Patent ID: 7322509

Claim:
A friction stir spot joining device for softening and stirring works to be joined due to friction heat generated by rotation of a pin so as to join the works to be joined together and provided with a pressing motor and a stirring motor fixed to one end side of an arm, a jointing tool having the pin at a tip end thereof and connected to an output shaft side of the stirring motor at a rear end thereof, said stirring motor and said jointing tool being disposed on the same axis line, said friction stir spot joining device further including: a ball nut fixed to the rear end side of the stirring motor; wherein the output shaft of the stirring motor has a hole in which a ball screw is housed from a rear portion of the hole so as to be positioned in the hole; and wherein a rotating force of the pressing motor is transmitted to the ball screw and the stirring motor is moved forward and backward by the ball nut threaded with the ball screw.