BROACHING MACHINE

PURPOSE:To enable the alignment of a workpiece, prevent the eccentric wear of a broach and improve machining accuracy by providing on a broaching machine a workpiece fixing device and an error compensation means for X, Y and turning directions to correct errors of a detected workpiece center and a broaching center. CONSTITUTION:When a broaching machine has been turned 'ON', a detector 21 is fed downward by the feeding device 22 thereof and stops at a predetermined position, thereby making a contact needle 23 touch the internal surface of a square hole 31 on a workpiece 31 for measuring the center position thereof. And each measured value is fed back to X, Y and rotary table drive devices 18, 15 and 20 respectively, and positional compensation therefor is made so that corresponding errors DELTAx, DELTAy and DELTAtheta will be zero. After this positional compensation, a lower table 11 is shifted to the broach B side along the guide 8 of a base 6, actuated by a lower table drive device 13. Then, a workpiece 31 is clamped by a clamping device 4, a broach 1 comes down driven by a hydraulic motor 5, a square hole 31a is finished to high precision by the broach 1 and the broaching machine is turned 'OFF'.