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Planetary gear reducer oil leakage fault--oil leakage at the rotating joint surface

Updated:06-02-2021
Summary:

The leakage level of this type of seal includes: 1. Lea […]

The leakage level of this type of seal includes:
1. Leakage at the seal between the bearing seat and the bearing seat.
2. Leakage at the seal between the output shaft and the shaft hole of the end cover.
The reason:
1. The quality of the oil seal: poor elasticity of the oil seal, defective lip, loose or falling spring.
2. Flanging or trimming of the oil seal lip due to assembly; or insufficient tightening torque of the connecting bolt of the oil seal seat.
3. The processing quality of parts.


Treatment measures:
1. Choose qualified oil seal products produced by regular manufacturers.
2. Use special oil packaging equipment and assembly methods in assembly.
(1) Pay attention to the contact position between the tooling and the oil seal when selecting the tooling. If the diameter of the contact is too small, the oil seal lip will be deformed.
(2) The correct force application method should be selected, and the appropriate size of the backing plate should be used to apply pressure evenly in the diagonal direction. Remember not to directly strike the oil seal to avoid deformation of the oil seal.
(3) During the assembly process, attention should also be paid to ensuring the level of the oil seal, so that the oil seal is evenly pressurized in the cavity to ensure the effectiveness of the seal. If the oil seal is forced into the cavity, the fitting part of the oil seal lip will be squeezed and jammed, resulting in oil leakage.
3. Use a special pneumatic wrench to tighten the bolts and use a torque wrench for testing.
4. Sealing design of parts:
(1) The principle of the interference between the lip and the shaft: usually the shaft diameter is less than 20mm, and the lip interference is 1mm; the shaft diameter is greater than 20mm, and the interference is 2mm. The fitting interference between the outer diameter of the oil seal and the shell should be 0.15mm~0.35mm;
(2) The contact width between the lip and the shaft: when the pressure difference is not large, the lip contact width is 0.2mm~1mm; if the medium pressure difference is large, the contact width should be increased.
(3) The roughness of the shaft is required to be 0.8μm~3.2μm. If the surface is too smooth, the oil is easy to squeeze out from the seal contact surface, and the oil film becomes thin or disappears, causing the lip to heat up or burn out; on the contrary, the lip wears too fast, causing leakage.
5. The design optimization of the structure can adopt the sealing form of floating oil seal.
Floating oil seals are often used in worm gear reducer to dynamically seal the end faces of the components. Floating oil seals are mechanical seals. They are generally composed of a ferroalloy floating ring and a matching nitrile rubber O-ring. The floating rings are used in pairs, one rotating while the other is relatively static.

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