In a wire electric discharge machine, a control unit is configured to deposit constituents of a wire electrode between a workpiece and a portion to be cut off from the workpiece to bond the workpiece and the portion to be cut off by outputting a signal for making an output voltage of a variable DC power supply lower than during normal machining and the on-time of a second switching element longer than during the normal machining, at least in a part of a machining path.

A power supply device for an electric discharge machine includes a current supply unit for supplying a pulsed current to an electrode gap and a current regeneration unit for regenerating the current. The current supply unit includes a DC power supply, a first switching element, and a second switching element. The current regeneration unit includes a capacitor arranged between a first connection point between an electrode and the first switching element and a second connection point between a workpiece and the second switching element, and a third switching element which is arranged between a third connection point between the first connection point and the DC power supply and a fourth connection point between the second connection point and the capacitor and which is turned on from the start of current regeneration until the current value reaches zero, whereby regeneration current fall time is reduced.

A power supply device for an electric discharge machine includes a DC power supply which is connected in parallel to an electrode gap, a plurality of switching elements which are in parallel to each other and which are arranged between the electrode gap and the DC power supply, a current value acquisition unit for acquiring a value of a current, and an ON-OFF control unit which, during the time when the current value reaches a predetermined value until the time when the current starts to fall, sets a cycle for switching the plurality of switching elements from off to on to the same cycle, switches the plurality of switching elements from off to on in a predetermined order for each timing of a phase of 90°, which is 360° divided by the number of the plurality of switching elements, sets an ON-period of each of the plurality of switching elements based on a difference between the value of the current and the predetermined value, and performs ON-OFF control of the plurality of switching elements based on the cycle, the timing, and the ON-period.

A wire electrical discharge machine includes: a pulse detection unit configured to detect voltage pulses repeatedly applied between a workpiece and a wire electrode; an instability calculation unit configured to calculate the degree of instability indicating how unstable the discharge state is, by using the number of non-discharge pulses that present no voltage drop due to electrical discharge, among the pulses detected per unit time by a pulse detection unit; and a machining condition changing unit configured to change a machining condition for the workpiece, based on the calculated degree of instability.

A wire electrical discharge machine performs electrical discharge machining on a workpiece by applying voltage across an electrode gap formed between a wire electrode and the workpiece to thereby generate electrical discharge while moving the wire electrode relative to the workpiece along a path specified by a machining program. The wire electrical discharge machine includes: a voltage detector for detecting a gap voltage across the gap; a facing area calculation unit for calculating, as a facing area, the area of a surface of the workpiece contained within a predetermined distance from the center axis of the wire electrode; an axis feed rate determination unit for determining an axis feed rate based on the gap voltage value detected by the voltage detector, and the facing area; and a movement control unit for performing control so that the wire electrode moves relative to the workpiece at the axis feed rate.

A drive circuit configured to drive a load. The drive circuit comprises a transformer. The transformer comprises a transformer primary comprising one or more primary windings connected to arms that pass through a magnetic material. The transformer also comprises a transformer secondary comprising secondary windings connected to planar secondary conductors which pass through the inside of the arms. The drive circuit also comprises a voltage source configured to apply a voltage across the transformer primary.

A method for controlling a wire electrical discharge machining process, wherein the method comprises the following steps: dividing a workpiece height H.sub.WP into a number N.sub.S of vertical sections S of the workpiece, setting a defined observation period T.sub.M, N.sub.DTM, with each discharge Di, determining a discharge position of each discharge, counting the number of discharges determining any numbers of discharges and adjusting at least one process parameter.

A method for controlling a wire electrical discharge machining (WEDM) process, in which the wire traveling speed V.sub.W is adapted in-process, while cutting. The method includes, determining the size of the crater occurring at each said determined position of each discharge along the engagement line of a wire and a work piece, and the current wire traveling speed; and continuously comparing the wire wearing model with one or more wire wearing limits, and adjusting the wire traveling speed according to the comparison of the actual wire wearing model and the one or more wire wearing limits. The wire electrical discharge machining process is conducted with reduced wire consumption, safely, efficiently and profitably.

A power supply device for an electric discharge machine includes a current supply unit for supplying a pulsed current to an electrode gap and a current regeneration unit for regenerating the current. The current supply unit includes a DC power supply, a first switching element, and a second switching element. The current regeneration unit includes a capacitor arranged between a first connection point between an electrode and the first switching element and a second connection point between a workpiece and the second switching element, and a third switching element which is arranged between a third connection point between the first connection point and the DC power supply and a fourth connection point between the second connection point and the capacitor and which is turned on from the start of current regeneration until the current value reaches zero, whereby regeneration current fall time is reduced.

An upper guide assembly includes an upper wire guide, an upper power feed contact, and a power feed contact movement device, and a lower guide assembly includes a lower power feed contact. The upper power feed contact and the lower power feed contact are configured to contact the wire electrode to supply power by moving in a horizontal direction from initial positions not contacting the wire electrode. The power feed contact movement device is configured to move the upper power feed contact in the horizontal direction from the initial position by a predetermined offset amount. The offset amount is set based on a machining condition including at least one of a condition of the wire electrode, a condition of a workpiece, and a surface roughness required for a cut surface of the workpiece.