微细电解加工三电极脉冲电源及基础工艺研究

发布时间：2018-06-27 02:26

本文选题：微细电解加工 + 三电极脉冲电源　；参考：《清华大学》2015年博士论文

【摘要】：为解决高深宽比微细孔及微三维结构电解加工中,定域性与效率间的矛盾,产物排除与电解液更新困难,加工间隙难以精密检测等问题,本文从微细电解加工机理、基础工艺及关键技术等方面,进行了深入研究。从金属/溶液界面处电化学反应过程方面,深入研究加工表面电解产物的选择性产生及其去除或减少对微细电解加工的影响规律,通过分析工件表面钝化膜的增厚过程,提出了基于界面加酸过程的抑气促溶微细电解加工机理,在不改变钝性电解液的非线性特征和环保性的同时,有效提高了加工效率和工件表面质量。根据微细电解加工的特征,分析了加工间隙与界面双电层电容的变化规律,提出了基于双电层电容的微细电解加工间隙检测方法。利用工具电极/溶液界面上双电层电容值随加工间隙增大而单调递增的变化关系,精确、快速地实现加工间隙的在线检测,为实现微细加工间隙的精密检测提供了一种新的技术途径。研制了具有脉间输出的三电极高频脉冲电源,利用其辅助电极在加工脉间施加于工件/溶液界面的反向电流,完成了界面加酸,实现了抑气促溶过程。并将抑气促溶机理延伸应用于超短脉冲电解加工中,设计并实现了三电极超短脉冲电源,通过在辅助电极、工具与工件之间,施加同步、等脉宽、等周期、不等幅的负脉冲超短复合电压,完成加工过程,在导出部分阴极气体的同时,蚀除量提高了13%。研究电解加工用微细电极的制备方法,提出了一种嵌套式微细中空电极的制备工艺,制备出前段加工用内径65μm、外径130μm、长3.5mm左右、后段装夹和连通用的嵌套式中空电极。并优化微细中空电极长度,分析了其中的过流特性,确定供液压力。在供液压力为1.15MPa时,出口流速可达10m/s左右,解决了产物排除与电解液更新困难的问题,提高了微细电解加工效率和加工稳定性。采用微细中空电极和三电极脉冲电源,进行了高深宽比微细孔及微细槽电解加工基础实验。优化工艺参数,分别在0.5mm厚的304不锈钢和18CrNi8上,加工出直径为175μm左右的、圆度较高、形状一致性较好的高深宽比阵列微细孔,和宽为160μm左右、深220μm左右的、形状精度及表面质量较高的微细槽。通过高深宽比微细孔及微细糟的电解加工实验表明,采用本研究所提出的基础工艺及方法,在兼顾定域性的同时,有效提高了加工效率、加工精度及表面质量,为探索直径在100μm~200μm、深宽比更大的变截面异形孔电解加工,打下了坚实基础。
[Abstract]:In order to solve the problems such as the contradiction between localization and efficiency, the difficulty of product elimination and electrolyte renewal, and the difficulty of precision detection of machining gap in ECM with high aspect ratio and micro three-dimensional structure, the mechanism of micro-ECM is discussed in this paper. The basic technology and key technology are studied deeply. From the electrochemical reaction process at the metal / solution interface, the selective production of electrolytic products on the machined surface and the influence of the removal or reduction on the micro-ECM are studied in depth. The thickening process of the passivated film on the workpiece surface is analyzed. The mechanism of gas suppression and solubilizing micro-electrolysis machining based on the process of adding acid at the interface is proposed. The machining efficiency and the surface quality of the workpiece are improved effectively without changing the nonlinear characteristics and environmental protection of the blunt electrolyte. According to the characteristics of micro electrolysis machining, the change law of double layer capacitance between machining gap and interface is analyzed, and a method of measuring gap in micro ECM based on double layer capacitance is proposed. Based on the relationship between the capacitance of double electric layer on the tool electrode / solution interface and the increasing of machining gap, the on-line measurement of machining gap is realized accurately and quickly. It provides a new technical approach for the precision detection of micro machining clearance. A three electrode high frequency pulse power supply with interpulse output is developed. The reverse current applied to the workpiece / solution interface by its auxiliary electrode is used to complete the acid addition at the interface and the process of gas suppression and solubilization is realized. The mechanism of gas inhibition and solubilization is extended to ultrashort pulse electrolytic machining, and a three-electrode ultrashort pulse power supply is designed and realized. By applying synchronization, equal pulse width and equal period between auxiliary electrodes, tools and workpieces, a three-electrode ultrashort pulse power supply is designed and realized. The negative pulse ultrashort recombination voltage with different amplitudes completes the machining process and increases the etching amount by 13% while the partial cathode gas is derived. The preparation method of micro electrode for ECM was studied, and a nesting micro hollow electrode was proposed. The inner diameter, external diameter, 3.5mm length, inner diameter and outer diameter of front section were 65 渭 m, 130 渭 m, and about, respectively, and the nesting hollow electrode was fabricated with inner diameter of 65 渭 m and external diameter of 130 渭 m. The length of the micro hollow electrode was optimized and the overcurrent characteristics were analyzed to determine the supply pressure. When the supply pressure is 1.15MPa, the outlet velocity can reach 10m/s, which solves the problem of product elimination and electrolyte renewal, and improves the efficiency and stability of micro-electrolysis machining. The basic experiments of high aspect ratio micro hole and micro groove electrolytic machining were carried out by using micro hollow electrode and three electrode pulse power supply. The optimized process parameters were fabricated on 0.5mm thick 304 stainless steel and 18CrNi8, respectively, with a diameter of about 175 渭 m, high roundness and good shape consistency. The microholes with a width of 160 渭 m and a depth of 220 渭 m were fabricated, respectively. Fine grooves with high shape accuracy and surface quality. The experiments of ECM with fine holes and fine grains at high aspect ratio show that the basic technology and method proposed in this paper can effectively improve the machining efficiency, machining precision and surface quality while giving consideration to localization. A solid foundation has been laid for the exploration of ECM with a diameter of 100 渭 m ~ (200) 渭 m and a larger depth to width ratio.
【学位授予单位】：清华大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TG662

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