Tool or workpiece chucking device

A chucking device for a tool or workpiece having a cylindrical or slightly conical chucking surface comprising (a) a body, which is provided with a truncated cone-shaped surface, (b) a cavity located in said body inside of said cone-shaped surface of said bodies and along a substantial portion of the axial extension of said cone-shaped surface of said body and (c) a fluid-utilizing pressurizing member located in said body, by means of which member said cavity can be subjected to pressure as desired by means of said fluid, and (d) a holder for the tool or workpiece which is provided with a surface having a cone-shaped shape substantially corresponding to that of said body, a cylinder-shaped surface concentric with said cone-shaped surface of said holder, and with slits open at one end and extending through the wall of said holder, and (e) a clamp ring, which can be screwed on threads arranged in said body concentrically with said cone-shaped surface of said holder for causing said cone-shaped surface of said holder to contact said cone-shaped surface of said body.