The chuck mechanism includes: a chuck body 10; an axially movable plunger 40 disposed inside the chuck body; and a master jaw 20 radially movable by wedge action caused by fitting the plunger in the master jaw 20. A guide groove 11 that radially guides the master jaw and has a T-shaped cross section is formed in the chuck body. The master jaw has a narrow portion 23 and a wide portion 24 that form a T-shaped cross section. A wedge 21 fitted in a wedge groove 41 of the plunger is formed radially inside the wide portion. The end face 21a of the wedge in the width direction is positioned outward in the width direction with respect to the end face 23a of the narrow portion in the width direction.

A machine tool includes: a hollow spindle including a hollow portion along an axial direction; a plurality of chuck claws openably mounted at a distal end portion of the hollow spindle, and configured to hold a workpiece; an operation rod inserted into the hollow portion of the hollow spindle in a movable manner, and configured to close the plurality of chuck claws with movement of the operation rod toward one side in the axial direction and open the plurality of chuck claws with movement of the operation rod toward the other side in the axial direction; and a measuring apparatus configured to measure an opening dimension of the plurality of chuck claws based on a movement amount of the operation rod.

A workpiece holding device includes: a chuck including a chuck body, and a plurality of chuck claws openably supported on the chuck body and configured to hold a workpiece; an operation rod configured to drive the plurality of chuck claws for opening and closing with movement of the operation rod; and a measuring apparatus configured to measure an opening dimension of the plurality of chuck claws based on a movement amount of the operation rod.

A chuck mechanism of the present invention includes multiple master jaws placed movably in a radial direction on a front surface of a chuck body, and top jaws each detachably attached to front surfaces of the top jaws. Each master jaw and each top jaw have a raised portion and a recessed portion engageable with each other. Each of the raised and recessed portions has conical surfaces formed by part of a conical body. Each top jaw has a gripping surface formed by part of a circular columnar body. Upon work gripping, the center axes of the conical surfaces on a gripping side among the conical surfaces of each master jaw and each top jaw and the center axis of the gripping surface are all coincident with a rotation axis of the chuck body.

The disclosure provides a compact and low-cost gripper which allows an outside diameter of a piston to be increased. Provided is a gripper including a body case having, at one end, a cylinder part having a cylinder chamber which houses a piston so as to slide the piston along a central axis of the piston, and having, at the other end, a plurality of guide parts formed at regular intervals around the center axis and extending in a direction orthogonal to the center axis; a plurality of master jaws, on which top jaws can be removably mounted, guided by each of the guide parts; and a plunger having a plurality of interconnecting means which are respectively interconnected with each of the master jaws and slides along the central axis associated with a sliding operation of the piston.

A compensating chuck for concentrically clamping workpieces. The chuck has a drive unit having two pairs of entrainment members, wherein the entrainment members are preferably slidingly mounted, are respectively movable in paired relationship, and are so coupled to a respective one of the main jaws that a relative movement of a respective pair causes a synchronous movement of adjacent main jaws and that both a relative movement relative to each other with respectively different movement components and also a synchronous movement of the adjacent entrainment members in the same direction respectively causes a relative movement of adjacent main jaws.

A power chuck includes a housing in which there is arranged a drive unit having a traction guide means moveable in the direction of a clamping axis. There are arranged two pairs of mutually diametrically opposite base jaws. The base jaws are guided radially, in the housing substantially perpendicularly to the clamping axis, and the drive unit is adapted to convert the movement of the traction guide means into the movement of the base jaws. According to the invention, it is proposed that the drive unit for each base jaw has a slider which is in engagement with the base jaw and which is moveable with a movement component on a circular path about the clamping axis.

A compensation chuck for centrically clamping workpieces includes a housing, two pairs of mutually diametrally opposite base jaws for receiving corresponding clamping jaws, and a drive unit which is moveable preferably by power clamping having two pairs of drivable entrainment members. Two adjacent entrainment members are respectively coupled together by a first rocker and two further adjacent entrainment members are coupled together by a second rocker. There is also provided a coupling ring which guides a first entrainment member and a diametrally opposite second entrainment member in the peripheral direction tangentially relative to the clamping axis, such that a motion play is provided between the entrainment members and the coupling ring in the radial direction.

A compensation chuck for centrically clamping workpieces includes a housing, two pairs of mutually diametrally opposite base jaws for receiving corresponding clamping jaws, and a drive unit which is moveable preferably by power clamping having two pairs of drivable entrainment members. Two adjacent entrainment members are respectively coupled together by a first rocker and two further adjacent entrainment members are coupled together by a second rocker. There is also provided a coupling ring which guides a first entrainment member and a diametrally opposite second entrainment member in the peripheral direction tangentially relative to the clamping axis, such that a motion play is provided between the entrainment members and the coupling ring in the radial direction.

A chuck for gripping a workpiece includes: a chuck body; a jaw connected to the chuck body for constrained movement relative to the chuck body along a jaw path in jaw-closing and jaw-opening directions; an actuator body connected to the chuck body for constrained movement relative to the chuck body along an actuator path; and a slider body connected to the chuck body for constrained movement relative to the chuck body along a slider body path. The slider body is connected to the jaw for constrained movement relative to the jaw along a slider-body-to-jaw path. The slider body is connected to the actuator body for constrained movement relative to the actuator body along a slider-body-to-actuator-body path.