A wire electric discharge machining apparatus includes: a processing tank, a lower-side wire guide assembly, a lower arm, a direction changing pulley, a winding roller, and a conveying device. The conveying device comprises a high-pressure jet flow generator and a suction pipe. The high-pressure jet flow generator is provided between the direction changing pulley and the winding roller on a side of a front end of a lower arm, and spouts a high-pressure jet flow toward a direction of the winding roller so that a wire electrode is guided only by a restraining force of the high-pressure jet flow and sent flying to the direction of the winding roller with the high-pressure jet flow. The suction pipe is provided on an exit side of the winding roller, and sucks and captures a tip of the wire electrode sent by the high-pressure jet flow.

A wire electric discharge machining apparatus includes: a processing tank, a lower-side wire guide assembly, a lower arm, a direction changing pulley, a winding roller, and a conveying device. The conveying device comprises a high-pressure jet flow generator and a suction pipe. The high-pressure jet flow generator is provided between the direction changing pulley and the winding roller on a side of a front end of a lower arm, and spouts a high-pressure jet flow toward a direction of the winding roller so that a wire electrode is guided only by a restraining force of the high-pressure jet flow and sent flying to the direction of the winding roller with the high-pressure jet flow. The suction pipe is provided on an exit side of the winding roller, and sucks and captures a tip of the wire electrode sent by the high-pressure jet flow.

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 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.

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.

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 detection unit configured to detect a contact state in which the wire electrode contacts the workpiece, and a contact release state in which the wire electrode that is in the contact state is separated from the workpiece; a vibration unit configured to, if the contact state is detected during the machining of the workpiece, stop relative movement of the wire electrode and vibrate the wire electrode about a stop position at which the relative movement of the wire electrode has been stopped; and a relative movement control unit configured to resume relative movement of the wire electrode if the contact release state is detected until a predetermined time elapses from when the contact state has been detected or until the number of times that the wire electrode is vibrated reaches a predetermined number of times.