A wire electric discharge machine, configured to determine whether or not electrical discharge machining of a workpiece can be performed, includes a determination unit for determining that wire electrical discharge machining of the workpiece can be performed when a wire electrode is moved toward the workpiece and a contact detection unit detects contact, and for determining that the wire electrical discharge machining of the workpiece cannot be performed when a breaking detection unit detects the breaking of the wire electrode before the contact detection unit detects the contact.

A control device 8 controls a tension device 10 to apply a tension to a wire electrode WE such that a set tension value is as small as possible within a range of 80 g or less during a particular anneal period when a particular anneal current is supplied from a current supply device 5.

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 present invention provides a wire electrode supply apparatus for suppressing wire electrode driving vibration for wire electrodes having a wide range of diameters and formed of various materials, thereby improving processed surface roughness. The wire electrode supply apparatus includes a back tension adjustment unit that adjusts a back tension of the wire electrode drawn from a source bobbin, a tension applying unit, and a constant pressure ejecting unit that ejects the wire electrode with constant pressure and rate after the transference via the tension applying unit and an electrical discharge machining unit. The tension applying unit includes a low tension applying unit that applies a tension to the wire electrode, and a high tension applying unit that can supply a higher tension. After the high tension applying unit supplies a tension, the low tension applying unit supplies a tension. Otherwise, only the low tension applying unit supplies a tension.

An automatic wire connecting device includes a heating electrode that heats an electrode wire by applying a current to the electrode wire, a tension applying unit that applies a tension to the electrode wire to which the current is applied by the heating electrode, a tension control unit that controls the tension applied by the tension applying unit, and a power supply control unit that applies a heating current smaller than a preset annealing current to the electrode wire until a first set time elapses since the current starts to be applied and increases the current applied to the electrode wire to reach the annealing current during a second set time after the first set time elapses since the current starts to be applied.

A multiwire electric discharge machine includes: a machining power source that applies a machining pulse voltage between a workpiece and a cutting wire section; and a wire breakage detection unit that detects breakage of a wire electrode. The wire breakage detection unit is electrically connected in parallel to a wire electrode portion stretched over a section from one location on the feeding side of the wire electrode to one location on the ejection side of the wire electrode, and the wire breakage detection unit includes: a wire breakage detection circuit in which a wire breakage detection power source constantly supplying direct current to the wire electrode portion at least while the workpiece is undergoing a cutting process and a current limiting resistor are connected in series; and a wire breakage determination unit that determines breakage of the wire electrode based on current flowing through the current limiting resistor.