Simultaneous Monitoring of Penetration Status and Joint Tracking During Laser Keyhole Welding

Abstract

Visual monitoring is currently a research hotspot in the monitoring of laser welding. In this paper, an active coaxial monitoring system for laser keyhole welding is built. This system reduces the intense light interference caused by the laser, plasma plume, and specular reflection of the molten pool. The significant differences in the temperatures of the joint, keyhole, and molten pool are also overcome. Images that include the clear keyhole, penetration hole, and joint are captured by the single-sensor monitoring system. The ratio of the penetration hole area to the keyhole area and the fault-tolerant disposal based on the permissive area scope of the keyhole are used to propose an algorithm for judging the penetration status. The deviations between the keyhole centroid and the joint centerline and the fault-tolerant disposal based on the maximum allowable slope change rate of the joint centerline are used to track the joint. Experiments are also performed to monitor the penetration status and to track the joint tracking simultaneously. The experimental results show that the method of simultaneous monitoring that is proposed in this paper is feasible. This single-sensor and multitarget monitoring method will provide basis for the online control of the laser welding process.