| Scraper conveyor is the core equipment in coal mining face.While the middle pan serves as the carrier of coal bulk material,its working performance and service life would directly affect the work efficiency of the scraper conveyor.In the running process of the scraper conveyor,the middle pan is subjected to tension and compression,local bending,time-varying load and impact,which makes it prone to wear and tear.In addition,its thickness,heavy weight makes it difficult to be replaced,and its reliability can easily affect the normal operation of coal mining.Therefore,it is very important to investigate the dynamic bearing characteristics and wear resistance of the middle pan.This paper is mainly based on the impact theory and wear mechanism by simultaneously using simulation and experiment to study the dynamic bearing characteristics and wear resistance of the middle pan of the scraper conveyor,which provided theoretical guidance for the improvement of the working performance of the middle pan.This paper mainly focuses on the key components of scraper conveyors and coal bulk materials.Firstly,based on the mechanics of granular media and impact dynamics,the frictional resistance of the scraper conveyor and the impact force of the middle pan were calculated theoretically,then the influential factors that affect the force of middle pan were obtained.Secondly,combined with tribology theory,the wear mechanism of the middle pan was analyzed,and the influencing factors affecting the wear characteristics of the middle pan were obtained.Based on theoretical analysis,EDEM was used to simulate the running process of the scraper conveyor,and the correctness of the discrete element model was verified in combination with the actual working conditions,and the law of the force acting on the middle pan was analyzed.In order to study the dynamic bearing characteristics of the middle pan,the working process of the scraper conveyor under different working conditions was simulated by controlling variables,and the dynamic bearing characteristics of the middle pan of the scraper conveyor were obtained under conditions of unsteady coal fall,different coal material parameters,and different working surface inclination angles.The middle pan was worn in the process of bearing the coal bulk.In order to study the wear characteristics of the middle pan,EDEM was used to establish the middle pan wear model of the scraper conveyor under different working conditions,and the average line wear depth was used to characterize the wear characteristics of the middle pan.Based on the friction and wear theory of the middle pan,the effects on the wear characteristics of the middle pan were analyzed under different chain velocities,working face inclination angles,coal material parameters,and material constants of middle pan.The results illustrated that different working parameters have different effects on the wear characteristics of the middle pan,which gives some guidance for the improvement of the wear-resisting property of the middle pan.In order to improve the wear-resisting property of the middle pan,two different alloy powers were used to obtain two kinds of cladding layers A1 and A2 by plasma cladding technology on the wear-resistant material NM450 steel plate that middle pan plate commonly used.The organizational structure and microhardness of the two cladding layers were analyzed.Through friction and wear experiments,the effects of different sliding speeds and different loads on the friction coefficient and wear rate of the substrate and the cladding layer were studied,and the wear mechanism of their surface was analyzed and compared.The results show that the microhardness of the two cladding layers is much higher than that of the substrate,and two kinds of cladding layers all have anti-friction effect.The wear-resisting property of the cladding layer A2 is better than that of A1. |
PDF Full Text Request