Commonly used sealing rings can be divided into O-shaped sealing rings and lip shaped sealing rings according to their cross-sectional shape, and lip shaped sealing rings can be further divided into Y-shaped, V-shaped sealing rings, etc.
1, O-ring seal
O-ring, also known as O-ring, has a circular cross-section. O-ring seals are generally made of oil resistant rubber (such as nitrile rubber, polyurethane rubber, etc.) and have good compatibility with commonly used petroleum based hydraulic oils. It is mainly used for static and sliding seals, and is less commonly used in rotary seals. When used for sliding seals. The speed requirement for using O-ring is between 0.005M/s and 0.3m/s.
The inner, outer, and end parts of the O-ring can all serve as a seal. The sealing principle is. When the O-ring is installed in the sealing groove, its cross-section is compressed and deformed. When there is no liquid pressure, the initial sealing is achieved by generating pre contact pressure on the contact surface through the elasticity of the O-ring.
2, Y-shaped sealing ring
The overall shape of the Y-shaped sealing ring is circular, with a Y-shaped cross-section. It belongs to the lip shaped sealing ring category and is generally made of oil resistant nitrile rubber. It is a sealing ring with good sealing, stability, and pressure resistance, low friction resistance, and long service life, so it is widely used. The Y-shaped sealing ring is mainly used for sealing reciprocating motion devices. According to the different aspect ratios of the cross-section, the Y-shaped ring can be divided into two forms: wide cross-section and narrow cross-section. Figure Fi-4 shows the wide cross-section Y-shaped sealing ring.
The sealing effect of the Y-shaped ring depends on the close contact between its lip and the mating surface, and generates a large contact pressure under the action of pressure oil to achieve the sealing purpose. When the hydraulic pressure increases, the lip edge and coupling surface are pressed tighter, the contact pressure is higher, and the Y-ring has a certain degree of automatic compensation ability after wear, so it has good sealing performance.
3, V-shaped sealing ring
The V-shaped ring is made by pressing multiple layers of adhesive fabric. Its cross-section is V-shaped, as shown in Figures 6-6. The V-shaped sealing device is composed of a pressure ring, V-shaped ring, and support ring, and must be used as a complete set when needed. It is suitable for working under conditions where the working pressure is not greater than 50MPa and the temperature is -40 ℃ -80 ℃. When the working pressure is higher than 10MPa, the number of V-shaped sealing rings can be increased, but no more than 6, to improve the sealing effect. When installing, the opening of the V-ring should face the side with high pressure.
4, Oil seal
Oil seal usually refers to the sealing of lubricating oil, used on rotating shafts to seal oil internally and prevent dust externally. Oil seals are divided into frameless oil seals and skeleton oil seals. The oil seal is encapsulated on the shaft and must have a certain amount of interference. The lip of the oil seal generates a certain radial pressure on the shaft, forming a stable oil film. The working temperature of oil seals is generally 20 ℃ to 40 ℃ higher than the working medium temperature, so rubber and acrylic acid vinegar rubber are generally used. The working pressure of the oil seal should not exceed 0.05MPa. When installing the oil seal, make sure that the lip is facing the medium.