Double-electrode GMAW process and control

Double-electrode gas metal arc welding (DE-GMAW) is a novel process that decouples the melting current into base metal current and bypass current by adding a bypass torch to a conventional GMAW system to establish a bypass arc. This makes it possible to increase the melting current while the base metal current can be controlled at a desired level. Experiments have been done to find the conditions that can assure a stable bypass arc is established/maintained between the welding wire and the bypass torch. To control the base metal current at the desired level, a group of power resistors is added in the bypass loop. The resistance of the power resistor group is adjusted real-time by changing the combination of the resistors, and the change in the resistance results in a change in the bypass current and 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. Experiments demonstrated that the developed control system can adjust the bypass current in a great range to maintain the base metal current at the desired levels.