Uneven heat generation and thermal performance of spindle bearings

The force that an angular contact ball bearing suffered is non-uniform due to the radial loading of an operating spindle, which leads to more heat generation in the contact zone. To this end of improving spindle thermal characteristics, non-uniform preload adjusting method was employed. Firstly, a novel quasi-static five-degrees-of-freedom model for an angular contact ball bearing under rigid axial preload was deduced, then a local bearing heat-generation power model was employed to assess power losses in different contact zones, in which bearing contact parameters, external loads, rotation speeds, and bearing preload conditions were fully considered. Additionally, variance analysis was used to estimate heat generation fluctuations in bearing local contact zone. Finally, an adjustable preload platform was designed and thermal features of uniform and non-uniform preload were discussed. The results show that, a suitable non-uniform preload for operating spindle can reduce bearing temperatures by 15.4% at most.