Abstract: A pure rolling cage-free ball bearing design method is proposed from the axial and radial perspectives of the bearing to solve the problems of high-speed bearing slippage and cage failure. Its correctness and effectiveness are verified by example. This method is first based on tribological theory to derive the pristine rolling boundary condition of the bearing and introduces the concept of axial friction angle. The concept of axial friction angle is introduced. The radial and axial displacement of the rolling body are limited by the radial clearance and raceway bus, respectively. The raceway's complex form of rolling body motion is simplified to a single pure rolling, and the cage is eliminated while the rolling body capacity is increased. Thus, the radial clearance is mapped to the design of bearing inner and outer ring raceway bushes, and the calculation model and design principle of raceway bushes of cageless bearings based on axial friction angle are established. Finally, based on the above method, a novel cageless bearing structure is proposed with a logarithmic helix design for inner and outer ring raceways. Its dynamic performance is evaluated by bearing characteristic test. The results show that the novel bearing can achieve nearly pure rolling, replacing sliding friction with rolling friction, significantly reducing the frictional heat problem of the bearing, and significantly increasing the permissible maximum speed of the bearing. Under 3 kN axial load, the ultimate speed of the bearing is 32 000 r/min, and the D_mN value can reach 2.8× 10⁶ mm·r/min. At a speed of 20 900 r/min, the bearing can withstand an axial load of 20 kN and has a high load-carrying capacity. It can meet the application requirements for high-load and high-speed bearings such as aerospace, defense, and military.

Key words: cageless ball bearing, pure rolling, dynamic characteristics, frictional self-locking, logarithmic helix