Effect of temperature rise on a tandem of ball-bearings with an O-configuration in motorized spindle under oil-air lubrication

Accurately predicting the thermal behavior of motorized spindles is a critical task in manufacturing industry. In this study, a thermo-mechanical-solid coupling-behavior on the motorized spindle in working condition was investigated and analyzed. Firstly, the bearing mechanical analysis of the motorized spindle under assembly constraints was discussed and a new coupling model was founded. Concurrently, the impacts of oil film thickness and the spacing rings on the displacement were considered into this model. Secondly, for the deformation of bearing, combined with Jones-Harris's quasi-static force–deformation bearing model, a mathematical model about a tandem of ball-bearings was built. And in this model, a new analytical method was proposed to decouple the deformation generated by thermal and centrifugal forces from the Hertz contact deformation, making the deformation analysis clear and orderly. Thirdly, from the perspective of heat generation mechanism and principle, based on the above bearing model, the elastohydrodynamic lubrication analysis on the bearing was executed, the thermal network model of bearing with multiple heat sources was set up, and the bearing node's scheme was optimized. Eventually, the effects of parameters such as speed, cooling water flow, and air flow on temperature rise and bearing parameters were calculated and analyzed, and the theoretical results were examined by tests, which provides some reference and guidance for the structural design of precision spindle.