Optimized Radius of Roller Large End Face in Tapered Roller Bearings(Machine Elements, Design and Manufacturing)

A basic tapered roller bearing consists of a compliment of tapered rollers that are arranged between inner and outer rings having conical raceways. The inner and outer ring of a tapered roller bearing is commonly referred to as a cone and a cup respectively. Because tapered roller bearings can support both a relatively high radial load and a singledirectional axial load, they are widely used in drive systems in automobiles and railway cars, steel mill machines, and other industrial applications. The apex of the inner and outer ring raceways and the roller contact surfaces of a tapered roller bearing converge on the bearing centerline. The rollers develop pure rolling motion without sliding on the conical raceway surfaces. However, when a radial load acts on the bearing, an axial component force occurs on the rollers due to a disparity in angles between the inner and outer ring raceways. As a typical means for bearing this force, a cone flange is provided. As a result, the large end face of each roller is guided while being forced to the cone flange. Though each roller undergoes pure rolling motion on the raceway surface, there remains rolling-sliding contact between the roller Tapered roller bearings can support heavy combined radial and thrust loads, and are widely used for automobiles, railcars and industrial machines. The bearings have an inner ring rib into which the large ends of rollers are thrust, and the contacts are accompanied with rolling-sliding motions. The arge ends of rollers and the rib surfaces are spherical and conical in shape, respectively. The typical lubrication regime of the contact is elastohydrodynamic lubrication (EHL). However, some surface damage may occur if the oil film formation is insufficient due to low-rotational and/or heavy-load operations. The film thickness should be thick enough to prevent damage in a given operating condition. In this paper, an EHL numerical model is developed in consideration of both asperity contact and roller skewing. A parameter study shows that to form thicker oil films the optimum radius of the large end face of a roller is about 85% that of the rib face conical surface.