Patent ID: 8680422

Claim:
A wire electrical discharge machine that machines a workpiece under conditions in which a wire electrode is stretched between an upper wire guide and a lower wire guide, a voltage is applied to a machining gap between the wire electrode and a workpiece so that an electrical discharge occurs, relative positions of the wire electrode with respect to the workpiece are changed, and a working fluid is being supplied to the machining gap from an upper working fluid feeder installed in the upper wire guide and a lower working fluid feeder installed in the lower wire guide, the wire electrical discharge machine comprising: a discharge pulse current discriminating unit that discriminates, with respect to a discharge pulse current introduced into the machining gap, between an effective discharge pulse contributing to machining of the workpiece and an ineffective discharge pulse not contributing to the machining of the workpiece; an ineffective discharge pulse number counting unit that counts the number of the ineffective discharge pulses that are discriminated every predetermined time; an electrical discharge position detecting unit that detects an electrical discharge position by measuring current values on a plurality of conduction paths provided in the machining gap every predetermined time and comparing the respective measured current values; a machining-chips unevenly distributed state discriminating unit that discriminates an unevenly distributed state of machining chips in the machining gap based on the counted number of the ineffective discharge pulses and the detected electrical discharge position; and a working-fluid flow-rate adjusting unit that adjusts balance between a flow rate or a pressure of the working fluid supplied from the upper working fluid feeder and a flow rate or a pressure of the working fluid supplied from the lower working fluid feeder based on the discriminated unevenly distributed state of the machining chips so that the unevenly distributed state of the machining chips is eliminated.