GB727142A - Improvements in and relating to the pressure butt-welding of metal articles - Google Patents

Abstract

727,142. Transformer systems; welding supply systems. DEUTSCHE EDELSTAHLWERKE AKT.-GES., and WUPPERMANN GES., T. Jan. 7, 1952 [Jan. 11, 1951], No. 467/52. Class 38 (4). [Also in Group XXII] In pressure butt welding metal articles, the articles are preheated by an inductor fed by higher frequency current and are then welded when current of lower frequency is passed directly through them, the currents of both frequencies being supplied by a single common transformer. In an embodiment, two articles, e.g. rods, tubes or rails, are preheated by an inductor 26. The inductor and clamps 10, 10<SP>1</SP> connected in parallel are supplied from a transformer secondary 25. Current at 2000 cycles/ sec. single phase is supplied, from one of two generators rigidly connected together and driven by a common motor, to the primary 23 for preheating and current at 50 cycles/sec. three phase is supplied from the other generator to the primary for welding, a change-over switch 20<SP>1</SP> is first moved to the right to energize a relay 22 from a 220 volt source to close its switch contacts and supply the higher frequency current to the primary when preheating is complete the inductor is hinged out from between the articles, the switch 20<SP>1</SP> is moved to the left to energize relay 27 and close its contacts so that low-frequency current is fed to the primary, the articles then being brought together for welding. The high and low frequencies may be 100-20,000 cycles/sec. and 5-50 cycles/sec.