All position-dependent geometric error identification for rotary axes of five-axis machine tool using double ball bar

2020 ◽  
Vol 110 (5-6) ◽  
pp. 1351-1366
Author(s):  
Qingzhao Li ◽  
Wei Wang ◽  
Jing Zhang ◽  
Hai Li
Keyword(s):  
Machine Tool ◽  
Geometric Error ◽  
Error Identification ◽  
Rotary Axes ◽  
Double Ball Bar ◽  
Ball Bar ◽  
Five Axis

Accuracy evaluation of rotary axes of five-axis machine tools with a single setup of a double ball bar

2016 ◽  
Vol 231 (3) ◽  
pp. 427-436 ◽  
Author(s):  
Xiaogeng Jiang ◽  
Robert J Cripps
Keyword(s):  
Machine Tool ◽  
Machine Tools ◽  
Dynamic Performance ◽  
Second Step ◽  
Accuracy Evaluation ◽  
Rotary Axes ◽  
Double Ball Bar ◽  
Ball Bar ◽  
Five Axis ◽  
Rotary Type

A double ball bar (DBB) is used extensively to evaluate the geometric and dynamic performance of three-axis machine tools by means of the XY, YZ and XZ planar circular tests. However, research using a DBB to test the rotary axes of five-axis machine tools simply, quickly and effectively is scarce. In this paper, a method having two steps to identify the imprecision of the rotary axes caused by the position-independent geometric errors (PIGEs) is presented for a tilting rotary type five-axis machine tool using a DBB. The first step is designed to evaluate two rotary axes with one setup. Its advantage of fast diagnosis effectively reduces the machine down time, and thus can be employed as a quick testing approach of the machine tool. However, if some of the diagnosed errors fall outside their tolerances, a more accurate but slower check needs to be carried out due to the limitation of the first step. The second step aims to test the two rotary axes separately, each in two sub-steps. By means of varying the position of the pivot, the A- and C-axes can be tested individually. Both steps are performed with only one axis moving, thus simplifying the error analysis. Implementation of the proposed methods was carried out on a Hermle C600U five-axis machine tool. To show the validity of the method, the identified PIGEs are compensated for in each step, which suggests that the first step can be used as a fast and preliminary indication of a five-axis machine tool’s performance, whilst the second can be carried out if a more thorough evaluation is needed.

scholarly journals A novel geometric error identification methodology for the tilting head of five-axis machine tools based on double ball bar

2018 ◽  
Vol 221 ◽  
pp. 04001
Author(s):  
Jinwei Fan ◽  
Changjun Wu ◽  
Zhongsheng Li
Keyword(s):  
Machine Tools ◽  
Relative Displacement ◽  
Geometric Error ◽  
Body System ◽  
Error Identification ◽  
Double Ball Bar ◽  
Motion Condition ◽  
Ball Bar ◽  
Multi Body ◽  
Five Axis

The paper proposes a novel geometric error identification methodology for the tilting head of five-axis machine tools using double ball bar(DBB).Firstly, based on the motion condition of the tilting head of five-axis machine tools, three measurement patterns in Y direction, X direction and Z direction are proposed respectively. Then, the relative displacement equations of two balls of DBB in three measurement patterns are established respectively on the basis of homogeneous transform matrix (HTM) and multi-body system (MBS) theory. Finally, the geometric error parameters of the tilting head are identified totally. The presented method is universal and provides a reference for the error identification for the tilting head of five-axis machine tools.

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.

An Improvement Geometric Error Identification Method of CNC Machine Tool Based on Double Ball Bar

2014 ◽  
Vol 496-500 ◽  
pp. 1516-1521
Author(s):  
Qiang Cheng ◽  
Zhuo Qi ◽  
Kai Li ◽  
Li Gang Cai ◽  
Dong Lu
Keyword(s):  
Machine Tool ◽  
Recognition Algorithm ◽  
Geometric Error ◽  
Cnc Machine Tools ◽  
Cnc Machine ◽  
Error Identification ◽  
Double Ball Bar ◽  
Ball Bar ◽  
Error Recognition ◽  
Better Than

The double ball bar is widely used because it can quickly, easily and cost-effectively detect and evaluate the accuracy of CNC machine tools. But since the error recognition algorithm based on the double ball bar ignores the quadratic item, its recognition accuracy would be reduced. In this paper, an improved CNC verticality error and position error identification formula, combined with the machine tool error model to deduce a new error recognition model of double ball bar measurement is proposed. It can be drawn that the accuracy of the model are better than the existing methods because it keeps the second item in the derivation process of the model.

A Complete, Continuous, and Minimal Product of Exponentials-Based Model for Five-Axis Machine Tools Calibration With a Single Laser Tracker, an R-Test, or a Double Ball-Bar

2019 ◽  
Vol 141 (4) ◽  
Author(s):  
Peng Xu ◽  
Benny C. F. Cheung ◽  
Bing Li
Keyword(s):  
Machine Tool ◽  
Machine Tools ◽  
Rigid Bodies ◽  
Error Model ◽  
Laser Tracker ◽  
Calibration Model ◽  
Transformation Matrices ◽  
Double Ball Bar ◽  
Ball Bar ◽  
Five Axis

Calibration is an important way to improve and guarantee the accuracy of machine tools. This paper presents a systematic approach for position independent geometric errors (PIGEs) calibration of five-axis machine tools based on the product of exponentials (POE) formula. Instead of using 4 × 4 homogeneous transformation matrices (HTMs), it establishes the error model by transforming the 6 × 1 error vectors of rigid bodies between different frames resorting to 6 × 6 adjoint transformation matrices. A stable and efficient error model for the iterative identification of PIGEs should satisfy the requirements of completeness, continuity, and minimality. Since the POE-based error models for five-axis machine tools calibration are naturally complete and continuous, the key issue is to ensure the minimality by eliminating the redundant parameters. Three kinds of redundant parameters, which are caused by joint symmetry information, tool-workpiece metrology, and incomplete measuring data, are illustrated and explained in a geometrically intuitive way. Hence, a straightforward process is presented to select the complete and minimal set of PIGEs for five-axis machine tools. Based on the established unified and compact error Jacobian matrices, observability analyses which quantitatively describe the identification efficiency are conducted and compared for different kinds of tool tip deviations obtained from several commonly used measuring devices, including the laser tracker, R-test, and double ball-bar. Simulations are conducted on a five-axis machine tool to illustrate the application of the calibration model. The effectiveness of the model is also verified by experiments on a five-axis machine tool by using a double ball-bar.

scholarly journals Geometric Error Identification and Analysis of Rotary Axes on Five-Axis Machine Tool Based on Precision Balls

2019 ◽  
Vol 10 (1) ◽  
pp. 100 ◽  
Author(s):  
Chuandong Li ◽  
Xianli Liu ◽  
Rongyi Li ◽  
Shi Wu ◽  
Houwang Song
Keyword(s):  
Machine Tool ◽  
Error Term ◽  
Geometric Error ◽  
Contact Method ◽  
Error Measurement ◽  
Spatial Error ◽  
Term Operation ◽  
Rotary Axes ◽  
Geometric Error Measurement ◽  
Five Axis

This paper presents the design of a precise “ball-column” device to efficiently and accurately measure the geometric error terms of both rotary axes of the five-axis machine tool. A geometric error measurement method of spherical contact was proposed based on the influence of the geometric error term from a five-axis machine tool rotating axis on the integrated geometric error of the machine tool. A multiple degree of freedom, step-by-step contact method based on on-machine measure for measuring the spherical center point is proposed, and the solution formula of each geometric error term of the rotating axis is established, respectively. This method can identify 12 geometric errors based on the influence of one rotating axis on another rotating axis after long term operation. The spatial error field of the five-axis machine tool was constructed by analyzing the error law of the two rotating axes of machine tools based on various positions and postures. Finally, after the comparison of the experiment, the results showed that the accuracy of the developed error measurement device reached 91.8% and the detection time was as short as 30–40 min.

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.

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