Research On Dynamic Characteristics Of The Whole Machine Tool Based On Dynamic Stiffness Sensitivity

With the development of advanced manufacturing technology,the dynamics of machine tools which have little influence on machining progresses under the traditional processing conditions have become the bottle neck factor,which seriously hinders improvement of the performance of high-end CNC machine tools.After the space position of the machine tool changes,the mass matrix,stiffness matrix and damping matrix of the system all change,so the dynamic characteristics of the machine tool will change.However,there are some limitations in the current research on the whole machine tool dynamics: Firstly,for the set of vibration response of full space position,the traditional modal analysis method is inefficient.Secondly,the modal parameters are not combined with the differences among the parts of the machine tool,so it is difficult to directly express the whole machine tool dynamics.Finally,the vibration characteristic of the machine tool is the result of the coupling effect of the whole machine tool dynamics and the cutting force.Therefore,this paper focuses on the machining process of machine tools,and carries out foundation theoretical and experimental research of the whole machine tool dynamics.Firstly,the clustering method is used to reduce the vibration response data set of full space position.The vibration response data set is established by multi-axis joint self-excitation,the vibration characteristics of the gravity-frequency are extracted,the dynamic parameter set of the position marker is obtained by the clustering analysis and operational modal analysisThen,an algorithm for identifying sensitive parts with dynamic stiffness sensitivity is proposed,and the dominant modes of the sensitive parts is used to express the whole machine tool dynamics of the position correlation,which make up for the deficiency that the modal parameters are difficult to directly express the whole machine tool dynamics.Finally,according to the method of Operational Deflection Shapes,the contribution of each mode to the vibration is identified,and the influence of cutting incentive force on the key modes and structural vibration characteristics of sensitive parts is studied under the dynamic characteristics of the machine tool.In this paper,clustering reduction of vibration response data,dynamic stiffness sensitivity algorithm,and the modal contribution recognition based on Operational Deflection Shapes are applied to express the whole machine tool dynamics of position-related and part-related,as well as to optimize the cutting parameters and predict the process stability,which is of great significance to improve processing quality,processing efficiency and intelligent monitoring.