不同工况下表面粗糙度对水润滑轴承启动性能的影响

Effects of Surface Roughness on Transient Performance of Water Lubricated Bearings During Start-Up under Different Working Conditions

关键词:  水润滑轴承  启动过程  表面粗糙度  主轴运动  润滑性能  轴承温度

Key words:  Water lubricated bearing  Start-up  Surface roughness  Shaft motion  Lubrication performance  Bearing temperature

摘要:

为研究水润滑轴承的瞬态启动过程，联立瞬态压力场、温度场控制方程及主轴运动方程，构建水润滑轴承瞬态启动模型，从主轴运动、润滑性能及轴承温度等方面，分析不同表面粗糙峰高度（1μm，2μm，4μm）下的水润滑轴承启动性能参数变化规律。结果表明：在轴承启动初期主轴发生强烈的瞬间振动，导致膜厚、压力、承载力、摩擦系数等主要参数发生瞬间急剧变化，且主轴振动随表面粗糙峰高度的增大而更加强烈；降低粗糙峰高度可促进水膜承载，使固体接触压力、接触承载力和摩擦系数降低，但最小膜厚也会随之减小；轴承运行中存在某一个转速使得轴承温度达到最高值，而随着粗糙峰高度的增加，该最高温度值及其对应的主轴转速均随之增大，这会加剧轴承高温失效风险。

Abstract:

In order to study the transient start-up process of water lubricated bearings，the starting model of water-lubricated bearing is established by simultaneous transient pressure field， temperature field governing equation and shaft motion equation， the variation of starting performance parameters of water-lubricated bearings with different surface roughness peak heights （1μm， 2μm， 4μm） is analyzed from the shaft motion， lubrication performance and bearing temperature. The results show that： A drastic instantaneous vibration occurs on the shaft at the initial stage of start-up， which cause the sudden and sharp changes in the parameters such as film thickness， pressure， bearing capacity and friction coefficient， and the vibration becomes more intense with the increase of surface roughness peak heights. Reducing the height of the surface roughness can promote the water film load， and reduce the asperity contact pressure， contact capacity and friction coefficient， but the minimum film thickness will also decrease accordingly. A certain shaft speed will make the bearing temperature reach maximum， and the maximum temperature value and the shaft speed increase with the surface roughness height increases， which will increase the risk of bearing high temperature failure.