The Fea And Lifetime Research Of Main Bearing Used For Tunnel Shield Machine

Shield machines are the main machines in the tunnel construction. Therefore, they must have high reliability, and can work stably. The main bearing of TBM is the key component which always adopts three-row roller slew bearing. The construction and load circumstance of the main bearing are complex. This condition will result in large distortion and stress, and affects the safety of tunnel shield. Because the three-row roller bear is large in size and has many rollers, this makes the contact parts between ring and roller many and the contact status complex. Therefore, it is complicated for both theoretical calculation method and finite element method to calculate the bearing capacity, the deformation and the load distribution.This paper employs theory calculation method and finite method to study the carrying capacity, distortion and loads distribution of the main tunnel bear. Firstly, it analyzes force status of bearing's three rows roller under static load, calculates the load distribution of the three rows roller under axial force, radial force and moment with the calculation method of the load distribution in rolling bearing, and eventually obtains the largest contact stress and distortion values of each roller under loading and identifies the position of the largest load roller. Then it adopts ANSYS to analyze stress and distortion of the bearing under axial, radial force, overthrow moment and combined loads. The results of finite element analysis of load distribution trend, stress and distortion are close to results of roller bearing theory analysis.The main shield bearing is characterized by low speed and heavy load and its general damage form is fatigue fracture. On the basis of the analysis of the mechanical properties of the bearings, the fatigue life of bearing is calculated with the help of classical bearing fatigue life analysis theory and fatigue life analysis method, combining the actual structure. The analysis results demonstrate that the fatigue life of bearing meets the expected service life. The experimental results of mechanical properties and the theoretical analysis results of the main shield bearing have very good consistency in changing trend under many load conditions.The studies on the force status and fatigue life, as well as the carrying capacity experiment of the main bearing of TBM, provide a basis for selection and optimization design of the main bearing of tunnel shields.