On-Line Monitoring Method Investigation Of Milling Cutter Breakage In The Process Of Impeller Machining

With the development of large precision machinery including aircraft engines,compressors towards high load,high efficiency and high reliability,the quality requirements of the impeller are getting higher and higher.However,as the processing technology for impeller is complex and the cutting condition is unstable,milling tool edge is broken easily in machining process,which will seriously affects the quality of impeller and increases the maching cost;so on-line monitoring on milling cutter breakage has important significance for improving processing quality and production efficiency.This paper focuses on on-line monitoring methods investigation of milling cutter breakage in the process of impeller machining;the main contents are as follows:(1)At first,the milling experiments with ball end cutter handle three is carried on CMV-850 A vertical machining center;collecting the eddy current signal of radial displacement and the milling force signal simultaneously,through the curve fitting method to verify the linear relationship between the milling force and eddy-current displacement signal of cutter radial swing.Vibration signal of acceleration sampled from X,Y direction of machine tool spindle end is transferred into vibration signal of displacement with frequency-domain integration algorithm;do the waveform similarity analysis between vibration signal of displacement and eddy current signal and discover that there is a linear correlation between them.So vibration signal of displacement can be used as monorting signal instead of the eddy current displacement signal,which solves the difficulty of eddy current sensor installation well.(2)Calculating the first-order cumulant and second-order cumulant of monitoring signal with time synchronous averaging algorithm and characterizing waveform of the cumulants quantitatively with characteristics in time domain,which include variance,skew,kurtosis,absolute mean value and RMS.At the same time,using wavelet decomposition for the selection of feature frequency optimizes the monitoring results.In the frequency domain,the milling tool condition is analyzed with the spectral structure,which is described by frequency domain characteristic;the recognition of cutter state changes could be realized based on the characteristic values.Moreover,the AR model is established for the second-order cumulant of monitoring signal and then,the distance function based on the AR model is used to identify the state of the cutter for different maching processes.(3)Based on LabVIEW platform and NI9234 data acquisition card,bridging the on-line monitoring system for milling cutter broken,which is consisted of data acquisition part and data analysis part.what's more,the monitoring system has automatic warning function based on the threshold of characteristic value and pattern recognition result.