Generally speaking, the rolling bearing itself in the outer spherical bearing block does not produce noise.The commonly felt "bearing noise" is actually the sound effect of the external spherical bearing housing directly or indirectly vibrating with the surrounding structure.
This is why many times the noise problem can be considered as a vibration problem involving the entire outer spherical bearing housing application.When a radial load is loaded on a bearing, the number of the load bearing rollers will change slightly during operation, that is, 2-3-2-3...This caused a shift in the direction of the load.The resulting vibration is inevitable, but can be mitigated by axial preloading, which is applied to all scrolls.
When the wave degree of the component is closely matched between the bearing ring and the bearing seat or the drive shaft, the outer spherical bearing seat ring may be deformed with the appearance of the adjacent parts.If deformation occurs, vibration may occur during operation.Therefore, it is important to machine the bearing block and drive shaft to the required tolerances.
Local damage due to operational or installation errors, a small portion of the outer spherical bearing raceway and rolling body may be damaged.In operation, rolling over damaged bearing parts will produce a specific vibration frequency.Vibration frequency analysis can identify damaged bearing parts.In many applications, the stiffness of the external spherical bearing seat is the same as that of the surrounding structure.Because of this feature, it is possible to reduce the vibration in the application by correctly selecting the bearings (including preload and clearance) and their configuration in the application.
1. Basis of oil or grease for outer spherical bearing seat:
The advantages of using lubricating oil to lubricate the outer spherical bearing seat include:
1) under certain operating specifications, the starting torque and friction loss of lubricating oil are significantly smaller than that of grease.
2) since the lubricating oil takes away heat in the circulation and plays a cooling role, it can make the outer spherical bearing seat achieve a relatively high rotation speed.
3) high operating temperature can be guaranteed.
4) when changing the grease, the relevant connection parts must be removed. When the oil is lubricated, there will be no such trouble.
5) it is suitable for the outer spherical bearing seat in the reduction box to be lubricated with lubricating oil, because the oil simultaneously lubricates the gear and the outer spherical bearing seat by splashing.
6) the grease in the outer spherical bearing seat is gradually contaminated by the worn products, abrasives, penetrations from the outside through the sealing device and the aging products. If the grease is not replaced in time, it will cause accelerated wear of the outer spherical bearing seat. When liquid lubricant is applied, it can be filtered to ensure its normal operation.
Advantages of grease lubrication for outer spherical bearing seat:
1) individual external spherical bearing seat points should be refuelled frequently by hand. If they are replaced with grease, it will not only save trouble but also avoid accidents caused by lack of oil.
2) the grease itself has the sealing function, which allows the use of the mechanism with low sealing degree to achieve the purpose of simplifying the design.
3) experience shows that it is within a certain speed range (n<20000 r/min or dn<The use of lithium grease lubrication has a lower temperature rise and a longer service life of the outer spherical bearing than that of the drop oil method.
2. Theoretical basis of external spherical bearing seat lubrication: the lubrication mechanism of external spherical bearing seat belongs to the theory of elastohydrodynamic lubrication.
3. Relationship between failure type and lubrication of outer spherical bearing seat: most failure reasons are caused by defective assembly and poor sealing.A small number of failures are caused by wear, adhesion, corrosion, and overheating due to lack or excess of lubricants or defective quality.