Wire electrode supply apparatus and wire electrode supply method

A wire electrode supply method employed in a wire electrical discharge machining device comprising an electrical discharge machining unit that provides electrical discharge machining using a wire electrode, the wire electrode supply method comprising:

• back tension adjustment in which a back tension adjustment unit adjusts a back tension applied to the wire electrode drawn from a source bobbin;
• tension applying in which a tension applying unit adjusts a tension applied to the wire electrode drawn from the source bobbin, at the electrical discharge machining unit;
• and
• constant pressure ejecting in which a constant pressure ejecting unit ejects the wire electrode with a constant rate in a state in which the wire electrode is pinched with a constant pressure after the wire electrode passes through the tension applying unit and the electrical discharge machining unit,
• wherein the tension applying unit comprises a high tension applying unit and a low tension applying unit disposed downstream of the high tension applying unit, and each configured to apply a tension to the wire electrode;
• wherein the low tension applying unit is configured to supply a tension in a range up to a reference tension value,
• wherein the high tension applying unit is configured to supply a tension that is higher than the reference tension value,
• wherein, during the tension applying, when the tension applying unit is to supply a tension that is higher than a switching tension value, which is equal to or lower than the reference tension value, the low tension applying unit applies a tension to the wire electrode after the high tension applying unit applies a tension to the wire electrode by providing a braking load, and
• wherein, during the tension applying, when the tension applying unit is to supply a tension that is lower than the switching tension value, only the low tension applying unit applies a tension to the wire electrode and the high tension applying unit provides no braking load and applies no tension to the wire electrode.