And Multi-field Coupling Properties Of Lubricating Oil Film Bearing A Magnetic Fluid-solid Mechanism

Oil-film bearing, as the supporting component of steel rolling machinery, has a uniqueadvantage and plays an important role in rolling production when comparing with rollingbearing. There is no frictional wear when bearing is under ideal lubrication, but it’s difficult toguarantee in the actual operation. The material of oil-film bearing in the inner surface isBabbitt metal and the operating temperature reaches30%of its fusion point. If bearingoperates under long-term conditions, creep would occur. At the same time, temperature risehas a negative effect on the viscosity of lubricating oil, which may affect the service life ofrolling mill and the quality of steel straightly. For this reasons, ferrofluid lubrication isintroduced. Ferrofluid can improve lubrication oil viscosity and load-carrying capacity ofbearing to protect bearing from failure by lubrication problems and improper loading. It’sconductive to reduce the number of oil-film bearing damage accidents and prolong service lifeof bearing.This thesis is based on the National Natural Science Fund “Research onMagnetic-fluid-solid Coupling Lubrication Mechanism and Interface Mechanic Behaviors ofLow-speed and Heavy-load Oil-film”(51205269), taking ferrofluid as lubrication medium,lubricating oil film as research object and oil-film bearing of rolling mill as application objectto explore the lubrication mechanism and property of ferrofluid-solid multi-field coupling ofoil-film bearing. According to fluid dynamics of ferrofluid and thermal elastohydrodynamiclubrication (TEL) of oil-film bearing, the mathematic model of ferrofluid lubricating oil-filmbearing is deduced. The plan of applied magnetic field is designed and the distribution ismeasured. The equation of ferrofluid viscosity is deduced and the influence of each factor isverified by experiments. Numerical modeling of ferrofluid-solid multi-field coupling iscarried out through finite element software. The main contents of this thesis are statedbriefly as follows:1. The mathematic model of ferrofluid lubricating oil-film bearing is established andnondimensionalized, numerical calculation method and flow chart are confirmed. Theinfluence of each design parameter is analyzed, the quantity of lubricating oil, force of friction,angle of displacement and distributions of oil-film velocity. The analysis of the effects oflubricating oil viscosity on oil-film characteristics is also conducted.2. The applied magnetic field of ferrofluid lubricating oil-film bearing is designed, and the distribution of inner magnetic field is obtained by theoretical calculation and tested byexperiment. The result shows that the data is close enough to provide magnetic field thatmeets requirement. Meanwhile, the equation of ferrofluid viscosity influenced by oil-filmtemperature, oil-film pressure and magnetic field intensity is deduced and checked, whichsupplies theoretical and experimental basis to the calculation of viscosity in lubricationmathematic model.3. Simulation of ferrofluid-solid multi-field coupling is conducted with Workbench.Oil-film pressure and temperature are figured out through the calculation of oil film with CFX.By establishing multi-field coupling connection, static analysis and temperature analysis areworked out respectively by Static Structure and Steady-State Thermal blocks. Distributions ofoil film temperature and pressure and other oil-film characteristics under different lubricatingand working conditions are achieved as well as the stress-strain and temperature distributionof structure.