Optimal proportion compensation method of key geometric errors for five-axis machine tools considering multiple-direction coupling effects

Abstract

Five-axis machine tools are subject to highly coupled geometric errors that significantly affect their machining accuracy. Existing geometric error compensation methods do not consider the coupling effects between errors, resulting in insufficient error compensation efficiency and accuracy. To solve this problem, an optimal proportion compensation method for key geometric errors of five-axis machine tools was proposed, considering multiple direction coupling effects. The key geometric errors were identified using the improved Sobol method based on the volumetric error model. The coupling effects of the geometric errors were analyzed based on the overlapping terms of the key errors in multiple directions, and the coupling situation was classified into four types. The compensation sequence and proportion value in each direction were developed according to the coupling type; i.e., the key errors were compensated to the proportion value instead of the traditional compensation to zero. Taking the S-shaped specimen as an example, the experimental verification indicated that the number of geometric error items that had to be compensated by our method was reduced by 44.4 % compared to the traditional key geometric error compensation method. Additionally, the compensation accuracy was increased by 58.9 %, thus proving the effectiveness of the proposed method.