Research On Mechanical Properties And Looseness Of TBM Cutter Mount System

In the process of rock breaking of tunnel boring machine,the cutter mount system will be subjected to a large impact load.The cutter is fixed on the tool holder by the locking system,and the rock breaking load will be transferred from the cutter to the locking system and then to the tool holder,which makes the locking system produce violent vibration,and often leads to the loosening of the locking system and serious engineering problems such as hob falling.Therefore,it is of great theoretical value and engineering significance to analyze the mechanical properties and dynamic characteristics of the hob locking system,study the loosening reasons of the hob locking system and improve the locking system.In this paper,the static and dynamic performance of the normal hob locking system under the condition of red sandstone and granite is deeply studied.The main work and conclusions are as follows:(1)Based on the full-size linear cutting experimental platform of Central South University,rock type,hob spacing,penetration and other parameters were used as variables to carry out the rock breaking experiment of 17-inch hob.Meanwhile,the acceleration of the cutter shaft in the process of rock breaking was measured to verify the dynamic model.The rock breaking loads with three tool spacing and three penetration degrees under the condition of red sandstone and granite are compared and analyzed to provide load motivation for the statics and dynamic mechanics research of the tool holder system.(2)Based on the static module of Ansys-Workbench,a static finite element model of the cutter mount was established to study the statics characteristics of the cutter holder under the ultimate load.The stress and deformation of each component under different bolt preload and different load are compared and analyzed.(3)Based on Ansys-Workbench transient dynamics module,a dynamic finite element model of the cutter mount system was established,and the dynamic response of each component of the cutter holder system under different rock crushing and bolt pretightening forces was analyzed by using the triaxial acceleration of the cutter shaft measured in rock breaking experiment.The loosening failure reason of hob locking system is studied and the locking system is improved.(4)Based on the similarity theory,a scale-down model of the improved cutter mount system was established and the scale-holder was made.The vertical load was applied to the scale-holder by the highperformance experimental platform of Central South University,and the stress of the cutter holder and bolt was measured.The experimental results verified the correctness of the statics simulation.