The role of hydraulic seals The use of hydraulic oil seals

1, The use of hydraulic oil seal

Prevent hydraulic oil leakage

Oil seal, commonly known as oil guard ring, is an indispensable non-metal accessory to keep rotating parts in automobiles. The commonly used skeleton oil seal is generally composed of metal skeleton ring, steel wire spring ring and rubber sealing layer.

The role of oil seal.

1. prevent mud, sand, dust, moisture, etc. from invading into the bearing from outside.

2. To limit the leakage of lubricating oil from the bearing.

The requirements for oil seal are that the size (inner diameter, outer diameter and thickness) should be in accordance with the regulations; it is required to have proper elasticity, so that the shaft can be properly stuck and play a sealing role; it should be heat resistant, wear resistant, good strength, medium resistant (oil or water, etc.) and have a long service life.

To use oil seal reasonably, the following points should be noted.

1. The speed of shaft

Due to the design and structure, high speed oil seal should be used for high RPM shaft, low speed oil seal should be used for low RPM shaft, and low speed oil seal should not be used for high speed shaft, and vice versa.

2. Ambient temperature

In the case of high use temperature, polypropylene ester or silicon, fluorine or silicone fluorine rubber should be chosen. And should try to reduce the oil temperature in the oil tank. In the case of low use temperature, cold-resistant rubber should be selected.

3. Pressure

The general oil seal has poor ability to bear pressure, and the oil seal will be deformed when the pressure is too large. Pressure-resistant support ring or strengthened pressure-resistant oil seal should be used under the use condition of excessive pressure.

4. Eccentricity of installation

If the eccentricity of oil seal and shaft is too large, the seal will become poor, especially when the shaft speed is high. If the eccentricity is too large, the oil seal with "W" shape section can be used.

5. The surface finish of the shaft directly affects the service life of the oil seal, i.e. if the shaft finish is high, the service life of the oil seal will be long.

6. pay attention to the lip of the oil seal should have a certain amount of lubricant. 7.

7. Pay special attention to prevent dust from immersing into the oil seal.

2, What are the types and roles of hydraulic cylinder seals

V-type seal

It is a kind of axially acting elastic rubber seal, used as a pressureless seal for rotating shaft. The seal lip has good mobility and adaptability, can compensate for large tolerances and angular deviations, can prevent internal grease or oil from leaking outward, and can also prevent the invasion of external splashing water or dust. O-ring seal

Mainly used for static sealing and reciprocating motion sealing. When used for rotary motion sealing, it is limited to low-speed rotary sealing devices. Torque Seal

Generally installed in a groove with a rectangular cross-section on the outer or inner circle for sealing purposes. Y-type seal

Widely used in reciprocating seals.

In addition, there is a spring tension (spring accumulation) seal, which is a spring in the PTFE sealing material, there are O-type spring, V-type spring, U-type spring

3, Selection of hydraulic seals

Types of seals, in general, there are mainly the following, for

(1) IIR butyl rubber seal

It is suitable for chemical resistance or vacuum environment, its use temperature is -50 ℃ -110 ℃, its main advantages are

a. Good gas tightness, able to resist heat and ozone, and its insulation performance is good.

b. Good resistance to polar solvents, such as alcohols, ketones and esters.

Although it has the above advantages, it cannot be used with petroleum solvents, kerosene or aromatics at the same time.

(2) NBR Buna-N seals

This seal can be used in hydraulic oil, lubricating oil, gasoline, water, grease and silicone oil, etc. Its operating temperature is -40℃ to 110℃.

(3) FLS fluorosilicone rubber seal

It can be used in aerospace, its use temperature is -50 ℃ -200 ℃, its main feature is able to resist oil, solvent, and its high and low temperature performance is also very good.

(4)CR neoprene seal

It is suitable for a variety of flame-resistant, chemical corrosion-resistant sealing environment, but also not afraid of direct sunlight, its use temperature of -55 ℃ -120 ℃, but not for strong acids, nitrocarbons, esters, chloroform and ketones in chemicals.

4, The role of hydraulic cylinder spacer

1. Common main seal structures are U, Yx seal, PTFE combination seal, DAS combination seal, V-type combination seal, etc.. There are also guide ring (support ring), anti-dust seal, static seal and other auxiliary seals. These forms can also be used in combination to achieve the required performance.

2. Seal advantages.

(1) seal ring in the working pressure and a certain temperature range, should have a good sealing performance, and with the increase in pressure can automatically improve the sealing performance.

(2) The friction between the seal ring device and the moving parts should be small and the friction coefficient should be stable.

(3) The seal ring corrosion resistance, not easy to aging, long working life, good wear resistance, wear and tear to a certain extent can automatically compensate.

(4) Simple structure, easy to use and maintain, so that the seal has a longer life.

Terminology explanation

Oil seal

Oil seal (oil seal), also known as shaft seal (shaft seal) is a device used in machines to prevent fluid (mostly lubricating oil) from spilling out of the joints (mostly the joint surface of the parts or the shaft). Seals for static and dynamic sealing (generally reciprocating motion) are called seals. The representative form of oil seal is TC oil seal, which is a rubber completely covered double lip oil seal with self-tightening spring, and the generally said oil seal often refers to this tc skeleton oil seal.