【作者】 曾伟梁；

【导师】 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， 2008， 博士

【摘要】 微细电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、微细电火花线切割加工、微细电解加工以及超声复合微细加工技术等的研究均已取得大量的研究成果,但其对微细阵列轴、孔的加工研究则处于起步阶段,尤其是各种加工方法之间缺乏有效的组合与集成。因此适时开展针对微细阵列结构的组合电加工技术研究,充分发挥各自的技术优势,形成高效快捷、可操作性强的微细阵列电极阵列孔的组合加工技术具有十分重要的理论与现实意义。本文首先研究了微细电火花加工的基本原理,分析了放电产生的条件,理论上解释了放电点不能及时转移而形成电弧放电,损害工件表面质量的原因。通过研究微细电火花加工的反拷原理,提出了微细阵列电极的电火花超声复合反拷加工方法,并规划了加工工艺过程。从理论上详细分析了电火花反拷加工分层去除不均匀性的产生因素。为适应大规模阵列电极的加工要求,研究了微细阵列电极的线切割工艺方法。基于电解加工中阴极无损耗的优点,研究了微细阵列孔的电解加工方法。进而提出了微细阵列电极阵列孔的电火花/电解组合加工工艺。从理论上分析了超声空化发生的条件,探讨了自由气泡由于壁面液体压力满足空化初生条件而发生爆炸性成长的过程,计算了空化泡破裂时产生的巨大作用力,说明了超声空化的冲蚀作用。系统地研究了超声振动在微细电火花超声复合加工中的作用机理,说明了在微细阵列电极、阵列孔的电火花加工中复合超声频振动有利于提高加工稳定性和加工效率以及改善加工表面质量的原因。研究了微细电火花加工用微能脉冲电源的设计与实现,分析了微能脉冲电源的实现途径,对高频窄脉宽脉冲电源的设计实现进行了较为深入的研究,设计了分频电路,实现了高品质纳秒级脉冲电源。同时在微细电化学加工中提出采用双路场效应管对脉冲电源进行改进,消除了脉间维持电压,使输出电流更能符合微细电化学加工的需要,改善了加工能力和表面质量。研究了超声波发生器的工作原理,设计了超声波放大器驱动电路,通过对换能器参数的设计计算,实现了超声换能器的串联调谐。针对微细电火花加工中单个脉冲放电能量小,放电状态复杂且变化快等特点,设计间隙电压与充电电流双参数检测法,通过电压信号和电流信号互补消除状态检测的不确定性,确定采样点的放电状态,提高了间隙状态的判断准确性。设计了放电状态检测卡,在硬件上实现了间隙电压与充电电流双参数检测法。研究了RC脉冲放电的特点,根据充电常数,划分了高中低三个档次的门槛电压和电流值,通过对间隙电压和充电电流值的双参数检测来判断极间放电状态,避免了仅凭间隙电压值判断的片面性,提高极间放电状态判断的准确性。根据微细电火花脉冲放电频率远高于运动机构响应频率的特点,以各种相对放电率的统计规律作为控制系统的输入,将模糊控制技术应用到微细电火花加工中,根据相对放电率与正常放电率的误差和误差变化,结合微细电火花人工操作控制经验设计了模糊控制规则,建立了模糊控制查询表,在控制系统中实现了模糊控制算法实验。结果证明,当处于低电压和小电流的微细电火花加工时,采用双参数检测模糊控制后,有效放电增多,脉冲利用率提高,从而提高了加工效率,同时减小了电极的相对损耗率。在电火花反拷加工中,采用正交试验方法分析了加工电压、回路电容、阵列电极间距和振动振幅等工艺参数对阵列电极制作的加工效率的影响规律。在理论分析和试验研究的基础上,加工出了5×5的直径约为Φ30μm的阵列电极,并用此阵列电极加工出了5×5直径约为Φ40μm阵列孔。通过对阵列电极加工阵列孔加工效率和单电极加工阵列孔的加工效率的比较,得出了用阵列电极加工比用单电极加工具有更高的加工效率的结论。对微细阵列电极阵列孔的电火花/电解组合加工工艺进行了分析和研究。用微细电火花线切割加工机床加工出10×10系列方形阵列电极,单电极边长在30μm以下,中心间距为70μm,长0.6mm,表面质量较好。通过微细阵列电极电解加工微细阵列孔,在加工过程中采用适度循环流动工作液方法很好的解决了排屑和加工区温度过高等等难题,获得了质量较好的、大小约为100μm的阵列孔。从而实现了大规模微细阵列电极阵列孔的电火花/电解组合加工,为大规模微细阵列电极阵列孔的加工开辟了高效可行的新工艺方法。更多还原

【Abstract】 Micro electro machining 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 electro-discharge machining (EDM), micro wire electro-discharge machining (WEDM), electrochemical micromachining (EMM) and ultrasonic vibration enhanced machining (UVEM) have got abundance research production, but research on microelectrode array and micro-hole array is on initial phase, especially combination and integration are lacked between these machining methods. Therefore, making study on micro-structure array by conbination micro electro machining methods has very important theoretical and realistic significance.Based on the mechanism of micro-EDM, micro-hole array discharges to fabricate microelectrode array by reverse copying and technology process is planned. Analyze inducing reasons of asymmetry in slicing remove of reverse copying micro-EDM. Made research on WEDM method of microelectrode array fabrication for satisfying large-scale machining require. Made research on EMM method of micro-hole array fabrication based on advantage of cathode without wear. Moreover put forward combined EDM and EMM technology of microelectrode array and micro-hole array fabrication.Analyse ultrasonic cavitate generation condition in theory, calculate huge acting force when cavitating bubble breaking and explain erosion effect of ultrasonic cavitation. Made research on operation mechanism of ultrasonic vibration in micro-EDM systematically, explain reasons of ultrasonic enhanced technology to increase machining stability, work efficiency and surface quality.On the basis of analyzing the realization approaches of micro-energy pulse generator, a set of micro-energy pulse generator is designed. This generator includes RC generator and independent pulse generator. At the same time, put forwards to dual controling MOSFET electrocircuit to improve pulse generator, remove the maintaining voltage and reform working ability and surface quality. Driving electrocircuit of ultrasonic amplifier is designed, parameters are computed in transducer and series tuning is realized. Double parameters detection mode of clearance voltage and charge current is designed due to micro discharge energy, complex discharge state and fast change. Discharge state detection card is designed and realized in hardware.Based on characters of RC pulse discharge, three threshold voltage and current value of high, medium, low is devided according to charge constant. For discharge energy and clearance is very small, discharge state is much complex and changes very fast, traditional detection of average voltage can’t judge discharge state in real time. So detection of clearance voltage and charge current is put forward, value of clearance voltage and charge current are classified by fuzzy theory, then control movement of servo mechanism. According to manual operation control experiencs of micro-EDM, fuzzy control rules is designed and fuzzy query tabulation is set up. When micro-EDM is in condition of low working voltage and small current, fuzzy control system with double parameters detection is proved to improve utilization ratio of pulse, so as to increase utilization ratio, increase working speed and reduce wear ratio of electrode.In the process of machining, influence regularity of four parameters to work efficiency, such as working voltage, working capacity, ultrasonic amplitude and holes spacing, are study by orthogonal experimental technique. 5×5Φ30μm arrays of microelectrode are got and 5×5Φ40μm arrays of micro-hole fabricated by these microelectrode arrays are got. Working efficiency of using microelectrode array and single electrode to machine micro-hole array by Micro-EDM is compared, the former has higher efficiency. Made research on conbination method of WEDM and EMM for microelectrode array and microhole array fabrication. 10×10 arrays of square microelectrode are got by WEDM, length of side is 35μm. 10×10Φ100μm arrays of micro-hole are got by EMM, phenomena of bubble accumulation and high temperature are reduced much more and better quality is got. New technology of large scale microelectrode array and micro-hole array fabricated by combined WEDM and EMM is proved to be feasible and high efficient.更多还原