| 摘要 |
PROBLEM TO BE SOLVED: To dispense with threading process of an external thread part of a tip part outer peripheral surface of a support member and an internal thread part of inner peripheral surface of a chuck nut by maintaining coaxiality of the support member axis and the chuck nut axis in a close engage condition of a location regulation outer peripheral surface and a location regulation inner peripheral surface. SOLUTION: A collet member 3 comprises a holder member 5 attached to a tip part of a support member 2, plural collet claws 3a circularly arranged on the holder member 5 in radial pattern with maintaining a divided groove clearance R and griping a drill with a movement of contracting in radial direction by tightening action of a chuck nut 4. A location regulation outer peripheral surface 6 is formed on an outer peripheral surface of the support member 2 and a location regulation inner peripheral surface 7 regulating a relative location of the support member 2 and the collet claws 3a by close engagement with the location regulation outer peripheral surface 6 is formed in an inner peripheral surface of the chuck nut 5.
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