To prevent the magnetism blowing phenomenon of arc and to stabilize the behavior of the arc by arranging a member for attracting the arc up to one side of the arc and irradiating a base material with the arc under condition of attracting the arc up to the member, as it is.
Magnetic field is generated around the arc 5 with the current of the arc 5. In the case that a steel piece 3 of the material having high magnetic permeability exists at one side of the arc 5, the arc 5 is attracted to the direction of the steel piece 3 by the shortening action of the line of magnetic force and the tip part thereof is slanted so as to approach the steel piece 3 and stabilized in this posture. Therefor, even if some variation in the magnetic field distribution is developed around the arc 5, the arc 5 is not easily swung to the direction separated from the steel piece 3 and the magnetism blowing phenomenon can be prevented. Under keeping the arc 5 in this posture, a torch 1 is shifted along the surface of the base plate 4 and then, the arc is shifted to the same locus as the torch 1. In this way, the arc 5 can accurately irradiate the desired position on the surface of the base plate 4 and a TIG treatment can suitably be executed.
TAKEMOTO YUICHI
TANAKA HIROSATO
