Analysis And Prediction Of Regenerative Chatter Stability For Passive Constrained Damping Layer Composite Boring Bar

With the development of modem industry,deep hole processing is becoming more and more widely used in the fields of aerospace,automobile and other fields.The requirements for deep-hole machining quality and machining accuracy are also increasing.High precision deep hole machining is a major problem in the field of machine manufacturing.In deep hole boring machining,due to the large aspect ratio of the boring bar and small dynamic stiffness,it is easy to cause chatter vibration,which affects the machining surface quality and machining accuracy of the workpiece,and it is difficult to meet the processing technology requirements and shorten the tool life.In this thesis,passive constrained damping layer composite boring bar is taken as the research object and the dynamic model of the boring bar and the chatter stability analysis of the boring bar during boring are taken as the main research contents,with the purpose of providing theoretical basis for the prevention and suppression of the boring chatter and reducing the damage of the chatter.The main work of this article includes the following aspectsBased on the Euler-Bernoulli beam theory,the regenerative chatter dynamic model of composite boring bar is proposed,According to the model,the stability of the boring bar in the regenerative chatter is analyzed,and the chatter stability lobes of the boring bar is obtained,and the numerical integration method is used to verily the analysis results.Based on the stability lobes,the influence of ply angle and length diameter ratio on cutting stability is analyzed.According to the theory of passive control of cutting chatter,a research project of passive constrained damping layer composite boring bar is proposed.Using the theory of complex stiffness,the structure loss factor calculation model of the constrained damping layer composite boring bar is established and the structural parameters of the boring bar are optimized and analyzed.According to the theoretical analysis,the first-order natural frequency and first-order damping ratio and other dynamic characteristics of the composite boring bar with constrained layer damping are calculated.Based on the linear dynamic model of the boring bar of regenerative chatter,a dynamic model of the passive constrained damping layer composite boring bar is established.By analysis of chatter stability,the influence of material of the matrix layer,damping layer and constraint layer on the chatter stability is revealed,and the influence of the layer mode and the layer angle of the composite boring bar on the chatter stability is also revealed.The structure parameters of the constrained damping layer composite boring bar include the damping layer,the thickness of the confinement layer and the ratio of the length to diameter,which also have an important influence on the performance of the boring bar.On the basis of the chatter stability lobes analysis,the time response curve of the composite boring bar is obtained by using the numerical integration of the time delay motion equation.The proposed stability solutions are compared with those from time simulations.The feasibility of the prediction method is verified by the rule that the maximum cutting width of chatter does not occur in proportion to the dynamic stiffness of the system during the boring process.