Novel Plasma Stabilization and Control of Titanium Welding Processes

Current commercially available systems for pulsed gas metal arc welding (GMAW-P) monitor electrical characteristics of the arc and attempt to compensate for process deviations by pulsing current at a constant frequency. For highly critical GMAW-P applications in challenging materials like titanium, the present approach cannot simultaneously control arc stability, bead shape, and weld metallurgy. Furthermore, the systems available today cannot preclude the occurrence of instabilities over certain ranges of travel speed and arc voltage. We propose a multi-sensor, multi-objective sensing and adaptive control method that senses arc electrical characteristics, the dynamics of individual droplets in the GMAW process, and the dynamics of the weld pool. We utilize reconfigurable, intelligent phase locked loop technology in conjunction with very high speed data acquisition, non-imaging optical weld pool sensors, and fuzzy logic controllers to achieve a comprehensive control solution that addresses the shortcomings of currently available systems. Such a system will allow for the first time multi-objective control of arc stability, bead shape, and weld metallurgy.