SHRINK-FIT TOOL UNIT, TOOL HOLDER USED FOR THE SHRINK-FIT TOOL UNIT, AND ROTARY TOOL

摘要

[PROBLEMS] To provide a shrink-fit tool unit in which the ability to transmit rotation power is increased and the workability when a rotary tool is inserted into a tool holder is improved, the tool holder used for the shrink-fit tool unit, and the rotary tool. [MEANS FOR SOLVING THE PROBLEMS] The shrink-fit tool unit is formed such that a first engagement part (11a) can be engaged with a second engagement part (22b) by merely inserting a cylindrical connection part (11) of a cold forming tap (10) into a chuck part (22)(hollow part (22a)) of the tool holder (20). Even if a working load from a workpiece acts on the tool unit circumferentially in the normal and reverse directions, the ability to transmit rotation power can be increased. Since the first engagement part (11a) of a cold forming tap (10) is formed symmetrical with respect to the axis (O1) of the cylindrical connection part (11), the direction of inserting the cold forming tap (10) into the chuck part (22)(hollow part (22a)) of the tool holder (20) is not limited to one direction. Consequently, workability can be improved.