空间曲面电火花线切割加工运动规律及加工实验研究

为解决空间曲面零件的加工难题,分析空间曲面电火花线切割加工的运动规律,建立电火花线切割极坐标加工系统的数学模型.研制翻转式自动分度数控回转工作台,开发多轴联动线切割加工控制软件,形成空间曲面电火花线切割加工系统.与国产高速走丝电火花线切割机床相结合,加工出理想的空间曲面零件.拓宽了电火花线切割加工的工艺范围,从根本上解决空间曲面零件高速走丝电火花线切割加工的关键技术问题.该方法可广泛应用于模具制造及空间曲面零件加工.     

数控电火花线切割加工在塑料模加工中的应用

分析了数控电火花线切割加工在塑料模加工中的应用场合,探讨了数控电火花线切割加工在塑料模加工应用中的几种特殊方法.     

对往复走丝电火花线切割加工技术发展的思考

对往复走丝电火花线切割加工现有工艺指标——切割速度、表面粗糙度及加工精度进行了探究,为提出新的工艺指标提供有利于往复走丝电火花线切割加工技术发展的依据。介绍了单向走丝电火花线切割加工与往复走丝电火花线切割加工的本质区别,论述了往复走丝电火花线切割加工的生命力及其技术发展的定位。     

数控精密电火花与线切割加工在现代模具加工中的应用

分析了数控精密电火花线切割加工技术及电火花成型加工技术在冲模及型腔模加工中的应用,探讨了电火花与线切割在模具加工应用中的几种特殊加工方法,如电火花线切割、电火花成型以及电火花微细孔机的特殊加工方法。     

零件大角度面电火花线切割加工瓶颈的分析与对策

通过对模具零件大角度面电火花线切割加工瓶颈的研究,找到解决电火花线切割大角度面加工瓶颈的方法,通过制备电火花线切割角度装夹夹具和正弦磁力吸台,解决了模具零件大角度面电火花线切割加工瓶颈的问题,同时也提高了电火花线切割模具零件大角度面的加工效率和质量。     

“中走丝”电火花线切割机床的特点

所谓"中走丝"电火花线切割机床,准确地说应该是具有多次切割功能的高速走丝电火花线切割机床.它的走丝速度为1.5～10 m/s,可以根据需要进行调节.其走丝速度和加工质量介于高速走丝和低速走丝线切割加工之间. "中走丝"电火花线切割加工与传统的高速走丝电火花线切割加工相比,既有继承,又有发展,它具有以下一些特点:     

电火花线切割加工技术及其发展动向

阐述了近年来国内外电火花线切割加工技术的发展动向、电火花线切割加工技术的发展趋势以及我国电火花线切割加工领域亟待发展的关键技术。     

电火花、线切割加工技术系列丛书征订

数控电火花线切割加工技术内容包括 :数控电火花线切割原理 ;电火花线切割机床 ;线切割编程 ;线切割微机编程 ;线切割控制 ;电火花线切割脉冲电源 ;电火花线切割工艺 ;电火花线切割机床的精度检验方法。本书由张学仁教授主编 ,刘晋春教授主审。本书 2 8.4万字 ,每本定价 14.50元 ,2 0 0 0年 2月出书。电火花加工技术讲述电火花加工的原理和机理 ,电火花穿孔、成型加工的机床、脉冲电源、控制系统、工艺规律及各类典型模具和零件的加工实例和要点。本书由赵万生教授主编 ,刘晋春教授主审。本书约 2 8万字 ,每本定价 14.50元 ,2 0 0 0年 5月出…     

基于总线的线切割控制系统

目前高频电火花线切割加工机床大量应用于精密加工中.本文开发了电火花线切割加工机床上位机与下位机CAN总线实时通讯系统,满足加工过程中数据传输的实时性与可靠性.     

电火花线切割技术研究现状及发展趋势

总结近年来电火花线切割技术的发展现状,就现阶段电火花线切割加工中所存在的问题进行分析,同时依据现有的研究成果分析电火花线切割加工的发展趋势。     

基于NX12五轴定位的分流器基座铣削加工工艺设计

为了满足某专业船舶轮机分流器基座的定位精度要求,提出了表面光洁度、垂直度以及尺寸精度等指标。通过对三轴常规加工和五轴定向加工进行变换与分析,运用多工序的加工方法、3+2五轴定向加工方式以及模拟仿真的手段,保证了加工效果。结果表明：五轴定位加工可大大缩短加工时间,提高加工效率,保证各个表面相互位置的精度,该功能已在模具市场得到了广泛应用。     

Tool path planning for five-axis machining using the principal axis method

A study of the effect of feed direction on five-axis tool paths generated using local surface properties for tool orientation and positioning is presented in this paper. The principal axis method for five-axis machining defines the placement of the cutting tool at a single point on the workpiece surface and assumes that a preferred feed direction will be maintained. This preferred direction may not represent a practical choice for tool path planning. In this work, numerical simulations are used to evaluate tool paths with different feed directions. Numerical simulations are then verified experimentally by machining two example surfaces. The results show that both gouging and the effective cutter profile will dictate the optimal choice of feed direction.     

万能升降台铣床对刀仪

加工轴叉万向节面过程中,对刀总是出现较大的误差,使得被加工万向节面出现较大对称度误差,甚至超差。为解决这一问题,综合考虑定位装置及轴叉万向节面加工的特点,参考游标卡尺结构,设计万能升降台铣床对刀仪,并应用于实际加工过程。结果表明:所设计的万能升降台铣床对刀仪可以实现准确、方便、快速的对刀,节省了加工时间,满足了加工质量要求。     

小型反射面板精密成型关键技术研究

针对小型高精度反射面板加工易变形、装夹定位难的问题,利用CAD/CAM功能,设计与反射面板有相同曲径的专用夹具,并提出加工工艺方案。该方案有效解决了面板加工成型问题,加工精度符合生产技术要求,协助企业完成了既定的生产目标,保障了反射面板的品质,为同类零件加工中提供参考。     

Enhanced virtual machining for sculptured surfaces by integrating machine tool error models into NC machining simulation

Sculptured surface machining is a time-consuming and costly process. It requires simultaneously controlled motion of the machine axes. However, positioning inaccuracies or errors exist in machine tools. The combination of error motions of the machine axes will result in a complicated pattern of part geometry errors. In order to quantitatively predict these part geometry errors, a new application framework ‘enhanced virtual machining’ is developed. It integrates machine tool error models into NC machining simulation. The ideal cutter path in the NC program for surface machining is discretized into sub-paths. For each interpolated cutter location, the machine geometric errors are predicted from the machine tool error model. Both the solid modeling approach and the surface modeling approach are used to translate machine geometric errors into part geometry errors for sculptured surface machining. The solid modeling approach obtains the final part geometry by subtracting the tool swept volume from the stock geometric model. The surface modeling approach approximates the actual cutter contact points by calculating the cutting tool motion and geometry. The simulation results show that the machine tool error model can be effectively integrated into sculptured surface machining to predict part geometry errors before the real cutting begins.     

Increase of process reliability in the micro-machining processes EDM-milling and laser ablation using on-machine sensors

In micro production micro electric discharge machining (μEDM) and laser ablation are two established manufacturing methods. Due to the thermal material removal mechanism there are some challenges to provide the needed process reliability. In both cases it is important to ensure a precise manufacturing process by the correct positioning of the tool, e.g. the laser spot, relative to the work piece and the measurement and elimination of geometrical deviations.Using the EDM-milling process to manufacture small cavities a deviation of the manufactured depth and a waviness of the surface may appear if the compensation of the tool wear does not work correctly. A confocal white-light sensor can be used to measure the surface of the machined cavity after the EDM process. An on-machine system provides the possibility to rework the work piece without unclamping it. Combining these two procedures in an automatic working quality loop the accuracy of the manufactured depth can be improved down to a maximum deviation of less than 2 μm. Regarding the laser ablation process using ultra short pulsed Nd:YAG lasers problems arise if the focal plane is not on the surface of the work piece. Due to the manufacturing in layers occurring deviations in the surface remain until the end of the machining process. In this work an acoustical sensor is used to provide a correctly adjusted focal plane at the beginning of the first manufacturing step. Acoustic emissions are detected during the ablation process. A signal analysis of the airborne sound spectrum emitted by the process enables specific conclusions about the focal position of the laser beam. Based on this correlation an acoustic focus positioning is built up and tested on a ceramic work piece. The focal plane can then be adjusted automatically before the ablation.     

Investigation on AFM-based micro/nano-CNC machining system

To solve the problems in the atomic force microscope (AFM)-based nanomachining process such as nonlinearity and low repeatability positioning accuracy of AFM scanner in a larger scale, a novel micro/nanomachining system similar to conventional CNC machine tools was presented. The system integrated AFM with a precision stage. AFM optical lever detection method was employed to apply a very light normal load on the sample surface. An AFM diamond tip was utilized as a cutting tool to scratch the sample. The precision stage was used as a worktable to move the sample. This process was different from machining with a planer. Based on the system, effects of tip geometry, the scratching direction, the normal load, the machining velocity and the feed on the machining depth were discussed. Fabricating techniques of two-dimensional and three-dimensional complex micro/nano-structures using AFM-based mechanical scratching method based on this system were presented. Complex regular structures were fabricated. Moreover, AFM-tip-induced local anodic oxidation was also carried out based on this system, which displayed higher repeatability positioning accuracy with a larger machining dimensions and a significant machining ability of this system.     

精密特种加工是先进制造技术的重要发展方向

分析了先进制造技术的特点和发展，给出了特种加工概念的扩展和精密特种加工的范畴，介绍了非机械超精密加工技术，最后指出了特种加工技术的发展方向。     

The harmonic fitting method for the assessment of the substitute geometry estimate error. Part II: statistical approach, machining process analysis and inspection plan optimisation

The Harmonic Fitting Method (HFM), presented in the first part of this work, is here used to describe the estimate error in statistical terms. In fact, the estimate error can be considered as a random variable that depends on three different random processes: the machining, the part positioning, and the measurement processes. With the HFM it is possible to determine the moments of the estimate error (systematic value and covariance matrix) as a function of the inspection plan. It will be demonstrated that the systematic part of the estimate error derives from the systematic part of the machined surface deviations, and that the random part derives from the variability of the machining and measurement processes. In particular, the causes of the machining process variability will be analysed in terms of harmonics, thus establishing a direct relationship between the machining process and the substitute geometry estimate error. Moreover, the possibility of obtaining the probability density function of the estimate error from the HFM will be analysed, together with the problem of the inspection plan optimisation. The HFM will be used to design the optimal inspection plan for a circular geometric feature, and it will be demonstrated that, when the part positioning is subjected to a rotation uncertainty, the estimate errors of the diameter and of the eccentricity are likely to follow a Gaussian and a Rayleigh distribution, respectively. A real case of turned shafts will be considered, and the HFM optimisation of the inspection plan will be discussed.     

Chemical machining of Zerodur material with atmospheric pressure plasma jet

The material of Zerodur is widely used in high performance optics because of its excellent thermal stability characteristics. This paper deals with the development of an APPJ (Atmospheric Pressure Plasma Jet) chemical machining process for defect free and high efficiency machining of Zerodur. The APPJ chemical machining mechanism for multi-phase multi-composite materials is presented. The chemical property of the plasma jet is investigated via the atom emission spectrum analysis method and the experimental results of Zerodur material removal function and surface roughness variation with different processing parameters are discussed. Scientific explanations for the experimental observations are given.