Study on the spindle axial thermal error of a five-axis machining center considering the thermal bending effect

Spindle axial thermal error is one of the main sources affecting the accuracy of a machine tool. It is important to study this error with respect to thermal optimization design and thermal error compensation. The column thermal bending effect mainly caused by spindle rotating is an important factor affecting the spindle axial thermal error, but it is often ignored in current research. In this paper, a novel modeling approach to studying the spindle axial thermal error of a five-axis machining center that considers the thermal bending effect was proposed. Experiments with different thermal boundary conditions were conducted to decouple this error. The thermal deformation coefficients of the column were effectively identified by using both the axial and radial thermal error data. Then, a physically-based model including the error component caused by the thermal bending effect was established. The complicated evolution process of the measured spindle axial thermal error can be explained by the proposed model. The thermal bending angles can be also effectively predicted to quantify the thermal bending behaviors. Furthermore, compared with three typical data-driven models, the proposed model shows better performance in predicting the axial thermal error. The proposed modeling method helps in better revealing the formation mechanism of the spindle axial thermal error. And the proposed model shows a good application prospect for error compensation because of its generalization ability and simplicity.