The shaft connecting bearing of automobile water pump is a bearing. The cage material is usually reinforced nylon 66, and the sealing ring material is usually Buna-N rubber. When the requirements are high, fluororubber sealing ring can also be selected.

The steel (including shaft, outer ring, steel ball roller) selected for conventional shaft coupling bearing is high carbon chromium bearing steel (GCr15). Because the smelting of high-quality bearing steel adopts vacuum deoxidation, electromagnetic stirring and less oxide content, it can withstand large contact compressive stress and high variable tensile stress. After heat treatment, the hardness of the raceway of the shaft is 58-62hrc. The hardness of the ring raceway is 60-64hrc, and the hardness of the steel ball and roller is 61-65hrc. When the shaft and outer ring are made of carburized bearing steel, the hardness of the raceway is 60-64hrc. The cage material is usually reinforced nylon 66, and the sealing ring material is usually Buna-N rubber. When the requirements are high, fluororubber sealing ring can also be selected.

Radial clearance

During manufacturing, the conventional axial bearing clearance is based on the radial clearance: under the condition of no special requirements and no load, the radial clearance is 15-35um. It is very important for users to reasonably select the fit interference between the outer ring and the sitting hole. Excessive interference will sharply reduce the radial clearance of the bearing, damage the bearing and make the water pump unable to work normally. In addition to the above reasons, in actual work, It is also necessary to consider that the thermal expansion caused by temperature rise reduces the clearance, so the recommended table of general interference is as follows:

OUTER D（mm）	INNER DEVIATION（um）
	IRON SHELL PUMP	ALUMINUM SHELL PUMP
30<	25-45	35-55
>30	32-55	55-76

 

Lubrication: since the water pump shaft connecting bearing works under the conditions of high speed and high temperature, the lubrication conditions directly affect the service life of the shaft connecting shaft. Generally, imported high-grade grease with high drip point and good consistency is adopted, and the radial contact seal with large interference is also adopted for the sealing ring to ensure that the bearing will not lose oil for a long time.

matters needing attention

Prevention of foreign matters during assembly

It is easy to balance the iron filings when they enter the bearing inlet? Therefore, it is best to do dynamic balance before installing imported bearings. Some manufacturers for assembly convenience? When assembling, apply some oil or grease to the inlet bearing chamber for lubrication effect? But it is often difficult for operators to control the quantity well? If more oil or grease is accumulated in the inlet bearing chamber? When the water pump shaft rotates with the inlet bearing, it is easy to enter the ina inlet bearing along the shaft. It is better not to apply oil or grease to the imported bearing chamber. If it is necessary to apply, it shall be controlled and there shall be no accumulation in the imported bearing chamber.

Prevention of paint rust

Paint rust is characterized by frequent occurrence in sealed motors? Does the motor sound well when assembled? But after some time in the warehouse? The abnormal noise of the motor becomes very large, and the shaft and inlet bearing of the water pump are seriously rusted. In the past, many manufacturers thought it was the problem of imported bearings? After our continuous publicity. The motor factory has realized that the main problem is the insulation paint. This problem is mainly because the acidic substances volatilized from insulating paint form corrosive substances under certain temperature and humidity? The ina inlet bearing is damaged after the inlet bearing channel is corroded. The problem can only be to select good insulating paint and assemble after drying and ventilation for a period of time. [3] 

Selection and control of tolerance of shaft and inlet bearing housing

The water pump shaft and the inlet bearing shall rotate flexibly without blocking feeling after being pressed into the inlet bearing. If there is obvious inflexibility of rotation? Is the size of the shaft too large? The tolerance should be lowered. If the water pump shaft and the inlet bearing are pressed into the shaft and rotated by hand, there is an obvious "rusty" feeling? It may be that the tolerance of the shaft is too large or the roundness of the shaft is not good. Therefore, when controlling the tolerance of shaft and imported bearing chamber, it is also necessary to control the roundness. Many domestic manufacturers only control the tolerance, not the roundness.