A collet-type mechanism for releasably gripping either an external or internal target surface of a tubular workpiece includes a collet receiver defining a collet receiver contact surface configured as a curved lateral surface of a truncated right circular cone, and a segmented collet assembly comprising a plurality of collet segments. Each collet segment defines a workpiece engagement surface configured for gripping engagement with a workpiece target surface, and a collet segment contact surface configured for at least partial contacting engagement with the collet receiver contact surface. The collet segment contact surface may comprise two axially-contiguous regions, one of which corresponds to a curved lateral surface of either an oblique circular cylinder or a right circular cylinder, and the other of which corresponds to a curved lateral surface of a truncated right circular cone.

A collet-type mechanism for releasably gripping either an external or internal target surface of a tubular workpiece includes a collet receiver defining a collet receiver contact surface configured as a curved lateral surface of a truncated right circular cone, and a segmented collet assembly comprising a plurality of collet segments. Each collet segment defines a workpiece engagement surface configured for gripping engagement with a workpiece target surface, and a collet segment contact surface configured for at least partial contacting engagement with the collet receiver contact surface. The collet segment contact surface may comprise two axially-contiguous regions, one of which corresponds to a curved lateral surface of either an oblique circular cylinder or a right circular cylinder, and the other of which corresponds to a curved lateral surface of a truncated right circular cone.

A chuck device includes: a cylindrical chuck including a first contact part on a first side and a second contact part on a second side, and configured to hold a bar-like workpiece; a tubular outer cylinder including a restriction part configured to restrict axial movement of the chuck by abutting on the first contact part; and a sleeve provided in an axially movable manner on the inner peripheral side of the outer cylinder, and including, on the first side, a pressing part axially driven to abut on the second contact part. The chuck includes a first tapered face in the first contact part, and a second tapered face in the second contact part. A first angle between the first tapered face and a center axis is equivalent to a second angle between the first tapered face and the center axis, or is smaller than the second angle.

A coupling device for coupling a hollow shaft taper to a receiver provided on the machine tool, having a collet and a tension rod by means of which the collet can be brought into a release position or a clamping position. The collet is embodied in one piece and has several clamping segments extending in its longitudinal direction. Upon moving the collet into the clamping position, said clamping segments are moved in a radial direction against spring forces exerted by the spring element. The spring elements are an integral part of the collet. Each spring element between two adjacent clamping segments is provided to extend in the longitudinal direction of the latter.

A chuck device includes: a cylindrical chuck including a first contact part on a first side and a second contact part on a second side, and configured to hold a bar-like workpiece; a tubular outer cylinder including a restriction part configured to restrict axial movement of the chuck by abutting on the first contact part; and a sleeve provided in an axially movable manner on the inner peripheral side of the outer cylinder, and including, on the first side, a pressing part axially driven to abut on the second contact part. The chuck includes a first tapered face in the first contact part, and a second tapered face in the second contact part. A first angle between the first tapered face and a center axis is equivalent to a second angle between the first tapered face and the center axis, or is smaller than the second angle.