Research On Gear Failure Mechanism And Diagnosis Method Of Transmission System Of Converter Tilting Device

As an important equipment in iron and steel production,shaft-mounted tilting mechanism of converter is prone to failure and loss due to its working characteristics and environment.At present,the concentrated mass model is mostly used to study the torsional characteristics of shaft-mounted tilting mechanism of converter,while the bending torsional coupling effect caused by the transverse elasticity of the system is ignored;In addition,under the environment of ultra-low speed and heavy load operation,the dynamic mechanism and diagnosis method of system gear fault need to be deeply studied.Therefore,considering the structural characteristics and vulnerable parts of shaftmounted tilting mechanism of converter,the bending torsion coupling dynamic model of the four in one multi-point meshing gear system of the converter tilting device is established,and its motion differential equation is established based on the Lagrange equation method.Considering the time-varying stiffness characteristics caused by gear failure,the dynamic model of tilting device with gear failure is established;Then,the Newmark-β method is used to analyze the vibration response of the system under normal and fault conditions(gear broken teeth,cracks,wear),and the gear failure mechanism is revealed;A signal analysis method is proposed for the qualitative diagnosis of gear crack faults.The specific research contents of this paper are as follows:(1)The structural characteristics of converter tilting device are analyzed.Aiming at its gear transmission system,the bending torsion coupling dynamic model of four in one multi-point meshing gear system of converter tilting device is established by using the centralized mass method.(2)The meshing stiffness of normal gear is calculated based on the energy method,and then the accuracy of the energy method is verified by Hyper Mesh combined with workbench quasi-static algorithm.Finally,aiming at three common gear faults(broken tooth,crack and wear),the energy method stiffness calculation model is established,and the gear meshing stiffness under several fault states is calculated.(3)According to the established four-in-one multi-point meshing gear system bending-torsional coupling dynamics model,the Newmark-β method is used to calculate the vibration response of the system under normal conditions;At the same time,the workbench is used to establish the finite element simulation model of the four in one gear transmission system of the main body of the tilting device,and the correctness of the centralized mass model is analyzed and verified;Then,the fault time-varying meshing stiffness is embedded,the dynamic model of the system with fault(gear broken,crack and wear)is established,the dynamic response of the fault system is calculated,and the gear fault dynamic mechanism of the tilting mechanism is studied.(4)Aiming at the qualitative diagnosis of driving pinion crack failure,an improved multi-point optimal minimum entropy deconvolution adjusted(MOMEDA)combined with envelope spectrum method is proposed in this paper.Wavelet packet denoising is used as the pre-processing method of fault signal,and the proportion of fault envelope energy is proposed as the quantitative index.Gaussian white noise is added to the theoretical crack dynamic response to simulate the interference of actual background noise.The research shows that the simple MOMEDA method can’t find the fault characteristic frequency,but the improved MOMEDA envelope spectrum method can successfully find the fault sideband,which shows the effectiveness of the method proposed in this paper.