Modeling and Control of Double-Electrode Gas Metal Arc Welding Process

Double-electrode gas metal arc welding, referred to as DE-GMAW, is a novel process developed recently to increase the welding productivity while maintaining the base metal current at a desired lower level. In this process, a bypass torch is added to a conventional GMAW system to decouple the melting current into base metal current and bypass current and the base metal current can be effectively controlled through adjusting the bypass current. To assure the base metal current be controlled at the desired level, this paper proposes to add a group of power resistors in the bypass loop and to change the resistance of the power resistor through changing the combination of the resistors. A change in the resistance results in a change in the bypass current thus a change in the base metal current. A model has been developed to correlate the change of the resistance needed to achieve the desired base metal current to the deviation of the base metal current from its desired level. A method has been proposed to implement the needed resistance change through adjusting the combination of the resistors. Experiments verified that the developed control system can adjust the bypass current in a large range to achieve the desired base metal current.