Friction stir welding tool and friction stir welding apparatus

A method of setting dimension of a friction stir welding tool which comprises:

• a first shoulder surface configured to contact a front surface of a subject work piece;
• a second shoulder surface disposed so as to face the first shoulder surface and being configured to contact a rear surface of the work piece;
• a shaft portion connecting the first shoulder surface and the second shoulder surface to each other with a fixed gap therebetween, wherein
• a groove is provided on at least one of the first shoulder surface and the second shoulder surface,
• the groove extends in a predetermined tool rotation direction so as to extend toward an outer peripheral side in the first shoulder surface or the second shoulder surface,
• the method comprising a step of determining a gap between the first shoulder surface and the second shoulder surface in an axial direction of the shaft portion by the following equation (1),
• T1<=WLMS−ΔL (1)
• where:
• T1 is the gap between the first shoulder surface and the second shoulder surface in an axial direction of the shaft portion;
• and
• WLMS is a minimum allowable thickness of the work piece;
• ΔL is a thermal expansion amount in the axial direction of the shaft portion during friction stir welding.

A method of setting dimension of a friction stir welding tool which comprises:

• a first shoulder surface configured to contact a front surface of a subject work piece;
• a second shoulder surface disposed so as to face the first shoulder surface and being configured to contact a rear surface of the work piece;
• a shaft portion connecting the first shoulder surface and the second shoulder surface to each other with a fixed gap therebetween, wherein
• a groove is provided on each of the first shoulder surface and the second shoulder surface,
• the groove extends in a predetermined tool rotation direction so as to extend toward an outer peripheral side in the first shoulder surface and the second shoulder surface,
• the method comprising a step of determining a gap between bottom portions of the grooves in an axial direction of the shaft portion by the following equation (2),
• T2>=WMMS−ΔL (2)
• where:
• T2 is the gap between the bottom portions of the grooves in an axial direction of the shaft portion;
• WMMS is a maximum allowable thickness of the work piece;
• and
• ΔL is a thermal expansion amount in the axial direction of the shaft portion during friction stir welding.

A method of setting dimension of a friction stir welding tool which comprises:

• a first shoulder surface configured to contact a front surface of a subject work piece;
• a second shoulder surface disposed so as to face the first shoulder surface and being configured to contact a rear surface of the work piece;
• a shaft portion connecting the first shoulder surface and the second shoulder surface to each other with a fixed gap therebetween, wherein
• a groove is provided on one of the first shoulder surface and the second shoulder surface,
• the groove extends in a predetermined tool rotation direction so as to extend toward an outer peripheral side in the first shoulder surface and the second shoulder surface,
• the method comprising a step of determining a gap between a bottom portion of the groove, and the other of the first shoulder surface and the second shoulder surface in an axial direction of the shaft portion by the following equation (3),
• T3>=WMMS−ΔL (3)
• where:
• T3 is the gap between the bottom portion of the groove, and the other of the first shoulder surface and the second shoulder surface in an axial direction of the shaft portion;
• WMMS is a maximum allowable thickness of the work piece;
• and
• ΔL is a thermal expansion amount in the axial direction of the shaft portion during friction stir welding.