Dynamic analysis of water-lubricated motorized spindle considering tilting effect of thrust bearing

The dynamic modeling for the rotor with large diameter thrust bearings is one of the key issues in the design and operation of water-lubricated motorized spindle. In the machining process, the spindle not only translates along the x, y, z directions, but also tilts about the x and y axes under the cutting forces. As a result, the tilting effect of the thrust bearing on the dynamic performances of the motorized spindle should be considered. A five degree-of-freedom dynamic model for the spindle is established based on the Newton’s Laws and the principle of Angular Momentum. The translational and tilting dynamic coefficients for both the journal and thrust water-lubricated bearings were obtained by using Reynolds equation. The computed results show that the tilting effect of the thrust bearing on the dynamic performance of the motorized spindle should be considered when a large diameter thrust bearing is employed.