Tool for friction stir welding

A tool for friction stir welding comprising:

• a tool part abutting a workpiece while being rotated;
• a shank part configured to fix the tool part to a front end of the shank part and be rotated together with the tool part;
• and
• a screw having a groove formed at its outer periphery thereof for fixing the tool part to the front end of the shank part,
• wherein portions in the tool part and the shank part at which the tool part and the shank part contact each other have at least one from between a convex section and a concave section, in order to enable movement of the tool part with respect to the shank part in a direction parallel to an axis of rotation of the shank part while movement of the tool part with respect to the shank part in a direction around the axis of rotation of the shank part is restricted, by the convex section and the concave section of the tool part and the shank part being fitted to each other,
• the shank part has a shank part hole section wherein the screw is capable of reaching the tool part fixed to the front end of the shank part passing through the shank part,
• the tool part has a tool part screw hole section having a groove, at an inner periphery, meshing with the groove of the outer periphery of the screw passing through the shank part hole section, and
• after the convex section and the concave section of the tool part and the shank part are fitted to each other, the tool part is fixed to the front end of the shank part, by the groove of the outer periphery of the screw passed through the shank part hole section meshing with the groove of the inner periphery of the tool part screw hole section, and
• an inner periphery of the shank part hole section having a groove with an inner diameter larger than an inner diameter of the tool part screw hole section, and capable of screwing in a tool part detachment screw having a groove on an outer periphery of the tool part detachment screw meshing with the groove of the inner periphery of the shank part hole section such that the tool part is pushed out by the tool part detachment screw and the tool part becomes detached from the shank part.