Geometric Error Identification of a Three-Axis Machining Center

2013 ◽  
Vol 694-697 ◽  
pp. 1803-1807
Author(s):  
Gui Qiang Liang ◽  
Jun Xian Zhang ◽  
Fei Fei Zhao
Keyword(s):  
Working Conditions ◽  
Laser Interferometer ◽  
Great Influence ◽  
Geometric Error ◽  
Machining Accuracy ◽  
Geometric Errors ◽  
Positioning Errors ◽  
Machining Center ◽  
Influence Effect ◽  
Squareness Errors

Geometric errors of a machining center can cause great influence on machining accuracy, and these geometric errors should be identified and compensated in the actual working conditions. Taking a three-axis vertical machining center as example, 21 geometric errors of the machine tool were solved. By using the 12-line method based on a laser interferometer, identification principle of the positioning errors, straightness errors, pitch errors, yaw errors, roll errors and squareness errors are presented, and all of the 21 geometric errors of the machining center were identified. Geometric errors having great influence effect on machining accuracy can be identified. The research results provide guidance for analyze of geometric errors of machining center.

The Effect of Geometric Error on Machining Accuracy for Machining Center

2013 ◽  
Vol 690-693 ◽  
pp. 3244-3248
Author(s):  
Gui Qiang Liang ◽  
Ai Rong Zhang ◽  
Ting Ting Guo
Keyword(s):  
Great Influence ◽  
Geometric Error ◽  
Linear Displacement ◽  
Machining Accuracy ◽  
Geometric Errors ◽  
Lower Body ◽  
Body System ◽  
Research Results ◽  
Machining Center ◽  
Multi Body

In order to improve machining accuracy of machining center, the effect of geometric error on machining accuracy was researched by multi-body system theory. Taking a vertical machining center as example, topological structure of the machining center was described by lower body array. Geometric errors of the bodies in the multi-body system were expressed by homogeneous coordinate transformation. Error model for machining accuracy was deduced and geometric errors having great influence on the machining accuracy were identified. The research results show that, straightness errors and linear displacement errors in three directions have direct influence on machining accuracy, and the effect on machining accuracy caused by angle errors are related to the dimensions of the machining center and travel distance of the three axes. The research results provide guidance for analysis on sensitivity of geometric errors.

Geometric Errors Sensitivity Analysis of Precision Vertical Machining Center Based on Multi-Body System Theory

2011 ◽  
Vol 108 ◽  
pp. 61-66 ◽  
Author(s):  
Qiang Cheng ◽  
Dong Sheng Xuan ◽  
Jie Sun ◽  
Zhi Feng Liu
Keyword(s):  
System Theory ◽  
Sensitivity Analysis ◽  
Machine Tool ◽  
Great Influence ◽  
Geometric Error ◽  
Machining Accuracy ◽  
Geometric Errors ◽  
Body System ◽  
Machining Center ◽  
Multi Body

Parts of geometric error coupled into space error is the main reason that affects machining accuracy of machine tools; therefore, how to determine the effect of geometric error to the machining accuracy and then assigning geometry precision of parts economically is a difficult problem in machine tool designing process. Therefore, based on multi-body system theory, a sensitivity analysis method of geometric error is put forward in this paper. Let’s take precision vertical machining center for an example. Firstly, an accuracy model of machining center is established based on multi-body system theory, and with 21 geometric errors obtained through experimental verification, key error sources affecting the machining accuracy are finally identified by sensitivity analysis. The example analysis shows that the proposed method can effectively identify the main geometric errors of parts that have great influence on volumetric error of machine tool, and thus provides important theoretical basis to improve the accuracy of machine tool economically.

Measuring and Modeling of Volumetric Errors for Vertical Machining Centers Based on Bi-Directional Laser Sequential Step Diagonal Measurement

2018 ◽  
Author(s):  
Huimin Li ◽  
Sitong Xiang ◽  
Ming Deng ◽  
Mengrui Zhu ◽  
Zhengchun Du ◽  
...  
Keyword(s):  
Experimental Tests ◽  
Measuring Method ◽  
Geometric Errors ◽  
Machine Accuracy ◽  
Volumetric Error ◽  
Positioning Errors ◽  
Machining Center ◽  
Direct Measurements ◽  
Volumetric Errors ◽  
Squareness Errors

This paper proposes a bi-directional laser sequential step diagonal measuring method for three-axis vertical machining centers. Different measure paths are particularly designed for positive and negative directions, and corresponding error decoupling models are established. Based on the laser measuring data along these bi-directional paths, 18 geometric errors can be identified simultaneously, including 6 angular errors, 3 positioning errors, 6 straightness errors and 3 squareness errors. Compared with single directional step diagonal measurements, the proposed bi-directional mothed is more efficient and can identify more error items, namely 6 angular errors. Experimental tests were conducted on a three-axis vertical machining center. Decoupled error items obtained by the proposed bi-direction measurements coincide with those from direct measurements via a laser Doppler displacement meter, which verified the feasibility of the proposed method. Finally, the position error of the machine whole workspace was predicted by building volumetric error model and the machine accuracy was improved.

Geometric Error Modeling of a Vertical Machining Center

2013 ◽  
Vol 694-697 ◽  
pp. 1842-1845
Author(s):  
Gui Qiang Liang ◽  
Jun Xian Zhang ◽  
Fei Fei Zhao
Keyword(s):  
Coordinate Transformation ◽  
Transformation Method ◽  
Geometric Error ◽  
Error Modeling ◽  
Machining Accuracy ◽  
Geometric Errors ◽  
Lower Body ◽  
Body System ◽  
Machining Center ◽  
Multi Body

The effect of geometric error on machining accuracy was researched by multi-body system theory, as well as homogeneous coordinate transformation method. Taking a vertical machining center as example, topological structure of the machine tool was described by lower body array. Lower body array of the machining center, motion freedom between adjacent bodies and geometric errors of the vertical machining center were analyzed. Geometric errors of the bodies in the multi-body system were expressed by homogeneous coordinate transformation. Error model for machining accuracy was deduced and geometric errors having influence on the machining accuracy were identified. The research results provide guidance for analyze of geometric errors on machining accuracy.

Influence of NC Program Quality and Geometric Errors Onto S-Shape Machining Accuracy

2018 ◽  
Author(s):  
Ryuta Sato ◽  
Keiichi Shirase ◽  
Yukitoshi Ihara
Keyword(s):  
Great Influence ◽  
Geometric Error ◽  
Machining Accuracy ◽  
Geometric Errors ◽  
Machined Surface ◽  
Nc Program ◽  
Finished Surface ◽  
Machining Test ◽  
Five Axis

S-shaped machining test is proposed for ISO standard to evaluate the motion accuracy of five-axis machining centers. However, it have not been investigated that which factor mainly influences the quality of the finished S-shape workpieces. This study focuses on the influence of the quality of NC program and geometric errors of rotary axes onto the quality of finished surface. Actual cutting tests and simulations are carried out to the investigation. As the results, it is clarified that the tolerance of NC program has a great influence onto the quality. It is also clarified that the geometric errors have great influences onto the quality. However, it is difficult to evaluate the influence of each geometric error because all geometric errors make glitches at the same point on the machined surface. It can be concluded that the proposed S-shape machining test can be used as the total demonstration of the machining techniques.

Modeling and Identification of Geometric Error Based on Screw Theory

2014 ◽  
Vol 941-944 ◽  
pp. 2219-2223 ◽  
Author(s):  
Guo Juan Zhao ◽  
Lei Zhang ◽  
Shi Jun Ji ◽  
Xin Wang
Keyword(s):  
Machine Tool ◽  
Laser Interferometer ◽  
Screw Theory ◽  
Geometric Error ◽  
New Method ◽  
Geometric Errors ◽  
Volumetric Error ◽  
B Spline ◽  
The Individual

In this paper, a new method is presented for the identification of machine tool component errors. Firstly, the Non-Uniform Rational B-spline (NURBS) is established to represent the geometric component errors. The individual geometric errors of the motion parts are measured by laser interferometer. Then, the volumetric error for a machine tool with three motion parts is modeled based on the screw theory. Finally, the simulations and experiments are conducted to confirm the validity of the proposed method.

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.

Positioning Error Compensation for Machining Center Based on Spline Interpolation

2012 ◽  
Vol 472-475 ◽  
pp. 3029-3034
Author(s):  
Peng Li ◽  
Ying Hu ◽  
Zi Ma
Keyword(s):  
Error Compensation ◽  
Laser Interferometer ◽  
Spline Interpolation ◽  
Machining Process ◽  
Accuracy Evaluation ◽  
Positioning Error ◽  
Positioning Errors ◽  
Machining Center ◽  
Compensation Function ◽  
Manual Correction

Related to the machining precision, especially for the middle and low end machining center, the positioning error is often considered as a major factor, which can be traditionally decreased by the pitch compensation function integrated in the CNC system. However, the function is just founded on that all of positioning errors remain constant in the machining process, and it is difficulty to meet the compensation needs in different machining condition. At the same time, it involves a mass of parameters that need professional manual correction. Therefore, the software error compensation method is put forward. Firstly, based on cubic spline interpolation, the error compensation model is designed through the processing of positioning error which is collected by the laser interferometer. Secondly, with the characteristics of G codes, the database is established for error compensation, which can effectively correct different machining G codes with enough error information. Finally, by the experiment and accuracy evaluation, results show that after the positioning error of machining center is compensated by the presented scheme, its precision is improved obviously.

scholarly journals A geometric error tracing method based on the Monte Carlo theory of the five-axis gantry machining center

2017 ◽  
Vol 9 (7) ◽  
pp. 168781401770764 ◽  
Author(s):  
Jinwei Fan ◽  
Yuhang Tang ◽  
Dongju Chen ◽  
Changjun Wu
Keyword(s):  
Monte Carlo ◽  
Machine Tool ◽  
Test Piece ◽  
Great Influence ◽  
Numerical Control ◽  
Geometric Errors ◽  
Machining Center ◽  
Machining Errors ◽  
Five Axis ◽  
Tracing Method

This article proposes a tracing method to identify key geometric errors for a computer numerical control machine tool by cutting an S-shaped test piece. Adjacent part relationships and machine tool errors transform relationships are described by topology of the machining center. Global sensitivity analysis method based on quasi-Monte Carlo was used to analyze machining errors. Using this method, key geometric errors with significant influence on machining errors were obtained. Compensation of the key errors was used to experimentally improve machining errors for the S-shaped test piece. This method fundamentally determines the inherent connection and influence between geometric errors and machining errors. Key geometric errors that have great influence on machining errors can be determined quickly with this method. Thus, the proposed tracing method could provide effective guidance for the design and use of machine tools.

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