Study On The Chatter Mechanism And Stability Of Hardened Die Steel Cr12MoV For High-speed Milling

For a long time,high efficiency and precision machining of complex surface of automobile panel die is a difficult technological problem in domestic and foreign advanced manufacturing field,which is mainly due to the poor performance and incidental chatter of processing technology for the hardened steel mold.As an unstable phenomenon that often occurs in the milling process,chatter seriously restricts the surface quality and production efficiency of hardened mould,besides,it may cause the tool to collapse and even a severe damage of the machine tool spindle.Therefore,the research on the milling stability of hardened steel mold becomes more and more important and cannot be ignored.This paper mainly studied the vertical milling process of Cr12 MoV,the main contents are as follows.1)Firstly,on the basis of the most mature and popular instantaneous rigid force model,the research model of the milling force coefficient is established.The simulation data is processed through the range analysis method,and the order of the milling parameters on milling force is given.The influence of the main factors on milling force is analyzed,which provides a reliable theoretical support for the practical application.And then,considering the disadvantages of large experimental quantity and low prediction precision of the current milling force coefficient test method,simulation analysis is carried out by the linear increase of the feed per tooth taking the analytical method as the main method and using the MATLAB.The rapid calibration of the milling force coefficient is completed,which provides a necessary data basis for the subsequent research of the milling chatter.2)First of all,on the basis of the dynamic milling force model taking the consideration of the effect of regeneration,the milling stability prediction model is established by using the ZOA method.Then,the amplitude-frequency characteristic curve of process system is obtained by the hammer test,and the modal parameters are identified based on the analysis software LMS Test.Lab.Finally,the milling chatter stability diagram of classical linear model is given through the way of programming.Meanwhile,the influence of modal parameters on chatter is simulated and analyzed,which provides reference for the stable milling of hardened die steel Cr12 MoV.3)The nonlinear factors existed in actual processing constrain the stability of milling directly.For this reason,the stability nonlinear prediction model considering process damping is first established.On the basis of the model and the time domain analysis theory,the semi-discrete numerical method is used to draw the stability lobes diagram.The results show that the ultimate depth of the low speed region is obviously improved when the process damping is taken into consideration.And then,the influence of modal parameters and indentation force coefficient on the milling stability of Cr12 MoV is studied,which provides a technical support for effectivelysolving the problem of the improper selection for process parameters caused by the compact SLD in low speed region.