GB1256972A - - Google Patents

Abstract

1,256,972. Winding resistances. ELECTRONIC ASSOCIATES Ltd. 6 Feb., 1969 [30 Jan., 1968; 27 Aug., 1968], Nos. 5973/69 and 40871/68. Heading B3A. In a method of winding a resistance wire on an insulated mandrel to form a potentiometer winding, the insulating material is softened by passing an electric current through the wire so that the wire partly embeds itself in the insulating material and the turns of wire are thereby held in spaced apart positions. The mandrel, which may be an enamel insulated copper wire 1 coated with PVB, is rotated between chucks (not shown) and passed through a hollow guide nose 2, which guides resistance wire 3 into coils 4 of the required pitch. The wire is fed from a package 5 via a tensioning capstan 8 and electric motors 6, 9 are energized to rotate oppositely to the feed direction to tension the wire 3. The capstan 8 is partly immersed in a bath of cleaning solvent to clean the wire. A gold alloy brush 11 moves along the wire together with the nose 2 and the assembly of the package 5, pulleys and motors in the direction of the arrow. Electric current is supplied to the wire 3 between the brush 11 and the capstan 8 from a supply 12, thereby sufficiently heating the wire to soften the PVB around the core wire 1, and the current passed therethrough will depend upon the depth of penetration required into the insulation. The wound core wires, when removed from the chucks may be subsequently wound into helices. The spacing between adjacent turns of the resistance wire may be about one quarter of its diameter.