Development of Dynamic Analysis Technology for High-Speed Tapered Roller Bearings

Hideaki Kikuchi

Summary

In recent years, there has been an increasing demand for space saving and weight reduction in the environment where rolling bearings are used. In machine tool spindles in particular, where high rigidity is required, multi-rows of ball bearings or cylindrical roller bearings are commonly used, but tapered roller bearings are advantageous because they can provide sufficient rigidity with fewer bearing rows. However, under high-speed operation with lubrication conditions where the amount of oil supplied, such as oil-air or grease, is limited, damage such as seizure may occur due to insufficient oil on the large rib face (i.e., starvation). Factors affecting starvation include rolling speed, lubricant viscosity, contact width, film thickness, and surface tension. In addition, it has been pointed out that on the large rib face, changes in clearance distribution caused by changes in roller orientation (skew) affect oil film formation. Therefore, it is necessary to comprehensively consider these factors when evaluating the high-speed performance of tapered roller bearings. In this study, an elastohydrodynamic lubrication (EHL) analysis was conducted considering starvation of the large rib face to formulate the lubrication phenomenon. The obtained equations were incorporated into the bearing dynamic analysis program that includes thermal analysis, and the validity of the analysis results was verified through bearing tests.