Research on static error identification of three-axis machine tool based on multi-flexible system theory

Abstract

In order to comprehensively consider the influence of geometric error caused by manufacturing defects and elastic error caused by the gravity of structural components on the static accuracy of machine tools, as well as the coupling relationship between them, this paper proposes an identification method of static error of three-axis machine tools. Taking the three-axis machine tool as the research object, the static error model of the machine tool is established according to the multi-flexible system theory and the homogeneous transformation matrix (HTM), and the geometric error component and the elastic error component in the static error are qualitatively analyzed. The Chebyshev polynomials are used to establish the parametric model of static error. Based on the three-axis linkage experiment of the Double ball bar (DBB), all the static errors are decoupled. Then, the finite element method is used to discretize the machine tool into three subsystems. Based on the spatial beam element, the stiffness model of each subsystem is established, and the elastic error component in the static error is quantitatively analyzed. The results show that the elastic error affected by gravity is mainly reflected in seven straightness errors and angle errors, and is generally greater than the corresponding static error. It shows that the machine tool offsets the influence of geometric errors from the perspective of elastomer compensation in the design stage, and proposes a simplified static error model of the machine tool.