Note: Descriptions are shown in the official language in which they were submitted.
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A BELT RIP DETECTION SYSTEM
Field of the Invention
The present invention relates to a belt rip detection system for detecting a
rip in a belt
of a conveyor, and in particular for detecting a rip in a belt of a conveyor
of the type
used to transport material in a mining operation.
Background of the Invention
It is known to use conveyors in the resources industry to transport material
between
different stages and/or different components of a production workflow. For
example in
an iron ore production facility, it is typical to use conveyors to transport
ore to/from
crushing equipment, transportation trains, and equipment at a port facility.
Such
conveyors are critical to the production process and as a consequence any
downtime
of a conveyor can have a significant effect on production and therefore cost.
A belt rip that is less than the full length of the conveyor, for example up
to 150m, can
be temporarily repaired with mechanical fasteners, with a proper repair
typically done
in the next scheduled shutdown. Full length belt rips, however, require
immediate
replacement and therefore immediate shutdown of the conveyor, which is
expensive in
terms of both loss of production and materials cost for a new conveyor belt.
It is therefore desirable to avoid occurrence of full length rips and the
associated effect
on production downtime and cost.
Summary of the Invention
In accordance with a first aspect of the present invention, there is provided
a belt rip
detection system for a conveyor including a conveyor belt, the system
comprising:
a belt separator including at least two idler rollers, the belt separator
arranged
to support the conveyor belt on the at least two idler rollers, and to induce
a change in
profile of the conveyor belt when a rip is present in the conveyor belt as a
portion of the
conveyor belt including the rip passes over the belt separator; and
at least one sensor arranged to produce information indicative of a profile of
at
least a portion of the conveyor belt, the at least one sensor disposed so as
to produce
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information indicative of a profile of at least a portion of the conveyor belt
from below
the conveyor belt;
the system arranged to use the information indicative of the profile of at
least a
portion of the conveyor belt to produce information indicative of the change
in profile of
the conveyor belt adjacent a rip in the conveyor belt and thereby presence of
the rip in
the conveyor belt.
In an embodiment, the belt separator includes first and second oppositely
disposed
inclined rollers arranged to support the conveyor belt, with no support for
the conveyor
belt between the first and second inclined rollers.
In an embodiment, the angle of inclination of the first and second rollers is
adjustable
and thereby support points of the conveyor belt are adjustable.
In an embodiment, a spacing distance between the first and second rollers is
adjustable and thereby support points of the conveyor belt are adjustable.
In an embodiment, the system includes a plurality of sensors, each sensor
arranged to
produce conveyor belt profile information for a substantially different
portion of the
conveyor belt, and the system arranged to use the profile information from any
one or
more of the sensors to determine whether a rip is present in the conveyor
belt.
In an embodiment, the at least one sensor includes at least one laser scanner
arranged to scan across at least a section of the conveyor belt and produce
distance
information indicative of a profile of the conveyor belt section as the laser
scans across
the conveyor belt section. The laser scanner may include a plurality of laser
sensors,
each laser sensor arranged to scan across a substantially different portion of
the
conveyor belt section and produce distance information indicative of a profile
of the
conveyor belt portion as the laser scans across the conveyor belt portion.
In an embodiment, the at least one sensor includes a plurality of direct line
of sight
sensors, each direct line of sight sensor arranged to provide a signal
indicative of the
distance to the conveyor belt along a different direct line of sight, wherein
the lines of
sight of the sensors are substantially parallel. The lines of sight may extend
generally
horizontally.
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In an embodiment, the at least one sensor includes at least one ultrasonic
sensor. A
plurality of ultrasonic sensors may be provided, each ultrasonic sensor
arranged to
cover a substantially different portion of the conveyor belt and produce
distance
information indicative of a profile of the conveyor belt portion.
In an embodiment, the at least one sensor includes at least one radar sensor.
In an embodiment, the at least one sensor includes at least one inductive
sensor.
In an embodiment, the system includes a display arranged to visually display
the
information indicative of the change in profile of the conveyor belt adjacent
a rip in the
conveyor belt.
In an embodiment, the system is arranged to automatically compare the
information
indicative of the change in profile of the conveyor belt adjacent a rip in the
conveyor
belt with reference conveyor belt profile information and to generate an alert
signal
when the comparison indicates that a rip is present in the conveyor belt. The
alert
signal may be communicated to a control system of the conveyor belt.
In an embodiment, the reference information may comprise a load factor signal
representing expected deviation of the conveyor belt in response to an applied
load
when the conveyor belt is not ripped, the load factor signal derived using a
mathematical model of a loaded belt.
In an embodiment, the reference information may comprise a lookup table of
reference
sensor values for a loaded belt.
In accordance with a second aspect of the present invention, there is provided
a
method of detecting a rip in a conveyor belt of a conveyor, the method
comprising:
providing a belt separator including at least two idler rollers;
supporting the conveyor belt on the at least two idler rollers, the belt
separator
arranged to induce a change in profile of the conveyor belt when a rip is
present in the
conveyor belt as a portion of the conveyor belt including the rip passes over
the belt
separator;
using at least one sensor arranged to produce information indicative of a
profile
of at least a portion of the conveyor belt, the at least one sensor disposed
so as to
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produce information indicative of a profile of at least a portion of the
conveyor belt from
below the conveyor belt; and
using the information indicative of the profile of at least a portion of the
conveyor belt to produce information indicative of the change in profile of
the conveyor
belt adjacent a rip in the conveyor belt and thereby presence of the rip in
the conveyor
belt.
Brief Description of the Drawings
The present invention will now be described, by way of example only, with
reference to
the accompanying drawings, in which:
Figure 1 is a schematic block diagram of components of a belt rip detection
system in
accordance with an embodiment of the present invention;
Figure 2 is a diagrammatic representation of a belt separator of the belt rip
detection
system, components of which are shown in Figure 1;
Figure 3 is a plot of a profile of a portion of a conveyor belt wherein the
belt portion
does not have a rip, the plot obtained using a laser scanner;
Figure 4 is a plot of a profile of a portion of a conveyor belt wherein the
belt portion
includes a rip, the plot obtained using a laser scanner;
Figure 5 shows plots indicative of a profile of a portion of a conveyor belt
wherein the
belt portion includes a rip, each plot corresponding to a respective channel
of a laser
scanner and each plot corresponding to a different view direction of the laser
scanner;
Figure 6 shows plots indicative of a profile of a portion of a conveyor belt
where the
belt portion includes a rip, the plots obtained using ultrasonic sensors;
Figure 7 shows plots indicative of a profile of a portion of a conveyor belt
where the
belt portion includes a rip, the plots obtained using ultrasonic sensors and
over a
longer time period than the plots shown in Figure 6;
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Figure 8 is a diagrammatic representation of a conveyor belt and set of
ultrasonic and
radar sensors of a belt rip detection system in accordance with an embodiment
of the
present invention when no rip is present in the belt;
5 Figure 9 is a diagrammatic representation of components of a belt rip
detection system
similar to the system shown in Figure 8 when a central rip is present in the
belt;
Figure 10 is a diagrammatic representation of components of the belt rip
detection
system shown in Figure 9 when a skirt rip is present in the belt;
Figure 11 shows plots indicative of a profile of a portion of a conveyor belt
where the
belt portion includes a rip, each plot corresponding to a respective
ultrasonic sensor of
the system shown in Figure 8 and each plot corresponding to a different view
direction;
Figure 12 shows the plots of Figure 11 after filtering and application of rip
detection
logic;
Figure 13 is a diagrammatic representation of components of a belt rip
detection
system in accordance with an alternative embodiment of the present invention
when no
rip is present in the belt, the system using alternative scanners to produce
information
indicative of the change in profile of the belt;
Figure 14 is a diagrammatic representation of components of the belt rip
detection
system shown in Figure 13 when a central rip is present in the belt; and
Figure 15 is a diagrammatic representation of components of the belt rip
detection
system shown in Figure 13 when a skirt rip is present in the belt.
Description of an Embodiment of the Invention
Referring to Figures 1 and 2 of the drawings, there is shown a belt rip
detection system
for detecting a rip in a conveyor belt 12 of a conveyor, in particular a
conveyor used in
the resources industry.
The system includes operative components 10 shown in Figure 1 and a belt
separator
14 shown in Figure 2.
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The system operates such that the belt separator 14 supports a conveyor belt
12 and
induces a change in profile of the conveyor belt 12 adjacent a rip when a rip
is present
in the conveyor belt 12, and one or more sensors are used detect the change in
profile
of the conveyor belt 12 and thereby presence of the rip in the conveyor belt
12.
The belt separator 14 shown in Figure 2 includes a frame 16, in this example
having a
base portion 18, end portions 19, and first and second roller mount portions
20, 22
arranged to rotatably support respective first and second idler rollers 24,
26. The first
and second idler rollers 24, 26 are connected to the base portion 18 at one of
several
pivot connections 23 and to a respective end portion 19 at one of several
roller mount
connections 25 through a support rod 29, the length of which between the end
portion
19 and the roller mount portion 20, 22 is adjustable. In this way, the
separation
distance between the first and second idler rollers 24, 26 and the angle of
inclination of
the idler rollers 24, 26 is adjustable, for example by adjusting the location
of the pivot
connection 23 of the roller mount portions 20, 22, adjusting the location of
the roller
mount connection 25 to which the support rod 29 is connected, and/or adjusting
the
length of the support rod 29.
Modifying the idler roller separation distance and/or the angle of inclination
of the idler
rollers 24, 26 enables the support locations of the conveyor belt 12 indicated
by arrows
27 to be modified, and it will be understood that facilitating modification of
the support
locations 27 enables the profile change of the conveyor belt 12 in response to
a belt rip
to be made more detectible, particularly for rips that occur at skirt portions
of the
conveyor belt 12. It will also be understood that increasing the angle of
inclination of
the idler rollers 24, 26 has a squeezing effect on the conveyor belt 12.
The inventors have established that supporting the conveyor belt 12 towards
longitudinal edges of the conveyor belt 12 increases the likelihood that a
detectible
profile change will occur in response to a rip in the conveyor belt 12 because
profile
changes are more likely to occur between the support points and less likely to
occur
outwardly of the support points. Accordingly, a rip occurring between the
support
points is more likely to be detectable than a rip outside of the support
points. Also, the
inventors have established that the squeezing effect caused by increasing the
angle of
inclination of the idler rollers 24, 26 also increases the likelihood that a
detectible
profile change will occur in response to a rip in the conveyor belt.
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As shown in Figure 2, the belt separator 14 includes a void region 28 between
the first
and second idler rollers 24, 26. In a conventional belt idler assembly, a
central idler
roller would be provided that is rotatable about a generally horizontal axis,
the central
idler roller providing a degree of support for a belt in addition to the
support provided
.. by 2 side idler rollers. However, the inventors have established that the
presence of a
central idler roller reduces the amount of profile change that occurs in a
belt when the
belt is ripped and as a consequence a rip is more difficult to detect. Without
the central
idler roller, belt sag in response to a rip is more pronounced and therefore
more likely
to be detectible as a profile change.
The operative components 10 shown in Figure 1 include at least one sensor 30
that is
configured to produce information indicative of a profile of the belt, which
can then be
used to determine whether a change of significance has occurred to the belt
profile
and thereby whether a rip is present in the belt. In this embodiment, a sensor
.. assembly including several sensors, for example 8 sensors, is provided. The
sensors
may be any suitable sensors capable of producing information indicative of the
profile
of the belt, for example laser sensors, ultrasonic sensors, inductive sensors
and/or
radar sensors. In the present described embodiments, each sensor is arranged
to
detect distance to a conveyor belt in a field of view of the sensor without
touching the
.. conveyor belt, although it will be understood that alternatives are
envisaged. For
example, an arrangement may be provided whereby a roller mounted on a movable
arm touches the conveyor belt and belt profile information is generated in
response to
movement of the arm.
The operative components 10 also include a control unit 32 arranged to control
and
coordinate operations in the system and in particular implement an analysis
engine 34
arranged to use signals produced by the sensors 30 to produce profile
information that
can be used by an operator to determine whether a rip is likely to be present.
For
example, in the present embodiment, the analysis engine 34 is arranged to
automatically compare the detected profile with a reference profile for the
conveyor belt
12 and to generate an alert signal when the detected profile exceeds a defined
threshold compared to the default profile. The alert signal in this example is
communicated directly to a conveyor belt control system, such as a PLC of the
conveyor belt control system.
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The analysis engine 34 may also be arranged to determine when a sensor is
operating
incorrectly, for example because the sensor blocked, and to trigger an alert
to indicate
that the sensor requires cleaning.
.. The analysis engine 34 may also be arranged to produce information
indicative of a
visual representation of the belt profile for display to the operator, for
example one or
more plots indicative of the profile of the conveyor belt 12. For this
purpose, the
operative components 10 may also include a display 40 for displaying
information to an
operator indicative of the determined belt profile.
In this example, the control unit includes a processor 35 and the operative
components
10 also include a data storage device 36 arranged to store programs and data
used by
the processor 35 to implement the desired functionality, and a memory 36 used
by the
processor to temporarily store programs and/or data during use.
The operative components 10 may include an alert unit 42 arranged to produce
an
alert, for example a visible or audible alert to an operator, when the
analysis engine 34
generates an alert signal to indicate that the detected profile exceeds a
defined
threshold compared to a reference profile.
Referring to Figure 3, a plot 44 is shown that illustrates distance
measurements
obtained from a laser scanner that has a conveyor belt in a field of view of
the laser
scanner. Since the laser scanner measures distance from the laser scanner to
an
object across a field of view of the laser scanner, the plot 44 is therefore
representative
of the profile of the belt. As shown, while some noise is present, a general
belt profile
represented by broken line 45 can be seen.
Referring to Figure 4, a plot 46 is shown that illustrates distance
measurements
obtained from the laser scanner that has a ripped conveyor belt in the field
of view of
the laser scanner. The plot 46 includes a first profile portion 47 that
corresponds to an
upper portion of a side of the belt, and second profile portion 48 that
corresponds to a
lower portion of the belt. As shown, while some noise is present, it is clear
that a
discontinuity 50 is present between the first and second profile portions, and
that the
second profile portion 48 sags relative to the first profile portion 47. This
indicates that
a rip is present in the conveyor belt 12 between the first and second profile
portions. A
general ripped belt profile without noise is represented by broken line 51.
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Instead of a single laser scanner that is arranged to scan across the surface
of the belt
in order to produce a continuous belt profile, the sensor(s) 30 may take the
form of one
or more laser scanners or direct line sensors of the type arranged to provide
distance
data in separate channels.
In an example, 8 data plots 52, 54, 56, 58, 60, 62, 64 as shown in Figure 5
are
produced by a plurality of laser scanners. Each plot corresponds to a
different
direction of view of a laser scanner and therefore each plot corresponds to a
different
portion of the section of belt that faces the laser scanners. In this example,
therefore,
a first plot 52 corresponds to an upper portion of a side of the belt and an
eighth plot
64 corresponds to a lower portion of the side of the belt adjacent a central
portion of
the belt.
Referring to Figure 6, plots 66, 68 are shown that illustrate distance
measurements
obtained from an ultrasonic distance measuring device. A first plot 66
corresponds to
a first ultrasonic sensor of the device and a second plot 68 corresponds to a
second
ultrasonic sensor of the device. As with the laser scanner described above,
the
ultrasonic device measures distance from the device to an object in the field
of view of
the device, and the plots 66, 68 are therefore representative of the profile
of the belt at
2 locations. In this example, the first plot 66 corresponds to a lower portion
of a side of
the belt and the second plot 68 corresponds to an upper portion of the same
side of
the belt.
It can be seen from Figure 6 that a discontinuity 69 exists that represents a
skirt rip. A
center rip 67 is also detected. The second plot 68 does not detect the skirt
rip because
it is placed too high relative to the belt. In this way, the second ultrasonic
sensor
serves to provide a default plot of the belt that is less likely to respond to
rips in the
belt.
Figure 7 shows first and second plots 70, 72 for the respective first and
second
ultrasonic sensors over a longer time period than the plots 66, 68 shown in
Figure 6.
Referring to Figure 8, diagrammatic representations of components of a belt
rip
detection system in accordance with an embodiment of the present invention are
shown.
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In this example, a group of ultrasonic sensors 74 and radar sensors 76 are
used to
detect distance between the sensors and an adjacent belt 12. In this example,
6
ultrasonic sensors 74 and 2 radar sensors 76 are used. In this example, each
ultrasonic sensor has a sensor field of view 80 corresponding to an
approximate
5 200mm spot size directed upwardly towards the conveyor belt 12 and
covering a
different part of the conveyor belt 12, and each ultrasonic sensor 74 is
arranged to
provide a signal indicative of the minimum distance to an object in the field
of view. It
will however be understood that sensors with other spot sizes are envisaged.
10 Figure 9 shows the position of the conveyor belt 12 relative to the
field of view 80 of a
set of 8 ultrasonic sensors when a center rip 82 is present in the belt. Like
and similar
features are indicated with like reference numerals. As shown in Figure 9, a
rip 82 in
the centre of the conveyor belt 12 causes a central portion of the belt to
sag, and as a
consequence the distance measurements produced by the 41h and 5th sensors will
detectably reduce. There may also be a small change in the distance
measurements
produced by the 3rd and 6th sensors, but most likely no identifiable change in
the
distance measurements produced by the 1s1 and 8th sensors.
Figure 10 shows the position of the conveyor belt 12 relative to the field of
view 80 of
the sensors when a skirt rip 84 is present in the belt. As shown in Figure 10,
a rip 82 in
a skirt portion of the conveyor belt 12 causes minor sagging adjacent the
skirt rip 84,
and as a consequence the distance measurements produced by the 6th and 7th
sensors will detectably reduce. There is likely to be no identifiable change
in the
distance measurements produced by the 1st, 2nd, 3rd, 4th, 5th an, =-=th
sensors.
It will be appreciated, therefore, that a change in 1 or 2 of the 8 sensors
can be used to
indicate a rip in the conveyor belt 12.
Figure 11 shows plots 85 derived from the ultrasonic sensors 74 shown in
Figure 8, the
plots 85 corresponding to raw signals indicative of distance to the conveyor
belt from
each of the sensors 74. As each sensor 74 corresponds to a different field of
view, the
raw signal derived from each sensor 74 is indicative of whether a rip is
present at a
portion of the conveyor belt 12 in the field of view 80 of the sensor. Figure
11 also
includes a plot 86 of conveyor belt load.
It will be appreciated that the profile of a belt with no rips changes
significantly with
changes in load, and accordingly in order to determine changes in belt profile
in
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response to presence of a rip, it is necessary to generate reference data
indicative of a
loaded belt with no rips and to compare the measured profile data with the
reference
data in order to determine whether a rip is present. The reference data may be
derived
in any suitable way, for example using a mathematical model of a loaded belt
or using
a lookup table of reference sensor values for a loaded belt.
Figure 12 shows plots 88 that correspond to the ultrasonic sensor-derived
plots 85 of
Figure 11 after filtering, a plot 90 indicative of a load factor representing
expected
vertical deviation of the conveyor belt in response to an applied load
represented by
the load plot 86, and a plot 92 that includes pulses 94 indicative of detected
rips in the
conveyor belt 12.
By filtering the raw signals represented by the plots 85 in Figure 11 using
the load
factor plot 90, filtered signals represented by plots 88 are produced. Using
the filtered
signal plots 88, a rip on the conveyor belt 12 can be detected, and pulses 94
generated corresponding to the location(s) of the rip(s). In the present
example, a
generated pulse 94 is provided to a PLC of a conveyor belt control system.
In a particular example, the following methodology is used.
Based on raw signals from the ultrasonic sensors, and prior to loading the
conveyor
belt, steady state sensor signals are produced that represent the profile of
the
conveyor belt when the conveyor belt is not loaded and when no rips are
present in the
belt. During use with the conveyor belt loaded, signals indicative of the
loaded profile
.. of the conveyor belt are obtained from the ultrasonic sensors. A transverse
belt load
factor based on a belt sag model is determined empirically from test data, and
an error
signal is determined by comparing the measured loaded profile signals with the
expected loaded profile determined using the determined belt load factor. A
moving
average, for example of 10 successive determined values in the error signal,
is then
determined, and if there is a deviation greater than a defined threshold, for
example a
reduction in distance to the belt of 8mm or greater, a pulse 94 is added to
the detected
rip plot 92 to indicate that a rip is considered to be present in the conveyor
belt 12.
Referring to Figures 13 to 15, diagrammatic representations of components of a
belt rip
detection system in accordance with an alternative embodiment of the present
invention are shown.
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In this example, a plurality or group of laser sensor assemblies 100 are used
to detect
distance between the laser sensors and an adjacent belt, and each laser sensor
assembly 100 includes 11 laser sensors. Each laser sensor is arranged to
provide a
signal indicative of the minimum distance to an object in the field of view
located along
a direct line of sight 102 extending generally horizontally from the sensor,
and the
sensors are configured so that the lines of sight 102 of the sensors are
parallel.
Figure 13 shows the position of the conveyor belt 12 relative to the lines of
sight 102 of
the sensors when no rip is present in the conveyor belt 12. As shown, the
lowermost
sensor is disposed such that the line of sight passes slightly under the
central portion
of the conveyor belt 12.
Figure 14 shows the position of the conveyor belt 12 relative to the lines of
sight 102 of
the sensors when a center rip 104 is present in the belt. As shown in Figure
14, a rip
104 in the centre of the conveyor belt 12 causes a central portion of the belt
to sag,
and as a consequence the distance measurements produced by the first 4 sensors
will
detectably reduce. There will most likely be no identifiable change in the
distance
measurements produced by the 5th to 8th sensors.
Figure 15 shows the position of the conveyor belt 12 relative to the lines of
sight 102 of
the sensors when a skirt rip 106 is present in the belt. As shown in Figure
15, a rip 106
in a skirt portion of the conveyor belt 12 causes minor sagging adjacent the
skirt rip
106, and as a consequence the distance measurements produced by the 7th and
8th
sensors will detectably reduce. There is likely to be no identifiable change
in the
distance measurements produced by the 1st to 6th and 9th to 11th sensors.
It is to be understood that, if any prior art publication is referred to
herein, such
reference does not constitute an admission that the publication forms a part
of the
common general knowledge in the art, in Australia or any other country.
In the claims which follow and in the preceding description of the invention,
except
where the context requires otherwise due to express language or necessary
implication, the word "comprise" or variations such as "comprises" or
"comprising" is
used in an inclusive sense, i.e. to specify the presence of the stated
features but not to
preclude the presence or addition of further features in various embodiments
of the
invention.
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Modifications and variations as would be apparent to a skilled addressee are
determined to be within the scope of the present invention.
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