An Accuracy-Improved Torque Calculation Method for Ball Bearings under Fully Flooded Lubrication -Part 1: Viscous Rolling Resistance Formulas for Contact and Non-Contact Zones-

Accurate prediction of ball bearing torque is essential for reducing the torque in rotating machinery. Viscous rolling resistance, which dominates the ball bearing torque under fully flooded lubrication, has been estimated to use regression formulas derived from isothermal elastohydrodynamic lubrication (EHL) analysis. However, existing regression formulas calculate different values due to differences in integration domain and assumptions about contact position. This study proposes regression formulas for viscous rolling resistance accounts for both contact and non-contact zones. The formula of the non-contact zones is introduced the lengths from the Hertzian contact center to each raceway edge as parameters. Thereby, the proposed formulas enable accurate calculation across various Hertzian contact ellipse positions, sizes, and raceway widths. In addition, this formula demonstrates agreement with EHL analysis and can estimate the viscous rolling resistance across diverse integration domain compared to existing formulas.