An Investigation on Dynamic Performance of Multi-point Contact Ball Bearings with Integrated Rings

Multi-point contact ball bearings are widely used in many fields such as aircraft development, high-speed rail, new energy and others because of their unique multi-race structure. However, due to excessive contact angle and multi-point contact status, the bearings are prone to thermal failure at high speeds, thus limiting the further expansion of their applications. To this end, the contact feature among the ball and raceways is investigated, a number of the relative positional relationships and velocities are further defined. Based on the theory of Hertzian and elastohydrodynamic lubrication, the govern equations of lubricant contact of the ball is established. Considering the dynamic effect of the cage, a common dynamic model of multi-point contact ball bearing is further established. Its predicted values are in good agreement with the experimental test values. On this basis, the spinning motion of each raceway under typical operating conditions is investigated. Some interesting results can be founded as follows: when the bearing is operated under purely axial load, there may be three contact points on the ball and a large spinning motion on one of the raceways. With the heavier axial load exerted on the bearing, this spinning motion would disappear as the ball moves out of contact with the raceway. Once the bearing is subjected to radial load, two contact points, three contact points and four contact points may occur sequentially for each revolution cycle of the ball. A maximum spinning on one raceway is generated when the ball is in the four-contact status. Crucially, the smaller initial contact angle helps to suppress the spin component on each raceway of the bearing at high speeds. This research provides theoretical guidance for the development of high-speed multi-point contact ball bearings.