Boundary-Adapted Numerical Modeling of Flow in a Hydrostatic Leadscrew

Abstract

A new method is presented to model and predict the flow fields of the hydrostatic leadscrews with greater accuracy. It is different from those available methods, in which various bearings are assumed to be equivalent to the screw-nut pair within a pitch by various means. In this new method, a helical coordinate system adapting to the boundaries of the flow fields is constructed, which makes the screw-nut meshing clearance calculated more accurate. Based on the finite difference method (FDM), the meshing clearance is discretized into a number of flow fields, which are created by numerous couples of parallel-plate elements moving relatively along the helicoid. The numerical model is solved in MATLAB, and the analyses about the pressure fields demonstrate its favorable performances in reflecting the actual flow fields. Furthermore, the simulation results are compared with the experimental values, confirming the feasibility of the proposed method.

Friction Parameters Dynamic Change and Compensation for a Novel Dual-Drive Micro-Feeding System

“…The DDMS has two structural forms: hydraulic screw drive and ball screw drive. For the DDMS based on the hydrostatic screw nut pair, Su proposed a numerical model for the flow boundary for the hydrostatic screw [7], and Liu investigated the boundary slip characteristics within the hydrostatic screw under both DDMS and CFDS driving methods [8]. For the DDMS based on the ball screw nut pair, Yu performed a velocity spectrum analysis [9], Du proposed a full component friction identification model [10], and Wang investigated the effect of torque harmonics on the speed fluctuations of linear feed systems at low speeds; compared with CFDS, DDMS avoids the system resonance caused by torque harmonics at certain speed points [11].…”