| Coal is an important pillar of national economic development.With year by year mining,the thick coal seams and medium thick coal seams in some mines show depletion phenomenon.The mining of thin coal seams in China is increasingly important because of the abundant mineable reserves.However,due to the complex and diverse conditions of thin coal seams,small mining space,immature technology and unsatisfactory production results,the phenomenon of selective or abandoned mining occurs,resulting in a huge waste of coal resources.Therefore,it is imperative to develop new thin coal seam mining equipment to realize mechanized,unmanned and efficient intelligent mining of thin coal seams,which can help promote industrial development and improve economic level.To this end,this thesis proposes a new type of thin seam coal mining machine suitable for 0.5～1.3m coal seam mining,and conducts research on the structural design of different functional modules of the whole machine,simulation and optimization of cutting performance and transportation performance,and finite element analysis of key components.Based on the requirements of thin seam mining,the structural design of different functional modules of the machine,such as walking mechanism,clamping mechanism,transfer and pushing mechanism,cutting section and spiral transport section,is carried out.The load and cutting performance of the cutting section are analyzed theoretically,and the transport performance of the screw transport section is analyzed to obtain the main factors affecting the cutting performance and transport performance,so as to lay the theoretical foundation for the subsequent simulation study.Finally,according to the design of different functional modules,a three-dimensional model of the new thin coal seam coal mining machine is drawn.According to the theoretical analysis of the cutting performance of the cutting section,LS-DYNA is used to establish the simulation model of coal rock cutting by drum,and the influence of cutting impedance,drum speed and propulsion speed on cutting load is analyzed by the method of control variables.According to the values of the motion parameters under different cutting impedance conditions,the comparison analysis of cutting load and cutting performance is carried out,and it is obtained that the change of motion parameters under different cutting impedance can obtain better comprehensive cutting performance,which provides the basis for adaptive variable speed cutting in the future.Based on the theoretical analysis to determine the range of parameters affecting the transport performance,the biaxial spiral transport section model with different parameter values is established by EDEM discrete element software.The number of helix lines is determined by simulation analysis,and the effects of axis distance,guide length and rotational speed on mass flow rate,transport speed and blade stress are analyzed univariately.By designing orthogonal experiments for multi-factor analysis,the matrix analysis method is used to establish the matrix of index layer,factor layer and level layer to determine the weight matrix and calculate the optimal combination scheme under the comprehensive transport performance evaluation index.The key components of the spiral transport section are subjected to force analysis;the finite element software is used to conduct static analysis on the propulsion plates,pins and tow hooks on both sides of the shell section to verify the safety of the designed structure;the topology of the propulsion plates is optimized to achieve the requirement of light weight,and the strength and stiffness of the reconstructed model are verified to meet the requirements of working conditions.Based on the best combination solution,the static and modal analyses of the biaxial spiral components and their cages were carried out to verify the rationality of the designed structure and the absence of resonance phenomenon during operation.The thesis has 73 figures,15 tables,and 91 references. |
PDF Full Text Request