Study On The Technology Of Piston Ring's Surface Laser Micro-texturing Based On Hydrodynamic Lubrication Theory

The tribopairs of piston ring-cylinder liner are one of the most important tribopairs in an internal combustion.With the development of engine aiming at high-speed and heavy-load,how to make the piston ring-cylinder liner system maintain a good lubrication condition has great importance in terms of reducing the friction and wear,prolonging the engine's longevity,improving economy/power/durability.In recent years, laser surface micro-texturing(LST),a technology to improve friction performance,has won extensive attention because of it's unique advantage such as easy to control,environment-friendly,stable processing quality.In order to improve the friction conditions of piston ring-cylinder liner,we apply the LST to piston ring surface modifying,which has important theoretic value and practical significance.Based on hydrodynamic lubrication theory,the content carries out numerical analysis on the lubrication performance of piston ring which surface has regular micropores structure and simulation experimental study. Firstly,take four pores in the axis direction of LST piston ring as the study object,establish a hydrodynamic lubrication mathematical model with regular paraboloid structure micropores on the surface of piston ring,along with Reynolds cavitation boundary condition,by way of modified multi-grid method and Matlab language,figure out the discrete mathematical model.Take the dimensionless average pressure of the fluid film as the criterion to estimate the LST piston ring's hydrodynamic lubrication performance,and mainly analyze the micropores' area density, depth and radius on piston ring's lubrication characteristics,then finally gain the optimized parameters of micropores.Secondly,adopt the technology of LST and use the "single pulse at the same point,interval more times" processing technics,an experimental study on quenching 45 steel sample is carried out and determining the rational laser micro-texturing technological parameters.Finally,carry out the friction and wear test on LST samples with the help of an experimental device which named UMT-2.The results show that the samples after laser micro-texturing can improve lubrication performance obviously,and the experimental results has well with the theoretical results.The achievements of this study has greatly important reference at the aspects of expanding LST applied in the other tribopairs of engines.