Patent ID: 9308594
Filing Date: 2016-04-12
CPC Classification: B23H

Claim Text:
1. A wire electrical discharge machining apparatus comprising: a collecting roller that collects a wire electrode; a collecting motor that causes the wire electrode to travel at a predetermined speed by driving the collecting roller; a tension roller that applies tension to the wire electrode between the tension roller and the collecting roller; a tension motor that drives the tension roller; a speed calculating unit that calculates a rotational speed of the tension motor; a speed fluctuation compensating unit that generates a speed compensation value that suppresses fluctuation of a rotational speed of the tension motor on a basis of a rotational speed output from the speed calculating unit; and a breakage detecting unit that detects a breakage of the wire electrode on a basis of a comparison of a preset breakage detection threshold and a speed compensation value output from the speed fluctuation compensating unit, wherein the speed compensation value is generated before detecting a speed difference between a wire speed at the tension roller and a wire speed at the collecting roller.