Fault Size Estimate Of Roller Bearings Based On Double Impulse Characteristic Method

Rolling element bearing is one of the important parts of rotating machinery.Once the fault occurring,which will cause the equipment failures and even lead to the casualties.Therefore,it is significantly important to find out the early fault of the rolling bearing and get the information of the fault expansion degree in order to eliminate the hidden trouble and guarantee the safe operation of the equipment.At present,it is difficult to determine the degree of fault propagation of rolling element bearings.To overcome this problem,based on the double impact phenomenon caused by the rolling elements passing the defect edge,according to the corresponding relationship between the signal waveform and the running state of the bearing,this thesis proposes a method of fault size estimate of bearings based on double impulse characteristic method.The main contents of this thesis are as follows:(1)The fault diagnosis method of rolling bearings with ARMED and Teager energy operator is proposed.The vibration mechanism of rolling element bearing is investigated.According to the characteristics of local defect vibration signal,the ARMED algorithm is used to deconvolution the periodic impulse due to the fault.The fault component from the high frequency carrier component is demodulated by the energy operator.The energy spectrum of the fault component is analyzed,and the fault location and fault type are determined accurately.(2)A double impact extraction method based on AR model and Symlet wavelet is proposed.The phenomenon and mechanism of double impact that caused by the collision of the rolling element with the edge of the defect is analyzed.Based on the characteristics of different filters,the AR filter is used to filter the periodic natural frequency components in the original signal.The energy operator is used to weaken the influence of the background noise and the interference of the random impact.The discrete wavelet transform is used to decompose and reconstruct the signal,and the accurate extraction of double impact feature in mixed signal is realized.The impulse response function,the step response function and noise are constructed to simulate the double pulse signal of bearing with outer race defect.The proposed method is used to accurately extract the double impact components in the simulation signal,and the validity of the method is verified,which provides the foundation and way for further estimating the size of the defect.(3)A new method based on double impulse response to estimate the fault size of bearings is proposed.The relationship between the characteristics of the double impact signal and the position of the rolling element passing through the defect region is discussed.The influence of rolling elements sliding on the defect size estimation is considered,based on the kinematics of the rolling element bearing and the time information from the double impact signal,the calculation formula of the defect size is deduced.Through a series of defect experiments for the outer race at different rotational speed,the correctness and rationality of the proposed method for the identification of the defect location and the degree of defect of the rolling bearing are verified.