Monitoring of rolling bearings using magnetic plug method:
1. Requirements for monitoring rolling bearings using magnetic plugs
(1) Magnetic plugs are only suitable for monitoring critical main bearings lubricated with oil and returned through dedicated pipelines.
(2) The magnetic plug should be installed as close as possible to the monitored main bearing, on the main channel for oil return, without the obstruction of a filter screen, oil pump, or other hydraulic components in the middle.
(3) To improve monitoring efficiency, a rotary oil storage tank with return oil inlet and outlet can be made. The oil reservoir should be shaped into an inverted conical platform, and the magnetic plug should be installed at the bottom of the oil reservoir. The oil inlet of the oil reservoir should be tilted at a certain angle to allow lubricating oil to enter from the tangential direction. This is beneficial for the separation of wear particles from the rotating lubricating oil, and for settling at the bottom. It enters the magnetic plug through small holes and is adsorbed on the end of the magnetic steel.
2. Morphological characteristics of wear particles under normal conditions
During the running in period and normal operation period of rolling bearings, the size of abrasive fragments generated is generally 0.01-0.015mm, mixed with some metal powder. The number of abrasive fragments generated by the new bearing during the running in period is higher than that during the normal operation period. After entering the normal operation period, the number of abrasive fragments and metal powder will significantly decrease. The abrasive fragments present a thin and short shape under a microscope, with irregular cross-sections.
3. Morphological characteristics of faulty wear particles
The main failure form of rolling bearings is fatigue pitting. The size of abrasive fragments formed by rolling fatigue and peeling is generally 0.025-0.05mm. Sometimes there are larger fragments mixed with some metal powder. The steel ball abrasive fragments of ball bearings usually appear in the form of roughly circular, radially separated rose petals; The abrasive debris in the raceway presents a roughly circular surface fragmentation form; The grinding debris of roller bearings usually presents in a rectangular shape with a length equal to 2-3 times the width of the curl; The abrasive debris in the raceway generally presents an irregular rectangular shape.
Precautions for monitoring rolling bearings using temperature measurement method:
By measuring the temperature rise during bearing operation, it is generally difficult to monitor localized damage such as fatigue peeling, cracks, or indentations in rolling bearings, especially in the early stages of damage, where it is almost impossible to detect any problems. When the temperature of the bearing increases after long-term normal operation, the problem generally reflected is not only serious, but also rapidly developing, causing bearing damage and failure. At this point, intermittent monitoring often leads to missed monitoring. If the temperature of the bearing exceeds 70-80 ℃ during monitoring, it should be immediately stopped for inspection.
For newly installed or readjusted rolling bearings, the temperature rise can be monitored within the specified time using the temperature measurement method to determine the installation and adjustment quality of the bearings, especially when the clearance is too tight, there may be a phenomenon of excessive temperature rise. Timely adjustment when problems are discovered is beneficial for extending the service life of rolling bearings.