Abstract: A wire electric discharge machining apparatus having a structure for supplying power to a wire electrode, the structure being capable of prolonging the life of a power supply element and reducing a manufacturing cost and a running cost with a simple structure. There is provided a guide roller for guiding the wire electrode above and/or below the power supply element formed into a flat plate. The guide roller is driven by a small motor through a lead screw. An oscillating direction is perpendicular to a running direction of the wire electrode and parallel to a flat surface of the power supply element. A contact position of the wire electrode on the power supply element is varied in an area of a wide range, so that the contact position is not focused, thereby creating no groove or the like, that is attributable to friction, in the power supply element and extending the life thereof. The power supply element is formed into a simple flat plate, reducing the manufacturing cost thereof.

Abstract: There are determined by measurements: the maximum -A of the positional displacement, which is caused by a deflection when a machining point is moved in a +X direction; and a movement command D in effect until the machining point is reversed to a -X direction while the maximum deflection -A is maintained and the deflection A in the reverse direction is produced. It is assumed that the deflection proportionally changes from -A to +A while the movement command is outputted by D, that is, while the actual position of the machining point is moved by (D-2A). The correction amount is determined on the bases of the proportion of two times the deflection A with respect to (D-2A) and the movement command value after the reversal of the moving direction, and is added to the movement command value so that the resultant sum is outputted as the movement command value.