GB2410233A

GB2410233A - Correction of lateral conveyor belt movement

Info

Publication number: GB2410233A
Application number: GB0401182A
Authority: GB
Inventors: Robert Stephen Drohan
Original assignee: Ace Conveyor Equipment Ltd
Current assignee: Ace Conveyor Equipment Ltd
Priority date: 2004-01-20
Filing date: 2004-01-20
Publication date: 2005-07-27
Also published as: GB0401182D0

Abstract

A tracking apparatus 7 for restricting lateral deviation of a moving conveyor belt comprises sensing apparatus 20 to detect the lateral deviation, and adjustment apparatus 30 to alter the orientation of the belt in response to information from the sensing apparatus, the sensing apparatus being downstream of the adjustment apparatus with respect to the direction of travel of the belt. The apparatus may be applied to the carrying run or the return run of the conveyor. The adjustment apparatus may comprise a set of idler rollers 41-43 arranged in a trough or v-formation, and may be attached to alignment apparatus 50 which may comprise a motor controlled by electronic signals from the sensing apparatus. The sensing apparatus may comprise rotatable detector rollers 23 disposed on both sides of the conveyor belt. A conveyor including the above system and a method of correcting lateral deviation of a conveyor are also claimed.

Description

1 2410233

IMPROVEMENTS IN AND RELATING TO CONVEYORS

The present invention relates to conveyors, particularly to endless belt conveyors for carrying goods and a tracking apparatus for correcting belt alignment.

It is known to employ conveyors in a number of applications for transporting goods and/or people.

Endless belt conveyors are often employed to transport goods around factories, and other industrial sites such as quarries. The belts of such conveyors are generally arranged in an endless loop having a portion running in a first general direction (carrying side of conveyor) for carrying goods from the beginning to end of a carrying run. A portion of the belt runs in a second general direction (return side of conveyor) opposed to the first general direction such that the belt has a return run to bring the belt back to the beginning of the conveying run.

Generally, such belts turn through 180 at the end of the conveying and return runs and the belt on the return run lies above or more generally below the belt on the conveying run.

The goods may comprise loose items or granular or powder materials, for example cement or coal. Belts employed to transport such goods are generally flexible both laterally and longitudinally. Over the carrying run such belts are generally supported to have a trough cross section comprising a substantially flat base, first and second side walls and an open top. Such belts are carried upon a number of idler sets. Each set typically has a centre idler roller for supporting the belt base and first and second side (wing) idler rollers inclined relative to the centre idler roller for supporting the belt sides. The idler rollers are non-driven and rotate as the belt travels over them. Typically, such belts are driven by a head, tail or end drum motor, generally by a tail drum motor located at the end of the return run where the belt changes direction to begin the conveying run.

The idler sets are arranged to define a centre path which it is desired that the belt follows.

Such belts can convey goods over a considerable distance and the belt may deviate laterally (wander) off track over the course of the conveying run. .. ë

The lateral deviation may be caused by a number of .

factors, for example, the belt may be unevenly loaded..

causing it to twist slightly. Alternatively, or in addition the idler rollers may become coated with . ..

contaminants giving them an uneven surface. This can be a particular problem when powder or granular products are transported.

If a belt deviates laterally, it consequently does not run along a central conveyor path and various problems can arise. For example, damage may be caused to the conveyor such as damage to the belt in the form of excessive wear, particularly edge wear and/or excessive wear to the idlers. Additionally, product may be spilled from the belt resulting in a poor working environment and there may be loading and/or discharge difficulties. These problems can lead to a number of further difficulties such as lost revenue due to lost material or additional stoppages, additional maintenance requirements, increased cleaning costs and risks to the health and safety of personnel.

Attempts have been made to address this problem by employing correction means to alter the orientation of the belt at one or more fixed points along the conveyor length if its lateral deviation at such a point is detected to be greater than an accepted maximum from a central position.

However, even when corrected in this manner, at positions lo along the conveyor length preceding the point of correction the belt may still have a considerable lateral deviation. Thus, though the problems discussed above may be reduced they may still be significant at least at some .

positions along the length of the conveyor.

Accordingly, the present invention aims to address at I. . least one disadvantage associated with known conveyors whether discussed herein or otherwise. . .. ..:

According to a first aspect of the present invention there is provided a tracking apparatus for restricting lateral deviation of a moving belt of a conveyor as the belt travels over at least part of the length of the conveyor, wherein the apparatus comprises sensing means to detect lateral deviation of the belt at a first location along the conveyor length and lateral adjustment means to alter the orientation of the belt at a second location along the conveyor length in response to information from the sensing means to restrict the lateral deviation at the first location and wherein said first and second locations are, in use, in spaced relationship and the second point lies upstream of the first point.

The restriction may comprise a reduction.

As used herein, the term upstream has a conventional meaning. Thus, a part of a moving belt passes an upstream point before it passes a downstream point.

The tracking apparatus may be arrangeable for restricting lateral deviation of the belt over at least part of the carrying run of the conveyor.

As used herein, the term "carrying run" means the part of the distance travelled by the belt during which it carries....

product. Suitably, the belt is endless. Suitably, at the end of the carrying run the belt has a return run to return it to the beginning of the carrying run. ..

The tracking apparatus may be arrangeable for restricting lateral deviation over at least a part of the return run ..

of the conveyor. . : As used herein, the term "return run" means the part of the distance travelled by the belt over which it travels between the end and beginning of the carrying run.

Suitably, the belt does not carry anything when travelling on the return run. Alternatively, though not normally, the belt may carry something when travelling on the return run.

Suitably, in use, said second point lies upstream of said first point by at least one metre.

Suitably, in use, the second point lies at least 2 metres, preferably at least 5 metres upstream of the first point.

Suitably, in use, the second point lies between 1 and 40 metres upstream of the first point.

Suitably, in use, the second point lies between 10 and 30 metres upstream of the first point. The second point may, in use, lie between 15 and 50 metres upstream of the first point.

lo Suitably, the sensing means communicates with the lateral adjustment means electronically. The tracking apparatus suitably comprises a control unit for interpreting signals from the sensing means and instructing the lateral adjustment means. Suitably, the sensing means is not connected to the lateral adjustment means via a moving mechanical linkage. ë

Suitably, the tracking apparatus is arranged to be . .-

employed with conveyors having a belt having a trough cross section when it travels over the conveying run.

Alternatively, the tracking apparatus may be arranged to be employed with conveyors having a belt having an alternative cross section.

Suitably, the belt is flexible both laterally and longitudinally. When unsupported the belt may lie substantially flat. Suitably, on the return run, the belt is generally supported such that it has a flat form.

Suitably, at points on the return run prone to lateral deviation and/or where lateral deviation is to be corrected the belt is supported to have a "vn form.

Suitably, on the carrying run the belt is supported to have a trough form. Thus, on the carrying run the belt may comprise a trough-cross section having a substantially flat base & first and second opposed side walls and an open top.

Suitably, the tracking apparatus is arranged to be employed with conveyors having a moving belt supported and guided by idlers.

Suitably, the belt is supported and guided by a number of lo idler sets.

Suitably, over the length of a carrying run over which product is carried by the belt the belt is supported by a ..

plurality of carrying idler sets. Suitably, each idler set comprises a number of rotatable idler rollers. ..

Suitably, the idler rollers are arranged in a "trough" '. . formation. Suitably, a centre idler roller supports and suitably guides the base of the belt. Suitably, first and..

second side (wing) idler rollers guide and suitably support first and second side walls of the belt.

Suitably, over the length of the return run the belt is supported by a plurality of return idler sets. Each idler set may comprise of one or a number of rotatable idler rollers. A return idler set may comprise first and second idler rollers arranged in a "V" formation to support the belt to have a "V" shaped cross section. This arrangement may be employed at points prone to lateral deviation, suitably the belt is guided to centre within the "V". A return idler set may comprise a single idler roller arranged to lie substantially horizontally to support the belt in a flat form. This arrangement may be used at points where lateral deviation is or would be problematic.

Suitably, in use, said second point and first point are interposed by at least one idler set. Suitably, at least two idler sets lie between the first and second point in use. Suitably, between 2 and 12 idler sets lie between the first and second point in use. Suitably, between 4 and 10 idler sets lie between the first and second point in use, preferably between 6 and 9, for example 7 or 8 when the apparatus is employed on the carrying run.

lo Suitably, between 2 and 6 idler sets lie between the first and second point, in use, for example 3 or 4 when the apparatus is employed on the return run. ....

- .e Suitably, an idler set is spaced from an adjacent idler set by between 2 and 10 metres, for example, between 2 and .

metres, for example around 3 metres. Suitably, there is I. . greater spacing on the return run. -

-.

Suitably, the lateral adjustment means of the tracking apparatus comprises guide means for guiding the direction of the belt of a conveyor with which the tracking apparatus is employed.

Suitably, the guide means of the tracking apparatus comprises an alignment idler. Preferably, the guide means comprises an alignment idler set. Suitably, the alignment idler set comprises a number of rotatable idler rollers.

Suitably, the alignment idler rollers are not directly driven and rotate as the belt travels over them.

Suitably, the rotatable idler rollers of the alignment idler set may be arranged in a "V" formation substantially the same as that of the return idler sets when the tracking apparatus is to be employed on the return run.

Suitably, the rotatable idler rollers of the alignment idler set may be arranged in a trough formation substantially the same as that of the carrying idler sets when the tracking apparatus is to be employed on the carrying run.

lo Suitably, the alignment idler set comprises a centre rotatable idler roller for supporting and suitably guiding the base of a belt of a conveyor with which the tracking apparatus is employed.

Suitably, the centre idler roller is arranged, in use, to have its axis lying in a substantially horizontal plane.

Suitably, the centre idler roller comprises a substantially cylindrical roller. Suitably, the centre idler roller has a substantially smooth surface. The centre idler roller may comprise a metal roller, for example a steel roller.

Suitably, the alignment idler set comprises a first side (wing), rotatable idler roller for guiding and suitably supporting a first side wall of a belt of a conveyor with which the tracking apparatus is employed.

Suitably, the first side idler roller is arranged, in use, to have its axis lying in a plane inclined relative to that of the centre idler roller. Suitably, the axis of the first side idler roller and centre idler roller form an angle of between 95 and 175 degrees therebetween. The first side idler roller may comprise a substantially cylindrical roller. Suitably, the first side idler roller has a grooved surface. The first side idler roller suitably has a rubber surface. The first side idler roller may comprise a metal, for example steel, roller having a rubber covering. The rubber covering may comprise a rubber coating layer or a rubber sleeve. The rubber covering may comprise a natural and/or synthetic rubber, for example black natural rubber. The rubber covering may give better friction between the idler roller lo and belt.

Suitably, the alignment idler set comprises a second side....

(wing) rotatable idler roller for guiding and suitably, supporting a second side wall of a belt of a conveyor with which the tracking apparatus is employed. ...

Suitably, the second side idler roller is arranged, in use, to have its axis lying in a plane inclined relative I to that of the centre idler roller. Suitably, the axis of . the second side idler roller and centre idler roller form an angle of between 95 and 175 degrees therebetween. The second side idler roller may comprise a substantially cylindrical roller. Suitably, the second side idler roller has a grooved surface. The second side idler roller suitably has a rubber surface. The second side idler roller may comprise a metal, for example steel, roller having a rubber covering. The rubber covering may comprise a rubber coating layer or a rubber sleeve. The rubber covering may comprise a natural and/or synthetic rubber, for example black natural rubber. The rubber covering may give better friction between the idler roller and belt.

Suitably, the alignment idler set comprises a centre idler roller and first and second side idler rollers. Suitably, the alignment idler set is arranged to have a trough formation. Suitably, the belt is supported to have a trough cross section and guided such that its lateral centre lies substantially in the centre of the trough defined by the rollers. Suitably, such an idler set is arranged to support and guide a belt of a conveyor with which the tracking apparatus is employed over part of the lo carrying run thereof.

Suitably, an alternative arrangement is employed if the apparatus is employed on the return run. Suitably, the alignment idler set comprises first and second rotatable rollers arranged in a "V" formation for supporting and guiding the belt of a conveyor. Suitably, the belt is supported to have a "V" cross-section and is guided such that its lateral centre lies substantially within the base of the "V" defined by the rollers.

The arrangement and composition of the idler rollers of the alignment idler set may be the same as that of the idler sets of the conveyor with which the tracking apparatus is employed.

Suitably, the guide means is arranged to be spaced from adjacent idler sets by approximately the same distance as idler sets are spaced from adjacent idler sets. The guide means may thus take the place of an idler set.

Suitably, the alignment apparatus can be retro-fitted to an existing conveyor. If an existing conveyor is to be modified by incorporation of a tracking apparatus according to the present invention an idler set may be replaced by guide means as described herein, preferably by an alignment idler set.

Suitably, the lateral adjustment means comprises an alignment mechanism to which the guide means are suitably connected. Suitably, the alignment mechanism allows the orientation of the guide means to be altered.

lo Suitably, the idler roller(s) of the alignment idler set are mounted to an alignment mechanism which allows the orientation of the alignment idler set to be altered. ;. ., Suitably, the guide means is arranged to guide the conveyor belt to travel in a number of directions..

depending on the orientation of the guide means as '.

determined by the alignment mechanism. ....

Suitably, a conveyor with which the tracking apparatus is employed has a centre path, suitably determined by idler sets along which the belt is desired to travel. Suitably, the centre path comprises an imaginary line joining the lateral centres of the centre rollers of adjacent idler sets. Suitably, when following the centre path the lateral centre of a length of the conveyor belt lies on this imaginary line. Suitably, the lateral adjustment means of the tracking apparatus, in use, is operable to keep the belt as close to this centre path for as much of the conveyor length as is possible.

Suitably, in response to a signal from the sensing means the guide means of the lateral adjustment means is caused to be orientated such that it guides the belt to travel in a direction as it leaves the location of the lateral adjustment means in order that there is minimal lateral deviation of the belt at the location of the sensing means. Suitably, this also causes the lateral deviation at locations between the lateral adjustment means and sensing means to be minimal.

The lateral adjustment means may be arranged to alter the lo orientation of the belt at the second location by pivoting the belt at the second location, for instance, without any lateral movement of the belt occurring at the second .

location. . .. ë

Suitably, the guide means is arranged to rotate relative..

to the centre path of the conveyor. Suitably, the axis of I. . rotation lies transverse and preferably perpendicular to the plane of the conveyor belt. Suitably, the axis of rotation extends upwardly and preferably lies substantially vertically. Suitably, when employed on the carrying run the axis of rotation lies perpendicular to the axis of the centre roller of an idler roller set comprising the guide means.

Suitably, the guide means defines a guide direction in which it directs the belt to travel. Suitably, said guide direction lies in the plane of the conveyor centre path.

Suitably, said guide direction lies perpendicular to said direction of rotation. Suitably, when employed on the carrying run said guide direction is perpendicular to the axis of the centre roller of an idler roller set comprising the guide means.

Suitably, the alignment mechanism causes rotation of the guide means in response to information from the sensing means to alter the position of the guide direction relative to the centre path of the conveyor.

Suitably, in a central position the guide direction lies along the centre path of the conveyor.

Suitably, in a left position the guide direction lies at lo an angle of up to 30 to the left side of the centre path of the conveyor.

Suitably, in a right position the guide direction lies at.

an angle of up to 30 to the right side of the centre path of the conveyor. I..:

As used herein, left and right refer to the conveyor as viewed in the direction of belt travel (i.e. from an upstream to a downstream position).

Suitably, in use, if the sensing means of the tracking apparatus determines that the belt is deviating laterally to the right then the guide means is caused to re- orientate such that the guide direction is moved towards the left. Thus, the belt may be caused to move leftward.

Suitably, in use, if the sensing means of the tracking apparatus determines that the belt is deviating laterally to the left then the guide means is caused to re-orientate such that the guide direction is moved towards the right.

Thus, the belt may be caused to move rightward.

Suitably, the alignment mechanism comprises a rotatably mounted plate on which the guide means are mounted.

Suitably, the plate is pivotally mounted about a pivot which may lie on the centre path of the conveyor. The rotatably mounted plate may be pivotally connected to a base plate which may be secured in position relative to the conveyor. The base plate may for example be bolted to part of the conveyor fixed structure.

lo Suitably the alignment mechanism comprises a motor to drive the reorientation of the guide means. Suitably, the motor is linked to the rotatably mounted plate to cause rotation thereof. Suitably, the motor is connected to the rotatably mounted plate via a linkage and shaft arrangement. I..:

Suitably, the alignment mechanism comprises limiting means.....

to prevent the guide means being rotated too far.

Suitably, the limiting means comprises limit switches arranged to cut power to the motor.

Suitably, the sensing means comprises sensors to detect lateral deviation of the conveyor belt from a centre path.

Suitably, the sensing means comprises a left sensor for positioning on a left side of the belt.

Suitably, the sensing means comprises a right sensor for positioning on a right side of the belt.

Suitably, said right and left sensors are positioned opposite one another at the same point along the conveyor length. The sensors may be mounted to the side of an idler set (a "normal" idler set). Alternatively, the sensors may be located independently of other conveyor components.

Suitably, the tracking apparatus is arranged, in use, to allow some lateral deviation of the belt from centre path before corrective alignment is made.

Suitably, the sensing means is arranged, in use, to allow lo some lateral deviation of the belt from centre path before the lateral adjustment means is signalled that the deviation should be corrected. . : :::.

Thus, the apparatus may avoid correcting minor deviations which would "self correct" and may thus avoid having to . subsequently correct deviations created by premature correction of a previous deviation by the tracking apparatus.

Suitably, the or each sensor is mounted between 1 and lOOmm from a side of the belt, for example about 25mm.

Suitably, the left and/or right, preferably each, sensor comprises a rotatable detector roller. Suitably, the left and/or right, preferably each, sensor comprises a support arm on which the rotatable detector roller is mounted.

Suitably, the rotatable detector rollers are arranged to be located adjacent the side walls of the belt. Suitably, the axis of rotation of each rotatable detector roller lies substantially vertical.

Suitably, the sensing means is arranged such that when the conveyor belt lies on its intended centre path at the sensing location both left and right sensors lie in spaced relationship to the belt.

Suitably, in use, if the belt deviates to the left it contacts the left rotatable detector roller.

Suitably, in use, if the belt deviates to the right it lo contacts the right rotatable roller.

Rotation of the detector roller caused by contact with the belt may provide a signal that the alignment of the belt should be corrected.

Preferably the or each sensor, which may include a detector roller, includes a moveable support arm and the movement of the arm provides the signal that the belt alignment should be corrected. Suitably, the support arm is movably mounted relative to a housing.

Suitably, the support arm is arranged to move between a non-detection position and one or more detection positions. Preferably, the support arm is arranged to move between a non-detection position and a single detection position. Suitably, the detection position is defined by a limit switch arranged to be actuated by the support arm when it is a predetermined distance from its non-detection position. Suitably, the support arm is biased towards the non-detection position.

Suitably, the support arm is pivotally mounted. Suitably, the support arm is caused to pivot to a detection position when the belt deviates laterally and contacts the detector roller.

Alternatively, the support arm may be slidably mounted.

The support arm may be caused to slide to a detection position when the belt deviates laterally and contacts the detector roller.

The sensing means may comprise support arms which do not lo have rollers mounted thereto and which otherwise function as defined above. However, the use of rollers is preferred as it minimises any friction caused to the belt I. - by the sensing means which may interfere with belt.'.. .

movement and alignment. .

The sensing means may comprise alternative sensors to . those described. For example, the sensing means may....

employ laser beams which are broken when the belt deviates.

laterally. However, the sensors described may provide an economical, efficient and hard wearing sensing means.

Suitably, the sensing means is arranged to provide only three output signals, namely: (i) belt deviated left; (ii) belt substantially not deviated either left or right (i.e. on centre path); and (iii) belt deviated right. The lateral adjustment means may be arranged to re-align the belt in response to signals (i) and (iii).

Alternatively, the sensing means may indicate two or more degrees of the extent of left or right deviation as defined at (i) or (ii) and the lateral adjustment means may be arranged to make different levels of realignment of the belt depending on those signals.

Suitably, the tracking apparatus comprises a control unit arranged to provide instructions to the alignment mechanism to orientate the guide means in response to signals received from the sensing means.

lo Suitably, if the sensing means detects a lateral deviation of the belt to the left the control means is arranged to instruct the guide means to be re-orientated to move the guide direction to the right. Suitably, the guide direction is rotated to the right, suitably by a predetermined angle and/or for a predetermined time. :-

The guide direction may begin to be moved to the right -.

when the sensing means detects deviation of the belt to the left and movement of the guide direction to the right may be stopped once the sensing means no longer detects deviation to the left. The guide means may remain in its re-orientated (moved) position until the sensing means detects either left or right deviation whereupon the guide means may again be re-orientated.

Suitably, if the sensing means detects a lateral deviation of the belt to the right the control means is arranged to instruct the guide means to be re-orientated to move the guide direction to the left. Suitably, the guide direction is rotated to the left, suitably by a predetermined angle and/or for a predetermined time.

The guide direction may begin to be moved to the left when the sensing means detects deviation of the belt to the right and movement of the guide direction to the left may be stopped once the sensing means no longer detects deviation to the right. The guide means may remain in its re-orientated (moved) position until the sensing means detects either right or left deviation whereupon the guide means may again be reorientated.

lo Suitably, the control means is arranged to allow an operator to adjust the predetermined angle and/or time to those most applicable to the conveyor to which the.; tracking apparatus is installed. ..

Such angles and times will depend on conveyor parameters and in particular the distance between the sensing means. and lateral adjustment means. . Suitably, the guide means is orientated by an alignment mechanism comprising a motor. Suitably, the motor runs at a constant rate and causes a predetermined rotation of the guide means for each minute of operation. Thus, it is suitably only necessary to control the time for which the motor is operated each time a belt deviation is detected in order to obtain optimum re-orientation of the guide direction. Thus, such optimization of operation may be

made by an operator in the field.

Suitably, the guide means is caused to move such that the guide direction is caused to move to the left throughout the period the right sensor detects deviation of the belt to the right. The sensor may for example detect deviation of between 1 and lOOmm. The guide direction may rotate for example through up to 18 degrees for each minute whilst deviation is detected. Alternatively, the guide direction may be caused to continue to rotate for a short period for example up to 1 minute after the sensor no longer detects deviation. Suitably, the guide means is caused to move such that the guide direction

is caused to move to the right throughout the period the left sensor detects deviation of the belt lo to the left. The sensor may for example detect deviation of between 1 and lOOmm. The guide direction may rotate for example through up to 18 degrees for each minute whilst deviation is detected. Alternatively, the guide direction may be caused to continue to rotate for a short period for example up to 1 minute after the sensor no longer detects deviation. .

Suitably, the guide means can be rotated to move the guide direction up to 30 to the left of the centre path of the conveyor. Suitably, the guide means can be rotated to move the guide direction up to 30 to the right of the centre path of the conveyor. Suitably limiting means prevent further movement. The limiting means may comprise limit switches associated with the motor of the alignment mechanism. Such switches may prevent the motor moving the guide means beyond its extreme position. The guide means can then only be moved if the belt deviates laterally in the opposite direction.

If the right sensor continues to detect lateral deviation while the guide means is at its extreme left position, a warning signal, for example an alarm, may be provided to an operator.

If the left sensor continues to detect lateral deviation while the guide means is at its extreme right position, a warning signal, for example an alarm, may be provided to an operator.

Either condition may indicate a fault requiring maintenance.

lo According to a second aspect of the present invention there is provided a conveyor comprising: (i) an endless conveyor belt; ,..

(ii) drive means for causing movement of the belt; (iii) idlers for supporting and guiding the belt; and (iv) one or more sets of tracking apparatus for restricting lateral deviation of the moving belt as the belt travels over at least part of the length of the conveyor, wherein the apparatus comprises sensing means to detect lateral deviation of the belt at a first location along the conveyor length and lateral adjustment means to alter the orientation of the belt at a second location along the conveyor length in response to information from the sensing means to restrict the lateral deviation of the belt at the first location and wherein said first and second locations are, in use, in spaced relationship and the second point lies upstream of the first point.

Suitably, the conveyor belt comprises an endless belt which may comprise segments which are assembled to produce a continuous belt.

Suitably, the belt is flexible both laterally and longitudinally. When unsupported the belt may lie substantially flat. Suitably, on the return side the belt is generally supported such that it has a flat form.

Suitably, at points on the return side prone to lateral deviation and/or where lateral deviation is to be corrected the belt is supported to have a "V" form.

Suitably, on the carrying side the belt is supported to have a trough form. Thus, on the carrying side the belt may comprise a trough-cross section having a substantially flat base & first and second side walls.

Suitably, the belt comprises of a rubber compound applied to a fabric carcass. The belt may comprise of for example a synthetic rubber compound applied to a synthetic fabric carcass.

Suitably, the conveyor is arranged to carry product.

Suitably, the conveyor has a carrying side. Suitably, the carrying side comprises the part of the conveyor which provides the carrying run (the part of the distance travelled by the belt during which it carries product).

Suitably, the conveyor has a return side. Suitably, the return side comprises the part of the conveyor which provides the return run (the part of the distance travelled by the belt during which it returns to the beginning of the carrying run).

Suitably, the conveyor extends over a length having first (tail) and second (head) ends. Suitably, the carrying run extends between the first and second end of the conveyor and the return run between the second and first end of the conveyor. Suitably, the direction of belt travel is substantially reversed at the ends of the conveyor.

Suitably, the drive means comprises of either a head, tail or end drum motor. Suitably, a tail drum motor is located at the first end of the conveyor.

Suitably, the conveyor comprises head and tail drums at either end thereof.

Suitably, the conveyor comprises a gravity take-up (G.T.U.). The gravity take-up may take up slack in and apply tension to the belt. Additionally, the gravity take-up may be employed as a storage loop for excess belt.

Suitably, the conveyor comprises idler sets for supporting and guiding the belt.

Suitably, the conveyor comprises carrying idler sets for supporting and guiding the belt on the carrying side of the conveyor. Suitably, each idler set comprises a centre rotatable idler roller and first and second rotatable side (wing) idler rollers. Suitably, the idler sets may be as described in any statement relating thereto in the first aspect.

Suitably, the conveyor comprises return idler sets for supporting and guiding the belt on the return side of the conveyor. Each idler set may comprise a single central rotatable roller. Alternatively, one or more of the idler sets may comprise two rotatable rollers arranged in a "V" formation. The V formation may be employed to help reduce lateral deviation of the belt. The V formation may tend to urge the belt to run along a centre path. Suitably, the idler sets may be as described in any statement relating thereto in the first aspect.

Suitably, the idlers are arranged to define a centre path which it is intended the lateral centre of the conveyor belt should follow. Suitably, the tracking apparatus is arranged to minimise deviation from this centre path.

lo Suitably, the conveyor comprises a set of tracking apparatus on the carrying side of the conveyor.

Suitably, the tracking apparatus is arranged such that the sensing means lies just downstream (after) a feed point at which product is fed onto the conveyor. Suitably, the sensing means lies within one metre of the feed point.

Suitably, the lateral adjustment means lies upstream (before) the feed point.

Alternatively, or in addition, a set of tracking apparatus may be located elsewhere on the carrying side. Suitably, a set of tracking apparatus is located anywhere it is anticipated or found that lateral belt deviation could be problematic.

Suitably, a number of carrying idler sets lie between the sensing means and lateral adjustment means.

Suitably, the lateral adjustment means comprises guide means located in place of a carrying idler set. Suitably, the guide means comprises an aligning idler set.

Suitably, the sensing means is mounted to a carrying idler set. Alternatively, the sensing means may be mounted on separate brackets.

The conveyor may comprise a set of tracking apparatus on the return side of the conveyor.

Suitably a set of tracking apparatus is arranged such that the sensing means lies just upstream (before) a tail drum lo (tail pulley) of the conveyor.

Alternatively, or in addition a set of tracking apparatus may be arranged such that the sensing means lies just....

upstream (before) a gravity take-up. , e e Alternatively, or in addition, a set of tracking apparatus..

may be located elsewhere on the return side. Suitably, a A. . set of tracking apparatus is located anywhere it is ..

anticipated or found that lateral belt deviation could be . .e

problematic. . : Suitably, a number of return idler sets lie between the sensing means and lateral adjustment means.

Suitably, the lateral adjustment means comprises guide means located in place of a return idler set. Suitably, the guide means comprises an aligning idler set.

Suitably, the sensing means is mounted to a return idler set. Alternatively, the sensing means may be mounted on separate brackets.

Suitably, the tracking apparatus comprises a tracking apparatus according to the first aspect.

Suitably, the conveyor may be as described in any

statement relating thereto in the first aspect.

According to a third aspect there is provided a method of restricting lateral deviation of the belt of a conveyor as the belt travels over at least part of the length of the lo conveyor, wherein the method comprises: (i) detecting lateral deviation of the belt at a first location; and (ii) altering the orientation of the belt at a second, location to restrict the lateral deviation of the belt at, the first location, said second location being in spaced relationship to said first location and upstream thereof. . Suitably, the method employs a tracking apparatus ., . according to the first aspect.

The present invention will now be described by way of '... : example with reference to the accompanying drawings in which: Figure 1 is a perspective view of part of a conveyor; Figure 2 is an isometric view of an aligning apparatus showing hidden detail; Figure 3 is a front elevation of the aligning apparatus showing hidden detail; Figure 4 is a plan view of the aligning apparatus showing hidden detail; and Figure 5 is a side view of the aligning apparatus showing hidden detail.

As illustrated by Figure 1 a conveyor 1 comprises an endless belt 10 (part shown). The conveyor 1 comprises first (tail) and second (head) ends la, lb between which the belt 10 extends. The belt 10 is supported by head and tail drums 3, 2, at either end where it changes its direction of travel. The conveyor 1 has a carrying side 11 providing a carrying run over which product 4 is carried by the belt 10 in a downstream direction (illustrated by arrow A). Product 4 is fed onto the conveyor at a feed point 5.

The belt 10 is driven by a tail drum motor (not shown) connected to tail drum 2 at the fist end la of the conveyor 1. ë-

- :::.

The conveyor 1 has a return side 12 providing a return run over which the belt 10 returns from the second end lb to the first end la.

The belt 10 comprises a synthetic rubber compound applied to a synthetic fabric carcass and is flexible both longitudinally and laterally. When unsupported the belt may lie substantially flat. On the return side 12 the belt 10 is generally supported such that it has a flat form. At points prone to lateral deviation or where lateral deviation is to be corrected it is supported to have a "V" form (not shown). On the carrying side the belt 10 is supported to have a trough form. Thus, on the carrying side the belt 10 has a trough cross-section having a substantially flat base 13 and first and second side walls 14, 15.

Along the carrying side the belt 10 is supported and guided by carrying idler sets 6. The carrying idler sets 6 each comprise a rotatable centre idler roller (not shown) for guiding and supporting the belt base 13 and rotatable side (wing) idler rollers 6a, 6b for guiding and supporting the side walls 14, 15 of the belt 10.

Along the return side 12 the belt 10 is supported and guided by return idler sets (not shown). The return idler sets generally comprise a single roller to support the belt 10 to run flat. However, at points prone to lateral deviation the idler sets comprise two rollers arranged to form a "V" such that they support the belt to have a "V" ..

cross section. 2', . . The conveyor further comprises alignment apparatus 7 for restricting lateral deviation of the belt 10 along a part of the carrying side 11. The alignment apparatus 7 comprises sensing means 20 comprising left and right sensors 21, 22 and lateral adjustment means 30 comprising guide means 40.

The belt 10 is intended to run along a conveyor centre path (illustrated by dotted line B) defined by the idler sets 6. The guide means is arranged to rotate left (illustrated by arrow L) or right (illustrated by arrow R) to correct lateral deviation of the belt 10 and keep the lateral centre of the belt 10 as close as possible to the conveyor centre path.

The guide means 40 takes the place of a carrying idler set 6 and is spaced several idler sets, 7 sets in the illustrated embodiment (approximately 20 metres), upstream of the sensing means 20. The sensing means 20 is mounted to a carrying idler set just downstream of the feed point 5. In the embodiment shown the sensing means 20 is mounted just upstream of the idler rollers of the idler set 6 but it may be mounted downstream thereof.

lo The tracking apparatus further comprises a control unit 60 in communication with the sensing means 20 and lateral adjustment means 30. The control means 60 comprises a control box 61 mounted at one side of the conveyor where -- there is good access. The control box comprises a power supply, a motor junction box, limit switch jumper boxes and the control circuit of the apparatus. The control..

apparatus is arranged to instruct the guide means 40 to.

rotate left if the right sensor 22 is activated and to rotate right if the left sensor 21 is activated. .. .

The tracking apparatus is best illustrated by Figures 2 to 5.

The lateral adjustment means 30 comprise a guide means 30 which comprises an alignment idler set. The idler set comprises a "roughed idler set having a rotatable centre idler roller 41 for supporting and guiding the belt base 13. The set further comprises first and second rotatable side (wing) idler rollers 42, 43 having grooved rubber coverings, for supporting and guiding the belt side walls.

The side idler rollers 42, 43 are rubber covered so that there is greater friction between the idler set and the conveyor belt 10. Hence, when the guide means is operating to direct the belt 10 back towards a centre path there will be minimal slippage between the belt 10 and side idler rollers 42, 43.

The rotatable rollers 41, 42, 43 are connected to a plate 51 which in turn is connected to base plate 52 via a pivot device 53. Plate 51 is thus rotatable. The base plate 52 bolts to the conveyor structure 1 just as a known "roughed idler set would be bolted to the conveyor structure 1.

Plates 51, 52 and pivot device 53 comprise part of an alignment mechanism 50 arranged to adjust the orientation of the guide means 40.

The alignment mechanism 50 further comprises a motor 54 which is mounted to a support plate 55. The motor is connected via a lever arrangement 56 and shaft 57 to the rotatable plate 51 carrying the guide means 30. The'.. . alignment mechanism is arranged such that rotation of the motor in either direction causes the lever arrangement 56 (whose movement follows the path of a sine curve) and shaft 57 to transfer a rotational motion to the guide means. Depending on the motor direction this will either be to the left or right (relative to the downstream direction & centre path). The motor is caused to move the guide means in response to a signal from the left or right sensor 21, 22. Also mounted to the support plate 55 are heavy duty limit switches 58, 59 which are arranged to prevent the motor 54 operating to turn the guide means 40 beyond a given extreme to the left or right. Once a switch is actuated the motor 54 is switched off and can then only operate to turn the guide means 40 away from its extreme position. Thus, the motor 54 can only be re- activated when the sensor 21, 22 which was not previously activated is activated. The limit switches are actuated when hit by a rod attached to the lever arrangement 56.

The sensing means 20 comprises two sensors 21, 22 as mentioned. Each sensor comprises a rotatable roller 23 mounted to a support arm 24. Each support arm 24 is pivotally connected to a housing 25 and linked to a limit switch (not shown). The sensors 21, 22 are spaced approximately 25mm from the edge of the belt 10 when the belt is running on the centre path. Thus, the belt may make slight lateral deviations before the sensors are activated. If the belt 10 deviates substantially laterally it knocks a sensor 21, 22. The roller 23 of the sensor then rotates so as not to cause excessive drag on the belt 10. The support arm 24 of the sensor then pivots away from the belt 10 and as lateral deviation of the belt continues it actuates a limit switch. The actuation oft.. . the limit switch causes a signal to be sent to a control unit 60 that the belt requires re-alignment. The control unit in turn provides the appropriate instruction to the alignment mechanism 50 to re-orientate the guide means 30.

Once the belt 10 is re-aligned and runs substantially on the centre path as it passes the sensor the sensor returns to its starting position.

In an alternative embodiment (not illustrated) each sensor may comprise two or more limit switches arranged to be actuated at different degrees of pivoting of the sensor arm. The greater the degree of lateral deviation of the belt the greater number of switches will be actuated and the control means will receive a different signal and instruct the alignment mechanism to re-orientate the guide means by a greater amount accordingly.

In use, the guide means is arranged to provide a guide direction (illustrated by arrow C) in which it guides the belt to travel. In a central orientation of the guide means the guide line lies along the centre path of the conveyor (illustrated by arrow B) which is the imaginary line that it is desired the lateral centre of the belt should follow.

lo If the sensing means 20 detects that the belt has deviated laterally to the left, i.e. the left sensor 21 provides a signal then the guide means 40 is rotated to the right (shown by arrow R) by the alignment mechanism 50 to move....

the guide direction to an angle right of its previous direction.

If the sensing means 20 detects that the belt has deviated''. . laterally to the right, i.e. the right sensor 21 provides a signal then the guide means 40 is rotated to the left .

(shown by arrow L) by the alignment mechanism 50 to move the guide direction to an angle left of its previous direction.

With the guide direction altered the belt is caused to travel such that when it reaches the location of the sensing means 20 it lies substantially on the centre path.

Suitably, when the belt is aligned in this manner the belt also lies substantially on the centre path while travelling between the lateral adjustment means 30 and the sensing means 20. Lateral deviation of the belt may thus be minimized.

If the belt 10 subsequently deviates to the left or right the guide means 40 can be re-orientated accordingly.

However, if the guide means 40 is already in an extreme right or left position then it can only move away from that position. If the guide means 40 remains in an extreme position for prolonged periods then the conveyor may require maintenance and/or corrective action by an operator. However, it will be appreciated that the tracking apparatus of the present invention may generally lo reduce the need for maintenance and/or corrective action by an operator in order to ensure that the belt remains laterally aligned.

Attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and ..

which are open to public inspection with this'.. . specification, and the contents of all such papers and documents are incorporated herein by reference. .'

All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

Each feature disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel combination, of the features

disclosed in this specification (including any

accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any lo method or process so disclosed. - - -

- . . * .. . . . -

Claims

Claims 1. A tracking apparatus for restricting lateral deviation of a

moving belt of a conveyor as the belt travels over at least part of the length of the conveyor, wherein the apparatus comprises sensing means to detect lateral deviation of the belt at a first location along the conveyor length and lateral adjustment means to alter the orientation of the belt lo at a second location along the conveyor length in response to information from the sensing means to restrict the lateral deviation at the first location and wherein said first and second locations are, in use, in spaced relationship and the second lies upstream of the first.
2. A tracking apparatus according to Claim 1, wherein the apparatus is arrangeable for restricting lateral deviation of the belt over at least part of the carrying run of the conveyor.
3. A tracking apparatus according to Claim 1, wherein the apparatus is arrangeable for restricting lateral deviation of the belt over at least a part of the return run of the conveyor.
4. A tracking apparatus according to any preceding claim, wherein the sensing means communicates with the lateral adjustment means electronically.
5. A tracking apparatus according to any preceding claim, wherein the apparatus is arranged to be employed with conveyors having a moving belt supported and guided by idlers.
6. A tracking apparatus according to any previous claim, wherein the lateral adjustment means comprises guide means for guiding the direction of the belt of a conveyor.
7. A tracking apparatus according to any preceding claim, lo wherein the lateral adjustment means of the tracking apparatus comprises guide means comprising an alignment idler set for guiding the direction of the belt of a conveyor with which the tracking apparatus is employed.
8. A tracking apparatus according to Claim 7, wherein the alignment idler set comprises rotatable idler rollers arranged in a trough formation substantially the same as that of a carrying idler set when the tracking apparatus is to be employed on the carrying run of the conveyor.
9. A tracking apparatus according to Claim 7, wherein the alignment idler set comprises rotatable idler rollers arranged in a "V" formation substantially the same as that of a return idler set when the tracking apparatus is to be employed on the return run of the conveyor.
10. A tracking apparatus according to any one of Claims 6 to 9, wherein the lateral adjustment means comprises an alignment mechanism to which the guide means are suitably connected and which allows the orientation of the guide means to be altered.
11. A tracking apparatus according to Claim 10, wherein the alignment mechanism comprises a motor to drive the re-orientation of the guide means.
12. A tracking apparatus according to Claim 10 or 11, wherein the guide means defines a guide direction in which it directs the belt to travel and the alignment mechanism is arranged to cause rotation of the guide lo means in response to information from the sensing means to alter the position of the guide direction relative to the centre path of the conveyor.
13. A tracking apparatus according to Claim 12, wherein the alignment mechanism comprises limiting means to prevent the guide means being rotated too far.
14. A tracking apparatus according to any of Claims 6 to 13, wherein, in use, if the sensing means of the tracking apparatus determines that the belt is deviating laterally to the right then the guide means is caused to re-orientate such that the guide direction is moved towards the left and if the sensing means of the tracking apparatus determines that the belt is deviating laterally to the left then the guide means is caused to re-orientate such that the guide direction is moved towards the right.
15. A tracking apparatus according to any preceding claim, wherein the sensing means comprises sensors to detect lateral deviation of the conveyor belt from a centre path.
16. A tracking apparatus according to Claim 15, wherein the sensing means comprises a left sensor for positioning on a left side of the belt and a right sensor for positioning on a right side of the belt.
17. A tracking apparatus according to Claim 16, wherein the left and/or right sensor comprises a rotatable detector roller.

lo
18. A tracking apparatus according to Claim 17, wherein the left and/or right sensor comprises a support arm on which the rotatable detector roller is mounted.
19. A tracking apparatus according to any preceding claim, wherein, the apparatus is arranged, in use, to allow some lateral deviation of the belt from centre path before corrective alignment is made.
20. A tracking apparatus substantially as herein described with reference to the accompanying drawings.
21. A conveyor comprising: (i) an endless conveyor belt; (ii) drive means for causing movement of the belt; (iii) idlers for supporting and guiding the belt; and (iv) one or more sets of tracking apparatus for restricting lateral deviation of the moving belt as the belt travels over at least part of the length of the conveyor, wherein the apparatus comprises sensing means to detect lateral deviation of the belt at a first location along the conveyor length and lateral 3q adjustment means to alter the orientation of the belt at a second location along the conveyor length in response to information from the sensing means to restrict the lateral deviation of the belt at the first location and wherein said first and second locations are, in use, in spaced relationship and the second point lies upstream of the first point.

lo
22. A conveyor according to Claim 21, wherein the conveyor comprises a set of tracking apparatus on the carrying side of the conveyor.
23. A conveyor according to Claim 22, wherein the tracking apparatus is arranged such that the sensing means lies just downstream of (after) a feed point at which product is fed onto the conveyor.
24. A conveyor according to Claim 23, wherein the lateral adjustment means lies upstream of (before) the feed point.
25. A conveyor according to Claim 22 or 23, wherein the lateral adjustment means comprises guide means located in place of a carrying idler set and which comprises an aligning idler set.
26. A conveyor according to Claim 21, wherein the conveyor comprises a set of tracking apparatus on the return side of the conveyor.
27. A conveyor according to Claim 26, wherein the lateral adjustment means comprises guide means located in place of a return idler set.
28. A conveyor according to any of Claims 21 to 27, wherein the tracking apparatus comprises a tracking apparatus according to any of Claims 1 to 20.
29. A conveyor substantially described herein with lo reference to the accompanying drawings.
30. A method of restricting lateral deviation of the belt of a conveyor as the belt travels over at least part of the length of the conveyor, wherein the method comprises: (i) detecting lateral deviation of the belt at a first location; and (ii) altering the orientation of the belt at a second location to restrict the lateral deviation of the belt at the first location, said second location being in spaced relationship to said first location and upstream thereof.
31. A method according to Claim 30, wherein the method employs a tracking apparatus according to any of Claims 1 to 20.
32. A method according to Claim 30, wherein the method employs a conveyor according to any of Claims 21 to 29.