非均匀分布变节流孔直径静压气浮主轴承载能力与稳定性研究

Research on load carrying capacity and stability of air bearing spindles restricted by unevenly-distributed orifices with different diameters

目的:研究节流孔分布和直径系数对主轴承载能力和稳定性的影响。方法:提出了非均匀分布变节流孔直径新型静压气浮主轴结构,采用有限差分结合线性小扰动法求解非稳态Reynolds方程计算主轴性能。结果:节流孔分布、节流孔直径系数、偏心率、供气压力和平均气膜厚度对主轴承载能力和稳定性有显著影响;偏心率为0.15、供气压力为0.6 MPa时,新型气浮主轴承载能力提高25%,节流孔直径系数为0.90~0.95时主轴承载能力最大。结论:偏心率越大,节流孔分布对主轴承载能力的影响越显著;相对于传统主轴,节流孔直径系数对新型主轴承载能力影响较小;气浮主轴承载能力随供气压力和偏心率增加而增大,随平均气膜厚度增大而减小;偏心率越小,节流孔非均匀分布提高主轴稳定性越显著,变节流孔直径有利于提高主轴临界涡动比,降低临界惯性力,增强主轴稳定性;增大平均气膜厚度有利于提高主轴稳定性;增加供气压力导致主轴临界惯性力增大,稳定性降低。

Aims:This paper aims to study the influence of throttle hole distribution and diameter coefficient on the bearing capacity and stability of the spindle.Methods:A new type of static pressure air bearing spindle structure with non-uniform distribution variable throttle hole diameters was proposed;and the finite difference combined with the linear small disturbance method was used to solve the non-stationary Reynolds equation and calculate the spindle performance.Results:The distribution of throttle holes,throttle hole diameter coefficient,eccentricity,gas supply pressure,and average gas film thickness had a significant impact on the bearing capacity and stability of the spindle.When the eccentricity was 0.15 and the gas supply pressure was 0.6 MPa,the bearing capacity of the new air bearing spindle increased by 25%.The maximum bearing capacity of the spindle was achieved when the diameter coefficient of the throttle hole was between 0.90 and 0.95.Conclusions:The greater the eccentricity is the more significant the impact of orifice distribution on bearing capacity is.Compared to traditional spindles,the diameter coefficient of the throttle hole has a smaller impact on the load-bearing capacity of the new spindle.The bearing capacity of the air bearing spindle increases with the increase of gas supply pressure and eccentricity,and decreases with the increase of average gas film thickness.The smaller the eccentricity is,the more significant the improvement of spindle stability is due to the non-uniform distribution of throttle holes.Changing the diameter of throttle holes is beneficial for increasing the critical vortex ratio of the spindle,reducing the critical inertial force,and enhancing spindle stability.Increasing the average gas film thickness is beneficial for improving the stability of the spindle.Increasing the gas supply pressure leads to an increase in the critical inertia force of the spindle and a decrease in stability.