GB1276421A - Electric welding units - Google Patents

Abstract

1276421 Resistance welding B HUMBLOT 12 March 1970 [22 May 1969] 11989/70 Heading H5H In a resistance welding unit comprising a pair of electrodes 1, 2 connected to the secondary winding of a transformer having a primary winding(s) 32, 33 on a magnetic circuit 11, the welding electrodes 1, 2 are rigidly connected to the ends of respective parallel rods 5, 6 electrically interconnected at their other ends and mounted directly in the magnetic circuit 11 so that in use the rods 5, 6 and workpiece engaged thereby form the secondary circuit of the transformer, the rods 5, 6 being movable relative to the primary winding(s) 32, 33 and to each other. The magnetic circuit 11 comprises a stack of groups of plates insulated from one another by plates 26 and from upper and lower cheeks 13, 12 by plates 29, 28. The rods 5, 6 are interconnected at their upper ends by a stack of U- shaped flexible copper laminations. Two double acting rams, e.g. 47 control the rods 5, 6 independently. As shown, the cylinder of pneumatic ram 47 is fixed to cheek 13 and the pistonrod 54, 55 is secured to a driving plate 57 in which rod 5 is secured. The rods 5 and 6 are each hollow and provided internally with longitudinal tubes, e.g. 65 which terminate near electrodes 1, 2. Water is supplied to cool the electrodes from an orifice 67 in a cap 16 through a bellows like connection 66 to inner tube 65, returns up the outside of tube 65, passes via a flexible pipe 68 to the inner tube of the rod 6 and emerges from the rod via a bellows type connection to an outlet orifice in the cap 16. In use the workpiece rests on counter electrodes. A plurality of units of the type described can be installed in a multi-spot welding machine.