Abstract 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.

中文翻译：

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使用管状电极对高纵横比窄槽进行电化学铣削

摘要 具有高纵横比的金属窄槽，在此称为深窄槽（DNG），广泛应用于精密仪器、医疗器械等行业。然而，由于 DNG 通常小于 4 mm，深宽比（纵横比）大于 2，因此对其进行高精度和高效率的加工仍然极具挑战性，特别是对于盲（即封闭端）外壳。因此，本文提出了一种使用管电极通过单程铣削制造 DNG 的电化学铣削新方法。建立了包括气液两相流场和电场的多物理场耦合模型，研究了不同电解液下电极间隙的流场分布和DNG边缘的电流密度分布压力。还进行了相关实验。模拟和实验结果表明，较高的压力与较高的电解液速度有关，并对加工过程产生显着影响。首先，电极间间隙中的高电解质速度可以增强传质并改善 DNG 的截面轮廓。其次，当电解液流出时，较高的电解液速度可以克服自重力并减少DNG边缘的堆积，从而降低DNG边缘两相流场中电解液的体积分数。因此，出口边缘的电流密度分布降低，DNG 边缘的拐角半径减小。然后，对不同的加工参数（包括电解液压力、脉冲参数和进料速度）研究它们对 DNG 尺寸的影响；优化参数为电解液压力为0.9 MPa，施加电压为12 V，脉冲频率为9 kHz，脉冲占空比为40 %，进料速度为0.36 mm/min，宽度为1.32±0.02 mm的复杂窄槽（平均±标准偏差）和深度8.05±0.01毫米，通过单道铣削加工良好，纵横比达到6.1，显示出高精度和高效的加工方法。