Many people still have some understanding of the bearing speed, the so-called bearing speed limit refers to the maximum allowable bearing speed, which is reduced with the increase of the bearing diameter series and width series. Each rolling bearing speed, there is a certain limit. When the bearing rotates, the temperature rise generated by the internal friction heat of the bearing will also increase with the acceleration of the rotation speed. The speed limit is the allowable value of the empirical speed for sustainable operation without causing adhesion or overheating. Therefore, the ultimate speed (RPM) of various bearings varies depending on the bearing structure, size, cage structure, materials, bearing load, lubrication method, and cooling of the bearing periphery.
The following are some of the factors related to the ultimate speed of rolling bearings:
1, lubrication: the use of oil and gas or oil mist lubrication of the bearing can continuously supply trace of new lubricating oil to the bearing, effectively ensure the thickness of the bearing lubricating oil film. Moreover, due to the large amount of oil supply, injection lubrication can quickly remove the heat generated by bearing operation and improve the bearing's limit speed.
2. Bearing load: The maximum speed of rolling bearing reached under certain load and lubrication conditions is closely related to the bearing type, size, direction, lubrication mode, clearance, cage structure, cooling conditions, load (size, type, direction) and so on. The limit speed of deep groove ball bearing can be increased by increasing bearing precision and adjusting bearing clearance properly.
3. Preload: If the preload is too large during the installation of the bearing, the contact stress between the rolling body and the raceway surface during the operation of the bearing will increase, and the calorification will also increase accordingly, thus further increasing the internal preload of the bearing, making the bearing more prone to wear and reducing the limit speed.
4, drive mode: the bearing's limit speed will change with the spindle drive mode, such as when the motorized spindle drive, the spindle internal heat, if used at the same time the outer cylinder cooling, will lead to the bearing inner and outer ring temperature difference, increase the bearing's internal load, resulting in the limit speed reduction; When the outer cylinder is used for cooling, the tolerance fit of bearing housing is different, the thermal expansion amount of bearing and bearing housing is different, the outer ring fit changes from clearance fit to interference fit, and the increase of internal preload causes the change of limit speed.
5, the size of the bearing clearance, bearing after installation clearance for tiny negative, rated life is the longest, the bearing capacity and limit rotational speed is the highest at this moment, but because of the actual clearance to minus the fit interference and deformation caused by temperature difference, the tiny negative clearance is very difficult to control, and once clearance too much negative rated life will be significantly reduced, so, at present are generally choose close to 0 is clearance.
6, bearing combination: bearing combination, due to a large amount of oil supply, can quickly remove the heat generated by the bearing, the limit speed can be further improved.