2025 年 30 巻 p. 23-
In electrical discharge machining, various discharge current waveforms such as square, sawtooth, and sine waveforms have been used by various researchers, and machining speed and tool electrode wear change depending on the waveform. In this study, thermo-fluid analysis in single-pulse discharge was conducted using square and sawtooth waveforms in which the current increases with time, and the effects of discharge current waveforms on the formation of discharge craters were verified. The analysis results showed that, for the sawtooth waveform with increasing current with time, a large recoil pressure owing to the material evaporation was generated at the end of the discharge when the discharge current became large, and the outward velocity at the molten region of the discharge crater became large. Furthermore, single-pulse discharge experiments showed that the sawtooth waveform resulted in a larger removal volume. In addition, in the sawtooth waveform, the pulse duration was varied to investigate when removal tends to occur during the discharge. The removal volume became significantly larger at the end of the discharge. The reason for this is thought to be that the recoil pressure increases at the end of the discharge when the discharge current becomes large, and the molten area is easily removed as indicated by the analysis results.
