AU2012216769A1

AU2012216769A1 - Conveyor Belt Cover Thickness Monitor

Info

Publication number: AU2012216769A1
Application number: AU2012216769A
Authority: AU
Inventors: Barry Charles Brown
Original assignee: BELT WATCH Pty Ltd
Current assignee: Bemo Pty Ltd
Priority date: 2011-09-13
Filing date: 2012-09-12
Publication date: 2013-03-28
Anticipated expiration: 2032-09-12
Also published as: AU2012216769B2

Abstract

An apparatus for, and method of, measuring the thickness of one cover (7) of a steel cord reinforced conveyor belt (6) is disclosed. An ultrasonic probe (10) measures a first distance Du from the probe (10) to the surface (7) of the belt. An inductive probe (11) measures a second distance Di from the inductive probe (11) to the steel cords (8). The cover thickness is determined by a simple arithmetic calculation.

Description

1 AUSTRALIA Patents Act 1990 5 COMPLETE SPECIFICATION FOR A STANDARD PATENT 10 ORIGINAL Name of Applicant(s): BELT WATCH PTY LIMITED 15 Actual Inventor(s): Barry Charles BROWN Address for Service: FRASER OLD & SOHN Patent Attorneys PO Box 560 20 MILSONS POINT NSW 1565 Invention Title: CONVEYOR BELT COVER THICKNESS MONITOR 25 Details of Associated Provisional Applications: 2011 903 724 and 2011 903 771 Dated 13 September 2011 and 14 September 2011 30 The following statement is a full description of this invention, including the best method of performing it known to us: 35 rAfAAT7 ATT CONVEYOR BELT COVER THICKNESS MONITOR Field of the Invention The present invention relates to the monitoring of belt conveyors having steel 5 reinforcing cords. 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 10 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. 15 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 20 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). 25 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 30 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 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 5 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. 10 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. 15 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 20 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 25 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. Genesis of the Invention 30 The genesis of the present invention is a desire to predict accurately the end-of-life date in a belt cover. It is desirable to identify the locations of minimum cover thickness in every belt section. In order to achieve this, a method needs to be devised which measures the cover thickness along the belting. Because of the significant C AA/L ATT lengths of belt involved, a practical method will need to make this measurement with the belt running. The following describes a device which makes this possible. Further, the device 5 described not only provides for determination of the points of minimum cover thickness along the belting but also facilitates on-line trending of the loss of cover in the belting against time and/or tonnage data. This is done without the necessity to stop the conveyor. 10 Summary of the Invention In accordance with a first aspect of the present invention there is disclosed a method of measuring the thickness of one cover of a steel cord reinforced conveyor belt whilst the belt is moving, said method comprising the steps of: ultrasonically measuring a first distance from a known data point to the relevant 15 surface of said belt, inductively measuring a second distance from a second known data point to the adjacent surface of the steel reinforcing cords, and subtracting said second distance from said first distance taking the distance between said known data points into account, to estimate said one cover thickness. 20 In accordance with a second aspect of the present invention there is disclosed a belt cover thickness monitoring apparatus for measuring the thickness of one cover of a steel cord reinforced conveyor belt, said apparatus comprising: an ultrasonic probe to ultrasonically measure a first distance from a known data 25 point to the relevant surface of said belt, an inductive probe to inductively measure a second distance from a second known data point to the adjacent surface of said steel reinforcing 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 30 known data points into account, to estimate said one thickness. Preferably, the two probes are mounted together in a housing movable from a retracted standby position towards said relevant belt surface to a deployed position in which each probe is operating in a substantially linear mode. -~if A-T A Y Brief Description of the Drawings One embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings in which: Fig. 1 is a schematic perspective view of a tail pulley of a conveyor belt 5 showing the preferred embodiment of the belt cover thickness monitoring instrument; and Fig. 2 is a schematic block diagram of the circuitry of the belt cover thickness monitoring instrument of Fig. 1. 10 Detailed Description As seen in Fig. 1, a portion of a carry cover 7 of a belt is being measured by passing under a monitoring instrument 4 which is located above the tail pulley 27 of the conveyor. Alternatively, measurement of the pulley cover thickness is carried out somewhere else in the conveyor return run where the belt 6 is flat (in one plane) 15 notwithstanding its motion. Irrespective of where the measurement is actually carried out, a transverse member 1 extends across the width of the belt 6 and has positioned on it a slotted mount 2 which carries a vertical actuator 3. The vertical actuator 3 incorporates a highly geared 20 (6000:1) electric motor which enables it to move a parallelogram frame 21 vertically on the slotted mount 2. The monitoring instrument 4 is connected to the vertical actuator 3 by means of the parallelogram frame 21 which ensures that the monitoring instrument 4 is maintained 25 parallel to the relevant (as illustrated in the drawings the upper) surface of the belt 6 at all times. The vertical actuator 3 is able to move the monitoring instrument 4 between a retracted position in which the monitoring instrument 4 is raised well clear of the belt 6, and a lowered deployed position in which measurements are able to be taken. 30 The slotted mount 2 is capable of being moved to any one of a range of positions along the transverse member 1 in order to ensure that the monitoring instrument 4 is sensing the desired longitudinal strip of the carry cover 7. As it will be explained in relation to Fig. 2, the monitoring instrument 4 includes an ultrasonic probe 10 and an 0 inductive probe 11. A further ultrasonic probe is provided in the form of a lateral belt position probe 5 which monitors the sideways position of the belt 6 relative to the tail pulley 27 or some other fixed reference point. If the belt moves too far away from, or towards, the lateral probe 5 the measurement is discontinued to ensure that the desired 5 lateral location of the belt is being measured. Turning now to Fig. 2, as indicated by dashed lines in Fig. 2, the monitoring instrument 4 houses the ultrasonic vertical position probe 10 and the inductive steel cord distance probe 11. Both of these devices have linear outputs in the range of 4 10 20mA over the sensing distance to their respective targets. The target for the ultrasonic probe 10 is the upper surface of the conveyor belt 6. The target for the inductive probe 11 is the adjacent surface (ie the top) of the steel cords 8 which are embedded within the conveyor belt 6. With the monitoring instrument 4 in its deployed position, the probe 10 has its sensing face at a known vertical distance, 15 defined as Du above the belt 6. There is an air gap Da between the upper surface of the belt and the sensing face of the inductive probe 11. In addition, the probe 11 has its sensing face a known vertical distance Dk below the sensing face of the probe 10. The electric motor of the vertical actuator 3 can be made to rotate clockwise or 20 counter clockwise by applying DC power to either of its motion inputs. This rotation is used to raise and lower the monitoring instrument 4. The direction of rotation, and thus the direction of raising or lowering, is achieved by toggling relays under control ofa CPU 12. 25 Initially when power is turned on, the monitoring instrument 4 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 16. If the microswitch 16 is open a "park" routine is initiated to drive the monitoring instrument 4 upwardly until such time as the microswitch 16 is closed. 30 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 3 slowly lowers the monitoring instrument 4 towards the belt 6. During this time, the output of the ultrasonic probe 10 which corresponds with CAAAT7 ATT the distance Du is monitored by the CPU 12. When Du reaches a predetermined value, known as the deployed distance, the vertical actuator 3 is halted. The electric motor of the vertical actuator 3 has a characteristic due to its high gearing which results in its angular rotation being locked in the absence of power on its motion 5 inputs, thus maintaining the monitoring instrument 4 stationary. The deployed distance has a carefully selected value which ensures that both probes 10, 11 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. 10 The distance from the inductive probe 11 to the top of the steel cords 8 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 minus Da determines the cover thickness Dc. This simple calculation is performed by the CPU 15 12 to provide the cover thickness Dc. This value is logged in the memory 13 of a non-volatile Data Logger, along with a Date/Time Stamp. 20 Values are typically read every 250mS, while the conveyor is running. The Data Log is available for down loading either via a suitable modem 14 or the site WAN/LAN via Ethernet 15. 25 The "footprint" area of belt being measured is typically 100 x 100mm. A collision microswitch 17 is provided which activates if an object on the belt being measured comes in contact with the monitoring instrument 4 and the slotted mount 2 is forced to swing away. The "swing away" is a safety feature of the slotted 30 mount 2 which allows it to swing in the direction of belt travel, in the event of a collision. The monitoring instrument 4 has a ramped leading edge to facilitate this swing. If the collision microswitch 17 activates, the park routine is run. CAAAV ATT A large value capacitor in the power supply 18 stores enough energy to park the monitoring instrument 4 in the event of a mains power failure while deployed. 5 The slotted mount 2 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 5 is provided to confirm to the CPU 12 that the belting is positioned correctly across the 10 structure. If the belt 6 has wandered outside an operator set window, no cover thickness values are logged. Also, a signal is required to confirm the belt is running. This can be derived from a simple tacho generator 19 fitted to a local idler roller, or from the site PLC. No 15 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. 20 A further embodiment of the device has the slotted mount made to traverse the transverse member 1, 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. 25 The foregoing describes only two embodiments 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. 30 For example, 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. 51;nATAT T 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'. 5 I;AATV_ A T T

Claims

1. A method of measuring the thickness of one cover of a steel cord reinforced conveyor belt whilst the belt is moving, said method comprising the steps of: ultrasonically measuring a first distance from a known data point to the relevant surface of said belt, inductively measuring a second distance from a second known data point to the adjacent surface of the steel reinforcing cords, and subtracting said second distance from said first distance taking the distance between said known data points into account, to estimate said one cover thickness.

2. The method as claimed in claim I wherein said one cover is the carry cover of said belt.

3. The method as claimed in claim 1 wherein said one cover is the pulley cover of said belt.

4. A belt cover thickness monitoring apparatus for measuring the thickness of one cover of a steel cord reinforced conveyor belt, 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 the adjacent surface of said steel reinforcing 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 one cover thickness.

5. The cover belt thickness monitor as claimed in claim 4 wherein the two probes are mounted together in a housing movable from a retracted standby position towards said relevant belt surface to a deployed position in which each probe is operating in a substantially linear mode. 11

6. The monitor as claimed in claim 4 or 5 wherein said one cover is the carry cover of said belt.

7. The monitor as claimed in claim 4 or 5 wherein said one cover is the pulley cover of said belt

8. A belt cover thickness monitoring apparatus substantially as herein described with reference to the drawings.

9. A method for measuring the cover thickness of a steel cord reinforced conveyor belt whilst the belt is moving, said method being substantially as herein described with reference to the drawings. Dated this 9th day of August 2012 BELT WATCH PTY LIMITED By FRASER OLD & SOHN Patent Attorneys for the Applicant CnAAT7 ATT