The Nonlinear Vibration Characteristics Analysis In Hardened Steel Milling Chatter Produce Process

The proportion of premium automobile covering gradually increase andhardened steel material is widely used in the field of automotive industry;however but hardened steel molds of automobile large covering havecharacteristics of complex surface, high hardness and impact load. However, asthe features of complex shapes, high hardness and impact force as well, all maycause vibration especially the chatter generated in the process of milling whichaffects the quality of the machined surface, tool life and the machine lifeseriously. Therefore, this article advanced the following research for monitoringmilling chatter by analyzing vibration nonlinear characteristics in milling chatterprocess:Firstly, in order to solve the vibration problem in the hardened steel millingprocess, the relationship between milling parameters and vibration amplitude,milling force was researched based on the vibration testing (orthogonalexperiment and single factor experiment of ball end milling, workpiece materialis hardened steel), and get empirical formula of milling force and changes of thevibration milling, which provide basis for the parameters selection.Secondly, in order to solve the chatter problem in the hardened steel millingprocess, methods of feature extraction is taken to analysis milling characteristics,such as methods of time-domain, frequency domain, phase, and nonlinear chatterparameters (Maximum Lyapunov exponent and Permutation entropy). ByComparing the sensitivity of different characteristic parameters for millingchatter signal, the research show that phase characteristics can effectively detectthe status of the milling chatter, but it is not sensitive to chaos vibration in themilling process; however, the method of nonlinear characteristic parameter makeup for its shortcomings, and tested is advanced to verify the validity of the analytical method.Then, as the sensitivity of different characteristic parameters for millingchatter signal is different, KPCA analysis method is used to analyze thecharacteristics of different milling states. The research show that the extractednonlinear features have better performance in detecting chatter and an effectivelydetect the status of the milling chatter. Milling chatter status is detected bycombination of KPCA and SVM, and the analysis method of KPCA and KPCA-SVM can effectively detect nonlinear characteristic of different milling chatterstate.At last, based on the virtual instrument platform and studies of millingchatter detection method in this paper, the software of milling chatter detectionsystem is build by LabVIEW, realizing the function of real-time acquisition,analysis and pattern recognition to milling chatter, and then online forecastmilling chatter.Research of this paper can guide milling to selection parameter ball end mill,which workpiece material is hardened steel and the tool is the ball end mill.Provide basis and platform for the detection of milling chatter.