GB1314752A - Alternating-current arc-welding apparatus - Google Patents

Abstract

1314752 Welding by fusion VSESOJUZNY NAUCHNO - ISSLEDOVATELSKY PROEKTNOKONSTRUKTORSKY I TEKHNOLOGICHESKY INSTITUT ELEKTROSVAROCHNOGO OBORUDOVANIA 8 April 1971 9042/71 Heading B3R [Also in Divisions G3 and H2] An A.C. arc welding system, for non-consumable argon-arc welding, comprises a transformer 1 in series with a saturable reactor 2, an electrode 12 and workpiece 13, controlled rectifiers 3, 4 being connected in parallel with the inductance and in antiparallel with each other. Inductance 2 is connected to the rectifiers 3, 4 via diodes 10, 11 so that at each half-cycle current through the inductance and through a corresponding controlled rectifier adds and passes through a corresponding current sensor 5, 6 each controlled by a current setting unit 9 set to a required value, a difference signal being applied to respective firing circuits 7, 8 to alter the firing angle of the rectifiers until the difference is null. Thus variations in mains supply and arc length may be compensated and a D.C. component eliminated by applying the same signals to both circuits 5, 6 or a particular D.C. value may be obtained by applying different signals. Impulse welding may be effected by the addition of a multivibrator into the circuit 9. If arc stabilization is not required, flip-flops may be used to fire the rectifiers 3, 4. In a 3-phase embodiment, Fig. 2 (not shown), identical systems are employed in each output of 3-phase transformer.