Key points of use of seals
新闻概况： The inner surface of the hydraulic cylinder is usually processed by rolling, which not only improves the surface roughness, but also makes the surface hardened by cold work, which is beneficial to prolong the service life of the sealing ring. In addition, the pressure used, the length and type of the sliding surface also have a great influence on the service life. Therefore, the "regular inspection" time should be decided according to these conditions.
(1) Select the appropriate seal material and hydraulic oil, as well as the adaptability to the working temperature and the compatibility of the oil.
(2) The geometric position accuracy (concentricity) of the sliding parts relative to the seal is high, the material is good (such as hard chrome plating) and the surface roughness is fine, which can prolong the service life.
① For the oil seals used in hydraulic pumps and motor journals, not only the roughness of the sliding surface is required to be within Ra of 0.25m, but also hard chrome plating is required on the surface, and the diameter of the oil seal lip needs to be adjusted according to the specific conditions. Adjust the spring force to make it tight enough, and use a mounting sleeve or a thin gasket to protect the sealing ring during installation to prevent the lip from rolling and twisting, causing the spring to slip out.
②The inner surface of the hydraulic cylinder is usually processed by rolling, which not only improves the surface roughness, but also makes the surface hardened by cold work, which is beneficial to prolong the service life of the sealing ring. In addition, the pressure used, the length and type of the sliding surface also have a great influence on the service life. Therefore, the "regular inspection" time should be decided according to these conditions.
③ The sealing surface is required to be well lubricated to prevent dirt from invading people. The use of fluids that meet the specified cleanliness levels and the correct installation method are also necessary conditions.
The concept of valve oil seal
The valve oil seal can prevent oil from entering the intake and exhaust pipes, causing oil loss, preventing the leakage of gasoline and air mixture and exhaust gas, and preventing engine oil from entering the combustion chamber. Valve oil seal is one of the important parts of the engine valve group. It is in contact with gasoline and oil at high temperature. Therefore, it is necessary to use materials with excellent heat resistance and oil resistance, generally made of fluororubber.
The reasonable use of high temperature oil seals needs to pay attention to these matters!
Special care must be taken to prevent dirt from infiltrating the oil seal. Oil seals are classified according to the rotational speed of the shaft. Oil seals can be divided into low-speed oil seals (less than 6m/s) and high-speed oil seals (greater than 6m/s). According to the pressure level that the oil seal can withstand, it can be divided into normal pressure type oil seal and pressure type oil seal. According to the structure and sealing principle of the oil seal, it can be divided into standard oil seal and dynamic return oil seal. In addition, according to the material classification of the oil seal components, it can be divided into a skeleton type oil seal and a skeleton type oil seal, a spring type oil seal and a springless type oil seal.
The role of various sealing rings
The V-shaped seal is an axially acting elastic rubber seal used as a pressureless seal for the shaft. The sealing lip has good mobility and adaptability, can compensate for large tolerances and angular deviations, can prevent the internal grease or oil from leaking out, and can also prevent the intrusion of external splashing water or dust.
Installation and use of high-speed oil seal
Due to the presence of an oil film controlled by the oil seal edge between the oil seal and the shaft, the oil film has fluid lubricating properties. Under the action of the surface tension of the liquid, the rigidity of the oil film just makes the oil film and the air contact end form a meniscus, which prevents the leakage of the working medium and thus realizes the sealing of the rotating shaft. The sealing ability of the oil seal depends on the thickness of the oil film on the sealing surface. If the thickness is too large, the oil seal will leak; if the thickness is too small, dry friction may occur, causing the oil seal and shaft to wear; if there is no oil film between the sealing lip and the shaft, it will easily cause heat and wear. Therefore, when installing, apply some oil to the sealing ring, and at the same time ensure that the skeleton oil seal is perpendicular to the axis line. If it is not perpendicular, the sealing lip of the oil seal will drain the lubricating oil from the shaft, which will also cause excessive wear of the sealing lip. . During operation, the lubricant in the casing seeps out a little, so it is ideal to form an oil film on the sealing surface.
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