Research On Modeling And Dynamic Characteristics Of Cutterhead Cutting System Of High-Precision Centerless Lathe

High-precision centerless lathe is a kind of equipment that removes the surface oxide layer and crack defects of long-circle metal bars,like tubes,rods,ect.It is widely used owing to its high progress and high efficiency.The cutterhead cutting system is the system that has a more direct impact on the machining accuracy among other systems of the centerless lathe.The cutterhead cutting system contacts with the workpieces directly during the cutting process,and its performance affects the machining accuracy of the machine tool and surface machining quality of the workpieces.Taking the cutterhead cutting system of high-precision centerless lathe as the research object,The thesis aims to make an in-depth research on the modeling and dynamic characteristics of the cutterhead cutting system.The major research contents are as follows:(1)In view of the dynamics research of the cutterhead cutting system,firstly,the its operational principle and structure require elucidating,and then the mechanical analysis of the cutterhead cutting system is carried out.Based on the D'Alembert principle,the thesis established the dynamic differential equation of the cutterhead cutting system and made an analysis of the system dynamics to obtain its transfer function of the dynamic response,which provides a theoretical basis for the dynamic research of the cutterhead cutting system.(2)Take the cutterhead cutting system of the centerless lathe as the modeling object,the thesis established the three-dimensional model and finite element model of the system according to the actual size of the cutterhead cutting system and so lved the cutting load of the system by the empirical formula.And then the finite element analysis software ABAQUS was employed to perform a static analysis on the cutterhead cutting system and the deformation of the cutterhead cutting system in the x,y and z directions was obtained through simulation analysis to solve the stiffness of the system.(3)The thesis makes a modal analysis of the cutterhead cutting system in the free state and the constrained state.Firstly,the modal parameters are solved to obtain the first 12 natural frequencies and modal cloud diagrams of the free mode and the constrained mode of the cutterhead cutting system.Secondly,a comparative analysis of the free mode and the constrained mode in the cutterhead cutting system are made to obtain the constrained mode analysis closer to the real situation of the system.Finally,the Campbell graph is used to solve the critical revolutions corresponding to the natural frequencies of the cutterhead cutting system.(4)On the premise of the modal analysis,the research,based on the harmonic response analysis theory,tries to make a harmonic response analysis of the cutterhead cutting system with a sweep frequency range of 0?550 Hz.And then it extracts the frequency response curve of the six nodes with the largest deformation displacement in the key position of the cutterhead cutting system.It finally concludes that the cutterhead cutting system will cause resonance in the load frequency range of 276 Hz,354 Hz,440 Hz and 490 Hz,and the resonance peak at the first-order natural frequency reaches the maximum;Last but not least,the harmonic response analysis of the cutterhead cutting system under four common operating conditions is carried out,and the amplitude-frequency harmonic response curve shows that the most accurate cutting process is at a speed of 480 r/min,which is consistent with the actual cutting experiment results.