微小阵列孔的混粉微细电火花超声复合加工方法及机理研究

Array micro-holes have been widely used in MEMS with its unique functional structure. However, there are issues in micro-electrical discharge machining of array micro-holes such as uneven distribution of flow field and concentration distribution of discharge points, which causes the differences between the inner and outer of holes diameter in the array micro-holes. Therefore, the machining uniformity of array micro-holes has become a difficult problem in the EDM. In order to achieve the machining uniformity of array micro-holes, the method of ultrasonic vibration assisted powder-mixed EDM of array micro-holes is proposed, and the mechanism of ultrasonic vibration assisted powder-mixed EDM of array micro-holes should be fully understood to solve the problems of uneven distribution of flow field and concentration distribution of discharge points. Therefore, the three-dimensional coupled simulation model of flow field and electric field for ultrasonic vibration assisted powder-mixed EDM of array micro-holes is set up to understand the mechanism of EDM of array micro-holes, by numerically simulating the influence of the distribution of flow field and discharge points on the EDM of array micro-holes. In addition, the optics inspection system is established by using transparent materials single crystal silicon carbide in order to observe the distribution of discharge points in EDM of array micro-holes. The effect of the distribution of discharge points on the EDM of array micro-holes is analyzed to verify the correctness of the coupled simulation model. Furthermore, the rules and characteristics of ultrasonic vibration assisted powder-mixed EDM of array micro-holes are explored in order to get the machining uniformity of array micro-holes. The result of this research is of great significance theoretically and practically in enriching the basic theory of EDM and promoting the development and application of micro-EDM technology.

微小阵列孔以其独特的功能结构在微机电系统领域得到广泛应用，但在其电火花加工过程中存在间隙流场分布不均与放电点集中分布等问题，导致阵列内外侧孔孔径加工差异，使微小阵列孔一致性加工成为了微细加工技术难题。针对微小阵列孔一致性加工的技术难题，提出微小阵列孔的混粉微细电火花超声复合加工方法，开展阵列孔加工方法及机理研究，解决加工过程中流场分布不均与放电点集中分布等问题。主要开展阵列孔加工过程的三维流场-电场耦合仿真模型的建立与耦合仿真，研究超声振动作用下间隙流场分布与放电点分布对放电加工的影响，揭示阵列孔电火花加工机理；构建阵列孔加工过程的光学检测系统，研究放电点分布的影响规律及其对放电加工的影响，验证耦合仿真模型的正确性；探索微小阵列孔的混粉微细电火花超声复合加工工艺规律，实现阵列孔的一致性与批量化加工。对丰富电火花加工基础理论、促进微细电火花加工技术的发展与应用具有重要意义和应用价值。

微小阵列孔以独特的功能结构在在航空航天、精密仪器和汽车制造等领域的应用日趋普遍，如航空发动机高压压气机空气导管内阻尼衬套、单晶涡扇叶片气膜孔、化纤喷丝板、喷墨打印机喷嘴和发动机喷油嘴等。微小阵列孔是微机电系统零部件的关键结构，由于核心部件中阵列孔数十微米孔径与阵列孔一致性的加工要求，特别是在核心部件制造中大量采用高硬度、高强度、耐磨和耐热的高性能镍合金和钛合金材料，对微小阵列孔的微细电火花加工技术提出了更高的挑战。针对微小阵列孔孔径一致性的加工需求，系统地研究了阵列孔加工中内外侧孔孔径加工差异的影响因素及规律，探索微小阵列孔的混粉微细电火花超声复合加工方法，以实现阵列孔的一致性加工。建立了系列化微小阵列孔电火花超声复合加工过程三维间隙流场仿真模型，数值模拟了系列化微小阵列孔电火花超声复合加工间隙流场分布、压力场分布和电蚀产物排出过程，分析了系列化阵列孔内外侧孔孔径不一致的影响因素，通过分析阵列电极电火花超声复合加工微小阵列孔过程中放电间隙内间隙流场、压力场和电蚀产物分布规律，揭示了系列化阵列孔内外侧孔孔径加工差异的规律性。建立了微细电极电火花反拷加工连续脉冲放电温度场仿真模型，数值模拟了连续脉冲放电下微细电极表面的温度场分布和凹坑体积情况，得到了微细电极表面凹坑的动态形成过程以及凹坑蚀除体积和最高放电温度的变化规律。进行了阵列电极电火花超声复合加工微小阵列孔加工实验，研究了阵列电极电火花超声复合加工微小阵列孔的工艺规律，分析了阵列电极微细电火花加工阵列孔中超声高频振动对加工过程的影响，通过系列化阵列电极电火花超声复合加工微小阵列孔实验得出了阵列孔内外侧孔孔径变化规律，验证了仿真模型的合理性。开展上述研究对丰富电火花加工基础理论、微细电火花加工技术在超精密加工领域的研究与应用具有重要意义。