Underground » Maintenance
Idler bearing failure on underground conveyors is a significant problem in the Coal Industry. Trunk conveyors in underground coal mines have around 5000 idler bearings per kilometre. With a normal life of about 5 years, this can lead to as many as 10 failures per kilometre per day. The present practice is for damaged idlers to be hopefully identified by inspectors walking the belt. If the failing idlers are not detected and replaced promptly there is a serious risk of belt damage and fire risk due to seized idlers. If they are changed early, idler replacement costs increase.
VIPAC Engineers & Scientists Ltd. responded to the need for rapid Idler Condition Monitoring by developing in 1989, a vehicle mounted Bearing Acoustic Monitor (BAM) for surface conveyors.
Since the BAM system was delivered, VIPAC has been continuing the development of this technology, and trialing its applicability to various applications including rail and haul-truck wheel bearings.
VIPAC's effort in this area culminated in the development in 1996, of a prototype portable Acoustic Bearing Fault Detection Unit for underground conveyors with funding from ACARP, under ACARP Project C4019.
During ACARP Project C4019, a lightweight, hand-held prototype Acoustic Bearing Fault Monitor that relies mainly on digital signal processing was designed, built and tested. The instrument was proved to be capable of:
- remote detection of bearing faults from a distance of up to 1m.
- detection of build-up on rollers
- screening out extraneous noise
- ranking the severity of detected faults to provide an early notice of bearing damage
The objectives of the current project C5020 were to carry out the final product development phases, including Intrinsic Safety, to develop the prototype unit into a commercially viable instrument.
In view of the difficulties and uncertainties associated with IS (Intrinsic Safety) issues, the approach adopted by VIPAC and ACR was to release two versions of the instrument, a non-IS version first followed by an IS version thereafter. The advantage of this is two-fold; a) to minimise uncertainties on the release date for the product; and b) mines can purchase a non-IS version for use in non-hazardous areas at reduced cost.
The development of the non-IS version has now been completed successfully and the instrument has been successfully trialed at BHP's Tower Colliery.
Work is now focused on the IS version. As the design strategy adopted favoured a product which would offer minimal differences between the two versions, from the beginning of the project, IS issues have already been addressed. We therefore do not anticipate any major difficulties during the development of the IS version.