Condition Monitoring of Slow Speed Rotating Machinery Using Acoustic Emission Technology

摘要

Slow speed rotating machines are the mainstay of several industrialapplications worldwide. They can be found in paper and steel mills,rotating biological contractors, wind turbines etc. Operational experience ofsuch machinery has not only revealed the early design problems but has alsopresented opportunities for further significant improvements in the technologyand economics of the machines. Slow speed rotating machinery maintenance,mostly related to bearings, shafts and gearbox problems, represents the causeof extended outages. Rotating machinery components such as gearboxes,shafts and bearings degrade slowly with operating time. Such a slowdegradation process can be identified if a robust on-line monitoring andpredictive maintenance technology is used to detect impending problems andallow repairs to be scheduled. To keep machines functioning at optimal levels,failure detection of such vital components is important as any mechanicaldegradation or wear, if is not impeded in time, will often progress to moreserious damage affecting the operational performance of the machine. Thisrequires far more costly repairs than simply replacing a part.Over the last few years there have been many developments in the use ofAcoustic Emission (AE) technology and its analysis for monitoring the conditionof rotating machinery whilst in operation, particularly on slow speed rotatingmachinery. Unlike conventional technologies such as thermography, oilanalysis, strain measurements and vibration, AE has been introduced due to itsincreased sensitivity in detecting the earliest stages of loss of mechanicalintegrity.This programme of research involves laboratory tests for monitoring slow speedrotating machinery components (shafts and bearings) using AE technology. Toimplement this objective, two test rigs have been designed to assess thecapability of AE as an effective tool for detection of incipient defects within lowspeed machine components (e.g. shafts and bearings). The focus of theexperimental work will be on the initiation and growth of natural defects. Further,this research work investigates the source characterizations of AE signalsassociated with such bearings whilst in operation. It is also hoped that at theend of this research program, a reliable on-line monitoring scheme used forslow speed rotating machinery components can be developed.