Research on two methods for improving the axial static and dynamic characteristics of hydrostatic lead screws

This paper researches two methods for improving the axial static and dynamic characteristics of hydrostatic lead screws, i.e. (a) using membrane restrictor instead of capillary restrictor and (b) utilizing the intentional periodic pitch errors in the nut to generate hydrodynamic effect of the lubricating film. The Reynolds' equation, which is applicable to the lubricating film in hydrostatic lead screws, is deduced based on the equivalent plane of the flank surface of threads. The perturbation technique and the finite difference method are used to obtain the static and dynamic characteristics. The JFO boundary condition is used for capturing the cavitation. The results show that the axial static and dynamic characteristics can gain a marked improvement by combining the two methods.