非球面镜超精密加工系统控制软件的研究

针对非球面镜超精密加工的需要,设计了基于工控PC机和Windows2000操作系统、选用VB作为开发工具及远程传输技术,实现非球面镜超精密加工、加工误差补偿及远程数据传输等多项功能的软件控制系统.系统采用模块化设计技术,可实现初加工,补偿加工和精密测量之间数据的自动转化,满足了超精密非球面镜加工精度的要求.     

超精密加工误差补偿技术研究综述

超精密加工技术是高端制造领域的一项关键技术,当前超精密加工已进入纳米尺度,掌握超精密加工误差控制关键技术、保障并提高数控机床的加工精度,已经成为提高加工制造水平的研究热点。系统总结了超精密加工误差补偿技术研究现状及发展趋势,重点介绍了对超精密加工影响最大的几何误差、力诱导误差、热诱导误差及其补偿方法。在此基础上,深入探讨了超精密加工在几何误差分离,切削力、热诱导误差测量与补偿等方面存在的一系列问题,进一步指出超精密加工误差补偿技术还应关注其向高效、高精,通用化,模块化,智能化及柔性化的发展方向。     

基于Levenberg-Marquardt算法的超精密非球面镜面误差分析及研究

根据超精密非球面补正加工的要求,应用误差理论及其数据处理方法对其测量数据进行了分析研究,建立了优化数学模型,采用Levenberg-Marquardt(LM)优化迭代方法对数学模型进行参数拟合求解.在VC 环境下实现该算法的程序,得出形状误差PV(Peak-Valley)值.通过分析误差曲线图,来验证优化的光学参数的正确性.实例计算表明该算法能很好的应用于超精密非球面镜面形状误差分析,为评价超精密非球面镜的加工质量和后续的补正加工提供了理论依据.     

超精密车床进给伺服系统的复合控制设计

超精密车床在非球曲面以及超光滑表面的加工中具有广泛应用.将超精密车床进给系统设计成为具有电流环、速度环和位置环的三环伺服系统结构,并根据实际伺服特性,在位置环上设计了具有速度/加速度前馈补偿的半闭环复合控制策略.通过实验数据的比较,显著提高了进给伺服系统的控制精度,减少了跟踪误差.     

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。     

Research on the error analysis and compensation for the precision grinding of large aspheric mirror surface

The purpose of this paper is to propose a compensation grinding method for large aspheric mirror surface. Because the tradition grinding is not suitable for large aspheric mirror surface, in this paper, a grate parallel grinding in 3-axis and an on-machine measurement system are applied. Based on that, it presents the errors that mainly affect the form accuracy and technology of compensation grinding. An experiment of compensation grinding was carried out for large aspheric mirror surface. With the separation of decentering, wheel arc, and residual grinding system error, the PV value further decreased comparing to tradition compensation. These results indicated that this compensation can improve the form accuracy significantly in large aspheric mirror surface grinding.     

一种适合于超精密加工的特殊精密曲线插补算法

针对超精密车床提出一种新型的插补计算方法,将特殊精密曲线的插补功能集成到数控系统内部,并提出双圆弧逼近的误差的通用估计准则和生成程序段数目的估计算法。     

红外线聚光非球面透镜的单点金刚石镜面切削方法

根据硬脆性材料的延性域加工机理和面形误差补偿加工方法,研究了圆弧形和平头形刀具的单点金刚石延性域切削方法,在加工中直接获得了镜面切除面;并利用数控技术进行误差补偿,克服了因加工试验、刀具磨损、机械振动、热变形等造成的加工误差导致的非球面的面形精度降低和表面粗糙度恶化.并将该方法用于采用圆弧形刀具对红外线聚光的φ70mm非球面锗透镜进行单点金刚石切削实验中.试验结果表明面形误差补偿加工方法可以进一步消除加工误差,将非球面的面形精度PV值从微米级(1.23μm)提高到亚微米级(0.36μm)的程度,表面粗糙度R_a从亚微米级(0.27μm)改善到超亚微米级(0.04μm)的范围.     

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.     

蒙皮镜像加工误差实时补偿优化方法研究

针对传统的飞机蒙皮镜像加工误差补偿方法收敛速度慢,在大进给高速加工中很难完成较好的补偿效果的问题,提出了一种蒙皮镜像加工误差实时补偿优化方法。该方法基于双点弦截法,借助超声波测厚仪前两次获得的蒙皮壁厚与程序切削深度,计算下一点的补偿值,并通过控制镜像铣补偿轴运动实现加工误差补偿,有效的提升了飞机蒙皮镜像铣的补偿效果,减小了加工误差。最后通过有限元仿真和试验证明了该方法的优越性,最大加工误差降低了41.67%,总体加工误差降低了41.96%。     

切线法数控成形非球面机床的误差补偿

针对切线法数控成形非球面机床的速度插补原理,提出一种基于隐马尔科夫理论,结合阈值约束技术和统计学期望求值思想的误差前瞻补偿方法。在该方法的基础上建立了“切线法数控成形非球面机床”的误差补偿模型。实际应用和实验验证表明,该误差前瞻补偿方法可以有效解决数控机床的误差补偿问题,为数控系统及其他类似系统的速度插补提供了一种新的尝试。     

Critical success factors for Kaizen implementation in manufacturing industries in Mexico

To machine a noncoaxial nonaxisymmetric aspheric lens, a new parallel grinding method that employs a fixture with an adjustable gradient (AGF) is proposed. The AGF is developed for a three-axis computer numerically controlled grinding machine. The grinding method is presented according to the proposed grinding system. To ensure the machining accuracy, the main machining errors and the compensation algorithm are discussed for the grinding method using the AGF. Simulation results show that the AGF rotation errors are crucial factors affecting the profile error of the machined workpiece. Experimental results show that employing the compensation algorithm increases machining accuracy.     

Prioritization analysis and compensation of geometric errors for ultra-precision lathe based on the random forest methodology

Geometric errors remarkably affect the dimensional accuracy of parts manufactured by ultra-precision machining. It is vital to consider the workpiece shape for the identification of crucial error types. This research investigates the prioritization analysis of geometric errors for arbitrary curved surfaces by using random forest. By utilizing multi-body system (MBS) theory, a volumetric error model is initially established to calculate tool position errors. An error dataset, which contains information of 21 geometric errors, workpiece shape, and dimensional errors, is then constructed by discretizing the workpiece surface along the tool path. The problem of identifying crucial geometric errors is translated into another problem of feature selection by applying random forest on the error dataset. Moreover, the influence extent of each geometric error on the dimensional accuracy of four typical curved surfaces is analyzed through numerical simulation, and crucial geometric errors are identified based on the proposed method. Then, an iterative method of error compensation is proposed to verify the reasonability of the determined crucial geometric errors by specifically compensating them. Finally, under compensated and uncompensated conditions, two sinusoidal grid surfaces are machined on an ultra-precision lathe to validate the prioritization analysis method. Findings show that the machining accuracy of the sinusoidal grid surface with crucial geometric error compensation is better than that without compensation.     

高精度离轴凸非球面反射镜的加工及检测

为了提高离轴凸非球面反射镜的面形精度和光轴精度,研究了离轴凸非球面反射镜的加工与检测技术。首先,描述了离轴三反消像散(TMA)光学系统以及作为该光学系统次镜的离轴凸非球面反射镜的光学参数和技术指标。然后,介绍了非球面计算机控制光学表面成型(CCOS)技术及FSGJ非球面数控加工设备。最后,给出了非球面研磨阶段检测用的轮廓测量法和离轴凸非球面抛光阶段检测用的背部透射零位补偿检测法,并对背部透射零位补偿检测中离轴凸非球面反射镜光轴精度的控制技术进行了研究。检测结果表明:采用背部透射零位补偿检测法检测得到的离轴凸非球面反射镜的面形精度为0.017λ(均方根值,λ=0.632 8μm);用Leica经纬仪测量反射镜的光轴精度其结果达到9.4″,满足光学设计技术指标要求。     

A Novel Method of Efficient Machining Error Compensation Based on NURBS Surface Control Points Reconstruction

A novel method to improve the efficiency of error compensation in free-form surface machining based on the Non-Uniform Rational B-Splines (NURBS) surface control points reconstruction is proposed in this article. With the presented method, a relatively small number of inspection points are needed to be measured for error compensation. The machined surface is obtained by reconstructing the control points of the designed surface based on the on-machine measurement data. The machining error of the surface is obtained by calculating the difference between the machined surface and the designed one. Then a compensate surface is achieved using the mirror symmetry model and surface modification method to compensate the machining error. Experimental validation for the milling of a NURBS surface shows that the machining accuracy of the surface is improved by 62.57% through use of the proposed method.     

圆弧金刚石砂轮的修形及修锐技术研究

针对圆弧金刚石砂轮加工非轴对称非球面的平行磨削法中砂轮的修形精度要求较高，通常使用的水平圆弧杯状砂轮修整器很难保证加工精度的问题，提出带倾角圆弧修整器的设计方法。通过对修整器接触弧长的计算，修形延后率设计和修形补偿方法的研究及实验表明：新型圆弧修整器可满足高精度非轴对称非球面加工的要求。     

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.     

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。     

非球面超精密加工自动编程技术研究

讨论了非球面超精密加工自动编程技术中的数控插补、刀具半径补偿、工艺参数选择及编程误差分析等问题.结合研究的成果,完成了对旋转椭球面和旋转抛物面等非球面工件的加工工艺实验.     

轴对称非球面加工误差分离及补偿技术

分析轴对称非球面磨削加工中砂轮尺寸精度和形状精度等因素对加工工件精度的影响,提出适用于非球面加工的工件表面误差多参数分步分离的数学模型。新方法解决了原有加工存在的系统误差分离不彻底、补偿加工所需要的各项参数难确定等问题。试验结果表明：该数学模型更接近于理论计算轨迹,可以有效地减小加工误差,进一步提高工件的加工精度。