Research On Running Accuracy And Its Characteristics Of Deep Groove Ball Bearing-Spindle System

Bearing-spindle system has been widely used in machine tool spindles, gearboxes and other types of rotating machinery. Accuracy characteristics of shaft system affects the accuracy of machine directly, with the machinery equipment has been to the high-precision, high-performance direction, and there has presented tougher challenges on how to improve the accuracy of shaft system. This paper proposed a rotation accuracy analytical model of spindle system based on accuracy research of single bearing, which provides an important theoretical basis for carrying out the research and manufacture of high-precision equipment.In this paper, a quasi-static mechanical model based on deep groove ball bearings-spindle system with considering bearing part errors was established. Then, numerical calculation, influencing factors analysis and software design was completed on the basis of model. Details are as follows:(1)It is briefly introduced the structural characteristics of ball bearings and the basic bearing analysis theory based on the deep groove ball bearing, including Hertz contact theory and raceway control theory. Meanwhile, mathematical functions which described bearing parts error based on the analysis of error condition of bearing parts was presented, including inner and outer ring raceway roundness error and ball diameter error. Therefore, a quasi-static mechanical model with five degrees of freedom which introduced bearing part error and high speed by basic analysis theory of bearing was established. This paper model is verified correctness through the comparison of the analysis result of standard bearing6312by using Romax software, Harris model and this paper model.(2)A running accuracy analysis model about double bearings-flexible spindle system is established based on the quasi-static mechanical model with five degrees of freedom of single bearing. From the model, the allocation load of bearing of the both ends and the internal load distribution can be obtained by numerical calculation. In order to obtain the index value on the spindle rotation accuracy at any point through matrix analysis and calculation, the bearing stiffness matrix is introduced into the overall system stiffness matrix by using finite element analysis method. This paper model is verified correctness through the comparison of the analysis result of same shaft system by using Romax software and this paper model. (3)The impact regularity of running accuracy is analyzed based on the spindle system analytical model from the three aspects of bearing part errors, spindle system structure parameter and working conditions, respectively. The results show that the position of a single ball with diameter error changes does not affect the running accuracy of spindle system. Ball diameter error is larger, running accuracy of spindle system is worse. Multi-ball diameter error reasonable arrangement will help improve the accuracy of shaft system. With the flaps number of the inner and outer raceway geometry error increasing, the value of running accuracy of spindle system changes cyclically. There is a mapping between number of ball and number of cycles, a certain relationship between the number of balls and flaps number of raceways error exists will help improve the accuracy of spindle system. The impact on the running accuracy of structure parameter was smaller than the effects of bearing parts error. The impact on the running accuracy of working conditions was more obviously than the effects of bearing parts error. For specific spindle system, rational radial load, axial load and load position and speed will improve the accuracy of spindle system(4)The software named "Ball Bearing and Its Spindle System Analysis Software" was developed by using Matlab GUI, has been tested to work well.