Thermal behavior on motorized spindle considering bearing thermal deformation under oil-air lubrication

With the rapid development of manufacturing industry, the application of motorized spindle is more and more widely, which puts forward higher requirements for the accuracy and failure rate of motorized spindle. However, a large amount of heat will be generated in the working process, which makes the performance of motorized spindle difficult to meet the requirements, so the thermal properties of motorized spindle need to be further studied to make the dynamic behavior better. In this research, first, the characteristics of inner/outer ring curvature radius and oil film thickness were considered in the mechanical analysis of bearing. Second, a new bearing force equilibrium model including the factors of centrifugal force, gyro moment, and ring expansion was established, in which the deformation caused by centrifugal and thermal effect was separated from the deformation caused by Hertz contact, and then the force-displacement analysis was performed. Third, the heat generation and heat transfer of motorized spindle were fully analyzed and detailed based on the thermal network method, and an optimized convective heat dissipation model for bearings was proposed. In addition, the influence of the oil film thickness on the bearing displacement model was discussed. Next, Newton-Raphson method was employed to calculate the motorized spindle network model and the temperature distribution was obtained. Finally, the temperature rise test of motorized spindle was implemented with variable parameters. And the test data were analyzed and compared with the theoretical results, which indicates that thermal network model established in this investigation has a good validity and reliability.