Research On Dynamic Characteristics And Parameters Optimization Of Angular Contact Ball Bearings Based On Fit Tolerance

The motorized spindle is the key function part of machine tools for driving the cutting tool into rotating, to achieve high-efficiency and precision machining, its performance decides the performance and technology level of the high-speed machine in a high degree. Angular contact ball bearing as an important support element of the electric spindle, its fit tolerance, centrifugal force deformation, thermal deformation, ferrule deformation, elastohydrodynamic lubrication and structure parameters directly affect the dynamic performance, machining precision and machining quality of motorized spindle. At present, the research on analysing the dynamic character of bearings considering influencing factors are lacking in systematic research, it is necessary to make a further study on modeling and optimizating dynamic characteristics parameters of angular contact ball bearings based on fit tolerance.The mathematics model for calculating interference fit is created by the derived expression of interference fit and contact angle after bearing having been mounted on the shaft and housing. Based on the changes in geometry position of bearing inner raceway curvature center and the rolling body center caused by bearing ferrule deformation and elastohydrodynamic lubrication effect, a quasi-static correction model for angular contact ball bearing considering the effect of ferrule deformation and elastohydrodynamic lubrication is established. The dynamic characteristics of bearing are analyzed by the Newton-Raphson numerical analysis method based on the solved nonlinear equations. And on this basis, the effect of interference fit on the contact angle, the contact force, the surface contactstresses, the dynamic stiffness, the ratio of revolution and rolling by bearing are simulated. The effect of thermal deformation, the centrifugal force deformation and the lubricating oil film on bearing dynamic stiffness under conditions of different rotational speed and bearing preload is quantitative studied by established model, overcome the shortage of traditional quasi-static analytical method which does not consider the influencing factors.The software of structural parameter analysis and dynamic characteristic optimum design is developed(No2014SR108520). The validity of the established model is verified by comparison with the Gupta typical examples. The influence of the rolling element material,the diameter of rolling body,the number of sphere,the contact angle and the ring raceway between inner and outer rings on bearing dynamic characteristics are studied by the software. Specific methods of bearing performance parameter optimization is proposed with the view of improving the dynamic stiffness and fatigue life of bearings. The result is shown that the spherical ceramic particles can actually be more useful in improving the rotational speed, stiffness and self-lubricating ability of bearings, bearing load capacity can be raised by reducing diameter of the rolling body, properly increasing the number of sphere, decreasing the dynamic contact angle can effectively reducing the impact of spin friction and gyratory motion by the ball rolling element, a large bearing inner ring raceway and a small bearing outer ring raceway can reduce the friction and heat, improve the rotational speed.Experimental study on the dynamic properties of high-speed cutting machines spindle 62YGC1.0-60 is carried out. The accuracy of created model and analysis methods were verified by comparing with the test data on hammer experiment.The proposed model and related research results have an important referenced value for the dynamic performance analysis and dynamic characteristics parameters optimization of bearings.