GB974050A - Method of and apparatus for making brush contact assemblies - Google Patents

Abstract

974,050. Making contact brush assemblies; angular bending dies; soldering. SMITHCORONA MARCHANT Inc. May 1, 1962 [June 19, 1961], No. 16587/62. Headings B3A, B3E and B3R. A method of making a contact brush assembly, for use in sensing perforations in a tape, having a plurality of brushes each composed of a plurality of individual wires connected electrically together and secured to spaced support members of insulating material comprises, providing a pair of spaced parallel post members having an upper metal surface, placing lengths of wire across the upper surfaces of said post members in a predetermined pattern, soldering the wires to them and the individual wires of each brush to each other whilst in said pattern to form a sub-assembly, the solder being applied a set distance along the wires toward the centre of the brush, placing said sub-assembly on a die element with the post members on opposite sides thereof, bending the wires over an edge of said die to form " V "-shaped contact portions at a central position of each wire and placing the sub-assembly on said support members. Three beryllium copper wires 23 having a diameter of 5-20 mm., which comprise a contact brush 40 are cut from a wire coil and mounted on a base 100 having a radiused face 104 equivalent to the radius of the wire coil. The base comprises two parallel slots 106 which house metallic or metal coated post members 114 retained by screws 120 and flush with the face 104 and a pair of slots 108 which house aligned aluminium guide members 110. The wires 23 are located side by side in the slots 112 of the members 110 with their ends overlaying the post members 114. Solder is applied to each end of the assemblies to solder each group of three wires together and to the post members 114 and during the operation solder is caused to run up the contact wires to the slots 112 to retain the wires together. The post members 114, and the attached soldered bush sub-assemblies are subsequently removed from the base 100 and transferred to a bending die 200. The die comprises retaining clamps 206, an inverted V- shaped central section bounded by inclined surfaces 214 and guide pillars 202 on which an upper member 204 having a complementary configuration is fitted. The sub-assembly is retained in position by clamping the post members 114 to the side of the die 20 and the sets of brushes 40 are permanently deformed between the dies to form a centrally positioned V. The contact brushes are removed and fitted into shallow grooves formed in the end surfaces 34 of the edge portions 28 of a contact carrier block 22. The grooves are approximately three diameters wide and one diameter deep and the wires are retained by a suitable non-conducting epoxy resin adhesive which also secures a coverplate 29 placed over the protruding V portions of the brushes to the assembly. Finally the metal support posts 114 are cut from the ends of brushes along the line 240 to separate each brush.