Robust measurement method and uncertainty analysis for position-independent geometric errors of a rotary axis using a double ball-bar

2013 ◽  
Vol 14 (2) ◽  
pp. 231-239 ◽  
Author(s):  
Kwang-Il Lee ◽  
Seung-Han Yang
Keyword(s):  
Uncertainty Analysis ◽  
Measurement Method ◽  
Geometric Errors ◽  
Rotary Axis ◽  
Double Ball Bar ◽  
Ball Bar

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.

A New and High Precision Measurement Method of Spindle Rotation Induced Error and its Performance Research

2007 ◽  
Vol 10-12 ◽  
pp. 727-731 ◽  
Author(s):  
Z.C. Du ◽  
P. Zhang ◽  
Jian Guo Yang ◽  
M.S. Hong
Keyword(s):  
Frequency Domain ◽  
Measurement Method ◽  
Cnc Machine ◽  
Motion Error ◽  
Machining Center ◽  
Double Ball Bar ◽  
Spindle Rotation ◽  
Ball Bar ◽  
Measuring Experiment ◽  
The Cross

The accuracy of spindle rotation is one of the most important precision indexes of CNC machine tools. And the spindle rotation induced error is one of the main influence factors of cutting accuracy. It will greatly affect the shape precision and surface roughness of workpiece. A new measurement method of the spindle radial rotation induced error is proposed using the cross grid encoder. The Spindle rotation induced error of machining center is analyzed in frequency domain and time-frequency domain separately to comparably study the measurement results by KGM 182 grid encoder and Double ball bar. The results indicate that the performance of the cross grid encoder test for measuring the CNC machine tool motion error is better than that of the Double ball bar, especially in the details of motion errors because of its unique characteristics. A wavelet packet algorithm is developed to analyze the singularity of signal. On machine measuring experiment has been carried out on a new Cincinnati 750 Arrow II vertical machining center. The measuring experiment result shows that the spindle radial rotation induced error of the machining center is about 0.6 μm and the cycle time is every rotation time.

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