| 摘要 |
A conducting workpiece is machined by spark erosion using a travelling wire electrode, where the workpiece moves at 90 degrees w.r.t. the axis of the wire to form a gap fed with a liq. A sequence of electric pulses is applied to create a discharge in the gap, thereby removing material from the workpiece; and the electrode wire is oscillated at min. 100 Hz during spark erosion. The pref. frequency of wire oscillation is 1-50 kHz, with amplitude 1-50 (1-5) mu m. In the pref. machine, the wire travels under tension between two guides, and a vibrator is located near one guide to oscillate the wire. The pref. working liq. is water with specific resistance 5 x 102 to 5 x 104 ohm. cm.; a coolant may also be fed to one of the guides. The plane of wire oscillation pref. coincides with the cutting direction of the wire, and an oscillation parameter may be periodically altered. For accurate machining, the wire dia. is usually 0.05-0.5 mm., which previously limited the voltage which could be applied, as the wire broke due to arcing or short circuits. Oscillation of the wire interrupts arcs or short circuits, and also reduces friction of the guides, so wire breakage is eliminated and the rate of material removal is increased. |
