Application Of On-line Monitoring And Fault Diagnosis For Gearbox Of Large Fan

Fan is mainly used to ventilate in the fields of petrochemical,metallurgy,electric power,textile,ship,urban rail transit and other areas of the national economy and various areas.The operating environment and working conditions of the fan are generally harsh with continuous production,which leads to the fan is frequently failed.As an important transmission component,gearbox is also a component with multiple faults.Therefore,online monitoring and fault diagnosis research on gearbox of large fan can effectively avoid sudden accidents caused by faults and reduce unnecessary economic losses.To resolve the problems mentioned above,gear box of large fan is taken as the research object in this paper.The vibration sensor is adopted to extract the vibration signal of the gear box's component fault and the principal component analysis method is applied to dimensional reduction of dimensionless parameters,and then carries on the fault diagnosis of the gear box to realize the online monitor of the large fan gear box.The main contents of this paper are as follows:(1)To understand the basic structure of fan and gear box,the proportion of failure of each part of gear box and its main failure form are investigated in detail,and the vibration signal model and fault characteristics of gear and rolling bearing under the state of failure are also discussed in this paper.(2)Based on the commonly used fault diagnosis methods and signal processing methods,the advantages and disadvantages of various methods are reviewed,which provides theoretical basis for online monitoring and fault diagnosis of large fan gearbox.(3)With consideration of the environmental impact on the fan site and the original fault vibration signal is the non-stationary and non-linear weak signal,the dimensionless indicator with low sensitivity to the working environment is selected for diagnosis.Vibration data are measured with laboratory units,and then data processing is carried out to obtain multi-dimensional dimensionless indicators,to judge whether the gearbox failure or not.Because there are some overlaps between multi-dimensional dimensionless indicators and the calculation is too large,the principal component analysis method is adopted.The validity of the principal component analysis method is verified by the test data.(4)Based on the research foundation of laboratory gearbox and the existing test conditions,an on-line monitoring example was carried out to validate the experimental unit.Two sensors were used to test the normal condition,gear wear,gear broken teeth,gear pitting corrosion,gear crack,bearing inner ring wear,bearing outer ring wear and cage broken gluing at 1200 r/min speed.The principal component analysis was applied to improve the performance of the system.By dimension reduction,100% of the abnormalities can be distinguished,and 5 kinds of faults in the abnormalities can be clearly distinguished.The accuracy rate is 75%.Therefore,it can be applied to on-line monitoring and fault diagnosis of industrial fan gearbox.