Consumable Double-Electrode GMAW Part II : Monitoring , Modeling , and Control Selecting bypass arc

FEBRUARY 2008, VOL. 87 -s 44 ABSTRACT. Consumable doubleelectrode gas metal arc welding (DEGMAW) is an innovative welding process that can significantly increase the deposition rate without raising the base metal heat input to an undesired level. To be qualified as a practical manufacturing process, feedback control is required to ensure the presence and stability of the bypass arc. To this end, the bypass arc voltage was selected to monitor the state of the bypass arc. Further, the authors proposed an interval control algorithm for models whose parameters are bounded by given intervals. This algorithm does not require the specific values for parameters, but only their intervals, which can be identified through a selected set of experiments. By conducting step responses under different conditions, a few models were obtained and the parameter intervals were determined and enlarged to increase the stability margin. Using the obtained parameter intervals in the interval control algorithm, closed-loop control experiments have been conducted to verify the effectiveness of the proposed control system for the consumable DE-GMAW process.