长电极多自由度可控磁悬浮伺服驱动微细电火花加工技术

In the micro-EDM,electrode(spindle) servo response frequency is low,and real-time tracking is not good.No-load and short-circuit occurs frequently in the discharge gap,and the effective discharge ratio is low.Electrode needs frequent raplacement,and processing efficiency is low.According to these problems,a micro-EDM technology based on magnetic levitation servo drive form with multi-freedom control and long electrode,is proposed.The rapid response characteristics of the magnetic levitation is exerted.The long wire electrode is used as the micro-electrode,and after a certain length of electrode wear, it can be extended a certain length through the intermittent compensation unit,so the micro-electrode online production and replacement is eliminated. Through the multi-freedom control of the magnetic levitation and the planetary movement,the micro holes with different diameter,tapered bore,ladder hole,and micro-structure can be machined in high speed.The flow field of the discharge gap is analyzed and the micro-EDM machanism of discharge and ablation based on magnetic levitation form is studied.In this project,a micro-EDM experimental device based on magnetic levitation servo drive form with multi-freedom control,is developed.Through the experiment,the influnce of the magnetic system and discharge parameters on the micro-EDM,is studied.The control system is optimized,and the processing rules are summarized.Through the above works, an effective processing method of micro-structure is provided to improve our nation's level of the micro-EDM.

针对微细电火花加工中电极（主轴）伺服响应频率低、实时跟踪性差，放电间隙频繁空载短路，有效放电率低，电极短损耗快需频繁更换，加工效率低问题，提出一种基于多自由度可控磁悬浮伺服驱动的长电极微细电火花加工技术，利用磁悬浮驱动的快速响应特性，用细长电极丝作为微细电极，并使电极损耗一定长度后间歇补偿送进使其伸出长度一定、减少或省去微细电极的在线制作过程和减少电极更换，通过主轴磁悬浮多自由度控制和摇动实现不同孔径微细直孔、锥孔、阶梯孔、微型结构的电火花高速加工。对放电间隙流场进行分析，研究磁悬浮驱动的微细电火花加工放电机理和蚀除机理。研制磁悬浮伺服驱动多自由度可控微细电火花加工试验装置（一轴实现多个方向的运动），进行工艺实验，研究磁悬浮系统、放电参数等对微细电火花加工的影响，优化控制系统，总结加工工艺规律，为微结构加工提供一种有效的加工手段，为其推广使用提供全面技术支持，提高我国微细电火花加工水平。

微细电火花加工过程中，放电间隙小、主轴伺服响应频率低、响应速度慢，导致间隙放电状态复杂多变，正常放电率低，加工质量和加工效率不高。本课题提出并研究了长电极多自由度可控磁悬浮伺服驱动微细电火花加工技术，提高了微细电火花加工主轴伺服响应频率，提高了加工过程中的有效放电率和加工效率。研制了磁悬浮伺服驱动多自由度可控的微细电火花加工主轴，完成了径向磁悬浮轴承和轴向磁悬浮轴承的磁场分布仿真研究。提出并研制了微细电火花加工用微细电极丝夹持定长损耗补偿装置，实现了微细电极丝的夹持和定长补偿。研究了磁悬浮主轴电火花加工控制系统PID控制算法，研制了磁悬浮伺服驱动主轴控制系统，设计了上位机控制系统软件和下位机驱动软件。研制了多模式脉冲电源和基于阈值检测的放电状态检测系统。提出了集磁悬浮伺服驱动控制系统和电火花机床控制系统于一体的宏微复合驱动微细电火花加工技术，实现了高效、高精度宏微复合驱动微细电火花加工技术。进行了磁悬浮伺服驱动微细电火花加工区域流场和温度场仿真，针对TiC/Ni金属陶瓷材料和ZrB2-SiC陶瓷的微细电火花加工，提出了基于硬质相的颗粒随机分布模型，并通过实验进行了验证。根据实验和仿真分析结果提出了TiC/Ni金属陶瓷材料蚀除机理为镍的熔化、气化和碳化钛的熔化、气化、热应力移除。提出了ZrB2-SiC陶瓷电火花加工温度场仿真因ZrB2和SiC熔点不同，在蚀除凹坑轮廓上存在“凹陷点”，同时热裂解的碳、ZrB2和SiC在冷却凝固过程中因热物理参数差别而在电火花加工表面形成了龟裂层。提出了磁悬浮伺服驱动主轴电火花微铣削加工技术，进行了磁悬浮伺服驱动主轴微细电火花微小孔加工和微铣削加工工艺试验，研究了磁悬浮伺服控制系统对微细电火花加工的影响，实现了微小孔、锥孔、阶梯孔、微型结构的电火花高速加工。为微结构加工提供了一种有效的加工手段。