Pivotal errors identification of the face gear worm grinding machine tool with a piecewise sensitivity analysis

As one of the main error sources, geometric errors greatly affect the machining accuracy of the face gear worm grinding machine tool. To reveal the mapping rules between the geometric errors and the tooth surface errors (TSEs) of face gear, the tool comprehensive error model (TCEM) and the tooth surface error model (TSEM) were successively established. The TCEM expressed the relationship between 41 geometric errors of the machine tool and 6 tool comprehensive errors (TCEs) of the tool while the TSEM expressed the relationship between 6 TCEs and 3 TSEs. Then, using the improved Sobol method, a piecewise sensitivity analysis was carried out by calculating the sensitivity indexes of the input of the TCEM and TSEM individually. Finally, the joint sensitivity indexes were calculated and the pivotal geometric errors were identified. By modifying the pivotal geometric errors in each TSE direction separately, all the main error reduction rates (ERR) are greater than 70%. Besides, by modifying all the pivotal geometric errors, the maximum values of 3 TSEs are reduced by 73.7%, 74.7% and 86.96%, respectively, and the minimum values are reduced by 57.1%, 71.79% and 76.19%, respectively, confirming the validity of the identified results.