Reliability Evaluation And Optimization Design Of Gear Transmission System For Earth Pressure Balance Shield Reducer Based On Dynamic

With the rapid development of national economy and urban construction, the exploitation and utilization of underground space has becoming more and more urgent. As a fast, safe, effective, and highly degree of automation tunnel boring machine, shield has been widely used. The shield reducer is the key equipment of shield cutter driving system. Because of its special working condition, small vibration, noise, and high reliability were required for the reducer. Accordingly, carrying out the research of dynamic characteristic and reliability assessment based on the dynamic of the reducer under variable conditions is help to improve the performance of shield reducer. Thus further speed up the localization process of the shield reducer.The thesis subject is supported by project Earth Pressure Balance Shield Reducer which is part of key technology of TBM belongs to the national 863 advanced manufacturing field. Regarding the gear transmission system ofφ6.3m EPB shield reducer as object, research the dynamic characteristic of the gear transmission and analysis the reliability of gear transmission based on varying external load and internal incentive. This provides a scientific and rational method and theoretical support for the localization of the EPB shield reducer.Concrete research work as follows:A pure torsional dynamic model is built by using lumped-parameter method, in which time-varying meshing stiffness, meshing damping and transmission error are included. According to behavior of EPB shield reducer transmission system, the external load, meshing stiffness, meshing dumping and transmission error were analyzed.The natural frequencies and corresponding mode shapes of the transmission system are calculated. The dynamic characteristics of the system were analyzed too. Then the dynamic responses of the transmission system such as vibration displacement and meshing force of each pair under varying internal and external excitations of gear are investigated. The relationship between the external load and the dynamic responses was analyzed.The expressions of the use coefficient and dynamic load coefficient under varying load are provided. The curve of the use coefficient and dynamic load coefficient are got by dynamic analysis. The variation of the use coefficient and dynamic load coefficient were analyzed. It offers an rational and science method for the value of load coefficient.After completed failure modes of the system, the reliability assessment model of the system based on dynamic is set up with considering the varying load. The reliability of the self-supporting design and manufactureφ6.3m EPB shield reducer was calculated.A parameter optimization design model was established for the planetary gear transmission system based on dynamic and reliability. According to the weak reliability of the third stage gear system, an optimal design for the third stage gear system with the highest reliability as objective function was carried out. The optimized design parameter can significantly improve the third stage gear system.The research work of this paper has provided some theoretical references for the engineering design of the EPB shield reducer under varying load conditions, and laid the foundation for the industry application.