Patent ID: 9676055
Date: 2017-06-13
CPC Classifications: B23K,C22C

Claim:
1. A rotary tool for friction stir spot-welding, the rotary tool being configured to perform a friction stir spot-welding operation on a stack of two aluminum members, the rotary tool having a cylindrical tool body rotatable about its axis, and a probe which is provided in a central part of a distal end portion of the tool body so as to extend coaxially with the tool body, and which is inserted into the stack of the two aluminum members: wherein the probe has a stepped structure consisting of: a cylindrical intermediate probe having an outside diameter that is held within a range of 40-80% of an outside diameter of the tool body and projecting from the distal end portion of the tool body so as to extend coaxially with the tool body; and a cylindrical central probe having an outside diameter that is held within a range of 50-90% of the outside diameter of the intermediate probe and projecting from the intermediate probe so as to extend coaxially with the intermediate probe; and wherein a distal end face of the tool body provides a first shoulder surface which is gradually recessed in a radially inward direction so as to have an angle (θ