| Scraper conveyor,as one of the"three machines"in the fully mechanized coal mining face,is the only effective means of coal transportation at the present stage,which responsible for transporting the coal mined by the shearer in the working face.Existing scraper conveyor mechanics researches are mainly focus on the chain drive system dynamics research and static strength analysis of the related parts and components,and the coal load and the interaction force between coal and relevant parts are rarely involved.The practice shows that the coal load has important influence on the chain driving and the wear of middle plate.Based on the discrete element method and multi-body dynamics theory,the rigid-discrete coupling simulation model of scraper conveyor is established using EDEM and Recur Dyn software,and the distribution and load characteristics of coal in the middle trough,the force of the related parts in four different conditions,and the wear mechanism of medium plate are studied.The main research contents and conclusions of this paper are as follows:(1)Establish the rigid-discrete coupling model of scraper conveyor and verify the reliability of the discrete element model by the comparative test on the rotating disc abrasive wear machine.The results show that the minimum correlation coefficient R of groove section curve is 0.9879,the thrust ratio of coal on sample in simulation and experiment is 87%,two indicators show that the simulation model can well simulate test.(2)The flow and distribution characteristics of coal in the middle trough under different working conditions were analyzed.The coal distributes intermittently in heap shape with the area between two scrapers as the unit.The coal between two scrapers flows towards the area close to the previous scraper from uphill to downhill,and the coal distribution is more even.The coal distribution is not even in both sides of chute when the chute is inclined,and the coal mass ratio in both side areas changes from 98%of tilt 0°to 74%of tilt 10°.It needs a process to increase the coal carrying capacity,and the coal effective carrying capacity increases gradually.Under the coal accumulation condition,the piled coal is gradually transported away,and the trough transportation capacity is limited when the accumulation amount is large,and the remaining coal is piled up in the middle trough waiting for transportation.(3)The characteristics of coal load and parts force are analyzed under different working conditions.There is an obvious distribution gradient of coal load in the chute.In the region between two scrapers,the average coal compressive force in the first half is 19%of that in the second half in y direction.In the x direction,the average coal compressive force between the chains is 72%of that between the chain and the chute side.The coal load distribution is more even from the uphill to the downhill condition,and the load ratio of coal in the minimum and maximum load areas increases from 9%of the downhill 5°to32%of the downhill 15°.The coal load distribution in both sides of the chute is not even,and the both sides coal load ratio changes from 96%of the tilt 0°to70%of the tilt 10°,and the tension of the two chains is not even.Under different traffic volume conditions,the linear relationship between the coal mass flow rate in the chute and the coal compression force in the maximum load area is y=0.57x-45,and the quadratic relationship between the scraper resistance and the coal traffic volume is y=0.3162x~2-128.8x+15680.(4)In view of the the middle plate wear phenomenon,the wear mechanism of the middle plate is analyzed.And the middle plate wear area distribution caused by coal from large to small wear amount is two chain channels,areas between two chain channels and areas between chain channel and chute side.The wear mechanism:in the chain channels,coal particles are easy to be subjected to abnormal load,which intensifies the wear of the middle plate,and the compressive force of the squeezed particles is 59 times of the average of all the particles in the chute.The load of coal between the two chains is affected by the polygon effect of chain drive,and its load fluctuation frequency is 4 times of that between the chain and the chute side,resulting in more serious wear. |
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