| China is a country with small oil reserves and insufficient primary energy such as natural gas,but high coal content.The long-term economic and technological development has given coal absolute importance.Heading machine is one of the main coal mining and production equipment in the world’s coal producing countries.Its high efficiency productivity is the focus of the coal industry and researchers."Equal emphasis on mining and excavation,and advance in tunneling".The rapid tunneling of coal mine roadway is the key technical measure to ensure the high and stable production of coal mine.The mining technology and its equipment level directly affect the capacity and safety of coal mine production.Strengthening the development of tunneling machinery has become the rapid development of coal industry production.Therefore,based on the current cutting and rock breaking technology of coal mine tunneling roadway,and based on the improvement of the tunneling hydraulic system,this paper proposes a new method of active vibration assisted rock cutting,and mainly carries out the following research work:(1)Based on the cutting mechanism of coal and rock,the stage of mechanical rock breaking process and the ability of coal and rock to resist external interference are discussed;Based on the traditional rock cutting mechanism and stress wave theory,a new auxiliary cutting mode is proposed: active vibration assisted rock cutting mode;The cutting model of the pick is established from the angle of elastic-plastic fracture,and the pick and cutting head are analyzed,which is the basis for the subsequent research on cutting performance;The vibration and kinematics models of the rotary cutting working condition are studied,and the lateral vibration response frequency of the rotary cutting working condition of the roadheader and the relationship between the swing of the cutting part and the displacement of the hydraulic cylinder are obtained;(2)The excitation system is designed.Based on the alternating fluid flow,the design scheme of the system is described,the working process and characteristics of the rotary valve are explained,and the parameters and structures of the rotary valve and the excitation cylinder are designed;The mathematical models of rotary valve flow process,hydraulic pipeline and vibration cylinder movement process are established to provide the theoretical basis for the system simulation in the following paper;(3)The AMESim software is used to build the simulation model of the system design scheme mentioned above.The accuracy of the simulation system is verified by the pressure change of the two chambers.The system related variables(such as external load type,pump displacement,excitation frequency,pipeline parameters)are changed to study the law of changes in excitation amplitude,velocity,acceleration of the system output,and the dynamic performance of the system based on the autonomous excitation theory is studied;(4)The ANSYS software is used to conduct finite element modal analysis on key components of the excitation system.Through modeling,meshing and solving,the vibration mode diagram of the rotary valve and the corresponding deformation of each order are obtained.It is analyzed whether the key components have resonance phenomenon when the system is working and whether it can work smoothly;(5)The dynamic cutting performance is analyzed by using the edem discrete element software,and the model of the simulated coal wall is established.Based on the statistics of the number of coal and rock particles cut,the spatial distribution of scattered positions,and the particle cutting speed(X,Y,Z direction)and other parameters,the traditional cutting method and the active vibration cutting method are compared,and the impact of vibration excitation on the cutting performance is analyzed.This paper has 59 figures,8 tables and 83 references. |
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