Analysis on Elastohydrodynamic Lubrication in Grease-lubricated Ball Bearings Considering Film Thickness Correction

Analysis on Elastohydrodynamic Lubrication in Grease-lubricated Ball Bearings Considering Film Thickness Correction

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To study the lubrication characteristics of grease-lubricated rolling ball bearings, such as film thickness and pressure variations in elastohydrodynamic lubrication with elliptical point contact, a numerical analysis Camcorder model of elastohydrodynamic grease lubrication is firstly constructed.This model is based on the Herschel-Bulkley rheological model of lubricating grease and includes the constitutive equation for grease, Reynolds equation, film thickness equation, viscosity-pressure equation, density-pressure equation, and load balance equation.Then, a modified film thickness formula proposed in this study, based on the Hamrock-Dowson approach, is applied to calculate and adjust the film thickness within the model.Finally, the model is solved numerically using a direct iteration method to analyze the effects of different rheological indices, ellipticity, entrainment speeds, and loads on the film thickness and pressure of the Pentair MagicBowl Parts grease.The results are also compared with the film thickness and pressure trends of Newtonian fluids under the same conditions of ellipticity, entrainment speed, and load.

The results show that the model solutions, which account for film thickness modifications, more closely match the experimental data.Additionally, as the entrainment speed and rheological index decrease, the grease film thickness decreases, and the grease film pressure in the contact area approaches the maximum Hertz pressure.As the ellipticity increases, the peak grease film pressure significantly decreases, and the film thickness slightly increases.Compared to Newtonian fluids, the impact of load and entrainment speed on the lubrication film thickness and pressure distribution in the grease lubrication is smaller.