GB1504761A - Method and apparatus for resistance welding electrically-conducting tubular and flat parts together - Google Patents

Abstract

1504761 Resistance welding SOC ANON DES USINES CHAUSSON 13 March 1975 [20 March 1974] 10616/75 Heading B3R A method of resistance welding a tube 2 to a plate 1, e.g. a heat exchanger tube to a header box, so that an aperture 3 in the plate communicates with the inside of the tube, comprises the steps of placing one end of the tube 2 either around the aperture or into said aperture to form an electrical connection 7 between contacting portions thereof, inserting a first electrode 5 having a tapered head into the end of the tube to engage an oblique face 5a with the peripheral edge of the tube or aperture, placing a second electrode 4 either on the plate or tube in a location to provide an electric current path through the said contacting portions, passing an electric current between the electrodes 4, 5 to form a resistance weld, and being characterized in that at least one of the electrodes, e.g. the electrode 5, is movable so that the oblique wall 5a increases the pressure at the weld joint, the movement of the electrode being limited to a small distance by movement limiting means D so that initially the pressure ensures current flow to make the weld, but thereafter current flow drops. The end of the tube, or the edge of the aperture, may be roughened to increase the electrical resistance at the contacting portions. The second electrode 4 may grip the tube so that movement of the electrode moves the tube on to the tapered head of the electrode 5. The tapered head may include a ceramic centring piece 6. A flux may be used.