Purpose of the sealing ring

Sealing rings are primarily used to seal gases against oil, water, and corrosion, preventing leakage. The functions of various sealing rings are as follows: O-rings are mainly used for static sealing and reciprocating motion sealing. When used for rotary motion sealing, they are limited to low-speed rotary sealing devices. V-rings are generally installed in rectangular grooves on the outer or inner circumference for sealing. V-rings are axially acting elastic rubber seals used for pressureless sealing of rotating shafts.

V-shaped rubber seals: These are a type of rubber seal for reciprocating motion. They have a V-shaped cross-section and are rarely used alone. They are generally composed of a pressure ring with fabric reinforcement, a support ring, and several V-shaped sealing rings. The number of sealing rings depends on the sealing pressure. V-shaped sealing rings are molded from rubber cloth or pure rubber. The rubber material is generally NBR. The pressure ring and support ring are generally pressed from harder rubber cloth, while the support ring can also be pressed from hard plastic. V-shaped sealing assemblies are mainly used for piston rods and plungers in heavy equipment. This type of sealing assembly provides excellent stability and wear resistance, and prevents the sealing ring from being squeezed into the gap. Even under harsh conditions such as axial or radial vibration, sudden pressure, and temperature changes, it still provides optimal sealing performance. It is suitable for media such as hydraulic oil, water, and emulsions, with operating pressures up to 40 MPa and above, a typical surface linear velocity of 0.5 m·s⁻¹, and an operating temperature range of -30 to 120 ℃.

U-shaped rubber seal: This is a type of rubber seal used for reciprocating motion. It has a U-shaped cross-section, hence the name U-shaped seal. It comes in two types: rubber and fabric-reinforced. Fabric-reinforced U-shaped seals are often used in combination with a pure rubber support ring. These fabric-reinforced U-shaped seals are mainly used on the piston rod and hydraulic plunger of hydraulic cylinders, with media such as hydraulic oil, water, and emulsions. Due to the good surface structure of the rubber fabric, it maintains good lubrication when sliding on metal surfaces, reducing friction and wear, and improving performance. Under low pressure, the support ring provides good sealing due to the pre-compression of the lip, and under high pressure, it has a self-sealing effect. Its working oil pressure is generally 25 MPa, with a maximum pressure limit of 35 MPa, a linear velocity of 0.5 m·s⁻¹, and an operating temperature of -30 to 120 ℃. The operating conditions for pure rubber U-shaped seals are largely the same as those for Y-shaped seals.

Y-shaped rubber seals are a type of rubber seal used in reciprocating motion, with a Y-shaped cross-section, hence the name "Y-shaped seal." They are generally used in hydraulic or pneumatic operating systems, providing a sealing function in the piston, piston rod, and cylinder. They can be molded from high-hardness nitrile rubber, cast from polyurethane rubber, or made into a fabric-reinforced combination. This type of product has a simple structure, good sealing effect, and self-sealing effect when pressure increases, but pure rubber products are prone to extrusion at the root under high pressure. Generally, pure rubber Y-shaped seals are suitable for applications with oil pressure less than 16 MPa, linear velocity less than 0.5 m·s⁻¹, and temperature between -30 and 120 ℃. Multi-lip reciprocating rubber seals are composite rubber seals with two or more sealing lips. Different cross-sectional structures are available depending on the operating conditions. Most seals consist of NBR (Non-Bremse Ride) and a fabric-covered rubber layer, which can be directly molded into one piece or molded separately, vulcanized, and then combined into a sealing body. The sealing surface has multiple sealing lips and lubricating grooves, allowing a small amount of lubricating oil to remain on the sealing lip surface during operation, reducing friction and dissipating heat. During use, there are generally two plastic retaining rings on the upper and lower parts of the seal to prevent the sealing rings from being squeezed into the gap under high pressure. Depending on the structure, the working pressure is generally 20–40 MPa, and the linear velocity is 0.1–0.2 m·s⁻¹. They can operate in hydraulic oil, water, and emulsions.