【作者】 李刚；

【导师】 赵万生； 王振龙；

【作者基本信息】 哈尔滨工业大学 ， 机械制造及其自动化， 2007， 博士

【摘要】 微小型化是现代工业产品一个非常重要的发展方向。微细电火花加工技术因其非接触加工、材料适应性广、没有宏观作用力等优点,在微小零件的加工中具有独特的优势。微细电火花加工方法不仅能加工微细轴、微细孔、微细槽等简单结构,还能加工复杂形状的微小三维零件。微细电火花加工技术目前已经成为微细加工领域一个非常重要的研究方向,受到国内外学者的广泛重视。精密的微细电火花加工装备是开展微细电火花加工技术研究的基础。国外微细电火花加工机床已进入工业应用和商业销售阶段,但制造费用仍非常昂贵。国内微细电火花加工装备的研制相对落后,而国外的机床对我国严格禁运。因此,自主研制高性能的微细电火花加工装备和相应的加工工艺具有重大的现实意义。本文首先分析了微细电火花加工的特点及其对加工装备的要求,设计、研制了一套基于直线电机的微细电火花加工系统。该加工系统由机械系统和控制系统两部分组成,机械系统包括直线电机伺服机构、精密旋转主轴、高精度花岗岩机床本体和工作台、微细轴磨削装置等;控制系统包括控制计算机、微能脉冲电源、放电状态检测系统、运动控制器、电机驱动器、CCD机器视觉显微系统等几个部分。伺服机构及其控制系统是微细电火花加工系统的重要组成部分。本文分析对比了多种伺服机构的性能和优缺点,采用了基于直线电机的伺服机构,提出并实现了基于直线电机的伺服控制策略。该伺服系统具有分辨率高、精度高、速度高、响应快等优点,能够有效提高电火花加工的加工效率、降低电极相对损耗率。针对微细电火花分层铣削加工,提出了分层策略、电极运动轨迹规划方法、电极损耗补偿策略等,开发了微细电火花铣削加工专用CAM软件,解决了微细电火花铣削加工中的技术难题。对块电极电火花磨削(Block Electrode Discharge Grinding,简称BEDG)微细轴的方法进行了深入的研究,采用径向进给和轴向进给相结合的方法,加工出直径5μm微细轴。提出了刃口电极电火花磨削(Edge Electrode Discharge Grinding,简称EEDG)微细轴的方法,该方法比线电极磨削(Wire Electrode Discharge Grinding,简称WEDG)方法加工速度快,工艺稳定性好,而且装置简单,操作简单,加工质量好。采用该方法成功地加工出直径3.5μm的微细轴。进行了大量的微细电火花加工工艺实验,系统研究了电参数、主轴转速和工作液类型对加工效率、电极相对损耗率及工件表面粗糙度的影响,得到一系列工艺规律。在微细电火花加工系统上进行了大量的加工实验,成功地加工出直径8μm的微细孔,宽度为15μm的微细槽、微细梁等结构。利用微细电火花铣削加工专用CAM软件生成的数控代码,在微细电火花加工系统上加工出微细齿轮、微细鼠标等微细三维结构,验证了微细电火花加工系统的微三维结构加工能力和CAM软件的正确性、实用性。更多还原

【Abstract】 Miniaturization is one of the most important trends of industrial production. Micro electro-discharge machining (EDM) gives it the ability to machine many difficult-to-cut materials. Its unique advantages of non-contact and less-cutting-force are useful in micro machining field. Micro-EDM is not only applied to machining micro-shafts, micro-holes and micro slots, but also to machining 3D micro structures and micro freeform. Therefore, micro-EDM has become one of the most important branches in the field of micro machining and receives worldwide attention.Precise micro-EDM system is the essential equipment for micro-EDM research. Nowdays, Micro-EDM machines have stepped into the stage of industry application and commercial distribution in some developed countries, whereas, these machines are prohibited goods to our country. Thus, it is urgent for us to develop high performance micro-EDM equipments.Based on the analysis of the features and the requirement of the equipment of micro-EDM, a set of micro-EDM system based on linear motor is developed. It composed of a mechanical system and a control system. The mechanical system consists of a precise granite body and a worktable, a three-dimensional servo mechanism based on linear motor, a precise rotary spindle and a discharge grinding unit, etc. The control system includes a control computer, a RC pulse generator, a discharge detecting circuitry, a motion controller, motor drivers and a CCD microscopic vision system, etc.Servo mechanism and its control system play an important role in micro-EDM system. The properties of many types of servo mechanism are discussed, and linear motor is adopted in the micro-EDM system because of its excellent performance of high resolution, high precision, high speed and quick response. The servo mechanism and control system can improve the machining efficiency and decrease relative electrode wear ratio of micro EDM.As to ED-milling, slicing strategy, arrange method of tool path and method to compensate electrode wear are proposed in this dissertation. A special CAM software package for ED-milling 3D micro structures is developed. Electrode manufacturing technique is the fundamental of micro-EDM, hence is systematically investigated in the dissertation. Micro shaft with a diameter of 5μm is achieved by block electrode discharge grinding (BEDG). A new tool manufacturing method named edge electrode discharge grinding (EEDG) is presented in this dissertation. EEDG is proved to be more effective than WEDG because of its simple structure, low cost, quick setting, high machining efficiency and good surface quality. Micro shaft with a diameter of 3.5μm is manufactured by using this method.Extensive processing experiments have been conducted on this micro EDM system. The effect of electrical parameters, spindle speed and dielectric on machining efficiency, relative electrode wear rate and surface roughness has been systematically investigated, and many micro-EDM machining rules have been achieved. A great number of experiments have been carried out on this micro-EDM system, the results show that micro shaft with a diameter of 3.5μm, micro hole with a diameter of 8μm and micro slot and micro slit with a width of 15μm can be obtained steadily. With the aid of the special CAM software package for ED-milling, 3D micro structures such as micro gear, micro mouse are machined on this micro-EDM system. The micro machining capability of this micro-EDM system and the performance of the CAM software packages are verified by these experiments.更多还原