Classification of Rolling Bearing Fault Diagnosis Technology
Rolling bearing is an important component of precision machinery and equipment. Due to its operating environment and complex working conditions, faults often occur. Therefore, the application of bearing fault diagnosis technology has become a research hotspot in the field of machinery and equipment condition monitoring. It is of great significance for reducing maintenance costs, improving production efficiency and improving equipment reliability to accurately diagnose and locate bearing faults as soon as possible.
Generally speaking, bearing fault diagnosis can be divided into two categories: non-destructive testing and destructive testing. Non-destructive testing includes acoustic emission testing, vibration testing, ultrasound testing and magnetic testing. Destructive testing includes chemical analysis, microscopic inspection and electric leakage direct current resistance testing.
1. Acoustic Emission Testing
This method is based on the fact that the bearing produces sound when a fault occurs and the frequency of the sound changes with different faults. Acoustic emission testing is a non-destructive testing method. By measuring the bearings acoustic emission signals or acoustic emission pulse frequency, the bearings inner defects can be determined. Acoustic emission testing method has the advantages that the instrumentation is light, the testing speed is fast, the instrument is easy to use, and the test personnel need only preliminary training.
2. Vibration Testing
This method is based on the fact that when the rolling bearing has an internal fault, the vibration waveforms of various vibration transmission components that form a complete loop in the rotating machinery change. Vibration testing is used to measure the vibration characteristics of the bearing and analyze the frequency spectrum and waveform of the vibration signals. By comparing the measurement results with the database of fault classification, it can be inferred whether the bearing has an internal fault. Vibration testing is a common bearing fault diagnosis technology with relatively mature technology.
3. Ultrasound Testing
This method is inspired by the fact that when a bearing fault occurs, due to the friction between the Fault caused by the surface and the ball, The ultrasonic waves of different frequency and amplitude are emitted. Ultrasound testing methods are mainly divided into three types, namely pitch-catch, pulse-echo, and scanning. Compared with vibration testing, it has the advantages of strong directivity, good resolution and applicability, especially its good fault diagnosis capability in the early stage of fault.
4. Magnetic Testing
This method is mainly based on the fact that when a rolling bearing fault occurs, strong magnetic fields will be generated at the fault part, and the measurer can measure the distributed characteristic of the magnet field and analyze the magnetic field distribution characteristics. This method is a non-destructive testing method with good sensitivity, but because of its complex operation, the information obtained by the method is not accurate enough.
5. Chemical Analysis
This is a destructive test method, which is mainly to detect the wear and staining of debris debris which is removed from the fault part to detect the size and material of the wear debris. It is mainly used to diagnose the causes of bearing fatigue failure and judge whether it is confused by foreign objects.
6. Microscopic Inspection Testing
This is also a destructive test method, mainly to detect whether the surface of the bearing parts is seriously worn, scratched and whether the phenomenon of mating surface burn occurs. The macroscopic and microscopic structure of the bearing parts is magnified by the optical microscope, and the fatigue failure mode of the bearing parts is observed and determined.
7. Electric Leakage Direct Current Resistance Testing
This test method takes the surface leakage current of the bearing as the target of detection. Mainly using the galvanometer to detect the leakage current of the bearing roller and cage, to test if there is a local increase and decrease of the surface leakage current of the bearing parts, and then judge the degree of abrasion and slip of the bearing parts.
Through the above introduction, we can see that the application of rolling bearing fault diagnosis technology has a vital importance. It is necessary to choose suitable testing methods according to actual conditions when diagnosing bearing faults, so as to avoid the premature handling of the fault.
