Small and medium-sized deep groove ball bearing sealing technology design
2.1 Seal structure design
The sealing structure of the bearing is different under different conditions of use. The sealing structure of the bearing generally has no groove in the inner ring.
The inner ring is slotted and the inner ring is straight. The inner ring has a grooved sealing structure which has better performance than the inner ring grooveless sealing structure, but the inner ring has a grooved seal.
The processing accuracy of the structure is high, resulting in high manufacturing costs. According to the inner diameter of the sealing ring, the lip structure is generally divided into single lip, double lip, three lips, and multiple lips.
The performance is multi-lip>three-lip>double-lip>single lip, so the multi-lip structure should be used when the bearing sealing performance is high.
2.2 Choice of manufacturing process
The sealing groove of the inner and outer rings is both a fixed rubber sealing ring (outer ring sealing groove) and a matching clearance or interference function (inner ring sealing groove).
Requirement, its size and shape tolerance are important, mainly by forming tools. If the dimensional accuracy and shape accuracy of the sealing groove, the inner and outer diameters are inverted
The angle, the inner and outer groove positions and the parallelism to the end face are not good. After assembly, the non-contact part will be ground, the gap is too large or too small, and the contact lip is connected.
The contact surface cannot be guaranteed, the sealing ring can not be positioned in the outer ring sealing groove, and the rotation will occur, and the above phenomenon will seriously affect the sealing performance of the bearing.
The structure, material and manufacturing precision of the sealing ring are important factors affecting the performance of small and medium-sized deep groove ball sealed bearings. Its material, precision and sealing shaft
The sealing performance of the bearing has a great influence, because the internal pressure and temperature of the bearing during testing or use are higher than the external pressure and temperature, the sealing ring
In particular, the lip is subject to a large pressure. If the strength and elasticity are insufficient, the lip will be deformed outwardly, so the skeleton of the sealing ring should have good rigidity.
The rubber should be uniform, the physical properties meet the requirements, and it must have a certain hardness and elasticity. It must be firmly bonded to the skeleton, and the structural shape and dimensional accuracy should meet the requirements.
2.3 Selection of lubricating grease
The filling amount of the grease in the sealed bearing has a great influence on the three sealing properties and the service life of the bearing. Low grease filling, three seals
It can be beneficial, but it is easy to cause poor lubrication during use, leading to early failure of the bearing and affecting the reliability of life. Too much fat filling, full during operation
After the state and excess, the excess grease leaks out when it is squeezed. In fact, the bearing is in operation, most of the bearing grease is squeezed in the seal ring jacket
On the rim and the cage, the moving space of the bearing is almost free of grease, and the grease is completely in the static space.
The effect of the amount of grease filling on dust prevention is that as the amount of grease is increased, the amount of dust intrusion is also increased, and the dustproof performance is lowered. When there is a lot of grease filling, the bearing cavity is full
And then, the leaked grease generally adheres to the outside of the sealing portion between the sealing ring and the inner ring, and the external dust adheres to the leaked grease, which is produced as the bearing runs.
The axial movement of the raw part causes some grease that has adhered to the dust to be sucked into the bearing. As the amount of grease is increased, the amount of grease leakage increases, and the dust invades the bearing cavity.
The more it is, the worse its dustproof performance. The uneven distribution of grease also has a great influence on the sealing performance.
The accuracy of the grease filling machine is not up to the requirement, there is no control of the amount of grease filling, and there is no grease filling on both sides, resulting in uneven distribution of grease inside the bearing, even if the amount of filling is not much,
Local saturation can also cause localized large amounts of grease leakage. The error of the grease filling amount should be controlled within plus or minus 5%
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