Vibrating screen is through the vibration applied to the sieve body, so that the material is loose, layered, through the sieve, and conveying the material to achieve the purpose of material screening screening screening machinery, the main function is to classify the material, desliming, according to the quality or particle size sorting, is an indispensable auxiliary production equipment for feed production. Common types of vibrating screen: elliptical vibrating screen, circular vibrating screen, linear vibrating screen, etc., of which the linear vibrating screen has a simple structure, reliable and other advantages, commonly used in the feed industry, such as for corn, soybeans and other raw materials in addition to the stone, in addition to the ash, screening; screening and grading after granulation and so on. Linear vibrating screen is the use of two vibration motors synchronized reverse rotation, generating reverse excitation force, forcing the box to drive the screen for longitudinal, linear back and forth movement, the material on the screen surface for continuous oblique upward throwing movement. The materials are loosened when they are thrown up, and the small particles penetrate the screen when they meet and collide with the screen surface, so as to realize the classification and transportation of materials. The screening effect of vibrating screen not only has a great impact on the product value, but also directly on the efficiency of the next operation has an important impact. Therefore, it is of great practical significance to study the factors affecting the screening efficiency of vibrating screen and find measures to improve the efficiency of vibrating screen.

　　1 Factors affecting the efficiency of vibrating screen

　　The screening effect of vibrating screen is related to many factors, including material properties, screen surface structure parameters, vibrating screen movement parameters and other aspects.

　　1.1 Material properties

　　Vibrating screen in the production process will often appear in the enrichment phenomenon, that is, the screen mesh is stacked blocked, the effective screening area becomes smaller, and the process efficiency is reduced, which is mainly related to the material type and particles, the material loose density, the material humidity, the material granularity composition, etc. The material type and particle, the material loose density, the material humidity, the material granularity composition, and so on.

　　1.1.1 Material types and particles

　　Different types of materials, physical properties are different. The type of material can be divided into two categories: brittle and viscous, viscous materials in the vibrating screening process, easy to form a dense material adhesion, clogging screen, so that the permeability rate is reduced, while brittle materials are not, process efficiency can be guaranteed. The particle shape of the material will also affect its penetration rate, cubic shape and spherical material is easy to penetrate the screen, while the flaky material is easy to get stuck in the sieve hole, so that the screening process efficiency is reduced.

　　1.1.2 Material bulk density

　　Material particles are basically layered according to the size of the particle volume and through the sieve, that is, the loose density of the material directly affects the processing capacity of the vibrating screen. Loose density of bulk material is easy to penetrate the screen, screening efficiency is also higher; on the contrary, the loose density of smaller materials and powder materials are not easy to penetrate the screen, screening efficiency is also low.

　　1.1.3 Material humidity

　　Material moisture content is too high, easy to form adhesion, in the vibration process, the object is squeezed each other to make the adhesion group more dense, increasing the resistance of the material movement, so that the material particles layered and through the sieve appears difficult; material adhesion also makes the sieve hole size becomes smaller, blocking the sieve hole, reducing the effective screening area, and sometimes even can not be screened. Therefore, when the water content of the material is too high, the screening process should consider some remedies, such as taking measures to dry the material.

　　1.1.4 Material granularity composition

　　Material in the screening process of the probability of sieve through the influence of many factors, including the more direct and important factors is the relative size of the material particle size and sieve size. The ratio of material particle size and sieve size is called the relative particle size. The smaller the relative particle size, the higher the probability of sieve through, when the relative particle size is close to 1, the probability of sieve through tends to be close to zero. Therefore, the relative particle size is usually equal to 0.7 ~ 1.0 of the material is called difficult to screen material or critical material. Material difficult to sieve material composition on the probability of sieve through also has an impact, the greater the content of difficult to sieve material in the material, the smaller the probability of sieve through, the lower the screening efficiency will be. In order to get a higher screening efficiency, the content of difficult to screen materials in the aggregate should be minimized. In addition, the difference of granularity index also has a certain effect on the screening efficiency, the difference of granularity index is too large, it will cause the production cycle is large, which restricts the quality of the product and processing capacity. Therefore, the gradation of aggregate should be strictly controlled.

　　1.2 Sieve surface structure parameters

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