The Numerical Simulation Of Highpower Reducer Based On Earth Pressure Balance Shield

Shield tunneling method is a way which uses the shield machine to excavate tunnel under the ground. When it is working, it is able to prevent soft ground surface collapse or maintain excavation face stability, while, keeping the excavation and lining operations safely, then forming the tunnel once. Today, the economy developed rapidly, more and more construction units first select the shield to replace the inefficient traditional excavation method for tunneling.As one of key components of the shield, reducer is the only function parts to drive the cutter. it connected to one side with the hydraulic motor while connected another side to the spindle drive gear, which is the connection between the hub. Reducer is not only plays the role of transfer movement and power, but also impact of the load bearing in the case of an emergency braking situations, so we are very concerned about its load cases.For the earth pressure balance shield machine, the pressure from the axial and radial can be balanced by pressure diaphragm and the accumulation of soil in the excavation room, while the tangential pressure mainly from the cutter's torque generated by friction. The torque will pass through the spindle gear to the reducer, which will bear a variety of torque impacting. Under the influence of different situations, particularly mutations in the soil and emergency braking situation, the impact is particularly evident, which may cause some parts of the reducer failure , even lead to machine down. In order to avoid those situations at the same time also to adapt shield to various soil, it is necessary to make a calculation about the shield reducer under the actual load conditions. This paper used the same intensity and life under the known reducer's spatial structure size and dynamic load as the constraint, aimed to increase the carrying capacity of shield reducer, made an dynamic optimization about the parameters and structure of the transmission components to improve power transmission density and reliability of shield planetary gear reducer. The traditional design method is an analytical method, which can only make a rough calculation with a simplified way, and can only get local stress, displacement, strength and stiffness. It must increase the safety factor to ensure structural strength and rigidity. While we can quickly, accurately and intuitively get the global stress and strain distribution about the structure by the finite element software. Meanwhile, through the finite element analysis on key parts of the shield reducer, we do a structural optimization for the components that can be optimized .As a result; we can achieve reducer lightweight design but not change the strength and stiffness.Study of this paper is as follows:1) The three planetary gear reducer of the earth pressure balance shield is studied in this paper. We use Design Modeler module of ANSYS-WORKBENCH for its modeling, and do a static simulation analysis. So we obtained the stress distribution and the stress data of dangerous section. On the basis above, we return the geometric model and do an amendment for its dangerous section to improve the carrying capacity of the whole planet frame. Next we discuss the affection of strength and stiffness caused by the five design variables. Then we do a topology optimization on the planet frame through the use of AWE-DesignXplorer module, at last we get its optimum quality (11% less than original quality) which meet the carrying capacity, and optimum quality which meet the known stiffness condition.2) The third gear meshing pair of the earth pressure balance shield is studied. Its accuracy model is built by Pro/E software assisted by CAXA and its meshing condition is simulated by ANSYS-WORKBENCH software. Then we get its value of contact stress and bending stress on the meshing moment, which compared the value obtained by the traditional method. Finally, causes of the differences between two methods are analyzed.3) The box of the earth pressure balance shield is studied. First, we obtain its load by theoretical analysis, second we make a static analysis by use of finite element software ANSYS-WORKBENCH and obtain its maximum stress value, through compared with the maximum stress value and allowable stress, and we conclude the box strength meets the use requirements. On this basis, a further discussion about whether the offset of box axis can impact the meshing pair is made. At last, we do a necessary modal analysis and get its natural frequencies and modes of first eight orders, in order to avoid box resonance at run time.In this paper some useful conclusions are achieved by finite element analysis of key components of the earth pressure balance shield machine, which provide a basis for design of shield machine reducer and have great significance in engineering application.