Types and selection of common hydraulic seals
Types and selection of common hydraulic seals: The commonly used hydraulic seals for hydraulic cylinders mainly include O-rings, lip seals and combined seals.
1, O-ring
O-shaped sealing ring has O-shaped cross-section, simple shape, rubber material, and inferior wear resistance to polyurethane, so it is mainly used for static sealing in hydraulic systems.
2. Lip seal
U-shaped sealing ring: The sealing performance of the U-shaped sealing ring is better, but it is easy to roll when used alone. The frictional resistance of the U-shaped sealing ring is relatively large and increases with the increase of working pressure. Therefore, the U-shaped sealing ring is only suitable for hydraulic cylinders with lower working pressure or lower moving speed.
V-shaped sealing ring: V-shaped sealing ring must be used with supporting ring and pressure ring. V-shaped sealing ring has better sealing performance. The number of sealing rings used can be determined according to the working pressure. The sealing ring can be compensated by adjusting the pressure ring The disadvantage of V-shaped sealing ring is that the structure is complicated and the friction resistance is relatively large. Therefore, the V-shaped sealing ring is only suitable for hydraulic cylinders with low moving speed and high working pressure.
V-shaped sealing ring
YX type sealing ring: YX type sealing ring has a cross-section width to height ratio greater than 2, and based on the requirements for stability in use, the working lip of the YX type sealing ring is shorter than the non-working lip, so it is divided into holes with YX type sealing YX type sealing ring is used for ring and shaft. YX type sealing ring will not roll when used, so YX type sealing ring is suitable for high pressure and high speed hydraulic cylinder.
3. Combined seal
Lace-shaped ring: Lace-shaped ring is composed of synthetic rubber O-shaped sealing ring and cloth rubber Y-shaped sealing ring superimposed, relying on its own deformation to produce a higher initial contact stress on the sealing surface to prevent no pressure Leakage of liquid. When the hydraulic cylinder is working, the pressure oil causes the elastic deformation of the O-ring seal, always squeezes and expands the sealing lip of the Y-ring seal to make it close to the sealing surface, and together with the initial contact stress to prevent the leakage of the pressure oil .
Glyd ring: Glyd ring is composed of O-shaped rubber seal ring and square seal ring filled with PTFE. Glyd ring can be divided into Glyd ring for hole and Glyd ring for shaft, but they are sealed The mechanism is the same, and its deformation produces a higher initial contact stress on the sealing surface to prevent the leakage of pressureless liquid. When the hydraulic cylinder is working, the pressure oil causes the elastic deformation of the O-shaped sealing ring to squeeze the square sealing ring to make it close to the sealing surface, and together with the initial contact stress to prevent the leakage of pressure oil.
Step Seal: The structure of Step Seal is similar to Glyd ring. It is also composed of O-shaped rubber sealing ring and special shaped rectangular or trapezoidal sealing ring filled with polytetrafluoroethylene. Step Seal can be divided into holes like grid ring. The step seal and the shaft use the step seal. The sealing effect and sealing mechanism of the step seal are the same as the Glyd ring, but the step seal only has a one-way sealing effect. The common feature of Step Seal and Glyd ring is filled with PTFE material, with low friction, no creeping, and long life.
