微细电火花加工技术

本文介绍了微细电火花加工技术的研究开发现状,讨论了传统的电火花加工、线放电磨削加工等微细加工的方法及其应用。     

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。     

大面积微细结构的电火花高效加工

采用深度光刻与电铸技术相结合较好地解决了大深宽比的电火花工具电极的制造问题。在此基础上,利用优化的微细电火花加工工艺,可以实现大面积微细结构的高效、精细制造。     

基于LIGA技术的微细电火花加工

随着众多消费产品向“轻、薄、短、小”方向的发展,微细加工技术日益成为新产品研发中的最重要组成之一,基于微细加工技术的微型机电系统(MEMS)已经成为众多研究机构和企业竞相投资的热门领域之一,其产品遍布工业、农业、医疗、     

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。     

微细电火花加工及应用

随着许多工业及民用设备的小型化,日益需要进行微细复杂形状的高精度加工,特别是对高密度、高深径比形状的模具进行高精度加工更为需要。为满足这方在要求,目前国外研究开发了一种微细电火花加工技术、在穿孔加工中已能够加工出直径5μm的微孔。 过去,对微小复杂形状的电火花加工采用的方法是:使用简单的棒状电极,类似铣削的加工方式,并采用对电极损耗进行补偿或在低损耗状态下进行加工的     

复杂微细形状高技术模具的高速、高品位微细电火花加工技术的开发

无绳电话(手机)、个人信息终端(PDA)以及数码相机等信息通讯设备类,要求小型、重量轻,其内部零件也正在向轻薄短小化发展,模具制造已超出了机械加工的界限,而对电火化加工的依赖性也在迅速提高.     

微细电火花加工中微细电极的制作与检测技术研究

分析了微细电火花加工技术中各种微细电极制作方法的特点,提出了一种加工效率与尺寸精度相兼顾的微细电极在线制作方法.充分利用微细电火花加工机床的数控和接触感知功能,探索并提出了一种微细电极的在线检测方法,并对检测误差进行了分析.实验表明,该方法具有广泛的实用性.     

利用小直径电极的电火花微细轮廓加工

近年来,随着微细加工技术的发展,开发出各种不同的加工方法。有的有希望用来制造微型机器和医疗器械用的零件。就亚微米尺寸加工而言,目前,虽然溅射和蚀剂等加工方法在半导体制造方面占主流,但不适于复杂3维形状的加工。在此之前,电火花微孔加工已显示出高精度加工的效果。以往还曾利用圆柱形电极在低损耗条件下进行过轮廓加工。然而,当采用微小直径电极加工时,由于电极损耗大幅度增加,使电极瑞部棱角产生圆弧R,因而不能实现高精度加工。与上述情况相比,日本三菱公司却积极地利用电极损耗来保持加工底面的棱角,以谋求实现高精度微细形状的加工。一、简单电极轮廓加工原理微细轮廓电火花加工,主要采用微小直径的管状电极,使其在旋转状态下进行加工,以实现所要求的加工轮廓(图1)。在以往,主要是借助于圆柱状电极的侧面来进行轮廓加工见,如图2(a)所示,而微细轮廓加工则利用电极的底面,边反     

微细电火花加工机理研究

通过设计单脉冲放电实验,获得加工材料的表面形貌,以及单脉冲放电形成的凹坑.根据不同参数下材料的表面形貌,分析主要电参数与加工表面粗糙度的关系,以及加工表面凹坑的形成原因,得到影响加工质量的主要参数.     

材料晶界和晶粒对电火花微细加工的影响研究

为了在电火花微细加工中确定合理的工具损耗补偿工艺与加工工艺,提高微小零件微细加工的质量,通过在合金材料上选择晶粒和晶界部位大量加工微孔以及其后的统计分析,研究了微细电火花加工过程中工件材料晶粒与晶界对放电间隙、材料去除速度以及电极体积相对损耗等加工特性的影响。研究结果表明,由于工件材料中晶粒和晶界在成分、熔点、热导率以及机械性能等方面的差异,当用微细电火花进行微细加工,特别是当加工尺度小于工件材料的晶粒尺寸时,晶粒和晶界的加工特性具有明显差别,制订工具损耗补偿工艺和加工工艺时应该考虑到材料微观结构对加工过程的影响。     

UV-LIGA和微细电火花加工技术组合制作三维金属微结构

为了制作三维金属微结构,研究了UV-LIGA和微细电火花加工技术组合的工艺方法。使用UV-LIGA技术制作了准三维金属微结构,然后,对该微结构进行微细电火花加工制作三维金属微结构。使用提出的方法制作出了局部为梯形凸台和锥形凹槽三维微结构的镍模具,给出了梯形凸台和锥形凹槽的尺寸。分析了微细电火花加工中放电参数对表面粗糙度的影响,在工作电压为65V,标称电容为100pF时得到了Ra为0.08μm的微细电火花加工表面。研究结果表明,使用该方法可实现三维金属微结构的制作;通过减小工作电压和标称电容的方法可降低微细电火花加工的表面粗糙度。     

Experimental research on effects of process parameters on servo scanning 3D micro electrical discharge machining

Servo scanning 3D micro electrical discharge machining (3D SSMEDM) is a novel and effective method in fabricating complex 3D micro structures with high aspect ratio on conducting materials.In 3D SSMEDM process,the axial wear of tool electrode can be compensated automatically by servo-keeping discharge gap,instead of the traditional methods that depend on experiential models or intermittent compensation.However,the effects of process parameters on 3D SSMEDM have not been reported up until now.In this study,the emphasis is laid on the effects of pulse duration,peak current,machining polarity,track style,track overlap,and scanning velocity on the 3D SSMEDM performances of machining efficiency,processing status,and surface accuracy.A series of experiments were carried out by machining a micro-rectangle cavity (900 μm×600 μm) on doped silicon.The experimental results were obtained as follows.Peak current plays a main role in machining efficiency and surface accuracy.Pulse duration affects obviously the stability of discharge state.The material removal rate of cathode processing is about 3/5 of that of anode processing.Compared with direction-parallel path,contour-parallel path is better in counteracting the lateral wear of tool electrode end.Scanning velocity should be selected moderately to avoid electric arc and short.Track overlap should be slightly less than the radius of tool electrode.In addition,a typical 3D micro structure of eye shape was machined based on the optimized process parameters.These results are beneficial to improve machining stability,accuracy,and efficiency in 3D SSMEDM.     

Characterization and geometric modeling of single and overlapping craters in micro-EDM

In the micro-electro discharge machining (micro-EDM) process the machined surface consists of tiny overlapping craters. The shape of the crater has significant influence on the characteristics of the machined surface. However, existing models on crater shapes generally do not represent characteristic features of the craters, such as the bulging rim around the crater and the asymmetrical bowl-shape. In this study, experiments were conducted to examine three-dimensional (3D) geometrical features of craters in micro-EDM. Based on the experimental data, a geometric model of craters is proposed to better represent and understand the 3D shapes of single craters. A uniform model and a more realistic nonuniform model of crater geometry are developed, taking into account the bulging rim and the asymmetrical shape in craters. Furthermore, a method of constructing overlapping craters using nonuniform models of single craters is proposed and presented. This method is capable of representing major geometrical features of actual crater clusters.     

Increasing discharge energy of micro-EDM with electrostatic induction feeding method through resonance in circuit

This paper describes the method to increase discharge energy in micro-EDM using electrostatic induction feeding as the pulse generator. In a previous study, controlled pulse train method was introduced to increase discharge energy and enlarge unit removal per discharge by allowing multiple discharges to occur at the same spot. During observation, it was found that the oscillation of discharge current is excited at higher amplitude even if the same capacitance is used. In this paper, the influence of frequency on discharge energy was investigated. It was found that higher discharge energy can be obtained when machining was done at the resonant frequency of the circuit. Influence of capacitance and inductance on resonant frequency was studied. Probability of discharge continuity at different frequencies was examined. The results confirmed that higher discharge continuity within the pre-determined pulse train duration can be achieved when machining is conducted at resonant frequency, leading to higher material removal rate (MRR).     

两种超声加工与放电加工的复合加工方法研究

以比较两种复合加工方法为主要目的,在实验的基础上对两种超声加工和放电加工的复合加工方法进行了研究。     

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.     

Development of Optimum Electrodischarge Machining Technology for Advanced Ceramics

In recent years, ceramic materials with improved properties have been developed to meet a large number of industrial applications. However, in most cases, the cost of the ceramic components is very high. On some occasions, the final machining of the component (especially if complex geometries are to be obtained) accounts for an important percentage of the final cost. The electrodischarge machining process can be a good choice if the material has at least a minimum electrical conductivity, since it can produce very complex shapes and it is not dependent on the hardness or abrasiveness of the material itself. In this paper, the development of sinking and wire electrodischarge machining technology for two ceramics with a promising future (boron carbide and silicon infiltrated silicon carbide) is described. The high removal rates, as well as the possibility of obtaining an excellent surface finish, prove the feasibility of the industrial application of this production method.     

电火花线切割技术发展动态分析

随着机械行业的飞速发展,对各类电火花线切割机床的需求量不断提高,市场竞争日趋激烈.这种形势刺激了相关厂商加大对相关技术的研究力度,促进了对电火花线切割机床性能及功能的提升,实现了电火花线切割技术的进一步发展.     

空气中微细电火花沉积与去除可逆加工技术研究

论述了一种新的电火花加工方法。它使用通用的电火花成形加工机床,利用常见的电极材料,在空气介质中,通过脉冲放电在工件表面上沉积生长电极材料,再通过反转极性和适当的轨迹控制对所生成的沉积材料进行有选择的去除加工,进而实现材料的生长与去除可逆加工。通过对电火花加工理论的研究,预测和论证了实现这一新加工方法的可能性和实现条件。通过试验成功地将钢、铜和钨三种电极材料沉积到工件上,形成直径为 100~240 mm、高度为1 000~2 500 mm的微小圆柱体。并对沉积物进行了选择去除,实现了在同一设备上的可逆电火花加工。对沉积材料的致密性、硬度及其与工件的结合强度等进行了系统的分析,表明沉积物组织致密、坚硬,可以满足功能材料的要求。