BENDING MACHINE

PROBLEM TO BE SOLVED: To provide a bending machine which helps to minimize variations of bending angles by improving accuracy of up and down movements in an upper side clamp beam. SOLUTION: The upper side clamp beam 9 provided with a top die 17 to press-fix a workpiece from the up and down direction cooperating with a bottom die 13 is provided by rocking universally in the up and down direction. The upper side clam beam is rockingly driven in the up and down direction by a crankshaft 23 for clamping which is rotationally driven with a hollow synchronous motor 27 for clamping. The hollow synchronous motor consists of a hollow rotor directly connected with an end of the crankshaft for clamping and a motor housing to support the rotor. The crankshaft for clamping is rotationally driven by the hollow synchronous motor without a reducer directly at a high torque and a low speed. Thus, by controlling the rotational angle accurately, positioning accuracy in the up and down direction of the upper clamp beam is improved.