Sensitivity analysis of machining accuracy of multi-axis machine tool based on POE screw theory and Morris method

Abstract

The geometric errors have a significant effect on the machining accuracy of multi-axis machine tool. Because of their complex inter-coupling, the process to control these geometric errors and then to improve the machining accuracy on this basis is recognized as a difficult problem. This paper proposes a method based on the product of exponential (POE) screw theory and Morris approach for volumetric machining accuracy global sensitivity analysis of a machine tool. When a five-axis machine tool is chosen as an example, there are five screws to represent the six basic error components of each axis (in an original way) according to the geometric definition of the errors and screws. This type of POE model is precise and succinct enough to express the relation of each of the components as the Morris method is based on the elementary effect (EE). The method can compare incidence of these errors and be used to describe the nonlinear relationship by less calculated amount in a global system. Based on the POE modelling, the Morris method is adopted to identify the key geometric errors which have a greater influence on the machining accuracy by global sensitivity analysis. Finally, according to the results obtained from analysis, suggestions, and guidelines are provided to adjust and modify the machine tool components to improve the machining accuracy economically.