| 摘要 |
PROBLEM TO BE SOLVED: To prevent a wire electrode from being broken during the preparation operations before electric discharge machining. SOLUTION: When a wire electrode is arranged along a traveling path by manual operation, a motor M1 for feeding the wire electrode to a workpiece is driven in response to a predetermined torque command from a control section 30 with a switch SW1 on a side a. The wire electrode is prevented from being broken by facilitating the manual operation. The wire electrode is connected, and a motor M2 for delivering the wire electrode from the workpiece is driven at a predetermined speed, whereby the electrode is run. Then, the switch SW1 is shifted to a side b and a switch SW2 to the side a, and the motor M1 is subjected to torque control such that a tension on the wire electrode detected by a tension detector 6 is equal to a command tension. When a variation of the tension on the wire electrode is converged, the switches SW1 and SW2 are shifted to the side b, speed control of the motor M1 is performed so that detected tension is equal to the command tension, and electric discharge machining is started. Though the tension on the wire electrode is varied due to static frictional force during the start of running of the wire, the wire electrode can be prevented from being broken by the torque control of the motor M1. COPYRIGHT: (C)2008,JPO&INPIT
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