A device for clamping a workpiece comprises a chuck body and a drive fastened thereto, and at least one clamping jaw, which is coupled to the drive in a driveable arrangement either directly or via intermediate elements and which is or are held movably in or on the chuck body in the direction of the workpiece. This is achieved by providing a free space between the chuck body and a clamping jaw carrier accommodating the clamping jaw, in that an elastically deformable sleeve is inserted in the free space, which sleeve rests on the outside of the chuck body at two positions spaced apart from one another, and in that a pressure chamber is created between the chuck body, the sleeve, and the two support positions into which a medium can be filled, whereby to bulge the latter in the direction of the clamping jaw carrier between the support positions.

A device (1) for clamping a workpiece (2) to be machined, in particular a chuck or vice, the device comprising: (i) a chuck body (3) and a drive (5) fastened thereto, and (ii) at least one clamping jaw (6), which is coupled to the drive (5) in a driveable arrangement either directly or via intermediate elements (7) and which is or are held movably in or on the chuck body (3) in the direction of the workpiece (2). On the one hand, reliable and centric clamping of the workpiece (2) in a predetermined position is achieved and, on the other hand, the mounting of the clamping jaw carrier (9) on the chuck body (3) is free of backlash in the clamped condition in order to prevent any possibility of movement of the workpiece (2) relative to the chuck body (3). This is achieved by providing a free space (11) between the chuck body (3) and a clamping jaw carrier (9) accommodating the respective clamping jaw (6), in that an elastically deformable sleeve (12) is inserted in the free space (11), which sleeve (12) rests on the outside (8) of the chuck body (3) at two positions (21) spaced apart from one another, and in that a pressure chamber (14) is created between the chuck body (3), the sleeve (12) and the two support positions (21) thereof, into which pressure chamber (14) a medium (16) can be filled, by means of which a pressure force directed outwards acts on the wall (W2) of the sleeve (12) and bulges the latter in the direction of the clamping jaw carrier (9) between the support positions (21).

This present disclosure relates to a device for rotary entrainment of a workpiece clamped between two tips, which is mounted on a machine table of a machine tool, consisting of a base body with a centrically arranged tip and a plurality of concentrically arranged, axially shiftable driver elements which for the rotary entrainment of the workpiece are pressed against or into an end-face surface, wherein an axial position of the driver elements can be defined by active fixation after a centering operation of the workpiece, and to a receptacle opposite the base body, for example a tip or hollow tip, which serves a guidance of an opposite side of the workpiece.

Provided is a material to be worked in face driving, which can facilitate making a face driver hold the material and can prevent a slide in the rotating direction between the face driver and the material, and a method for working the material. The material is to be worked with one end surface thereof held by the face driver having a center pin and a plurality of driving claws arranged around the center pin. A center hole into which the center pin is fit is formed on the one end surface. A recess or a protrusion existing in every phase in a circumferential direction around the center hole is formed on the one end surface. The recess or the protrusion is arranged within an area of the one end surface in a radial direction of the one end surface, into which the driving claws are driven.