| 摘要 |
PURPOSE:To prevent oxide sludge from sticking to a workpiece, by making a machining voltage into reversed polarity as long as the specified time periodically, and further making the duration of a cycle so as to be shortened according to the machining depth, in case of an electric discharge machining device using a dielectric fluid containing water. CONSTITUTION:A noncombustible dielectric fluid containing water is fed to a space between an electrode 14 and a workpiece 12 from a nozzle 32 and pulse voltage out of a power source 16 is impressed on the electrode and the workpiece whereby electric discharge machining takes place. A polarity conversion controller 22 detects an electric condition, an average machining current and the like of the power source and, according to the detected value, gives a polarity conversion device 20 a command for a reversion of machining voltage for the specified time in an optimum period. Simultaneously with this reversion, the controller 22 performs an electrode jumping motion, an increment in machining fluid feed pressure, etc. In addition, a machining depth is detected by a measuring device 23 and controls the reversing period so as to be shortened in proportion to an increase in the machining depth. |
