The Geometric Errors Identification of New Methods in Four-Axis Machining Center Axis

2012 ◽  
Vol 220-223 ◽  
pp. 348-354 ◽  
Author(s):  
Shuan Qiang Yang ◽  
Shu Wen Lin
Keyword(s):  
Geometric Error ◽  
Identification Accuracy ◽  
Geometric Errors ◽  
Sensitivity Matrix ◽  
Error Identification ◽  
Rotary Axes ◽  
Machining Center ◽  
Rational Distribution ◽  
Ball Bar ◽  
Center Axis

A method for fast measuring and identify the six geometric errors of each rotary axes in Four- axis machining center was invented. The method adopted the ball-bar to measure the X, Y, Z direction deviations of the centre block installed on the rotary table in the different rotation angle. And deduced the geometric error identification model in rotary axes based homogeneous transformation, and then identify the axis of the six basic geometric errors. in order to reduce the influence of the inaccuracy of the ball-bar and the reference point position, this paper put forward new method based on the analysis of the sensitivity matrix method, used to guide rational distribution points, so as to improve the error identification accuracy.

The tool following function-based identification approach for all geometric errors of rotary axes using ballbar

2016 ◽  
Vol 230 (19) ◽  
pp. 3509-3527
Author(s):  
Guoqiang Fu ◽  
Jianzhong Fu ◽  
Hongyao Shen ◽  
Xinhua Yao
Keyword(s):  
Least Square Method ◽  
Geometric Error ◽  
Least Square ◽  
Geometric Errors ◽  
Rotary Axes ◽  
Machining Center ◽  
Identification Approach ◽  
Error Formulas ◽  
Five Axis ◽  
Sensitive Direction

This paper proposes a tool following function-based identification approach (TFFIA) for geometric errors of two rotary axes for one five-axis machine tool. It is comprehensive to identify all geometric errors of rotary errors. Firstly, synthetic error formulas of ballbar originate from the geometric error model of machine tools in order to consider the influences of 21 errors of three translational axes. It makes the approach more reasonable and precise. Secondly, the structures of three measurement patterns of TFFIA are described. Thirdly, in each pattern, errors of rotary axes affecting the accuracy of the sensitive direction are identified. As the result, the identification equations of all 20 errors coincide with the geometric properties of errors. Moreover, the impacts of setup errors of ballbar are eliminated with least square method to improve the precise of TFFIA. According to the structures of three patterns, only three installation of workpiece ball of ballbar are needed in the whole identification of two rotary axes to obtain the required ballbar readings. It greatly shortens the measurement time. Twenty geometric errors of two rotary axes are calculated with identification equations and ballbar readings. Finally, TFFIA is applied to a SmartCNC500 five-axis vertical machining center. The corresponding comparisons are proposed to verify the effectiveness and accuracy of TFFIA.

scholarly journals A method for identifying  and predicting the geometric errors of a rotating axis

2020 ◽  
Author(s):  
Jinwei Fan ◽  
Peitong Wang ◽  
Haohao Tao ◽  
Zhongsheng Li ◽  
Jian Yin
Keyword(s):  
Machine Tool ◽  
Prediction Method ◽  
Geometric Error ◽  
Geometric Errors ◽  
Error Identification ◽  
Rotary Axis ◽  
Double Ball Bar ◽  
Ball Bar ◽  
Discrete Values ◽  
Identification Model

Abstract To improve the machine tool accuracy, an integrated geometric error identification and prediction method is proposed to eliminate the positioning inaccuracy of tool ball for a double ball bar (DBB) caused by the rotary axis’ geometric errors in a multi-axis machine tool. In traditional geometric errors identification model based on homogenous transformation matrices (HTM), the elements of position-dependent geometric errors(PDGEs) are defifined in the local frames attached to the axial displacement, which is inconvenient to do redundance analysis. Thus, this paper proposed an integrated geometric error identification and prediction method to solve the uncertainty problem of the PDGEs of rotary axis. First, based on homogeneous transform matrix (HTM) and multi-body system (MBS) theory, The transfer matrix only considering the rotary axes is derived to determine the tool point position error model. Then a geometric errors identification of rotary axis is introduced by measuring the error increment in three directions. Meanwhile the geometric errors of C-axis are described as position-dependent truncated Fourier polynomials caused by fitting discrete values. Thus, The geometric error identification is converted to the function coefficient. Finally, the proposed new prediction and identification model of PDGEs in the global frame are verified through simulation and experiments with double ball-bar tests.

scholarly journals New identification method for computer numerical control geometric errors

2021 ◽  
pp. 002029402110108
Author(s):  
Hongtao Yang ◽  
Mei Shen ◽  
Li Li ◽  
Yu Zhang ◽  
Qun Ma ◽  
...  
Keyword(s):  
Machine Tools ◽  
Geometric Error ◽  
Numerical Control ◽  
Identification Accuracy ◽  
Cnc Machine Tools ◽  
Geometric Errors ◽  
Cnc Machine ◽  
Identification Method ◽  
Double Ball Bar ◽  
Ball Bar

To address the problems of the low accuracy of geometric error identification and incomplete identification results of the linear axis detection of computer numerical control (CNC) machine tools, a new 21-item geometric error identification method based on double ball-bar measurement was proposed. The model between the double ball-bar reading and the geometric error term in each plane was obtained according to the three-plane arc trajectory measurement. The mathematical model of geometric error components of CNC machine tools is established, and the error fitting coefficients are solved through the beetle antennae search particle swarm optimization (BAS–PSO) algorithm, in which 21 geometric errors, including roll angle errors, were identified. Experiments were performed to compare the optimization effect of the BAS–PSO and PSO and BAS and genetic particle swarm optimization (GA–PSO) algorithms. Experimental results show that the PSO algorithm is trapped in the local optimum, and the BAS–PSO is superior to the other three algorithms in terms of convergence speed and stability, has higher identification accuracy, has better optimization performance, and is suitable for identifying the geometric error coefficient of CNC machine tools. The accuracy and validity of the identification results are verified by the comparison with the results of the individual geometric errors detected through laser interferometer experiments. The identification accuracy of the double ball-bar is below 2.7 µm. The proposed identification method is inexpensive, has a short processing time, is easy to operate, and possesses a reference value for the identification and compensation of the linear axes of machine tools.

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.

Feasibility Study of Using Simultaneous Motion of Two Rotary Axes to Evaluate Machining Center: Simulation

2011 ◽  
Author(s):  
K. M. Muditha Dassanayake ◽  
Masaomi Tsutsumi ◽  
Ohta Katsunori
Keyword(s):  
Mathematical Model ◽  
Feasibility Study ◽  
Radial Direction ◽  
Rotary Table ◽  
Measuring Device ◽  
Rotary Axes ◽  
Machining Center ◽  
Double Ball Bar ◽  
Ball Bar ◽  
The Mathematical Model

In this paper, a new motion: the two rotary axes simultaneous motion was proposed and the mathematical model which was used to carryout simulations was described. The effect of each deviation on the proposed motion was identified and described one by one. A methodology to estimate all the eight deviations which inherent to tilting rotary table type machining centers was described step by step. This methodology consists of two motions: the proposed motion and C axis radial direction motion. Both the two motions used only the rotary axes. All the motions can be run on one setup. The simulations were carried out by considering that the double ball bar as the measuring device. Furthermore, number of settings which can be used for the new motion were discussed. From this study, it was confirmed that this method can be used for estimate all the eight deviations, accurately.

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.

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.

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.

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