FRICTION STIR WELDING TOOL AND SPOT WELDING METHOD

PROBLEM TO BE SOLVED: To ensure the productivity equivalent to that of the conventional friction stir welding while ensuring the strength of a joined part by the friction stir welding by providing a spot welding method for permitting the raise of an upper plate during the welding and adequately limiting the raise by a friction stir welding tool. SOLUTION: The friction stir welding tool 11 includes a columnar body shaft part 12, a shoulder face 12a formed on an end on one side of the body shaft part 12, and a pin part 13 projected on the shoulder face 12a and having a pin part of the diameter smaller than that of the shoulder face 12a, and is used for the point welding of an object to be welded in which a plurality of base plate materials including at least an upper plate and a lower plate are layered. There is provided a raise preventive unit 14 which is projected from an outer circumferential surface of the body shaft part 12 outwardly in the radial direction. COPYRIGHT: (C)2010,JPO&INPIT