Abstract The difficulties in circulating working fluid and expelling discharge debris are major challenges for microhole machining by micro electrical discharge machining (micro-EDM). To solve this issue, a novel micro-EDM method that adopts ultrasonic circular vibration (UCV) electrode was proposed in this study, aiming at effectively improving the microhole machining performances. A piezoelectric device for UCV electrode with 32.85 kHz frequency and 3 μm trajectory radius was developed and its basic principle was analyzed. To better understand the effect of UCV electrode on microhole machining process, the solid-liquid two-phase flow simulation was conducted, and the flow field distribution and discharge debris movement in machining gap were studied. Machining experiments of deep microhole (aspect ratio = 9.4) showed that the UCV electrode can effectively lower the electrode retreat frequency and prevent the debris adhesion at the inner wall. 10 × 10 microhole array machining experiments were also carried out in this study. Results showed that the inlet and outlet of microhole array have better morphologies when using UCV electrode, and the diameter consistency of inlet and outlet were improved by 22% and 2.8% compared with rotating electrode. The advantages of UCV electrode in improve microhle machining performances can be mainly attributed to the significantly enlarged flow velocity of working fluid and enhanced capacity of working fluid to expel debris particles in terms of number and efficiency. Meanwhile, the increased relative velocity between electrode and workpiece is also effective to discontinue the abnormal discharges and achieve stable machining process.

中文翻译：

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一种使用超声波圆振动 (UCV) 电极提高微孔加工性能的新型微电火花加工方法

摘要 工作液循环困难和放电碎屑排出困难是微电火花加工（micro-EDM）微孔加工面临的主要挑战。为了解决这个问题，本研究提出了一种采用超声波圆振动（UCV）电极的新型微电火花加工方法，旨在有效提高微孔加工性能。研制了一种频率为32.85 kHz、轨迹半径为3 μm的UCV电极压电装置，并对其基本原理进行了分析。为更好地了解UCV电极对微孔加工过程的影响，进行了固液两相流模拟，研究了加工间隙的流场分布和放电碎屑运动。深微孔加工实验（纵横比=9. 4)表明UCV电极可以有效降低电极后退频率，防止内壁碎屑粘附。本研究还进行了 10 × 10 微孔阵列加工实验。结果表明，使用UCV电极时微孔阵列的入口和出口具有更好的形貌，入口和出口的直径一致性比旋转电极提高了22%和2.8%。UCV电极在提高微孔加工性能方面的优势主要归因于工作流体流速的显着增大和工作流体在数量和效率方面排出碎屑颗粒的能力增强。同时，