The invention relates to a clamp for
machining a round thin-walled workpiece. The clamp comprises a chuck body, fixing bases annularly arrayed on the chuck body and clamping jaws arranged on the fixing bases, wherein the front portion of each clamping jaw is folded to form a
hooking jaw used for clamping, the end of each
hooking jaw is provided with an inclination face, a
cushion block for abutting against the end face of the workpiece is installed on each fixing base at the inner side of the corresponding
hooking jaw, annular grooves are formed in the side walls of the workpiece, the ends ofthe hooking jaws stretch into the grooves, the inclination faces of the hooking jaws abut against notches of the grooves, and then the workpiece is driven to abut against the
cushion blocks. Accordingto the technical scheme, the inclination faces are utilized for abutting against the ports of the grooves in the side walls of the workpiece, and then radial clamping force and
axial thrust force towards the
cushion blocks can be provided for the workpiece. In this way, it is guaranteed that the clamping jaws can firmly clamp the workpiece, the clamp applies acting force to the workpiece throughthe inclination faces, the acting force can be broken down into small component force in the axial direction and radial direction of the workpiece, the risk of
radial deformation of the workpiece canbe effectively lowered, the circularity of the workpiece is guaranteed, and the yield is increased.