Collet chuck

A collet chuck comprising:

• a mandrel on which a truncated conical outer tapered surface is formed at a tip portion and which is fixed at a center position;
• a first collet that is positioned outside the mandrel, in which a cylindrical collet main body section is divided in a circumferential direction, and an intermediate claw formed at each tip portion of the collect main body section has an inner tapered surface formed on an inner side in sliding contact with the outer tapered surface of the mandrel;
• a second collet that is positioned outside the first collet, in which a cylindrical collet main body section is divided in a circumferential direction, a chuck claw formed at each tip portion of the collet main body section has an inner sliding contact surface formed on an inner side in sliding contact with an outer sliding contact surface formed on an outer side of the intermediate claw, and a chuck surface formed on an outer side of the chuck claw is brought into contact with a workpiece;
• and
• a collet support member that receives a force in an axial direction and supports the first collet movably in the axial direction.