Patent ID: 6272956
Filing Date: 2001-08-14
Classification: B23B,Y10T

Abstract:
A device for holding a workpiece or a bar of a material to be machined in a chuck of a rotating spindle of a machine tool, the device comprising:a first spring element that exerts a first axial force to the chuck;a spindle body that is rotatable within a fixed spindle support;a thrust tube disposed coaxially within the spindle body, said thrust tube being axially slidable relative to said spindle body, the axial movement of said thrust tube controlling a tightening or a loosening of the chuck;a regulating tube disposed coaxially between a rear portion of the spindle body and a rear portion of the thrust tube, said regulating tube being fixed axially;a first socket receiving the first spring element, the first socket is circumferentially bounded between said regulating tube and said thrust tube and axially bounded on one side by a first annulus-shaped face of a first wall fastened to the regulating tube, and on the other side by a second annulus-shaped face of a shoulder fastened to the thrust tube, said first axial force exerted by said first spring element tending to move the first and second annulus-shaped faces apart thereby moving the thrust tube along said first axial direction; andat least one tightening-pressure chamber defined between at least one second wall fastened to the regulating tube and at least one third wall fastened to the thrust tube, said tightening-pressure chamber being supplied with a first air pressure that exerts a second axial force on a face of the at least one third wall, which is a wall disposed substantially perpendicular to a longitudinal axis of said spindle, the first and second axial forces being exerted along a first axial direction parallel to the longitudinal axis of the spindle to exert a gripping force.