Service Life of Universally Loaded Deep Groove Ball Bearing Depending on Internal Clearance

Abstract

The service life of a rolling bearing is calculated using a standardized formula, based on the bearing’s dynamic load rate, equivalent load, and the appropriate exponent, depending on the rolling elements’ shape. Deep groove ball (DGB) bearings are supplied to the market with radial internal clearance. Clearance ranges are classified into several size groups, with values depending on the bearing bore diameter. Radial clearance causes the presence of axial clearance. DGB bearing is a bearing with initial radial contact between balls and raceways (zero contact angle). This type of bearing can be loaded with pure radial load or universally loaded with combined radial and axial load. When a radial bearing is loaded only with a radial load or a combined load with a negligibly small axial component, the contact angle retains the zero value. When the axial component of the load is significantly large, there is an axial relative displacement of the rings for the value of the axial clearance. Then the radial bearing becomes a bearing with angular contact. In the standard calculation method, the expression of the service life does not explicitly take into account the internal clearance. However, the influence of the clearance is calculated indirectly, through the corresponding values of the equivalent dynamic load’s parameters. These parameters depend on the contact angle, and the contact angle depends on the internal clearance. Theoretical quantitative analysis of the internal clearance influence on the service life of a universally loaded DGB bearing is presented in this paper.