脉动态精密电解加工的方法和理论

This project proposed a new concept of electrochemical machining in the pulse dynamic process. This idea would be helpful for improving the machining accuracy and meeting the urgent demands in aviation, aerospace, and energy industries. Electrochemical machining in the pulse dynamic process is a pulse quasi-equilibrium process, which is different from a continuous equilibrium status in a traditional electrochemical machining process. Electrolysis products accumulation in the machining gap could be reduced and the transient time from the initial machining state to the equilibrium machining state could be minimized. These advantages are beneficial for modeling simulation and achieving precision machining. This project will thoroughly study the proposed electrochemical machining in the pulse dynamic process; develop two innovative methods of copy-like electrochemical machining and counter-rotating electrochemical machining as well as corresponding experimental systems, respectively. These researches will explore the synergistic mechanism of multiple physical coupling for the electrochemical machining. Furthermore, the machining process could be controlled by optimizing the tool motion and the pulse duration at the same frequency or the stagger phase angles. Understanding the evolution laws of the electrochemical machining in the pulse dynamic process is determinative for the work piece shaping prediction and the tool design, which are the basis of electrochemical machining theory. Meanwhile, this project will focus on the key techniques such as coupling adjustment of tool movement and pulse current, protection of side-gap from stray machining and so on. Electrochemical machining in the pulse dynamic process will release the potential of electrochemical machining in precision machining applications. On account of the challenge from the manufacturing of aero-engine blisks and casings, this project will design specialized tools and fixtures on their specific structure features, material characteristics and technical requirements, and carry out experiments. Finally, this project will achieve the precision electrochemical machining of complex components and the profile machining accuracy will reach the leading level of the world.

本项目提出脉动态电解加工新概念，以期显著提高加工精度，满足航空、航天、兵器和能源等工业领域的迫切发展需求。分析认为，脉动态电解加工以脉动态加工和准平衡态取代常规电解加工的连续加工和平衡态，因此将具有产物积累少、过渡过程短、建模精度高等有利于实现高精度加工的特点。本项目将深入系统研究脉动态电解加工过程，创新发展拷贝式和对转式两类脉动态电解加工新方法，建立起这两类脉动态电解加工的试验系统，揭示多场耦合协同作用加工机制，按照同频强化、错位优化等创新思路调控加工过程，掌握过程规律，获取工件成型预测和工具设计方法，建立起脉动态精密电解加工的理论基础，突破耦合调控、侧壁防护等关键技术，充分释放出电解加工在精密加工领域的潜力。结合航空发动机核心部件整体叶盘和机匣的结构特点和技术要求，设计工具和工装，安排脉动态电解加工工艺试验，实现复杂结构件的精密电解加工，型面加工精度达到国际先进水平。

在研制的脉动态电解加工试验系统上，完成了拷贝式和旋印式等多种方式的脉动态电解加工方法和理论研究。通过理论、仿真和试验研究，建立了拷贝式脉动态电解加工多物理场耦合模型、旋印电解加工材料溶解过程及电解液流动状态数学模型、以及旋印电解加工回转体阴极工具设计原则和方法，揭示了镍基高温合金和钛合金材料脉冲电解加工电化学溶解机理、拷贝式加工过程中电场/流场/温度场等多场耦合作用机制以及气泡和焦耳热等产物的输运过程、旋印加工过程中工件材料溶解表面钝化→超钝化演变过程，发现间隙差是引起拷贝式双面加工薄壁工件变形的主导因素、加工间隙在旋印加工过程中呈近似线性缓慢增长趋势、施加反向电流可抑制钛合金氧化膜的产生并消除表面点蚀、线电极机械运动可以产生电场和流场的脉动态变化等科学现象，掌握了脉动态电解加工参数对加工精度和表面质量的影响规律、不同阴极窗口运动轨迹下的凸台轮廓成形规律以及加工间隙内动态流场分布规律、模板电解加工成形过程中超声空化和周期性换向冲液的作用机理及规律。针对航空发动机整体叶盘、大型薄壁机匣等制造难题，提出前置式脉冲振动耦合模式及脉动态电解加工参数优化策略、切向进给前后缘脉动态精密电解加工方法、旋印电解加工回转体阴极工具设计方法、电极旋转状态下复杂变间隙内电解液流场调控策略、以及脉动态电解线切割加工方法，开展工艺试验，实现了典型样件的高精度、高效稳定加工，加工水平达到国际先进水平。.项目研究成果在发展和丰富电解加工理论体系、创新精密和高效电解加工方法、充分释放电解加工潜力等方面具有重要引领作用，在航空发动机等高端制造领域极具应用前景。