GB1154323A - Improvements in and relating to Spot-Welding Electrodes - Google Patents

Abstract

1,154,323. Making welding electrodes; welding by pressure; extruding. JOHNSON MATTREY & CO. Ltd. 22 Aug., 1966 [24 Aug., 1965; 18 Jan., 1966],Nos. 36291/65 and 2261/66. Headings B3A, B3P and B3R. A spot welding electrode includes a reinforcing member or members extending as an insert of continuous annular shape into the electrode, the member or members being formed of conductive material of greater strength and resistance to deformation than the electrode material. A copper-chromium electrode has force fitted therein a hollow cylindrical reinforcing insert 2, Fig. 1, of sintered tungsten particles impregnated with copper and such an electrode may be made by locating a billet of the copperchromium alloy, in the end of which has been force-fitted an insert, in the cylindrical chamber of a vertical back-extrusion press and driving a plunger into the billet to deform it and form the cavity 1A. The electrode is then machined. Instead of forming the cavity by back extrusion it may be drilled. The insert may be of tungsten, molybdenum, alloys of either or both of these or sintered tungsten and/or molybdenum particles. Modified inserts comprise a number of circular, arcuate or rectangular rods arranged on a circle and touching each other. The tube formed may taper. In a further modification a billet from which the electrode body is to be formed has a central projection and an annular recess about the projection to receive a tubular insert which is secured by swaging or peening the central projection and then machining the billet. The insert may have its inner periphery cut away at the working end or it may have a tapered bore. A silver or silver base alloy washer may be placed at the bototm of the recess to improve conduction or the surfaces of the insert and recess may be silver or silver base alloy coated.