Friction stir welding method

摘要

The end of a face plate 11 of one hollow member 10 is abutted against the end of a face plate 21 of another hollow member 20. The end of the face plate 21 overlaps a protrusion 15. A small diameter portion 52 of a friction stir welding tool 50 is inserted into the abutted area, and the tool 50 is moved along the abutted region into the plane of the paper of the figure, while being rotated in the rightwards direction observed from the large diameter portion 51. The pressure of mobilized metal is greater on the right side of the axial centre of the rotary tool. The thickness of the member 10 from the tip of the inserted small diameter portion 51 to the hollow areas 10b and 10a is greater at the right side, where the pressure is higher, thus preventing metal from flowing out into the hollow region 10a. Since the member 10 is thinner at the left side of the tool, the weight of the welded member is reduced.