PURPOSE: To prevent the occurrence of a crater of a weld zone and a lowering of the weld strength by heating first only covering materials until these are vaporized and afterward, projecting a laser beam on base metals to join these metals in case of base metals to be welded which are covered by the covering materials with a lower melting point than the base metals.
CONSTITUTION: The covering material 10a of the 1st base metal 10 to be welded and the covering material 12a of the 2nd base metal 12 to be welded are superimposed and positioned so that these materials are faced mutually and a part 18 to be welded is heated by a torch 14 from the upper part of the base metal 12. The heating temperature is selected to the temperature where only the covering materials 10a and 12a are vaporized and the heated part of the covering materials is vaporized and made to a vaporizing body 20 and discharged from between both the base metals to the outside. Next, the laser beam 16a is projected on the part which is heated by the torch 14 by laser welding equipment 16 to join the base metals 10 and 12. Since the covering material of the part to be welded is already removed by the torch 14 in advance, even if the high-temperature laser beam is projected, the explosive vaporization of the covering materials does not take place and the surface without weld defects is obtained.
MIYAMOTO SHIGEO
NISHIGUCHI FUMIO
OGAWA YUKIO
