CLAMPING METHOD FOR WORK

PROBLEM TO BE SOLVED: To clamp a work on the main spindle head of a machine tool with a sufficient holding force without generating distortion. SOLUTION: A tapered work center 49 is provided in the tip of the main spindle 26 of a main spindle head 10, and a male screw 50 is formed in the tip of a rod 51 put through so as to be freely slid around the work center 49. A tapered center hole 53 and a female screw 54 are provided to be connected with each other in the end surface 52 of a crankshaft W and, by pulling the male screw 50 engaged with the female screw 54 by a piston 45, the center hole 53 of the crankshaft W is engaged and press-contacted with the work center 49 of the main spindle 26. Thus, the crankshaft W is clamped without generating any axial forces of a compressing direction in the same.