Mechanical seals are also called end face seals. Mechanical seals are oil seals for rotating machinery. For example, centrifugal pumps, centrifuges, reactors, compressors and other equipment. Since the transmission shaft runs through the inside and outside of the equipment, there is a circumferential gap between the shaft and the equipment. The medium in the equipment leaks out through the gap. If the pressure in the equipment is lower than the atmospheric pressure, the air leaks into the equipment. Therefore, there must be a shaft seal device to prevent leakage.
The sealing ring is the general term for the dynamic ring and the static ring (the same below), which is the most important component of the mechanical seal. The sealing ring determines the performance and life of the mechanical seal to a large extent. Therefore, some requirements are put forward for it.
1. Sufficient strength and rigidity
Under working conditions (such as pressure, temperature and sliding speed, etc.), it will not be damaged, the deformation should be as small as possible, and the sealing performance can still be maintained when the working conditions fluctuate. In particular, the sealing end face must have sufficient strength and a certain corrosion resistance to ensure that the product has a satisfactory service life.
2. Good resistance to heat shock
To this end, the material is required to have a higher thermal conductivity and a smaller linear expansion coefficient, so that it will not crack when subjected to heat shock.
3. Smaller friction coefficient
The sealing ring should have a smaller friction coefficient.
4. Good self-lubrication
If a short period of dry friction occurs during work, the sealing end face will not be damaged. Therefore, the sealing ring must have good self-lubrication, and the sealing ring material and the sealing fluid must have good wettability.
5. Simple structure: The sealing ring structure should be simple and symmetrical, and the integral structure should be given priority. A combined (such as embedded) sealing ring can also be used, and the sealing end face spraying structure should be avoided as much as possible.
