The application function and basic classification of hydraulic seals1

The application function and basic classification of hydraulic seals

The use of hydraulic seals requires minimal leakage and requires very little leakage of hydraulic seals, which has excellent sealing effect, and automatically improves its sealing effect as the pressure of the hydraulic oil of the mechanical seal increases, even in severe work such as high pressure and high temperature. There is no significant increase in the leakage of hydraulic seals in the environment. Excellent compatibility Because the hydraulic seals are immersed in the hydraulic oil for a long time, it is easy to swell, dissolve or become brittle and hard, so that the sealing effect is lost. Therefore, the hydraulic seals are required to have good performance on the hydraulic oil. compatibility. Small frictional resistance In order to prevent or reduce the occurrence of low-pressure creeping and other undesirable phenomena in hydraulic equipment, hydraulic seals are required to have low static frictional resistance and dynamic frictional resistance, and their friction coefficient should be very stable. Long service life Hydraulic seals should have good elasticity, heat resistance, cold resistance, pressure resistance, wear resistance and certain physical and mechanical strength, and have a long service life. Low-cost hydraulic seals should be easy to manufacture and install, and the corresponding sealing grooves are easy to process and manufacture, and the requirements for the machining accuracy of the sealing surface are low, and the price is low. Basic classification of hydraulic seals ① UN series: UN type polyurethane oil seal is the most commonly used oil seal in hydraulic cylinders. It is a typical lip seal and can achieve excellent sealing performance whether it is used for piston or piston rod. In the case of low pressure, the U-shaped ring is sealed only by the interference deformation of the lip. With the increase of pressure, the elastic deformation of the lip increases, the stretching, compression and bending stress increase, and the radial pressure of the U-shaped ring automatically increases. The length of contact with the sealing surface is continuously increased until the entire axial length of the U-ring is in contact with the sealing surface, thus ensuring excellent sealing under high pressure conditions. UN is universal for hole and shaft. Its shape is symmetrical on both sides of the lip. It can accept working pressure from 21mpa to 35mpa, and can withstand temperature from -35°C to 100°C. Made from M-90 material. ② DH type polyurethane oil seal The two-way effect anti-pressure sealing ring, on the one hand, scrapes the surface dirt of the piston rod moving inward, and on the other hand prevents the leakage of hydraulic oil in the cavity. No skeleton/double-effect anti-pressure ring, the material is M-90, the hardness is 90±2, and the temperature is -35 to 100 ℃. ③ D-1 type: D-1 type hole seal, its shape is a short and thick outer lip, and it is also a kind of U-shaped ring. The pressure resistance can reach 40Mpa. It is often used in hydraulic cylinders. A typical lip seal, it can achieve excellent sealing effect when installed on the piston rod. It can accept the working pressure of 40Mpa, the operating temperature can reach -35 to 100 ℃, the movement speed is 0.03-0.5m/s, and it is made of M-95 raw materials. ④ D-2 type: D-2 type polyurethane oil seal is a seal for shaft. Its shape is a short and thick inner lip, and it is also a kind of U-ring, with a pressure resistance of 40Mpa. -35 to 100°C is acceptable. The movement speed is 0.03-0.5m/s, and it is made of M-95 raw material. ⑤ ME-1 series: It is a skeleton/dual effect oil seal. The material structure is M-90 and iron shell. It has anti-pressure effect, heavy load and auxiliary seal, and is suitable for occasions with poor environmental conditions (such as outdoor, etc.). The movement speed of ME-1 is 0.03-1.0m/s, and the temperature resistance scale is -35 to 100℃. ⑥ ME-2 series: ME-2 type polyurethane oil seal is a skeleton/reverse lip oil seal. Its raw material is M-90 plus iron shell, which has anti-pressure effect and strong scraping ability under heavy load. It is suitable for harsh environments ( such as mud/ash, etc.). The speed of ME-2 reaches 0.03-1.0m/s, and the working temperature is -35 to 100℃. ⑦ UPH series: The cylinder reciprocates with a hydraulic oil seal, which can be used for piston and piston rod seals. This seal has a large cross-section and can be used for large-scale operations. The nitrile rubber and fluororubber raw materials used ensure a wide range of working temperatures and a wide range of specifications. ⑧ LBH series: reciprocating seal, which is a kind of seal that prevents dust from entering, protects equipment and maintains the sealing function, this is a kind of anti-scratch oil double-lip full rubber anti-pressure seal. Seals made of nitrile rubber and fluororubber are suitable for a wide range of operating temperatures. In addition to the most common hydraulic oil seals mentioned above, there are D-3 D-4 D-5 D-6 D-7 D-8 D-9 D-10 D-14 DH-03 DH-04 DH-05 DH -07 ME-3 ME-4 ME-5 ME-8 etc.