| 摘要 |
End portions of members (10,20) are butted against each other with a trapezoidal convex portion (22) inserted into a trapezoidal concave portion (12). Friction stir welding is performed by inserting a rotary tool (50) from the side of upper convex portions (13,23). A small diameter portion of the rotary tool (50) is tapered, and is provided with a screw thread (51b). A large diameter portion (53) is provided by a member different from a shaft portion of the rotary tool (50) on which it is fixed. The screw thread (51b) of the screw portion extends into a recess of the end surface of the large diameter portion (53), so that stirring near this end surface can be performed sufficiently. <IMAGE> |
