Purpose To accurately identify the role of oil film in the contact heat transfer of ball-raceway and thoroughly characterize the bearing heating, this paper aims to discuss the impact of lubricating oil film on the thermal contact transfer of bearing ball-raceway, and accordingly presents a novel comprehensive contact heat transfer model coupling the thermal dissipation of oil film and the relative motions of bearing ball-oil film-raceway as well. Design/methodology/approach The Hertz contact of ball-raceway was first analyzed, and how the relative motions between the oil film, bearing ball and raceway affect the thermal dissipation of oil film also was discussed. The oil film thermal exchanges induced by the rolling and spin of bearing balls accordingly were modeled. To further integrate the heat conduction inside oil film, a novel heat transfer network of bearing oil film was constructed, and its thermal equivalent resistance was derived. A novel comprehensive thermal contact transfer model of ball-raceway with the Hertz contact and oil film impacts next was proposed, by which an improved bearing thermal network under oil-air two-phase separation was planned. In the meantime, this newly proposed bearing model, for proving the above findings, was used to arrange a thermal grid for the selected motorized spindle. The thermal changes with or no oil film effect were both simulated. The corresponding numerical results under different operation conditions were also contrasted with the corresponding test values for validation. Findings This paper explores the lubrication oil film effect on the contact heat transfer of bearing ball-raceway. The results indicate that the bearing heating is partly influenced by the oil film. For a more precise thermal forecasting, it needs to be factored. Originality/value The oil film impacts on the thermal transmission of ball-raceway are discussed in detail and assessed separately, and accordingly a novel equivalent thermal grid of oil film is presented. A comprehensive thermal contact transfer model, meanwhile, is constructed for the first time to thoroughly characterize the thermal contact transfer of ball-raceway.
Zheng et al. (Tue,) studied this question.