Field of the Invention

[0001 ] The present invention relates to the monitoring of conveyor belt condition.

The invention has been devised for use in relation to ore-carrying conveyor belts, but is considered to have wider application.

Background to the Invention

[0002] In mining and mineral processing environments the carrying of ores by

conveyor belt is common place. As failure of a conveyor belt can potentially halt mining or processing operations, ongoing maintenance of conveyor belts is an important requirement.

[0003] In order for maintenance to be performed efficiently, it is necessary to

monitor the condition of the conveyor belts. In particular, it is important to monitor for surface irregularities such as cuts and grooves, as well as monitoring overall conveyor belt wear. Where cored conveyor belts (such as steel-cored belts) are in operation, it is necessary to measure both abrasive wear caused by the ore on an upper surface of the conveyor belt, and also under-side wear caused, for instance, by a seized idler roller. Measurement of wear on both upper and lower surfaces can reveal a propensity for the belt to be worn through to its core.

[0004] One common way of undertaking this monitoring in mining and mineral processing environments is by using a hand-held ultrasonic measuring tool. This tool passes an ultrasonic wave through a belt, where it can be reflected at either the steel core or at the other side of the belt, thus providing the tester with the belt thickness. This method, while effective at the point of measurement, is not suited to the detection of irregularities along the length of the belt. Significantly, too, this method requires the conveyor belt to be stopped, potentially causing operational downtime and loss of production.

[0005] It is considered desirable to arrange condition monitoring apparatus for a conveyor belt which can operate constantly, while the belt is in operation. This would obviate the problems noted above: it would monitor the entire belt length and would not require conveyor downtime. [0006] One such tool has been developed by American firm rEscan International. Known as a Textile Belt Analyser (TBA). This tool uses optical or radio waves to scan the belt surface as it passes. The tool is able to use this information to map the belt surface electronically.

[0007] The TBA tool is largely useless in dusty environments, such as in iron ore mining, as the optical/radio sensor is generally unable to distinguish between the conveyor material and the surrounding dust. In addition, the tool is arranged only to detect surface irregularities, and cannot provide appropriate information regarding belt wear.

[0008] Another tool used to monitor conveyor belt condition is the 'Belt Monitoring System (BMS)' produced by Australian company B&C Belting Solutions. The BMS system uses ultrasonic sensors to detect the edges of a conveyor belt, thus providing information regarding conveyor belt drift and monitoring changes in conveyor belt width. Although this tool can help identify wear occurring along the edges of the conveyor belt, it does not assist in identifying wear on the conveyor belt surface.

[0009] Searching of patent databases has revealed Korean patent number

KR100926527, which uses laser sensors to detect conveyor belt drift. The apparatus described can also be used to measure conveyor belt thickness, although it can only provide limited information regarding wear.

[0010] The present invention seeks to provide a way of continually monitoring

conveyor belt wear, and a suitable apparatus for incorporating this method.

Summary of the Invention

[001 1 ] According to one aspect of the present invention there is provided a method of monitoring wear on a cored conveyor belt, the method including the provision of a first sensor directed towards a face of the conveyor belt and a further sensor directed towards the core of the conveyor belt; the first and further sensors being parallel, the difference in position of the first and further sensors relative to a mutually parallel axis being known; measuring the distance from the first sensor to the face of the conveyor belt; measuring the distance from the further sensor to the core of the conveyor belt, and calculating the thickness of one side of the conveyor belt by adjusting the difference between the measured distances by the known value (if the further sensor is located on the same face of the belt as the first sensor) or by adjusting the sum of the measured values by the known value (if the further sensor is located on the opposite face of the belt to the first sensor). The calculation of thickness of one side of the conveyor belt may also incorporate an adjustment based on known properties of the conveyor belt core.

[0012] It is anticipated that the first and further sensors will be of different types. In a preferred embodiment of the invention the first sensor is an ultrasonic sensor and the further sensor is an eddy-current sensor. The present invention may be used to monitor wear on conveyor belts having a steel core.

[0013] According to a second aspect of the present invention there is provided a method of monitoring the thickness of a conveyor belt, the method including the provision of a first sensor directed towards a first face of the conveyor belt, and the provision of a second sensor directed towards a second face of the conveyor belt, the first and second sensors being substantially opposite each other and oriented towards each other, the distance between the first sensor and the second sensor being known; measuring the distance from the first sensor to the first face of the conveyor belt; measuring the distance from the second sensor to the second face of the conveyor belt; and calculating the thickness of the conveyor belt by subtracting the sum of the measured distances from the known distance.

[0014] It is preferred that the first and second sensor both be ultrasonic sensors.

[0015] It is preferred that the first and second aspects of the present invention be used concurrently; that is, that three sensors are used: a first sensor directed towards a first face, a second sensor directed towards a second face, and a further sensor directed towards the core. In this way three parameters can be determined: the overall thickness of the belt, the thickness of a working side (that is, the distance from conveyor belt core to the upper surface), and the thickness of an underside (that is, the distance from the conveyor belt core to the return surface).

[0016] In accordance with a third aspect of the present invention there is provided an apparatus for monitoring cored conveyor belt wear, the apparatus arranged to locate about a conveyor belt, the apparatus including a first sensor spaced from a first face of the conveyor belt, a second sensor spaced from a second face of the conveyor belt, and a further sensor spaced from the first face of the conveyor belt, wherein the first sensor is arranged to measure the distance between the first sensor and the first face of the conveyor belt, the second sensor is arranged to measure the distance between the second sensor and the second face of the conveyor belt, and the further sensor is arranged to measure the distance between the further sensor and a core of the conveyor belt. The conveyor belt may have a steel core.

[0017] It is preferred that the first and second sensors be ultrasonic sensors, and the further sensor be an eddy-current sensor.

[0018] It is further preferred that the apparatus includes a plurality of each of the first, second and further sensors, spaced along a width of the conveyor belt.

[0019] In some applications, wear on a conveyor belt can frequently occur at known locations. One such example is where a conveyor receives ore from a transfer feeder chute. Drift of the conveyor (i.e., lateral movement across rollers) can result in the edges of a skirt of the transfer feeder chute coming into contact with the belt and causing narrow grooves or slits oriented in the direction of travel.

[0020] The likely location of these grooves is determined by the geometry of the feeder chute skirt and the conveyor belt rollers.

[0021 ] Although the likely location of the grooves is known relative to the edges of the conveyor belt, the phenomenon of belt drift means that the location of the grooves relative to a fixed structure is not known. It is preferred that the apparatus of the present invention be positioned on the return run of the conveyor, and therefore measurement immediately after the transfer feeder chute is not practical.

[0022] In accordance with a fourth aspect of the present invention there is provided an apparatus for monitoring conveyor belt condition, the apparatus including at least one sensor directed towards a conveyor belt, the apparatus including mountings whereby the apparatus can be attached to a fixed structure, the mountings arranged to permit movement of the apparatus in at least one dimension, and the apparatus including guides arranged to position alongside opposed edges of the conveyor belt, such that the apparatus is able to locate in a known position relative to the lateral position of the conveyor belt.

[0023] It is preferred that the guides be formed from or coated in a low-friction

material, such as polytetrafluoroethylene.

Brief Description of the Drawings

[0024] It will be convenient to further describe the invention with reference to

preferred embodiments of the present invention. Other embodiments are possible, and consequently the particularity of the following discussion is not to be understood as superseding the generality of the preceding description of the invention. In the drawings:

[0025] Figure 1 is a perspective of a conveyor belt monitoring apparatus arranged about a conveyor belt;

[0026] Figure 2 is a cross-section through the conveyor belt monitoring apparatus of Figure 1 ;

[0027] Figure 3 is a side view of the conveyor belt monitoring apparatus of Figure 1 ;

[0028] Figure 4 is a perspective of the conveyor belt monitoring apparatus of Figure 1 ;

[0029] Figure 5 is a partially cut-away perspective of the conveyor belt monitoring apparatus of Figure 1 with protective covers removed;

[0030] Figure 6 is a schematic representation of a first sensor and a second sensor within the conveyor belt monitoring apparatus of Figure 1 ;

[0031 ] Figure 7 is a schematic representation of a first sensor and a further sensor within the conveyor belt monitoring apparatus of Figure 1 ; and

[0032] Figure 8 is a guide bracket from within the conveyor belt monitoring

apparatus of Figure 1 .

Detailed Description of Preferred Embodiments

[0033] Referring to the Figures, Figure 1 shows a portion of a conveyor belt 10

about which a conveyor belt monitoring apparatus 20 is positioned. The conveyor belt monitoring apparatus 20 is positioned on the return of the conveyor belt. The conveyor belt 10 has a first or top face 12, which is the underside of the belt on its working run, and second or bottom face 14, which is the working face. The conveyor includes a steel core 16. The conveyor belt has two side edges 18.

[0034] The conveyor belt monitoring apparatus 20 includes two scanning units 22, one positioned above the conveyor belt 10 and one below the conveyor belt 10. The conveyor belt monitoring apparatus 20 also includes two guide brackets 24, one mounted on each side edge 18 of the conveyor belt 10. The scanning units 22 are mounted at either side to the guide brackets 24, to form an effective loop around the conveyor belt 10.

[0035] The conveyor belt monitoring apparatus 20 is mounted to a fixed structure 26, which may be part of a conveyor belt supporting structure, by means of arms 28 which will be described in greater detail below.

[0036] The scanning units 22 can be seen in greater detail with reference to

Figures 4 and 5. Each scanning unit 22 has a leading roller 30 and a trailing roller 32, arranged to act as idler rollers for the conveyor belt 10. The scanning units 22 are positioned on the guide brackets 24 so that, in use, the conveyor belt 10 is in engagement with both rollers 30, 32 in both scanning units 22. The portion of the conveyor belt 10 between the leading roller 30 and the trailing roller 32 can thus be maintained in a taut, flat state.

[0037] The upper scanning unit 22 has a plurality of first sensors, being first

ultrasonic sensors 40, arrayed along the upper scanning unit 22 from one guide bracket 24 to the other guide bracket 24. The first ultrasonic sensors 40 are spaced, in use, from the conveyor belt 10, and are directed towards the top face 12 of the conveyor belt 10. The first ultrasonic sensors 40 detect the distance between each sensor 40 and the top face 12 of the conveyor belt 10.

[0038] The lower scanning unit 22 has an identical and corresponding array of

second sensors, being second ultrasonic sensors 42. These are similarly spaced from the conveyor belt 10, and are directed towards the bottom face 14 of the conveyor belt 10. The second ultrasonic sensors 42 detect the distance between each sensor 42 and the bottom face 14 of the conveyor belt.

[0039] The upper scanning unit 22 also has a plurality of further sensors, being

eddy-current sensors 44, spaced along the upper scanning unit 22 between the two guide brackets 24. The eddy-current sensors 44 are positioned, in use, close to the top face 12 of the conveyor belt 10, and are directed towards the top face 12 of the conveyor belt. The eddy-current sensors 44 detect the distance between each sensor 44 and the conveyor belt core 16.

[0040] In preparation for operation, each of the scanning units 22 is rigidly mounted to the guide brackets 24, so that the relative positions of the first ultrasonic sensors 40, the second ultrasonic sensors 42 and the eddy-current sensors 44 are all fixed and unmoving. The sensors 40, 42, 44 each have an axis of operation, and it will be understood that these axes are all parallel to each other, and perpendicular to a nominal plane representing an idealised conveyor belt surface. Measurements can then be taken to determine the distance from each sensor 40, 42, 44 to the nominal plane along its axis of operation.

[0041 ] Once these calibrating measurements have been taken, the sensors 40, 42, 44 can begin continuous operation as the conveyor belt 10 passes through the conveyor belt monitoring apparatus 20. In particular, the sensors 40, 42, 44 can measure the following parameters for any portion of the belt 10 passing them.

a. Total belt thickness is equal to the sum of the distances measured by a first ultrasonic sensor 40 and a corresponding second ultrasonic sensor 42, subtracted from the distance between the first ultrasonic sensor 40 and the second ultrasonic sensor 42 (as seen in Figure 6). b. Underside thickness is equal to the distance measured by the first ultrasonic sensor 40, subtracted from the sum of the distance between the first ultrasonic sensor 40 and an eddy-current sensor 44 and the distance measured by the eddy-current sensor 44 (as seen in Figure 7).

c. Working side thickness (as well as being equal to (a) minus (b), taking into account the thickness of the core) is equal to the sum of the distances measured by a second ultrasonic sensor 42 and an eddy- current sensor 44 and the known core thickness, subtracted from the distance between the second ultrasonic sensor 42 and the eddy- current sensor 44.

[0042] It will be appreciated that continuous measurement of these thicknesses across the belt surface as it travels through the conveyor belt monitoring apparatus 20 allows for a digital map of the entire conveyor belt 10 to be generated, showing any wear on the top surface 12 or the bottom surface 14.

[0043] Although this method is considered highly effective for determining wear, and for detecting transverse cuts or grooves, it is possible for thin grooves in the direction of travel, such as those caused by drift of the conveyor belt 10 near a skirt of a transfer feeder chute, to pass between adjacent pairs of ultrasonic sensors 40, 42 and therefore not be observed. As the likely location of such grooves on the belt surface can be easily determined, it is necessary to position ultrasonic sensors 40, 42 appropriately to monitor this location.

[0044] The guide brackets 24 and arms 28 of the conveyor belt monitoring

apparatus 20 act to fix the position of the scanning units 22 relative to the lateral position of the conveyor belt 10, rather than being fixed relative to the fixed location 26. In this way, in the event of conveyor belt drift, an ultrasonic sensor 40 remains positioned above the likely location of transfer feeder chute wear.

[0045] The guide brackets 24 has an inner projection 50, having a flat surface 52 arranged to abut an edge 18 of the conveyor belt 10. The flat surface 52 is coated in (or, indeed, the inner projection may be formed from) a low-friction material such as polytetrafluoroethylene (PTFE). The inner projection 50 is rounded at its ends to eliminate any prospect of snagging by the conveyor belt 10.

[0046] The arms 28 are jointed at either end so as to permit pivoting of the arms 28 relative to both the fixed location 26 and the guide brackets 24. The arms are also slightly extendible, for instance by use of a telescoping

arrangement, to allow for lateral movement of the scanning units 22 relative to the fixed location 26. In this way, the scanning units 22 track the lateral position of the conveyor belt 10. The conveyor belt monitoring apparatus 20 effectively rides or 'floats' over the conveyor belt 10 by this mechanism.

[0047] Safety chains 29 are provided alongside the arms 28 in order to hold the apparatus 20 in the event of failure of one of the arms 28.

[0048] Modifications and variations as would be apparent to a skilled addressee are deemed to be within the scope of the present invention.