Patent ID: 6998561

Claim:
A wire electric discharge machine for machining a workpiece by electric discharge between the workpiece and a wire electrode arranged between upper and lower wire guides, comprising: storage means storing a straightness-error corrective amount to prevent a straightness error of a wire electrode caused by consumption of the wire electrode due to the electric discharge; and motion path determination means to obtain a first correction amount for a motion path of the wire electrode on a first plane parallel to the workpiece in an offset direction of the wire electrode and a second correction amount for a motion path of the wire electrode on a second plane parallel to the workpiece in the offset direction, based on the straightness-error corrective amount stored in said storage means, and to correct the motion path on the first plane by a first corrected offset amount obtained based on the first correction amount and a predetermined offset amount depending on a wire radius and an electric discharging gap, and to correct the motion path on the second plane by a second corrected offset amount obtained based on the second correction amount and the predetermined offset amount, to thereby determine motion paths of the upper and lower wire guides relative to the workpiece, wherein said storage means comprises a database provided in a controller of the wire electric discharge machine for storing a plurality of straightness-error corrective amounts for different kinds of wire electrodes and machining conditions, and the straightness-error corrective amount is selected from the plurality of straightness-error corrective amounts stored in the database in accordance with a kind of the wire electrode and a machining condition designated for the wire electric machining in the controller.