Rotating member for friction stirring, welding apparatus, and welding method

A welding apparatus for performing friction stir welding of a welding object member, the welding apparatus comprising:

• a driving mechanism including an output shaft, the driving mechanism being configured to rotate the output shaft;
• and
• a pin portion rotatable by a rotational force received from the driving mechanism, the pin portion being inserted into the welding object member at a time of friction stirring, wherein, a clearance is formed at one or more positions between the pin portion and the output shaft, the clearance being void or substantially void and the pin portion is freely movable or substantially freely movable relative to the output shaft within a range allowed by the clearance, the clearance allowing the pin portion to vibrate relative to the output shaft such that at a time of friction stirring a vibration of the pin portion has a larger amplitude and/or a higher frequency than a base vibration of the output shaft.

A rotating member for friction stir welding a welding object member, the rotating member connectable with an output shaft of a rotatable driving mechanism, the rotating member comprising:

• a pin portion receiving structure configured to connect a pin portion with the rotating member;
• wherein, when rotating member is connected with the output shaft and the pin portion is connected with the rotating member via the pin receiving structure, one or more clearances are formed at one or more positions that are axially disposed, circumferentially disposed, or radially disposed relative to a longitudinal axis of the output shaft, the one or more clearances disposed between the pin portion and the output shaft, the one or more clearances being void or substantially void and the pin portion is freely movable or substantially freely movable relative to the output shaft within a range allowed by the one or more clearances, and,
• wherein, the one or more clearances allow the pin portion to vibrate relative to the output shaft within the range defined by the one or more clearances.