R.E.M. Koenis
Simulatie onderhoudsrobot voor een bandtransporteur.
Computer program,
Report 2002.LT.5668, Transport Engineering and Logistics.
A strategy for a maintenance robot for a conveyor belt has been drawn up by
K.H. Wallien ("Onderhoudsstrategie van een onderhoudsrobot voor
bandtransporteurs", report 2002.LT.5602 (in Dutch)).
This strategy explains how the maintenance robot (BOR) has to inspect and if
necessary replace rolls in a conveyor. The strategy has two possibilities
of how to inspect the rolls:
- The inspection is more frequent when the roll gets to the end of its
lifetime. (Flex)
- There is a continuous inspection, regardless of the condition of the
bearing. (Fixed)
Furthermore, there are three different plans for the maintenance robot to
carry out the inspection and replacement activities:
- The maintenance robot carries out the inspection and the replacement
activities on the outward journey, and has no activity on the inward
journey. (I+OèXç)
- The maintenance robot carries out the inspection and the replacement
activities on the outward journey and on the inward journey.
(I+Oçè)
- The maintenance robot carries out the inspection on the outward journey
and the replacement activities on the inward journey.
(IèOç)
The combination between two inspection strategies and three inspection and
replacement strategies gives a total of six possibilities. To determine
which of these possibilities is the best, a program has been developed that
simulates these six situations. During the development of the program, the
proposed strategies have been maintained.
The program uses a graphic interface. In this interface the variables for
the actual simulation can be modified. Since the minimum and maximum lifespan
of the bearings and the relation in-between is not yet known, it is not
possible to make an accurate simulation.
It is possible after the simulation to make a comparison between the different
inspection and movement plans. This gives some interesting results. The
assessment of these results is given in table SE.1. Extra care has to be taken
when comparing the assessment of the broken bearings with the assessment of the
cycle time, because the costs for the BOR are unknown. It might be better to
let the BOR make extra movements or to replace bearings.
Table SE.1: Assessment of the performance of the plans in the simulation
Inspection plan
| No broken bearings
| Cycle time |
| #days to early
| length VT
| length BT
| #cycles
| #length
|
| Flex (I+OèXç)
| +/-
| +/-
| +
| +
| +
|
| Flex (I+Oçè)
| -
| -
| +
| +
| +
|
| Flex (IèOç)
| -
| -
| +
| +
| +
|
| Fixed (I+OèXç)
| +
| +
| NA
| -
| +
|
| Fixed (I+Oçè)
| +/-
| +/-
| NA
| -
| +
|
| Fixed (IèOç)
| +
| +/-
| NA
| -
| +
|
The first conclusion that can be drawn, is the proposed times for the start
time of the inspection and the replacement in the maintenance strategy by
Wallien can not be maintained if the goal is that there shouldn't be any rolls
replaced after they brake down. Therefore, there is a possibility in the
program to specify the start time of the inspection and the replacement time
separately.
Secondly, it seems that there is a decrease in the number of movements when
inspection plan Flex is used. If it is not desirable to have the robot active
all day, then inspection plan Flex has an advantage over inspection plan Fixed.
The third conclusion that can be drawn is that the rolls replaced in movement
scheme Fixed are replaced later than in scheme Flex. The average number of
days until the rolls brake down is lower. This means that the rolls last
longer and a cost reduction can be realized.
It is shown in table SE.1 that
Flex (I+OèXç)
and
Fixed (I+OèXç)
are the two plans working well. Therefore it will depend on the costs of the
BOR which plan will work best.
Reports on Transport Engineering and Logistics (in Dutch)
Modified: 2004.06.20;
logistics@3mE.tudelft.nl
, TU Delft
/ 3mE
/ TT
/ LT.