A Non-Ideal Geometry Based Prediction Approach of Fitting Performance and Leakage Characteristic of Precision Couplings

Since current studies on the leakage flow of precision couplings are based on the ideal smooth surface, neglecting the influence of geometric structures of machined surfaces, here we proposed a non-ideal geometry-based approach in this paper to perform a more accurate prediction on the fitting performance and the leakage characteristic of precision couplings. Firstly, a non-ideal geometric surface model of precision couplings is established by fractal function that characterizes both the dimensional discrepancy and the form error of key fitting surfaces, and theoretical calculation formulas based on the non-ideal geometric model are proposed afterward to predict the fitting performance and the leakage flow rate of precision couplings. Then, the influence of various factors on the leakage flow is also analyzed by the CFD approach. Simulation results and experimental results are compared to the theoretical calculation results, so the prediction approach proposed in this paper is verified to be feasible and accurate. Finally, the proposed approach is applied to the assembly analysis of spool valve of electro-hydraulic servo valve.