Research On Dynamic Characteristics Of Cutter-Head Driving System In TBM

Full Face Rock Tunnel Boring Machine(TBM)is a large tunnel construction equipment that bears the advanced characteristics of high efficiency,superior quality and safety.The cutter-head system is driven by the main driving system to drive the cutters that are installed on the cutter-head to cut and crush rock.As a key component of TBM,the cutter-head system plays the functions of crushing rock,stabilizing excavated opening and so on.Due to complicated geological conditions,the cutter-head system bears multipoint random impact loads,leading to larger vibration on cutter-head and driving system.And vibration will bring about some malfunctions,such as bolt fracture,seal fatigue of the main bearing and drive shaft failure,which may increase maintenance cost and affect the TBM tunneling efficiency.Therefore,it is necessary to study the dynamic characteristics of the driving system in TBM for reducing failures of the driving system under complex conditions.Based on the project supported by the Collaborative Innovation Center of Major Machine Manufacturing in Liaoning and the summary about research of tunnel boring machine cutter-head system,the nonlinear dynamic model of cutter-head driving system is established.Then,the natural characteristics and dynamic characteristics are analyzed and the effect of different factors,such as rotational speed,load fluctuation and meshing error,are studied on the drive system,respectively.The paper provides a theoretical basis to guide the dynamic design,vibration control and structure optimization design of cutter-head driving system.In this paper,main work is as follows:(1)The nonlinear dynamic model of a gear-rotor-bearing system is presented by analyzing the structure feature of gear system and the model considers the influences of torque,gravity,gear clearance,time-varying mesh stiffness and so on.The dynamic equation is solved by using Runge-Kutta numerical integration method to analyze the dynamic characteristics and the influence of parameters on system.And it will provide the basic method to study the driving system.(2)According to the lumped parameter method,the dynamic model of cutter head driving system is established by analyzing the characteristic of redundant drive mode in the driving system.The model comprehensively considers of the factors,such as meshing error,time-varying meshing stiffness,gear clearance,gravity,torque,and so on.Disc cutters are simulated with the finite element analysis software ABAQUS to gain loads from different directions,which will provide the external excitation for the driving system.The parameters about internal damping and stiffness are analyzed in details.(3)The natural characteristics,natural frequency and vibration mode,are analyzed to obtain the vibration form of the driving system and prevent the resonance.Dynamic equations are solved by using Runge-Kutta numerical integration method and the dynamic response results are validated through comparing engineering data with theoretical values.Then,the influence of various parameters on the dynamic response are explored.The results show that under a certain advance speed,with the decrease of the cutter head speed,the load in cutter increases,leading to increasing system vibration.When the backlash or meshing damping coefficient increases,the vibration amplitude will increase.It is a great significance for avoiding greater vibration to reasonably choose the value about meshing backlash and damping coefficient.Thus these numerical results will provide a reference for dynamic design.(4)The sensitivity of driving system is analyzed by using sensitivity analysis theory.The direct derivation method is used to determine the sensitivity equations of driving system.Based on system dynamic response results,sensitivity is calculated to analyze the influence of stiffness and the results can provide a theoretical basis to dynamic design,vibration control and structure design of the main driving system.