AC TIG welding apparatus using hot wire

Abstract

An unconsumable electrode such as tungsten is opposingly arranged with a base metal to be welded. An AC arc welding power supply is connected between the base metal and the unconsumable electrode. A filler wire such as of aluminum is fed by a wire feeder toward an arc-generated part between the base metal and the unconsumable electrode. Also included is a wire-heating power supply for producing a pulsed current. The wire heating power supply heats the filler wire by supplying thereto a pulsed current in accordance with a sync signal from the AC arc welding power supply or a detection signal of an arc current i.sub.A or an arc voltage of the AC arc power supply. The filler wire is thus heated by being supplied with a heating current i.sub.W in pulse form while the unconsumable electrode is kept negative by an AC arc formed between the unconsumable electrode and the base metal. During the period when the unconsumable electrode is kept positive by the AC arc, the filler wire is not supplied with any current or is heated by being supplied only with a sufficiently small current not to cause any substantial magnetic flow. Accordingly, even if a large current flows through the wire, arc interruptions can be eliminated, thereby improving the welding process of aluminum by using an AC TIG arc.

Dependencies are inferred from the claim text.