Pulsed power supply of Tr-RC and Tr-RLC topologies for improvement of micro electrical discharge machining

Pulsed power supply is one of the key technologies in micro-electrical discharge machining (micro-EDM), particularly in machining micro-holes with high aspect ratios. Through the disadvantageous waveform feature analysis of the controllable RC pulsed power supply with random interpulse voltage, insufficient capacitor charging, and uncontrolled reversed fluctuations, an improved Tr-RC pulsed power supply with a promoted function is proposed. Discharge pulses with high power density have the potential to synchronously improve machining efficiency and accuracy. Increasing the discharge peak current by optimizing the pulsed-power topology is a feasible means of improving the power density. A pulsed power supply of the Tr-RLC topology introducing an inductor-controlled branch according to Faraday's law of electromagnetic induction was further proposed based on the improved Tr-RC pulsed power structure. The discharge waveforms of Tr-RLC pulsed power supply achieve an average peak current of 1.3 A with inductance of 20 mu H, compared to 0.5 A with Tr-RC pulsed power supply. For machining micro-holes with aspect ratios of 10:1, 20:1, and 30:1, the Tr-RLC pulsed power supply exhibited an efficiency improvement of 25%, 22%, and 17%, respectively, with reduced taper error and a slight decrease in tool wear rate compared to the Tr-RC pulsed power supply.