| Taking the 17-layer coal of Yankuang Group as the research coal seam,and taking the MG2×55/250-BWD type coal shearer spiral drum as the engineering object,for the two functions of coal cutting and coal loading of the coal mining machine working mechanism,the dynamic force transfer law of spiral drum cutting coal containing dirt band was studied.Physical and mechanical tests were carried out on the 17-layer coal rock sample,and the parameters of coal and rock were calibrated by the combination of neural network and discrete element method.A model of the coupled drum-coal-dirt band was established by discrete element to study the dynamic force transfer law of the drum.The results show that when the drum cuts the coal containing dirt band,the drum speed increases from 75r/min to 105r/min,and the average value of the total force decreases from 2.78×104N to 2.36×104N,the total force of the drum decreases with the increase of the rotation speed of the drum.The traction speed of the shearer increased from 3m/min to 6m/min,and the average value of the total force on the drum increased from 1.33×104N to 3.41×104N.As the traction speed increases,the average force of the drum increases,and the simulation results of the drum force are consistent with the theoretical analysis.When the pick is inserted into the coal rock,the instantaneous force of the coal rock in the statistical area is 57.34N.The pick gradually cut into the coal wall,and the force of coal is 647.03N.As the drum continues cut the coal,the force of the coal is between 70.48N and 213N.When the pick cut to the coal-rock interface,the impact force of the coal rock is 720.438N,and the maximum force of the pick cutting the rock is 1611.24N.The force of 184.64N for cutting the rock-coal interface is much smaller than the force of 720.438N for cutting the coal-rock interface.The mathematical model of the force and transmission distance of coal rock is established when the drum cuts the coal with dirt band and the law of force transfer is analyzed.The contour map of force and transmission distance was obtained,it is found that when the pick cuts the coal rock,with the increase of the distance from the action point of the pick,the force of coal and rock is attenuated and transmitted outward,which are consistent with the experimental results.Based on the discrete element simulation of drum cutting coal and rock,the loading rate was studied.It can be seen from the research results that the drum speed increases from 75r/min to 105r/min,and the coal loading rate increases from 41.68%to 48.77%;The traction speed of the shearer is increased from 3m/min to 6m/min,the coal loading rate is reduced from 46.47%to 43.35%;The cutting depth is increased from 480mm to 630mm,and the coal loading rate is reduced from 56.90%to 45.59%.The rigid-flexible coupling dynamic model of shearer is built using Pro/e,ANSYS and ADAMS,the two-way coupling method of multi-body dynamics and discrete element was used to study the dynamic force transfer law of spiral drum cutting coal containing dirt band,the results show that the total force,cutting resistance force,and traction resistance force of the drum after coupling have increased,which are 11.64%,12.17%,and 13.33%,respectively,the value of the lateral force has decreased by 20.86%.In the process of cutting,the main destructive force of coal and rock is shear force,with tension and pressure,and the average value of the normal breaking force received when the bond is broken is 30141.88N,and the average value of the tangential breaking force is 42539.71N.The ratio of the average tangential destructive force of each pick to the normal average destructive force is between 1.154?1.564.During the transmission of force in coal and rock,the range and shape of the force change at all times.When the pick cut to the coal-rock interface,the force in the coal rock is the largest.Combined with the coal loading law of the drum and the stress law of the drum,using Creo to realize the parameterized modeling of drum,using the response surface module of workbench to optimize the design and sensitivity analysis of the drum,the results show that when the drum cuts the coal containing dirt band,the length of the pick,the length of the tooth body and the diameter of the tooth body are respectively 165.46mm,76.18mm,and 58.99mm;the angle of the tooth tip,the cone angle of the tooth body,the mounting angle of the pick,and the angle of the helix are 42.088°,50.17°,42.28°,19.76° respectively.The maximum deformation,maximum stress,load fluctuation coefficient and maximum coal loading rate of the drum are 0.2808mm,461.04MPa,0.0041,46.4%.After optimization,the maximum deformation,maximum stress and load fluctuation coefficient of the drum were reduced by 14.47%,14.22%,and 6.82%respectively,and the coal loading rate increased by 10.89%.The sensitivity analysis shows that the installation angle of pick has the greatest influence on the stress and deformation of drum,and the helix angle has the greatest influence on the load fluctuation coefficient and coal loading rate.The paper has 89 pictures,28 tables,and 154 references. |
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