The fault diagnosis technology of needle bearing mainly includes vibration diagnosis technology,iron spectrum diagnosis technology, temperature diagnosis technology, acoustic diagnosis technology, oil film resistance diagnosis technology and optical fiber monitoring diagnosis technology, among which vibration, iron shop and temperature diagnosis technology are widely used.
1. Vibration diagnosis technology
When fatigue spalling,indentation or local corrosion occurs on the working surface of the needle roller bearing element, periodic pulse signals will appear during the running of the needle roller bearing. The periodic signal can be received by a sensor(velocity type or acceleration type) mounted on the bearing seat, and the fault of the needle roller bearing can be diagnosed by analyzing the vibration signal.
Features: vibration diagnosis technology is widely used; On-line monitoring can be achieved;Diagnosis is quick, diagnosis theory is mature.
Application range:especially suitable for fault monitoring of needle bearings in rotary machines.
2. Iron spectrum diagnosis technology
Wear particles of needle roller bearings are closely related to their working conditions. Through a strong magnetic field, the lubricating oil with wear particles will be deposited on the iron plate according to a certain rule under the action of a strong magnetic field. The iron plate can be qualitatively observed on theferrography microscope or tested on the quantitative instrument to determine the working status of the needle roller bearing.
Features: no disassembly of the machine; Low investment and good effect; Early fatigue failure of needle roller bearing can be found. The mechanism of wear can be studied.
Application range: it is suitable for fault diagnosis of needle roller bearing lubricated with lubricating oil.
3. Oil film resistance diagnosis technology
Well-lubricated needle roller bearings, due to the oil film role, between the inner and outer ring of large resistance. Therefore, by measuring the resistance of the inner and outer ring of the needle roller bearing, the abnormality of the needle roller bearing can be judged.
Features: the same evaluation criteria can be used for different operating conditions. The diagnosis of surface peeling, indentation and crack is poor.
Scope of application:suitable for applications where rotating shaft is exposed.