A Fiducial-Aided Reconfigurable Artefact for the Estimation of Volumetric Errors of Multi-Axis Ultra-Precision Machine Tools

Shixiang Wang,Chifai Cheung,Lingbao Kong

doi:10.3390/app12041824

Shixiang Wang, Chifai Cheung + Show 1 more

Open Access

https://doi.org/10.3390/app12041824

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Abstract

In this paper, a fiducial-aided reconfigurable artefact is presented for estimating volumetric errors of multi-axis machine tools. The artefact makes use of an adjustable number of standard balls as fiducials to build a 3D artefact which has been calibrated on a coordinate measuring machine (CMM). This 3D artefact demonstrates its reconfigurability in its number of fiducials and their locations according to the characteristics of workpieces and machine tools. The developed kinematics of the machine tool were employed to identify the volumetric errors occupied by the workpiece in the working space by comparing the information acquired by on-machine metrology with that acquired by the CMM. Experimental studies are conducted on a five-axis ultra-precision machine tool. A developed 3D artefact composed of five standard spheres is measured by the integrated on-machine measurement system. Factors including the gravity effect and measurement repeatability are also examined in order to optimize the geometry of the artefact. The results show that the developed 3D artefact is able to provide information about the working space occupied by the workpiece.

Highlights

Multi-axis machine tools are key equipment in advanced industries for manufacturing complex freeform components, especially in the fields of ultra-precision diamond turning and polishing
The 3D artefact allows flexibility in the number and position of the fiducials according to the characteristics of the machine tool
A detailed analysis of the effect of deflection due to gravity by tilting the artefact from a horizontal into a vertical orientation indicates that the stable orientation of the artefact and the length of connecting fiducial components which is as short as 25 mm can further reduce the errors of the artefact to lower than 0.8 μm

Summary

Introduction

Multi-axis machine tools are key equipment in advanced industries for manufacturing complex freeform components, especially in the fields of ultra-precision diamond turning and polishing. The accuracy of the workpiece is significantly influenced by the geometric error of these machines. These errors have integrated effects in the manufacture of the products. The modeling and measurement of these volumetric errors are of prime importance in high precision machine tools. It is recommended to regularly verify the accuracy of machine tools [1,2]. In order to improve the machining accuracy and efficiency, many approaches have been reported to measure and compensate for the geometric error [2,3,4]

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