Double-electrode gas metal arc welding: The process, sensing, modeling and control

Gas Metal Arc Welding (GMAW) is one of the most widely used processes for joining of metals because of its good quality and high productivity. However, one of its fundamental characteristics (the base metal current is equal to the melting current, and all the current will flow through the workpiece.) restricts the further increase in the welding productivity. Thus, a novel process, referred to as Double-Electrode Gas Metal Arc Welding or DE-GMAW, has been proposed to change this fundamental characteristic such that the welding productivity can be increased independent of melting current.;DE-GMAW 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. Thus it is possible to increase the melting current while the base metal current still be controlled at a desired level because the increased part of the melting current would be bypassed without flowing through the workpiece. Depending on the type of the bypass electrode, the DE-GMAW process can be implemented as either non-consumable DE-GMAW or consumable DE-GMAW. In non-consumable DE-GMAW the bypass electrode is non-consumable Tungsten while in consumable DE-GMAW the bypass electrode is a consumable welding wire.;Extensive studies have been conducted to uncover the fundamental characteristics of the DE-GMAW process. The process has been modeled and controlled with an interval model control algorithm. Experiments verified that the proposed system can stabilize the process very well in a large range of welding parameters. More importantly, experiments also confirmed that the process is capable of doubling the welding productivity and reducing the base metal heat input.;Keywords. Gas Metal Arc Welding, Double-Electrode, Welding Productivity, Heat Input, Metal Transfer...