共查询到20条相似文献,搜索用时 86 毫秒
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Fan LiangZhi A.Y. Elatta Li XiaoPing 《The International Journal of Advanced Manufacturing Technology》2005,25(7-8):730-734
The measurement method is a decisive step for any calibration method. This paper studies the practical performance of a 5DOF manipulator based on a 3-RPS parallel mechanism. By comparing the controlling data that resides in parallel part and serial part at different orientations, a calibration method has been put forward and proved to be applicable. The precision of the calibrated model mainly depends on the number of measurements carried out. The distribution of measurement points also affects the precision and the measurement number could be significantly reduced if uniform distribution were ensured. 相似文献
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Geometrical work piece errors in milling process are commonly generated by different error sources. Axis geometrical errors, such as the straightness error for linear axis and the offset location error of the origin of rotary axis, introduce kinematic error in the tool path. Direct measurement of kinematic error requires special devices such as laser interferometers, grid plate encoders or double ball bars, which impose production stop and specialized staff. These problems could be analyzed using indirect measurements obtained by means of a cutting performance test that is already a standard for three axis machine tools. Because of the different architectures of five-axis milling machines these tests are hardly standardizable, therefore this paper proposes a devised easy-to-use and time efficient cutting performance test to identify and quantify axis geometrical errors for a five axis tilting-rotary table machine tool. This test can be performed as a periodical checkup or, in case of production, as a re-start test. The main goal of this study is to develop a kinematic analytical model capable of correlating the work-piece geometrical errors to the axis geometrical errors of the machine tool. The model has been implemented on a multi-body software in order to simulate the axes motion sequence of the performance test and validated to decouple the kinematic error into the geometrical axis errors. The developed models have demonstrated to be capable of correcting a generic five axis tool path by predicting the tool-path error displacement. The overall validation of this approach has been carried out by comparing the simulated and experimentally measured profile of the NAS 979 standard five axis contouring cone frustum profile. 相似文献
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Deuk Soo Kang Tae Won Seo Jongwon Kim 《Journal of Mechanical Science and Technology》2008,22(4):746-754
This paper presents a micro-positioning platform based on a unique parallel mechanism developed by the authors. The platform
has a meso-scale rectangular shape whose size is 20 × 23 mm. The stroke is 5 mm for both the x-and y-axes and 100 degrees for the α-axis. The platform is actuated by three sets of dual stage linear actuators: a linear motor for rough positioning and a piezo
actuator for fine positioning. The developed micro-positioning platform has a measurement system that consists of three linear
sensors. The position and orientation values of the movable platform can be measured directly and used in a feedback control
system. Selecting 18 kinematic error parameters of a measurement system (feedback control system), a two-stage kinematic calibration
method is proposed. Constant error parameters are found in the first stage and variable error parameters are found in the
second stage of kinematic calibration. After kinematic calibration the position error is reduced to within 0.5 μm and error
reduction rate is over 90%. 相似文献
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基于6-TPS型并联机床的标定方法研究 总被引:4,自引:0,他引:4
以6-TPS型并联机床为对象,研究了并联机床运动学标定方法。首先假定了并联机床各结构参数单位误差,在与测量方式相一致的广义坐标上,通过并联机床正解的方式,利用所测的点数据,以数值法构造了机床末端位姿误差与结构误差的影响系数矩阵。通过这种方法,构造参数误差数学辨识模型,针对6-TPS型并联机床的特点,提出了测量并联机床平动和聚点性误差的方案,并在工程实际应用中验证了该标定方法的可行性。 相似文献
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Digitization precision analysis is an important tool to ensure the design precision of machine tool currently.The correlative research about precision modeling and analysis mainly focuses on the geometry precision and motion precision of machine tool,and the forming motion precision of workpiece surface.For the machine tool with complex forming motion,there is not accurate corresponding relationship between the existing criterion on precision design and the machining precision of workpiece.Therefore,a design scheme on machine tool precision based on error prediction is proposed,which is divided into two-stage digitization precision analysis crucially.The first stage aims at the technology system to complete the precision distribution and inspection from the workpiece to various component parts of technology system and achieve the total output precision of machine tool under the specified machining precision;the second stage aims at the machine tool system to complete the precision distribution and inspection from the output precision of machine tool to the machine tool components.This article serves YK3610 gear hobber as the example to describe the error model of two systems and basic application method,and the practical cutting precision of this machine tool achieves to 5-4-4 grade.The proposed method can provide reliable guidance to the precision design of machine tool with complex forming motion. 相似文献
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以Stewart型并联机床为对象,研究一种能实现自标定的运动学标定方法,以提高标定效率.在建立两点之间距离误差的基础上,采用哑铃型球杆作为标准的检测量具,并以此建立机床结构参数误差与球杆标准长度之间的误差传递模型.提出了数据自动采集的方案,开发了专用标定软件,实现了数据采集、数据分析处理和机床结构参数补偿的集成.基于提出的方法,利用测头、球杆和为标定而开发的软件,作为加工叶片的Stewart型六自由度并联机床标定的工具.经两次标定,在机床工作空间内,并联机床的运动学定位误差控制在±0.02 mm以内. 相似文献
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热误差严重影响着机床的加工精度,对机床关键部件进行热特性分析是开发精密机床的重要环节。通过测量包括数控机床的特殊位置温度和定位误差在内的热特性,研究了温升与定位误差之间的关系,提出了一种基于贝叶斯神经网络的热误差建模方法。通过K-means聚类和相关系数法来选择温度敏感点,可以有效地抑制温度测量点之间的多重共线性问题。结果表明:通过使用贝叶斯神经网络能提高机床88.015 9%的精度,比BP神经网络高出15.763 8%,与BP神经网络模型相比,贝叶斯神经网络具有更加优良预测性能。贝叶斯神经网络模型为降低机床热误差的影响提供了新思路。 相似文献
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介绍了一种新型立卧转换式三杆混联机床—3-TPS混联机床,对该机床的结构进行了分析。文中给出了该机床在实现立卧转换加工时的坐标变换过程及变换方程,给出了实现立卧转换加工时的后置处理算法及数学模型,并分析了该机床在两种不同加工方式下所能够实现的三轴联动加工、四轴联动加工。文中所给的算法简单、直观、实用,方程为显示。 相似文献
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Evaluating machine tool performance under machining conditions is generally used as the final test in machine tool industry. The seventh part of ISO-10791 describes a machining test using the accuracy of a finished work piece to determine the accuracy of three-axis machine tools. However the kinematic errors cannot be distinguished from each other by means of these test pieces. In this paper a new method to identify the kinematic errors of three-axis machine tool is proposed. A set of test pieces are designed where the kinematic errors of a machine tool can be measured separately along X, Y and Z directions. A volumetric error model is also presented based on the measured errors. This method is initially evaluated in virtual environment and then with some test pieces designed for this purpose. The results are compared with the laser interferometry measurements. It is shown that the measured positioning and straightness errors are consistent with the laser interferometry results. Angular errors measured by the test pieces are also complied with the laser interferometry results as long as the angular error magnitudes are large enough. 相似文献
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Dr Jenq Shyong Chen Cheng Chang Ling 《The International Journal of Advanced Manufacturing Technology》1996,11(3):198-205
Improving both the positioning accuracy and contouring accuracy of a vertical machining centre has been studied by using a machine tool metrology and in-house error correction techniques. Contouring errors caused by the servo lag and friction of servomechanisms were measured by the circular test and then reduced by off-line parameter tuning of the CNC and servo-driver. The quasistatic thermal errors were predicted online using a neural network based model which was calibrated in advance via a quick set-up and multiple-error measurement system consisting of a spindle-mounted probe and artifacts. Positioning errors caused by both the static geometric errors and thermal effects were eliminated in real-time by a PC based software error compensation scheme integrated with the CNC controller through digital communication. An error reduction of 70% was achieved after error compensation and CNC tuning. 相似文献
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基于UG的6-SPS并联机床加工过程仿真 总被引:1,自引:0,他引:1
6 SPS并联机床加工过程仿真系统是在CAD/CAM/CAE集成软件UG基础上利用VisualC 6 0和OpenGL开发的。重点描述图形化仿真模块和后置处理模块 ,并以球冠加工为例 ,验证该加工过程仿真系统的正确性和实用性。 相似文献
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Geometric error calibration of multi-axis machines using an auto-alignment laser interferometer 总被引:6,自引:0,他引:6
This work will report the development and application of an auto-alignment laser interferometer system for the geometric error calibration of CNC multi-axis machines. The system is capable of a diagonal displacement measurement, where multiple machine axes are moved simultaneously, with automatic optic alignment. This capability provides a solution for quick evaluation of the overall volumetric error of a multi-axis machine tool. One application of the system is that the 21 geometric errors of a 3-axis machine can be quickly estimated from the displacement measurements of some determined diagonal lines in the working volume. Compared with a time of several days using a conventional laser interferometer system, it takes only 1 hour for the proposed system to complete the geometry calibration of a 3-axis machine. A method for the roll calibration of a vertical axis is also proposed and demonstrated in this work. 相似文献
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Temperature variable optimization for precision machine tool thermal error compensation on optimal threshold 总被引:1,自引:0,他引:1
Machine tool thermal error is an important reason for poor machining accuracy.Thermal error compensation is a primary technology in accuracy control.To build thermal error model,temperature variables are needed to be divided into several groups on an appropriate threshold.Currently,group threshold value is mainly determined by researchers experience.Few studies focus on group threshold in temperature variable grouping.Since the threshold is important in error compensation,this paper arms to find out an optimal threshold to realize temperature variable optimization in thermal error modeling.Firstly,correlation coefficient is used to express membership grade of temperature variables,and the theory of fuzzy transitive closure is applied to obtain relational matrix of temperature variables.Concepts as compact degree and separable degree are introduced.Then evaluation model of temperature variable clustering is built.The optimal threshold and the best temperature variable clustering can be obtained by setting the maximum value of evaluation model as the objective.Finally,correlation coefficients between temperature variables and thermal error are calculated in order to find out optimum temperature variables for thermal error modeling.An experiment is conducted on a precise horizontal machining center.In experiment,three displacement sensors are used to measure spindle thermal error and twenty-nine temperature sensors are utilized to detect the machining center temperature.Experimental result shows that the new method of temperature variable optimization on optimal threshold successfully worked out a best threshold value interval and chose seven temperature variables from twenty-nine temperature measuring points.The model residual of z direction is within 3 m.Obviously,the proposed new variable optimization method has simple computing process and good modeling accuracy,which is quite fit for thermal error compensation. 相似文献
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通过构建数控机床伺服进给系统的死区误差数学模型,给出齿轮传动、丝杠传动、齿条传动、摩擦力等引起死区误差的数学表达式;探讨减小死区误差的方法;最后综述了减小数控机床伺服进给系统死区误差的一些新措施及今后进一步的工作。 相似文献
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基于改进遗传算法实现柔性三坐标测量机参数标定 总被引:3,自引:3,他引:0
针对柔性三坐标测量机测量精度低的弊端,提出了误差修正和参数标定的方法.应用Denavit-Hartenberg( DH)法建立了柔性三坐标测量系统的运动学模型和误差模型,考虑系统结构参数标定问题,提出了一种基于优化最小二乘法的改进遗传算法.首先,在最小二乘法中引入变化因子来衡量收敛速度;其次,当该因子趋于稳定时,将产生... 相似文献