Multibody dynamic model of a double nut preloaded ball screw mechanism with lubrication

Ball screws have been investigated by several researchers from a theoretical point of view because the intrinsic complexity of experimental investigation of these mechanisms. Most of the models developed so far have been developed in quasi-static conditions ignoring inertia terms and time variability of operating conditions. A detailed multibody dynamic model of a double nut preloaded ball screw is presented in this paper, taking into account the full dynamic of each subcomponent as well as the mutual interactions. A 3D contact model is introduced, considering Hertzian normal contact and a simplified friction model based on grease lubrication. This model takes into account the time variability of the operating conditions and it is suitable to be used for prognostic and model-based design approaches. The results of dynamic simulations in presence of backlash are presented to highlight the model s capabilities.