金属-陶瓷功能梯度材料的自诱导电火花加工方法及其控制策略研究

Metal-ceramic functionally graded material with its excellent features and innovative design concept has been attracted worldwide attention. But the research on these kinds of materials has been still stayed in the stages of materials design, preparation and performance evaluation in domestic and abroad. Howerver, an effective processing method is essential and indispensable for the emergence of a new material to practical application. A new material processing method and control stratedy based on EDM technology is studied and explored on the premise of full using of the graded material characteristics and processing methods in this project. It is based on the deep study of the metal-ceramic functionally graded materials' physical characteristics, and the metal in ceramic graded material itself is used as the EDM self-induced auxiliary electrode. The EDM basic theory, processing and equipment conditions and the control strategy for the metal-ceramic graded material are studied systematically. The EDM simulation model of the graded material is established. The discharge status during the processing of the metal layer, gradient layer and ceramic layer is analysed. The mechanism of self-induced EDM discharge is determined.The layer-by-layer adaptive fuzzy control strategy and electrode tool lifting strategy is proposed on the basis of the discharge status variation in different machining stages as the excitation source in this project. And the EDM pulsed power is developed based on the machining conditions. The surface property of the EDMed gradient material,such as the generation and distribution of the surface residual stress is revealed.This project will provide a new method for machining the metal-ceramic functionally graded material.

金属-陶瓷功能梯度材料以其优异的特性和新颖的设计理念而备受世人瞩目，其广泛的应用前景令人期待，但目前国内外对该种材料的研究还普遍停留在材料的设计、制备及其性能评价阶段。而一种新材料从出现到实际应用，有效的加工手段是不可或缺的。本项目将在深入研究金属-陶瓷功能梯度材料物理特性的基础上，将材料本身的金属作为陶瓷电火花加工的自诱导源，充分利用材料和加工方法本身的特点，研究和探索一种基于电火花加工技术的新材料加工方法，对其相关基础理论、工艺与装备条件、控制策略等进行系统深入的研究。建立梯度材料持续自诱导的电火花加工仿真模型；研究金属层、梯度层、陶瓷层加工时的放电状态；确定自诱导放电的产生机制；以梯度材料不同加工阶段放电状态的变化作为激发源，提出逐级自适应模糊控制策略和抬刀对策，并研制相应的脉冲电源；对梯度材料电火花加工的残余应力等表层特性进行评定。为金属-陶瓷功能梯度材料的应用提供加工技术支撑。

本项目将金属-陶瓷功能梯度材料的金属层作为陶瓷层电火花加工的自诱导源，探索出一种基于电火花加工技术的新材料自诱导加工方法，并从材料加工特性、仿真模型、去除方式、控制策略和深小孔加工工艺五个方面展开系统研究。以四层Ni-Al2O3功能梯度材料为研究对象，利用提出的自诱导电火花加工方法，成功的实现该材料的加工，并对加工特性及表面质量进行研究分析。通过有限元ANSYS建立材料的仿真模型，分析材料电火花加工过程中的温度场及表面应力场，仿真研究材料去除机理，得出材料去除机理包括熔化、气化和陶瓷颗粒的整体脱落的结论。利用SEM和OLS激光共聚焦分析了加工表面微观形貌、表面元素分布和3D结构，研究表面特性，得出该材料去除方式。研制高能窄脉宽RC电火花电源，通过高能脉冲的控制清除积屑，提高了材料的加工速度的加工深度。针对现有伺服控制的不足和脉冲电源的特点，对伺服进行模糊控制，提高了伺服运动的灵活性和针对性。结合上述的理论和控制策略，对Ni-Al2O3功能梯度材料深小孔加工进行工艺研究，通过单因素工艺试验，实现了深小孔的快速加工。