Effects of Filler Wire Intervention on the Gas Tungsten Arc: Part III — Process Stability Control of Wire-Filled GTAW

Abstract

Stability control of the welding process is necessary to guarantee weld quality. In this study, a sensing method that collects both global and local arc information was proposed to conveniently monitor metal transfer stability during gas tungsten arc welding. This sensing method was also used to monitor the stability of the weld surface height by sensing the change in global arc length. The stability factor (fmt) was calculated to quantify the metal transfer stability. The characteristic signal (U*), which represents the average global arc voltage in the presence of a liquid bridge, was extracted to characterize the change in arc length by decoupling the dynamic interference signal of metal transfer. Both a fuzzy controller and a proportional integral derivative controller were designed to control the metal transfer stability and the weld surface height. The preliminary control experiments proved the effectiveness and potential of the proposed sensing and control strategies.