Dynamic Characteristic Analysis And Optimization Of CXK-60 Vertical Machining Center

The distribution of the center of gravity has a large impact on the dynamic characteristics of the machining center.Therefore,to ensure good machining performance,the distribution of the center of gravity of the machining center must be within a reasonable range.Starting from the principle that the change of mass distribution will affect the natural frequency of the mechanical structure,the concept of the center of gravity area of the machining center is proposed.The method of biharmonic and spline interpolation was used to predict the change law of natural frequency in the center of gravity of machining center.Taking the column of the machining center as an example,under the premise of bionic design of leaf veins,in order to optimize the center of gravity distribution and static and dynamic characteristics of the machining center,the theoretical analysis,simulation and optimization are used to analyze the dynamic characteristics of the machining center.The main work of this article is as follows:(1)Based on the properties of Rayleigh quotient and the theoretical derivation of machine tool dynamics modification,the theoretical model of the centralized mass parameters of the machining center was established to analyze the effect on the natural frequency of the whole machine when the quality matrix changed.The concept of the center of gravity area of the machining center was proposed from the perspective of the spatial change of the relative positions of the centers of mass of the columns and beams,which provided a basis for the analysis and optimization of the dynamic characteristics of the machining center.(2)The center of gravity area of the machining center was determined by the extreme position of the headstock in the machining space,and 15 simulation points were designed therein.The first ten natural frequencies of the machining center were predicted using the finite element method and double harmonic spline interpolation analysis.The change law of the harmonious response amplitude in the center of gravity.The analysis found that the smaller the area of the center of gravity,the higher the natural frequency of the whole machine in the processing space.Based on orthogonal experimental design and range method,the influence of the structural parameter changes of the machining center column on the center of gravity distribution and the quality of the whole machine was analyzed,which provided ideas for the optimization of column structural parameters.(3)Based on the concept of bionic design,the leaf veins of plant leaves wereused as biological prototypes for bionic design,and the similarity evaluation was performed on the pillars and leaf veins using the principle of similarity..Based on the characteristics of the leaf vein structure,a finite element model of the leaf was established,and the relationship between the leaf vein structure and its static and dynamic characteristics was obtained.Finally,a model of preliminary bionic design was determined.Compared with the original column performance,it is found that the static and dynamic characteristics of the bionic design column have been improved to a certain extent,and the mass has been reduced by 257 Kg.(4)For the bionic column designed initially,the response surface method was used to analyze the influence degree of the structure parameters of the column on the response index.Based on the non-dominated sorting genetic algorithm(NSGA-II),the multi-objective optimization was performed on the four indexes of the center of gravity area,the first-order natural frequency,the maximum static deformation,and the mass of the whole machine,and the optimal combination of the structural parameters of the bionic column was obtained.Through the comparison of finite element simulation,the performance of the column and the machining center has reached a comprehensive optimum,thereby verifying the correctness of the smallest area of the center of gravity as the optimization target.