A Study on the Exponential Decay for the Bearing Defect Diagnosis 沈毓泰 南台科技大學 機械系 教授

2007/ 5/ 19 南台科大 訊號處理與機械診斷實驗室 2 Signal processing for bearing defect vibration typical of amplitude modulation 1. Introduction A single mode vibration

2007/ 5/ 19 南台科大 訊號處理與機械診斷實驗室 3 2. High frequency resonance technique The traditional signal processing band-pass filter  rectifier  low-pass filter The demodulated single

2007/ 5/ 19 南台科大 訊號處理與機械診斷實驗室 4 3. Mechanical vibration analysis The vibration signal with amplitude modulation for the bearing vibration

2007/ 5/ 19 南台科大 訊號處理與機械診斷實驗室 5 The vibration signal for the lth mode vibration would be i : the sampling point of the bearing vibration f s : the sampling frequency j : the interval number of the envelope signals

2007/ 5/ 19 南台科大 訊號處理與機械診斷實驗室 6 the number of data points is h over the j th half period 4.The envelope estimation

2007/ 5/ 19 南台科大 訊號處理與機械診斷實驗室 7 The solution obtained in a linear least squares sense would be The envelope signal would be

2007/ 5/ 19 南台科大 訊號處理與機械診斷實驗室 8 The inner-race defect case

2007/ 5/ 19 南台科大 訊號處理與機械診斷實驗室 9 The advantages the envelope estimation algorithm could theoretically retrieve several envelope signals corresponding to their mode vibrations and the envelope signals are less distorted. the envelope signals would automatically become low-sampling-rate signals.

2007/ 5/ 19 南台科大 訊號處理與機械診斷實驗室 10 it is easy in calculation to retrieve the envelope signals from a modulated vibration or even to reconstruct the modulated vibration from the envelope signals.

2007/ 5/ 19 南台科大 訊號處理與機械診斷實驗室 The estimation of exponential decay The envelope of an impulse response in the time interval,  t, could be expressed as with and would be rewritten as

2007/ 5/ 19 南台科大 訊號處理與機械診斷實驗室 12 where The solution for  l and ln( C lm )

2007/ 5/ 19 南台科大 訊號處理與機械診斷實驗室 13 5 、 Experimental Result Resonance mode  Bearing type First resonance mode Second resonance mode Third resonance mode Normal Outer-race defect Inner-race defect Roller defect Multiple defect The exponential decay for the envelope signals at running speed 800 rpm

2007/ 5/ 19 南台科大 訊號處理與機械診斷實驗室 14 Resonance mode  Bearing type First resonance mode Second resonance mode Third resonance mode Normal Outer-race defect Inner-race defect Roller defect Multiple defect The exponential decay for the envelope signals at running speed 1600 rpm

2007/ 5/ 19 南台科大 訊號處理與機械診斷實驗室 15 6 、 Conclusion an envelope estimation algorithm is carried out to retrieve the envelope signals from the corresponding resonance modes. the diagnosis index based on the exponential decay is proposed and proved effective in monitoring the bearing running condition.

2007/ 5/ 19 南台科大 訊號處理與機械診斷實驗室 16 Thank you