Research On Lubrication And Friction Of Spherical Plain Bearing Lubricated With Non-Newtonian Fluid And Service Life Prediction

Spherical plain bearing is a kind, of journal bearing with a spherical frictional surface. It is widely used in the field of aerospace,construction machines and military industry as well as transport machinery. The foundational research on its hydrodynamic lubrication, friction and wear properties and wear life prediction has not only theoretical significance, but also practical sense for improving the quality of design and manufacturing, enhancing the safety, stability and reliability of mechanical system. For the purpose of enhancing the frictional performance and lubricating properties of spherical plain bearings operated under grease lubrication condition, the research work on the numerical analysis of bearing lubrication performance,designing of surface texturing on the frictional surface and the experiment of its effects on friction-reducing, frictional properties prediction of textured contact surfaces as well as wear life prediction of bearing were carried out. All these research offer the theoretical basis for the designing, manufacturing and service of spherical plain bearing.First of all, based on hydrodynamic lubrication theory, a fluid dynamics model was established in the spherical coordinate. In this model, the rotational and oscillating traverse motion of the inner ring, the journal misalignment were considered, meanwhile the Non-Newtonian behavior of grease was also took into account. And as a result, a general Reynolds equation was deduced.. It provides a theoretical basis for numerical analysis of spherical bearings lubricated with Non-Newtonian fluid.Secondly, in order to analyse the effects of the friction system parameters on the lubrication performance, a numerical simulation work which use finite difference method was carried out to solve the lubrication problem of the bearing lubricated with grease of which the rheological behavior is governed by Ostwald model. Meanwhile,a CFD (Computational Fluid Dynamics) model was established to analyse the influence of cavitation effect on bearing lubrication performance.Thirdly, different texture forms were designed and fabricated with laser beam on the inner contact surface of the bearing. All samples were measured to obtain 3D topography by using a non-contact 3D surface profile. The textured surface topography was characterized by IS025178-2 surface topography parameters. The relation between texture parameters and characterization parameters was explored and as a result,4 characterization parameters were selected as the parameters to predict the bearing frictional performance. These 4 characterization parameters: Ssk, Sku,Sdv and Vw are sensitive to texture parameters. Tribological experimental was carried out to study the influence of operation parameters, surface texture parameters and 3D surface characterization parameters on the frictional properties of bearing with texture on its contact surface. The results showed that it is feasible and effective to predict the frictional performance by using the forgoing 4 parameters. Also, a simplified one-dimensional Reynolds equation was deduced and solved by numerical method to study the effects of surface texture on the frictional properties.Finally, the wear test of bearing steel (GCr15) under grease lubricated,reciprocating conditions was carried out on a friction and wear test machine. The wear mass loss of bearing steel was gained by using weighing method, and obtained the relationship between wear rate and surface pressure by using fitting method. And then,a computing model of spherical plain bearing was developed by using joint wear calculation method and as a result, a simple and practical wear life formula was deduced.The research analysed the influences on bearing lubrication properties, indicated that surface texture has great significance for enhancing bearing frictional performance. Also, this research proved that it is effective and feasible to apply surface texture in spherical plain bearings. The results may supply theoretical support in basic research of spherical plain bearing, and also provide guiding principle for its industrial application.