Technical characteristics and application of bearing failure

1.Vibration diagnosis technology

As long as the working surface of the bearing element is subject to fatigue spalling, indentation or local corrosion, periodic pulse signals will appear during bearing operation. This periodic signal can be received by a sensor (speed or acceleration type) mounted on the bearing seat, and the fault of the bearing is diagnosed by analyzing the vibration signal.

Features: Vibration diagnosis technology is widely used; online monitoring can be realized; diagnosis is fast, and the diagnosis theory is mature.

Application: Particularly suitable for fault monitoring of bearings in rotating machinery.

2.ferrographic diagnostic technology

Bearing wear particles are closely related to their operating conditions. The lubricating oil with worn particles is passed through a strong magnetic field. Under the action of the strong magnetic field, the abrasive particles are deposited on the ferrograph sheet according to a certain rule. The ferrograph sheet can be qualitatively observed on a ferrographic microscope or tested on a quantitative instrument Based on this, judge the working condition of the bearing.

Features: The machine does not need to be disassembled; the investment is low and the effect is good; the early fatigue failure of the bearing can be found; the wear mechanism can be studied.

Application range: It is suitable for fault diagnosis of bearings lubricated with lubricating oil. It is more difficult for bearings lubricated with grease.

3. Oil film resistance diagnosis technology

Well-lubricated bearings have large resistance between the inner and outer rings due to the effect of the oil film. Therefore, by measuring the resistance of the inner and outer rings of the bearing, the abnormality of the bearing can be judged.

Features: The same evaluation standard can be used for different working conditions. The diagnosis of surface peeling, indentation, cracks and other abnormalities is poor.

Application: Suitable for occasions where the rotating shaft is exposed.

4.Optical fiber monitoring and diagnosis technology

Optical fiber monitoring is a diagnostic technique that extracts signals directly from the surface of the bearing ring. A displacement sensor made of an optical fiber bundle includes a transmitting fiber bundle and a receiving fiber bundle. The light is reflected back by the transmitting fiber bundle through the gap between the sensor end face and the bearing ferrule surface. It is received by the receiving fiber bundle and converted into an electrical signal by the photoelectric element. By analyzing and processing the electrical signal, the bearing condition can be evaluated.

Features: The optical fiber displacement sensor has high sensitivity; the signal is directly extracted from the bearing surface, which improves the signal-to-noise ratio; it can directly reflect the manufacturing quality, surface wear degree, load, lubrication and clearance of the rolling bearing.

Applications: Suitable for machines where the sensor can be mounted in a bearing housing.

5.Temperature diagnosis technology

If some abnormality occurs in the bearing, the temperature of the bearing will change. Therefore, according to the change in temperature, the fault of the bearing can be diagnosed, but the ability to judge abnormality is very low.

Features: simple diagnosis; better judgment of bearing burns.

Application: Simple and routine diagnosis of bearings in machines.

6, acoustic emission diagnostic technology

Metallic materials need to release elastic waves due to internal dislocations, grain boundary slippage, or the occurrence and development of internal cracks. This phenomenon is called acoustic emission. When the bearing is spalled or cracked, different types of acoustic emission signals are generated, which can be used to evaluate the condition of the bearing.

Features: fast and easy diagnosis; online monitoring.

Scope of application: New technologies developed in recent years have rarely been used in bearing condition monitoring.