| Oil-film bearing has long been known as the heart of rolling mill. Compared with rolling bearing, oil-film bearing possesses advantages like large carrying capacity, long lifespan, wide speed range, strong shock resistance ability, etc. With the requirements of modern society for rolling mill, such as efficiency, large-scale, heavy load and economics, higher new requirements are also posed to lubricating property of oil-film bearing. Roller and bearing should be separated with each other by lubricant media under ideal condition, yet during practical operation, the increase of rolling force and oil-film temperature will lead to contact friction and wear between roller and bearing, even bearing failure. Therefore, in this study, ferrofluid was introduced to replace traditional lubricating oil. The applied magnetic field will increase viscosity of ferrofluid, ensure the integrity and stability of oil film, and develop the load capacity of bearing. The friction and wear between roller and bearing will be prevented, bearing lifespan and roll element quality can be improved.In this paper, based on fluid lubrication theory, electromagnetic theory and ferrofluid hydrodynamics, the mathematical model of oil-film bearing lubricated with ferrofluid was improved. And the mathematical model of ferrofluid lubrication was nondimensionalized and dispersed, after which the corresponding program of ferrofluid-lubricated oil-film bearing mathematical model was developed with Fortran language based on Microsoft Visual Studio. Numerical solution of ferrofluid-lubricated oil-film bearing model was obtained. And lubricating property of ferrofluid-lubricated oil-film bearing under magnetic field, flow field, temperature field was quantified. The main research contents are as follows:Firstly, the mathematical model of oil-film bearing lubricated with ferrofluid was established, including viscosity equation, Reynolds equation, energy equation and equations on lubrication parameters which are connected with oil-film temperature, pressure and external magnetic field strength.Secondly, the mathematical model of ferrofluid lubrication was nondimensionalized and dispersed with finite difference method. Magnetic field intensity distribution within bearing twined with solenoid, the relation among viscosity of traditional lubricating oil and ferrofluid, oil-film temperature and external magnetic field intensity was studied with experiments.Finally, in accordance with the mathematical model of oil-film bearing lubricated with ferrofluid, lubricating property of oil-film bearing lubricated with traditional lubricating oil and ferrofluid under and not under magnetic field was solved with Fortran programming. Dimensionless oil-film pressure, oil-film temperature and oil-film thickness distribution under different conditions was obtained. |
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