Chuck

A chuck (1) for supporting rotationally symmetrical workpieces (2) that are to be machined using a machine tool, the chuck (1) comprising:

• a chuck body (3) that has at least three guideways (5) worked into its end face running in the direction of the longitudinal axis (4) of the chuck (3);
• at least three clamping jaws (6) that are inserted individually into each of the guideways (5) in a movable arrangement;
• and
• a driving means (12) in a driving connection with the clamping jaws (6) via intermediate elements (8, 11), in which the driving means are configured as an electric motor (12), each of the at least three clamping jaws (6) having an electric motor (12) allocated to it, with each electric motor (12) being disposed inside the chuck body (3);
• wherein when the chuck (1) is stationary, the electric motors (12) are electrically connected to a power source (15) by means of a plug-and-socket connection (16) and electrical cables (14) and when the chuck (1) is rotating or at a standstill each electric motor (12) is connected to the power source via an induction device (21), wherein the induction device (21) comprises (i) a coupling section (22) mounted to the chuck body (3) such that the coupling section (22) rotates when the chuck body (3) rotates, and (ii) a charging section (23) which is stationary relative to the chuck body (3), and further wherein an uninterrupted gap of air separates the coupling section (22) from the charging section (23), such that power can be transmitted from the charging section (23) to the coupling section (22) across the uninterrupted gap of air while the chuck body (3) is rotating;
• wherein the chuck further comprises a control unit (24) configured to selectively, individually actuate one or more of the electric motors (12) so as to selectively, individually move one or more particular clamping jaws (6), whereby to keep a workpiece (2) centered in the chuck while the chuck is rotating;
• and
• wherein each of the clamping jaws (6) comprise a force accumulator device (31) configured to apply a force to that particular clamping jaw (6), wherein each force accumulator device comprises a spring for applying a force to the clamping jaws, and further wherein each force accumulator device is configured to maintain the position of each of the clamping jaws (6) when the one or more electric motors (12) are not applying a force to the clamping jaws (6).