Analysis And Experimental Study On Bearing Thermal Characteristics Of Machine Feeding System

As the mainly heat-generating component of machine tool feed system, thermal deformation of angular contact ball bearings directly affects the accuracy of machine tool feed system. Accurately predicting the bearing temperature distribution has great influence on reducing the thermal deformation of feed system. This paper has deeply researched the thermal characteristics of 60° angular contact ball bearings from the perspective of theoretical modeling, finite element analysis, experimental verification and structure optimization.Firstly, bearing friction torque and frictional heat were calculated on the basis of quasi-static angular contact ball bearings model, and deduced the intensity heating source of bearing inner ring, outer ring and balls. Then this paper analyzed the simplified method of calculating bearing relative axial and radial thermal displacement and proposed the technology roadmap of bearing thermal stiffness.Secondly, heat transfer model with thermal contact resistance and finite element model were built. Steady-state and transient temperature distribution were analyzed on the basis of deeply analyzing heat transfer coefficient of bearing assembly faces. And the influences of axial force and speed on bearing temperature distribution and thermal equilibrium time were studied. Then the impact of thermal deformation on the bearing contact stress was illustrated by the two-dimensional model of bearing heat-structure coupling analysis model.Again, bearing thermal characteristics test-bed was designed. On this test-bed, thermal distribution and axial thermal displacement of four different types of bearings were tested with different conditions. The relative errors of experimental results and analysis results were within 10%, which verified the correctness of the finite element model and the validity of test data.Finally, the temperature distribution of CNC feed system was analyzed. The results showed that the temperature of bearings was the highest. Then the temperature distribution of new feed system structure was analyzed after added two kinds of cooling measures. It certificated that this method can not only reduce bearing temperature, but also shorten the thermal equilibrium time. At last the natural frequencies of two kinds of feed system structure were compared.