Research on load carrying capacity and stability of air bearing spindles restricted by unevenly-distributed orifices with different diameters
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.
gas journal spindlefinite difference method(FDM)load carrying capacitystabilityorifice with variable diameter