추력을 받는 깊은 홈 볼 베어링의 피로 수명 예측을 통한 예압 설정

Abstract

A preload is commonly applied to high-speed rolling bearings to reduce vibration and prevent sliding between rolling elements and raceways. However, excessive preload can lead to abnormal heat generation, increased frictional torque, and reduced fatigue life. This study examines a high-speed rotating shaft supported by two deep groove ball bearings under thrust load and presents a method for determining the appropriate preload based on fatigue life prediction results. A simplified model is developed to estimate the axial loads acting on the bearings. In this model, the inner rings of the bearings are press-fitted onto the shaft, creating a rotating body with the shaft. The rotating body, balls, and outer rings move solely in the axial direction under the assumption that the multiple balls in each bearing behave as a single ball. All loads are treated as axial loads applied to the rotating body, resulting in a net sum of zero. The analysis reveals that the bearing loads are simple functions of only the thrust load and the preload amount in certain cases. In addition, fatigue life prediction results indicate that an optimal preload level exists that can enhance the fatigue life of one bearing while preventing other failure modes in the other bearing.