Research On Dynamics Modeling Method And Spring Stiffness Identification Of Machine Bolt Joints

Dynamic performances of machine tools are largely influenced by the properties of bolt joints, accurately modeling the joints is the premise of studying dynamic properties of the joints and optimal designing. In this dissertation, the methods of modeling bolt joints dynamics are studied, and identify the spring stiffness of the dynamic model, then according to the idea of Yoshimura masataka of solving the spring stiffness, transform the spring stiffness of the single faceted joints to the spring stiffness of the double faceted joints, finally bolt joints dynamics of MCH63are modeled. Also provides an idea to model the bolt joints of machine tools.In this article dynamics model of bolt joints consist of modeling and solving the dynamic stiffness.On the basis of studying the conditions of modeling bolt joints dynamics, modeling methods of spring units uniformly distributed and3spring units circumferentially distributed are studied by the finite element modal analysis, the modeling method of3spring units circumferentially distributed reduce the number of spring elements in the process of bolt joints dynamic modeling, ensure the accuracy of modeling dynamic models. The results show that3spring units circumferentially distributed dynamics model improves the efficiency of the modeling and calculation.Identify the dynamic stiffness of the single faceted joints by adopting the combination of modal analysis and experiment test method, and verify the correctness of the identification method. The spring stiffness of spring units uniformly distributed and3spring units circumferentially distributed are identified by using this identification method. Finally, further verify the correctness of the modeling method of3spring units circumferentially distributed and the feasibility in the practical application.On the basis of the above identify the dynamic stiffness, according to the idea of Yoshimura masataka of solving the spring stiffness and the same conditions of bolt joints, transform the dynamic stiffness of the single faceted joints to the dynamic stiffness of the double faceted joints, compare the results of finite element analysis and experimental test, then certify this method is effective. Eventually typical bolt joints dynamics of MCH63are established based on the modeling method of3spring units circumferentially distributed and dynamic stiffness conversion method.Experimental results show that the method described in this article, especially3spring units circumferentially distributed dynamics model can effectively solve bolt joints dynamics of machine tool in the engineering practice.