Study On Coal-loading Performance Of Thin Coal Seam Shearer

As the main working part of mining mechanization equipment used in thin coal seamface, the drum performance affects the production efficiency of thin coal seam shearerdirectly. With double motor parallel technology of thin coal seam shearer being maturing,the demand of production has been satisfied by the cutting performance of coal seamshearer drum basically. While the poor drum coal-loading performance has become the keyissue of improving the efficiency of thin coal seam mining and popularization of thin coalseam shearer. Therefore, the research on coal-loading performance of thin coal seamshearer drum has great significance for the development of coal mechanization miningtechnology. In this paper, the methods of theoretical analysis, modelling experiment andsimulation by discrete element software are used. The main structural parameters, workingparameters, coal seam working face angles, position parameters of drum and ranging armthicknesses which affecting coal-loading performance of drum were studied deeply.The coal-loading with drum ejection mechanism and coal-loading with drum pushingmechanism have been analyzed based on theories of mechanics of granular media andmonomer mechanics. Then the computational formulas of axial velocity and tangentialvelocity of coal body with different structural parameters are obtained. Combining thincoal seam shearer drum structure and working characteristics, the influences of drumstructure parameters and working parameters on coal-loading performance of drum areanalyzed. The formulas of the minimum theoretical speed, the maximum theoreticalcutting depth, the highest theoretical speed and circular coal coefficient are given,providing references for the structural design and working parameters selection of drum.Based on the coal rock cutting test-bed, the single factor experiment and three factorsorthogonal modeling experiment about drum structure and working parameters whichimpacted coal-loading performance directly are carried out by using the designed modeldrum. The influence law of drum hub diameter, vane helix angle and drum cutting depth,drum rotating speed, drum hauling speed and the distribution of broken coal particle sizeon coal-loading rates of drum ejection and drum pushing are obtained in single factorexperiment research. In three factors orthogonal experimental research, the significantinfluences of structural and working parameters on drum coal-loading rate are acquired,under the matching of drum hub diameter, vane helix angle and drum cutting depth, drumrotating speed and hauling speed. Modeling test results provide references for the structuraldesign and parameter selection of thin coal seam shearer drum, and provide experimental verification for the subsequent simulation experiment research.Based on the basic theory of discrete element, simulation model of drum coal-loadingprocess is established by using simulation software of PFC3D. Then the influence laws ofparticle parameters and wall parameters on drum coal-loading performance are studied.Based on the condition of modeling test, the accuracy verification model of drum discreteelement simulation is established, and several simulation tests are carried out by using theverification model. The comparison of simulation test results and modeling test resultsshows that the simulation and test results are relatively close with the suitable particlediameter and particle stiffness, which proves that the applying of three-dimensionaldiscrete element method in simulating the coal-loading process is feasibility and accuracy.The drum coal-loading processes with different face angles are simulation studied byusing three-dimensional discrete element software of PFC3D, and then the influence laws ofdip angle in mining direction and dip angle in faceline direction on the coal-loading ratesof drum ejection and drum pushing are obtained. The simulation results show thatcoal-loading rates of drum ejection and drum pushing in the negative dip angle in miningdirection are extremely low, which means that the mechanized mining technology designof the thin seam coal should avoid the negative dip angle in mining direction. Coal-loadingrate with drum pushing decreases linearly with the dip angle in faceline direction. Whilecoal-loading rate with drum ejection decreases observably firstly and then decreases slowlywith the increase of dip angle in faceline direction. Meanwhile, coal-loading rate withdrum ejection in negative dip angle in faceline direction decreases weaker than thehorizontal angle. The improvement measure on coal-loading with drum ejection undernegative dip angle in faceline direction is analyzed and verified in simulation. It points outthat the increase of particle axial velocity and reduction of the particle export positionheight can increase drum coal-loading rate with drum ejection in a certain extent.According to the structure characteristic and working environment of the thin coalseam shearer drum, the simulation model of thin coal seam shearer cutting process isestablished, and the influences of height from drum bottom to scraper conveyor chute,distance from the coal wall to the scraper conveyor chute and the ranging arm thickness onthe drum coal-loading performance are obtained, which provides references for the designof thin coal seam shearer ranging arm, drum and the corollary equipment and workingparameters selection.