Resistance welding clad sheet or pipe - esp. mfg. aluminium-clad pipe, where welding wire is fed into V-gap during welding

摘要

Resistance welding process for joining the edges of metal sheet, the novelty being that a V-shaped gap is formed between the edges, the V-gap extending over at least part of the sheet thickness, and a welding wire laid in the gap; the assembly is then placed between two welding electrodes so that one electrode is in contact with the welding wire whereas the other electrode is on the surface of the sheet next to the root of the gap; and during welding, the voltage drop occurs predominantly between the welding wire and the electrode with which it is contact and/or between the wire and the edges of the sheet. The process is pref. used for mfg. pipe from clad sheet. Esp. the welding of tube formed from steel strip clad on at least one surface, e.g. with Al 50 um or more thick, and where the steel strip is 0.5-2.5 mm thick. Reduced deposits of e.g. Al on the electrodes and a welding speed of 3-5 m/min. whereas in conventional welding clad strip only 0.5-2 m/min. can be obtd.