Method of manufacture of a structural body

摘要

The rotary tools are disposed to weld along two spaced welding lines. The two rotary tools are inserted into respective welding joints and moved at the same time along the respective welding lines. At a position P1 of a portion of a window one rotary tool is withdrawn from the welding joint to that the friction stir welding on that welding joint is stopped although the welding tool continues to move. At a position P3, the rotary tools are gradually withdrawn from their respective welding joints while they continue to move along the welding line. At a position P4, the movement of the rotary tools along the respective welding lines is stopped, the rotary tools are completely withdrawn and the welding is stopped. Next, the rotary tools are inserted into the respective welding joints once again and movement thereof is started again. An insertion amount of the rotary tools at this time is larger than the insertion amount thereof prior to the stopping of the movement of these rotary tools.