Research On The On-line Monitoring And Fault Diagnosis Of High Speed Finishing Mill

The finishing mill is the key part of high speed rolling mill. The working condition and fault trends can be predicted by the on-line monitoring and fault diagnosis system, which is very important to ensure the safety in production. The gear-box is the key part of finishing mill, and the fault diagnosis of gearbox has important engineering applying worthness as it can reduce the maintenance costs and improve the product quality. The work accomplished in this thesis is as follows:Frist, aiming at the rolling mill gearbox, the fault mode, characteristic frequency of rolling bearing and gear are discussed; the mechanism of amplitude and frequency modulation of vibration signal in gearbox is introduced. As an example, the characteristic frequencies of a certain finishing mill in Shougang Group are calculated.Second, the feature extraction methods of vibration signals are expatiated, which mainly include waveform analysis, statistics index, amplitude spectrum, autocorrelation analysis and wavelet transformation. The theory foundation was built for the on-line monitoring system development and fault diagnosis.Thirdly, considering the peculiarity of high speed rolling mill gearbox, the scheme of on-line monitoring system is designed and the on-line monitoring system is finished. The whole system consists of equipments management module, signal sampled module and on-line monitoring module, and the working condition of finishing mill can be distinctly expressed by the statistics index, waveform, spectrum,trends, and so on.Last, applying the on-line monitoring system in the ShouGang Group high speed rolling mill factory, the bearing inner ring corrosion and teeth broken fault of gear-box were successfully diagnosed, and the malignant accident was avoided.