抑气促溶微细电解加工脉冲电源及基础工艺研究

Several outstanding problems occur during electrochemical machining (ECM) of high-aspect-ratio micro holes, such as the contradiction between machining locality and efficiency, difficulties in dissolved matter removal and electrolyte renewal and in precisely detecting on machining gap so on. this study deeply analyzes the process of passive film thickening, explores the mechanism of gas inhibition and dissolution promotion (GIDP) based on adding acid on interface, designs the three-electrode pulse power supply (PPS) with inter-pulse outputs. In this way machining efficiency and surface quality of workpiece are effectively improved without changing the nonlinearity and eco-friendliness of passive electrolyte. By analyzing the change rule of interfacial capacitor with machining gap, the detection method for machining gap based on capacitor of electric double layer (EDL) can be put forward, tries to implement the gap detection by the heterodyne impedance vector method, and seamlessly combines with three-electrode PPS to realize the accurate and rapid online detection on the machining gap. Through studying preparation method of electrode used for micro ECM, a welding preparation process of micro nested hollow electrode (MNHE) is presented, and difficulties in dissolved matter removal and electrolyte renewal will be resolved. Fundamental experiments of micro ECM on micro holes and grooves with high aspect ratio are carried out by utilizing three-electrode PPS and MNHE, which will hopefully solve problems of ECM for high-aspect-ratio allotype holes with variable section whose diameter is 0.1~0.2mm and depth 1.0mm. For promoting the manufacture level of metal precision parts of microstructure, has important practical significance.

为解决高深宽比微结构电解加工中，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，本研究深入分析工件表面钝化膜增厚过程，探讨基于界面加酸的抑气促溶电解加工机理，拟设计具有脉间输出的三电极脉冲电源，在不改变钝性电解液的非线性特征和环保性的同时，有效提高加工效率和表面质量。通过对加工间隙与界面电容变化规律的分析，提出基于界面双电层电容的间隙检测方法，拟完成基于外差式阻抗矢量法的界面电容间隙检测，并与三电极脉冲电源无缝结合，实现加工间隙的快速精密检测。通过微细电极制备方法的研究，提出一种嵌套式微细中空电极的制备工艺，拟解决产物排除与电解液更新困难的问题。采用中空电极和三电极脉冲电源，开展高深宽比微细孔及微细槽电解加工基础工艺研究，有望解决直径0.1~0.2mm、深1.0mm左右变截面孔的精密高效电解加工问题，为提升金属精密零部件微结构的制造水平，具有重要的现实意义。

为解决高深宽比微细孔电解加工中，定域性与效率间的矛盾，产物排除与电解液更新困难等问题，本项目从微细电解加工机理、脉冲电源技术、间隙检测、侧壁绝缘中空电极制备工艺等方面，进行深入研究。.从金属/溶液界面电化学过程分析，粘滞层变厚导致加工电流密度进一步减小，伴生反应析氧量增大，促使钝化膜增更厚，且反应产物组份及表面形貌也各异。通过分析工件表面钝化膜的增厚过程，提出了基于界面酸化过程的抑气促溶电解加工机理。并将抑气促溶机理延伸应用于脉冲电解加工中，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，完成了界面酸化，实现了抑气促溶过程。在不改变钝性电解液的非线性特征和环保的同时，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。.研究侧壁绝缘微细中空电极的制备方法，首先制备出前段加工用内径65μm、外径130μm、长3.5mm左右的嵌套式中空电极。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。其次，提出了一种基于丙烯酸环氧树脂非对称时间双极性电泳法的微细中空电极侧壁绝缘制备新工艺，制备出了表面致密均匀、耐久性好的电极侧壁绝缘层，进而提高了微细电解加工定域性和加工表面质量。.采用上述方法，进行了高深宽比微细孔及微细槽电解加工基础实验。分别加工出直径为175μm左右的、深0.5mm、圆度较高、形状一致性较好的高深宽比微细孔，深1.1mm、锥度1.12度的倒锥孔，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。进而验证了本项目所提方法的有效性，为提升金属精密零部件微结构的制造水平，具有重要的实用价值和现实意义。