A wire electrical discharge machine includes a first voltage applying circuit, a second voltage applying circuit, and a switch controller. The first voltage applying circuit includes a first DC power source for applying a positive polarity voltage across an electrode gap, and a first switch for on/off-switching of application of the positive polarity voltage. The second voltage applying circuit includes a second DC power source for applying a reverse polarity voltage to the electrode gap, and a second switch for on/off-switching of application of the reverse polarity voltage. The switch controller controls the first switch and the second switch so that the first switch and the second switch are not turned on simultaneously. The first DC power source and the second DC power source are set up so that the absolute value of the reverse polarity voltage is lower than the absolute value of the positive polarity voltage.

A wire electrical discharge machine includes a guide pipe arranged in a path along which a wire electrode is fed from a feed roller to a workpiece, and formed with an insertion hole through which the wire electrode is inserted, a compressed air supply device configured to supply compressed air to the insertion hole so that compressed air flows through the insertion hole along a feed direction of the wire electrode, a database configured to store data indicative of a relationship between rigidity information of the wire electrode and pressure information of compressed air, and a controller configured to set pressure of the compressed air supplied to the insertion hole, based on the rigidity information of the wire electrode fed to the workpiece and the data.

A wire electrical discharge machine includes a guide pipe arranged in a path along which a wire electrode is fed from a feed roller to a workpiece, and formed with an insertion hole through which the wire electrode is inserted, a compressed air supply device configured to supply compressed air to the insertion hole so that compressed air flows through the insertion hole along a feed direction of the wire electrode, a database configured to store data indicative of a relationship between rigidity information of the wire electrode and pressure information of compressed air, and a controller configured to set pressure of the compressed air supplied to the insertion hole, based on the rigidity information of the wire electrode fed to the workpiece and the data.

A wire electrical discharge machine having an auto wire feeding function includes: guide parts arranged on a wire feed path along which the wire electrode is fed so as to guide the feeding of the wire electrode; fluid paths formed with the guide parts to supply a compressed fluid to the wire feed path; a compressed fluid supply device to supply the compressed fluid to the fluid paths; a tension detector to detect the tension of the wire electrode; and a control device that controls the compressed fluid supply device so as to supply the compressed fluid to the fluid paths, and based on the detection result from the tension detector, determines whether or not the wire electrode has reached a supply position of one of the fluid paths on the wire feed path to which the fluid has been supplied.

A wire electrical discharge machine having an auto wire feeding function includes: guide parts arranged on a wire feed path along which the wire electrode is fed so as to guide the feeding of the wire electrode; fluid paths formed with the guide parts to supply a compressed fluid to the wire feed path; a compressed fluid supply device to supply the compressed fluid to the fluid paths; a tension detector to detect the tension of the wire electrode; and a control device that controls the compressed fluid supply device so as to supply the compressed fluid to the fluid paths, and based on the detection result from the tension detector, determines whether or not the wire electrode has reached a supply position of one of the fluid paths on the wire feed path to which the fluid has been supplied.

The wire electric discharge machining device includes a wire bobbin configured to wind and hold a wire electrode, a wire delivery roller configured to draw the wire electrode from the wire bobbin and deliver the wire electrode continuously toward a work-piece, a brake motor configured to apply a load to the wire bobbin in a direction against the drawing of the wire electrode, rotation speed detector configured to detect a rotation speed of the wire bobbin, an emptiness determination device configured to determine that the wire bobbin reaches an empty state based on a rapid change in the rotation speed of the wire bobbin detected by the rotation speed detector, and a drive control part configured to stop the drive of the wire delivery roller when the emptiness determination device determines that the wire bobbin reaches the empty state.

The wire electric discharge machining device includes a wire bobbin configured to wind and hold a wire electrode, a wire delivery roller configured to draw the wire electrode from the wire bobbin and deliver the wire electrode continuously toward a work-piece, a brake motor configured to apply a load to the wire bobbin in a direction against the drawing of the wire electrode, rotation speed detector configured to detect a rotation speed of the wire bobbin, an emptiness determination device configured to determine that the wire bobbin reaches an empty state based on a rapid change in the rotation speed of the wire bobbin detected by the rotation speed detector, and a drive control part configured to stop the drive of the wire delivery roller when the emptiness determination device determines that the wire bobbin reaches the empty state.

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 for controlling a wire electrical discharge machining (WEDM) process according the invention includes adapting the wire traveling speed in-process, wherein the method comprises the steps of: determining the position of each discharge along the engagement line of a wire and a work piece; determining the size of a crater provoked at the wire by each discharge; creating a real time wire wearing model based on the position of each discharge along the engagement line of the wire and the work piece, and based on 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 based on 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.

The present disclosure relates to a waste wire recovery apparatus, which includes: a waste wire recovery unit recovering a waste wire discharged from a wire electric discharge machine while rotating; and a rotational actuator rotating the waste wire recovery unit. Since the waste wire recovery unit rotates when recovering a waste wire, the waste wire can be uniformly received in the waste wire recovery unit. Accordingly, the stack density of the waste wire received in the waste wire recovery unit is improved, so the amount of a waste wire that can be transported at one time on a vehicle, etc. can be increased. Accordingly, the economic efficiency of reusing a waste wire can be improved.

A wire electrical discharge machine for performing electrical discharge machining on a workpiece to be machined by applying voltage to an electrode gap formed between a wire electrode and the workpiece to generate electrical discharge at the electrode gap under predetermined machining conditions while conveying the wire electrode along a transfer path, includes: a wire breakage detector for detecting a breakage of the wire electrode; a position calculator for calculating the breakage position of the wire electrode in the transfer path; and an adjustment unit for adjusting the machining conditions when the breakage position is in a predetermined section of the transfer path.