微细电解加工实验研究

采用基于电化学腐蚀法制作直径80μm、长度3000μm的微细电极,分别使用微细圆柱电极和微细螺旋电极进行了加工实验,实验研究丧明微细螺旋电极在孔和槽的加工中比微细圆柱电极具有更快的加工速度以及更小的加工间隙.螺旋结构在加工中有助于排出加工间隙内电解产物,显著地提高了加工效率、加工精度及加工过程的稳定性.     

电化学腐蚀法加工微圆柱体

基于电化学腐蚀原理加工微机械加工中使用的微圆柱体,对微细圆柱体成形的机理进行详细的分析。通过对腐蚀过程进行理论建模,利用对电压和腐蚀时间的控制来决定腐蚀后微圆柱体成形的形状以及圆柱体直径尺寸大小。同时,对影响微圆柱体成形的试验参数进行详细的分析,如对电压的控制、电流的变化、电解液浓度的影响、腐蚀时间决定的微圆柱体直径大小等,最后得出微圆柱体成形的规律。理论模型计算结果与试验结果进行比较,证明了理论建模的正确性。利用此种方法试验加工出总长1 180μm,前端较细处长300 μm,直径6μm的钨微细圆柱体结构,长径比达到50:1,并可以在微细加工作为工具电极使用。     

微细电极制备方法研究

微细工具电极在电火花和电解加工中起到关键作用。对微细工具电极的制备方法:反拷法、线电极电火花磨削法以及电化学腐蚀法进行了分析,同时研究了不同方法在异形微细电极制备过程中的应用,在此基础上总结了微细工具电极绝缘层制备方法。通过对电极和绝缘层制备方法的研究,为新式异形工具电极的设计和制备提供技术借鉴,对微细工具电极的结构创新及更高精度的微孔加工具有重要意义。     

微细电解线切割加工的基础研究

基于电化学原理，讨论了纳秒脉冲电流微细电解线切割加工的机理，建立了微细电解线切割加工数学模型；采用电化学腐蚀原理对微米尺度线电极进行在线制作，建立了微细电解线切割加工试验系统，并进行了微细电解线切割加工试验，切割出带90°直角的微结构，其切缝宽度为30μm。     

微米尺度线电极的电化学腐蚀法制备

微细电化学线切割加工是最近出现的一种微细加工新方法。本文基于电化学腐蚀原理,制备微细电化学线切割加工中使用的微米尺度线电极。建立了腐蚀过程理论模型,通过测量线电极的电阻变化来实时监测线电极腐蚀过程中的直径大小,并基于虚拟仪器技术建立了线电极制备监控系统。通过试验对钨线电极的腐蚀过程进行分析,得出监控系统的直径计算值与实际值误差低于10%。最后,利用此方法制备出直径5μm的钨线电极。     

超短脉冲电流微细电解加工技术研究

利用电化学腐蚀方法,在自制的电解加工机床上连续实现微细工具电极的制作和工件的加工,通过试验研究了超短脉冲的电压幅值和脉冲宽度对侧面加工间隙的影响。结果表明,减小脉冲宽度,降低加工电压,可以提高微细电解加工的精度。利用优化的加工参数,进行了微小孔加工、微细直写加工以及成形电极微细加工的实验。     

微细电解线切割加工控制系统

微细电解线切割加工是一种微细加工新方法。本文基于电化学原理,分析了微细电解线切割加工控制系统的要求,利用虚拟仪器设备搭建了加工控制系统,并在Labwindows/CVI软件平台上设计了控制系统软件。本系统通过控制线电极按照DXF图形文件中的轨迹伺服进给,电解腐蚀工件材料达到制造微小零件的目的。试验表明本系统具有稳定可靠、硬件简单、灵活性好等特点。     

微细电化学加工技术

介绍了微软电化学加工的原理及特点，详细介绍了基于电化学扫描探针显微镜进行的电化学微细加工技术，EFAB制作技术、刻蚀剂层技术（GELT）、超微细电极电化学加工技术等几种目前主要的微细电化学加工技术。     

微米级电化学加工关键技术研究

针对微米级电化学加工的关键技术问题，研制了用于微米级电化学加工的纳秒脉冲电源，并利用电化学腐蚀方法，在自制的电化学加工机床上连续实现了微细工具电极的制作和工件的加工。基于试验提出了微细电化学加工间隙的检测控制方法，提高了加工过程的稳定性，增强了定域蚀除能力。在低浓度酸性电解液中实现了微米级的电化学加工，利用研制的纳秒脉冲电源，根据加工电流将极间间隙控制在5μm左右，加工出了“NUAA”字形，每个字母高90μm，宽60μm，字母线条的宽度只有20μm。     

微细电火花加工的发展现状与展望

目前,尽管出现了各种不同的微细加工方法,但由于微细电火花加工法具有独特的优点,因此采用此种方法可以制成各种极微细的高硬度(金刚石烧结体和硬质合金)工具、复杂形状的模具和工件,为此受到业界的普遍关注。     

高回转精度多阶柱状微电极电化学高效制备试验研究

为实现高回转精度多阶柱状微电极的高效加工,对多阶柱状电极电化学刻蚀过程进行了深入的研究与改进。首先,根据电化学刻蚀理论推导了加工电流对电极直径变化的影响规律;通过试验证明了电极旋转可提高电流变化速率及有效起始电流进而提高加工效率,定性分析了电极旋转对电极回转精度的影响,提出了分阶变转速高效加工高回转精度多阶柱状微电极的方法;通过试验分析了各加工参数(电极转速、加工电压和切断电流)对电极形状及尺寸的影响;最后,在优化后的加工参数下,成功加工得到末端直径小于15μm且同轴度误差在1μm以内的多阶柱状微电极,与常规电化学刻蚀工艺相比,显著提高了加工效率。试验证明旋转电化学刻蚀是一种能够较好地提高微电极加工效率及回转精度的新工艺。     

多阶柱状微电极加工模型及试验研究

为实现微电极的精确控制加工,对微细电极电化学刻蚀制备技术进行深入研究。针对单阶柱状电极的不足,分析多阶柱状微电极的加工原理及制备流程。针对分阶电极加工中的三种刻蚀状况,分析各段的刻蚀变化率,并由此推导出电极尺寸与形状控制函数。通过试验证实刻蚀过程中电流密度的不变性,讨论不同电流密度对电极直径的影响规律。通过试验归纳,建立加工电压、电流密度、浸入深度三者之间对应的函数关系,验证电极直径随时间呈线性变化的正确性。基于上述两组模型函数,建立多阶柱状微电极的加工控制模型,并对某三阶柱状微电极的形状及尺寸进行加工预测,实际加工结果显示,试验值与理论值具有很好的一致性。在加工控制模型的指导下成功制备出一批精度高的多阶柱状微电极。     

Fabrication of multiple electrodes and their application for micro-holes array in ECM

In this study, a two-step composite processing technology combining the EDM process and electrochemical etching is introduced to fabricate a micro-electrodes array. Firstly, rectangular columns measuring 0.2×0.2 mm are machined by the wire-EDM (electrical discharge machining) machine tool, then electrochemical etching is used to erode the microelectrodes array into cylindrical columns. Results show that microelectrodes ranging from hundreds of micrometers to several millimeters could be prepared. Then the machined microelectrodes are used as a cathode tool for electrochemical drilling of micro-hole arrays in electrochemical micromachining (EMM). Furthermore, various parameters affecting the performance of EMM are discussed in detail. Results indicate that the production of EMM improves by using multiple microelectrodes. The pulse current shows strong localization in micro-hole drilling and improves the machining accuracy.     

Micro electrochemical milling of complex structures by using in situ fabricated cylindrical electrode

A micro electrochemical milling by layer process is presented in this paper. Because of no tool wear in electrochemical micromachining, a very thin tungsten electrode is used as the tool cathode. By applying ultrashort pulses, dissolution of a workpiece can be restricted to the region very close to the electrode. First, the mathematical model of micro electrochemical milling by layer is established to ensure a good shape precision. Second, the micrometer scale cylindrical electrode is fabricated in situ by electrochemical etching for the production of micro structures. And then, effects of machining parameters on the side gap variation in electrochemical milling process have been studied experimentally. Finally, some 2D micro shapes and 3D complex micro structures with physical dimension of several 10?μm have been obtained.     

Two-step controllable electrochemical etching of tungsten scanning probe microscopy tips

Dynamic electrochemical etching technique is optimized to produce tungsten tips with controllable shape and radius of curvature of less than 10 nm. Nascent features such as "dynamic electrochemical etching" and reverse biasing after "drop-off" are utilized, and "two-step dynamic electrochemical etching" is introduced to produce extremely sharp tips with controllable aspect ratio. Electronic current shut-off time for conventional dc "drop-off" technique is reduced to ～36 ns using high speed analog electronics. Undesirable variability in tip shape, which is innate to static dc electrochemical etching, is mitigated with novel "dynamic electrochemical etching." Overall, we present a facile and robust approach, whereby using a novel etchant level adjustment mechanism, 30° variability in cone angle and 1.5 mm controllability in cone length were achieved, while routinely producing ultra-sharp probes.     

Comparison of different laser-assisted electrochemical methods based on surface morphology characteristics

This paper presents two different laser electrochemical machining (LECM) methods: point-by-point method and scan method. Experiments about the two LECM methods were performed on the aluminum alloy plates placed in a shallow container filled with NaNO₃ electrolyte 2 mm above. Then, the scanning electron microscopy and the optical profiling system were used to analyze machining quality and morphology characteristics of two different machining methods. For the point-by-point method, the shape accuracy at the starting point, finishing point, and node of line cross is lower. Compared with the point-by-point method, the better etching morphology was gained by the scan method in the experiments. The influence of the scan speed on machining quality and groove width was investigated. The better etching surface quality and the higher etching efficiency were gained when the scan speed varied from 0.1 to 0.15 mm/s. These results demonstrate that laser electrochemical machining by the scan method is a promising method to achieve complex profiles.     

准分子激光脉冲直写刻蚀速率与能量密度的关系

为了探索低成本、大深宽比加工方法,建立了实用的准分子激光微加工系统.以玻璃为实验靶材,用精密微动平台准确调节靶材位置,利用波长248nm的KrF准分子激光器,研究了准分子激光直写刻蚀过程中平均刻蚀速率与激光脉冲能量密度之间的关系.加工出的沟槽剖面形状均呈现锥型,单脉冲烧蚀速率随脉冲数的增加而减小,激光脉冲对材料的刻蚀具有能量阈值,加工槽的深度具有上限值.采用平行激光束或对加工过程进行动态控制还可实现矩形深槽或圆柱深孔的加工.     

High-aspect ratio micro-pin manufacturing using inverse slab electrical discharge milling (ISEDM) process

Manufacturing of micro-pins with diameter less than 1 mm is a field of great interest both in research and in industrial application. There is a wide variety of components of low-diameter cylindrical geometry for various applications, including precision products such as gear shafts, valves, shafts, and channels of micro-fluidic systems, parts for micro-pumps and turbines, etc. Increasing interest can also be found in the manufacturing of micro-electrodes for micro-hole EDM drilling of Ti- and Ni-base alloys for the aerospace industry. The inverse slab electrical discharge milling (ISEDM) process has been recently proposed as an economical alternative for the manufacturing of high-aspect ratio low-diameter cylindrical parts. However, application of the process requires understanding the influence of the process variables. The technological data given by conventional SEDM machines (static workpiece) are not valid for this process due to the relative rotation movement of the part with respect to the electrode. In this work, a systematic study of the influence of the process variables on the efficiency of the ISEDM process is presented. The geometrical characteristics of the cylindrical part, its rotational speed, and the energy of the discharge have been included in the study as main input variables. Their effect on material removal rate, surface finish, and micropin accuracy is discussed. Results show that micropins of aspect ratio as high as 90:1 and 0.2 mm diameter can be economically manufactured.     

Ni-Cr-B-Si 系自熔合金激光熔覆层的组成相及其识别方法

本文研究了在通常功率密度下激光熔覆的Ni-Cr-B-Si系自熔合金覆层的组成相及其电化学和化学浸蚀行为,获得了可对此类合金微细、复杂的激光熔覆组织进行精细结构分析的相识别法.