GB563360A - Improvements in and relating to a method of and apparatus for making wire-drawing dies - Google Patents

Abstract

563,360. Abrading. BRITISH THOMSON-HOUSTON CO., Ltd. Feb. 4, 1943, No. 1848. Convention date, Feb. 6, 1942. [Class 60] [Also in Group XXXVI] The drawing-apertures of wire-drawing die nibs of electrically-conducting sintered material, such as tungsten carbide cemented with cobalt, are formed or shaped by a. combined anodic electrolytic and mechanical abrasive treatment in which a supply of electrolyte containing particles of abrasive material, such as silicon carbide, is maintained between the nib and a reciprocating and rotating cathode needle. The electrolyte is preferably a concentrated solution of sodium carbonate or similar alkali. As shown, the electrolyte containing abrasive particles 77 is circulated by a pump 46 and directed through a nozzle 49 between the needle 30 and the nib 14. The needle .30 is rotated by a belt 66 from a motor driven shaft 42 and is reciprocated by a cam 64 driven by a belt 63, a spring 65 preferably acting on the cam follower 61 to assist the downward movement. The contact member 55 is vertically adjustable on the support 56 for controlling the current. The tank 10 can be raised by means of a hand wheel 38 to bring the nib into' position relatively to the needle, a nut 38<1> providing a fine adjustment for the latter. The needle can be lifted and lowered through a rack and pinion 67, 68 from a hand lever 69. In a modified apparatus, Figs. 6 and 7 (not shown), for shaping the end of a drawing hole, the nib is not submerged in the electrolyte. Specification 335,003, [Class 41], is referred to.