As a sealing mechanical element, the oil seal is widely used in the machinery of almost all fields such as automobiles, industrials, homes, etc. Many of us can not do without a car almost daily, and there are nearly 200 rubber products used in a car. Of the high-speed rotary operation, the mechanical friction part of the oil to enter, in order to prevent these oils from the mechanical gap in the leak must use the oil seal in the car, the oil seal is a very important mechanical components. Narrow sealing contact surface (less than 0.5mm) and the rotating shaft to a certain pressure contact, and under the effect of liquid lubrication oil leakage, as the elastomer seal, the cross-sectional shape of the oil seal and hoop spring lip to the shaft Has a good follow-up compensation performance, which can be a smaller lip radial force to obtain a good sealing effect. There are many types of oil seals, oil seals in various forms with a skeleton of spring oil seal with the most common application. According to the working principle can be divided into ordinary type and liquid dynamic pressure type, dynamic pressure seal rotary seal is made by the lip air side of the thread, ripple, triangular bump or groove and other special patterns to obtain dynamic pressure reflux Fruit, at work can leak the liquid back into the sealed chamber, thus significantly improving the sealing performance. Dynamic pressure type oil seal with its small amount of leakage long working life, the shaft and oil seal their own defects are not sensitive to apply Low viscosity medium, high linear velocity and other harsh conditions and has been widely used. Hydrodynamic oil seal is divided into one-way dynamic pressure and two-way dynamic pressure type, one-way dynamic pressure type oil seal is mainly a screw seal, which relies on lip The air side of the helical ribs of the leakage of oil to guide the lip back to the main oil film to go in. Spiral oil seal shaft rotation direction and spiral pattern of the same direction of rotation while the two-way hydrodynamic oil seal positive and negative shaft rotation Can generate dynamic pressure back flow, two-way hydrodynamic oil seal mainly rely on the lip side of the air side of the triangular bump (or groove), wavy ribs, waveform lip, etc. Wave lip lip seals, for example, the bending wave The shape of the main lip both to prevent the accumulation of oil dripping, but also allow to maintain a slightly thick film, in the generation of dynamic pressure reflux, but also make the friction resistance is only half the ordinary type of oil seal. , Is conducive to friction heat dissipation, which can make the lip Degrees down about 25%. The life of a rubber seal In addition to materials (NBR, ACM, FPM, etc.), an important indicator of the life of the oil seal lip temperature rise. Oil seal lip and shaft friction caused by lip temperature rise, lips The mouth temperature rise is related to the radial force, linear velocity, friction coefficient and thermal conductivity of the lip. Taking nitrile rubber (NBR) as an example, when the oil seal size is 80 × 100 × 10, the oil temperature is 110 ℃, the environment Temperature of 50 ℃, lip tip temperature of up to 150 ℃. The working range of rubber seal is as follows: working pressure 0 ~ 0.3MPa sealing surface line speed low speed <4 m / s; high speed 4 ~ 15 m / s work Temperature -60 ~ 150 ℃