Criterion for online evaluation of penetration status in laser-MIG hybrid welding and its application

The root penetration status in hybrid butt welding is the most important criterion for evaluating the weld joint quality. The weld root width can be easily acquired and recognized by vision sensor system in real time. Thus the weld root width was proposed as the criterion for evaluating penetration status in CO₂ laser-MIG hybrid welding. According to the weld root width, the penetration status can be divided into three categories: Partial, Moderate Full, and Excessive. The impacts on the penetration status with the variation of welding parameters and gap width were further investigated. Then penetration status detection and control system has been set up adopting vision sensor in CO₂ laser-MIG hybrid welding with gapped butt. Therefore, based on the criterion of weld root width, the closed-loop control of penetration status is realized in gapped butt hybrid welding.