MONITORING MEHOTD OF LASER WELDING AND DEVICE THEREFOR

摘要

PROBLEM TO BE SOLVED: To precisely estimate the generation of a welding defect including the presence of a porosity within a weld metal by fitting the focal point or image pickup position to a plurality of desired depths within the key hole of a groove during laser welding, reading the respective light quantities in the depths, and analyzing the light quantities. SOLUTION: A power beam is emitted to the groove 11 of a work 10. The power beam is formed by a first optical system consisting of a laser beam source 12 such as YAG laser, a total reflecting mirror 13 and a condenser lens 14. On the other hand, the focusing or imaging surface fitting of a monitoring fiber 17a is performed by a second optical system consisting of a partial reflecting mirror 15a and a lens 16a so as to have the light quantity in the depth directional position 1 of the groove 11. The focusing or imaging surface fitting of monitoring fibers 17b, 17c is also performed by second and third optical systems so as to have the light quantities in the depth directional positions 2 and 3 of the groove 11. Accordingly, noise can be reduced by the set of a pinhole 22, and the light quantity in a depth position can be judged.