Study On The Influence Mechanism Of Worn Surface Morphology Evolution Process On Slipper Pair Lubrication Performance

Axial piston pump is the core power component of hydraulic transmission system in aerospace,construction machinery and heavy equipment fields.The early wear of its key friction pairs is directly related to the reliability and service life of the whole machine,especially the weakest of them,the slipper pair,which is prone to wear failure under harsh working conditions,resulting in carrying ability failure of itself and even scrapping of the whole pump.Therefore,studying the variation law of the lubrication characteristics of the slipper pair during the worn surface evolution process is helpful to detect the early wear failure of slipper pair and accurately evaluate its lubrication performance degradation state is essential to adopt timely and effective predictive maintenance strategies to ensure the safe and stable operation of axial piston pumps.In this paper,the mixed thermal elastohydrodynamic lubrication characteristics of slipper pair during worn surface evolution process are studied by combining theoretical modeling,numerical simulation and experimental verification.The specific works are as follows:(1)The working principle,motion and force of the slipper pair are analyzed.Based on the hydrodynamic lubrication theory,the oil film thickness and oil film pressure equation of the slipper pair are described.Considering the fluid-solid coupling heat transfer characteristics of the slipper pair,the temperature control equation,heat conduction equation and surface deformation equation are established.Finally,the discrete and numerical solution methods of pressure control equation and temperature control equation are given.(2)Based on the fractal theory,the wear surface morphology of the slipper is established.The surface morphology is combined with the hydrodynamic lubrication model and the heat flow solid coupling model.The mixed lubrication model and the mixed thermal elastohydrodynamic lubrication model of the slipper pair are established successively.The effects of surface morphology and surface deformation on the oil film thickness field,pressure field and lubrication characteristic parameter of the slipper pair during wear degradation are discussed respectively.(3)The accelerated wear degradation state simulation test device of slipper pair is built.The principle and method of slipper pair working condition simulation,oil film thickness measurement and surface morphology acquisition are given.The change information of surface morphology,oil film thickness and leakage of slipper in different wear stages are recorded,which verified the accuracy of the theoretical model and the correctness of the analysis results.