GB897015A - Improvements in methods of cold extrusion of metals - Google Patents

Abstract

897,015. Extruding. SOC. F. MARTI & FILS. Sept. 28, 1959 [Oct. 6, 1958; Dec. 11, 1958], No. 32852/59, Class 83 (4). A method of coldextruding a metal workpiece, particularly of alloy steel, comprises forming a depression 6 in the top of the workpiece la, Fig. 2, depositing a solid lubricant in the depression, and then piercing completely through the workpiece and separating therefrom the web of material 6 driven forwardly by the piercing punch 4. A cylindrical, oval or polygonal section blank provided with a phosphate coating, is placed in a die 2, 3 and indented by the punch 4. The indent 6 is filled with a solid lubricant, particularly molybdenum or tungsten bisulphide, and is pierced partially through with backward extrusion, Fig. 3 (not shown). An ejecter 5 actuated by a member 5a is provided. Die 2 is then placed upon another bottom die 3a, Fig. 4, and the punch 4 is forced completely through the workpiece to sever off a wad 6 at the throat 10. After removing any burrs by reaming, followed possibly by a preliminary heat treatment for several hours at 300-400‹ C. and then immersing in the solid lubricant, the workpiece le is inserted, in a reversed position, in an extrusion die 17, Fig. 6, another workpiece 1d is placed on top to act as a block, and the workpiece le is cold extruded by a ram 12 carrying a mandrel 13 to form a tube 1# which may be used subsequently as a gudgeon-pin. An undercut groove 18 prevents the workpiece being raised with the mandrel. In a modification, Fig. 10, the ram 10 is recessed at 22 to form an annular groove 19 in the workpiece for receiving the solid lubricant. The latter may be suspended in a lubricating soap. A press having a revolving work-table may be used for performing the various steps.