二维电火花加工放电位置的电位差法在线检测

研究了电火花加工放电位置的电位差法在线检测,推导了长方体电极下表面上任意点放电的电位差表达式,绘制了电位差与放电位置的关系曲线。在y＝0时的一维情况下与现有试验结果进行了对比研究。     

微细数控电火花仿铣加工电极的在线检测

基于计算机视觉技术,实时地对微细数控电火花仿铣加工电极在线检测。运用微细圆柱形电极图像边缘进行空间矩亚像素定位,直接获得微细电极截面边缘亚像素位置信息,精确计算分辩率截面的微细电极直径,并给出整个微细圆柱形电极直径的实际值。最为有效地对被加工零件与电极的放电间隙及电极损耗补偿规律进行探索与研究。为微细数控电火花仿铣加工电极的放电间隙及电极损耗补偿的预测预报数学模型的建立,获得了电极损耗的可靠数据。     

PS-600/700测试系统校正与放电参数对电极速度的相关性研究

电极向靶运动速度的测量精度和可靠性是研究放电参数与电极运动速度关系的基础.基于实测数据,为日本小野PS-600/700测试系统的加速度计设计校正方法,提出一种准确的经验公式并加以验证,为带电人体手握金属小棒电极,以一定速度向靶放电过程中,电极速度与放电强度参数相关性研究提供了前提条件.研究结果表明,放电电极相互接近的速度与放电电流峰值、放电电流上升斜率峰值具有强正相关性,而与放电弧长则有强负相关性.带电体电压小于300 V时电极速度影响可不考虑.     

非导电工程陶瓷电火花单脉冲放电加工实验研究

提出了一种非导电工程陶瓷电火花磨削新工艺，为了对该工艺的加工机理有更清楚的了解，在非导电工程陶瓷工件表面进行了片电极尖端单脉冲放电的实验，测量了放电间隙大小并分析了其变化规律，给出了放电蚀除坑的形状，研究了各种参数对放电蚀除坑大小的影响关系，根据放电后电极的形状，分析叮放电的极性效应和放电通道的状态。     

微细电火花加工设备技术研究

微细电火花加工的关键设备技术涉及电极的微进给伺服机构、电极和工件的附加树对运动机构、微小能量放电电源以及加工状态检测与控制系统等。文章围绕微细电火花加工系统的设计系统，介绍基于压电致动原理以及摩擦传动的微进给机构、工具电极的线放电磨削机构和旋转主轴、以及微小能量放电电源的设计等，并指出需要进一步研究的课题。     

多信息融合技术驱动的电加工控制优化研究

针对电火花微孔加工放电过程出现畸变,导致检测电路难于获取放电间隙状态的现象,提出了一种采用放电电流和放电电压双特征信息多重检测的方法,基于计算机信息融合技术,完成Matlab模糊神经网络训练模型的构建,提取放电状态特征,得到进行电火花加工电极的伺服控制策略,实验测试结果表明,采用该控制策略方法比某传统单一电路检测控制策略加工效果明显好转,获得相同微小孔深加工时间明显缩短,电极的损耗明显降低。     

放电位置随机分布的电火花线切割加工仿真模型

在电火花线切割单脉冲放电过程仿真的基础上,基于有限元软件ANSYS提出了一种放电位置随机分布的电火花线切割加工温度场仿真模型。在仿真过程中,放电位置随机分布,并引入"生死单元技术"去除高温蚀除的单元,得到了线切割连续脉冲放电加工过程的表面效果。然后利用温度场仿真结果计算不同放电参数下的材料去除率,并基于脉冲利用率和电极丝换向时间进行修正,发现修正后材料去除率仿真结果与实际加工结果之间误差小于10%,验证了电火花线切割加工连续脉冲随机放电的仿真模型的准确性。其中,电火花线切割加工过程的脉冲利用率、电极丝换向时间是导致仿真结果出现偏差的主要因素。为了分析实际加工过程的脉冲利用率,搭建了脉冲利用率检测装置,对不同伺服条件下的脉冲利用率进行了统计。     

多相流多电极弦端电压测量

以电磁感应定律为基础,提出采用多对电极来研究多相流电磁流量计感应电压特性方法,建立了电磁流量计的三维模型,获得了横截面上感应电位的分布规律,分析了电极上的感应电位沿流体管道圆周的分布规律、电极两端的弦端电压与电极对坐标位置的关系、电极电压与电极对所处位置弦长的关系和电极电压与弦长的比值和电极对所处位置的关系.证明多电极测量弦端电压可以用于多相流连续相的速度特性测量与分析.     

数控高效放电铣加工技术

本文介绍了数控高效放电铣加工技术的基本原理。其采用简单超长圆电极，在电极与工件之间施加高效脉冲电源，通过数控系统控制电极与工件的相对运动并对电极损耗进行在线检测和补偿，以类似数控铣的方式加工的特殊材料制作的零件复杂形面，实现对特殊难加工材料的高效、低成本加工。本文还介绍了该加工方法的技术特点、关键技术及应用情况。     

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。     

BCEIA 2005金奖产品金属原位分析仪的研制

本仪器以单次火花放电理论及信号分辨提取技术为基础,自主开发了单次火花放电光谱高速采集技术、单次火花放电光谱数字解析技术、无预燃连续激发同步扫描定位技术.并据此获得数以百万计与材料原位置相对应的各元素原始含量及状态信息.建立了统计偏析度、统计均匀度、统计致密度和夹杂物定量分析数学模型.首次采用统计解析的方法定量表征材料的偏析度、疏松度、夹杂物分布等指标.开创了金属原位统计分布分析新理论、新方法、新技术.并研制成功世界首台金属原位分析仪,实现了金属材料较大尺度范围内各组分的位置分布、状态分布及定量分布的准确信息（即对材料的化学成分、元素分布、偏析度、疏松度以及夹杂物分布的快速准确测定）.具有原始性、原位性及统计性的特点,可作为冶金工艺材料研究及质量判据.     

电火花线切割机床工艺参数优化数据库系统

论述了电火花线切割机床加工过程中电源波形和电参数对工艺指标的影响，以及电极丝对工艺效果的影响，并分析了断丝原因。应用Visual FoxPro6.0建立了“电火花线切割机床工艺参数优化数据库系统”。     

电嘴用半导体的配方和烧成工艺研究

论述了半导体配方和烧成工艺对半导体电嘴电气性能的影响,系统介绍了目前国内外半导体电嘴的发展情况,并通过大量的试验结果,系统地分析了影响半导体电嘴电气性能的各种因素,为合理选择半导体原料和制定产品的烧成工艺提供了理论依据。     

Investigation into erosion rate of AISI 4340 steel during wire electrical discharge turning process

Wire electrical discharge turning (WEDT) process was developed to generate cylindrical form on any electrically conductive material applied in aerospace and automotive industry. The mechanism of metal removal in WEDT process is by means of successive spark discharge. Each spark results in the formation of crater. In the present work, a new model is proposed to predict the erosion rate of each spark for a given discharge energy. A new method is proposed to measure the crater depth from 2D roughness profile of the machined component. The proposed model is validated by conducting experiments on AISI 4340 steel and the results obtained are presented in the paper. It is observed that the results are in close proximity with the experimental values at low discharge energy. The stochastic erosion mechanism of WEDT process is analyzed using scanning electron microscope images of spark eroded wire. Using the proposed model the erosion rate can be controlled and better surface characteristic of machined surface can be achieved.     

An experimental and mathematical study on the effects of ignition energy and system on the flame kernel development

A constant volume combustion chamber is used to investigate the flame kernel development of gasoline air mixtures under various ignition systems, ignition energies and spark plugs. Three kinds of ignition systems are designed and assembled, and the ignition energy is controlled by the variation of the dwell time. Several kinds of spark plugs are also tested. The velocity of flame propagation is measured by a laser deflection method, and the combustion pressure is analyzed by the heat release rate and the mass fraction burnt. The results represent that as the ignition energy is increased by enlarging either dwell time or spark plug gap, the heat release rate and the mass fraction burnt are increased. The electrodes materials and shapes influence the flame kernel development by changing he transfer efficiency of electrical energy to chemical energy. The diameter of electrodes also influences the heat release rate and the burnt mass fraction.     

Electric strength of a vacuum gap during breakdown in an inhomogeneous electric field for switching high-power pulses

A system for matching the output of a multimodular plasma opening switch (POS) to a “liner”-type load having a small initial impedance is described. The main element of this system is an isolating spark gap that allows synchronization of the POS modules and prevents a repeated POS closure cutting off the inductive storage from the load. A spark gap based on a multigap explosive-emission diode, which was proposed and tested earlier, is insufficiently strong electrically to be used in the Baikal project aimed at the development of a superpowerful pulsed generator. An urgent problem of increasing the electrical strength of a 1-mm-wide vacuum gap, which is a basic element of the aforementioned spark gap, is being solved. It is proposed to use electrodes of the point (anode)-plane (cathode) type that allow the electric field to be concentrated at the point-type anode, thereby increasing the gap’s electrical strength. The results of experiments aimed at the study of vacuum breakdown in this system of electrodes are presented. It is shown that this design allows the gap’s strength to be raised by several times, a long service life of electrodes to be ensured thanks to the low energy-deposition density, and a multichannel (i.e., low-inductance) breakdown to be stably attained. A diagram of the spark-gap prototype is presented, its breakdown characteristics are obtained, and a full-scale scheme of the spark gap is presented.     

An experiment of the combustion characteristics with laser-induced spark ignition

The combustion characteristics and minimum ignition energies using laser-induced spark ignition were demonstrated for quiescent methane-air mixtures in an optically-accessible, constant volume combustion chamber. Initial pressure and equivalence ratio as well as spark energy were varied in order to explore the flame behavior with laser-induced spark ignition. Shadowgraphs for the early stages of combustion process showed that the flame kernel becomes separated into two, one of which grows back towards the laser source. Eventually after a short period, the two flame kernels developed into two flame fronts propagating individually, which is unique in laser-induced spark ignition. For a given mixture, lower initial mixture pressure and higher spark energy resulted in shorter flame initiation period and faster flame propagation. The results of minimum ignition energies for laser ignition shows higher values than electric discharge results, however, the difference decreases toward lean and rich flammability limits.     

基于高精度运动平台的误差模型构建与分析

机床误差补偿技术是提高机床精度的一种有效的方法。设计了一个用于微细电火花加工的三维精密运动平台设计,完成了平台搭建工作,根据三维大行程运动平台的几何特性,分析了机床存在的空间定位误差,运用齐次矩阵变换,完成了三维微细电火花加工运动平台的误差补偿理论分析,建立了相应的误差模型。计算机软、硬件技术的发展,误差补偿技术因其性价比高、可靠性好日益受到重视,通过合理的补偿,可使被加工零件的精度得到甚至超过数控加工机床本身的精度。     

Spark plasma sintering of nanostructured powder materials

Spark plasma sintering is a method of consolidating nanostructured powder materials and also composites and gradient materials in the presence of an electromagnetic field, by means of low-voltage sources of powerful current. The main benefit of spark plasma sintering is that previously impossible structures, properties, and compositions may be produced. The finite-element method is used to analyze the consolidation of samples by spark plasma sintering and by a hybrid method in which spark plasma sintering is combined with hot pressing. Corresponding numerical models are tested.