Influence Of Thermal Effect And Surface Waviness On Lubrication Characteristics For Journal Sliding Bearing

The surface roughness,surface waviness,surface damage and other appearance errors exist in the main shaft and bearing bush of sliding bearing.Among them,the surface waviness is the geometric error between the micro and macro,which is caused by the forced vibration of the machining system in the process of machining,the quality imbalance in the process of rotation and the irregular feeding of the cutting tools,and has strong periodicity.On the other hand,the surface waviness and thermal effect can affect the bearing performance at the same time,so it is necessary to consider the influence of the circumferential surface waviness and temperature viscosity relationship at the same time.Based on the perturbation theory,the disturbance Reynolds equation,the energy equation and the temperature viscosity relationship are established.The finite difference method and the finite element method are used to solve the dynamic and static pressure bearing discretely,and the static and dynamic characteristic parameters of the oil film are obtained.The low amplitude circumferential pressure bearing is analyzed The influence of the surface waviness on the lubrication performance of the bearing and the variation of the additional disturbance pressure with the wavelength.On the basis of theoretical calculation,the friction coefficient of oil film and other parameters under the influence of surface waviness of various wavelengths are measured through experiments,and the temperature distribution of hydrodynamic bearing with different materials is explored.The results show that the circumferential surface waviness will form a series of local convergence gap and local divergence gap between the bearing shell and the journal,and the size and position of the gap in the circumferential distribution will change with the wavelength,and these gaps will cause additional pressure fluctuation and lead to the phase shift of the pressure peak.For the dynamic pressure bearing,the flow rate,deflection angle,dimensionless friction and other parameters have negative correlation with the phase-shifting law of pressure distribution.For the unstable speed,when the eccentricity is small,the unstable speed of smooth surface is significantly higher than that after taking into account the surface waviness,and has a positive correlation with the phase of pressure peak.When the eccentricity is large,the unstable speed and sum of different wavelengths The phase of pressure peak shows negative correlation.For deep and shallow cavity hydrodynamic bearing,the bearing capacity is related to the pressure peak value,and the influence weight of the pressure peak phase decreases,but the dimensionless friction,end discharge and stiffness are still affected by the pressure peak phase shift,while the instability speed is proportional to the pressure distribution peak valueThe experimental results show that the axial temperature distribution of the hydrodynamic bearing,the temperature at the end surface is higher than that at the center,which verifies the simulation results of the temperature field of the hydrodynamic bearing;for the influence of the surface waviness,it verifies the deviation of the friction coefficient of the bearing under different wavelengths,the friction coefficient decreases with the increase of the wavelength,which is in good agreement with the simulation results.