Dynamic Characteristics And Impact Performance Of The Impact System Of A Dual-Chamber-Controlled Hydraulic Drifter

Hydraulic drifter,as a rotary impact drilling equipment,is widely used in engineering operations,such as mining,tunneling,and urban construction,because of its economy,flexibility,and wide adaptability.As the operation project continues to develop in the direction of maximization and scale,a hydraulic drifter must have the characteristics of high frequency,high power,and high efficiency.A dual-chamber-controlled hydraulic drifter is in line with this development direction due to the structural characteristics of double-sided oil return and energy transfer.The effects of design parameters and internal flow on the impact performance(impact energy,frequency,efficiency)and stress transfer law of piston impact drill rod are investigated to explore the primary vibration stability of the impact system of the dual-chamber-controlled hydraulic drifter during impact period.The mathematical and Simulink simulation models of the impact system,Fluent simulation model of internal flow,mathematical and LS-DYNA simulation models of impact process are established in this study,aiming at the impact movement and impact stress transmission processes of the impact system.Dynamic characteristics and impact performance of the dual-chamber-controlled hydraulic drifter under different system design parameters are analyzed combined with experimental test.This research has a guiding significance for developing a hydraulic impact drilling technology.The main research results are as follows:(1)A linear model of the hydraulic drifter impact system is established aiming at one or more vibration phenomena in the impact period of the feedback dual-chamber-controlled hydraulic drifter impact system.On the basis of the linear system state-space description theory and method,the existence range of piston primary vibration in one impact period is determined,starting with the velocity recovery coefficient R,acceleration ratio KF,and acceleration switching time Kt.This approach provides a theoretical basis for designing the position of the piston signal feedback port of the impact system.(2)The nonlinear mathematical and Simulink simulation models of the dual-chamber-controlled hydraulic drifter impact system are established considering viscous frictional resistance,sealing resistance,hydraulic sticking force,steady flow force,and transient flow force.The effects of impact system parameters on the impact piston motion characteristics are analyzed on the basis of control variables,such as piston mass,input flow,supply pressure and the working areas of the front and rear chambers.The impact energy,frequency,and efficiency trends of the impact system are revealed when system parameters change.The results show that there is a high-efficiency area in the design of the system parameters of the dual-chamber-controlled hydraulic drifter.(3)The internal leakage and hydraulic sticking model of impact piston,flow force simulation model of high-frequency reversing valve are established to clarify the influence of transient flow field in the impact system on the movement process of the piston and reversing valve.The optimum scheme of the piston pressure equalizing groove distribution and structure of high-frequency reversing valve suitable for the dual-chamber-controlled hydraulic drifter is proposed.This scheme solves the problems of piston clamping and ensures the reliability of the high-speed reversing of the reversing valve.(4)On the basis of the impact motion of the dual-chamber-controlled hydraulic drifter,the LS-DYNA impact model of an impact system piston-drill rod is developed to explore the internal stress transfer characteristics during impact drilling.By changing the impact speed of the piston,the length of the drill rod,and the contact area of the piston-drill rod,the influence of the matching parameters on the stress spectrum is analyzed when the piston-drill rod collides.The stress wave transmission law in the drill rod and the impact performance change trend of the system under different parameters are obtained.Furthermore,the energy transfer process of the impact system of the dual-chamber-controlled hydraulic drifter is expounded.(5)On the basis of these research results,the impact system of the dual-chamber-controlled hydraulic drifter,with a working pressure of 18-25 MPa and workflow of 60-100 L/min,and two pistons with different lengths were developed.The stress wave method is used to test and analyze the stress wave,impact energy,impact frequency,impact power,and impact efficiency of the long and short pistons of the hydraulic drifter under different impact pressures and gear positions.The experimental data of selecting an impact piston under the hydraulic drifter impact system are obtained,thereby providing a reference for the design and test method of dual-chamber-controlled hydraulic drifter.