Rolling bearing “fever” is often encountered in production. If the cause analysis is not clear, the treatment is not timely, and the measures are not appropriate, it will often achieve half the result with twice the effort, and even cause bearing burning, reducer tooth beating and other malignant accidents.

1. Improper assembly method

The interference of bearing and shaft diameter or bearing seat hole is small, and the pressing method is used for assembly. The simplest method is to use a copper bar and a hand hammer to hit the seat ring of the bearing with interference fit symmetrically in a certain order, so that the bearing is pressed into smoothly. In addition, can also be made of soft metal sleeve by hand hammer or press into the press. If the operation is improper, the seat ring will be deformed and cracked, or the hand hammer will hit the non-interference fit seat ring, the raceway and rolling body will produce indentation or the bearing will be damaged indirectly.

2. Improper temperature control during assembly

When rolling bearings are assembled, if the interference between them and the shaft diameter is large, they are generally assembled by hot loading method. That is, the bearing is put into the oil drum containing oil, and the oil drum is heated externally with hot water or flame. The process requires that the oil temperature to be heated is controlled at 80 ° C to 90 ° C, generally not more than 100 ° C, and not more than 120 ° C at most. After heating, the bearing is quickly removed and fitted on the journal. If the heating temperature is too high due to improper temperature control, the bearing will be tempered and the hardness will be reduced, and the bearing will be easy to wear, spalling, temperature rise too fast or even cracking in operation.

It should be noted that when the bearing is “boiled” with oil, the bearing should be placed flat in the oil drum, and a height of about 50mm wood block or steel bar bracket should be placed between the bearing and the bottom of the cylinder, and the oil temperature should be controlled with an infrared thermometer or thermometer when heating. Because the oil bath heating method is not convenient for the measurement of bearing expansion, temperature control and installation, it is recommended to use electromagnetic induction heater.

3. Improper adjustment of bearing clearance during assembly

The clearance of rolling bearings is divided into radial clearance and axial clearance. Its function is to ensure the normal operation and lubrication of the rolling body and to compensate the thermal elongation.

For bearing clearance can be adjusted, because of its axial gap and radial gap there is a direct proportion relationship between, so the installation is adjust axial clearance can be obtained as long as the radial clearance, and they are usually in pairs used (i.e. in the ends of the shaft or end), as a result, only need to adjust a bearing axial clearance. But for the reducer, attention should be paid to tooth meshing when adjusting the bearing clearance. The axial clearance is generally adjusted with gaskets (compression wire method), and some can also be adjusted with screws or thrust rings. If the clearance adjustment is too large or the end cover of the reducer is loose during the operation, the bearing clearance is too large, which will not only cause the bearing itself big vibration, big noise, easy damage to the cage and other problems, but also further cause the misengagement of the tooth surface and cause the gear hitting accident of the reducer. For example, the gear hitting accident of the no. 2 kiln reducer of DY Company and the no. 1 kiln coal mill reducer of SS Company is mainly caused by the large axial clearance of bearing and the improper meshing of tooth surface.

For rolling bearing clearance shall not adjust, because of the radial clearance as defined by the standard in manufacturing has been good, can’t adjust, such loading on the diameter of axle bearing or bearing hole, after the actual radial clearance is called assembly radial clearance, assembly time to assemble the size of the radial clearance is right to make necessary work in the operation of radial clearance, to ensure that the flexible bearing rotation. When this kind of bearing is working, the relative displacement of the inner seat ring occurs because the shaft is heated and extended when the temperature rises, so that the radial clearance of the bearing is reduced, and even the rolling body is stuck between the inner and outer seat rings. The above phenomenon can be avoided if an axial clearance is left between a bearing in a double-supported rolling bearing (the other bearing is fixed on the shaft and in the bearing seat) and the side cover.

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