The fault diagnosis technology of rolling bearing mainly includes vibration diagnosis technique, ferrograph diagnosis technique, temperature diagnosis technique, acoustic diagnosis technique, oil film resistance diagnosis technique and optical fiber monitoring diagnosis technique, etc. Among them, vibration, iron paving and temperature diagnosis techniques are the most commonly used.
1. Vibration diagnosis technology
When the working surface of the bearing component has fatigue peeling, indentation or local corrosion, periodic pulse signals will appear during the operation of the bearing. This periodic signal can be received by a sensor (velocity type or acceleration type) installed on the bearing seat, and the fault of the bearing can be diagnosed through the analysis of the vibration signal.
Features: Vibration diagnosis technology is widely used; online monitoring can be realized; diagnosis is fast, and diagnosis theory is mature.
Application range: Especially suitable for fault monitoring of bearings in rotating machinery.
2. Ferrograph diagnostic technology
Bearing wear particles are closely related to their working conditions. Pass the lubricating oil with abrasive particles through a strong magnetic field. Under the action of the strong magnetic field, the abrasive particles are deposited on the ferrograph according to a certain rule. The ferrograph can be qualitatively observed on a ferrograph microscope or tested on a quantitative instrument , Based on this to judge the working condition of the bearing. SKF 24056 CC/W33 bearings are online , if you are interested , pls click here :
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: Suitable for fault diagnosis of bearings lubricated with lubricating oil, but difficult for bearings lubricated with grease.
3. Oil film resistance diagnosis technology
A well-lubricated bearing has a large resistance between the inner and outer rings due to the action of the oil film. Therefore, the abnormality of the bearing can be judged by measuring the resistance of the inner and outer rings of the bearing.
Features: The same criteria can be used for different working conditions. Diagnosis of abnormalities such as surface peeling, indentation, and cracking 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. The displacement sensor made of optical fiber bundles includes a transmitting fiber bundle and a receiving fiber bundle. The light is reflected by the transmitting fiber bundle through the gap between the sensor end face and the bearing ring surface, received by the receiving fiber bundle, and converted into electrical signals by photoelectric elements. Through the analysis and processing of the electrical signals, the bearing operating conditions can be evaluated.
Features: The optical fiber displacement sensor has high sensitivity; the signal is extracted directly from the bearing surface, which improves the signal-to-noise ratio; it can directly reflect the manufacturing quality, surface wear, load, lubrication and clearance of the rolling bearing.
Application: Suitable for machines where the sensor can be installed in the bearing housing.
5. Temperature diagnosis technology
If some kind of abnormality occurs in the bearing, the temperature of the bearing will change. Therefore, according to temperature changes, bearing faults can be diagnosed, but the ability to judge abnormalities is very low.
Features: Simple diagnosis; better judgment of bearing burn.
Application: Suitable for simple routine diagnosis of bearings in machines.
6. Acoustic emission diagnostic technology
Metal materials need to release elastic waves due to internal lattice dislocations, grain boundary slippage, or due to the occurrence and development of internal cracks. This phenomenon is called acoustic emission. When the rolling bearing is peeled or cracked, different types of acoustic emission signals will be generated, which can be used to evaluate the bearing conditions.
Features: fast and easy diagnosis; online monitoring.
Application scope: New technologies developed in recent years are rarely used in bearing condition monitoring.