Machining accuracy reliability optimization of three-axis CNC machine tools using doubly-weighted vector projection response surface method

Abstract

Abstract The reasonable allocation of geometric errors of NC machine tools can improve the machining accuracy reliability. However, due to the complexity and high nonlinearity of limit state function (LSF) of machining accuracy reliability, the fitting accuracy is usually low when the traditional method is used to approximate LSF. To solve this problem, a doubly-weighted vector projection response surface (DWVPRS) method, which considers not only the approximation results of the test sample point to LSF but the distance between the test sample point and the most probable failure point (MPFP), is proposed. Using the reliability sensitivity analysis method, the key geometric errors were identified and optimized to meet the design requirements. Finally, taking a large gantry guideway grinding machine as an example to verifies the correctness and effectiveness of the DWVPRS method proposed in this paper, the results show that after the optimization of geometric accuracy, the minimum and average reliability value of the grinding machine meet the design requirements.