Provided is a chuck structure, which is configured to chuck an annular workpiece from a radially outer side of the workpiece. The chuck structure includes: leaf spring members arranged at a predetermined pitch along a circumferential direction of the chuck structure so as to be symmetrical with respect to a mechanism center axis; chuck claw members mounted to distal ends of the leaf spring members, respectively; and a pressing force applying mechanism configured to apply a force of pressing the leaf spring members radially inward, to thereby elastically press the chuck claw members onto a radially outer surface of the workpiece.

A bit retention device has an upper support member having an inner surface and an outer surface. A lower support member fixed to the upper support member. A stationary plate is mounted to the inner surface of the upper support member. A clamp plate opposes the stationary plate and is spring biased toward the stationary plate and slidably moveable between the upper support member and the lower support member.

A chuck for a power tool includes a chuck body extending along a longitudinal axis. The chuck also includes a plurality of jaws, each with a jaw end, and each movable along a respective jaw axis between a closed position and an open position. Each respective jaw axis is oriented at an oblique angle relative to the longitudinal axis. A biasing member is coupled to the jaws and is operable to bias the jaws toward the closed position. The biasing member includes a spring. The chuck also includes a rotating assembly selectively engageable with the jaws such that, when engaged, the jaws are movable in response to rotation of the rotating assembly. The biasing member includes a guide sleeve coupled to each of the jaws and movable axially along the longitudinal axis in response to each of the jaws moving along its respective jaw axis.

A work holder includes: a first holding part having three attracting members that are arranged circumferentially apart from each other to attract an axial end face of an annular work; and a second holding part having a contacting member that is held in contact with an inner periphery or outer periphery of the work and restricts radial movement of the work.

Provided is a chuck structure, which is configured to chuck an annular workpiece from a radially outer side of the workpiece. The chuck structure includes: leaf spring members arranged at a predetermined pitch along a circumferential direction of the chuck structure so as to be symmetrical with respect to a mechanism center axis; chuck claw members mounted to distal ends of the leaf spring members, respectively; and a pressing force applying mechanism configured to apply a force of pressing the leaf spring members radially inward, to thereby elastically press the chuck claw members onto a radially outer surface of the workpiece.

A bit retention device has an upper support member having an inner surface and an outer surface. A lower support member fixed to the upper support member. A stationary plate is mounted to the inner surface of the upper support member. A clamp plate opposes the stationary plate and is spring biased toward the stationary plate and slidably moveable between the upper support member and the lower support member.

A chuck for a power tool includes a chuck body extending along a longitudinal axis. The chuck also includes a plurality of jaws, each with a jaw end, and each movable along a respective jaw axis between a closed position and an open position. Each respective jaw axis is oriented at an oblique angle relative to the longitudinal axis. A biasing member is coupled to the jaws and is operable to bias the jaws toward the closed position. The biasing member includes a spring. The chuck also includes a rotating assembly selectively engageable with the jaws such that, when engaged, the jaws are movable in response to rotation of the rotating assembly. The biasing member includes a guide sleeve coupled to each of the jaws and movable axially along the longitudinal axis in response to each of the jaws moving along its respective jaw axis.

A bit retention device has an upper support member having an inner surface and an outer surface. A lower support member fixed to the upper support member. A stationary plate is mounted to the inner surface of the upper support member. A clamp plate opposes the stationary plate and is spring biased toward the stationary plate and slidably moveable between the upper support member and the lower support member.

A chuck includes a chuck body extending along a longitudinal axis, the chuck body including a plurality of slots each arranged at an oblique angle with respect to the longitudinal axis. A plurality of jaws each includes a first engagement portion, a jaw end, and a drive end. Each of the jaws is disposed within one of the plurality of slots and is movable between a close position and an open position. A biasing member is coupled to the plurality of jaws and is operable to bias the plurality of jaws toward the close position and a rotating assembly is selectively engageable with the plurality of jaws such that when engaged, the plurality of jaws are movable in response to rotation of the rotating assembly.

A work holder includes: a first holding part having three attracting members that are arranged circumferentially apart from each other to attract an axial end face of an annular work; and a second holding part having a contacting member that is held in contact with an inner periphery or outer periphery of the work and restricts radial movement of the work.