Abstract
In the former reports, it was discussed that a TIG arc behavior was controlled by a CO2 laser when the traveling speed of a base metal was fast and the arc length was long. In this case, the bead width was different, although the experimental conditions were same except the traveling direction of the base metal. In this report, the behavior of the TIG arc only was investigated using high speed video images when the traveling direction was changed. Furthermore, the reasonable spot of CO2 laser was examined for stabilization of the arc. In this case, the backward direction meant that the traveling direction was same as the direction of a tungsten electrode. The opposite direction was called the forward direction. The main experimental conditions were as follows. The TIG arc current, the traveling speed of a SUS304 base metal, Ar gas flow rate and the distance between the base metal and a tungsten electrode were 100 A (DCEN), 150 mm/s, 1×10-3 m3/s and 15 mm, respectively. When the base metal moved to the backward direction, a straight arc column bent smoothly at the point which was near to the base metal, and moved straightly to an anode spot. This spot existed in the circular molten pool and the shape of the pool did not changed. In this case, the bending point scarcely changed its position. On the other hand, in the case of the forward direction, the shape of the bending arc column, the position of the bending point and the shape of the melted part were different from ones of the backward direction. It was considered that arc stiffness at the bending point of the backward direction arc and preheat effect of arc plasma were less than the ones of the forward direction arc.
