PROCEDE ET APPAREIL DE SOUDAGE SOUS GAZ PROTECTEUR ISOLANT ET A ELECTRODE DE TUNGSTENE

A TIG welding apparatus comprises a welding current supply means for supplying an electric current, a shield gas supply means for supplying shield gases, a tungsten electrode connected to the welding current supply means, a welding torch disposed coaxially around the tungsten electrode and provided with inner and outer double gas shields having gas jetting nozzles through which the gases are jetted, a plurality of wires to be fed to a portion at which the gases are jetted through the gas jetting nozzles, a wire feeding means, and a heating means connected to the wires, except at least one wire, for heating the wires. A TIG welding method is carried out by using such welding apparatus through the steps of supplying shield gases into the inner and outer gas shields and jetting the shield gases through the jetting nozzles to a portion at which a welding arc is generated, feeding continuously wires, except at least one wire, under a condition heated by the heating means to that portion as hot wires through the wire feeding means and feeding continuously the at least one wire under a condition not heated to the portion as cold wire through the wire feeding means substantially at the same time of the feeding of the hot wires.