Research On The Dynamics And Fault Diagnosis Of The Large Gear Transmission Systems

Under the grant of the key project named"Research on the Large Power Controlled Start/Stop Transmission System"from Jilin province and the project named"Dynamic Simulation and Structural Strength Analysis of FWK-12 Electric Mining Shovel"from Fushun Mineral Industry Group, the research of the paper is focused on the spur gear pair of the large power controlled start/stop transmission and the helical gear transmission system of the electric shovel crawler traveling system for the study of the gear dynamics simulation and fault diagnosis.Based on the study of the time-varying meshing stiffness of the gear pair, the dynamic simulation models of the large spur gear pair and helical gearing system are built up. The study on diagnosis for malfunction types of cracked tooth and broken tooth is performed by utilizing the wavelet analysis techniques on the basis of dynamic simulation of the gear transmission systems. The dynamic properties of the large gearing systems at the start-up and brake-down working conditions are obtained through the simulation. Meanwhile, the effects of cracked tooth on the meshing stiffness are also studied through the simulation. The experimental study on the intelligent control of the large power controlled start/stop transmission system is also carried out on the test bench.The first chapter is introduction, in which evolution history and the state of art of the gearing systems dynamics and their fault diagnosis is summarized and categorized into several major research directions: (1) the research on the parameters of the gear dynamics, including gearbox dynamics, gearing contact forces and meshing stiffness;(2) the research on the abstraction of gear faults features, involving the identification of the crack and wearing of the gear teeth;(3) the research on the analysis and processing of the vibration and noise signals of the gearbox. The contents and means are presented for the research in this paper based on the above summary.The second chapter involves the research on the large gearing dynamics models. The idea and methodology for the computing of the time-varying meshing stiffness, an important parameter of the gear dynamics model, are presented. The core of the methodology is to take a gear tooth as a variable cross section beam and establish the deflection differential equations which are able to be solved by numerical method, considering the tooth bending deflection, axial compression deflection, shearing deflection, deflection caused by flexural gear base and gear contact deflection. The compliance function of the angle between meshing force acted on the tooth surface and the centerline of the gear tooth is derived according to the involute gearing geometry, and the algorithm for programming is presented. A set of gear motion differential equations with 36 DOF for the electric mining shovel travelling gearbox are formis performed in FEA software ANSYS. It is concluded that the flexural base deformation and contact deformdynamic model of the large spur gear pair is formulated, and the start-up and steady operation modes are adopted for the dynamic simulation to get response of the angular ipment in the large powemesh cycle by means of wavelet analysis is presented for the precise gear fault identification. The feasibility of the methodology is validated through the wavelet analysis of the simucracked beam into the cracked tooth which is considered as a cracked variable cross section eam, the relationship between the depth and location with the meshing stiffness on therformed to form the theoretical foundation of the precise gear crack identification method. The three stage helical gearing dynamics model for the electric mining shovel travelling gearbox is established and the ed, considering the gear teeth, shafts and bearings as the elastic elements, and the parametric calculation method for the elastic elements bearings is presented.The third chapter is for the numerical simulation of the meshing stiffness of the gear pair. An algorithm for the deflection and stiffness of single tooth is presented and programmed in MATLAB on the basis of single tooth deflection analysis in the second chapter. The numerical simulation for above mentioned 5 types of deflections is performed the deflection diagrams are plotted. The detailed error analysis for the deflection computing is performed in FEA software ANSYS. It is concluded that the flexural base deformation and contact deformation algorithm in current use are not suitable for the large gear calculation because of the dramatic error. The algorithm for gear tooth deflection is modified according to the FEA method and precise single tooth meshing stiffness for the large gear pair is obtained. A meshing cycle algorithm for the single-double meshing model is presented based on the meshing cycle analysis, and the time-varying equivalent meshing model and meshing stiffness are obtained by using equivalent stiffness method.The fourth chapter is for the large spur gear pair dynamic simulation. The 2-DOF dynamic model of the large spur gear pair is formulated, and the start-up and steady operation modes are adopted for the dynamic simulation to get response of the angular velocity of the gear when not considering the gear transmission errors. On the other hand, the angular velocities of the gear response under the above mentioned conditions are simulated separately. The demand for the soft start or controlled start equipment in the large power driving systems is stated according to the simulation results.The fifth chapter is about the gearing faults detection based on the wavelet analysis, in which the fault detection mechanism for gearing transmission is stated. A methodology to detect the angular velocity response singularity caused by the meshing stiffness variation in a mesh cycle by means of wavelet analysis is presented for the precise gear fault identification. The feasibility of the methodology is validated through the wavelet analysis of the simulation data at different working conditions. By introducing the elastic joint model of cracked beam into the cracked tooth which is considered as a cracked variable cross section cantilever beam, the relationship between the depth and location with the meshing stiffness on the gear tooth is studied and the numerical simulation is performed to form the theoreticalfoundation of the precise gear crack identification method. The three stage helical gearing dynamics model for the electric mining shovel travelling gearbox is established and the nonlinear contact simulation is performed by MSC. ADAMS, which is a commercial multi-body dynamic simulation software. Post processing of loading is then accomplished using the MATLAB Wavelet toolbox. The method allows for nonlinear contact mechanics to include the effects of friction, damping, and hertzian-contact in a localized region of gear mesh. Simulation results show that this method can predict the fault pattern of the gearbox. Wavelet analysis is shown to have good resolution in the time and frequency domain and it is effective to obtain the cyclic features of the gearbox fault signals.The sixth chapter is about the experimental study of the intelligent control of the large power controlled start/stop transmission system. The dynamics model of the large power controlled start transmission is built up and its working process is analyzed. The fuzzy control and adaptive fuzzy neural control models are built up and the computer simulation and experimental studies are carried out. The simulation results showed that the control algorithm can modify the fuzzy control parameters to adapt the load variation by training the neural network. The experimental study on a test rig validates the simulation results.The seventh chapter is a summary of the whole dissertation. The creative research results and conclusions are presented based on the abstraction of the whole dissertation.