After the composite product is made on the forming mold, although the surface of the forming mold is smooth and the mold release material is coated or spread, it is not all easy to remove the composite product from the mold. Practice has shown that the release of composite products must overcome adhesion and adsorption. The adhesion force is generated after the resin matrix and the mold bonding surface are cured and formed; the adsorption force is due to the adsorption force generated under atmospheric pressure when the prepreg is applied to the mold, the interface is almost vacuum state. Therefore, the demolding of composite products must rely on external forces to overcome the adhesion and adsorption force of the product to the mold. It can be seen that the demolding method is actually how to use external force.
The following introduces the liquid ring vacuum pump used for vacuum demoulding. For more detailed information, please contact us via email contact@evpvacuum.com.
The gas in the liquid ring vacuum pump tends to make some movement. From one place to another, the gas inside will move with it during the use of the pump. This can balance the air pressure and keep the pump in a stable state. And it is also conducive to the use of other functions. How does this pump achieve gas migration?
1. Diffusion
The movement of gas in another medium due to the concentration gradient is called diffusion. The medium can be another gas, in which case the diffusion is called interdiffusion, or it can be a condensable substance. In the case of liquid ring vacuum pumps, the penetration of helium through the glass can reach 10-13 liters/sec. Hydrogen can permeate iron at 300~400℃, nickel at 450℃, glass at 600℃, and copper at about 640℃. Diffusion coefficient. The ratio of the absolute value of the mass flow rate through a unit area to the normal concentration gradient of the unit area, the symbol is D, and the unit: m2·S-1.
2. Viscosity and heat conduction of gas
In any medium, the phenomenon of momentum transfer and momentum exchange between layers is called the viscosity of this medium. In liquid ring vacuum pumps, the ratio of the tangential force per unit area in the direction of the airflow velocity gradient to the velocity gradient is the viscosity coefficient. Symbol: η, unit: Kg·m-1·s-1.
When the gas concentration is not the same, there will often be gas migration. This phenomenon is conducive to the normal maintenance of the liquid ring vacuum pump, and makes the use of the pump more in line with the requirements, balances the air pressure, and prevents danger. Use them efficiently.
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