GB978507A - Improvements in or relating to apparatus for electric welding - Google Patents

Abstract

978,507. Welding by pressure. M. DORMON. April 12, 1961 [April 12, 1960; Jan. 31, 1961], No. 13160/61. Heading B3R. A resistance welding machine comprises two electrodes and an electrically conductive backing unit including a pair of electrically interconnected arms each having a backing element to co-operate with a separate one of the electrodes, each backing element being offset relatively to the longitudinal axis of its arm and both elements being symmetrical about an axis common to both arms. A machine for spot welding the flanges on sides 2, Fig. 1, of a ventilation shaft to the flat faces 1 thereof comprises two liquid cooled copper alloy arms 6, Fig. 1, adjustable vertically on a frame 13 and connected by a conductive cross-member 20 which may be connected thereto as shown or integral therewith. The arms carry offset contact studs 21 associated respectively with electrodes 3, 4 which may be on a displaceable carriage. In operation the shaft, with the flanges arranged on the inside, is placed first on one arm 6 and spot welds are made along one seam by electrode 3 with electrode 4 merely in contact with the stud on the other arm 6. Then the shaft is placed on the other arm 6 and the other seam welded. The shaft may be curved and a shim may be placed between the auxiliary electrode and its backing element. The spot welding electrode may be replaced by roller electrodes and the arms 6 may be curved for use with curved shafts. The arm 6 may be of beryllium-cobalt-copper alloy or of copper portions 6, Fig. 2, supported on steel portions 6. Each arm 6 may be partly covered in insulating plastic material 26.