METHOD OF LASER WELDING METAL PLATED PLATE

PROBLEM TO BE SOLVED: To provide a laser welding method which dispenses with a special mechanism for forming minute gaps between metal plated plates and which ensures welding quality. SOLUTION: A laser head 13 is prepared that emits a laser beam 18 through a condensing lens 16 to converge the laser beam 18 at the focal position P of the condensing lens 16. Galvanized steel plates 11, 12 are superimposed closely without a gap. Then, the surface of the galvanized steel plate 12 in the superimposed part is irradiated with the laser beam 18 by the laser head 13, so that the steel plate portion in the laser irradiation region 19 is fused to form a welded joint. In this instance, for the purpose of making the irradiation region 19 of the laser beam 18 be the size in which no welding defect is generated in the weld zone by the jetting of zinc gas, the focal position P of the laser beam 18 is shifted upward from the surface of the galvanized steel plate 12. COPYRIGHT: (C)2011,JPO&INPIT