| Full face tunnel boring machine (TBM) is a kind of large and advanced engineering equipment,which tunnels with cutters.And it is a benchmark to measure the development of the national equipment manufacturing industry.As a key working component of TBM,the cutterhead system is used to break rock and support tunnel face in the excavation process.Once the components fail in the tunnels,it may prolong the construction period,even scrap the whole tunnel.The flange,which is an improtant part of the cutterhead system,transmits the input torque for cutterhead.The reliability of bolts connection on the flange of TBM cutterhead has an important influence on the efficiency of the whole equipment.At present, there is no effective way to the frequent fracture of bolts, which will caused owntime so that seriously affect the efficiency of the construction.In view of the frequent fracture of bolts, there is no detailed and specific research work.Therefore, in this paper,based on the fracture problem of bolts on the flange,a lot of researches are carried out, including the load transmission of cutter load, structure of bolts connectionand loading process of bolt pre-tightening force.The specific work and main thesis of the paper are as follows:(1) Firstly, considering the complexity of cutterhead structure, through the existing calculation formula, the external load of cutterhead is subjected to during the driving process is concluded, which is as an input conditions of simulate. And then axial load and torque at the flange of the cutterhead are obtained.The accuracy of the simulation results is verified by engineering measurement, the results show that the theoretical safety factor of the flange is enough,so load at flange is not the main factor of bolt fracture.(2) Secondly, with theoretical calculation and simulation analysis of Abaqus software, load distribution in the connection structure of the standard screw thread tooth and the stress of each screw thread tooth are obtained, which indicate the disadvantages of this structure, and show that the connection structure needs to be improved. Then the fatigue experiment on double-end stud of standard screw thread connection structure is carried out. And the accuracy of theoretical calculation and simulation analysis are verified by the fatigue fracture of a set of experimental samples.(3) Thirdly, on the basis of theoretical analysis, the taper screw thread structure is proposed to improve the structure of screw thread connection. Then through the simulation and analysis of screw thread connection structure with different tapers, it's known that the best structure is internal screw thread tooth whose taper is 1:400.After getting the most suitable structure, the simulation analysis is carried out under different loading conditions, which shows that the optimum application load of the structure is 245kN?408kN.(4) Finally,aiming at pre-tightening process of bolts on disc flange, the advantages and disadvantages of star assembly pattern and divisiory assembly pattern are analyzed and compared through the experiment on the reduced scale experimental prototype of TBM cutterhead flange plate.Pointed out the applicability of this two pre-tightening technology according to different applications. |
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