Abstract
An in-process monitoring system has been developed for detecting the clearance between two steel sheets in CO2 laser welding lap joint of automotive body where photo sensors are used to separate the light emission of the keyhole plasma, PK, from that of the plasma plume, PP. The acquired signal involved AC components with frequencies up to approximately 10kHz of the light emission of the laser-induced plasma. Peak frequency of plasma emission induced in full penetration welding was found to decrease with increasing thickness of the workpiece. The mean square value of the AC component at a 4 - 6 kHz band was found to increase sharply at clearances larger than 0.3mm where the mechanical strength of the lap joint begun to decrease. The time-change in the light emission was found to be caused by the resonant oscillations of the keyhole surrounded by liquid wall.
Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
