Study On The Chatter Stability And Process Optimization Of Non-uniform Allowance Milling Of Thin-walled Parts With Complex Curved Surface

Complex curved surface thin-walled parts play a very important role in the field of aerospace and other equipment manufacturing industry.In the five axis NC machining process,it is easy to produce milling chatter,which seriously affects the machining quality and surface accuracy of thin-walled parts,and then affects the working performance of complex curved surface thin-walled parts.At present,the flutter suppression of thin-walled parts with complex curved surface has become the difficulty and focus of many scholars.In this paper,the weak stiffness of complex curved surface is studied to reduce the chatter of thin-walled parts in the manufacturing process.Based on the process optimization strategy of non-uniform allowance proposed by the research group,the root cause of chatter suppression is explored.The dynamic model of machine tool tool complex curved surface thin wall milling is established,and the three-dimensional dynamic milling force of ball end milling cutter is simulated.Based on the frequency domain method proposed by Altintas,Considering the vibration in Z direction,the model of dynamic milling thickness and dynamic milling force of thin-walled parts is established.With the help of Advantage,the three-dimensional milling force is obtained and the linear regression of three-dimensional milling force is carried out,and a method of obtaining milling force coefficient by simulation analysis is proposed.The modal analysis of the whole machine tool and machine tool workpiece system is carried out,and the weak rigidity of the workpiece is taken into account,and the modal parameters of the whole machine tool workpiece machining system are quickly obtained.The high-order term of the Fourier series expansion of the time-varying periodic force coefficient matrix and the cross transfer function term of the tool workpiece contact area of the machining system are ignored.Based on the zero order frequency-domain regenerative flutter analysis theory,the dynamic model of the complex curved thin-walled parts is established,and the milling flutter stability domain of both the uniform allowance and non-uniform allowance blades are constructed.It is found that the modal stiffness and damping ratio of the blade with non-uniform allowance are larger than that of the blade with uniform allowance,and the limit cutting depth of the blade with non-uniform allowance is about 2 times of that of the blade with uniform allowance.Finally,the feasibility and effectiveness of the process optimization design of the non-uniformallowance are verified by cutting experiments.It has a guiding significance for the milling chatter produced in the actual production and processing of thin-walled parts with complex curved surface.