| 摘要 |
PURPOSE:To prevent crushing and breakage of an electrode wire and to improve wire cut electric discharge machining precision, by a method wherein the fluctuation in tension of the electrode wire is sensed, and a wire tension sensing roller to control the press force of a pinch roller according to control of the tension is mounted to an arm. CONSTITUTION:When tension exerted on an electrode wire 14 is increased, a wire tension sensing roller 54 forces an arm 52 to perform revolving motion in the direction of an arrow mark P around a fulcrum 50. AS a result, a pinch roller 38, mounted on the side opposite to the roller 54 with the fulcrum therebetween to the one point of the arm 52, is pressed by a main roller 36 by means of a high press force through the action of a spring 40. Inversely, when tension exerted on the electrode wire 14 is decreased to a low value, the roller 54 is displaced in a direction reverse to the arrow mark P togetherwith the arm 52 against the force of the spring 40. As a result, the pinch roller 38 is slightly displaced in a direction, in which it is separated away from the main roller 36 to decrease a press force. This constitution controls the press force of the pinch roller 38 according to control of tension, and prevents breakage of the electrode wire 14.
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