| Scraper conveyor is the key equipment of fully mechanized coal mining equipment.It is an indispensable equipment for long distance transportation of coal.However,the operation condition of the scraper conveyor in the underground is very complex and harsh.The medium plate is not only corroded by moisture and acid gas,but also by the combined action of scraper,scraper chain and coal.As a result,the middle plate is heavily worn.It greatly influences the smooth operation of coal mines and has an important impact on the national economy.In order to improve the wear resistance of the middle plate and extend the service life of the scraper conveyor.In this paper,the bionic wear resistance technology is applied to the surface of the middle plate of the scraper conveyor.This paper provides a new idea for the wear-resistant design of scraper conveyor.In this paper,dung beetle,scallop and pangolin scales are selected as bionic models.The morphology of the front and back of the dung beetle was recovered by using the focused morphology recovery technique,and its microstructure was analyzed.A large number of inhomogeneous pits are distributed on the front thoracodorsal plate of dung beetles.Analysis of typical individual pits shows that,the pit presents a cone-angle circular mouth structure and the pit depth to diameter ratio is close to 1.The scallop and pangolin scales were reverse-shaped by using reverse modeling technology.The feature point cloud structure is extracted and the mathematical model is constructed,and the structure conforms to the trigonometric function is obtained.The ratio of period and amplitude of trigonometric function is 3.5 and 3.9 respectively.According to the analysis of wear-resisting geometric structure,the pit and striated middle plate were designed.Single factor and response surface optimization tests were carried out on the pit plate under specific conditions(coal bulk particle size is 6-8mm,load of is 20N,scraper chain speed is 0.65m/s and test duration is 6600s).When the ratio of depth to diameter is 1.41,the diameter of the pit is 0.69mm,the pitch Angle is 6.55°and the radial distance is 4.66mm,the wear amount is minimum.The quadratic polynomial regression prediction model of wear amount and each factor was established and the variance analysis was carried out.The order of influence significance of each factor was obtained:radial distance(L)>depth-diameter ratio(?)>diameter(D)>pitch Angle(A).The bionic plate with optimal structure was verified by repeated tests and compared with the light slide.It is found that the prediction error of the polynomial model of bionic plate wear is 3.2%.The wear of bionic plate is reduced by 12.6%compared with that of light slide.Single factor and response surface method were used to simulate and optimize the striated medium plate under specific working conditions(Particle size of coal bulk model is 6-8mm,The load is 20N,The speed of scraper chain is 0.65m/s and The simulation duration of each medium plate is 0.18s)(Simulation analysis is selected for the difficulty of preparation and treatment of medium plate).The average wear depth of the plate is minimum when the ratio of width to height of the strip is 4.94,the width of the strip is 1.81mm and the pitch of the strip is 6.33mm.The quadratic polynomial regression prediction model of average wear depth and each factor was established and the variance analysis was carried out.The order of influence significance of each factor was obtained:the stripe width(W)>ratio of stripe width to stripe height(R)>stripe pitch(L).The average wear depth was taken as the response value to compare the repeated simulation of the optimal stripe plate and the smooth plate.It is found that the average wear depth of the striated middle plate is 2.28×10-8mm less than that of the smooth slide.The wear mechanism of the bionic plate of the optimal structure was analyzed by the observation of microscopic wear morphology and the method of EDEM-Recur Dyn coupling.Observation and comparison of the microscopic wear morphology between the pit plate and the light slide plate show that the grain wear and adhesive wear of the pit plate are relatively light.The microscopic wear morphologies of the pit plate and the light slide were compared,the results show that the abrasive wear and adhesive wear of the plate in the pit are relatively light.At the exit of the pit is the impact pit of coal particles on the middle plate.It shows that the attitude of coal particles in the pit has changed and the coal particles have changed from the cutting state to the rolling state.By simulating the abrasive wear process of the optimal pit plate and light slide.Since the pit can break the continuous cutting state of coal particles,the maximum force(or resistance)of the upper sample is smaller than that of the light slide in the process of interaction between the upper sample and the pit plate.By analyzing and observing the wear cloud image of discrete elements in the middle plate,we can find that the wear trace is mostly represented by the wear and disconnection.The wear marks of the smooth medium plate indicate the presence of coal particles that have been continuously cut.By simulating the wear process of the optimal striated medium plate and smooth sliding plate,the wear resistance mechanism of striated medium plate was revealed,and the upper sample on the surface of striated medium plate operate smoothly and fluctuate little.In addition,the maximum resistance of the upper sample and the maximum pressure of particles on the striated plate are smaller than that of the smooth slide.The continuous wear marks on the surface of the light slide are widely distributed,and the wear marks on the surface of the plate in the striations are mainly concentrated on the inside of the striations. |
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