加工中心的几何误差和热误差综合补偿模型

本将剂次坐标变换理论结合刀具与工件联结链矢量概念建立了加工中心误差运动综合偿模型。此模型不但包了三轴加工中心的几何误差而且还饮食了热误差的共计35个误差元素,使用此模型的补偿加工大幅度地提高了加工中心的加工精度。该方法可对多轴设备和机器人的非网体误差运动进行描述。     

精密车削中心热误差和切削力误差综合建模

热误差和切削力误差是影响数控机床精度的最重要的两个误差源,误差补偿技术是一种消除机床误差经济有效的方法,而有效的误差补偿依赖于准确的误差模型。在对切削加工过程中的热变形和切削力分析的基础上,选取合理的参量,采用BP神经网络和PSO算法相结合的优化方法建立了热误差和切削力综合模型。BP-PSO建模方法改善了网络模型的收敛速度和预测精度。基于所建误差模型,对一台精密车削中心加工实时补偿后使得径向加工误差从27μm提高到8μm,大大提高了车削加工中心的加工精度,验证了模型精度。     

数控机床热误差的建模与预补偿

研究了数控机床热误差的预补偿方法。建立了基于主轴转速的热误差自回归模型,从而不需要测量机床的温度场就可以预测热误差。在加工前通过修改工作的数控加工程度即可进行补偿,大大简化了误差补偿过程。可应用于中等精度的数控机床。     

基于周期分解的机床主轴回转误差预报模型

随着精密机械、惯性技术和宇宙科学等学科的发展 ,超高精密零件在这些领域有着重要用途。但是其制造以及测量均受到主轴回转误差的限制。当今加工预测补偿控制已成为精密加工技术的一个发展研究方向。依靠传统的主轴回转误差预测模型仅仅能补偿掉误差成分中可表达的重复误差。本文对主轴回转误差采用了基于周期分解的组合建模方法 ,建立了更有效的预测模型。仿真实验结果表明该模型提高了回转误差的预报精度 ,为预测补偿精密加工技术奠定了基础     

超薄件加工变形误差补偿的研究（英文）

超薄件可广泛应用于高精度微型器件、光子系统等领域.针对加工后超薄件的较大变形,采用基于超精密车削的误差补偿方法进行研究.提出补偿理论与补偿方法,对原位面形误差与离线面形误差进行测量,利用补偿理论计算得到补偿面形,最后采用三轴伺服控制技术对超薄件变形误差进行车削补偿.补偿加工的超薄铝几何尺寸为Φ20×0.1 mm,一次补偿加工后,工件面形峰谷值由变形产生的误差从15μm降到10μm,具有较好的补偿效果.对补偿中原位测量误差与位置偏移误差进行讨论,提出提高补偿加工精度的方法.     

收发分体式四自由度激光测量系统耦合误差建模与补偿

线性导轨广泛应用于精密机床和仪器,其运动精度直接影响所在设备的空间定位精度。针对团队前期研制的收发分体式四自由度激光测量系统可以测量导轨直线度、俯仰角和偏摆角,但其直线度与角度测量结果间存在耦合干扰问题,提出了一种误差建模与补偿方法。根据激光测量系统的原理和结构,分析并确定了耦合误差的主要来源,利用矩阵光学及齐次坐标变换的方法建立了耦合误差的补偿模型。以雷尼绍XL-80型激光干涉仪为基准,对所建立的误差补偿模型进行了实验验证,结果表明:利用所建模型补偿后的直线度和角度测量误差均降低了75%以上。所提出的误差建模与补偿方法不但有助于提高四自由度激光测量系统的精度,同时也有助于降低其成本。     

基于斜置锥台的五轴数控机床加工精度预测技术

为缩短基于斜置锥台评价五轴联动加工精度的时间和降低评价的费用,用多轴机床误差理论研究了基于锥台的五轴机床联动加工精度预测,提出了一种新的五轴机床加工精度评价方法.该方法利用齐次坐标变换理论建立斜置锥台的五轴加工运动误差模型,在计算机辅助制造(CAM)软件上进行斜置锥台的仿真加工得到斜置锥台刀侧铣削的数控(NC)代码,并...     

超精密磨削大型光学非球面元件的研究

介绍了加工大型光学非球面的超精密数控磨削系统，给出了用来生成NC加工软件的加工非球面时砂轮的中心位置的求解模型，在此基础上讨论并给出了由砂轮安装产生的砂轮与工件主轴的偏心误差形成的加工工件面形误差的计算模型，并提出有效的工具路径补偿方法。通过计算机模拟验证了这种补偿方法的可靠性。     

弯扭小带冠导叶片的加工工艺分析

本文根据弯扭小带冠导叶片的特点,在其制造的过程中利用MasterCAM、Pro/E联合造型.采用数控卧式加工中心加工基准,数控立式四轴加工中心加工汽道部分型线,有效的提高了叶片汽道精度,从而得出一条合理的方案。     

基于BP神经网络模型的MEMS加速度计误差补偿方法

现阶段普遍采用多元线性回归对加速度计误差建模,并利用最小二乘法对模型参数辨识,但其对加速度计精度提高有限,因此该文提出一种基于BP神经网络模型的MEMS加速度计误差补偿方法。该方法利用BP神经网络建立加速度计误差模型,通过多位置翻滚进行实验数据测量,并对模型进行训练,最后利用训练好的模型对加速度计误差进行补偿。比较多元线性回归和BP神经网络建模对加速计误差补偿结果,其标准偏差分别为0.001 9 g和0.000 16 g。结果表明误差下降一个数量级,说明BP神经网络能有效地补偿加速度计误差。     

Kinematic error modeling and error compensation of desktop 3D printer

Desktop 3D printers have revolutionized how designers and makers prototype and manufacture certain products.Highly popular fuse deposition modeling(FDM)desktop printers have enabled a shift to low-cost consumer goods markets,through reduced capital equipment investment and consumable material costs.However,with this drive to reduce costs,the computer numerical control(CNC)systems implemented in FDM printers are often compromised by poor accuracy and contouring errors.This condition is most critical as users begin to use 3D-printed components in load-bearing applications or to perform mechanical functions.Improved methods of low-cost 3D printer calibration are needed before their open-design potential can be realized in applications,including 3D-printed orthotics and prosthetics.This paper applies methodologies associated with high-precision CNC machining systems,namely,kinematic error modeling and compensation coupled with standardized test methods from ISO230-4,such as the ballbar for kinematic and dynamic error measurements,to examine the influence and feasibility for use on low-cost CNC/3D printing platforms.Recently,the U.S.Food and Drug Administration's"Technical considerations for additive manufactured medical devices"highlighted the need to develop standards specific to additive manufacturing in regulated manufacturing environments.This paper shows the benefits of the methods described within ISO230-4 for error assessment,alongside applying kinematic error modeling and compensation to the popular kinematic configuration of an Ultimaker 3D printer.A Renishaw ballbar QC10 is used to quantify the Ultimaker's errors and thereby populate the error model.This method quantifies machine errors and populates these in a mathematical model of the CNC system.Then,a post-processor can be used to compensate the printing code.Subsequently,the ballbar is used to demonstrate the dramatic impact of the error compensation model on the accuracy and contouring of the Ultimaker printer with 58%reduction in overall circularity error and 90%reduction in squareness error.     

Modeling and identification of the multi-axis drive system using support vector machine and granular computing

Advanced manufacturing technology requires high-precision capability in multi-axis computer numerical control (CNC) machine tools. At present, the modeling and identification for the drive system of CNC machine tools has some defects. In order to solve the problem, some interdisciplinary theories and methods, such as support vector machines, granular computing, artificial immune algorithms, and particle swarm optimization algorithms, have been used to model and identify multi-axis drive systems for CNC machine tools. An identification method using a support vector machine, based on granular computing, is presented to identify a multi-axis servo drive system model for improving the precision of model identification, and an immune particle swarm optimization algorithm, based on crossover and mutation functions, is proposed to optimize the structure parameters of the support vector machine based on granular computing. The proposed identification method was evaluated by experiments using the multi-axis servo drive system. The experimental results showed that the proposed approach is capable of improving modeling and identification precision.     

Enhancement of accuracy of multi-axis machine tools through error measurement and compensation of errors using laser interferometry technique

The present era is witnessing advancement in digital electronics and microprocessor which enables manufacturing sector capable to produce complex components within small tolerance zone in the tune of nanometre and at one machining center. All motion control systems have some form of position feed back system fitted with the machine. Such systems are not generally accurate due to the errors in the positioning performance of the machine tool which will change over time to time due to wear, damage and environmental effects. The complex structure of multi-axis CNC machine tools produce an inaccuracy at the tool tip caused by kinematic parameter deviations resulting in manufacturing errors, assembly errors or quasi-static errors. Analysis of these errors using a laser measurement system provides the manufacturers a way to achieve better accuracy and hence higher quality output from these processes. In this communication, techniques to measure the linear positional errors of axes of CNC machine tools by a laser interferometer calibration system and accuracy enhancement using the data obtained from the calibration cycle by feeding into the machine’s controller with the help of linear error compensation package are discussed.     

主轴回转运动精度的评定误差

利用刚体平面运动的瞬心理论,把主轴的回转运动作为刚体的平面运动来研究,定义了主轴的回转轴心误差的概念。提出了用回转中心误差定义的车削类主轴回转运动精度的评定误差和用回转轴心误差定义的镗削类主轴回转运动精度的评定误差的概念。并解决了加工精度与主轴回转运动精度的定量关系。     

自回归分布滞后模型在数控机床热误差建模中的应用

对多元线性回归模型、回归与残差AR叠合模型和自回归分布滞后模型3种热误差建模方法进行了介绍与比对分析。多元线性回归模型方法简单快捷,但因热误差呈非线性且具有互交作用,较难获得精确热误差数学模型。后两个模型均属时间序列分析方法,其优点是能够比较精确地建立热误差数学模型,两者的区别是叠合模型把参数估计分成两部分,而自回归分布滞后模型是统一估计参数,因此叠合模型的精度要低于自回归分布滞后模型精度,并通过实例验证,自回归分布滞后模型在精密数控机床热误差建模中具有较好的建模精度。     

考虑结构热变形的机床进给系统热误差研究

为系统研究精密机床进给系统热误差的形成机理及其影响因素，提出了一种考虑结构热变形的进给系统热误差建模方法。在考虑进给系统内生热源及冷却系统对丝杠螺母副的温升和丝杠热变形作用机制的前提下，同时考虑了进给系统内生热源对精密机床结构大件（床身、立柱、溜板）热态特性的影响规律。通过分析结构热变形引起的进给系统电机座和轴承座相对位置的变化，建立了综合考虑结构大件和丝杠热变形的进给系统热误差模型。以JIG630精密卧式加工中心为例，进行了考虑结构热变形和不考虑结构热变形的进给系统热误差建模与仿真分析，并开展了相应的测试验证实验。结果表明考虑结构热变形的进给系统热误差模型仿真值与实验结果具有更高的一致性。该建模方法对精密机床进给系统热平衡设计、热误差的控制与补偿具有重要参考意义。     

THE DESIGN AND DEVELOPMENT OF A LARGE ULTRA-PRECISION CNC DIAMOND TURNING MACHINE

The Cranfield Unit for Precision Engineering (CUPE) specializes in the design, development, and construction of advanced, high precision CNC machines of many types. Two years ago, the British Science & Engineering Research Council (SERC) commissioned CUPE to develop and commission an ultra-precision CNC diamond turning machine for the manufacture of X-ray telescope mirrors up to 1400 mm in diameter and 600 mm in axial length. This vertical axis machine incorporates many novel design and manufacturing features. This paper describes the design and manufacturing philosophies and techniques used in bringing it to its present successful level of development.     

用激光干涉仪检测双丝杠驱动加工中心的方法与评定

介绍了使用激光干涉仪检测双丝杠驱动加工中心时,选择测量轴线的有效位置,能够真实地反映加工中心轴线的运动定位状态;提出检测双丝杠驱动加工中心定位精度和重复定位精度的方法,通过调整激光干涉仪和位移镜组件的安装位置,获得数控机床及加工中心的检测精度,并根据自动采集获得的测量数据进行有效地补偿,以提高和恢复数控机床及加工中心的最佳定位精度.     

Research on error control and compensation in magnetorheological finishing

Although magnetorheological finishing (MRF) is a deterministic finishing technology, the machining results always fall short of simulation precision in the actual process, and it cannot meet the precision requirements just through a single treatment but after several iterations. We investigate the reasons for this problem through simulations and experiments. Through controlling and compensating the chief errors in the manufacturing procedure, such as removal function calculation error, positioning error of the removal function, and dynamic performance limitation of the CNC machine, the residual error convergence ratio (ratio of figure error before and after processing) in a single process is obviously increased, and higher figure precision is achieved. Finally, an improved technical process is presented based on these researches, and the verification experiment is accomplished on the experimental device we developed. The part is a circular plane mirror of fused silica material, and the surface figure error is improved from the initial λ/5 [peak-to-valley (PV) λ=632.8 nm], λ/30 [root-mean-square (rms)] to the final λ/40 (PV), λ/330 (rms) just through one iteration in 4.4 min. Results show that a higher convergence ratio and processing precision can be obtained by adopting error control and compensation techniques in MRF.