GB571228A - Improvements in or relating to electrical contacts - Google Patents

Abstract

571,228. Making electric contacts. IGRANIC ELECTRIC CO., Ltd. Nov. 11, 1943, No. 18768. Convention date, Nov. 12, 1942. [Classes 83 (ii) and 83 (iv)] [Also in Groups II, XXXVI and XXXVII] Electric contact members are moulded from powdered metal with the incorporation at one face of a piece of gauze or expanded metal to serve as reinforcement and to facilitate electric welding or brazing to a support. A lower die formed by parts 21, 22, Fig. 14, has a plate 23 above of such thickness that the powdered metal is filled into the die level with the top surface of the plate. A corresponding plate 24 is separated from the plate 23, on the upstroke of the press, by springs 26 to permit the feeding of a strip of wire gauze between the plates. On the downstroke the punch 25 shears a blank from the strip and consolidates the powder, forcing it into the meshes and wholly or partly round the wires as at 20c, Fig. 5. The contact is moulded with a,convex upper surface and may be of elongated or circular &c. form. It may be given a number of projections 28c, Figs. 7 and 8, on the reinforced side further to facilitate welding &c. by reducing the initial contact area. The dies of the press are electrically heated at x, y in known manner. The moulding pressure is about 40,000 lbs. at a temperature of 400‹ F. The reinforcement may be preformed and may be placed in the die below the powder. The powder may be, in parts by weight, precipitated silver 67, crystalline silver of 80 mesh or finer 22, and cadmium sulphide 11, as described in U.S.A. Specification 2,288,122. The wires of the gauze are of bronze, brass, copper, steel or stainless steel, &c.