Performance Research on Bi-directional Tilting Pad Thrust Bearing Considering the Verticality Error of Thrust Plate

In order to improve the axial stiffness and its controllability of the CNC machine tool spindle system, a bi-directional tilting pad thrust bearing is used instead of the hydrostatic thrust bearing to bear the axial load. Due to the processing and installing, there must be a certain verticality error between the thrust plate and rotor axis. The lubrication model of the thrust bearing considering the verticality error is established in this paper. The Reynolds equation is solved by FDM (finite difference method), and the key performance data of the bi-directional tilting pad thrust bearing under rated conditions are obtained, including eccentricity, minimum film thickness, maximum temperature rise and axial stiffness, etc. The variation of performance parameters such as film thickness, temperature rise and stiffness of thrust bearing with different working conditions are mainly studied. The maximum allowable verticality errors in the whole working condition range of load and speed are given. According to the requirements of film thickness and temperature rise, the thrust bearing clearance is optimized based on the comprehensive consideration of lubrication performance and dynamic performance, and the allowable ranges of clearance under different verticality errors is analyzed. This research provides theoretical guidance for the design and manufacture of tilting pad thrust bearings used for the CNC machine tool spindle system.