The fault diagnosistechnology of needle bearing mainly includes vibration diagnosis technology,iron spectrum diagnosis technology, temperature diagnosis technology, acousticdiagnosis technology, oil film resistance diagnosis technology and opticalfiber monitoring diagnosis technology, among which vibration, iron shop and temperaturediagnosis technology are widely used.
1. Vibration diagnosistechnology
When fatigue spalling,indentation or local corrosion occurs on the working surface of the needleroller bearing element, periodic pulse signals will appear during the runningof 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 faultof the needle roller bearing can be diagnosed by analyzing the vibrationsignal.
Features: vibrationdiagnosis 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 spectrumdiagnosis technology
Wear particles ofneedle roller bearings are closely related to their working conditions. Througha strong magnetic field, the lubricating oil with wear particles will bedeposited on the iron plate according to a certain rule under the action of astrong magnetic field. The iron plate can be qualitatively observed on theferrography microscope or tested on the quantitative instrument to determinethe working status of the needle roller bearing.
Features: nodisassembly of the machine; Low investment and good effect; Early fatiguefailure of needle roller bearing can be found. The mechanism of wear can bestudied.
Application range: itis suitable for fault diagnosis of needle roller bearing lubricated withlubricating oil.
3. Oil film resistancediagnosis technology
Well-lubricated needleroller bearings, due to the oil film role, between the inner and outer ring oflarge resistance. Therefore, by measuring the resistance of the inner and outerring of the needle roller bearing, the abnormality of the needle roller bearingcan be judged.
Features: the sameevaluation criteria can be used for different operating conditions. Thediagnosis of surface peeling, indentation and crack is poor.
Scope of application:suitable for applications where rotating shaft is exposed.