Research On Condition Monitoring Of Lathe Tools Based On Motor Current Signal Analysis

In the modern production and processing,lathe processing occupies a large proportion,and tool condition is one of the most important factors that influence its quality.In this case,the monitoring of tool condition is an efficient way to improve the quality of production.By monitoring of tool,wearing can be recognized early,so that we can change the tool in advance before failures,which can greatly improve the production efficiency,and reduce defective rate.At present,the tool condition monitoring method includes vibration,cutting force and current signal analysis.Compared with others,current signal analysis has the advantages of low cost and no need to make extra transform to the lathe,so that it is now being used widely in production.Motor current signal analysis is a method of condition monitoring based on current signal.In this paper,we made test on tool wear test platform,by analyzing the current of spindle motor,we can determine the condition of lathe and tool.The main contents are as follows:(1)By decomposing the current signal using wavelet packet,and comparing the energy of each frequency band,we can select the band which contains the information of tool condition,and then extract the sensitive feature,which can be considered as an indicator to the tool condition.(2)Using linear discriminant analysis to reduce the dimension of feature,and to get a set of new indicator that contain all the feature extracted.The optimized indicator has the largest between-class distance and smallest inner-class distance.Use B spline fitting to establish a model of the tool wearing.(3)Using SVM to judge whether the tool is wore,and to determine the threshold value of indicator,So that the system can make alarm before tool wear.The result showed that,the method proposed in the paper can well recognize the tool condition.The final accuracy is above 90%...