| Due to the narrow working space and complex geological structure of Shearer in thin coal seam,there are great abrupt changes in the physical and mechanical properties of hard concretions and coal in homogeneous coal and rock,it leads to a series of problems,such as severe impact of drum load,failure or break of pick,increase of energy consumption of cutting ratio and low loading efficiency.This is related not only to the complexity of geological conditions,but also to the matching of kinematic parameters and cutting position.Based on the cutting part of the shearer MG2×55/250-BWD in service in the target mining area,the 3D mechanical models of Shearer drum,rocker arm and coal wall were established by UG,in the EDEM,the coal-hard concretion bonding model is established by layering and then bonding particles,and the discrete element model of the the coal containing hard concretion is completed.The kinematics parameters of the drum and pick are set up,and the pick of the end plate of the spiral drum is simulated by discrete element method.Based on the coal breaking theory,the load program of Shearer cutting the coal containing hard concretion is compiled,and the simulation load data are compared with the force and moment calculated by the load program of MATLAB,the maximum error rates were 2.46%and 2.59%respectively.Based on the similarity theory,a single-tooth cutting test-bed is built,and the maximum error rate between the simulated load data and the experimental data is 6.81%≤7%.The accuracy of EDEM simulation is verified by both theory and experiment.Based on the method of combining the discrete element method with the finite element method,the EDEM model and the post-processing load data are imported into the Workbench platform through the EDEM Add-In for Workbench interface,the static analysis is carried out,and the stress distribution cloud diagram of the drum and the pick is obtained.Taking drum hub 1-3 section,2-4 section,3-5 section,4-6 section and 5-7 section as examples,the uniform design method is adopted to establish 13 typical working conditions by comprehensively considering the traction speed and drum speed,the construction method of BP neural network is studied,the simulation data is expanded,and a high-precision neural network with a prediction error of 5.57%is obtained.Analyze the influence rule of different hard concretion action position,traction speed and rotating speed on coal loading rate,peak load,energy consumption of cutting ratio,peak stress and load fluctuation coefficient,and obtain the mathematical model and fitting formula of coal loading rate,peak load,energy consumption of cutting ratio,peak stress and load fluctuation coefficient by surface fitting of data through Matlab.The function evaluation method is used to establish the optimization function with the traction speed,rotating speed and hard concretion position as design variables,and the coal loading rate,peak load,energy consumption of cutting ratio,peak stress and load fluctuation coefficient as objectives.The results of the objective function are optimized through particle swarm optimization algorithm.The results show that when the hard concretion is located at the cutting line position of drum 1-3,the drum speed is 71.3r/min,and the traction speed is3.58m/min,the drum reaches the optimal cutting,and the coal loading rate is 35.287%at this time;The peak load of shearer drum is 112.4k N;The specific energy consumption of cutting is1.377k W·h/m~3,the load fluctuation coefficient is 1.0135,and the peak stress is 1296.704MPa.This method can improve the comprehensive performance of the drum by adjusting the kinematics parameters and cutting position parameters of the shearer,it provides a new method and means to reduce energy consumption,load fluctuation,stress,improve drum performance and coal loading effect,at the same time,it also lays a theoretical foundation for the research of intelligent mining control strategy of hard concretion coal seam.There are 70 figures,14 tables and 77 references in this paper. |
PDF Full Text Request