Patent ID: 7800010

Claim:
A wire-cut electric discharge machine having a wire electrode tension control function and comprising a first motor for feeding a wire electrode to a workpiece to be machined, a second motor for delivering the wire electrode from the workpiece, and tension detecting means which is located between the workpiece and the first motor and detects a tension on the wire electrode, the wire-cut electric discharge machine further comprising: speed detecting means for detecting respective rotational speeds of the first and second motors; first control means for controlling the rotational speed of one of the first and second motors to be equal to a preset rotational speed; second control means for controlling a rotational torque of the other of the first and second motors so that the tension on the wire electrode detected by the tension detecting means is at a preset value; third control means for controlling the rotational speed of the other motor so that the tension on the wire electrode detected by the tension detecting means is at a preset value; and switching control means which causes the first control means to drivingly control the one motor, causes the second control means to perform torque control for the other motor, thereby running the wire electrode, and switches the second control means over to the third control means to perform speed control for the other motor when machining is started.