Study On The Lateral-torsional Coupling And Uneven Loading Of Rotating System In Shield Machines

Shield machine is a kind of technology-intensive equipment used widely in the tunneling construction, which is capable of excavation, supporting, thrusting, lining and other operations functions. It has been playing an increasingly important role in the country's infrastructure construction. Generally, the rotating system of shield machine is used to cut the soil. And the cutterhead is usually driven by a redundant actuating system with many motors. Although the mode of redundant drive can provide an extremely driving torque, the unexceptional internal forces tend to be generated due to the motion error, which will result in uneven loading among the motors. It is likely to bring on the incidents such as the rupture of shaft and the blocking stop of cutterhead. Therefore, it is significant that the transferring behavior of the load is investigated due to the overall design, control and accident prevention on shield tunneling.The study on the stiffness of large-scale slewing bearing for the rotating system in a certain type of shield machine subjected to the bending moment and radial force is conducted. Then, the calculating model of stiffness of internal gear is established in terms of Weber energy method considering the time-varying mesh synthesis stiffness of gear pair. Based on the two studies above, a lateral-torsional coupling method is employed to solve the additional meshing force of gear-bearing-rotor system generated by displacement disturbance. Further, the numerical simulation on rotating system in this shield machine under the typical operating conditions is done. The analysis and evaluation on its uneven loading generated by lateral-torsional coupling effect is also compared. It can provide the theoretical basis on the optimal design of structures and control strategies of the rotating system in shield machines. The details can be summarized as follows.1. The finite element model on the three-row roller slewing bearing in the rotating system of shield machine is established. The contact deformation between each roller and raceway is converted into the overall displacement of the geometric center of the inner ring through an equivalent method. The deformation behavior is analyzed subjected to the radial load, axial load and the capsizing moment, respectively. The corresponding stiffness is computed, which is useful in the study of the displacement disturbance.2. An internal gear stiffness calculation model is established based on Weber energy method and the formula of single-tooth-pair stiffness is given. According to this equation, the single-tooth-pair stiffness of this shield machine is calculated. In terms of the sudden change of mesh stiffness generated taking into consideration of the alternation of single and double tooth pair mesh stage. A function is given to describe the influence of mesh stiffness in which the change on contact ratio is taken.3. In terms of the redundant actuating behaviors of rotating system of the shield machine and the stiffness of the slewing bearing, the correlation between the gear transmission and the bearing deformation is investigated. The dynamic model on the gear system with two parallel shaft rotors is established. The lateral-torsional coupling effect subjected to the radial force and the capsizing moment is analyzed. An approach to use the additional meshing force (moment) to describe the influence of gear disturbance on the transmission characteristics is proposed. The correlation between the additional meshing force and the time-varying mesh stiffness is obtained.4. The numerical simulating model of a certain type of shield machine was established in terms of the real structure and actual working conditions, in which the lateral-torsional coupling effect is considered. The addition meshing force generated by moments and radial forces is solved, which is used to describe the uneven loading effect of the multi-motor drive system. The comparison and evaluation between two kinds of distributions scheme of the pinions are conducted taking into account or the uneven loading aspects. It may provide the guidance on the anti-uneven-loading design of rotating system in shield machines.