An identifying method with considering coupling relationship of geometric errors parameters of machine tools

The geometric errors parameters are important for machining accuracy of five-axis machine tool. However, most of the error identification methods only based on the detection instruments to achieve identification of single error parameter, without considering the coupling relationship of these errors between five axes. This paper measures and identifies the position-dependent error parameters and verticality errors of non-orthogonal five-axis machine tools. First, position-dependent error parameters related to the translational axis are measured by the laser interferometer. Next, based on its identification method, the rotary axis is measured in the axial, radial and tangential measurement modes by using a double ball bar. With the measured result, 18 position-dependent errors which related to the motion of linear axis, 6 position-dependent error parameters and 2 verticality errors of axis C and 4 position-dependent error parameters and 1 verticality error of axis B are identified. Finally, the identification results are verified by the compensation of an actual process on the sample of S-shaped piece, whose precise results show that the machining precision increased by 84.2% on average after compensation. Consequently, the measurement and identification method as well as the effectiveness of the compensation method of this paper are verified.