Electrochemical milling of narrow grooves with high aspect ratio using a tube electrode
Electrochemical milling of narrow grooves with high aspect ratio using a tube electrode
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使用管电极对高深宽比窄槽进行电化学铣削
DOI：
10.1016/j.jmatprotec.2020.116695
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发表时间：
2020-08-01
影响因子：
6.3
通讯作者：
Zhang, Yongjun
中科院分区：
文献类型：
--
作者：
Zhang, Chuanyun;Yao, Jialu;Zhang, Yongjun
高深宽比金属窄槽在精密仪器、医疗器械等行业中有着广泛的应用。然而，由于DNG的宽度通常小于4 mm，深宽比（纵横比）大于2，因此以高精度和效率加工它们仍然极具挑战性，特别是对于盲板（即，封闭的）案件。因此，本文提出了一种新的电化学铣削的方法，使用一个管电极，通过单程铣削制造DNG。建立了包括气液两相流场和电场在内的多物理场耦合模型，研究了不同电解液压力下电极间隙内的流场分布以及DNG边缘的电流密度分布。并进行了相关实验。模拟和实验结果表明，较高的压力与较高的电解液速度相关联，并对加工过程有显着的影响。首先，电极间隙中的高电解液流速可以增强传质，改善DNG的截面形状。第二，当电解液流出时，较高的电解液流速可以克服自重，减少DNG边缘的积聚，从而降低了DNG边缘两相流场中电解液的体积分数。因此，出口边缘处的电流密度分布减小，并且DNG边缘处的拐角半径减小。在此基础上，对不同的加工参数进行了系统的实验研究（包括电解液压力、脉冲参数和加料速度）对DNG尺寸的影响;在电解液压力为0.9MPa、外加电压为12 V、脉冲频率为9 kHz、脉冲占空比为40%、进给速度为0.36mm/min的条件下，用单道铣削加工出宽度为1.32 ± 0.02 mm（平均值±标准差）、深度为8.05 ± 0.01 mm的复杂窄槽，深宽比达到6.1，显示出高精度和高效率的加工方法。
Metallic narrow grooves with high aspect ratio, referred to here as deep narrow grooves (DNGs), are used widely in precision instruments, medical devices and other industries. However, because DNGs are usually less than 4 mm in width with depth-width ratio (aspect ratio) more than 2, it remains extremely challenging to machine them with high precision and efficiency, especially for blind (i.e., closed-end) cases. Therefore, this paper proposes a novel method of electrochemical milling using a tube electrode to fabricate a DNG by single-pass milling. A multi-physics coupling model, including a gas-liquid two-phase flow field and an electric field, was built to investigate the flow field distribution in the inter-electrode gap as well as the current density distribution at the DNG edge with different electrolyte pressures. Related experiments were also conducted. The simulation and experimental results indicated that a higher pressure was associated with a high electrolyte velocity, and had a significant influence on the machining process. First, the high electrolyte velocity in the inter-electrode gap could enhance the mass transfer and improve the sectional profile of the DNG. Second, when the electrolyte flowed out, the high electrolyte velocity could overcome self-gravity and reduce the accumulation at the edge of the DNG, which decreased the electrolyte volume fraction in the two-phase flow field at the DNG edge. Thus, the current density distribution at the outlet edge was decreased, and the corner radius at the edges of the DNGs was reduced. Then, systematic experiments were performed with different machining parameters (including electrolyte pressure, pulse parameters and feeding speed) to investigate their influence on the DNG dimensions; with the optimized parameters of an electrolyte pressure of 0.9 MPa, applied voltage of 12 V, pulse frequency of 9 kHz, pulse duty cycle of 40 % and feeding speed of 0.36 mm/min, a complex narrow groove of width 1.32 +/- 0.02 mm (mean +/- standard deviation) and depth 8.05 +/- 0.01 mm was well fabricated with single-pass milling, and the aspect ratio reached 6.1, showing a high precision and efficiency machining method.