This invention provides a machine tool capable of easily and quickly attaching/detaching a tool holder while reliably holding the tool holder, including at least two clamp holes (211) that receive pins (203) extending through at least two through holes (202) provided in a tool holder (134), at least two tubular clamp sleeves (302) fitted in the at least two clamp holes (211), respectively, and each including a flexible trunk portion (321), a fluid encapsulating chamber that encapsulates a fluid, a channel extended from the fluid encapsulating chamber to an outer peripheral surface of the flexible trunk portion, and a pressure adjusting portion that adjusts a pressure of the fluid in the fluid encapsulating chamber, wherein a clamp fastening force is made to act on the pins (203) in synchronism with an increase or a decrease in the fluid pressure in the fluid encapsulating chamber.

A collet chuck including a mandrel, a first collet that is positioned outside the mandrel, an intermediate claw formed at each tip portion 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, a chuck claw formed at each tip portion 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.

A hydraulic expansion chuck for receiving a tool includes a chuck body, an expansion bushing which is received in the chuck body and defines a chuck opening, a pressure chamber which is interposed between the expansion bushing and the chuck body, and a reduction sleeve. The reduction sleeve is received in the chuck opening of the expansion bushing and defines a tool holder receptacle for receiving the tool to be chucked. The reduction sleeve includes a connector element configured to releasably attach the reduction sleeve to the chuck body. The reduction sleeve also may include an adjustment element configured to adjust the axial position of the tool in the tool holder receptacle.

The invention relates to a hydraulic expansion chuck (1) with a hydraulic expansion mechanism (23) that is integrated into a chuck body (10, 20) and exhibits an expansion bushing (23a) with a continuous cylindrical interior wall, and to a reducing bushing (24) arranged in the expansion bushing (23a) for accommodating a shank tool (W), in particular a tap drill. According to the invention, the outer circumference of the reducing bushing (24) is positively connected with the chuck body (10, 20) in a torque-proof manner, and its inner circumference is designed to be positively connected with the shank tool (W) in a torque-proof manner.