AU728890B2

AU728890B2 - Tracking assembly for trough conveyor belts

Info

Publication number: AU728890B2
Application number: AU78774/98A
Authority: AU
Inventors: John Pear Cumberlege
Original assignee: Tru Trac Rollers Pty Ltd
Current assignee: TRU-TRAC ROLLERS Pty Ltd
Priority date: 1997-08-04
Filing date: 1998-08-04
Publication date: 2001-01-18
Anticipated expiration: 2018-08-04
Also published as: AU7877498A

Description

P/00/01 1 Regulation 3.2

AUSTRALIA

Patents Act 1990

ORIGINAL

COMPLETE SPECIFICATION STANDARD PATENT Invention Title: Tracking assembly for trough conveyor belts The following statement is a full description of this invention, including the best method of performing it known to us:

S

S S FHiP.S V DCE.N ATE 1205)112 1(012.1 ICA98216(A5.9 1 TRACKING ASSEMBLY FOR TROUGH CONVEYOR BELTS Field of the invention This invention relates to a conveyor belt tracking assembly and, more particularly, a tracking assembly for a trough shaped conveyor belt.

Background of the invention It is well known in the conveyor industry that keeping a conveyor belt tracking centrally, that is, moving alone its intended centralised travel path is not always easily achievable. Generally, when a conveyor assembly is first set up the installer will ensure that the belt travels centrally.

However, it often happens that the belt begins to track or travel off-centre and some form of tracking roller or assembly is required in order to bring the belt back to its central position.

The problem is exacerbated where the belt becomes old or worn or carries materials which adhere to the load carrying face of the belt such as is often the case in the mining industry.

Mined mineral is often dumped onto a travelling conveyor belt and this material tends to cut and tear the belt requiring the belt to be spliced from time to time and splicing tends to result in a belt which is not completely straight and this results in the belt tracking off-centre.

There have been many attempts made to solve the tracking problem of conveyor belts. Most of 0% 0 these tracking systems employ a roller which is mounted in some form of cradle or sub-frame which is able to pivot relative to the frame on which the tracking assembly is mounted. As the belt travels off-centre, the edge of the belt contracts some form of guide roller adjacent to the 20 tracking assembly and, provided the edge contact is sufficiently hard or direct this will force the cradle to adopt a skew position and steer the belt back to its central position. Examples of the aforementioned types of systems are described in US patent 2,815,851; US patent no.

2,109,923; US patent no. 1,963,099; US patent no. 2,609,084; US patent no. 2,570,364, and like 0 documents.

Many of these prior art arrangements suffer from a problem in that a significant force must be exerted by the edge of the belt onto a guide roller at the side of the assembly in order to cause the sub-frame or cradle to pivot relative to its support arrangement. This tends to cause damage to the edge of the belt and damage to the guide rollers. Also, as the cradle sloughs the guide rollers tend to cut into the belt path so the belt actually reacts against the cradle moving into a sloughed position. The efficacy of the tracking action is thus significantly reduced.

ItCA9821I 615.9 2 Summary of the invention According to the invention there is provided a tracking assembly for tracking the trough side of an endless conveyor belt which travels on a conveyor structure, the tracking assembly comprising: a cross bar which extends across the width of the conveyor structure and is adapted to be mounted to the structure at the opposite ends of the bar with the bar substantially perpendicular to the direction of travel of the belt; a sleeve which encloses a central portion of the cross bar; a pivot arrangement connecting the sleeve to the cross bar, the pivot arrangement defining a pivot axis about which the sleeve is pivotable relative to the cross bar, the pivot axis being substantially perpendicular to the central portion of a belt which rides on the assembly in use; a roller co-axially mounted to the sleeve and rotatable relative to the sleeve on a pair of bearing assemblies spaced apart on opposite sides of the pivot axis; and a pair of wing rollers mounted to opposite ends of the sleeve and extending upwardly from the cross bar in a substantially vertical plane, each wing roller being angled outwardly in an upward direction at an angle of between 250 and 85' to the horizontal.

Further there is provided for the plane in which the wing rollers are located to be parallel to but spaced apart from the cross bar. The wing rollers are preferably located on the leading side of 20 the cross bar.

The angle at which the wing rollers are aligned relative to the horizontal is preferably greater than the trough angle of the conveyor belt. The wing rollers are preferably spaced apart from each other by a distance which is greater than the effective width of the belt so that when the belt is centralised the edges of the belt do not contact either of the wing rollers.

The wing rollers are preferably mounted to a tie bar which is mounted to the sleeve via a pair of extension arms fixed to the opposite ends of the sleeve, the tie bar being parallel to the sleeve axis. Preferably the wing rollers are adjustably mounted relative to the tie bar and securable in different positions of adjustment to provide means for adjusting the distance between the wing rollers. The angle of the wing rollers relative to the horizontal may be variable.

CA98216(X)5.9 3 It is envisaged that, when the belt is in its central position, the edges of the belt will be spaced way from the wing rollers by between about lcm and l0cms. Of course, for different belt widths and sensitivity requirements different arrangements will be possible.

These and further features of the invention will be made apparent from the description of two embodiments of the invention given below by way of examples. In the description reference is made to the accompanying drawings but specific features shown in the drawings should not be construed as limiting on the invention.

Brief description of the drawings Figure 1 shows a perspective view of a first embodiment of the invention; Figure 2 shows a plan view of the tracking assembly shown in Figure 1; Figure 3 shows an end view of the tracking assembly shown in Figure 1; Figure 4 shows a perspective view of a second embodiment of the tracking assembly according to the invention; and Figure 5 shows a plan view of the assembly shown in Figure 4.

Detailed description of the embodiments It will be understood that the invention disclosed and defined herein extends to all alternative combinations of two or more of the individual features mentioned or evident from the text or drawings. All of these different combinations constitute various alternative aspects of the invention.

The foregoing describes embodiments of the present invention and modifications, obvious to those skilled in the art can be made thereto, without departing from the scope of the present invention.

As shown in Figures 1 to 3 of the drawings, a tracking assembly 10 is specifically adapted for tracking a trough shaped conveyor belt. The assembly comprises a cross bar 12 having o 25 mounting brackets 14 on opposite ends thereof for -mounting to a conveyor frame or structure (not shown). The cross bar 12 is mountable tothe feet 14 by means of tubular mounting sleeves 16 which are mounted to the cross bar by grub screws 18. The tubular mounting sleeves 16 are slidable along the length of the cross bar 12 so that the width of the assembly can be adjusted for mounted to different width conveyor frames.

SCA98216M05.9 4 A sleeve 20 is pivotally mounted to the cross bar 12 so as to pivot about a pivot axis 22 which is substantially vertical, that is, perpendicular to a belt 24 which rides on the assembly. The arrangement of the belt is best seen in Figure 3 of the drawings.

The sleeve is mounted to the cross bar in an arrangement similar to that described in Australian patent serial no. 685005, the specification of that patent being incorporated herein in its entirety by way of reference. The sleeve 20 is thus non-rotatably mounted to the cross bar 12. A roller 26 is co-axially mounted on the sleeve 20 via bearing assemblies so as to be rotatable relative to the sleeve 20. The roller 26 is a central roller, that is, the centre of the roller 26 will lie substantially on the centre line of the conveyor belt when the belt is travelling centrally.

A pair of horizontal extension arms 28 are mounted i .oppose ends of the sleeve 20 and these arms 28 are tied together by a tie bar 30. A pair of wing rollers 32a and 32b are mounted to the tier bar 30 by means of an adjustable mounting arrangement 34. Each adjustable mounting arrangement 34 comprises a pair of rectangular straps 36 through which a rectangular support bar 38 passes and is held in position by a pair of grub screws 40. This mounting arrangement allows the position of the wing rollers, relative to the centre line of the conveyor frame to be adjusted inwardly or outwardly to allow for different conveyor belt configurations.

As mentioned above, the sleeve 20 is able to pivot relative to the cross bar 12 about pivot axis 22, and this arrangement is best seen in Figure 2 of the drawings. As shown by arrows 42 and dotted lines 44, the sleeve 20, roller 26 and wing rollers 32 are able to pivot through an angle of 20 about 200 in order to track the conveyor belt. The pivot angle will depend on various factors 0* °including the cross bar diameter and the length and internal diameter of the sleeve S.0 Tracking is activated by the edge regions of the conveyor,belt coming into contact with one or other of the wing rollers 32 as the conveyor belt moves off its centre line.

Turning to Figure 3 of the drawings the conveyor belt 24 is shown in its standard trough configuration. In sold lines the conveyor belt is shown in its central position but in dotted lines 46 the conveyor belt has been shown shifted to the right hand side of the assembly. As the belt shifts to one side as shown the edge 48 of the belt comes into contact with the wing roller 32a which will cause the wing roller 32a to commence rotating. The belt will also, however, place a drag on the wing roller 32a causing that wing roller to be urged to move forward, that is, in the direction of the travel of the belt. The effect of this will be to cause the sleeve 20, and hence the roller 26 to move to a skew position and thereby steer the belt back towards its central position.

The effective width of the belt is the distance between the edges 48 and 50, and at the elevation ICA98216()005.9 of the edges 48 and 50 the wing rollers are further apart than the effective width of the belt, when the belt is centralised.

The applicant has found that the central roller 26 is extremely effective in steering a trough shaped belt towards its central position. It is found that the wing roller 32 need not be used in any way for steering. The central roller, if in a skew or sloughed position, will steer the belt back towards the central position. An important aspect of the invention is that the belt will be steered back to position rather than pushed or forced into position as is the case with many prior art assemblies of this type.

It will be noted that the left hand edge 50 of the belt has, as the belt moves towards the right, moved away from the left hand wing roller 32b. Thus, the left hand wing roller 32b is completely out of contact with the edge of the belt and this will ensure that interference between the belt and the left hand wing roller 32b does not in any way hinder the pivoting of the assembly in the aforementioned manner. This is a dlifferent arrangement to at least many prior art assemblies where the wing or edge rollers needs to "cut into" the path of the belt when the assembly sloughs. With that type of arrangement the assembly tends to work against itself with part of the assembly trying to move to a sloughed position and another part of the assembly resisting that movement.

It will be noted that the wing rollers 32a and 32b are mounted in a generally vertical plane and o..

at an angle to the horizontal which is far steeper than the troughed sides of the conveyor belt. In "20 the arrangement shown in Figure 3 the conveyor belt has the sides thereof troughed at an angle go of approximately 450 The wing rollers 32a and 32b, however, are mounted at an angle cx of approximately 700. This will ensure that as the belt moves off-centre the edges of the belt will come into contact with one or other of the rollers 32a and 32b and the further the belt moves off-centre the greater will be the drag force on the respective roller and hence will be the greater 25 the force tending to pivot the assembly to a skewed position.

°o It is preferred that the angle of the troughed side of the belt and the angle of the wing roller is selected so that, at the point where there is contact between the edge of the belt and the wing roller, the included angle between these two components is relatively acute. With that arrangement the belt is able to slide or ride up the wing roller without cutting into the wing roller or damaging the edge of the belt.

CA98216&X5.9 6 As shown in Figure 1, the assembly is mounted so that the belt which travels thereon travels in the direction of arrow 52. The wing rollers 32a and 32b are, therefore, on the leading side of the central roller 26. This will ensure that the central roller 26 has a tendency to run true where the belt is travelling centrally.

The arrangement shown in Figures 4 and 5 of the drawings is similar to that shown in Figures 1 to 3 except that the central roller 54 is offset from the sleeve 56. The sleeve 56 is pivotable about pivot axis 58 relative to the cross bar 60 but, in other respects, the assembly is substantially the same as that shown if Figures 1 to 3. The assembly shown in Figures 4 and 5 is adapted to be mounted so that the belt which runs thereon runs in the direction of arrow 62 so that the roller 54 trails the sleeve 58 and the wing rollers 64 lead the sleeve 56.

It will be appreciated that there may be many variations to the above described embodiments without departing from the scope of the invention. The manner in which the wing rollers are mounted to the frame could, for example, be varied from that described herein. It is not essential that the wing rollers are adjustable relative to the frame but this is preferred in order to accommodate different belt configurations for the same assembly and also to allow for different sensitivity of set-up depending on user requirements.

S S.

oo S "7.