Thermal–mechanical coupling model-based dynamical properties analysis of a motorized spindle system

Abstract

The thermal expansion phenomenon of bearings happening on a motorized spindle has a great effect on its dynamical properties. Hence, there is a vital need to analyze the relationship between its cooling condition and dynamical behaviors for the system. A thermal–mechanical coupling model of a motorized spindle system is presented in this article, which consists of three coupling sub-models: bearing, thermal and spindle dynamical model. The bearings, taking the thermal expansion into count, provide the shaft with support stiffness which influences the spindle dynamical properties. And their power loss is one of the main heat sources of the system while the other one is from the motor. In the thermal model, the cooling condition and heat generation jointly determine the temperature rise and thermal expansion. Thus, all of the sub-models interact and the system becomes an integrated thermal–mechanical coupling model. The proposed model is investigated by a solution procedure and validated experimentally. And the effects of the rotational speed, cooling water flow rate and oil-air pressure on the spindle dynamical properties are provided by this mathematical model as well as the experiments. The good agreement of results from them indicates that this model is capable of predicting the dynamical properties of the motorized spindle system. Then some feasible methods to improve the dynamical behaviors of the system are obtained.