Effects of stepped cylindrical electrode in electrical discharge machining of blind holes
Effects of stepped cylindrical electrode in electrical discharge machining of blind holes
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DOI：
10.1007/s00170-020-05941-3
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发表时间：
2020-08
期刊：
影响因子：
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通讯作者：
X. Mao;Xiangzhi Wang;Chaojiang Li;J. Mo;S. Ding
中科院分区：
文献类型：
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作者：
X. Mao;Xiangzhi Wang;Chaojiang Li;J. Mo;S. Ding
电火花加工（EDM）是一种非传统的加工方法，已广泛应用于加工难加工材料。然而，电火花加工工艺的效率较低，特别是在加工深盲孔时，由于放电间隙中碎片的去除较差，钻孔质量受到关注。本研究提出了一种基于电极形状修饰的新策略，通过间接改变介质的流动来解决这一问题。采用相同加工面积的5种不同形状电极，提高了加工过程中的碎屑去除率。研究了不同电极形状对加工性能的影响。采用加工时间、材料去除率（MRR）和电极磨损率（EWR）评价加工性能。利用计算流体动力学（CFD）软件Fluent模拟了不同电极轮廓引起的介质流动。结果表明：与直电极相比，弯曲电极和长弯曲电极的最大有效切削深度分别提高了13.793%和132.184%，当工作长度为2mm和4mm的电极加工深度分别达到2 mm和4 mm时，阶梯电极的MRR显著提高。用各种电极加工的孔的表面粗糙度是相同的。而直电极在较低切割深度处碳附着明显，其次是弯曲电极和长弯曲电极。
Electrical discharge machining (EDM) is a non-conventional machining process which has been widely used to machine difficult-to-cut materials. However, the efficiency of EDM hole making processes is low, and the quality of drilled holes is a concern especially when machining deep blind holes due to the poor removal of debris in the discharging gap. In this study, a new strategy based on shape modification of the electrode was developed to address this issue by indirectly changing the flow of dielectric. The electrodes of five different shapes with identical machining area were applied to improve the debris removal during the machining process. The effects of various electrode profiles on the machining performance were investigated. Machine time, material removal rate (MRR) and electrode wear rate (EWR) were used to evaluate the machining performance. The computational fluid dynamic (CFD) software Fluent was used to simulate the flow of dielectric caused by different electrode profiles. The results show that, compared with the straight electrode, the maximum effective cutting depth of curved electrodes and long-curved electrodes increased 13.793% and 132.184%, respectively, and the MRR of stepped electrodes was significantly higher after the machining depth reached 2 mm and 4 mm for electrodes with the working length of 2 mm and 4 mm, respectively. The surface roughness was identical for holes machined by all types of electrode. However, obvious carbon adhesion can be observed at lower cutting depth for straight electrode, followed by curved and long-curved electrodes.