单晶硅反射镜的超精密磨削工艺

为了实现单晶硅反射镜高效低损伤的超精密加工,研究了基于工件旋转法磨削原理的单晶硅反射镜超精密磨削工艺。通过形貌检测和成份测试的方法分析了该工艺采用的超细粒度金刚石砂轮的组织结构特征,并对单晶硅进行了超精密磨削试验,研究了超细粒度金刚石砂轮的磨削性能。通过砂轮主轴角度与工件面形之间的数学关系实现对磨削工件面形的控制。最后,采用超细粒度金刚石砂轮对Φ100mm×5mm的单晶硅反射镜进行了超精密磨削试验验证。试验结果表明,超细粒度金刚石砂轮磨削后的单晶硅表面粗糙度Ra值小于10nm,亚表面损伤深度小于100nm,磨削后的单晶硅反射镜面形PV值从初始的8.1μm减小到1.5μm。由此说明采用该工艺磨削单晶硅反射镜能够高效地获得低损伤表面和高精度面形。     

采用ELID磨削技术对铜和铝的精加工实验研究

为了研究铜和铝材料超精密加工的新途径,采用在线电解修整砂轮(ELID)精密磨削技术,对其进行镜面磨削实验,分析加工表面的形成机理及影响因素。实验结果表明:砂轮粒度、砂轮线速度和磨削力是影响表面加工质量的主要因素。当砂轮线速度由16m/s提高到20m/s时,表面粗糙度Ra由0.76μm下降到0.44μm;当砂轮的粒度过大(120#)或过小W(1.5)时,加工出的工件表面精度都很低;得到在砂轮线速度为20m/s和砂轮粒度为W10时,磨削效果最佳,但也不能很好地提高铜和铝的表面质量和降低表面粗糙度,得到的铜和铝表面粗糙度分别只能为0.44μm和0.75μm。     

复杂曲面碳化钨密封零件精密磨削实验研究

碳化钨为典型的碳化物陶瓷材料,具有广泛的应用前景。其具有高硬度、高脆性及很高的耐磨性,所以难以采用传统的车削、铣削等工艺进行加工。在碳化钨工件上加工出复杂的曲面结构,并保证工件的面形精度及表面粗糙度则更加困难。为获得高表面质量的复杂曲面碳化钨密封工件,采用杯形金刚石砂轮单点磨削的方法实现碳化钨材料加工;设计压电陶瓷驱动柔性铰链微进给机构精确控制砂轮切深方向运动,从而实现复杂曲面加工的成形运动;探索最优工艺参数获得高面形精度和低表面粗糙度。分析了碳化钨磨削加工材料去除机理,以此指导柔性铰链精密进给机构设计,并规划杯形砂轮改善面形精度及表面粗糙度的磨削方法。实验结果表明:采用青铜基及树脂基杯形砂轮以45°倾角单点磨削碳化钨样件,其表面粗糙度值Ra由初始的500nm减小到15nm,面形精度RV值达到0.25μm。该装置可以在普通机床上磨削出高质量的碳化钨工件。     

微小非球面光学模具单点斜轴误差补偿磨削

针对微小非球面光学透镜模具的纳米单点斜轴误差补偿磨削进行研究。通过分析比较传统的直交轴磨削法,提出微小非曲面光学模具的单点斜轴磨削方式,有效避免微细砂轮在加工微小非球面时发生干涉情况;采用单点恒定磨削方式提高微小非球面磨削的稳定性及精度。通过分析磨削区域内微细砂轮与微小非球面的干涉情况,从而合理计算并选用较高强度的微细砂轮。提出微小非球面误差补偿磨削策略,分析砂轮的对心误差(x轴向和y轴向)对形状精度的影响,采用法向残余误差补偿的方法对加工后的形状误差进行超精密补偿磨削。利用超精密磨床对口径为2 mm的超硬热压模具碳化钨材料的微小非球面进行纳米单点斜轴误差补偿磨削试验,经过三次超精密磨削及误差补偿循环,其形状精度PV从1 034 nm改善至146 nm,表面粗糙度达到Ra2.19 nm。     

无结合剂碳化钨非球面模具的超精密磨削加工

针对无结合剂碳化钨材料,进行非球面模具的法向磨削试验研究。分析法向磨削非球面时的砂轮对刀误差对磨削精度的影响,研究无结合剂碳化钨非球面模具的磨削表面形貌特征和最终表面质量,优化误差补偿工艺,并利用聚焦离子束对磨削后的非球面亚表层损伤进行成像分析。研究结果表明利用推导的砂轮对刀误差方程,可以在磨削加工前对砂轮的初始位置进行精确调整,提高磨削加工精度。磨削后无结合剂碳化钨非球面模具不同区域的表面质量不同,距非球面中心越近,磨削质量越好,距中心越远,磨削质量越差。经过3次误差补偿磨削加工后,最终的无结合剂碳化钨非球面模具的面形精度误差均小于0.3μm(PV值),表面粗糙度平均值小于8 nm(Ra值),亚表层没有明显的裂纹产生。     

ELID精密镜面外圆磨削技术的应用

在线电解修整（ELID）精密镜面磨削有效地实现了许多难加工材料的平面精密加工和高效加工。本文介绍了ELID磨削技术在精密镜面外圆磨削上的应用。通过采用金属基超硬磨料砂轮在线电解修整对硬质合金,碳化硅陶瓷进行精密镜面外圆磨削,得到了表面粗糙度Ra=0.025-0.0028μm的加工表面。     

ELID精密镜面外圆磨削技术的应用

在线电解修整(ELID)精密镜面磨削有效地实现了许多难加工材料的平面精密加工和高效加工.本文介绍了ELID磨削技术在精密镜面外圆磨削上的应用.通过采用金属基超硬磨料砂轮在线电解修整对硬质合金、碳化硅陶瓷进行精密镜面外圆磨削,得到了表面粗糙度Ra=0.025～0.028μm的加工表面.     

光学玻璃塑性模式超精密磨削加工的研究

利用超精密磨床磨削加工6种典型的光学玻璃,先从理论上研究了脆性材料脆塑转变的临界值,然后对脆性材料作了大量磨削实验,实验结果表明,超精密磨削脆性材料时存在着断裂模式,断裂与塑性模式、塑性模式,这些模式主要由砂轮磨粒的切削深度进行控制,该磨削表面粗糙度与磨粒尺寸的大小,砂轮的进给量及玻璃的材料有关,当光学玻璃在塑性模式磨削时,其表面层不会产生任何裂纹缺陷,利用超精密磨床进行磨削加工,获得的表面粗糙度Ra低于5nm。     

在线电解修整（electrolytic in-process dressing，EIPD）

金属基超硬磨料砂轮在线电解修整(EIPD)超精密镜面磨削技术是日本理化学研究所大森整博士等于1987年开发的超精密加工新技术，是对超精密磨削加工技术的重大改进。此技术可用于加工各种金属和非金属硬脆(如陶瓷、玻璃等)材料，适用性广泛，加工后的表面粗糙度Ra值可达到纳米级。     

应用环形磁场控制的微粉砂轮制备及其磨削性能

在超精密磨削中,金刚石微粉砂轮的磨粒分布均匀性对提高磨削表面质量至关重要,为了使微粉磨粒规则排布,提出了一种采用环形磁场控制磨粒规则排布的砂轮制备方法,制备了多种金刚石微粉砂轮,使用磁场控制制备的微粉砂轮对硬质合金YG8进行了平面及非球面磨削试验。结果表明:应用环形磁场控制可使金刚石微粉砂轮的磨粒实现规则排布,极大改善砂轮加工性能,利用环形磁控方法制备的砂轮可获得最佳表面粗糙度Ra3 nm、最佳面形精度PV318 nm的光滑镜面。     

小口径非球面斜轴磨削及磁流变抛光组合加工工艺及装备技术研究

为提高小口径非球面模具加工效率和加工精度,提出一种结合斜轴超精密磨削和斜轴磁流变抛光的组合加工方法,将两种超精密加工方法集成在一台机床上,以缩短装夹时间以及降低装夹误差。研制新型的小口径非球面超精密复合加工机床,对直径Ф6.6 mm的非球面碳化钨模具进行了加工试验。斜轴磨削后加工表面粗糙度达到R_a 6.8 nm,斜轴磁流变抛光后表面粗糙度达到R_a 0.7 nm,面型精度可以达到PV 221 nm。结果表明,所开发的小口径非球面超精密复合加工装备能达到加工要求,可有效提高加工精度和加工效率。     

Rhenium-iridium coating effect of tungsten carbide mold for aspheric glass lens

Recently, with increasing lightness and miniaturization of high resolution camera phones, the demand for aspheric glass lens has increased because plastic and spherical lenses are unable to satisfy the required performance. An aspheric glass lens is fabricated by high temperature and pressure molding using a tungsten carbide molding core; so precision grinding and coating technology for the molding core surface is required. In this paper, Aspheric glass lens for 5 megapixel 4 time zoom camera phone modules was developed. The grinding condition of the tungsten carbide molding core was found after applying design of experiments (DOE). Also, the ultra-precision grinding process was investigated under this condition by experiment. Rhenium-iridium (Re-Ir) coating was applied on the ground surface of the tungsten carbide molding core. The influence of Re-Ir coating was compared and evaluated. The surface roughness of the molding core were improved by application of Re-Ir coating on the surface of the tungsten carbide molding core. Aspheric lenses were also molded with the non-coated molding core and the Re-Ir coated molding core. The surface roughness of the aspheric glass lens improved by about 0.4 nm (aspheric surface) and 0.5 nm (plane surface).     

Modeling and simulation of grinding surface topography considering wheel vibration

Grinding is an important means of realizing precision and ultra-precision machining. Vibration caused by an unbalanced grinding wheel in grinding process has a significant impact on the quality of workpiece surface. However, the effect of wheel surface topography and/or the relative vibration between grinding wheel and workpiece are not considered in most researches. Taking the relative vibration between grinding wheel and workpiece into account, alongside the abrasive grain trajectory equation, a new analysis and simulation model for surface topography of the grinding process is established. The model for the topography of the grinding wheel surface is first studied, and subsequently, a new simulation model for surface topography of the grinding process is proposed. Case studies are performed at the end, and the influence of grinding wheel vibration amplitude, wheel grit number, as well as grinding parameters on the surface waviness and roughness is discussed. The simulation results could be used to optimize the actual grinding process to improve the ground surface quality or predict the surface topography by given grinding parameters.     

超精密非球面镜面模具直轴磨削的研究

研究了非球面镜面模具直轴超精密磨削技术,给出了非球面镜面模具超精密加工机理、算法原理、软硬件结构、系统实现、工艺分析及实例应用,开发了小型超精密非球面镜面加工系统SGTCAM1.0.研究结果表明,系统原理正确,加工出的非球面光学零部件形状误差在100 nm以下,表面粗糙度在5 nm以下,达到纳米级加工精度.开发的系统使用方便,成本低.     

磨削条件的优化及表面粗糙度的预测与控制

利用信噪比试验设计法和二次回归设计技术,对平面磨削中砂轮转速、工件速度、径向进给量及砂轮粒度等因素对表面粗糙度的影响规律进行了分析,各因素对表面粗糙度的影响由大到小依次为砂轮粒度、径向进给量、砂轮转速和工件速度。同时建立起表面粗糙度的回归预测模型,并以F检验法对其进行检验,回归预测模型的显著性水平为0.01,回归效果良好。     

超精密非球面镜面计算机辅助设计与应用

非球面镜面加工技术的研究已经成为先进制造技术的核心问题之一,相关的超精密装备制造关键技术除了机床本体,最重要的是系统控制软件及应用软件的开发,这是制约自主产权的超精密加工装备技术发展的瓶颈问题之一。结合作者在日本从事NEDO项目合作的实际经验,深入细致地阐述了超精密非球面镜面计算机辅助设计(CAD)系统的算法原理、系统结构及系统实现,并通过实际的光学镜面设计实例,介绍SGT-CAM软件系统具体开发及应用,为超精密非球面镜面的计算机辅助加工打下了基础。该系统已经成功地应用于自行开发的小型超精密镜面加工机SGT100上,形状误差小于100纳米,表面粗糙度小于5纳米,得到有关专家的充分肯定。     

Quasi-static kinematics model for motion errors of closed hydrostatic guideways in ultra-precision machining

Aspheric optics has been widely employed in some high-tech industries for its superiority. In order to achieve the ultra-precision machining of these aspheric surfaces, the large optical ultra-precision grinding machine becomes crucial because it determines the efficiency of the whole process. As the key functional unit in ultra-precision machine tool, the hydrostatic guideways are commonly adopted for the excellent performance. However, the motion errors of hydrostatic guideways have a direct influence on the accuracy of the machined workpiece, and some analysis approaches have been reported correspondingly. Although the existed analysis models do work, their imperfections also can be easily captured. Accordingly, a novel analysis model with less imperfection is deserved to be developed. In this paper, the kinematic theory is utilized to establish the quasi-static analysis model for motion errors in closed hydrostatic guideways. Through the large ultra-precision grinding machine designed by our research group, the consistently good agreement between the predicted results and the measured experimental data are obtained. Furthermore, it is found that the motion accuracy is more sensitive to the profile error of the guide rail bearing the external load rather than that of the other guide rail in the closed hydrostatic guideway. The presented research is supposed to be valuable to the peer designers.     

离轴非球面超精密磨削加工几何模型的探讨

在用来加工轴对称非球面的二轴联动超精密数控机床的工件主轴上安装可以精确给出旋转角度的码盘，采用柱坐标加工方式进行离轴非球面的超精密磨削加工。在给出离轴非球面方程的基础上，给出数控加工离轴非球面的相应的几何模型。计算机仿真验证了该加工方法的简便性与可靠性。该加工方法可以降低设备投入，提高生产效率。