| High-speed angular contact ball bearing is commonly used in the high-speed motor spindle as the main supporting element,its behavior is the key to the performance of the high-speed motor spindle.Friction heat generated between rolling elements,bearings rings and retainer lead to unstable operation and invalid of bearings,it also influences the performance of the high-speed motor spindle.The air-oil lubrication can effectively reduce bearing temperature rise and become its main lubrication method.It is necessary to study the influence of oil-air lubrication on the thermal characteristics of bearings.Based on the Elastohydrodynamic lubrication theory,bearing dynamics and thermo dynamics,the fluid domain and solid domain model of 7006 C angular contact ball bearing are established.The CFD methods and finite element methods are used to analyze the fluidsolid coupled thermal characteristics of the air-oil lubrication for bearings.The influence of lubrication parameters and operating conditions on air-oil lubrication characteristics and deformation characteristics of bearings is researched.The results show that1)The mach number of air-oil flow is more than 0.3 in the domain nearby inlet and outlet,if the numerical simulation of air-oil lubrication flow field of bearings is carried out without considering the compressibility of air,the analysis results of temperature rise on bearings will be high and inaccurate in comparison with the experimental results;the analysis results will approximate to the experimental results with considering the compressibility of air,both have the similar variation trends.2)The flow rate of air-oil lubrication in bearing chambers is high in the domain nearby inlet and outlet and low in the domain nearby balls and retainer,there is vortex in the domain among the balls;lubricating oil mainly distribute on the surface of inner ring,outer ring and balls,little distribute on the surface of retainer;the static pressure in bearing chambers will rise with the rising of the air supply pressure;the increase in the speed and the load will increases the bearing temperature rise,the increase in the supply pressure and the number of air-oil inlets will reduce the bearing temperature rise;using the symmetric distributed inlets will make the distribution of temperature field in bearing chamber be more uniform.3)The temperature field of solid domain in inner and outer ferrules of bearings affected by the temperature field of air-oil flow field,both have the similar regularity of distribution,the high temperature regions in bearing chamber mainly distributed in the domain nearby contact zone of balls and rollways,the low temperature regions in bearings chamber mainly distributed in the domain nearby inlet;portion of the heat generated by friction of bearing elements conducted along the normal direction of the rollway surface to the outward in bearing rings,and the temperature field of solid domain in bearing rings is radially distributed.4)The thermal deformation energy is high in the high-temperature domain of bearing rings and is low in the low-temperature domain of bearing rings;the thermal deformation energy and the thermal strain will increase with the rising of temperature in bearing chambers;increase the number of inlets will increase the flux of air,decrease the temperature rise of bearings,reduce the thermal deformation energy and thermal strain of bearing rings;if use the axisymmetric distribution inlets,the thermal deformation component of bearing rings will reduced in the direction perpendicular to symmetry axis and the total thermal deformation of bearing rings will reduced.The study provides an effective method to research the air-oil lubrication of bearings and some reference for the design of bearing parameters. |
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