| As an important part of mechanical system,gear reduction box is prone to failure under high load conditions.Therefore,it is of great significance to study the condition detection and fault diagnosis of gear reduction box to ensure the stable and safe operation of equipment.At present,most contact methods such as acceleration sensors are used in fault signal detection of gear reduction boxes,which affect the effectiveness of fault detection to a certain extent.In this paper,the sinusoidal phase modulation laser interferometer is successfully applied to the fault diagnosis of small planetary gear reduction box.The method belongs to non-contact detection method,which not only does not bring any damage to the gear reduction box surface,but also has the advantages of high precision and fast response.According to fault signal detection,signal demodulation,fault recognition and classification,this paper realizes fault diagnosis of gear reduction box.The main research contents are as follows:(1)The vibration mechanism of gear transmission system is analyzed,the dynamic model of gear vibration is established,and then the modulation phenomenon of laser detection signal caused by fault vibration is analyzed,and the working principle of sinusoidal phase modulation laser interferometer is expounded.(2)Aiming at the problem that the traditional PGC demodulation algorithm is prone to nonlinear error due to carrier phase delay and modulation depth change,an improved PGC-DCM algorithm based on orthogonal signal prenormalization is proposed.The improved PGC-DCM algorithm is used to calculate the phase modulation depth and carrier phase delay,and then the orthogonal interference signal component is pre-normalized,and the visibility coefficient of interference fringe is eliminated by calculation,and the orthogonal interference signal component is fully normalized.Then the differential cross multiplication principle is used to realize the phase demodulation of interference signal.The effectiveness of the improved PGC-DCM algorithm is verified by numerical simulation and experimental test.The total harmonic distortion is-114.23 d B and the signal noise to distortion ratio is 52.70 d B.The dynamic range of the system is simulated and analyzed.In the frequency range of 200-3000 Hz,the dynamic range can reach [41.35 d B,76.88 d B].(3)In order to solve the problem of over-decomposition or under-decomposition caused by the improper selection of the number of modes K and penalty factor α in the variational mode decomposition algorithm(VMD),the correlation coefficient and energy evaluation index are proposed to reasonably value these two parameters.The advantages of VMD are verified by comparing with the decomposition results of EMD and EEMD to construct simulation signals.The mathematical model of GGO-SVM fault diagnosis based on VMD and sample entropy is constructed,which lays a foundation for the fault diagnosis experiment of gear reduction box.(4)A set of sinusoidal phase modulation laser interferometry experiment system is built to detect and demodulate the micro vibration of solid surface with different spectral characteristics.Experimental results show that the proposed improved PGC-DCM demodulation algorithm can accurately detect solid surface micro vibration information.In the range of measured micro vibration frequency of 500-3000 Hz,the mean signal noise and distortion ratio of interference signal phase demodulation is33.0956 d B,and the dynamic range is better than 22.75 d B.A sinusoidal phase modulated laser interferometry system was used to detect the fault vibration of planetary gear reduction box.The demodulation algorithm is used to demodulate the fault vibration signals of planetary gear reduction box.The demodulation results show that the frequency spectrum characteristics of vibration signals are consistent with the theoretical analysis,and the maximum deviation of characteristic peak frequency is 1Hz.The mathematical model of GWO-SVM fault diagnosis,which integrates VMD and sample entropy,is used for fault identification and state classification,and the correct rate reaches 99.1667%,which verifies the feasibility of the fault diagnosis model proposed in this paper.Finally,this article designs a gear reduction box fault diagnosis software through mixed programming of C # and MATLAB,achieving the integration of diagnostic functions. |
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