During the operation of the centrifugal fan, the normal operation of the main shaft is inseparable from the normal bearings, but in many cases, the failure of the main shaft of the fan is related to the bearing, especially in the case of high ambient temperature, the bearing failure caused by high temperature is caused by The main reason for the damage of the fan main shaft, what is the reason for the high temperature of the centrifugal fan bearing?
1)The reason why the bearing temperature of centrifugal fan is too high
1. Installation error: The bearings at both ends of the main shaft of the fan are not installed concentrically or due to the installation and positioning error of the main shaft, the gap between the end cover of the non-positioning end bearing seat and the outer ring of the bearing is too small. After the main shaft is heated and expanded, the bearing The friction between the outer ring and the end cover will cause the bearing to heat up.
2. Insufficient or excessive amount of lubricating oil: Centrifugal fans are mostly lubricated by circulating oil. The oil pressure and oil temperature of the lubricating station have a great influence on the bearing seat temperature. It is difficult to obtain effective lubrication, and the frictional force increases to generate heat.
3. Serious bearing wear: After a long time of use, the fan bearing will inevitably wear to a certain extent. If the wear is serious, the axial and radial clearances will be too large, resulting in excessive friction, or Excessive heat generation due to unbalanced operation.
4. The ambient temperature is too high: The bearing seat temperature of the centrifugal fan fluctuates greatly with the ambient temperature, and the instability of the process operation leads to unstable air temperature, which affects the bearing seat temperature.
Regarding the reason for the high temperature of the centrifugal fan bearing, in addition to the above points, the lubricating grease is added in accordance with the standard, or the bearing seat casting defect, bearing seat Kabang, etc. will also cause the bearing temperature to be too high, which needs to be carried out in strict accordance with the standard. For the production, installation and maintenance of fan components, see below for specific treatment methods.
2)the treatment method of centrifugal fan bearing temperature is too high
1. Calibration error: Standardize maintenance procedures, check on site by spot inspectors, strictly implement maintenance standards for installing centrifugal fans, and control quality. Centrifugal fan manufacturers perform concentricity calibration of bearing housing bores.
2. Reduce bearing seat clamps: Put a certain thickness of copper sheet between the upper and lower middle planes of the bearing seat, the thickness is generally between 0.05-0.2mm, and continue to adjust until the bearing runs Flexible, until the fever is normal.
4. Regular maintenance: It can be judged by measuring the vibration trend and sound of the fan every day, and formulate a scientific and reasonable bearing maintenance and replacement cycle according to the trend.
5. Cleaning the bearing seat: During the casting process of the bearing seat, the internal water cavity is small, which reduces the cooling strength. Generally, this situation rarely occurs, but once this is the reason, the bearing seat must be scrapped . If the water cavity of the bearing seat is blocked, remove the bearing seat and use a pickling pump to flush the water cavity of the bearing seat.
It is not difficult to see that in order to reduce the bearing temperature of the centrifugal fan, in addition to eliminating some production and installation defects, the cooling method is mainly used to achieve the purpose of cooling the bearing, and the cooling of the bearing is mostly lubricating oil. The bearing cooling method, I hope to be helpful to everyone.
3) Centrifugal fan bearing cooling method
1. Air-cooling the bearing housing
The cooling fan is an important cooling device for the centrifugal fan. Its function is to transport the cold air from the outside to the bearing box inside the casing through the holes at the bottom of the casing for cooling. After heat exchange, it is discharged from the holes in the upper part of the casing. The cooling effect of the cooling fan has a very important relationship not only with the ambient temperature in the fan room, but also with the cooling fan itself. Increasing the cooling air volume of the cooling fan is an important means to control the bearing temperature, and the maintenance and installation of the cooling fan is also critical. During the rotor installation process of the cooling fan, improper coordination between the collector and the rotor inlet is also the main reason for the low cooling air volume and air pressure.
2. Cool the lubricating oil
The oil cooler of the control oil station is the cooling source of the lubricating oil entering the bearing box, so it is also an important part to control the bearing temperature. The cooling effect of the oil cooler mainly depends on the temperature of the cooling water, the cooling area of the oil cooler and whether the oil cooler is blocked. When the cooling area and the cooling water temperature are constant, the cooling effect is mainly determined by measuring the temperature of the inlet and outlet of the oil cooler. The larger the difference is, the better the cooling effect is. Generally, it should be around 10°C, otherwise the cooling oil should be cleaned in time. device. However, when the lubricating oil temperature is closer to the cooling water temperature, the cooling effect is less obvious, which is mainly reflected in the start-up process of the unit. Replacing the oil cooler with a large cooling area is an important means to reduce the bearing temperature.
3. Use the temperature controller to adjust the lubricating oil temperature
The temperature controller that controls the oil station is a component that adjusts the temperature of the lubricating oil entering the bearing box. Its working principle: when the unit just starts the centrifugal fan to rotate, the oil temperature of the lubricating oil is low, and the spring in the temperature controller has a large elasticity. Lift the slide valve, the lubricating oil enters the bearing box directly from the outlet pipeline in the middle of the temperature controller, and the oil cooler is in a short-circuit state; The spring in the temperature controller becomes less elastic due to the increase in temperature. The slide valve moves downward under the action of the lubricating oil pressure of the upper oil inlet, blocking the middle outlet. At this time, all the lubricating oil enters from the lower outlet of the thermostat. After cooling in the oil cooler, it enters the bearing housing to achieve the purpose of cooling.