AU658285B2 - Conveyor belt weighing device and method - Google Patents

Description

Our Ref: 465921 658285 P/00/011 Regulation 3:2

AUSTRALIA

Patents Act 1990

ORIGINAL

COMPLETE SPECIFICATION STANDARD PATENT

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Applicant(s): Address for Service: Invention Title: Control Systems Technology Pty Ltd Unit 8/62 Blackshaw Avenue MORTDALE NSW 2223

AUSTRALIA

DAVIES COLLISON CAVE Patent Trade Mark Attorneys Level 10, 10 Barrack Street SYDNEY NSW 2000 Conveyor belt weighing device and method The following statement is a full description of this invention, including the best method of performing it known to me:- 5020 AMO/0530a CONVEYOR BELT WEIGHING DEVICE AND METHOD The present invention relates to a conveyor belt weighing device and method, and in particular, to a conveyor belt weighing device and method which, provides a indication of the weight of the load on a conveyor belt as a function of the speed or linear .movement of said conveyor belt.

Conveyor belts are presently utilised in a wide variety of applications, including in the mining and manufacturing industries. To weigh material transferred by means of a conveyor belt, it is already known to provide weighing devices or load cells at spaced apart locations along the length of the conveyor belt, attached to the conveyor belt frame or stringer for the purpose of measuring displacement between the idlers supporting the conveyor belt and the frame or stringer.

The present invention therefore seeks to provide a conveyor belt weighing device and which may be used either in conjunction with known weighing devices/methods to provide an improved weighing device and method, or in place eeoc oo thereof.

The present invention seeks to provide a conveyor belt weighing device and method which provides an indication of e the weight of the load on or which has passed over the conveyor belt, as a function of the speed or linear movement of the conveyor belt.

eee@ In one brcid form, the present invention provides a conveyor belt weighing device, comprising: a tachometer wheel, the circumferential edge of which is in intimate or tangential contact with the underside of the conveyor belt; sensor means to measure the speed or movement of said tachometer wheel and provide a signal representative of the speed or linea; movement of said conveyor belt; and, processing means to process said conveyor belt speed or linear movement signal, and to provide an indication of the load weight or flow rate of a load carried on said conveyor AMD/0530a -2belt, said processing means utilising a predetermined relationship between the speed or movement or circumference of said wheel and the weight of said load on said belt to calculate said load weight or flow rate of said load.

The present invention may, in one preferred form be used in conjunction with another known weight indication device or method, or, in an alternative preferred form, be used on its own.

Preferably, said tachometer wheel is manufactured to a predetermined accuracy, such that a substantially accurate relationship is established between the circumferential length of said wheel and the speed or linear movement of said conveyor belt.

Also preferably, cleaning means is provided on said tachometer wheel to maintain said circumferential edge in a pristine condition.

In a preferred form of the invention, said processing means is provided with or calculates an updated predetermined relationship during operation of said device to compensate for wear of said wheel.

In a preferred embodiment, at least one groove or slot is provided along said circumferential edge such that when said edge has worn to the depth of said groove(s) or slot(s), said wheel and/or said predetermined relationship may be changed.

In addition, said processing means is preferably embodied to automatically monitor the wear of said wheel and oooe update said predetermined relationship.

oeoe A preferred implementation of the sensor means is to use a magnetic induction sensor to determine revolutions of the tachometer wheel.

An alternative preferred implementation of the sensor means is wherein said sensor means comprises an LED and a detector, and wherein said wheel is provided with slots or openings therein, such that as said wheel rotates, pulses are received by said de'tector.

In a further broad form the present invention provides a method of monitoring the weight of a load on a conveyor belt, comprising the steps of: 'AMD/0530a 3 monitoring the movement of a conveyor belt utilising a tachometer wheel and sensor means to provide a signal representative of the speed or linear movement of said conveyor belt; and processing said signal to provide a display indicative of the load on said conveyor belt utilising a predetermined relationship between the speed or movement of said wheel and the flow rate or weight of said load on said belt to calculate said load weight.

Preferably, to establish said predetermined relationship between the circumferential length of said wheel and the speed or linear movement of said conveyor belt, said tachometer wheel is manufactured to a predetermined accuracy.

Also preferably, in said processing step, means for calculating an updated predetermined relationship during operation of said device, to compensate for wear of said wheel, is provided.

Also preferably, in said processing step, means for automatically monitoring the wear of said wheel and updating said predetermined relationship, is provided.

The present invention will become more fully understood from the following detailed description of a preferred by non-limiting embodiment thereof, in connection with the accompanying drawings, wherein: Fig. 1 illustrates a plan view of the conveyor belt weighing device in accordance with the present invention; Fig. 2 illustrates an elevational view of the device illustrated in Fig. 1; and, Fig. 3 illustrates a cross-sectional view through lines A-A of Fig. 2.

The conveyor belt weighing device, generally designated by the numeral i, is basically attached to the underside of the conveyor belt 2. The conveyor belt may be any conventional type of conveyor belt supported by idlers such as illustrated most clearly in Fig. 3 having a central idler 3 and side idlers 4, the idlers being supported on a frame 'AMD/0530a 4 in a conventional manner. The device 1 essentially comprises a tachometer wheel 6 supported on an axis 7 for rotation thereabouts. Rotation of the wheel 6 is effected by contact of the circumferential edge 8 on the underside of the belt 2. That is, as the belt 2 moves along, the tachometer wheel 6 is rotated about axis 7. It is the speed or linear movement of the tachometer wheel 6 which is then monitored by the sensor 9. The sensor 9 may be any conventional sensor which is utilised to determine the speed of the rotating wheel, and may for example be embodied as a magnetic induction sensor or by an LED emitting a light through slots or grooves in the tachometer wheel 6 such that pulsations of the emitted light are received by a detector provided on the opposed side of the tacho wheel 6. It will however be appreciated that many other forms of sensor to sense the speed or linear movement of the wheel are possible and are known to persons skilled in the art.

Obviously during loading of the conveyor belt, the ***conveyor belt may be displaced in the vertical direction.

ooee To allow for such displacement to occur, the tacho wheel axis is preferably provided on an adjustable pivot perhaps best illustrated in Fig. 2, to allow upward and downward movement of the tacho wheel assembly. This adjustable pivot may for instance be embodied as a rod which allows vertical movement of the assembly therealong, biased to a normal position by springs or the like.

It will be appreciated that in use, the tachometer oeoo wheel circumferential edge is -in contact with the conveyor ooee belt and rotates as the conveyor belt moves along its path.

The sensor means will then measure the speed or linear movement of the tachometer wheel and provide a signal representative of the speed or linear movement of the conveyor belt. Processing means can then be utilised to process the conveyor belt speed or linear movement signal and provide a display indicative of the weight of a load on the conveyor belt. The processing means is preferably provided with a predetermined functional relationship between the speed of the wheel and the weight of a load placed on the conveyor belt, and utilising this 'AMD/0530a 5 predetermined relationship, the processing means can calculate the instantaneous load weight.

It will be appreciated that the tachometer wheel therefore has to be manufactured to a high degree of accuracy such that a substantially accurate relationship is established between the circumferential length of the wheel and the speed or linear movement of the conveyor belt. It would be appreciated that the wheel may become dirty, or may wear, and that this has to also be taken into account to ensure that the conveyor belt weighing device and method of the invention is maintained accurate. The wheel may be self-cleaning, effected by the presence of the belt thereon, however, if not, some form of cleaning means may be provided to contact the tachometer wheel edge to ensure that dirt is not attached to the edge of the conveyor belt which would then render the device inaccurate. In relation to the problem of the tachometer wearing, it is proposed that one or more slots or grooves could be provided in the edge of the wheel, and the wearing of the edge of the wheel could be monitored to see when it has worn down to the depth of the slot or groove. This could either be done by an operator, or could be monitored electrooptically by the processing means. Once the edge is worn down, either the wheel could replaced, or the predetermined functional relationship between the speed and the weight could be altered to take this wearing of the edge into account. Once again, this could be conducted automatically by the processing means, or could be manually effected by an operator. Other ways-of monitoring the wear of the tacho wheel and providing appropriate compensation for such wear will become apparent to persons skilled in the art, such that a highly accurate device is maintained.

It will be appreciated that wheels of varying width may be embodied. Obviously, wider wheels will display less wearing on their edges.

It will also be appreciated that the device may be utilised on its own or in conjunction with conventional weight indication devices. It will also be understood that the device should preferably be placed adjacent a support 'AMD/0530a 6 (eg. idler) such that belt stretch is eliminated.

It will be appreciated that numerous other variations and modifications to the invention will be envisaged to persons skilled in the art. All such variations and modifications should be considered to fall within the scope of the invention as broadly described hereinbefore as claimed hereinafter.

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Claims (14)

1. A conveyor belt weighing device, comprising: a tachometer wheel, the circumferential edge of which is in intimate or tangential contact with the underside of the conveyor belt; sensor means to measure the speed or movement of said tachometer wheel and provide a signal representative of the speed or linear movement of said conveyor belt; and, processing means to process said conveyor belt speed or linear movement signal, and to provide an indication of the load weight or flow rate of a load carried on said conveyor belt, said processing means utilising a predetermined relationship between the speed or movement or circumference I° .of said wheel and the weight of said load on said belt to calculate said load weight or flow rate of said load.

2. A conveyor belt weighing device as claimed in claim i, wherein said tachometer wheel is manufactured to a predetermined accuracy, such that a substantially accurate relationship is established between the circumferential o length of said wheel and the speed or linear movement of said conveyor belt.

3. A conveyor belt weighing device as claimed in claims 1 or 2, wherein cleaning means is provided on said tachometer wheel to maintain said circumferential edge in a pristine 4 condition.

4. A conveyor belt weighing device as claimed in any one of claims 1 to 3, wherein said processing means is provided o. ~wi-th or calculates an updated predetermined relationship during operation of said device to compensate for wear of said wheel.

A conveyor belt weighing device as claimed in any one of claims 1 to 4, wherein at least one groove or slot is provided along said circumferential edge such that when said edge has worn to the depth of said groove(s) or slot(s), said wheel and/or said predetermined relationship may be changed.

6. A conveyor belt weighing device as claimed in any one of claims 1 to 5 wherein, said processing means automatically monitors the wear of said wheel and updates AMD/0530a 8 said predetermined relationship.

7. A conveyor belt weighing device as claimed in any one of claim 1 to 6, wherein said sensor uieans is comprised of a magnetic indication sensor to determine the revolution of said tachometer wheel.

8. A conveyor belt weighing device as claimed in any one of claims 1 to 6, wherein said sensor means comprises an LED and a detector, and wherein said wheel is provided with slots or openings therein, such that as said wheel rotates, pulses are received by said detector.

9. A method of monitoring the weight or flow rate of a load on a conveyor belt, comprising the steps of: monitoring the movement of a conveyor belt utilising a tachometer wheel and sensor means to provide a signal representative of the speed or linear movement of said conveyor belt; and processing said signal to provide an indication of the weight or flow rate of the load on said conveyor belt #see. utilising a predetermined relationship between the speed or e movement or circumference of said wheel and the flow rate or weight of said load on said belt to calculate said load r weight.

A method of monitoring the weight or flow rate of a load on a conveyor belt as claimed in claim 9, wherein, to establish said predetermined relationship between the circumferential length of said wheel and the speed or linear movement of said conveyor belt, said tachometer wheel is 4. manufactured to a predetermined accuracy.

11. A method of monitoring the weight or flow rate of a load on a conveyor belt as claimed in claims 9 or o. wherein, in said processing step, means for calculating an updated predetermined relationship during operation of said device, to compensate for wear of said wheel, is provided.

12. A method of monitoring the weight or flow rate of a load on a conveyor belt as claimed in any one of claims 9 to 11, wherein, in said processing step, means for automatically monitoring the wear of said wheel and updating said predetermined relationship, is provided.

13. A conveyor belt weighing device, substantially as AMD/0530a ABSTRACT A conveyor belt weighing device comprising: a tachometer wheel the circumferential edge of which is in intimate or tangential contact with the underside of the conveyor belt sensor means to measure the speed or movement of said tachometer wheel and provide a signal representative of the speed or linear movement of said conveyor belt and, processing means to process said conveyor belt speed or linear movement signal, and to provide an indication of the load weight o- flow rate of a load carried on said conveyor belt said processing means utilising a predetermined relationship between the speed or movement or circumference of said wheel and the weight of said load on said belt to calculate said load weight or flow rate of said load. Fig. 3 o* *o e oo AMD/0530a -9- herein described with reference to the accompanying drawings,

14. A method of monitoring the weight of a load on a conveyor belt, substantially as herein described in relation to the accompanying drawings. DATED this 7th day of April, 1993. CONTROL SYSTEMS TECHNOLOGY PTY LTD By Its Patent Attorneys DAVIES COLLISON CAVE a. a. a a. p a aL a 0*aO a aria