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The vibrating screen works by the compound-rotation vibration generated by the vibrator excitation. The upper rotating weight of the vibrator causes the screen surface to generate plane whirling vibration, while the lower rotating weight causes the screen surface to generate conical surface rotation vibration, and the combined effect makes the screen surface generate compound whirling vibration. Its vibration trajectory is a complex space curve. The curve is projected as a circle on the horizontal plane and as an ellipse on the vertical plane. The following are the factors that restrict the work of the vibrating screen:

1. The influence of the nature of the incoming raw materials

1. Moisture content

The moisture content of the material is also called humidity or moisture. The external moisture attached to the surface of the material particles has a great influence on the screening of the material, while the moisture in the material cracks and the moisture combined with the material have no effect on the screening process.

2. Mud content

If the material contains agglomerates that are prone to agglomeration (such as clay, etc.), screening may be difficult even at low moisture content. Because the clay material will be agglomerated during the screening, so that the fine mud is mixed into the screen product; in addition, the clay is also easy to block the screen holes.

3. Granularity characteristics

The particle size characteristics that affect the screening process mainly refer to the content of various grades of hand materials that have specific significance for the screening process in the raw material.

4. Density characteristics

When all the particles in the material have the same density, it generally has little effect on the screening, but when there is a density difference between the coarse and fine particles in the material, the situation is very different. If the density of the coarse particle size is small and the density of the fine particle size is large, it is easy to sieve. On the contrary, if the density of coarse grains is large and the density of fine grains is small, it is relatively difficult to sieve.

2. The influence of sieve performance

1. The movement form of the screen surface

The movement form of the screen surface is related to the looseness of the material layer on the screen and the speed, direction and frequency of the movement of the fine material that needs to pass through the screen relative to the screen surface. For example, the movement of the material on the fixed screen depends entirely on the material sliding and flowing under the action of its normal gravity, and the screening effect is poor; on the vibrating screen, the transport energy of the material mainly comes from the movement of the screen surface, and the material layer is continuously The ground is sufficiently loose, the particles collide violently against the screen surface continuously, and the effect inside the screen is better.

2. Structural parameters of the screen surface

(1) Screen width and length:

In general, the width of the sieve surface determines the processing capacity of the sieve. The wider the sieve surface, the greater the processing capacity; the length of the sieve surface determines the screening efficiency of the sieve. The longer the sieve surface, the higher the efficiency.

(2) The inclination of the screen surface:

The angle a between the screen surface and the horizontal plane is the screen surface inclination angle. The size of the inclination angle is closely related to the processing capacity and screening efficiency of the screening equipment. If A is large, the material group moves forward fast on the screen surface, and the screen surface has a large processing capacity, but the material undergoes screening on the screen surface for a short time, and the screening efficiency is low.

(3) Size, shape and opening rate of sieve holes

The larger the sieve hole, the higher the processing capacity per unit sieve area and the higher the screening efficiency. The size of the sieve hole mainly depends on the purpose and requirements of sieving. For conventional sieving with larger particle size, the sieve hole size is generally equal to the sieving particle size; however, when the required sieving particle size is smaller, the sieve hole should be smaller than the sieving size The particle size is slightly larger; for approximate sieving, the sieve opening is much larger than the sieving particle size.