Dynamic Coefficients Identification of Water-Lubricated Hybrid Bearings Used in High-Speed Spindles with Different Excitation Methods

Lin Wang,Hua Xu,Xianzhi Xiong

doi:10.1155/2017/2597910

Abstract

Rotor stability and rotation accuracy, which are highly dependent on the dynamic coefficients of supporting hybrid bearings, are two important issues of high-speed water-lubricated spindles. To improve the spindles’ performance, the dynamic coefficients of high-speed water-lubricated hybrid bearings were experimentally identified by the noncontact harmonic excitation method and the additional unbalance excitation method, respectively. Comparisons between experimental results and theoretical predictions were made. The experimental technique and the identification model were validated to be effective. Besides, the influence of supply pressure and rotating speed on dynamic coefficients was also presented. As for different operating conditions, valuable guides were provided to investigate the dynamic performance of high-speed and ultra-high-speed spindles.

Highlights

For the advantages of low temperature rise, high rotating speed, and long life-span, water-lubricated hybrid bearings have been used in high-speed machine tools
The direct stiffness coefficients increase with water supply pressure and spindle rotating speed owing to the hydrostatic effect and the hydrodynamic effect, respectively
This study identifies the dynamic coefficients of high-speed water-lubricated hybrid bearings with circumferential grooves and stepped recesses

Summary

Introduction

For the advantages of low temperature rise, high rotating speed, and long life-span, water-lubricated hybrid bearings have been used in high-speed machine tools. Dynamic coefficients of water-lubricated hybrid bearings have been experimentally investigated by the inverse method [11, 12], in which the exciting force is applied on the moving bearing housing. The noncontact harmonic excitation method and the additional unbalance excitation method are firstly used to identify the dynamic coefficients of high-speed water-lubricated hybrid bearings with circumferential grooves and stepped recesses. Sudheer Kumar Reddy et al [22] investigated the stiffness and damping coefficients of tilting pad journal bearings with small L/D ratios using the noncontact excitation method. The dynamic coefficients of water-lubricated hybrid bearings are identified by the noncontact harmonic excitation method and the additional unbalance excitation method, respectively. The influence of operating parameters, such as water supply pressure and spindle rotating speed, on dynamic coefficients is experimentally investigated

Test Rig and Identification Model

Results and Discussion

Conclusions