The modification of the raceway profile in the double row slewing bearing

The slewing bearings are applied in heavy working machines and operated in extreme conditions. A characteristic feature of these bearings are a high load which determining a large deflection of a contact zone rolling element - raceway. This phenomenon combined with the effects of a bearing clearance causes a significant increase in a contact angle of the bearing. This in turn causes displacement of the contact zone to an undesirable position. In the construction of slewing bearing is applied of a large value of the osculation ratio. This leads to occur of large sizes of the contact zone identified in a radial cross-section. The sizes are comparable to values of the radius of the ball. The contact zone is type of quasi-linear. Effects of changes the position of the contact zone in the double-row ball slewing bearing has been presented in the paper. The raceway profile for such bearing consists of the arc section changing in the radial section. When the contact zone includes a change point of curvature of the raceway profile it comes to a concentration of a contact stress, and this is unfavourable for operation of the bearing. In order to eliminate this phenomenon to the profile introduced a transition curve. For this purpose was selected a clothoid. The curve ensures a gradual change of curvature from the arc section of the profile to the zero curvature of the straight profile section. The raceway profile becomes the smooth curve of the second rank. In the article are presented a numerical model of the contact zone for the double-row ball slewing bearing and the distributions of a pressure in the contact zone for the ordinary and modified raceway profiles. The calculation results have been presented as graphs of the distributions of the pressure along the contact zone. It has been shown that the introduction modification of the raceway profile eliminates the concentration of the pressure along the contact zone profile. The results obtained can be used during design of the raceway profiles of the double-row ball slewing bearing.