Research On Cutting Stability Of High Speed And High Precision Machining Center

As an important part of the manufacturing industry,milling processing has been studied and paid attention to by many scholars at home and abroad.As a periodic discontinuous processing method,it is easy to cause chattering during the cutting process,Such unfavorable factors seriously reduce the machining quality and efficiency of machine tools,aggravate the wear of machine tools and cutting tools,and seriously restrict the development of milling.In order to effectively prevent and control the chatter phenomenon during the milling process,a reasonable selection of processing parameters is the key to solving the chatter problem.The main content of this paper is to predict the stability of the milling process to prevent the occurrence of chatter based on the chatter theory and dynamics theory.And on the basis of preventing chatter,an optimized parameter model of the maximum material removal rate and tool cost has been established,so that the content of the stability prediction of chatter is more in line with actual needs.The method of differential integration is used to solve the cutting force,and the change law of the cutting force during down milling and up milling is obtained through computer simulation.A dynamic cutting thickness model was constructed to solve the vibration differential equations on two degrees of freedom,and the influence of the radial cutting force coefficient and the contact angle on the average direction was simulated in the computer.Analyze the influence of spindle bearing stiffness on cutting stability,and perform modal analysis and harmonious response analysis on the spindle through finite element software,The bearing stiffness is replaced by the equivalent spring stiffness,and the first six modes of the bearing and the harmonic response analysis curve under different stiffness are solved,The result proves that the overall natural frequency of the spindle system increases with the increase of the bearing stiffness,and the cutting stability is enhanced.Use the analytical method to compile simulation algorithms to draw the stability lobe diagram,and analyze the influence of the machine's natural frequency,damping ratio,stiffness,number of tool teeth and workpiece material on cutting stabilityThe influence of regeneration effect and process damping effect on stability is considered in the complete discrete method,The changes of the stable lobe diagram with and without process damping are simulated respectively,and it is concluded that considering the process damping will increase the stable area of the lobe diagram in the low-speed cutting area;At the same time,the influence of the tool immersion ratio on the lobe diagram under different helix angles is also analyzed,and it is concluded that increasing the immersion ratio will increase the possibility of chatter vibration of the machine tool system during the cutting process.On the basis of no flutter,the maximum removal rate of the material and the smallest processing cost are obtained,and the semi-discrete method is established as the dynamic constraint condition for no flutter.Constructed a comprehensive weighted function model of material removal rate,tool cost and energy consumption of machine tool,Constraint conditions such as the spindle speed,axial cutting force coefficient,radial cutting force coefficient,surface roughness and spindle power of the machine tool,Realize parameter optimization under the condition of no flutter by using simulated annealing algorithm for global optimization of the weighting function.