Issue 61: Hengyu Guoqiang reducer - measures to prevent oil leakage of framework
Time：2018-09-08 | Source：恒宇国强 | Browse：1911984
1.Improve the surface quality of parts
The contact between the sealing lip and the mating surface is the key to the sealing effect. If the surface of the journal is too rough, the protruding part is easy to dry contact with the sealing lip through the extremely thin oil film, resulting in oil seal wear, so the surface roughness of the journal should be controlled within Ra0.2 ~ 0.8 μ m. The surface hardness shall be HRC55 and the quenching depth shall be at least 0.3 mm. In the condition of low speed, good lubrication and less pollution, it is allowed to reduce the hardness of the journal.
The journal surface matched with the oil seal of the sliding frame shall be non helical. The reason of causing the helix on the surface of the journal is: when finishing the grinding wheel, the movement track of the diamond on the dresser is a helix, so it forms a helix on the surface of the grinding wheel. In this way, the grinding wheel will form a helix on the surface of the journal when processing the journal. This helix will scratch the sealing surface when the shaft rotates and affect the sealing effect of the oil seal. Therefore, it is suggested to adopt the cutting in grinding method for the journal.
2 check the oil seal quality before assembly
Before installing the oil seal, the quality of the oil seal must be checked first. If there are gaps and cracks in the lip, rubber aging, spring rust or failure, etc., the oil seal cannot be used. At the same time, the tolerance of oil seal installation hole must be strictly controlled. If the hole diameter is too large, there will be a gap between the oil seal and the hole, causing oil leakage; On the contrary, if the hole diameter is too small, the oil seal will deform and cannot be used.
3. Improve the assembly process
The special working position apparatus and special tooling should be designed to ensure that the journal surface of the oil seal is not scratched, the oil seal lip is not damaged and the oil seal lip is installed in the correct direction; In the installation process, if the oil seal lip needs to pass through the thread, keyway, spline, etc., corresponding measures should be taken (such as using thick paper, adhesive tape, etc. to cover the thread surface) to prevent the lip from damage; If the lip lock spring is loose, it can be cut 10 ~ 15mm to connect the lock spring head and tail firmly. During assembly, special pressure sleeve must be used to gently press into the oil seal hole seat. It is not allowed to knock, let alone directly knock the oil seal with a hammer; In different cases, the installation requirements are different. In the case of straight hole and machined end face, the installation tool must press the oil seal to the machined surface; When the installation hole has a step, the installation tool must press the oil seal to the end face of the step; In the case of straight hole and end face not machined, the installation tool must press the oil seal to the end face of the shaft.
4. Change the lubricating oil in time
Due to the mechanical friction, stirring shear and air invasion, the lubricating oil is easy to oxidize and form a large number of abrasive particles. Once it enters the oil seal mating surface, it will cause oil seal leakage. It is suggested that the oil should be changed during the second trial run of the new equipment, so that the particles produced by severe wear at the initial stage can be discharged in time, and the lubricating oil should be changed every 3 months after the machine runs.
5 others
When the oil seal is mainly used to prevent the loss of lubricant, the sealing lip of the oil seal should be installed inward; If the main purpose is to prevent pollutants from entering, the sealing lip should be installed outwards. When used in the environment with more dust or rain, oil seal with auxiliary lip should be used. When the shaft diameter is large and the rotation speed is high, the framework oil seal made of silicone rubber should be preferred, followed by the oil seal made of fluororubber, acrylic acid vinegar rubber and nitrile rubber. In addition, we should also pay attention to control the vibration of the machine and the eccentricity of the spindle to reduce the probability of oil leakage.
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