Patent ID: 7638726

Claim:
A wire electric discharge machining apparatus comprising: a discharge-generation control unit that applies at least a preliminary-discharge voltage pulse and a main-discharge voltage pulse between a wire electrode and a work in sequence to generate a pulse electric discharge; a plurality of current measuring units that measure discharge currents flowing between the electrodes in a plurality of current-carrying paths; a discharge-position determining unit that determines, when calculating discharge positions from results of measurement by the current measuring units, a discharge position at the time of at least second application of the preliminary-discharge voltage pulse; and a machining-energy adjusting unit that sets one of the discharge position calculated by the discharge-position determining unit at the time of the application of the preliminary-discharge voltage pulse, a discharge position predicted from a discharge position, where an electric discharge occurred in the past, calculated from the main-discharge voltage pulse immediately preceding the preliminary-discharge voltage pulse, and a discharge position calculated by the discharge-position determining unit at the time of application of a voltage pulse generated before the application of the preliminary-discharge voltage pulse as a discharge position determined before the application of the main-discharge voltage pulse, compares, as required, the discharge position determined before the application of the main-discharge voltage pulse and the discharge position calculated by the discharge-position determining unit at the time of the application of the main-discharge voltage pulse and reflects a result of the comparison on determination of a discharge position performed before application of the main-discharge voltage pulse performed next time, adjusts a pulse width or a voltage of the main-discharge voltage pulse, and feeds a result of the adjustment to the discharge-generation control unit to cause the discharge-generation control unit to reflect the result on the generation of an electric discharge.