método de soldagem a ponto por fricção e mistura mecânica

A tool driving section (53) of a friction stir spot welding device is configured to cause each of a pin member (11) and a shoulder member (12) to advance and retract, and is controlled by a tool driving control section (21). A press-fit reference point setting section (22) sets a position where the pin member (11) or the shoulder member (12) contacts an object to be welded (60) as a press-fit reference point, and the tool driving control section (21) controls the position of the pin member (11) with respect to the shoulder member (12) on the basis of the press-fit reference point, thereby controlling the press-fit depth of a rotating tool (51) press-fitted from the surface of the object to be welded (60). This achieves the excellent welding quality at suitable precision according to welding conditions especially in a double-acting friction stir spot welding method.