How to choose screen mesh and how to solve screen blocking?
As the main wearing part of the vibrating screen, the screen mesh is in direct contact with the material in the production process, which has an important impact on the production of the vibrating screen. Knowing the correct selection and use of screen meshes, knowing the causes and solutions of screen blocking faults during the operation of the vibrating screen, and solving problems quickly can save maintenance time, improve labor productivity, and ensure orderly and normal production.
How to choose screen mesh?
Screen mesh is an important part of the vibrating screen. The correct selection and use of the screen directly determines the gradation and quality of the product. A high-quality screen mesh must meet the following conditions:
(1) The material must be special wear-resistant steel wire. The chemical composition of C and Mn should be high enough, while Si, P, and S should be as low as possible.
(2) The weaving form is reasonable, and the steel wire must be tightly woven in the process, and must not be loose.
(3) The overall dimensions and hemming shape must be properly matched with the tension plate and screen frame on the vibrating screen.
(4) The screen mesh is flat and the opposite sides are parallel.
(5) The form of hemming is reasonable, which is conducive to the tension of the screen mesh.
The main factors of screen mesh blocking
Screen mesh blocking is one of the common faults in the operation of vibrating screen. Screen blocking is caused by various factors, including the shape of the material, the number of critical particles in the mesh, the thickness of the screen wire, and the shape of screen mesh hole etc.
1. the shape of stone
In the gravel production line, the content of needle-like particles should be as low as possible to prevent the phenomenon of screen mesh blocking.
In the stone crushing plant, jaw crusher is generally used as primary crushing equipment. The working principle of jaw crusher is extrusion crushing, which is easy to produce needle flake particles. And impact crusher and cone crusher are generally used as secondary crushing equipment. The working principle of impact crusher is impact crushing and the working principle of cone crusher is lamination crushing.
If the size of the stone crushed by the jaw crusher after primary crushing is too small, more needle flake particles will be produced. In order to reduce the ratio of needle flake particles, the size of products after primary crushing should not be too small.
2. matching of screen mesh and steel wire diameter
Practice has proved that the same mesh, too thick steel wire will cause a significant increase in the probability of screen mesh blocking.
3. The shape of the mesh hole
The screen mesh is generally made of square holes, and the small mesh is made of anti-blocking hole mesh. If the hole is blocked seriously, rectangular holes can also be used without affecting the particle size of the stone. However, considering the service cycle, we must pay attention to the direction of the mesh hole; otherwise the service life of the screen mesh will be affected.
4. Reasonably adjust the tension of the screen mesh
Reasonably adjust the tension of the screen mesh is an effective method to reduce the blocking of the screen mesh. The reasonable tension causes the screen mesh and the supporting beam to generate a slight secondary vibration, thereby effectively reducing the occurrence of blocking.
The specific method is to make the tensioning hook into a constant force tensioning mechanism, that is, add a spring to the tensioning bolt.
Other faults of screen mesh and corresponding measures
In addition to the blockage of the screen mesh, other failures of the screen mesh will occur during the operation of the vibrating screen. The common ones are as follows:
1. The screen wire is broken in a straight line at the tension plate
Cause of failure:
The tension bolt is loose; the screen mesh is too long; some support beams are de-welded or deformed; the tension plate is worn; one tension plate is installed with two screen meshes, etc.
Measures:
Tighten the bolts; re-determine the length of the screen mesh; weld the support beams in all positions; replace the tension plate; match the length of the screen mesh to the tension plate, etc.
2. Low screening rate
Cause of failure:
The screen opening rate is low, etc.
Measure:
Re-select the wire collocation of the screen mesh, etc.
3. Serious hole blocking
Cause of failure:
The content of needle flake stone particles is too much; the screen wire is too thick; the critical particles of stone and screen mesh are too many.
Measure:
Change the crushing method of stones; reasonable matching of screen mesh wire; change the form of screen mesh, etc.
4. The edge is straightened and the angle is deformed
Cause of failure:
The angle (or strength) of the tensioning hook is not enough, leading to the deformation of the tensioning hook; the tensioning position is not in place, the focus point is not accurate, etc.
Measure:
Re-replace the tensioning hook; pay attention to correct installation, make sure the focus point of the tensioning hook at the bottom of the screen hook, etc.
5. Serious wear in the middle of the screen mesh
Cause of failure:
Insufficient material shunting or subsidence in the middle of the screen, etc.
Measure:
Improve the diversion capacity or elevate the middle part of the screen mesh into an upward arc, etc.
