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本文应用Chiu的缺油理论,计算微型球轴承缺油的EHL膜厚和缺油开始的速度。为了说明理论的正确性,必须直接测出轴承中的平均膜厚。膜厚是用文献中所述的应变技术测量。测试结果和Hamrock-Dowson公式的理论预测值比较:在速度参数U小于10~(-10)时,两者有良好的一致性;但在速度参数较高时,由于缺油和进口剪切热效应,使膜厚比理论预测的小得多;然而缺油似乎是减小Hamrock-Dowson等温富油EHL理论值的主要原因。球轴承EHL实验揭示缺油程度随滚动速度和粘度而增加。滚动轴承中的缺油,是由于在前后两次接触间隔内补充到滚道中的油量不够充分。缺油后平坦区的膜厚决定于速度-粘度的乘积和缺油参数θ,后者包括油-气界面张力、压粘系数、球间距、接触形状和尺寸,以及滚道外边的膜厚。为了比较油和脂的润滑性能,对几种润滑剂在各种轴承速度下进行了膜厚的测量。本文主要目的在于:(a)实验测定油承中的膜厚;(b)确定缺油开始的速度;(c)确定膜厚减小程度;(d)分析影响缺油的因素和改进方法。
In this paper, Chiu’s theory of lack of oil was used to calculate the film thickness of EHL and the rate of lack of oil in the miniature ball bearings. In order to show the correctness of the theory, the average thickness of the bearing must be measured directly. Film thickness is measured using the strain technique described in the literature. The test results are compared with the theoretical predictions of Hamrock-Dowson formula: when the speed parameter U is less than 10 ~ (-10), the two have good consistency; but when the speed parameter is high, due to the lack of oil and the shear effect , Making the film thickness much smaller than predicted theoretically; however, lack of oil appears to be the primary reason for reducing the theoretical Hammerock-Dowson EHL value. Ball bearing EHL experiments revealed that the degree of lack of oil increased with rolling speed and viscosity. The lack of oil in the rolling bearing is due to the insufficient amount of oil replenished into the raceway between the two contact intervals. The film thickness of the flat area after a lack of oil is determined by the product of velocity-viscosity and the oil-deficient parameter θ, which includes the oil-air interfacial tension, the pressure viscous coefficient, the ball spacing, the contact shape and size, and the film thickness outside the raceway. To compare the lubricity of oils and greases, several lubricants were measured for film thickness at various bearing speeds. The main purpose of this paper is to: (a) experimentally determine the film thickness in the oil bearing; (b) to determine the rate at which the lack of oil begins; (c) to determine the extent of the reduction in film thickness; and (d) to analyze the factors that affect oil shortages and how to improve them.