Study On Cutter Force Real-Time Monitoring System And Method For TBM

Cutting forces is one of the most important parameters in the excavation of tunnel boring machine(TBM),which can judge the operating state of the machine.But the real-time monitoring of cutting forces is difficult due to the construction environment.In this paper,the study on cutter force real-time monitoring system and method is carried out based on the disc cutter assembly manufactured by China railway engineering equipment group co.ltd.The main research work and progress are as follows:(1)The rock breaking mechanism and load condition of disc cutter are analyzed first,then choose the most reasonable sensor installation location in the load transfer path of the cutter system.Next,a method based on the vibration theory for force measurement is proposed considering the fluctuation characteristics of the actual load.Cylindrical strain gauge can be embedded into the cushion block and acquire its deformation,then the real-time monitoring of cutting forces can be realized through the wireless strain sensor,wireless gateway and the data acquisition and control software.(2)According to the structure of cutter assembly,the system is discreted into several parts and dynamical model of the disc cutter system coupling bending-swing is established by concentrated mass method.Then the differential equations can be acquired using Newton's second law.Through the theoretical formula,numerical simulation and existing research results,we can determine the kinetic parameters of structure and interface in the model.The vibration model provides the theoretical basis for the cutter loading identification.(3)The load transfer law of the cutter system is analyzed.Random vertical force and lateral force are as the excitation for system to conduct the vibration response analysis and the force of the cushion block can be calculated.The result shows that:the vertical force and lateral force calculated by static equilibrium theory are larger compared with input excitation load,the vertical force significantly larger especially.The vibration of the cutter system has an amplification effect on the load transfer in certain range,so vibration factor must be considered in the force monitoring.(4)The accuracy of load identification by vibration model is an important aspect.First,the identification error is quantitated and error estimate formula is established.Then load is identified by vibration response with 0,5%and 10%noise,the result shows that identification load has a deviation compared with actual load,but it is very small and they have the same trend.The method has fairly strong antinoise ability,which can satisfy the requirement of engineering application.(5)The cutter force monitoring method is verified by laboratory experiment.In rotary rock breaking experiment,the load of cushion block is acquired and the vertical force and lateral force of cutter is obtained by vibration equations,which increase with the increase of the penetration.The vertical load is different from the oil cylinder load,but their trend is nearly the same.The result shows the feasibility and effectiveness of the force monitoring method,and shows the reliability of the lateral force calculated indirectly.