For hydraulic and cooling systems, preventing liquid leakage is a very important task. Various sealing methods can be used for sealing, such as increasing packing, increasing the contact area to reduce pressure, etc. O-ring rubber seals are widely used because of their low price and simple structure.
However, during the use of O-ring rubber seals, some common problems have often been encountered that lead to seal failure. Let's take a look at what factors can affect the sealing effect of O-ring seals.
1. Selection of O-ring material
The physical and chemical properties of the material of the O-ring seal must be considered in the seal design, including the hardness and elasticity of the seal ring material, and the chemical compatibility of the seal ring material with the sealing medium.
In particular, the chemical reaction between the sealing medium and the sealing material should be avoided, resulting in damage to the sealing ring and sealing failure. In terms of chemical compatibility, medium immersion sealing ring materials are generally used to test, and conventional materials can also be qualitatively used according to engineering experience;
In the selection of materials, attention should also be paid to the ambient temperature of the sealing ring. As the ambient temperature decreases, the hardness of the rubber material increases and the elasticity decreases; as the temperature increases, the rubber will gradually become softer, and the sealing performance will also change.
In the case of a large range of ambient temperature changes, materials with small changes in the elasticity of the sealing ring with temperature should be selected.
2. The quality of the sealing surface of the parts
The sealing surface corresponding to the O-ring should ensure a certain machining accuracy to ensure the sealing effect under a certain pressure.
Ensuring the contact pressure can ensure the sealing effect, but if the roughness of the sealing surface increases, the sealing ring needs to produce a larger deformation to fill the microscopic gap of the sealing surface, and the compression rate of the sealing ring must be kept within a certain range, otherwise it will reduce the service life of the seal ring, or even crack, resulting in seal failure.
When the system pressure is low, increasing the deformation of the sealing ring within the range that the sealing ring can withstand can compensate for the risk of leakage caused by the increase in surface roughness; when the system pressure is high, it must be considered to increase the surface of the sealing surface. quality to improve sealing performance.
3. The form of the sealing groove
In the sealing ring installation and the sealing groove, the groove shape is different, and the pressure and deformation on the sealing ring are also different, which in turn affects the sealing effect. The stress peaks are larger and the seals installed in the V-groove are more likely to be damaged as the fluid pressure increases. In addition, there are dovetails, triangular, and other specially designed sealing grooves.