| With the development of industrial technology,medium material screening is becoming increasingly important,and the emergence of the vibrating screen has greatly promoted the development of the screening technology.Vibrating screen of the screening process is essentially a process of separation,namely compare particles with the size of the mesh,smaller particles can be through the screen mesh,bigger particles could not appear on the screen as screening,finally through the discharge end.In the screening process,the size of particles closed to screen hole instead of discharge is buried into the mesh,causing plugging hole and resulting in a loss of the screening efficiency.Therefore,how to effectively reduce the blocking and improve the sieving efficiency of vibrating screen is a problem worthy of being studied.Many scholars used the traditional screening test on the research,due to the factors affecting hole wall is more,the traditional screening test consumes a lot of time,consumption of resources.With the development of computer technology,three-dimensional discrete element method(DEM)has won the acceptance of many experts and scholars,it is widely used in medium-in the study of mechanical system operation process.This article uses the three-dimensional discrete element method for screening study.The main contents include:(1)The screening model of vibrating screen was built for the sake of screening simulation for the particles with 5 mm size.The distribution range of blocking is determined.The particles with a 5.1 mm diameter is selected for single particle size distribution of plugging hole research.(2)The blocking hole conditions simulation of different shapes particles passing through different same size of screen surface illustrates that for the same size of screen surface,spherical particles with cube particles passing through rectangular mesh,the worst blocking condition appeared for the conical particles.(3)The relationship between the feed rate and the hole wall are built.Simulation experiments show that the feed rate is less than 9000 a/s,blocking the total number of particles increases with the increase of feed rate,and when the feed rate is more than 9000 a/s,plugging holes particle number growth is slow,barely changed much,and established the plugging hole on the basis of the number of particles and the feed rate of the regression model.(4)The relationship between the vibration parameters(vibrating amplitude,vibrating frequency,and vibrating direction angle)and screen surface parameters(inclination angle of the screen’ surface,diameter of the screen wire)and the blocking rate are studied.By comparing the screening efficiency curve with blocking rate curve,the effects of each parameters on them are obtained,which provides a guide for improving the design of the vibrating screen.The motions of the material group on the screen are analyzed,and the regression model for the average rate of material group and amplitude,frequency,inclinations is constructed.(5)The response surface method has been established to fit the relationship between the material particles screening efficiency and blocking rate.The effect of various parameters on the screening efficiency and the influence of the porosity size are analyzed.Results show that the amplitude,frequency,vibrating direction angle have significant effects on the screening efficiency and blocking rate.Meanwhile,the interaction factors are also discussed.Finally,taking the maximized screening efficiency and minimized blocking rate as objectives,the parameters optimization problem is solved. |
