Evaluation criterion and closed-loop control of penetration status during laser-MIG hybrid welding

Laser-MIG hybrid welding is an advanced joining process and is widely applied in various industries. It is important to make sure the plate is fully penetrated with an appropriate weld formation in practical applications. In this paper, 3 kW CO2 laser and pulse MIG machine were used to compose the laser-MIG hybrid welding equipment to make butt weld of stainless steel plates. The penetration status was divided into three types: partial penetration, moderate full penetration, and excessive penetration. The effect of welding parameter and gap width on penetration status was investigated experimentally. The weld root width was detected by real-time vision sensor system and proposed as the criterion for evaluating penetration status in CO2 laser-MIG hybrid welding. The closed-loop control system was established with vision sensor and digital signal processor. Consequently, the weld with consistent "moderate full penetration" was acquired in laser-MIG hybrid butt welding with great variation of gap width by autoadjusting the welding speed or welding current. (C) 2010 Laser Institute of America.