2008 Volume 46 Issue 10 Pages 480-490
Laser welding of aluminum alloys is difficult because of their low laser coupling, easy formation of welding defects, etc., and thus the establishment of in-process monitoring technique is expected in various industries to obtain highly reliable laser welds. In this study, therefore, both the reflected laser beam and radiation light from the molten pool were investigated as monitoring signals during YAG laser welding of A5052 and A5182 aluminum alloy to confirm validity and usefulness of these signals for monitoring. At the same time, laser-welding phenomena were observed through a high-speed video camera to better interpret the monitored signals. Two signals were detected by utilizing photo sensors and band pass or cut off filters coaxially against a laser beam and from the above-back direction. In this paper, experimental setup, and monitoring and obsevation results were presented. The correlation between monitoring signals and welding phenomena was clarified when the welding defects such as underfilling and through-holes were formed.
