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Journal of Mechanical Science and Technology

, Volume 33, Issue 11, pp 5199–5207 | Cite as

Dynamic analysis of 5-DOFs aerostatic spindles considering tilting motion with varying stiffness and damping of thrust bearings

  • Jiasheng Li
  • Pinkuan LiuEmail author
Article
  • 4 Downloads

Abstract

Aerostatic bearings are of great importance for improving machining accuracy of a workpiece surface. The dynamics of air bearings and aerostatic spindle system in ultra-precision machine, which mainly causes mid-spatial waviness errors, has a great effect on surface topography. The dynamic coefficients of the thrust bearings were determined by adopting the perturbation method and finite difference method with MATLAB® software. In addition, the influences of the spindle speed and tilt angle conducted upon the dynamics of the thrust bearings were investigated in detail. The dynamic response of the spindle system, which is closely related to the performance of the thrust bearing and does not work only by the effect of the journal bearing, supported by pressured air film was obtained. The simulation analysis of spindle responses under cutting force and experiment results is well matched, and the analysis method proposed in this paper can be also applicable to other air bearing spindle systems.

Keywords

Aerostatic spindle Dynamic characteristics Dynamic model Thrust bearing Varying stiffness 

Nomenclature

Ω

Spindle speed (rad/s)

vz

Velocity of the gas around z axis

vβ

Velocity of the gas in the β direction

R

Journal radius

C

Bearing clearance (m)

d0

Restrictor inner diameter (m)

Dimensionless thickness of the gas film

m

Rotor mass (kg)

p

Gas film pressure (N/m2)

Dimensionless pressure

pa

Ambient pressure

ps

Gas supply pressure (N/m2)

R

Journal bearing radius (m)

Λ

Bearing number

γ

Whirl ratio

μ

Dynamic viscosity (Ns/m2)

τ

Dimensionless time

φx, φy

Tilt angle at steady state (rad)

ε0

Eccentricity ratio at the steady state

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Notes

Acknowledgments

This work is partially supported by the Science Challenge Project (Grant No. JCKY2016212A506-0105) and the National Natural Science Foundation of China (Grant No. 51135009).

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Copyright information

© KSME & Springer 2019

Authors and Affiliations

  1. 1.State Key Laboratory of Mechanical System and VibrationShanghai Jiao Tong UniversityShanghaiChina
  2. 2.School of Mechanical EngineeringShanghai Jiao Tong UniversityShanghaiChina

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