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★ Y-ring product description
- Categories:Rubber knowledge
- Time of issue:2020-04-21 11:58
★ Y-ring product description
- Categories:Rubber knowledge
- Time of issue:2020-04-21 11:58
The Y-shaped sealing ring has a Y-shaped cross-section, which is a typical lip-shaped sealing ring. It is widely used in reciprocating dynamic sealing devices, and its service life is longer than that of O-ring. The applicable working pressure of Y-shaped sealing ring is not more than 40MPa, and the working temperature is -30 ～ 80 ℃.
Y-shaped seals can be divided into wide Y-shaped seals, narrow Y-shaped seals and Yx-shaped seals according to the length-to-width ratio of the cross section. The pressure resistance of the wide-section Y-type sealing ring is slightly lower than that of the narrow-type Y-type sealing ring, which can only be applied to the working environment of P <20MPa, while the narrow-type Y-type sealing ring can be used in the working pressure of P <32MPa.
According to whether the height of the two lips is the same, the Y-shaped seal ring can be divided into unequal-height lip Y-shaped seal ring for shaft, unequal-height Y-shaped seal ring for hole and universal-equal lip Y-shaped seal for shaft hole ring. Y-shaped seals are made of different materials, and can also be divided into nitrile rubber Y-shaped seals, fluorine rubber Y-shaped seals, polyurethane rubber Y-shaped seals, etc. 
Working speed range: 0.01 to 0.6 m / s when made with nitrile rubber; 0.05 to 0.3 m / s when made with fluororubber; 0.01 to lm / s when made with urethane rubber. The sealing performance, service life and working pressure limit of Y-type seal ring are all made of polyurethane rubber material.
1) Reliable sealing performance;
2) Low friction resistance and smooth movement;
3) Good pressure resistance, wide application pressure range;
4) Simple structure and low price;
5) Easy installation.
3. Sealing principle
Y-shaped sealing ring is attached to the sealing coupling surface by its opened lips. When there is no internal pressure, only a small contact pressure is generated due to the deformation of the lip tip. In the case of sealing, there is a normal pressure equal to the pressure of the medium at every point of contact with the sealing medium, so the bottom of the lip ring will be compressed axially, the lip will be compressed circumferentially, and the contact with the sealing surface will be widened. At the same time, the contact stress increases. When the internal pressure increases again, the distribution form and size of the contact pressure further change, and the lip and the sealing surface cooperate more closely, so the sealing performance is better. This is the “self-sealing effect” of the Y-ring. Due to this self-sealing effect, a Y-shaped ring can effectively seal the high pressure of 32MPa.
The effective sealing pressure of the pressure-enable seal is equal to the sum of the pre-pressure and the fluid pressure. The Y-shaped sealing ring effectively applies the fluid pressure to the seal through the role of the lip. The pre-pressure can be reduced to a small value, and the higher the fluid pressure, the smaller the effect of the pre-pressure. In high-pressure occasions, the role of the pre-pressure can be ignored Excluding. At this time, it is advantageous to reduce the sealing friction, because the sealing friction is proportional to the contact pressure of the seal. Therefore, while ensuring the sealing, the Y-shaped sealing ring has less friction force than the squeeze type seal.
Y-shaped sealing ring is mainly used for reciprocating sealing. It can be known from its working principle that when the Y-shaped ring is installed, the lip must face the side with high pressure to play a role, so the Y-shaped sealing ring can only function in one direction.
When the coupling parts move relatively at the working speed, a sealing oil film is formed between the sealing lip and the sliding surface. The presence of the oil film can improve the friction conditions of the seal ring and reduce wear; the oil film plays a sealing role in the pneumatic seal. In the reciprocating motion of the hydraulic element, the thickness of the oil film is different when the moving part is extended and retracted, and this difference in oil film thickness can cause leakage. Therefore, when the Y-shaped ring works normally, a small amount of leakage occurs, and when the reciprocating speed is large, the leakage amount is large. This is because when the reciprocating speed is large, the number of reciprocating becomes very frequent, and at the same time, the hydrodynamic effect of the oil film increases the thickness of the oil film, forming a rapid accumulation of the oil film. When the viscosity of the working oil increases, the thickness of the oil film increases accordingly, and the amount of leakage caused by the reciprocating speed also increases. However, because the viscosity of the hydraulic oil decreases with increasing temperature, when the hydraulic equipment starts at a low temperature, the leakage at the beginning of the movement is large. As the temperature increases due to various losses during the movement, the leakage will gradually cut back.
The leakage of the piston during the reciprocating stroke is different. When the internal pressure is low, the leakage in the extraction stroke increases with the increase of the internal pressure; the pressure in the stroke decreases with the increase of the internal pressure. When the internal pressure is large enough (approximately greater than 7.5 MPa), the leakage no longer changes with the internal pressure.
When the internal pressure p1 of the Y-shaped seal ring is low, the frictional force increases as the internal pressure increases. When the internal pressure is large enough, the frictional force no longer changes much. If the lubrication is good, there is even a downward trend. The starting friction test results of the Y-ring abroad show that the starting friction has little relationship with the stopping time, which is the biggest difference from the O-ring.
This is extremely advantageous for machines with intermittent motion. At the same time, when the internal pressure is low, the starting friction increases with the increase of the internal pressure. When the internal pressure exceeds 5MPa, the starting friction will be independent of the internal pressure. Therefore, for high-pressure intermittent machinery, there will be no problem of excessive starting friction. After the sealing lip is worn, due to the pressure of the medium, the lip has a certain automatic compensation ability.
4. Use description
NBR nitrile rubber sealing strip-suitable for use in petroleum-based hydraulic oil, glycol-based hydraulic oil, diester-based lubricants, gasoline, water, silicone grease, silicone oil and other media. It is the most widely used and lowest cost rubber seal at present. Not suitable for polar solvents such as ketones, ozone, nitro hydrocarbons, MEK and chloroform. The general temperature range is -40 ~ 120 ℃.
HNBR hydrogenated nitrile rubber sealing strip-has excellent corrosion resistance, tear resistance and compression deformation characteristics, good resistance to ozone, sunlight and weather. It has better abrasion resistance than nitrile rubber. It is suitable for washing machinery, automobile engine system and refrigeration system using new environmental protection refrigerant R134a. Not recommended for use in alcohols, esters or aromatic solutions. The general temperature range is -40 ~ 150 ℃.
SIL silicone rubber sealing strip-has excellent heat resistance, cold resistance, ozone resistance, atmospheric aging resistance. Has good insulation properties. However, the tensile strength is inferior to ordinary rubber and not oil resistant. Suitable for household appliances such as electric water heaters, electric irons, microwave ovens, etc. It is also suitable for all kinds of articles that come into contact with the human body, such as kettles and water dispensers. Not recommended for use in most concentrated solvents, oils, concentrated acids and sodium hydroxide. The general temperature range is -55 ~ 250 ℃.
VITON fluorine rubber sealing strip-high temperature resistance is better than silicone rubber, has excellent weather resistance, ozone resistance and chemical resistance, poor cold resistance. Resistant to most oils and solvents, especially acids, aliphatic hydrocarbons, aromatic hydrocarbons and animal and vegetable oils. It is suitable for the sealing needs of diesel engines, fuel systems and chemical plants. Not recommended for ketones, low molecular weight esters and nitrate-containing mixtures. The general use temperature range is -20 ~ 250 ℃.
FLS fluorosilicone rubber sealing strip-its performance combines the advantages of fluorine rubber and silicone rubber, oil resistance, solvent resistance, fuel oil resistance and high and low temperature resistance. Can resist the erosion of oxygen-containing compounds, aromatic hydrocarbon-containing solvents and chlorine-containing solvents. Generally used for aviation, aerospace and military purposes. It is not recommended to be exposed to ketones and brake fluid. The general temperature range is -50 ~ 200 ℃
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