Each kind of net frame has its own characteristics. When selecting, the net frame of different materials can be selected according to different situations.
The steel mesh frame made of hollow aluminum profile has the characteristics of light weight, stable size, beautiful appearance and easy operation.
When the hollow section is used to make the net frame, the reasonable section shape can reduce the deformation of the net frame. Because of the same cross-section area but different shape, the moment of inertia is different. Relationship between section shape and strength relationship between section shape and strength relationship between section shape and strength relationship between section shape and strength.
3、 Mesh frame material
The materials used to make the mesh frame shall meet the tension requirements of the tension of the mesh, be firm, durable, light and cheap; when the temperature and humidity change greatly, its performance shall be stable; and it shall have certain water resistance, solvent resistance, chemical resistance, acid resistance, alkali resistance and other properties.
4、 Selection of mesh frame
Screen frame is one of the most important materials for making steel screen plates. The selection of screen frame has a direct impact on the quality of plate making and printing.
In order to ensure the plate making, printing quality and other requirements can be selected according to the following conditions.
1. Strong tension resistance
As the material of the mesh frame, it should have sufficient strength that can resist the tension of the steel mesh, because when the mesh is stretched, the steel mesh will produce a certain tension on the mesh frame, which requires the mesh frame to have the tensile strength, if the strength is not enough, the frame will be flexed, it will be deformed, and it will not print a good print.
Generally, it is required that the frame surface of the mesh frame is flat, the four corners are stable, and the frame arms (strips) are straight. However, due to the tension of the steel mesh and the asymmetric connection of the steel mesh to the frame, there are three kinds of moments, i.e. moment B, angle moment C and torque t. The bending moment makes the frame bar bend to the center of the plate; the angle distance makes the corner close to the corner, and the frame angle warps; the torque makes the frame bar rotate around the center of the afraid surface, trying to separate from the steel mesh. These moments lead to the deformation of the mesh frame. The size of the deformation depends on the texture of the material and the strength of the structure. The force exerted by the tension of the steel mesh on the mesh frame (local).
2. Prestressed treatment
The bending deformation of the net frame will affect the tension stability of the steel net. In order to reduce this effect, the net frame can be prestressed.
There are two ways to deal with this:
First, according to the strength principle of the arch structure, the net frame is made into a convex shape, with a deflection of about 4m M / m, each internal angle slightly greater than 90 °; or the metal frame that has been made is stretched into this shape with a special tool, which can resist the influence of the tension of the steel mesh.
Another method is to do the pre stress treatment while doing the pneumatic net pulling, that is, the front end of the net puller is tightly against the outside of the frame, and the multiple frames are bent under the action of the top force. When the fixed net is installed, the force surface of the net frame moves from the outside to the above, but the force direction and size are basically the same, so the bending will not be increased. Because of these advantages, pneumatic tension machine has become the most popular tension equipment at home and abroad. The mesh frame shall be prestressed.
3. Strong and durable
The net frame should contact with water and solvent frequently, and be affected by the change of temperature. When affected by these external fixings, it is required that the mesh frame shall be solid and durable without skew, etc., so as to ensure the reuse of the mesh frame, reduce waste and cost.
4. Easy to operate
Under the condition of ensuring the strength, the net frame shall be light in weight and easy to operate and use.
5. Good adhesion
The bonding surface between the mesh and the steel mesh shall have a certain roughness to strengthen the bonding force between the steel mesh and the mesh.