| 摘要 |
PROBLEM TO BE SOLVED: To prevent generation of a recess in a weld zone by abutting the end of a second member on the end of a first member excluding a part projecting from its face in the thickness direction, inserting a rotary body, which has a small diameter part at the tip end of a large diameter part, in the manner that the boundary between the large and small diameter parts is located between the extension of the face and the apex of the projection, and revolvingly moving the rotary body along the abutted part for welding. SOLUTION: The small diameter parts 72 of the two rotary bodies 70, 70 are inserted revolvingly into the weld zone of hollow sections 50, 60 and moved simultaneously along the longitudinal direction of the weld zone. The boundaries 73 between the large and small diameter parts 71, 72 of the rotary bodies 70, 70 are located between the extension of the outside face of the plates 51, 61 excluding the thick parts 56, 66 and the apexes of the thick parts 56, 66. The small diameter part 72 is in the abutted part. Even if a gap exists between the thick parts 56, 66 and the end part 56a, 66a, the base material of the thick parts 56, 66, which is fluidized by friction stirring welding, is pressed into the gap, preventing defect generation in the weld zone. Its upper face is machined by a grinder and made coplanar with the upper surfaces of the plates 51, 61. |
