When the particle size levels of the screening products of broken materials exceed two, the problem of screening sequence arises. There are three vibration screening sequences:
1. Overlap method
Sifting from coarse to fine. In the screening process from coarse to fine, the screen surfaces overlap one by one, the upper screen surface has larger screen holes, and the lower screen surfaces have gradually smaller screen holes.
(1). The wear of the screen surface is small. Although all the materials and the largest pieces are added to the screen surface with the largest mesh hole, this screen surface is often composed of steel rods and is not easy to wear. Protect the fine-pore screen surface below;
(2) The screening efficiency of fine-level materials is higher because the amount of materials added to the fine-pore screen surface is smaller;
(3) Coarse-grade materials are less broken during the screening process, because coarse-grade materials can be quickly separated from the screening process, which is of great significance to coal mine screening;
(4). Since the screen surface is multi-layered, the layout of the screening device is relatively compact.
2. Sequence method
Screening from fine to coarse. In the screening process from fine to coarse, the screen surfaces are arranged sequentially in the order of increasing screen holes.
It is convenient for maintenance and easy to observe the working conditions of each screen surface. In addition, each screen can be discharged separately along the entire length of the screen surface.
3. Combined method (mixed screening)
In the combined process, part of the screen surface is arranged from coarse to fine, and the other part of the screen surface is arranged from fine to coarse. In production practice, a coarse-to-fine or combined screening process is usually used.
The linear vibrating screen is driven by dual vibrators. When the two vibrators rotate synchronously and in opposite directions, the exciting forces generated by their eccentric blocks cancel each other out in the direction parallel to the motor axis. The resultant force is superimposed in the direction perpendicular to the motor axis, so the motion trajectory of the screen machine is a straight line. The two motor shafts have an inclination angle relative to the screen surface. Under the combined force of the excitation force and the material's own gravity, the material is thrown up on the screen surface and moves forward in a straight line, thereby achieving the purpose of screening and grading the material. Can be used to automate operations in the assembly line. It has the characteristics of low energy consumption, high efficiency, simple structure, easy maintenance, and fully enclosed structure without dust spillage. The maximum screening mesh size is 400 meshes, which can screen out 7 materials with different particle sizes.