Investigation of rotary axes geometric performance of a five-axis machine tool using a double ball bar through dual axes coordinated motion

2019 ◽  
Vol 103 (9-12) ◽  
pp. 3943-3952 ◽  
Author(s):  
Xiaogeng Jiang ◽  
Liang Wang ◽  
Chang Liu
Keyword(s):  
Machine Tool ◽  
Coordinated Motion ◽  
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.

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.

Error Calibration for Five-Axis Machine Tools by On-the-Machine Measurement Using a Touch-Trigger Probe

2014 ◽  
Vol 8 (1) ◽  
pp. 20-27 ◽  
Author(s):  
Soichi Ibaraki ◽  
◽  
Yusuke Ota
Keyword(s):  
Machine Tool ◽  
Test Piece ◽  
Machine Tools ◽  
Experimental Demonstration ◽  
Arbitrary Geometry ◽  
Rotary Axes ◽  
Ball Bar ◽  
Touch Trigger Probe ◽  
Error Calibration ◽  
Five Axis

This paper presents a scheme to calibrate the error map of the rotary axes of a five-axis machine tool. This is done by means of on-the-machine measurement of a test piece using a contact-type touch-trigger probe. The present probing-based approach is more suitable for efficient and automated “self-calibration,” than conventional calibration schemes, such as ball bar tests or R-test. It is thus advantageous in the application to periodic checking of the error map, or periodic updating of its numerical compensation. In the present approach, a test piece of arbitrary geometry, e.g. a raw unmachined workpiece, can be used as the probing target. An experimental demonstration is presented.

scholarly journals Ball Bar Measurement on Machine Tools with Rotary Axes

2012 ◽  
Vol 6 (2) ◽  
pp. 180-187 ◽  
Author(s):  
Yukitoshi Ihara ◽  
Keyword(s):  
Machine Tool ◽  
Machine Tools ◽  
Industrial Robots ◽  
Error Sources ◽  
Rotary Axes ◽  
Rotary Axis ◽  
Test Conditions ◽  
Ball Bar ◽  
Articulated Robots ◽  
Five Axis

A ball bar is a very convenient device for measuring the motion accuracy of machine tools. Some trials have also been done for measuring motion accuracy of industrial robots. Nowadays, multi-axis machines such as five-axis machining centers are very popular, and therefore, there is increased demand for checking their accuracy. This paper introduces an idea for checking the motion accuracy of five-axis machining centers and diagnosing error sources by reviewing trial measurements on articulated industrial robots. There are two problems. The first problem is that the ball bar can measure only distances, and the second problem is that the ball bar is a linear device and therefore not suitable for the rotary axis motion of 5-axis machines and articulated robots. Finally, the test conditions for the measurement of the motion accuracy of a machine tool showing conical motion, by using the ball bar and ISO/DIS 10791-6 (which is currently being edited) are reviewed and verified.

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