科技成果

大型工件外径测量系统该测量系统采用激光瞄准和激光测距技术，装有角隅棱镜的磁性定位和轻型导轨，实现了高精度大直径直接测量，同时使仪器轻便操作，能够在加工现场或加工机床上进行在位测量。关键技术包括：使用了体积小、重量轻的半导体激光长距离高精度准直系统，准直激光束光斑圆整，有效抑制了激光的漂移；轻型导轨不直线度误差实时测量与补偿，探测器位于一定距离，可同时探测五角棱镜平移和转动两项误差，实现了导轨误差的自动补偿；激光自准直瞄准被测工件直径；装备角隅棱镜和平面反射镜的磁性定位块，具有在不连续圆周表面上定…     

大型回转类工件形位误差的激光在线测量研究

回转类工件的形位误差测量是检验该类工件加工质量的重要指标,针对大型回转类工件的加工环境,给出了大型回转类工件的在线测量方案,以被测大型工件的已加工面作为定位基准面和夹紧面,使测量装置安装在被测工件上,应用激光脉冲测距技术和伺服控制技术实现对大型回转类工件形位误差的测量。     

远场光束扩展对光斑瞄准偏差影响的实验

在远场大气环境下的激光瞄准过程中,大气湍流效应会造成光束的漂移和扩展,从而影响激光器的瞄准精度。本文基于修正的VonKarman湍流谱和部分相干光在湍流大气中的传输理论,设计了高斯光波经过大气湍流后的光场模拟软件,并在一定气象条件下,通过一种激光光轴瞄准偏差测试系统进行外场实验。该测试系统光束直径≤9mm,接收部分为120mm大口径光学镜头。研究了3km范围内强湍流条件下光束的传输特性;结合实验数据,分析了在湍流大气中远场光传播时波束扩展对激光瞄准精度的影响。基于文中研究结果设计的瞄准偏差补偿方案可提高系统在大气能见度10km范围内的瞄准精度。在激光传输距离3km,斜程仰角为0~45°时,激光光斑偏移计算误差≤0.1mrad。     

数控机床主轴径向运动误差在线高精度检测

数控机床加工工件时，在切削力的作用下，用“以被加工工件为测量基准”的测量方案，实时测量机床主轴的径向运动误差．为了提高信噪比，采用基于精确重构的小波变换算法去除加工时存在的噪声．这种新算法成功地应用于自行开发的在线检测装置中。为了掌握测量系统频域特征，还从谐波抑制和总体频域特性两方面做了分析。通过实验验证了该方法的正确性。     

用于加工中心的在线工件自动测量系统

介绍一种可用于加工中心的在线工件自动测量系统的构成及功能。该系统采用新型触发式传感器 ,可使刀具刀尖自身作为测头测试工件加工尺寸。该系统可用于工件的装夹找正 ,也可对工件进行自动在线测量 ,并能根据测量结果对加工误差进行补偿以提高加工精度     

大型工件外径测量系统

该测量系统采用激光瞄准和激光测距技术,装有角隅棱镜的磁性定位和轻型导轨,实现了高精度大直径直接测量,同时使仪器轻便操作,能够在加工现场或加工机床上进行在位测量。关键技术包括：使用了体积小重量轻的半导体激光长距离高精度准直系统,准直激光束光斑圆整,有效抑制了激光的漂移;轻型导轨不直线度误差实时测量与补偿,探测器位于一定距离,可同时探测五角棱镜平移和转动两项误差,实现了导轨误差的自动补偿;激光自准直瞄准被测工件直径;装备角隅棱镜和平面反射镜的磁性定位块,具有在不连续圆周表面上定位和测量的双重功能;计…     

基于双频激光干涉技术的轴径测量原理的研究

大型工件内外径测量点的瞄准和定位是大直径测量中的一个关键技术,也是国内外未能很好解决的测量问题.采用激光准直仪出射的高稳定光线瞄准和定位吸附在被测工件直径两端点上的两个磁性定位块上的光电接收器,同时使用双频激光干涉仪直接测量出这两个光电接收器中心间的距离,通过几何计算得到被测直径大小.实验表明,该方法测量精度较高,测量系统的相对误差小于5×10-6.     

用于大尺寸工件的动态长度测量系统

针对移动大尺寸工件的表面形貌特点,利用二维激光三角法构造出水平和垂直虚拟测量基准面;结合多传感器融合准则,建立了一种新型的大尺寸工件测量模型,并利用该模型实现了移动工件两端端面到虚拟测量基准面的位移非接触测量。采用误差分离方法自修正理论误差和运动误差的影响;结合人机交互界面,研制了高精度、低成本的移动大尺寸工件长度自动检测系统。利用该系统对在(1 000±25)mm内以不同速度运动的圆柱体大尺寸工件长度进行检测,得到的检测分辨力为10μm、检测精度为100μm、工件移动速度为5cm/s。实际运行结果表明,该系统安全、稳定、快速,可满足工业在线生产中对同类型规则的大尺寸工件控制和检测的要求。     

大型薄板曲面件在机测量技术的研究

为解决大型钣金曲面件因体积大、易变形、装卸不便等给测量带来的困难,提出了一种曲面测量的新方法即在机原位测量方法,并将其成功应用于某大型曲面件喷丸成形机上,实现了大型喷丸成形曲面件的在机测量.该测量方法使测量与加工采用同一基准,消除了因基准不重合带来的测量误差,提高了测量精度:避免了工件的重复装夹,提高了测量效率.采用曲线曲面匹配和误差分离技术对测量数据进行处理,完成了对被测件的评价.大型喷丸成形曲面件在机原位测量系统的研制成功验证了所提出的测量方法是可行的.     

大型旋转工件直径在线检测系统及误差分析

激光三角法是一种光电检测技术,可以实现长度、距离以及三维形貌检测,测量系统结构简单、测量速度快、能够进行数据的实时处理。基于激光三角测距技术,提出了一种大型旋转工件直径在线测量方法及系统,给出了测量系统的组成结构,对测量系统中主要误差源进行了分类,重点针对系统误差,进行了影响测量精度的误差定量和定性分析,并进行了仿真分析,为以后研究一种大型旋转工件直径自主在线测量机器人奠定了理论基础。     

Repetitive Measurement and Compensation to Improve Workpiece Machining Accuracy

Achieving workpiece high accuracy at low cost is one of the greatest challenges in the manufacturing industry. A repetitive error measurement and compensation scheme to improve the workpiece diameter accuracy for machining centres is des-cribed. The scheme entails an on-machine measurement and error compensation technology between machining processes. The workpiece diameters are measured along the workpiece length by using a fine touch sensor. The workpiece diameters in the compensation program are modified for implementation of next pass error correction. The technology is realised on a CNC turning centre. This method works well in hard machining and turned workpieces with large length–diameter ratios where the machining process induced errors are significantly greater than errors from other sources. It demonstrates that the work-piece can obtain maximum possible machining accuracy by this repetitive measurement and compensation technique.     

Application of projection pursuit regression to thermal error modeling of a CNC machine tool

Thermal errors are the major contributor to the dimensional errors of a workpiece in precision machining. Error compensation technique is a cost-effective way to reduce thermal errors. Accurate modeling of errors is a prerequisite of error compensation. In this paper, a thermal error model was proposed by using projection pursuit regression (PPR). The PPR method improves the prediction accuracy of thermal errors in the computer numerical control (CNC) turning center. A thermal error compensation system was developed based on the PPR model, and which has been applied to the CNC turning center in daily production. The results show that the thermal drift in workpiece diameter has been reduced from 34 to 5???m.     

Application of ACO-BPN to thermal error modeling of NC machine tool

Thermal errors are the major contributor to the dimensional errors of a workpiece in precision machining. Error compensation technique is a cost-effective way to reduce thermal errors. Accurate modeling of errors is a prerequisite of error compensation. In this paper, four key temperature points of a NC machine tool were obtained based on clustering method. A thermal error model based on the four key temperature points was proposed by using ant colony algorithm-based back propagation neural network (ACO-BPN). The ACO-BPN method improves the prediction accuracy of thermal deformation in the NC machine tool. A thermal error compensation system was developed based on the proposed model, and which has been applied to the NC machine tool in daily production. The results show that the thermal drift in workpiece diameter has been reduced from 33 to 8 μm from its center of tolerance.     

数控随动磨床加工凸轮方法及其精度补偿策略

针对凸轮随动磨削中因工件轴转速差、伺服系统响应偏差、硬件制造误差等重复性误差影响因素造成的零件制造精度下降问题,将在线测量技术和Sinumerik 840D数控系统的插补表与电子齿轮功能应用到机床运动控制系统中,开展了随动磨削工艺的运动轨迹和控制方案分析,提出了由内嵌在系统PCU上的VB程序来处理在线测量获得的360个离散误差补偿数值,自动生成带插补表与电子齿轮功能的专用加工程序,利用同轴运动叠加控制方法,把补偿值叠加到进给轴上,使带误差补偿数据的凸轮加工NC程序不断根据实际加工状态更新,最后在工程样机上进行了磨削试验。试验结果表明,发动机凸轮轴的廓型最大加工误差降到了2.6μm以下,残余误差主要来源为机械振动、非线性摩擦扰动等随机性偏差。该运动控制和误差补偿方法能在实际加工中较好地补偿重复性误差因素对工件精度产生的影响。     

基于FANUC 31i的主轴热变形补偿方法

主轴高速旋转时,主轴轴承内外环高速摩擦产生大量热量,这些热量使主轴轴向和空间姿态发生变化,产生热伸长、热倾斜和热漂移等形变,这些形变又引起刀具与工件相对位置发生变化,导致工件加工精度变差。采用五点测量法对这些形变量进行测量,生成主轴温升与热变形的误差曲线,再根据误差曲线编制数控系统可执行的C语言热补偿程序或PMC热补偿程序,数控系统根据温差变化自动更新外部机械原点偏移量,纠正刀具与工件的相对位置偏差,可有效减小主轴热变形引起的误差,提高工件加工精度。     

Comprehensive thermal growth compensation method of spindle and servo axis error on a vertical drilling center

This paper deals with the modeling of comprehensive thermal growth of spindle and servo axis. Thermal errors of a vertical drilling center TC500 were measured using a spindle error analyzer and a laser interferometer, thermal error of servo axis was decomposed, and each term analyzed. Spindle thermal growth model based on temperature variation including an identification method for the parameters of the suggested model was presented. Similarly, the servo axis models for thermal expansion error (TEE) in the stroke range and the thermal drift error (TDE) of origin were derived based on heat-transfer mechanism, and the parameter identification method was presented. The experimental results indicate that by applying the proposed model, high accuracy stability can be achieved, even when the moving state changes randomly. A specific machining process of the upper surface of a rectangular workpiece was designed to verify the effects of error compensation to the unaided eye. The machining results indicate that the proposed model has high accuracy and strong robustness in compensating the comprehensive thermal error.     

基于多波长协作的切削液残留表面激光位移测量误差补偿方法

在加工测量一体化过程中,工件表面切削液残留形成的油膜会严重影响光学在机测量的精度。 现有的误差补偿方法通 常需要获取油膜介质的先验信息,如成分、厚度等。 而这些信息受加工形质、切削液随机分布等因素的影响难以实时获取。 为 此,本文提出一种基于多波长协作的切削液残留表面激光位移测量误差补偿方法。 首先设计并搭建了基于激光三角位移测量 的多波长激光测量系统,可利用多波长激光测量同一被测点位移。 通过引入柯西色散规律,建立光学系统与激光波长的解析关 系,并基于此推导出多波长激光测量内在的差分特性,最终实现误差补偿。 本文依此方法进行了实验。 结果表明补偿后测量误 差绝对值小于 0. 01 mm,与未补偿的测量数据对比,误差降低了至少 92% 。     

MODELING AND COMPENSATION TECHNIQUE FOR THE GEOMETRIC ERRORS OF FIVE－AXIS CNC MACHINE TOOLS

One of the important trends in precision machining is the development of real-time error compensation technique. The error compensation for multi-axis CNC machine tools is very difficult and attractive. The modeling for the geometric error of five-axis CNC machine tools based on multi-body systems is proposed. And the key technique of the compensation-identifying geometric error parameters-is developed. The simulation of cutting workpiece to verify the modeling based on the multi-body systems is also considered.     

Intelligent dimensional error pre-compensation in CNC grinding using iterative learning approach

This paper focuses on the problem of intelligent compensation of nonlinearly appeared dimensional error in the computer numerical control grinding process. An intelligent error pre-compensation scheme is proposed with intelligent controller, automatic dimensional error measurement, and feedback information. Iterative learning approach is applied to infer the error compensation of the next workpiece machining by using the historical data. The simulation results and the real system input and output responses show that the proposed intelligent error compensation scheme and the iterative learning approach have significant superiority.     

An automatic leveling method for the stage of precision machining center

The stage of precision machining center will deform under the weight of large workpiece which is put on it. The deformation will cause the workpiece to incline, and moreover, affect the machining accuracy, which cannot be neglected especially in large-scale combined precision machining centers. To resolve this problem, after simulating the deformation of the stage, this paper introduced an automatic leveling method for the precision stage and gave a method to calculate the regulating variables of each supporting point of the stage. In order to verify these methods, an experiment was done on an experimental stage which was designed and built on the basis of the stage of precision machining center. Experimental results showed that the tilt error of the stage can be reduced with these methods and the machining error of the workpiece declined by 90% after leveling. The experiments also verified the accuracy and feasibility of the automatic leveling method.