微细电火花加工机床关键技术

研制开发两台高精度、高性能,具有自主知识产权的微细电火花加工机床,并对微细电火花加工机床的几个特有关键技术进行了深入研究.基于压电陶瓷的宏微伺服进给系统能实现分辨率为3.42 nm的微进给,并且能实现振动式进给,以改善微细电火花加工的间隙状态,提高微细电火花的加工效率和加工质量.结合块电极反拷与线电极反拷的微细工具电极反拷系统,可高效高精度地现场制作微细电极,电极直径最小可达4 μm.基于多传感器信息融合技术的放电间隙状态监测技术,能很好地解决微细电火花加工间隙状态的监测与识别问题.RC脉冲电源不存在维持电压现象,这一最新发现为降低单脉冲放电能量难题提供一个新的解决途径,使得基于RC方法开发的超微能脉冲电源的单脉冲放电能量最小降至皮焦级,为微细电火花加工奠定了良好的基础.最后的微细电火花加工试验表明,所开发的微细电火花加工机床性能稳定,且加工质量良好,尤其适合加工孔径为50～200 μm的微细孔.     

微细电火花加工及其关键技术

综述了微细电火花加工的基本原理及最新研究进展。比较了LIGA技术与微细电火花加工的特点与应用。简要分析了微细电火花加工的关键技术：微细电极的在线制作、微进给装置、微小能量的脉冲电源、微小电极的运动轨迹规划、电极的损耗及补偿策略。展望了微细电火花加工在微三维结构加工中的应用前景。     

一种新型卧式微电火花机床的设计与实验研究

针对微电极制作的效率问题,提出了一种快速在线微电极加工成形的方法,设计了一种新型卧式微电火花机床。该机床由金刚石砂轮超精密在线电极磨削、线电极电火花在线电极磨削共同完成微米级电极的高效精密制作,该机床组成部分还包括基于CCD的在线光学尺寸检测与测量系统、精密运动与进给系统、纳秒级独立式脉冲放电电源与放电状态检测反馈系统组成。在该机床上进行了微电极制作、微小孔加工以及微电火花铣削等实验,加工出直径为15μm微细轴和直径为50μm微小孔。     

电火花微细孔加工电极损耗实验研究

用实验的方法研究电火花微细加工中放电能量在极间的分配和对电极损耗的影响，并研究式具电极材料和工件材料对电极损耗的影响，实验表明，从减小电极损耗，增加有用功率出发，电火花微细加工应使用微能窄脉冲电源。     

民火花微细加工系统研制

根据电火花微细加工的技术特点，设计研制适应电火花微细加工要求的伺服控制系统，微能脉冲电源和微细电极制造机构，整个系统工作稳定，能够较好地达到微细加工的要求。     

基于异形孔等效放电面积的微细电火花加工技术

针对喷丝板异形孔加工这一工艺难题，分析了微细电火花加工系统的关键技术，并对传统晶体管可控式RC脉冲电源电路拓扑进行了改进，设计并研制出适合微细电火花加工的新型微能脉冲电源。针对等效放电面积对微小异形孔加工效率及加工精度的影响进行了详细的理论分析与大量实验研究，为合理地选择加工规准提供了可靠的理论与实践依据。     

采用蠕动式微进给机构的微细电火花加工装置

介绍了一种采用蠕动式微进给机构的微细电火花加工装置，尝试微细火花加工的实用化和装置本身的微小型化。内容包括该装置机构的设计制作及初步的加工实验结果，特别是蠕动式微进给机构提高输出推力、适用于微细电火花加工的设计实现。     

微细电火花线切割加工关键技术

在分析微细电火花线切割加工特点的基础上,对获得高精度、高表面质量工艺指标的关键技术进行了研究。其中重点对微能量脉冲电源、恒张力走丝系统、偏开路伺服控制策略、基于压电陶瓷电动机的微驱动进给系统、智能工艺规划系统和加工工作液间隙特性等关键技术进行了研究,解决了微小复杂零件难以切割的问题,并且获得高质量微小复杂零件,最终满足了微细电火花线切割加工的需要。     

复杂微小零件的微细电火花线切割加工技术研究

在分析微细电火花线切割加工特点的基础上,对获得高精度、高表面质量加工指标的关键技术进行了研究.重点对微能脉冲电源、智能工艺规划系统和加工工作液间隙特性等关键技术进行了研究,解决了微能脉冲电源能量精确可控以及微小复杂零件加工工艺规准的智能决策问题,满足了微细电火花线切割加工的需要.     

高频窄脉冲电流微细电解加工

微细电解加工是微细加工领域很有发展前景的微细加工技术之一。适合于微细电解加工的装置被研制出来, 它包括机床进给机构、线电极电火花磨削在线制作微细电极装置、短路检测模块、脉冲电源及其他一些辅助装置, 其中,高频窄脉冲电源是微细电解加工最重要的核心技术之一。根据微细电解加工的特点,设计了微细电解加工 MOSFET脉冲电源,该微能脉冲电源能很好地满足微细电解加工的要求。运用该微细电解加工装置进行加工试验, 在低的加工电压和低的钝化电解液浓度条件下,利用高速旋转的微细电极加工微小孔和像小铣刀一样进行微细电解铣削加工微结构,得到了满意的工艺效果,因而进一步说明电解加工在微细加工领域很有发展潜力。     

Micro electro discharge machine with an inchworm type of micro feed mechanism

A micro electro discharge machine with an inchworm type of micro feed mechanism has been developed. The prototype of micro electro discharge machine is comprised of a wire electro discharge grinding unit, a rotating unit of electrode, RC circuitry for micro electro discharge generation and a subsystem detecting and controlling machining process, in addition to the inchworm mechanism. In the design of the inchworm mechanism, a novel clamp mechanism with force magnifying structure is devised to increase its thrust capability and a pair of guide sleeves together with the clamps are used to decrease yawing error. The inchworm mechanism prototype has 60 mm stroke only limited by the length of the shaft, less than 2 μm yawing error and reaches to 30N output thrust force. The machining experiments carried out on the micro EDM prototype are also described. The techniques to machine micro electrode, micro holes with high aspect ratio, micro structures on stainless steel and silicon materials are discussed. Micro electrode diameter as small as 25 μm and micro holes with minimum size of less than 50 μm are obtained. And the maximum aspect ratios of micro electrodes and micro holes exceed 20 and 10 respectively.     

RESEARCH OF MICRO ELECTRO DISCHARGE MACHINING EQUIPMENT AND PROCESS TECHNIQUES

Micro electro discharge machining (micro EDM) is a feasible way to manufacture micro structures and has potential application in advanced industrial fields. For the realization of micro EDM, it is necessary to pay careful attention to its equipment design and the development of process techniques. The present status of research and development of micro EDM equipment and process techniques is overviewed. A micro electro discharge machine incorporated with an inchworm type of micro feed mechanism is introduced, and a micro electro discharge machine for drilling micro holes suitable to industrial use is also introduced. Some of the machining experiments carried out on the micro EDM prototypes are shown and the feasibility of the micro EDM technology to practical use is discussed.     

微细球状电极制备研究

微细球状电极在精微加工、测量领域有很大的应用空间,为制备低成本、高精度微细球状电极,提出新的制备工艺,在微细电解加工机床上运用微细电化学刻蚀(Micro electro-chemical machining,micro-ECM)—单脉冲放电加工(One pulseelectro discharge,OPEG)组合技术制...     

Precision machining of micro tool electrodes in micro EDM for drilling array micro holes

Micro electro discharge machining (micro EDM) is suitable for machining micro holes on metal alloy materials, and the micro holes can be machined even to several microns by use of wire electro discharge grinding (WEDG) of micro electrodes. However, considering practicability of micro holes <Φ100 μm in batch processing, the controllable accuracy of holes’ diameter, the consistency accuracy of repeated machining and the processing efficiency are required to be systematically improved. On the basis of conventional WEDG method, a tangential feed WEDG (TF-WEDG) method combined with on-line measurement using a charge coupled device (CCD) was proposed for improving on-line machining accuracy of micro electrodes. In TF-WEDG, removal resolution of micro-electrode diameter (the minimum thickness to be removed from micro electrode) is greatly improved by feeding the electrode along the tangential direction of wire-guide arc, and the resolution is further improved by employing negative polarity machining. Taking advantage of the high removal resolution, the precise diameter of micro-electrode can be achieved by the tangential feed of electrode to a certain position after diameter feedback of on-line measurement. Furthermore, a hybrid process was presented by combining the TF-WEDG method and a self-drilled holes method to improve the machining efficiency of micro electrodes. A cyclic alternating process of micro-electrode repeated machining and micro holes’ drilling was implemented for array micro holes with high consistency accuracy. Micro-EDM experiments were carried out for verifying the proposed methods and processes, and the experimental results show that the repeated machining accuracy of micro electrodes was less than 2 μm and the consistency accuracy of array micro holes was ±1.1 μm.     

微细电火花铣削CAD/CAM方法研究

利用简单电极的微细电火花铣削加工具有适应性强、可操作性好等特点,在微三维结构的制作方面显示出了良好的应用前景。但是在电火花分层铣削加工中,加工表面始终存在着台阶问题,并且对方程难以给定的复杂曲面而言尤为如此。系统研究了微细电火花铣削的分层策略、电极轨迹生成方法、插补算法以及加工轨迹的平滑算法,结合等参数插补方法对分层加工后的型腔表面进行修正,较好地解决了加工台阶问题。利用所研究的CAD/CAM技术进行了加工试验,给出了亚毫米级复杂三维曲面的加工实例,验证了方法的正确性。     

高频窄脉宽微细电火花加工用微能脉冲电源的研究

分析了微能脉冲电源的实现途径。采用开关管推挽工作原理设计出了具有高频窄脉宽的微细电火花加工用微能脉冲电源。并对具有陡上升沿和下降沿的高频脉冲电源工作时产生的电磁振荡现象的原因进行了深入的研究。在此基础上设计出的脉冲电源最小脉宽可达100ns，较好地满足了微细电火花加工的需要。     

微细电火花加工中电极材料的蚀除机理研究

在微细电火花加工过程中 ,由于放电时间极短 ,使得其阴阳两极的电极材料蚀除过程产生较大的差异。本文应用传热学和电场的基本理论 ,分别对微细电火花加工阴阳两极的材料蚀除机理进行了理论研究 ,得出了在窄脉宽微细电火花加工中 ,尽量缩短脉宽可提高阳极材料的去除效率 ,同时又不会明显增加阴极材料损耗的结论。为微细电火花加工脉冲电源设计及加工工艺的改进提供了理论依据     

Development of an unconventional electro-hydraulic proportional valve with fuzzy-logic controller for hydraulic presses

A micro slit die easily manufactured using a micro electrical discharge machining (MEDM) is proposed for micro heat sink fabrication. In the investigations described in this paper, processed concave and rectangular shaped copper foils were combined piece by piece to form an assembled electrode. This electrode was used to fabricate a micro slit die. This die included 15 micro fins in a small tungsten carbide plate. The micro heat sink was made by applying a pressing or scraping method when the micro slit die was used. The experiments showed that debris, produced by the MEDM, might cause a discharge concentration effect because of the narrow gaps between the workpiece and electrode. Parts of the micro fin were seriously melted during this process. Flushing dielectric could effectively remove the debris from the narrow gap, generating an appropriate discharge dispersing effect. However, the discharge effect was unstable when large flushing pressure was applied, thus reducing the machining precision. The micro fins were formed into a rectangular shape using kerosene as the MEDM dielectric. Using distilled water as the MEDM dielectric produced a higher material removal rate and serious assembled electrode wear. Therefore, the micro fins formed as triangle profiles. The micro heat sink was higher even when the pressing method was used. The heat sink deviated and was full of burrs on the fin edge when the scraping method was used.