Research On Rock Breaking Characteristics Of Roadheader Self-control Water Pick

The roadheader is the key equipment to coal mining, which performance directly affects drivage efficiency. During the excavation of hard rock, the roadheader picks are subjected to low cutting efficiency, serious wear and high temperature. Combined rock breaking with high pressure water jet and pick can solve the problems above effectively.Based on the fluid dynamics theory, a new roadheader self-control water pick, which can control the flow automatically, is put forward in this thesis. As a result, wastes of water and inundation problems are solved effectively, which exist in the normal method of combined rock breaking with high pressure water jet and pick. The theoretical analysis,simulation and test are combined to investigate working performance and rock breaking characteristics of self-control water pick.Based on mechanical rock breaking theory and water jet rock breaking theory,combined rock breaking theory with high pressure water jet and pick is studied in this thesis, to seek rock crack propagation law. Through analyzing the working principle of self-control water pick, mechanical structure and inner channel is designed.Flow field simulation models of self-control water pick are established by FLUENT software, which include flow field under unload condition, flow field of nozzle under free jet and flow field of water jet impacting rock. Reduction of flow characteristics, flow field distribution of unsubmerged jet and influence law on impacting rock flow field characteristics by dimensionless target distance are studied, which can provide the basis for structure design and parameters selection of self-control water pick.Friction resistance characteristics and fluid dynamics force of self-control water pick are analyzed, based on which dynamic response model of pick is established. Response patterns in opening and closing process of self-control water pick are seekd, to prove the feasibility and reliability of self-control water pick. Furthermore, the effect of rock tensile strength, cutting depth, water jet pressure and structure parameters of pick on dynamic response characteristics is studied.Rock breaking characteristics simulation research of normal pick and self-control water pick is conducted by LSDYNA software with FEM-SPH coupling algorithm. The effect of rock tensile strength, cutting depth and water jet pressure on rock breaking efficiency is studied systematically. Mechanical characteristics simulation research of self-control water pick is conducted by Workbench software. The effect of rock tensile strength and cutting depth on stress and deformation distribution of self-control water pickis studied, and structure optimization scheme of the pick is put forward.Rock breaking test bench for self-control water pick and rock sample are developed.Furthermore, self-control water pick system is designed and processed. Test research on self-control water pick is conducted, which include friction resistance characteristics test in closing process, opening characteristics test, dynamic response characteristics test, flow characteristics test and rock breaking characteristics test. Influence factors and rules are analyzed to provide the basis for practical application of self-control water pick. Test results and simulation conclusions are basically identical, which indicate the simulation models are correct.