Rotating shaft lip seals are usually called oil seals and are widely used in gearboxes, drive axles and other components of construction machinery, such as the front and rear output shafts of the gearbox, the final drive of the drive axle, and the wheel edges. Its function is to isolate the oil cavity from the outside, seal the oil inside, and prevent dust from the outside. At present, there are many types of oil seal structures widely used in China, and their basic structures include rubber sealing parts, metal frame or PTFE frame oil seals and metal spring oil seals.

The sealing mechanism of the oil seal: The seal of the oil seal is formed by the interference fit between the sealing element (rubber, PTFE, polychlorotrifluoroethylene, etc.) and the rotating shaft. Its sealing mechanism is: dry friction, boundary lubrication and fluid lubrication coexist on the contact surface between the oil seal lip and the shaft at the same time, and they are constantly alternated. Dry friction produces wear and fluid lubrication produces leakage. A stable fluid dynamic pressure oil film is formed between the interface between the oil seal lip and the shaft under boundary lubrication. The thickness of the oil film is about 0.0025mm. This oil film is not only used for lubrication, but also Play a sealing role. If the oil film is too thick, fluid will leak; if the oil film is too thin, a fluid lubricating film cannot be formed, and the lip will wear.

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