Study On Planetary Gearbox Fault Diagnosis Technology Based On Time Domain Synchronous Average Algorithm

Modern mechanical equipment is gradually becoming more complex,large-scale and multi-purpose.Gearbox is one of the core transmission components of rotating machinery.Its operating state plays a decisive role in the normal operation of whole system.At the same time,Planetary gearbox has a more complicated structure than fix shaft gearbox.Therefore,the fault diagnosis technology for gearbox is based on gear train with fixed shaft,and fault diagnosis technology for planetary gearbox starts late and still immature.In engineering practice,the accuracy of fault diagnosis cannot be improved due to large background noise.Therefore,the research on planetary gearbox fault diagnosis technology based on time domain synchronous averaging is of great significance.Based on the idea of synchronous average noise reduction,this paper studies torsional vibration signal of planetary gearbox and fault diagnosis technology of lateral vibration signal.The main contents are:In order to simplify the study,one-stage fix shaft gearbox which have simple vibration signal used for the reach of non-timing-pulse time synchronous averaging for signal denoising processing.A modified time-domain synchronous averaging algorithm is proposed,which solves the problem of truncation error in non-timing-pulse synchronization average algorithm.Modified algorithm greatly preserves useful information of original signal,avoiding the error of subsequent processing due to excessive loss of information.Based on LabView software,planetary gearbox signal acquisition system was developed.The incremental encoder is used to acquire torsional vibration signal,and the error of torsional vibration signal from equal angle sampling to equal time sampling is analyzed.It is found that elimination error will greatly increase calculation amount.The composition of overall components and selection of the sensors during the construction of planetary gearbox fault diagnosis experimental platform are elaborated.The acquisition system can display acquired signals in real time,the data which acquired can be saved by specified length at equal time intervals or saved by force.In addition,torsional vibration signal time domain indicators of planetary gearbox is monitored online by characteristic that torsional vibration signal is not affected by the change of rotational speed,and an alarm is issued when the gearbox is abnormal.After experimental was built,relevant experiments were carried out to study torsional vibration signal time domain and frequency domain characteristics.Experimental simulation the conditions of planetary gearbox under steady state,timevarying speed and time-varying load.Torsional vibration is different with vibration signal,it is free from time domain and identity in angular domain.There for,in engineering practice,it is easier to extract fault characteristics from torsional vibration signal.The concept of angular frequency is proposed based on the characteristics that torsional vibration signal acquired by the incremental encoder in angular domain.The central idea is: Frequency concept in analog time domain,one rotation as basic unit.the number of times periodic signal appears in one revolution of the rotating shaft is the angular frequency.The results show that torsional vibration signal based on angular frequency can still effectively extract fault characteristic frequency under large timevarying conditions.