Design Of Coal Breaking Experimental System Combined With High Pressure Water Presplitting And Picks And Research On Crushing Performance

Coal plays a leading role in the field of energy and mineral resources in China.Aiming at the problem of low mining efficiency caused by the traditional cutting method in hard and difficult coal seams,the development of coal production industry has been restricted.With the continuous mining of high-quality coal rakes with large reserves in China in recent years,the proportion of hard coal beds is rising,and the overall mining difficulty of coal is also increasing.Seeking a method with universal applicability to improve the mining productiveness of hard coal seam has become an important way to promote the realization of intelligent coal mine.In view of the characteristics of hard coal seam,such as high strength,dense structure and undeveloped fracture,based on the interdisciplinary of mechanical design and mining engineering,this paper proposes a method of pre splitting coal by high-pressure water by comprehensively using the research methods of theoretical analysis and calculation,numerical simulation and field test,establishes the theoretical model of coal cracking and pre splitting,and analyzes the coal quality after pre splitting.In view of the theoretical study,a high-pressure water presplitting experimental system was designed,and the coal wall high-pressure water presplitting cutting operation experiment was carried out,and the coal crushing performance evaluation system was constructed.The main results are as follows.Based on the theory of finite element analysis,the mechanical model of coal wall cracking is established,and the resultant force of coal wall cracking under high pressure water injection of direct hole and inclined hole is obtained.Taking the through mechanical pattern constructed by Mohr stress circle theory as reference,the process of coal wall crack formation,unloading and presplitting is analyzed,and the stress in the cutting process of drum pick is analyzed The mathematical model of specific energy consumption of drum cutting was established based on the factors influencing cutting resistance.The test of coal wall drilling and water injection was simulated by ABAQUS finite element static analysis method.The model of coal wall specimen under three different drilling methods was established,and the influence of high-pressure water injection on the presplitting characteristics of coal wall under different drilling methods was analyzed.The simulation results show that under the same parameters,the peak value of equivalent stress,strain and spatial displacement of crooked hole pre splitting is larger than that of straight hole pre splitting.Considering the functional requirements of high-pressure water presplitting and sheaper combined coal breaking experimental system,the overall scheme of mechanism and test system design is put forward.The cutting platform mechanism is devised to complete the cutting function,traction function,propulsion function and limit function of the cutting platform;the auxiliary presplitting mechanism is designed to meet the high-pressure water injection function,confining pressure and top pressure loading function of the auxiliary presplitting mechanism;the auxiliary presplitting mechanism is planned The data acquisition system realizes the acquisition of infrared thermal image signal,acoustic emission signal,cutting parameters and crushing process image data signal.Based on the function regulation requirements of high-pressure water presplitting and pick combined coal breaking experimental device,the overall scheme of control system design is put forward,and the cutting platform manipulation mode control is projected to realize the continuous operation and inching manipulation function control of the cutting platform;the cutting platform servo drive control is devised to meet the displacement control of the cutting staging and the cutting drum speed control;the experimental station is designed The design of the touch screen interface of the upper computer of the experimental platform is completed.The high-pressure water pump interruption control,cutting platform forward automatic circulation cutting control,cutting table automatic oblique cutting control,cutting platform manual control,cutting platform inching control and cutting platform reset control are realized.Taking the hardness parameter range of hard coal seam as the index,the uniaxial mechanical property test experiment of coal sample is carried out.Based on different aggregate ratio of coal sample,the mechanical parameters of coal sample are calculated.The test results show that the hardness index parameter of homogeneous coal sample with main aggregate coal and cement ratio of 1:5 reaches f 5.2 at the highest.Based on the similarity theory,the coal seam under actual working condition is reduced,and the simulated coal wall is constructed According to Darcy's law,the diameter and depth of the borehole are optimized.Based on the function design of the experimental system,the design of the experimental scheme is completed.The experimental results show that the thermal infrared temperature data of the presplitting coal wall with high-pressure water injection is 7.7?lower than that of the coal wall without presplitting with the same proportion and shape size,and the time domain amplitude of acoustic emission is 2.1 V lower than that in the frequency domain0.25V,the maximum cutting force of 70.1 k N,and the average specific energy consumption of 0.15 k W·h/m~3.The results show that the parameters have been improved significantly,which verifies that the crushing performance of coal after presplitting is good,and the method has practical application value.This paper has 79 pictures,17 tables and 106 references.