A Review of Mesoscopic Damage and Its Discrete Performance in Local Functional Grooves of Cageless Ball Bearings

Cageless ball bearings, due to their larger number of rolling elements and stronger load-bearing capacity, are widely used in active magnetic bearing systems, serving as protective bearings. However, due to the lack of traditional cages to isolate adjacent rolling elements in cageless ball bearings, cumulative collisions are inevitable, leading to severe friction and heating. Although scholars have proposed using cageless ball bearings with local functional grooves as protective bearings for magnetic bearings, and conducted relevant theoretical and experimental research on them, the impact of bearing wear with local functional grooves on the dispersion effect remains to be studied. Wear of local functional grooves can cause their edges to expand outward, altering the contact radius between the rolling elements and the grooves. This change also affects the orbital velocity of the rolling elements passing through the grooves, leading to collisions between adjacent rolling elements. In severe cases, this can result in the rolling elements failing due to self-dispersion. By studying the impact of the degree of damage to local functional grooves on the self-dispersion behavior of rolling elements, we can assess the lifespan of protective bearings, facilitating timely replacement and reducing major accidents and economic losses caused by bearing failure.