AU2016202263B2 - Belt wear profile measurement - Google Patents

Abstract

An apparatus and associated method is disclosed for assessing remaining carry cover thickness of a steel cord conveyor belt (1) without interrupting normal operations. The apparatus is positioned adjacent to a tail pulley (2) at an unloaded point. The apparatus uses ultrasonic or inductive sensors (9) for measuring remaining cover thickness as claimed in Australian Patent Application No. 2012 216 769. The sensors (9) are mounted on a carriage (7) that is driven along a linear slide (3) by a servo motor (16), and scan in a direction transverse to the operating belt (1), the scan sweeping out a zig-zag path along the belt due to lateral belt wander and longitudinal motion. The carriage (7) is controlled by a microprocessor (20), which receives and records signals from the remaining cover thickness sensors (9), a carriage absolute displacement sensor (14), a belt lateral position indicator (21), a belt speed tachometer (22), a splice detector (23), and a belt section RFID reader (35). The recorded signals are analysed to correlate sensor readings with lateral and longitudinal positions on the belt (1) and its constituent belt sections. Related readings are then averaged into representative profiles of remaining cover thickness, and used, inter alia, for forecasting serviceable belt life. 5004N-AU 2110 LON 0 c Luu oc (0 0 L LUU Q Q' C/) -LL. Q ~ 0 I Q)Q

Description

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Field of the Invention The present invention relates to conveyor belts and, in particular, to conveyor belts having rubber covers either side of steel reinforcing cords. Such steel reinforced conveyor belts are widely used in bulk materials handling.

Background Art The traditional conveyor belt consists of a fabric tension member covered with top and bottom elastomeric covers. It is known that this type of belting stretches and is unsuitable for applications involving long conveyor flight lengths, significant lift and high tonnage product throughput. In these applications, the stretch in the belting renders it incapable of being driven by the drive pulley(s), through lack of grip.

To overcome this problem, a type of belting was devised which uses a multitude of high tensile longitudinal steel ropes or cords as the tension member. The cords have low elongation and facilitate much higher tension applications.

Above and below the tension member is bonded the elastomeric belt "covers". These two covers are commonly referred to as the Carry (or Top or Dirty) Cover and the Pulley (or Bottom) cover respectively. The material being conveyed sits on the carry cover in the conveyor "carry run" and the belting is driven through its pulley cover via its drive pulley(s).

The thickness of the covers and their elastomeric characteristics are defined at the time of fabrication. The thickness of both carry and pulley covers in a new belt is specified after careful consideration of the anticipated duty of the specific belting.

It is natural for the covers to "wear" during use, that is to say, be reduced from the manufactured thickness to some lesser value, via various agencies, but the rate of wear can vary greatly from one conveyor to another conveyor, depending on the type of usage. The cycle time of the conveyor, and the abrasive nature of the

5004N-AU conveyed product, together with its lump size and density are typical drivers of the rates of wear.

In certain applications, total loss of cover, in a particular belt area, can determine the end-of-life of a conveyor belt. For this reason, in these applications, it is critical to know what the "remaining cover thickness" value is at any time in the life of the conveyor belt. With this knowledge it is possible to predict the end-of-life horizon for a particular belt and plan and/or budget accordingly for its replacement.

This measurement requirement is well recognized and a number of measurement regimes have been created to quantify the value.

Current prior art practice sees static cover thickness measurements made using hand-held magnetic or ultrasonic probes. The probes are applied to the cover's surface, with the belt stopped, which state is undesirable due to the down time, and the resulting values manually logged for a number of locations across the belt width.

This technique is satisfactory for determining the cover thickness at a nominated location along a belt section and also for establishing the shape of the lateral wear profile. However, it is inadmissible for accurately determining the expected end-of life date in a cover because the measurement is made at a randomly selected location along the belting and not necessarily at the point of minimum cover thickness (which is not visible or otherwise known).

It is typical to see variations in finite cover thickness throughout a belt section following manufacture. This results from the manufacturing process and the tolerances applied to the raw rubber cover stock etc. For this reason it is essential that a set of cover thickness measurements be made at the points of minimum cover thickness for any belt section.

In hard rock mining, in particular, such steel reinforced conveyor belts have a relatively short life compared, for example, with the operating life where such belts are used to transport coal. The reason for this is that hard rock materials such as iron ore, copper ore and bauxite are particularly dense and abrasive and thus the carry

5004N-AU cover of the belt is worn in use. However, it is virtually impossible for the carry cover of a belt to wear uniformly across the full belt width. Certain lateral locations may not wear at all since typically the extreme outer edge or side regions of the belt never carry any product or load. Typically covers that do wear take on a characteristic transverse "wear profile" depending upon the nature of their duty.

It is very desirable for operational and budgetary reasons to be able to effectively predict when a steel reinforced conveyor belt will reach the end of its operational life.

Genesis of the Invention The Genesis of the present invention is a desire to increase the accuracy of such predictions.

For many conveyor belts, the belt is used in the same way day in and day out and thus the rate of wear, and the location of the maximum wear, is substantially predictable. However, particularly in port facilities, many conveyor belts are used in different ways on different occasions. This may involve blending of different materials, loading materials from different sources to different destinations, using multiple load points on the same conveyor which necessitates side loading and other complex loading geometries, and the like. Under these circumstances, a hypothesis upon which the present invention is to some extent founded, is that the rate of wear and the location of the maximum wear are not fixed but can vary. As a consequence, the prediction of expected belt life under these circumstances is much more complicated.

For many years attempts have been made to measure various conveyor belt parameters. These measurement activities can be divided into two distinct groups. The first group requires that the belt be stopped in order for the measurement to take place. This is highly undesirable since most belts run 24 hours per day, 7 days a week, apart from scheduled maintenance shutdowns of short duration and all downtime represents a significant financial loss to the belt operator. The second group enables measurements to be taken whilst the belt is in normal operation and such measurements are infinitely more desirable than those of the first group.

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Prior art first group measurements involve manual measurement of the belt cover thickness, for example, which is the distance between the surface of the cover and the upper surface of the steel reinforcing cords. These measurements are done manually using hand-held instruments.

Prior art second group measurements involve directing a laser or ultrasonic probe at the unloaded surface of the cover as the belt passes over an idler roller or pulley. This measurement measures the overall thickness of the belt. Such measurements do not measure the remaining thickness of the cover which is the distance between the upper surface of the cover and the upper surface of the steel reinforcing cords.

Just recently a measurement technique which enables the remaining cover thickness of the carry or "working" cover, for example, to be measured at a given lateral location, with the belt running, has been discovered. This measurement technique is described in Australian Patent Application No 2012 216 769 the substantive contents of which are incorporated by a prosecution amendment into the present specification for all purposes. The applicant in respect of the above-mentioned patent applicant is also the applicant of the present application. As at the priority date of this application, there have been no sales of the apparatus disclosed in the above-mentioned patent application in Australia, nor has there been any commercial use in Australia of the methods disclosed in the above-mentioned patent application.

However, the above-mentioned measurement technique enables the remaining cover thickness to be measured across a very small portion of the width of the belt, typically 80-90mm compared to a total belt width of up to 2 metres, and more.

In theory, it would be possible to duplicate the apparatus of the above-mentioned patent application approximately 20-25 times and thereby be able to measure the remaining carry cover thickness across the entire width of the belt. However, since the ultrasonic and inductive sensors used in the above-mentioned apparatus are not inexpensive, such a duplication or replication is prohibitively expensive.

Summary of the Invention

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In accordance with a first aspect of the present invention there is disclosed a method as defined in claim 1.

In accordance with a second aspect of the present invention there is disclosed a method as defined in claim 7.

According to another aspect of the present invention there is provided an apparatus as defined in claim 10.

Brief Description of the Drawings A preferred embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings in which: Fig. 1A is a schematic perspective view of a tail pulley of a conveyor belt showing the preferred embodiment of the belt cover thickness monitoring instrument; Fig. 1B is a schematic block diagram of the circuitry of the belt cover thickness monitoring instrument of Fig. 1 Fig. 1C is an end elevation of the tail pulley which supports a steel cord conveyor belt, Fig. 2 is a side elevation of the apparatus of Fig. IC, Fig. 3 is a plan view of the linear slide illustrated in Figs. 1C and 2, Fig. 4 is a side elevation of the linear slide of Fig. 3, Fig. 5 is a schematic block diagram of the processor controller, Fig. 6 is a schematic representation of measurement locations, Fig. 7 is a sequence of three graphs each illustrating an average remaining cover profile, and Fig. 8 is a transverse average cover wear profile.

Detailed Description

As seen in Fig. 1A, a portion of a carry cover 107 of a belt is being measured by passing under a monitoring instrument 104 which is located above the tail pulley 127 of the conveyor. Alternatively, measurement of the pulley cover thickness is carried out somewhere else in the conveyor return run where the belt 106 is flat (in one plane) notwithstanding its motion.

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Irrespective of where the measurement is actually carried out, a transverse member 101 extends across the width of the belt 106 and has positioned on it a slotted mount 102 which carries a vertical actuator 103. The vertical actuator 103 incorporates a highly geared (6000:1) electric motor which enables it to move a parallelogram frame 121 vertically on the slotted mount 102.

The monitoring instrument 104 is connected to the vertical actuator 103 by means of the parallelogram frame 121 which ensures that the monitoring instrument 104 is maintained parallel to the relevant (as illustrated in the drawings the upper) surface of the belt 106 at all times. The vertical actuator 103 is able to move the monitoring instrument 104 between a retracted position in which the monitoring instrument 104 is raised well clear of the belt 106, and a lowered deployed position in which measurements are able to be taken.

The slotted mount 102 is capable of being moved to any one of a range of positions along the transverse member 101in order to ensure that the monitoring instrument 104 is sensing the desired longitudinal strip of the carry cover 107. As it will be explained in relation to Fig. IB, the monitoring instrument 104 includes an ultrasonic probe 110 and an inductive probe 111. A further ultrasonic probe is provided in the form of a lateral belt position probe 105 which monitors the sideways position of the belt 106 relative to the tail pulley 127 or some other fixed reference point. If the belt moves too far away from, or towards, the lateral probe 105 the measurement is discontinued to ensure that the desired lateral location of the belt is being measured.

Turning now to Fig. IB, as indicated by dashed lines in Fig. IB, the monitoring instrument 104 houses the ultrasonic vertical position probe 110 and the inductive steel cord distance probe 111. Both of these devices have linear outputs in the range of 4-2OmA over the sensing distance to their respective targets. The target for the ultrasonic probe 110 is the upper surface of the conveyor belt 106. The target for the inductive probe 111 is the adjacent surface (ie the top) of the steel cords 108 which are embedded within the conveyor belt 106. With the monitoring instrument 104 in its deployed position, the probe 110 has its sensing face at a known vertical distance, defined as Du above the belt 106. There is an air gap Da between the upper surface of

5004N-AU the belt and the sensing face of the inductive probe 111. In addition, the probe 111 has its sensing face a known vertical distance Dk below the sensing face of the probe 110.

The electric motor of the vertical actuator 103 can be made to rotate clockwise or counter clockwise by applying DC power to either of its motion inputs. This rotation is used to raise and lower the monitoring instrument 104. The direction of rotation, and thus the direction of raising or lowering, is achieved by toggling relays under control of a CPU 112.

Initially when power is turned on, the monitoring instrument 104 is moved into the retracted position, if not there already. The retracted position is a safe distance from the conveyor belt surface and this is detected by means of the microswitch 116. If the microswitch 116 is open a "park" routine is initiated to drive the monitoring instrument 104 upwardly until such time as the microswitch 116 is closed.

In order to take a measurement, a "deploy" routine is commenced. This can be initiated by means of a pre-set timer or from a remote live source. In this deploy mode, the vertical actuator 103 slowly lowers the monitoring instrument 104 towards the belt 106. During this time, the output of the ultrasonic probe 110 which corresponds with the distance Du is monitored by the CPU 112. When Du reaches a predetermined value, known as the deployed distance, the vertical actuator 103 is halted. The electric motor of the vertical actuator 103 has a characteristic due to its high gearing which results in its angular rotation being locked in the absence of power on its motion inputs, thus maintaining the monitoring instrument 104 stationary.

The deployed distance has a carefully selected value which ensures that both probes 110, 111 are operating within their linear range. Both probes have a near "dead zone" which should be avoided when selecting the value of the deployed distance.

The distance from the inductive probe 111 to the top of the steel cords 108 is Di which is the sum of the air gap Da and Dc the cover thickness. Since Du and Dk (fixed) are both known, Da is calculated as Du minus Dk. A simple calculation of Di

5004N-AU minus Da determines the cover thickness Dc. This simple calculation is performed by the CPU 12 to provide the cover thickness Dc.

This value is logged in the memory 113 of a non-volatile Data Logger, along with a Date/Time Stamp.

Values are typically read every 250mS, while the conveyor is running.

The Data Log is available for down loading either via a suitable modem 114 or the site WAN/LAN via Ethernet 115.

The "footprint" area of belt being measured is typically 100 x100mm.

A collision microswitch 117 is provided which activates if an object on the belt being measured comes in contact with the monitoring instrument 104 and the slotted mount 102 is forced to swing away. The "swing away" is a safety feature of the slotted mount 102 which allows it to swing in the direction of belt travel, in the event of a collision. The monitoring instrument 104 has a ramped leading edge to facilitate this swing.

If the collision microswitch 117 activates, the park routine is run.

A large value capacitor in the power supply 118 stores enough energy to park the monitoring instrument 104 in the event of a mains power failure while deployed.

The slotted mount 102 is positioned above the strip of belting deemed to be the lateral location of maximum wear.

Since belting can "wander" laterally on its structure, the lateral belt position probe 105 is provided to confirm to the CPU 112 that the belting is positioned correctly across the structure. If the belt 106 has wandered outside an operator set window, no cover thickness values are logged.

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Also, a signal is required to confirm the belt is running. This can be derived from a simple tacho generator 119 fitted to a local idler roller, or from the site PLC. No cover thickness values are logged if the belt is not running.

Pre-set data logging times can be programmed into the CPU so that measurements can be made under consistent ambient conditions, at night for example, where high temperatures are experienced during the day.

As explained above, the slotted mount 102 is capable of being moved to any one of a range of positions along the transverse member 101in order to ensure that the monitoring instrument 104 is sensing the desired longitudinal strip of the carry cover 107. In a further arrangement, the device has the slotted mount made to traverse the transverse member 101, so that a number of belt "strips" are measured, over time, and a 3D graphic generated, which shows the cover thickness across the entire width and length of the belting.

In the case of very short conveyors which run continuously, much of the time unloaded, the pulley cover is commonly worn out before the carry cover. In such cases, the pulley cover is the cover of interest which should be monitored.

The method and apparatus of the preferred embodiment to be described hereafter are based upon a realisation that if a transverse remaining cover thickness profile can be determined, then the location of the thinnest carry cover across the belt can be ascertained. Once this location is known, the single apparatus described Figs. 1A and 1B above and in the above-mentioned patent application can then be positioned at this location. Thereafter the resulting measurements of the remaining carry cover thickness at the location of minimum remaining carry cover thickness, can be used to accurately predict the remainder of the belt life, where loss of cover is the deciding factor. This is because the belt will wear out when the thinnest remaining carry cover thickness reaches the minimum operational thickness. In practice this minimum operational thickness is approximately zero and will become apparent when the steel cords of the belt become visible through the carry cover.

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Turning now to Figs. 1C and 2, a conveyor belt 1 passes over a tail pulley 2. In operation, the conveyor belt 1 can wander from left to right and right to left across the tail pulley 2. Mounted above the tail pulley 2 is a linear slide 3 which includes a cross bar 4 mounted between a pair of supports 5. The longitudinal axis of the crossbar 4 is mounted so as to be parallel to the axis of the tail pulley 2. In this way the crossbar 4 is in a plane which is parallel to the plane containing the reinforcing cords (not illustrated) of the conveyor belt 1. In addition, the crossbar 4 is perpendicular to the reinforcing cords.

The linear slide 3 includes a carriage 7 upon which is mounted the remaining cover thickness (RCT) sensor 9 being the apparatus disclosed in the above-mentioned Australian patent application and described and illustrated in Figs 1A and 1C. As seen in Fig. 3, the carriage 7 is mounted between a pair of concertina rubber boots 11, 12 and includes an absolute displacement sensor 14. Such a sensor can be fabricated using barcodes arranged in strips or an optical shaft encoder which detects pulses generated by the rotation of a shaft driven by a servo motor 16 and a reduction gearbox 17. The absolute displacement sensor 14 enables the instantaneous position of the carriage 7 on the slide to be known precisely.

It will be apparent to those skilled in the mechanical arts that the above-mentioned arrangement enables the servo motor 16 to be driven so as to move the RCT sensor 9 from left to right across the conveyor belt 1 and back again. The linear slide 3 produces very smooth uniform single plane movement of the carriage 7 and its RCT sensor 9. Various mechanisms are available to achieve this including a toothed belt and sprocket, a screw feeder, or a dial cord. Such mechanisms are located within the rubber boots 11, 12.

The linear slide 3 preferably over spans the conveyor belt 1 which therefore caters for belt wander. The linear slide 3 is orientated parallel to the plane of the conveyor belt and at right angles to the direction of travel of the conveyor belt and is securely mounted on the conveyor belt structure itself, by two supports 5 which allow for very precise and stable positioning above the belt surface being measured. If it is the carry cover of the belt 1 which is to be measured, as is usually the case, the linear slide 3 is

5004N-AU ideally positioned just after, and close to, the tail pulley 2. At this location the belt 1 is substantially in a single plane and substantially free from vibration and flapping.

The movement of the carriage 7 is controlled by a microprocessor 20 as illustrated in Fig. 5. The microprocessor 20 receives inputs from a number of different devices including a lateral position indicator (LPI) 21, a tachometer 22, a splice detector 23 and a high resolution surveillance camera 24. As schematically illustrated in Fig. 2, the lateral position indicator 21 is fitted to the conveyor structure and determines the lateral position of the conveyor belt 1 on the conveyor structure. The tachometer 22 is fitted to, and is driven by, the conveyor belt1 and consequently measures belt speed and longitudinal position along the belt path.

The splice detector 23 is located in the belt return strand and outputs a signal when a splice passes it. This detector is needed to eliminate measurement anomalies occurring in the data as splice cover thickness is measured, as opposed to the desired measurement of the thickness of the "parent" belt cover.

The camera 24 is attached to the conveyor structure and is framed to view the scanning location and the belt being measured. Images from the camera are available in real time over the Internet utilising either a modem 26 incorporated into the microprocessor 20 and an associated aerial 27, or a site network 29 which incorporates a Ethernet port, for example.

A number of measurement voltages are generated. The first of these (VI) is generated by the RCT sensor 9 and represents the finite cover thickness in mm. The second measurement voltage (V2) is generated by the absolute displacement sensor 14 and represents the location in mm of the RCT sensor 9 on the linear slide 3. This is always a positive value beyond a home base position, which is designated as zero. The third measurement voltage (V3) is generated by the lateral position indicator 21 and represents the lateral position in mm of the conveyor belt 1 on its structure. This voltage can be either positive or negative depending upon whether the belt 1 is wandering to the left or to the right, for example. This voltage is set to zero when the belt 1 is centred on the tail pulley 2. A fourth voltage (V4), in the form of a sequence of pulses, is generated by the tachometer 22 and is used to determine the longitudinal

5004N-AU position in mm of the belt in the belt path. All these measurement voltages are delivered to the microprocessor 20 which incorporates non-volatile memory 33.

Preferably before a measurement is commenced, the image being streamed by the surveillance camera 24 is reviewed to ensure the conveyor belt 1 upstream of the RCT sensor 9 is clean. Any carry back of product will give rise to noisy data so it is desirable to know that the belt 1 is reasonably clean before initiating a scan. In this connection rain falling on the conveyor belt 1 is one way of cleaning the belt. Another way of cleaning the belt 1 is to apply a high-pressure water or air hose to the conveyor belt 1 prior to and in the vicinity of the tail pulley 2.

Prior to commencing a scan, the RCT sensor 9 is located in its fully left or "home base" position. The sensor is located vertically so that when it executes its lateral travel above the belt, the sensor will be 30-40mm above the tops of the steel cords.

When the sensor 9 is parked in its home base location, it is positioned above a small rectangular sample of the belting being scanned. This sample is permanently fixed to the supporting structure of the conveyor belt and has a known cover thickness. This thickness has previously been established using a hand-held device, or by other means, and does not change since the sample does not experience any wear. The sample allows the RCT sensor 9 to verify that it is producing a correct cover thickness value prior to a scan. In this way, the sensor 9 can be calibrated and can be remotely known to be calibrated.

With a clean conveyor belt 1 and with the conveyor belt 1 running, the carriage 7 is driven from left to right and then from right to left for its full travel across the linear slide 3. This movement over spans the belt 1 on both sides. This produces a continuous sequence of zigs and zags as illustrated in Fig. 6. As a consequence, a measurement is taken at each of a series of spaced apart locations M1, M2, M3, etc. spaced along a diagonal line D1 notionally drawn across the conveyor belt 1. As the carriage 7 reverses, a second sequence of measurements is taken at each of a series of spaced apart locations M7 - M12. Then the procedure is repeated resulting in measurements being taken at each of locations M13 - M18, and then at location M19, and so on.

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The speed of the carriage 7 can be controlled so that preferably at least one complete pass (i.e. left to right or right to left) is achieved in every belt section between adjacent belt splices. Such belt sections can typically vary in length between 15 m and 750 m. Preferably, a number of radiofrequency identity (RFID) tags 32 are implanted into the body of the conveyor belt 1 at the location of each splice. The tags 32 are detected by an RFID reader 35 as the tags 32 pass the reader 35. The belt path distance in mm between the RFID reader 35 and the RCT sensor 9 is noted as a longitudinal offset. The output of the RFID reader 35 is delivered to the microprocessor 20. Each RFID tag 32 is assigned a unique identification number during its manufacture. Detection and identification of any RFID tag 32 allows the microprocessor 20 to establish what location along the endless belt length, within each section of the belt, is being recorded as the voltage Vlis produced.

The voltages VI, V2, V3, and V4 and the output from the RFID reader 35 are input into the microprocessor 20 and stored in its non-volatile memory 33 as a series of substantially simultaneous records. Preferably each record contains a timestamp and the time between adjacent records is preferably 20mS. Preferably measurements are taken from at least two belt revolutions, at which time the RCT sensor 9 and the carriage 7 are returned to "home base".

The microprocessor 20 is able to be remotely controlled by means of the modem 26 and aerial 27 in conjunction with the local mobile telephone (cell phone) service. Alternatively, the microprocessor 20 is able to be remotely controlled via the site network 29 via its Ethernet connection. This enables the stored data to be downloaded and processed either off-site, or if preferred, on-site.

As schematically illustrated in Fig. 6, for every measurement M1, M2, etc. there is both a value for the voltage VI and a lateral coordinate which is the result of the formula V2 minus the lateral offset of the home base (eg 250mm) minus V3. For every measurement, the values of voltage VI and the lateral coordinates are recorded.

In Fig. 7, for each of the three graphs, the Y axis is the voltage VI and the X axis is the lateral coordinate (ie the result of V2 - 250 - V3). The locations of skirt wear are

5004N-AU clearly visible and it will be seen that the carry cover thickness is actually thicker in the centre of the belt than to either side of centre. Each of the graphs of Fig. 7 is a result of a corresponding pass of the belt at three different positions along the belt. At the time of the pass which resulted in graph A, the belt was centred on the structure. At the time of the pass which resulted in graph B the belt had wandered 170mm to the left, and at the time of the pass which resulted in graph C the belt had wandered 75mm to the right.

For a 2000 mm wide belt travelling at 6000mm/sec the full travel of the carriage 9 is preferably 2500mm. A suitable lateral speed of the carriage 9 is in the range of 100 200mm/sec and a suitable sample logging rate is 20mS (50Hz) which results in a sample being logged in the range of from every 2mm to every 4mm of belt width. As a consequence, a full sweep takes between 12.5 and 25 seconds and produces a total number of between 625 and 1250 samples of which between 500 and 1000 samples are from the actual belt. The spatial location of the samples which are from the actual belt will vary with belt wander.

For those measurements, such as M6, M7, M18, M19, etc., where the lateral coordinates are found to be the same, the values of VI are summed so as to produce a total IV1 which is then divided by n, being the number of measurements with the same lateral coordinate. This gives an average cover thickness (EV1/n) along the belt for each lateral coordinate at which measurements were taken. This enables the graph of Fig. 8 to be produced which is a transverse average cover profile across the belt, which can also be termed a lateral average cover wear profile. This does not necessarily have a U or V shape as might be anticipated because materials are not necessarily symmetrically loaded onto a belt, and wear can be caused by other activities such as material turbulence during the material being conveyed from one location to another, belt scraping and cleaning, actions to restrict belt wandering, etc.

At those locations in the endless belt where there is a splice, this is recorded as an artificially thin cover thickness because of the extra steel present in the splice zone. Accordingly, the data from such splice locations are preferably ignored. Measurements which include part of a spice can be readily identified by reference to the output of the RFID reader 35 in conjunction with the longitudinal offset.

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The cover wear profile of Fig. 8 is then reviewed which enables the lateral location of the thinnest cover across the belt 1 to be established. In this particular embodiment, this location happens to be to the left of the centre of the belt. This then becomes the location where the RCT sensor of the above-mentioned Australian patent application is to be positioned for future longitudinal cover thickness measurements.

Whilst in most circumstances, it is usual for a cover profile, once established, to be constant for the life of the belt cover, in some instances the cover profile changes. In particular, in certain applications where the conveyed material is very dense and abrasive, and the operating conditions of the belt change with time, variations in the cover profile shape can occur relatively quickly. It is important to be aware if this is occurring since this will require that the belt be re-measured or scanned as described above, on a regular basis, a revised cover profile thereby established, and the lateral position of the RCT sensor moved to the new lateral location of thinnest belt cover. Comparing consecutive scans as described above in Fig. 7 enables the change in profile shape to be easily detected.

It will be apparent to those skilled in the art that the cover wear profile produced by the method described above is a true measurement of the profile of the cover thickness. This is to be contrasted with the overall belt thickness profile produced by the prior art, such as the above-mentioned laser or ultrasonic probe methods, which do not sense the actual position of the tops of the steel cords.

The foregoing describes only one embodiment of the present invention and modifications, obvious to those skilled in the conveyor belt arts, can be made thereto without departing from the scope of the present invention. For example, the RCT sensor 9 can be raised or lowered in a vertical direction so as to ensure there is no impact between the belt and the RCT sensor 9. However, it is simpler not to raise or lower the RCT sensor but merely to move the carriage 7 to its "home base" and thus to one side of the belt where it is also safe from collision with the belt.

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The term "comprising" (and its grammatical variations) as used herein is used in the inclusive sense of "including" or "having" and not in the exclusive sense of "consisting only of'.

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Claims (18)

1. CLAIMS 1. A method of determining remaining cover thickness in a steel cord conveyor belt whilst the belt is moving, said method comprising the steps of: mounting adjacent said belt an apparatus comprising: an ultrasonic probe to ultrasonically measure a first distance from a known data point to the relevant surface of said belt, an inductive probe to inductively measure a second distance from a second known data point to said steel cords, and computing means connected to said ultrasonic probe and said inductive probe to subtract said second distance from said first distance taking the distance between said known data points into account to estimate said cover thickness, said apparatus being mounted such that said probes are moveable transversely across the belt at an unloaded location on said belt, and moving said apparatus from one side of said belt to the other whilst taking a series of remaining cover thickness measurements whilst the belt is moving to thereby measure remaining cover thickness at a first plurality of locations spaced apart along a line notionally drawn across said belt and inclined to the longitudinal axis of the belt.
2. 2. The method as claimed in claim 1 wherein said apparatus is moved from said one side to said other side and back again to thereby measure remaining cover thickness at a second plurality of locations spaced apart along a V-shaped line notionally drawn across said belt.
3. 3. The method as claimed in claim 2 including the further steps of: repeating the measurement of claim 2 for at least a plurality of complete belt resolutions, and for each measured transverse location on said belt determining an average belt cover thickness at that location by summing those measurements having the same transverse location and dividing the total thickness by the number of those measurements.
4. 4. The method as claimed in any one of claims 1-3 including the step of: measuring lateral wander of said belt and determining the position of

   5004N-AU said transverse location with reference to a known belt position.
5. 5. The method as claimed in claim 4 wherein said known belt position is the position of said belt when centred on its supporting structure.
6. 6. The method as claimed in claim 3, or claims 4 and 5 when dependent upon claim 3, including the further step of: for each measured transverse location across said belt, determining said average belt cover thickness to thereby form an average belt cover thickness profile.
7. 7. A method of predicting the expected date at which the cover of a steel cord conveyor belt will reach the end of its working life, said method comprising the steps of: determining said average belt cover profile by carrying out the method as claimed in claim 6 on a plurality of occasions in order to determine the change in average belt cover profile with time, and extrapolating said change to predict when a predetermined minimum belt cover thickness will be reached.
8. 8. The method as claimed in any one of claims 1-7 wherein said cover is the carry cover.
9. 9. The method as claimed in any one of claims 1-7 wherein said cover is the pulley cover.
10. 10. Apparatus for determining remaining cover thickness of a moving conveyor belt having steel cords and extending between a tail pulley and a discharge pulley, said apparatus comprising: an ultrasonic probe to ultrasonically measure a first distance from a known data point to the relevant surface of said belt, an inductive probe to inductively measure a second distance from a second known data point to said steel cords, and computing means connected to said ultrasonic probe and said inductive probe to

    5004N-AU subtract said second distance from said first distance taking the distance between said known data points into account to estimate said cover thickness, said apparatus being mounted for transverse operational movement from one side of said belt to the other side of said belt while said belt is moving at a location where said belt is unloaded.
11. 11. The apparatus as claimed in claim 10 wherein said location is downstream from, but closely adjacent to, the tail pulley of said belt.
12. 12. The apparatus as claimed in claim 10 or 11 and including lateral belt measurement means to measure the lateral movement, if any, of said belt from a predetermined belt position.
13. 13. The apparatus as claimed in claim 12 wherein said predetermined belt position is the position of said belt when centred on its supporting structure.
14. 14. The apparatus as claimed in any one of claims 10 - 13 and including longitudinal belt position measuring means.
15. 15. The apparatus as claimed in claim 1 wherein said longitudinal belt position measuring means comprise a multiplicity of longitudinally spaced apart RFID devices.
16. 16. The apparatus as claimed in claim 15 wherein each adjacent pair of said RFID devices corresponds to, and is spaced apart in accordance with the spacing between, adjacent belt splices.
17. 17. The apparatus as claimed in any one of claims 10-16 wherein said apparatus is mounted to measure the carry cover of said belt.
18. 18. The apparatus as claimed in any one of claims 10-16 wherein said apparatus is mounted to measure the pulley cover of said belt.

    5004N-AU

    Dated this 16th day of July 2020

    BELT WATCH PTY LIMITED

    By FRASER OLD & SOHN Patent Attorneys for the Applicant

    5004N-AU