Parameter Optimization Of Composite Vibrating Screen And Simulation Analysis Of Sieve Surface Movement

Combined vibrating screen is a new type of the vibrating sieve, which solves the problem that the machines has different amplitude, vibrating intensity, and dip angle and blockage of screen and improve the screening efficiency. In this paper, the combined vibrating screen was studied, and the high frequency and small amplitude of the screen was used, and the low frequency amplitude of the screen was adopted. Studying the optimum design of sieve parameters, and revealing the laws of motion of the screen surface material, the effect of all parameters on the vibrating sieve are determined through using EDEM software in the simulation analysis on the vibrating sieve particles and finding out the rules. The main contents of this paper are:(1)This paper establishes mathematical model based on unit productivity power consumption of combined vibration sieve through analysis of orthogonal experiment of combination of vibratory sieve parameters, sets as the objective function and obtains a set of optimum parameters by using genetic algorithm to optimize the design,that is: on the screen amplitude is 4.12 mm, with an inclination of 23.56 degrees, the vibrating intensity is 4.11; under the screen amplitude 8.2mm, with a lower sieve obliquity 19.73 degrees, the intensity of the vibrating sieve is 5.021. The total power consumption is reduced from 0.063kw/t/h to 0.057kw/t/h, and the power consumption is optimized by nearly 9%.(2)The simulation of the particle material in the composite vibrating screen is analyzed, and the contact model of the material particles is built, and the motion of the particles in the composite vibrating screen is analyzed by EDEM software. With the help of bonding model of particles, taking the number of bonding material and the average tangential force on the screen surface in the process of screening as a measure of the loose effect index, the effect of amplitude, vibrating intensity and slope angle of screen surface is analyzed, and loose effect is increased along with the increase of them. Among them, vibration intensity has the greatest impact on the degree of loose for the screen surface material, but screen angle is smallest. The flounce laws of a single particle on the combined vibration sieve surface are analyzed, and then the result shows that amplitude of sieve surface particles thrown after leaving sieve surface height has the greatest influence and the influence of the angle is smallest. The reason is, at the same other conditions, material is almost not be thrown up and only rolling in the sieve surface under the condition of small amplitude. With increasing amplitude, the material is slowly thrown and then beating on the sieve surface. The increasing of the amplitude, the vibration intensity and the inclination of the screen can not only increase the loose effect of the material and the height of particle flopping away the screen surface, but is conducive to rapid loose material.(3)The discrete-element analysis on the combination of the vibrating sieve surface material particles group is carried out by using the soft dry sphere model and the hierarchical theory. The average delamination rate curves of the particle groups on the sieve surface are obtained by analyzing of different particle size and particle swarm material. When reach a steady state, the upper and lower sieve particle segregation rate amplitude are respectively at around 0.58m/s and 0.45m/s. Then the regression model of vibrating parameters and average velocity is obtained by analyzing the relationship between amplitude, vibrating intensity and inclination and sieve and the average speed of materials on the surface. The dip angle of the screen is the most influential to the average particle size of the screen. The analysis of the material on the screen has a large speed and is conducive to the rapid stratification of material.(4)Applying the EDEM software and soft dry ball model to 3D discrete-element simulation of the combined vibrating sieve is carried out. Studying the screening surface length and the screening efficiency in basis of the concept of dynamic accumulative screening efficiency, the regression model of the screening efficiency and the screen length is obtained. The result shows that screening efficiency increases along with the screen surface length increases, and when the screen length is greater than 900 mm, sieve and sieve width ratio is greater than 4, the screening efficiency is not increased obviously.