2019年8月18日星期日
Calculation of bearing lubricant quantity and design of oil supply mode
4.1 Calculation of bearing lubricant quantity
The amount of oil required to lubricate a rolling bearing depends to a large extent on the type of bearing, the design of the fuel supply system, and the type of lubricant. It is difficult to give a simple and straightforward formula that is suitable for any situation and has wide applicability. Bearings with automatic oil transfer (such as angular contact ball bearings) require more oil than bearings that do not have automatic oil transfer (such as double row cylindrical roller bearings). Especially when the value of the velocity coefficient (n.dm) is large, the difference is more obvious (Fig. 3). Through a large number of experiments, the rough calculation formula of the fuel supply quantity Q is as follows:
Figure 4 oil supply method
Q=WdB
Where Q - oil supply, mm3 / h
W——coefficient, 0.01mm/h
D——bearing inner diameter, mm
B——bearing width, mm
However, the actual oil supply should be expanded by 4 to 20 times based on this value. In order to obtain the best lubrication effect, it is necessary to experiment to correct the amount of oil supply.
4.2 Oil supply design
For high-speed rotating bearings, in order to reliably feed the lubricating oil into the bearing, the design of the oil supply method (such as nozzle form, installation position, etc.) should be taken very seriously. The way the bearings are lubricated depends entirely on the type and configuration of the bearings (Figure 4a). For single row bearings, the best way to lubricate is to enter the inside of the bearing from one side. The nozzle hole should be flush with the inner ring and should not point to the cage. Especially when the bearing's own suction and discharge direction is not easy to determine (such as angular contact ball bearings), the lubricant must enter the bearing inside in the above direction. If conditions permit, the lubricant preferably passes through a special nozzle before entering the bearing. The length of the nozzle depends on the size of the bearing and the diameter is 0.5 to 1.0 mm. It is also allowed to send the oil to the outer ring of the bearing (Fig. 4b). In this case, pay attention to see if the lubricant enters the pressure zone formed between the steel ball and the outer ring. For double row bearings, the lubricant must be sprayed into the bearing from the side of the outer ring raceway to adequately lubricate the bearings.
