Research And Implementation Of Tooth Failure Monitoring Based On Spindle Motor Current

Tool breakage has influence on the workpiece machining accuracy, surface quality, andleads to machine vibration, noise and other unpredictable consequences.For many years,therehave been various research on themonitoring of tool breakage, but all are in the studystage.Existing methods of tool breakage monitoringare hardly suitable for mass production ofcutting parameter fluctuation.This paper presents a tool breakagemonitoringmethodwhichbased on the analysis of spindle motor current signals. The main research contents areas follows:According to the practical situation in milling, the principle of tooth failure monitoringhas been put forward and the tooth failure monitoring experiment scheme was designed basedon the principle.Through thecomparisonof spindle motor current signal and cutting force signal both ontime domain and frequency domain, characteristic signalswhich can be used to monitor thetooth failure of tool during cutting processare found. According to the research of spindlemotor current signal, the properties of time domain and frequency domain and the pattern ofcurrent signal change before during after the process of tooth failure are summarized. Amathematical model which describes the process of tooth failure based on spindle motorcurrent is established.By using the method of cutting cycle residue, characteristic signal during the moment oftooth failure is extracted. At the same time, by using wavelet packet analysis, spindle motorcurrent signal is decomposed and feature frequency band signals which are characterize thenumber and the relative position of the failuretooth are extracted. Through the experimentsunder condition of different processing parameter, the effectiveness of characteristic signalextraction methods is validated.Finally, through the combination of tooth failure monitoring technology and embeddedtechnology,an embedded system of tooth failure monitoring is developed. This system notonly can collect, display and store data, but also can use cutting cycle residue method and themethod of frequency domain to the analyze spindle motor current signal in real time tomonitor the tooth breakage during cutting process.