylindrical and tapered inner surfaces between a punch 41 and a support member 38 which also forms an ejector. The punch enters the blank so that a tapered end 49 forms a cup from the projection 26, displaced metal being rearwardly extruded between the punch and die to form a cupshaped blank 52, Fig. 11, with a secondary cup 54 projecting from the bottom. After this operation the work is annealed. The bottom of the blank is then further worked, firstly to deepen the secondary cup and to form a raised ridge 101 of metal at the junction of the secondary cup 96 and the bottom wall 98 of the primary cup 95, Fig. 12, and secondly to round the bottom of the primary cup and to further elongate the secondary cup by a slight extrusion as shown in Fig. 6. The bottom 127 of the secondary cup is next heavily compressed between the bottom of a punch and an anvil to eliminate grain-flow lines and produce granular fusion, 'thus giving a dense structure. The relatively thick upper part 122 of the wall of the blank is then elongated by direct extrusion by a punch 166 in a die 157, Fig. 8, the bottom 148 not being further worked. Gas pressure is relieved by a passage 177 through the punch. A tapered portion 169 of the punch co-operates with the extrusion orifice 162 of the die to thin the upper end 176 of the walls of the blank. The outwardly curved upper edge 174 is subsequently drawn and trimmed to form the blank shown in Fig. 14. In order to form a pressure container, Fig. 15, this edge is swaged to form a curved end 181 with a central projecting neck 182.