Hybrid a free arc into constraint-arc to improve arc pressure control behavior

Abstract

Decoupling the arc pressure and heat output improves the controllability of the arc. In this study, an innovative torch was successfully developed for this purpose by adding an outer electrode under the orifice to a conventional plasma arc welding (PAW) torch. The arc rooting from the added electrode merges with the main/PAW arc forming a hybrid arc system with two cathodes and one anode. While the major arc is constrained, the added arc is allowing to change the anode heat while the pressure is still primarily controlled by the main arc. The coupling behavior was experimentally studied through analysis arc column image and arc pressure measurement. The results show that the added free arc formed by the outer electrode is fully absorbed and coupled into the constraint arc to form a single hybrid arc. The arc pressure peak value in the hybrid arc is little sensitive to outer free arc current compared with that by adjusting the center constraint arc current. Because the sided outer tungsten electrode is isolated to the center inner tungsten electrode and the cooper nozzle in the arcing torch system, the range of arc current applied by the outer tungsten electrode is large. The torch system provides a novel arc plasma generation method to improve the control precision in manufacturing process.