【文章內(nèi)容簡介】 costs. In order to optimise maintenance efforts, the concept of intelligent maintenance is introduced. The powered maintenance trolley that can travel autonomously over the structure of a belt conveyor is adapted as a platform of the maintenance system. On this trolley, data acquisition equipment for vibration analysis is installed. Data mining can be done either on board of the trolley or in a central puter depending on the maintenance strategy. The optimum maintenance strategy is determined by a logistic simulation model that accounts for the layout of the belt conveyor itself and the accuracy of the information on the remaining lifetime of its ponents. INTRODUCTION Today more and more panies outsource maintenance in an attempt to balance the budget and reduce the number of permanent staff members. Outsourcing maintenance however only works if the pany that takes over maintenance employs welltrained and experienced personnel that stays on a specific job for a considerable time. Unfortunately, reality is different and many panies have poor experiences with external panies performing maintenance. In general, maintenance on belt conveyor systems can be divided into inspection or condition monitoring of the total system and replacement and/or reparation (in short servicing) of its ponents. Most problems experienced with outsourcement of maintenance are associated with the inspection or condition monitoring of a system. It is not trivial to access the status of sometimes moving ponents of a belt conveyor. The same experienced person should therefore carry out inspections on a regular basis. To overe operational problems caused by a lack of experience of external maintenance personnel, the inspection of belt conveyor ponents can be automated. In this way knowledge of for example wear rates and replacement schedules can be built up in a data base system. The external maintenance crew then can be used to replace the worn off ponents. Alternatively, replacement of ponents can be automated as well. This paper discusses strategies and techniques for automated maintenance of belt conveyor systems. Section 2 defines the concept of intelligent maintenance, Section 3 discusses existing inspection systems that can be used in automated maintenance systems. Section 4 discusses means of assessing the status of rotating ponents of belt conveyors based on vibration based monitoring concepts. Section 5 presents a case study and section 6 finally lists the conclusions and remendations. INTELLIGENT MAINTENANCE Maintenance on belt conveyor systems can be divided in condition monitoring of the total system and servicing of its ponents. Condition monitoring is defined as the continuous or periodic measurement and interpretation of data to indicate the condition of a ponent to determine the need for replacement or servicing. Condition monitoring therefore deals with the acquirement of data (data acquisition or DAQ) from sensors, the interpretation of that data (data mining or DAM) and with taking corrective actions (ACT) on ponents that are to fail, thus preventing fail systems from developing and propagating. The basic concept of condition monitoring is to identify subtle changes in operation, such as increased vibration levels, that indicate a mechanical (or electrical) problem is starting to develop. These early messages provide more time to plan for machine downtime and repair. There are four typical types of maintenance: ? preventive maintenance: calendar based, . activities are planned depending on working hours or at certain time intervals (scheduled maintenance)。 it may be based on observed deterioration of ponents。 nothing is repaired but preventive jobs are done. ? random maintenance: opportunity based, . maintenance is done when the opportunity arises。 the decision to maintain a ponent based on opportunities may or may not be triggered by the condition of a ponent. ? corrective maintenance: emergency based, . repairing when a ponent malfunctions。 this may cause a general shutdown of the system。 the repair activity was not scheduled beforehand. ? predictive maintenance: condition based, . ponents are being monitored and when irregular factors are discovered, one waits until a maintenance opportunity arises。 it is a planned and corrective maintenance. From the above given four types of maintenance it is clear that only a predictive maintenance concept qualifies for application in an intelligent maintenance system that enables maintenance automation. Intelligence here is defined as the ability to make decisions based on information gathered through sensors in the equipment or provided by the control system of the total transport system. Applied to belt conveyor systems the information gathered from a system is information on the life expectancy of individual ponents as for example idler rolls. This information leads to a decision either to inspect a certain idler station and its rolls more frequently or to change a roll for a new roll. Repairing in fact here means changing one roll for another. Whether or not a roll can be repaired and the effect of that on the belt conveyor’s performance is outside the scope of this study. The main issue in this study is the question how an automated inspection strategy is affected by the accuracy of the data acquired. In theory there are two outer limits in predictive maintenance. The first is that no accurate information of the rolls is available at all, basically meaning that an assessment of the remaining lifetime is made purely on the basis of historical data provided by the roll or bearing manufacturers (predictive maintenance based on statistics). The second is that during inspection very accurate information on the status of rolls is generated enabling an accurate assessment of the remaining lifetime of an individu