scholarly journals Error Modeling and Sensitivity Analysis of a Five-Axis Machine Tool

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Wenjie Tian ◽  
Weiguo Gao ◽  
Wenfen Chang ◽  
Yingxin Nie
Keyword(s):  
Sensitivity Analysis ◽  
Machine Tool ◽  
Screw Theory ◽  
Geometric Error ◽  
Error Modeling ◽  
Analysis Method ◽  
Precision Design ◽  
Sensitivity Analysis Method ◽  
Source Errors ◽  
Five Axis

Geometric error modeling and its sensitivity analysis are carried out in this paper, which is helpful for precision design of machine tools. Screw theory and rigid body kinematics are used to establish the error model of an RRTTT-type five-axis machine tool, which enables the source errors affecting the compensable and uncompensable pose accuracy of the machine tool to be explicitly separated, thereby providing designers and/or field engineers with an informative guideline for the accuracy improvement by suitable measures, that is, component tolerancing in design, manufacturing, and assembly processes, and error compensation. The sensitivity analysis method is proposed, and the sensitivities of compensable and uncompensable pose accuracies are analyzed. The analysis results will be used for the precision design of the machine tool.

Sensitivity Analysis of Geometric Errors for Five-Axis CNC Machine Tool Based on Multi-Body System Theory

2012 ◽  
Vol 271-272 ◽  
pp. 493-497
Author(s):  
Wei Qing Wang ◽  
Huan Qin Wu
Keyword(s):  
System Theory ◽  
Sensitivity Analysis ◽  
Machine Tool ◽  
Geometric Error ◽  
Machining Accuracy ◽  
Geometric Errors ◽  
Body System ◽  
Cnc Machine ◽  
Multi Body ◽  
Five Axis

Abstract: In order to determine that the effect of geometric error to the machining accuracy is an important premise for the error compensation, a sensitivity analysis method of geometric error is presented based on multi-body system theory in this paper. An accuracy model of five-axis machine tool is established based on multi-body system theory, and with 37 geometric errors obtained through experimental verification, key error sources affecting the machining accuracy are finally identified by sensitivity analysis. The analysis result shows that the presented method can identify the important geometric errors having large influence on volumetric error of machine tool and is of help to improve the accuracy of machine tool economically.

Modified Jacobian-Torsor Based Error Modeling and Quantitative Sensitivity Analysis for Single Axis Assembly of Machine Tool

2017 ◽  
Author(s):  
Zhengchun Du ◽  
Jian Wu ◽  
Jianguo Yang
Keyword(s):  
Sensitivity Analysis ◽  
Machine Tool ◽  
Error Modeling ◽  
Small Displacement ◽  
Cnc Machine ◽  
Statistical Solution ◽  
Mechanical Parts ◽  
Comprehensive Method ◽  
Precision Design ◽  
Final Error

The influence of component errors on the final error is a key aspect of error modeling of CNC machine tool. Nevertheless, the mechanism by which the errors in mechanical parts accumulate to result in the component errors and then impact the final error of CNC machine, has not been identified; the identification of this mechanism is highly relevant to precision design of CNC machine. In this study, error modeling based on the Jacobian-torsor theory is founded to determine the mechanism by which fundamental errors in mechanical parts influence the comprehensive error of single-axis assembly. Firstly, the constraints of small displacement torsors (SDTs) for typical features and the statistical solution are proposed to perfect the modified Jacobian-torsor model theoretically. Next, the modified Jacobian-torsor model is applied to the error modeling of a single-axis assembly in a three-axis machine center. Furthermore, the comprehensive errors of the single-axis assembly are evaluated by Monte Carlo simulation based on the synthesized error model. The accuracy and efficiency of the modified Jacobian-torsor model are verified through a comparison between the simulation results and the measured data from a batch of similar vertical machine centers. Based on the modified Jacobian-torsor model, the application of quantitative sensitivity analysis of single-axis assembly is investigated, along with an analysis of the analysis of key error sources to the synthetical error ranges of the single-axis assembly. This model is providing a comprehensive method for the better understanding of the key error source of the machine tool and has the potential to enable error allocation and precision improvement of the assembly and the whole machine tool in future.

Accuracy design of high precision machine tools using error sensitivity analysis methodology

2016 ◽  
Vol 231 (18) ◽  
pp. 3401-3413 ◽  
Author(s):  
Wenjie Tian ◽  
Shaopeng Liu ◽  
Xingxing Liu
Keyword(s):  
Sensitivity Analysis ◽  
Machine Tool ◽  
Machine Tools ◽  
Geometric Error ◽  
Sensitivity Index ◽  
Assembly Accuracy ◽  
Machining Test ◽  
Precision Machine Tools ◽  
Design And Manufacture ◽  
Source Errors

Geometric accuracy is a crucially important performance factor for machine tools. Theoretically, the effects of source errors on pose accuracy (positional and angular accuracy) of 3-, 4- or 5-axis machine tools cannot fully be compensated by software, and only those pose errors associated with the permission motions are compensatable by means of error compensation. Therefore, the uncompensatable pose errors should be strictly guaranteed in the processes of design and manufacture. In this paper, after the geometric error model is established, the source errors affecting the uncompensatable pose accuracy are identified out of all the source errors. In order to enhance the understanding of which source errors have more influences on the pose accuracy, a probabilistic sensitivity analysis method is proposed, and the global sensitivity index is defined to evaluate the influence in the overall workspace. According to the sensitivity analysis results, the uncompensatable pose accuracy index is allocated to each source error. And then, assembly accuracy acceptance criteria are proposed as a guideline for machine assemblers. As an application example, the presented approaches are applied to the accuracy design and manufacture of a 4-axis machine tool, and double ball bar measurement and machining test are carried out to check the accuracy of the designed machine tool.

Error modeling and sensitivity analysis of a novel 5-degree-of-freedom parallel kinematic machine tool

2018 ◽  
Vol 233 (6) ◽  
pp. 1637-1652 ◽  
Author(s):  
Xuan Luo ◽  
Fugui Xie ◽  
Xin-Jun Liu ◽  
Jie Li
Keyword(s):  
Sensitivity Analysis ◽  
Machine Tool ◽  
Jacobian Matrix ◽  
Error Modeling ◽  
Degree Of Freedom ◽  
Geometric Errors ◽  
Parallel Kinematic Machine ◽  
Parallel Kinematic ◽  
Position And Orientation ◽  
Five Axis

5-Degree-of-freedom parallel kinematic machine tools are always attractive in manufacturing industry due to the ability of five-axis machining with high stiffness/mass ratio and flexibility. In this article, error modeling and sensitivity analysis of a novel 5-degree-of-freedom parallel kinematic machine tool are discussed for its accuracy issues. An error modeling method based on screw theory is applied to each limb, and then the error model of the parallel kinematic machine tool is established and the error mapping Jacobian matrix of 53 geometric errors is derived. Considering that geometric errors exert both impacts on value and direction of the end-effector’s pose error, a set of sensitivity indices and an easy routine for sensitivity analysis are proposed according to the error mapping Jacobian matrix. On this basis, 10 vital errors and 10 trivial errors are identified over the prescribed workspace. To validate the effects of sensitivity analysis, several numerical simulations of accuracy design are conducted, and three-dimensional model assemblies with relevant geometric errors are established as well. The simulations exhibit maximal −0.10% and 0.34% improvements of the position and orientation errors, respectively, after modifying 10 trivial errors, while minimal 65.56% and 55.17% improvements of the position and orientation errors, respectively, after modifying 10 vital errors. Besides the assembly reveals an output pose error of (0.0134 mm, 0.0020 rad) with only trivial errors, while (2.0338 mm, 0.0048 rad) with only vital errors. In consequence, both results of simulations and assemblies validate the correctness of the sensitivity analysis. Moreover, this procedure can be extended to any other parallel kinematic mechanisms easily.

Sensitivity Analysis of Temperature Measuring Points for Machine Tool Spindle Based on Grey System Theory

2014 ◽  
Vol 800-801 ◽  
pp. 720-725 ◽  
Author(s):  
Qian Feng Wang ◽  
Song Zhang ◽  
Yan Chen ◽  
Qing Zhang ◽  
Bin Zhao
Keyword(s):  
System Theory ◽  
Sensitivity Analysis ◽  
Machine Tool ◽  
Grey System Theory ◽  
Analysis Method ◽  
Grey System ◽  
Measuring Point ◽  
Temperature Measuring ◽  
Machine Tool Spindle ◽  
Sensitivity Analysis Method

This paper presents a sensitivity analysis method of temperature measuring point of the machine tool spindle based on grey system theory. The initial finite element analysis (FEA) is conducted on the spindle model to determine the temperature distribution of the spindle model and ascertain the resultant structural deformation, and eight nodes of the spindle model are selected as temperature measuring points. By means of grey system theory, temperature measuring points of machine tool spindle model are analyzed and then the effects of the different temperature measuring point on the spindle axial deformation are conducted. Finally, the validity of this sensitivity analysis method is verified by conducting the theoretical analysis and developing the linear estimate equation. The analysis results show that this sensitivity analysis method can effectively determine the thermal sensitivity of temperature measuring points, ensure the accuracy of the thermal compensation model and eliminate the coupling problems.

Geometric Error Modeling and Sensitivity Analysis of Single-Axis Assembly in Three-Axis Vertical Machine Center Based on Jacobian-Torsor Model

2017 ◽  
Vol 4 (3) ◽  
Author(s):  
Du Zhengchun ◽  
Wu Jian ◽  
Yang Jianguo
Keyword(s):  
Sensitivity Analysis ◽  
Machine Tool ◽  
Geometric Error ◽  
Error Modeling ◽  
Numerical Control ◽  
Cnc Machine Tool ◽  
Cnc Machine ◽  
Machine Center ◽  
Mechanical Parts ◽  
Final Error

The influence of component errors on the final error is a key point of error modeling of computer numerical control (CNC) machine tool. Nevertheless, the mechanism by which the errors in mechanical parts accumulate to result in the component errors and then impact the final error of CNC machine tool has not been identified; the identification of this mechanism is highly relevant to precision design of CNC machine. In this study, the error modeling based on the Jacobian-torsor theory is applied to determine how the fundamental errors in mechanical parts influence and accumulate to the comprehensive error of single-axis assembly. First, a brief introduction of the Jacobian-torsor theory is provided. Next, the Jacobian-torsor model is applied to the error modeling of a single-axis assembly in a three-axis machine center. Furthermore, the comprehensive errors of the single-axis assembly are evaluated by Monte Carlo simulation based on the synthesized error model. The accuracy and efficiency of the Jacobian-torsor model are verified through a comparison between the simulation results and the measured data from a batch of similar vertical machine centers. Based on the Jacobian-torsor model, the application of quantitative sensitivity analysis of single-axis assembly is investigated, along with the analysis of key error sources to the synthetical error ranges of the single-axis assembly. This model provides a comprehensive method to identify the key error source of the single-axis assembly and has the potential to enhance the tolerance/error allocation of the single axis and the whole machine tool.

Modeling Quasi-Static Errors in a Five-Axis Gantry Machine Tool

2012 ◽  
Vol 152-154 ◽  
pp. 781-787
Author(s):  
Jian Yin ◽  
Ming Li ◽  
Fang Yu Pan
Keyword(s):  
Machine Tool ◽  
Thermal Error ◽  
Geometric Error ◽  
Error Model ◽  
Error Modeling ◽  
Compensation Scheme ◽  
Homogeneous Transformation Matrix ◽  
Body Kinematic ◽  
Five Axis ◽  
Gantry Machine Tool

Enhancing the accuracy of machine tool is a key goal of machine tool manufactures and users. To characterize the Quasi-static errors and then use software compensation is an important step for accuracy enhancement. The effectiveness of an error compensation scheme relies heavily on the error model. The model must be concise and roust which can be applied to any machine tool. The total Quasi-static errors within the workspace of a five-axis gantry machine tool is composed of geometric error, kinematic error, thermal error. This paper presents an error model which can be used for practical compensation scheme. Homogeneous transformation matrix, rigid body kinematic and small angle approximations are used in this paper for error modeling.

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