The Study On Cr13 Milling With Ball End Milling Cutter Process Flutter Stability

Milling technology has been widely used in mechanical manufacturing because of its advantages of high efficiency and accuracy of surface machining.With the development of manufacturing industry,the stability of machining is required higher and higher.The milling process is intermittent cutting,and the cutter tooth participates in machining periodically.So it is easy to produce vibration because of the dynamic milling in the machining process,which will affect the machining quality,machine tool and tool life,and seriously bring danger to the production process.Cr13 stainless steel is the main component material of impulse turbine,which is difficult to process.Therefore,studying the flutter stability in machining and optimizing machining parameters based on the study.It is meaningful to improve its machining effect,product processing quality and efficiency.The study using ball end milling cutter as the research object,and the milling process is simulated.The milling stability of Cr13 is studied as follows.（1）The mathematical and geometric structure of ball end milling cutter is analyzed,and the geometric equation of the helix of the milling edge of ball end milling cutter is put forward.The mathematical model of micro element milling force of ball end milling cutter is constructed by using the instantaneous rigid force model.In the end,the overall milling force model of milling cutter is obtained after calculation.Milling is generally divided into forward milling and reverse milling.According to the axial position of the tool and workpiece,the calculation of the entry angle and exit angle of the two machining methods are expressed.（2）Based on the average milling force coefficient method,the full tooth cutting experiment is carried out,and the cutting force coefficient is identified by linear regression method.The milling force simulation program is compiled to simulate the milling force and the milling force is simulated and predicted,verifying the accuracy of the milling force model and the milling force coefficient.The effects of axial cutting depth and feed rate per tooth on the milling force are analyzed.It shows that the milling force will increase with the increase of axial cutting depth and feed rate per tooth.（3）Through the mechanism of regenerative chatter,the influence of chatter on dynamic milling thickness and dynamic milling force is analyzed,and the dynamic milling thickness and milling force are expressed.The experimental modal analysis of the machining system is carried out,the modal parameters of the machining system are identified by using the obtained data,and simulating the dynamic milling force in the machining process.It shows that the milling force changes periodically in the stable machining state.（4）The two degree of freedom vibration differential equation considering regenerative flutter is solved by semi discrete time domain method to obtain the stability limit diagram.The influence of the characteristic parameters of the system（stiffness,natural frequency and damping ratio）on the stability region is analyzed respectively.It is concluded that the machining stability and efficiency can be improved by improving the stiffness,natural frequency and damping ratio of the system.Using the fourth-order Runge-Kutta algorithm,the state of the points on the stability limit diagram is judged,and the two results are consistent,which verifies the accuracy of the stability limit diagram.