Research On Dynamic Modeling Method Of Angular Contact Ball Bearing Joint

Spindle- bearing system is one of the important components in machine tool,and its dynamic performance can affect machine tool directly,the research on Spindle-bearing system must be conducted on the foundation of a accurate dynamic model of bearing joint. In this paper,the author designed a spindle box to be the research object, and built the finite element model of the box which contained the bearing joint, model test on the spindle box was performed at the same time; according to the results, the stiffness of bearing joint was identified to optimize the model, verifying the validity of the method.Based on the point contact theory proposed by Hertz, formulas which describe the contact stiffness of single rolling ball in bearing were deduced,each ball was regarded as spring unit to simulate the bearing joint, and stiffness of the unit was acquired by the formulas proposed above. Finally,the initial finite element model was built and the modal analysis was executed.Modal impact test was performed on the spindle box, acquiring the experimental modal parameters which were used to verify the dynamic model through comparing frequencies and shapes, On the basis of the results of the comparison above, the issue of parameter identification and model optimization was put forward.According to the updating theory of finite element model, the stiffness of bearing joint was identified by using modules named sensitivity analysis and optimization of NASTRAN.Compared the parameters such as frequencies and shapes of updated model with parameters acquired from test, the results turned out to be rational enough to verify the validity of the method,finally, some further research were done to verify the generality of the method.