| High-speed angular contact ball bearings have the effect of bearing both axial and radial loads.Therefore,they are widely used in the support unit of high-speed electric spindles,Oil-air lubrication is the main lubrication method of high-speed angular contact ball bearings.It is great significant to study and improve the distribution of oil-air two-phase flow in the bearing cavity under high-speed working conditions.Based on elastohydrodynamic lubrication theory,fluid dynamics and bearing heat generation theory,this paper takes SKF7210 C high-speed angular contact ball bearing as an example,a high-precision numerical model of the bearing cavity was establish,the influence of oil-air inlet and outlet position on oil,temperature rise and pressure distribution in the cavity was systematically.This study will provide a theoretical basis for optimizing the structure of oil-air inlet and outlet.The main conclusions of this paper are:(1)The oil phase volume fraction and temperature rise in the bearing cavity are not evenly distributed in the circumferential direction.The lubricating oil has the highest oil phase volume fraction near the oil-air inlet.With the increases of the distance from the inlet to outlet,the oil phase volume fraction gradually decreases.The gradient of the oil phase volume fraction in the direction of the bearing is slower,and the gradient of the oil phase volume fraction in the opposite direction of rotation is faster.The temperature rise in the bearing cavity is inversely proportional the oil phase volume fraction.Temperature rise is low at high volume fraction of oil phase,the reverse is also true.(2)Angular contact ball bearings will produce an air curtain effect in the bearing cavity under high-speed conditions,and the air curtain effect will be intensify with the increase of the speed,and when the speed increases,the cyclone center will be decreased,making it more difficult for the lubricating oil to enter the lubrication contact area.which causes insufficient lubrication and other phenomena.The oil-air inlet structure is an important factor that affects the formation of cyclones in the bearing cavity.By comparing and analyzing the air curtain effect,oil phase volume fraction,temperature rise and pressure in the bearing cavity under the five oil-air inlet structures,Among them,the D-type entrance structure is the best.Simultaneously,It can be obtained the inlet structure how to slows down the air curtain effect and avoid the collision caused by the high pressure of the oil-air inlet and the cyclone,so thatthe lubricating oil can reach the contact area of the inner ring raceway and the ball,thereby improving the use efficiency of the lubricating oil and improving the working condition of the bearing.(3)The angle between the oil-air inlet and outlet in the circumferential direction has great effect on the distribution of the lubricating oil and temperature rise in the bearing cavity.When the angle between the outlet and the inlet is increased 180 ° to 240 °,the oil phase volume fraction in the bearing cavity gradually increases and the temperature rise decreases.When the angle between the outlet and the inlet is 240 °,the oil phase volume fraction in the bearing cavity reaches the highest and the temperature rise is the lowest.When the angle between the outlet and the inlet is increased 240 ° to 270 °,the oil phase volume fraction in the bearing cavity gradually decreases and the temperature rise increases.The above analysis can get the best angle between the outlet and the inlet is at 240 °,thus providing a new direction of thinking for improving bearing lubrication. |
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