32 巻 (2014) 3 号 p. 207-212
We investigate how welding conditions affect the arc in TIG welding with a constricted nozzle by numerical simulation using an axial-symmetric two-dimensional model. When helium is used as a shielding gas, the effect of the constricted nozzle is more remarkable than argon. The heat flux to the center of the anode surface increases more with a higher welding current. This feature is suitable for pulsed welding. Even if an electrode is consumed and its tip angle is changed, a stable arc plasma and heat intensity are obtained.