【作者】 于丽丽；

【导师】 刘永红；

【作者基本信息】 中国石油大学 ， 机械设计及理论， 2007， 博士

【摘要】 非导电工程陶瓷双电极同步伺服放电加工技术是本课题组新近开发出的一种新的加工方法,该方法主要是利用两极间火花放电通道的能量进行蚀除加工的,它具有生产率高、成本低、对环境无污染等优点。由于该种加工技术的材料蚀除机理复杂,其能量利用方式不同于通常的电火花加工,采用通常的电火花加工理论难以解释其放电蚀除的本质,因此,开展非导电工程陶瓷双电极同步伺服电火花加工机理的研究工作具有重要的理论意义和工程应用价值。本文采用理论分析与实验研究相结合的方法,开展了非导电工程陶瓷双电极同步伺服电火花加工机理及应用技术的研究工作,在放电通道形成、能量分配及其温度场分布等方面取得了一些创新性的研究成果。在电火花加工领域率先采用粒子模拟与蒙特卡罗相结合的方法研究了放电通道的形成机理,建立了非导电工程陶瓷双电极同步伺服电火花加工放电电离过程的模型,仿真了放电通道的微观形成过程,得到了放电过程中电子与离子的空间分布及运动状态。建立了非导电工程陶瓷双电极同步伺服电火花加工基于热传导理论的温度场模型,对陶瓷工件和正、负电极上的温度场进行了三维数值模拟,给出了脉冲宽度、放电电流对非导电工程陶瓷上温度场分布的影响关系。首次系统地研究了放电通道流经非导电工程陶瓷表面时的蚀除机理,在所研制的单脉冲放电及自动检测装置上,对不同脉冲宽度、放电电流和工作介质条件下陶瓷工件和正、负电极的放电蚀除特性进行了实验研究,得到了单脉冲放电坑深度和宽度的经验计算公式,建立了放电能量在工程陶瓷和正、负电极之间的分配模型。针对目前常见的电火花加工神经网络预测模型存在收敛速度慢、易陷于局部极小值等缺点,采用基于混合遗传学习算法的小波网络模型开发了非导电工程陶瓷双电极同步伺服电火花加工工艺效果的预测系统,该系统具有预测速度快、精度高等优点。更多还原

【Abstract】 Electrical discharge machining with synchronous servo double electrodes is a new method developed by us. It removes the materials by spark energy and has the advantages of high efficiency, low costs, environmental pollution-free, and so on. Traditional theory of electrical discharge machining can hardly explain the mechanism of the new technology because of its complicated material erosion and unusual energy partition. For this reason, research on the mechanism and application of the technology has its important theoretical and engineering values.The mechanism and application of electrical discharge machining with synchronous servo double electrodes are studied by means of theoretical analysis combined with experimental research to improve the technology. Some achievements in discharge channel, heat partition, and temperature distribution are obtainedA theoretical and computational model is presented to study the ionization of electrical discharge machining with synchronous servo double electrodes using an electromagnetic particle-in-cell plus Monte Carlo collision method. Forming process of discharge channel is simulated and the detailed information about the distribution of charged particles and electromagnetic fields are obtained.The heat conduction process in non-conductive engineering ceramics and double electrodes is analyzed and a relatively rational model is built. The temperature fields of engineering ceramics, anode electrode and cathode electrode are simulated in 3 dimension and relationship of crater shape and discharge parameters through simulation under different pulse duration and discharge current conditions is analyzed.Experiments of single pulse discharge for electrical discharge machining with synchronous servo double electrodes is designed and some corresponding experiments are done. Effects of parameters such as pulse duration, discharge current and working fluid on material removal of non-conductive engineering ceramic, anode electrode and cathode electrode are discussed. The energy partition among non-conductive engineering ceramics, anode electrodes and cathode electrode is studied through experiments. The results show that energy partition varies little with the increase of pulse duration and discharge current.A model based on wavelet neural network is introduced to predict the process of electrical discharge machining with synchronous servo double electrodes. The simulation system is developed and experiments are carried out to verify the validity of the developed models. The results show that the wavelet neural network model fits the experiments result better.更多还原