| 摘要 |
To perform both-side friction stir welding superior in economy and high in joint strength, first and second rotary tools 3, 4 include tool bodies 3a, 4a having shoulder portions 3c, 4c formed at tip end portions, respectively, the first rotary tool 3 further includes a protruding portion 3d formed to protrude from the tip end portion of the tool body and the second rotary tool 4 further includes a recessed portion 4d formed at the tip end portion thereof for,receiving the tip end of the protruding portion 3d therein when two metal plates 1, 2 are to be welded. The first and second rotary tools are arranged in opposed relationship in the front and back surface sides of a joint portion J of the metal plates, moved to approach to each other to insert the tip end of the protruding portion of the first rotary tool into the recessed portion of the second rotary tool while pressing shoulder surfaces 3b, 4b of the shoulder portions of the first and second rotary tools against the front and back surfaces of the joint portion. In this state, the first and second rotary tools are moved along the joint portion to frictionally stir the entire region in the thickness direction of the joint portion. |
