Modeling and compensation of comprehensive errors for thin-walled parts machining based on on-machine measurement

Thin-walled parts are widely applied in the automotive and aerospace industry for their superior properties. However, severe machining error may occur due to their low rigidity under the effects of multiple error sources in the machining process. Solutions based on mechanism analysis and finite element method have been developed while most of them are not robust under the complex machining conditions. Aiming to solve this problem, a comprehensive error compensation method that includes three major error sources, which are geometric error, thermal error, and force-induced error, is proposed. The geometric error and thermal-induced error of the machining center are firstly modeled and compensated to provide a high precision movement system for the on-machine measurement inspection. The force-induced error model is then established based on the probing data. Finally, the comprehensive error model is obtained through the transformation of the coordinate systems. Besides, a real-time compensation system is developed based on the specific functions of the NC system. To validate the proposed method, two sets of compensation cases are conducted, the objects of which are a thin web workpiece and a valve body part, respectively. The experiment results reveal that the machining errors of both experiment sets are decreased by more than 60.7% and the machining productivity is improved by more than 41.9%.