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How are seals classified? what's the effect?

Release time:

2021-09-15

Construction machinery is inseparable from the oil cylinder, and the oil cylinder is inseparable from the seals. The common sealing ring is also called oil seal, which plays the role of blocking oil to prevent oil from overflowing and passing through. The seals usually used in the cylinder are of the following types: dustproof, piston rod, buffer, guide support ring, end cap and piston.

How are seals classified? what's the effect?

The dustproof ring is installed on the outside of the cylinder end cover to prevent external pollutants from entering the cylinder. According to the installation method, it is divided into card insertion and pressing.

1. Snap-in dust rings are common. In the grooves in the inner wall of the end caps, for use in less severe environmental conditions, the material used is usually polyurethane, and there are many variants of construction. For example, the H and K types are bilip structures, but they remain the same.

2. Under harsh and heavy load conditions, the press-fit dust ring does not get stuck in the groove. The metal layer is wrapped on the outside of the polyurethane material to improve the strength. It is pushed into the end cover of the hydraulic cylinder and is divided into single lip and double lip. lip.

3. The piston rod seal, also known as U-cup, is installed in the end cap of the hydraulic cylinder to prevent hydraulic oil leakage, made of polyurethane or nitrile rubber, and sometimes required together with a support ring (also known as a retaining ring) In use, the support ring is used to prevent the sealing ring from being squeezed and deformed under pressure.

4. The buffer seal is used as an auxiliary piston rod seal to protect the piston rod when the system pressure suddenly increases. There are usually three types. Type A is a single seal made of polyurethane. Types B and C are two-piece, which prevent seal pinching and allow the seal to withstand higher pressures.

5. The guide support ring is installed on the end cover of the hydraulic cylinder and the piston to support the linear movement of the piston rod and guide piston to prevent contact between metals. The materials include plastic, bronze coated with PTFE, etc.

6. The end cover sealing ring is used to seal the cylinder end cover and the wall. It is a static seal to prevent the leakage of hydraulic oil from the gap between the end cover and the cylinder wall. Usually consists of a nitrile rubber O-ring and a support ring (retaining ring).

7. The piston sealing ring is used to cut off the two chambers of the hydraulic cylinder and is the main seal in the hydraulic cylinder. Usually two pieces, the outer ring is made of teflon or nylon and the inner ring is made of nitrile rubber. There are also various variants, including the use of teflon-coated bronze, and the single-acting cylinders also have polyurethane U-cups.

The sealing performance is automatically improved. The friction between the seal and the moving part should be small and the friction coefficient should be stable. The sealing ring has strong corrosion resistance, is not easy to age, has a long service life, and has good wear resistance.