To provide a friction stir welding method with which the welding of a butted part formed by fitting a recessed part with a projecting part, can be satisfactorily performed.
The tip parts of shapes 10, 20 are butted. The trapezoidal projecting part 22 of the shape 20 enters the trapezoidal recessed part 12 of the shape 10. Friction stir welding is performed by inserting a rotary tool 50 from the projecting parts 13, 23 sides. The small diameter part 51b of the rotary tool 50 is in a tapered shape and a screw part 51b is provided. A large diameter part 53 is a different member from the shaft part of the rotary tool 50, and is connected with a pin 59. The screw of the screw part 51b can be provided up to the vicinity of the recess 53g of the end face of the large diameter part 53, and the near part of the end face can be sufficiently stirred. Therefore, satisfactory friction stir welding can be performed.
FUKUYORI KAZUNARI
MATSUNAGA TETSUYA
HITACHI KASADO KIKAI CO LTD