WO2003068639A1

WO2003068639A1 - Conveyor belt training idler roller assembly and installations inclduing same

Info

Publication number: WO2003068639A1
Application number: PCT/IB2003/000444
Authority: WO
Inventors: Douglas John Cumberlege
Original assignee: Douglas John Cumberlege
Priority date: 2002-02-11
Filing date: 2003-02-11
Publication date: 2003-08-21
Also published as: WO2003068638A1; AU2003245717A1; AU2003205967A1

Abstract

A training idler roller assembly (4) is provided comprising an operatively generally horizontal freely rotatable idler roller (6) having an outer surface for contacting and supporting a generally flat conveyor belt (2) in use. The idler roller is of a type that is rotatably supported by a support assembly (7, 8, 11) that enables the roller to slew about an axis (5) that is operatively transverse to a conveyor belt supported by the idler roller. A drag affording element (15) typically in the form of a skid disc is associated with each end of the idler roller so as to be in continuous contact with the conveyor belt at least when it follows a desired path. Lateral drift of the conveyor belt supported by the assembly, in use, is corrected by a slewing force on the assembly imparted by uneven drag on the two drag affording elements. As lateral drift occurs the drag on one element increases whilst the drag on the other element decreases thereby enhancing the corrective action applied to the idler roller assembly.

Description

CONVEYOR BELT TRAINING IDLER ROLLER ASSEMBLY AND INSTALLATIONS INCLUDING SAME

FIELD OF THE INVENTION

This invention relates to a conveyor belt training idler roller assembly of the type that is adapted to slew about a pivot axis generally transverse to the plane of the conveyor belt in order to steer the belt back towards a central position on the idler roller when the belt tends to drift laterally to one or other side of the intended conveyor path. The invention also relates to conveyor belt installations including such a training idler roller.

Still more particularly, but not exclusively, the invention is concerned with a conveyor belt training idler roller that can be used effectively in conveyor belt installations in which the belt moves rather slowly such as are typical in the food industry.

BACKGROUND TO THE INVENTION

It is well known in the art that conveyor belts in general require some form of steering facility for returning a conveyor belt to a central position on its support rollers whenever it tends to drift laterally to one or other side of the desired path of movement during operation. Various solutions have been proposed and implemented.

Some of these employ arrangements that engage the edges of the conveyor belt in order to urge the conveyor belt inwards to a central position whenever it drifts away from such a central position. These are considered by applicant to be particularly inappropriate as applied to conveyor belts in the food industry as the belts are typically extremely thin and consequently flexible and would, in applicants view, not react to such lateral thrust to push them back into the required path of movement. Even if such an arrangement were effective, it would tend to fold the belt at the edges when exerting a thrust on it thereby resulting in the edges of the conveyor belt become frayed or damaged relatively rapidly. Because the damaged areas can allow bacteria to set in, the conveyor belt would then have to be replaced.

Other devices generally tend to fall into one of two categories. The first is that of complex devices in which the position of the edge of a conveyor belt is continuously monitored, optically for example using optical fibres or infrared radiation, or electronically. In this case sophisticated pneumatic, hydraulic, or electrical steering mechanisms are activated to impart movement to a training roller to counteract the lateral drift of the conveyor belt. These complicated devices are, in the first place, generally costly and, secondly, often require significant maintenance in view of their complexity.

The other general category of training rollers is that of freely rotatable training idler rollers wherein the lateral movement of the belt itself is arranged to achieve the steering effect and it is to this category that the present invention belongs.

One general arrangement in this category that appears to be the first in a line of related constructions is described in United States patent No 2,330,923 to Samuel D Robins. In this case a training idler roller is pivotally mounted centrally of the length of the roller (in other words centrally across the width of the conveyor) and internally on a support shaft so as to be capable of slewing within limits around an axis transverse, and in particular, at right angles to, the conveyor belt that is being supported. The outer surface of the roller is crowned so that its outer diameter decreases from the centre of the roller towards each end and drag created by engagement of the belt with the roller surface tends to slew the idler roller about the pivot axis when the belt drifts laterally towards one or other end of the roller. This results from the increased drag on that side of the pivot. Subsequent United States patent number 5,911 ,304 describes this type of arrangement with a somewhat improved bearing construction and wherein the crowned effect is achieved by tapering the two ends of the outer surface of the roller thereby simplifying its manufacture.

United States patents 2,570,364 and 6,173,830 describe these general principles as applied to troughed conveyors and wherein friction rollers or friction pads are provided for the conveyor belt edge to move into contact with when the belt moves towards one or other side of its desired path in order to steer it back to such desired path. Contact between the belt and friction roller or pad clearly only occurs in each of these cases when a steering action is necessary from time to time as abrasive wear on both the friction roller or pad and the belt would be unduly high if there were any form of constant contact between the belt and friction roller or pad bearing in mind that such conveyor belts are typically used in the mining and ore processing industries in which highly abrasive particles are present in abundance.

This simple expedient operates effectively in many different applications in which belt speeds are relatively high and the conveyor belts themselves are of a robust, generally heavy duty, construction typical of the mining and ore processing industries.

However, applicant's attempts to apply the general principles set out in the patents referred to above have not met with adequate success in the case of the slow-moving, relatively thin, generally flat and insubstantial conveyor belts typical of such industries as the food industry.

These slow-moving conveyor belts, may, for example, move at speeds of from 1 mm to 500 mm (about 0.04 to about 20 inches) per second, and are often composed of mono film belting, extruded plastic sheet or even textile or webbing materials that may be as thin as 1 mm (about 0.04 inches) or even less in some instances, have not been successfully tracked, as far as applicant is aware, utilizing training idler rollers of this general type.

OBJECT OF THE INVENTION

It is an object of this invention to provide a training idler roller of the latter general type that exhibits a satisfactory steering effect and, more particularly, enhanced sensitivity to the lateral drift of a conveyor belt supported thereon, particularly, but not exclusively, slow-moving, flat conveyor belts. It is another object of the invention to provide an installation including such a training idler roller.

SUMMARY OF THE INVENTION

In accordance with one aspect of this invention there is provided a training idler roller assembly comprising an operatively generally horizontal freely rotatable idler roller having an outer surface for contacting and supporting a generally flat conveyor belt in use, the idler roller being rotatably supported by a support assembly that enables the roller to slew about an axis that is operatively transverse to a conveyor belt supported by the idler roller, and a drag affording element associated with each end of the idler roller such that lateral drift of a conveyor belt supported by the assembly, in use, imposes a slewing force on the assembly to tend to correct such lateral drift and return the conveyor belt to a central desired path, the idler roller assembly being characterized in that at least a part of the operative surface of the drag affording elements is, in each case, in line with an operative part of the outer surface of the idler roller and positioned immediately adjacent an end of the idler roller; in that the length of the idler roller is less than the width of a conveyor belt to be supported thereby; and in that the drag affording elements are dimensioned and arranged such that each edge of a conveyor belt operatively supported by the idler roller assembly is in continuous contact with its associated drag affording element, at least when the conveyor belt follows a desired path.

Further features of the invention provide for the drag affording element, in each case, to be either a non-rotatable element, conveniently a disc, providing a skid surface adjacent and in line with the operative support surface of the roller so that a conveyor belt supported by the assembly will remain substantially flat, in particular towards its edges, or, alternatively, for the drag affording element to be a rotatable element that has an optionally adjustable braking mechanism inhibiting its freedom to rotate so as to provide controlled drag that is imposed on the assembly to slew the roller about said axis; and for the diameter of the outer surface of the idler roller to be constant along the entire length of the roller (other than in the region of any central low friction band when said band is defined by a groove as is discussed hereinafter) or, alternatively, for the end regions of the outer surface of the idler roller to be tapered, preferably with an angle of taper of about one to about three degrees, so as to enhance the steering effect of the present invention with the well-known expedient of the prior art.

Still further, the idler roller may, as indicated above, have a central band of relatively low friction as set out more fully in my copending patent application of even date and filed under an identical title and claiming convention priority from the same basic application as this application, namely, so that in provisional patent application number 2002/1133 filed on 11 February 2002 and an identical title to the present application. The content of my said copending patent application is incorporated herein by reference. Such a low friction band may be a recessed band so that there is no contact between the belt and band in that area in use thereby creating a zero friction situation, or alternatively, the surface of the band is defined by a material different from the material defining the balance of the outer surface of the roller, typically a low friction material such as polytetrafluoroethylene (PTFE), high-density polyethylene, a silicon based low friction material or other low friction material.

Typically, the support assembly may comprise a pivot arrangement positioned generally centrally of the length of a tubular roller and internally thereof such that the pivot axis may be operatively transverse to a conveyor belt in contact with the outer surface of the roller.

In accordance with a second aspect of the invention there is provided a conveyor belt installation comprising a series of support rollers supporting a conveyor belt in conventional endless manner with at least one training idler roller assembly as defined above operatively supporting a zone of the conveyor belt, the installation being characterised in that the conveyor belt is generally flat in the transverse direction; the width of the belt is greater than the length of the idler roller; and the drag affording elements are such that, at least when the conveyor belt follows its desired path, both edges of the belt contact their associated drag affording element on a continuous basis.

A further feature of this aspect of the invention provides for the training idler roller to be installed in the return pass of the conveyor belt between two non- training idler rollers with the angle of contact (wrap) between the conveyor belt and training idler roller being from 15 to 180 degrees, preferably from about 40 to about 150 degrees.

It will be understood that because the conveyor belt is in constant contact with the drag affording element at both sides of the conveyor belt, when the conveyor belts drifts laterally, not only is an increased drag exerted on the training idler roller assembly at the side of the belt towards which the conveyor belt moves laterally, but a corresponding decrease in the drag exerted at the other side of the belt occurs simultaneously. There is thus a steering force exerted on the training idler assembly from both sides as opposed to the prior art situation in which the steering force is exerted only at one side of the training idler roller. It is believed that this, at least in part, results in the extremely fast reaction that has been noted when implementing the invention, at least at an experimental level.

It will be noted that, because of the generally clean environment in which food grade belts and the like are utilized, the available selection of suitable abrasion resisting materials, and the availability of acceptable lubricants that can optionally be used, the matter of undue wear on the belt can be adequately addressed.

In order that the above and other features of the invention may be more fully understood different embodiments of the invention will now be described with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:-

Figure 1 is a schematic plan view illustrating the general mode of operation of a training idler roller according to the invention;

Figure 2 is a schematic side elevation of a portion of the length of one form of conveyor belt installation including a training idler roller according to the invention and illustrating the angle of wrap;

Figure 3 is a sectional elevation of one embodiment of idler roller assembly according to the invention;

Figure 4 is an end view of one variation of idler roller assembly of the type illustrated in Figure 3; Figure 5 is an end view of an alternative variation of idler roller assembly of the type illustrated in Figure 3; and,

Figure 6 is a sectional elevation similar to Figure 3 but showing a number of variations that may be made within the scope of the invention.

DETAILED DESCRIPTION WITH REFERENCE TO THE DRAWINGS

Referring firstly to Figures 1 and 2, the training idler roller assembly according to the invention, generally indicated by numeral (1), is most effectively, but not necessarily, introduced into a conveyor belt installation in the return pass (2) of a conveyor belt (3).

In this embodiment of the invention the idler roller is installed between two freely rotatable conventional idler rollers (4) supporting the return pass of the conveyor belt below the level of the two coplanar horizontal rollers (4) so that an increased angle of wrap around the training idler roller is achieved. The exact angle of wrap required will vary from one application to the next and according to the nature of the belt and the nature of the surface of the rollers themselves and will generally have to be established empirically at the present state of development of the invention for each particular application. The angle of wrap is indicated by the letter "A" in Figure 2. Clearly, this angle can be easily changed simply by adjusting the spacing between the two conventional rollers (4) or adjusting the vertical position of the training idler roller (1).

The training idler roller assembly is mounted so that it is freely rotatable, within restricted limits, about a generally vertical axis that is indicated by numeral (5) so that it can rotate about this axis when subjected to unequal forces (drag) on each side of the centre of the conveyor in order to direct the conveyor belt back to a central position. The exact direction in which the axis (5) extends relative to the conveyor belt will usually be at right angles to the belt, but certain steering effect can be achieved by inclining the axis somewhat forwards or rearwards relative to the direction of travel of the belt. The general functioning of such a training idler roller is set out in the earlier patents referred to above as well as earlier US patent No 1 ,833,180 and the disclosure of those patents is incorporated herein by reference.

Referring now particularly to Figure 3, the training idler roller assembly (4) comprises a tubular idler roller (6) freely rotatable about its own axis. The idler roller is mounted by means of a pair of laterally spaced bearings (7) carried on an inner sleeve (8) through which a support shaft (9) passes with appreciable clearance that is indicated by numeral (10). The inner sleeve is carried by a pivot and journal arrangement indicated by numeral (11) so that the roller and sleeve can slew about the axis (5) in order to achieve the steering effect referred to above. As indicated above, the axis of the pivot will be generally transverse and, in particular, generally at right angles to the belt where it passes over the roller. It should be pointed out that this axis could be at an incline to the belt but in that case the belt itself is restricted to movement in only one direction, that is, the direction towards which the pivot is inclined.

In this embodiment of the invention the outer surface of the roller is defined by that of an elastomeric layer (12) bonded onto a tubular base and the surface of which is of constant outer diameter for the entire length of the roller. As an optional aid to the steering effect provided by this invention the idler roller may have a central band of relatively low coefficient of friction, either in the form of a groove (13) that simply remains out of contact with the belt and therefore exhibits no friction with the belt (9) (as shown in the lower half of Figure 3), or it may assume the form of a somewhat broader band (14) of material that exhibits a lower coefficient of friction than the outer regions (as shown in the upper half of Figure 3). This construction is more fully set forth in my copending patent application of even date. As provided by this invention, there is provided at each end of the idler roller, a drag affording element, in this case in the form of a skid disc (15). The outer diameter of the skid discs is substantially the same as the outer diameter of the idler roller itself and the outer surface (16) of the skid disc forms substantially a continuation of the outer surface of the idler roller. However the skid discs are mounted non-rotatably on the inner sleeve (8) so that, when the conveyor belt moves in contact with the idler roller, the latter rotates whilst the skid discs remain stationary. Also, as provided by the invention, the length of the idler roller is somewhat less than the width of the conveyor belt so that the edges (17) of the conveyor belt ride continuously on the periphery of the skid discs.

The extent to which the edge of the belt overlaps the skid discs is preferably about 50% of the width of the disc so that whenever the belt drifts laterally with respect to the idler roller assembly it will contact the greater portion of the width of one disc and a lesser portion of the width of the other disc thereby increasing the drag on one side and decreasing the drag on the other side. This then provides a substantially equal and opposite turning force to the two sides of the training idler assembly that tends to react more rapidly to cause the conveyor belt to return to the central position when the drag on the two skid discs is substantially equal.

It will be noted in Figure 4 that the skid disc may be a complete disc thereby extending around the entire periphery of the end of the roller or, alternatively, as illustrated in Figure 5, and indicated by numeral (15a), it may extend only around a part of the end of the roller. Still further, the skid disc could be rotatable itself provided that there is adequate resistance to rotation so as to create a drag by cooperation with the belt to impart a steering force to the idler roller assembly. Any suitable mechanism could be used for this purpose and the mechanism could be adjustable such as that described in prior US patent 2,570, 364 to which reference is made above and the disclosure of which is incorporated herein by reference for this purpose. Numerous other modifications may be made to the embodiment of the invention described above without departing from the scope hereof. Simply by way of example, Figure 6 illustrates a few possible variations. Thus, for example, the outer surface of the idler roller itself could be provided with slightly tapering surfaces towards each end thereof in order to further enhance the steering effect that the conveyor has on the idler roller assembly. Typically such tapered regions that are indicated by numeral (18) could extend for approximately one-third of the length of the roller and the central region (19) could be of right circular cylindrical shape.

Also, the skid discs (20) are shown in this case is being mounted directly onto the shaft (21) instead of the inner sleeve (22) which, in this case, is rather short and not spaced from the inner surface of the roller itself. Also, any sort of bearing assembly could be used and there is illustrated in Figure 6 a self aligning bearing (23) with auxiliary lateral supports (24).

Numerous other variations may be made without departing from the scope hereof.

Claims

CLAIMS:

1. A training idler roller assembly (4) comprising an operatively generally horizontal freely rotatable idler roller (6) having an outer surface for contacting and supporting a generally flat conveyor belt (2) in use, the idler roller being rotatably supported by a support assembly (7, 8, 11) that enables the roller to slew about an axis (5) that is operatively transverse to a conveyor belt supported by the idler roller, and a drag affording element (15, 15a) associated with each end of the idler roller such that lateral drift of a conveyor belt supported by the assembly, in use, imposes a slewing force on the assembly to tend to correct such lateral drift and return the conveyor belt to a central desired path, the idler roller assembly being characterized in that at least a part of the operative surface (16) of the drag affording elements is, in each case, in line with an operative part of the outer surface of the idler roller and positioned immediately adjacent an end of the idler roller; in that the length of the idler roller is less than the width of a conveyor belt to be supported thereby; and in that the drag affording elements are dimensioned and arranged such that each edge (17) of a conveyor belt operatively supported by the idler roller assembly is in continuous contact with its associated friction affording element, at least when the conveyor belt follows a desired path.

2. A training idler roller assembly as claimed in claim 1 in which the drag affording element, in each case, is a non-rotatable element providing a skid surface adjacent and in line with the operative support surface of the roller so that a conveyor belt supported by the assembly will remain substantially flat, in particular towards its edges.

3. A training idler roller assembly as claimed in claim 1 in which the drag affording element is a rotatable element that has an optionally adjustable braking mechanism inhibiting its freedom to rotate so as to provide controlled drag that is imposed on the assembly to slew the roller about said axis.

4. A training idler roller assembly as claimed in any one of the preceding claims in which the diameter of the outer surface of the idler roller is constant along the entire length of the roller (other than in the region of any central low friction band when said band is defined by a groove).

5. A training idler roller assembly as claimed in any one of claims 1 to 3 in which the end regions of the outer surface of the idler roller are tapered

(18).

6. A training idler roller assembly as claimed in any one of the preceding claims in which the idler roller has a central band of relatively low friction selected from a recessed band (13) so that there is no contact between the belt and band in that area in use thereby creating a zero friction situation and a band (14) of a material different from the material defining the balance of the outer surface of the roller.

7. A training idler roller assembly as claimed in any one of the preceding claims in which the support assembly comprises a pivot arrangement (11) positioned generally centrally of the length of the idler roller and internally thereof such that the pivot axis may be operatively transverse to a conveyor belt in contact with the outer surface of the roller.

8. A conveyor belt installation comprising a series of support rollers (4) supporting a conveyor belt (2) in endless manner with at least one training idler roller (1) assembly as claimed in any one of claims 1 to 7 operatively supporting a zone of the conveyor belt, the installation being characterized in that the conveyor belt is generally flat in the transverse direction; the width of the belt is greater than the length of the idler roller; and the drag affording elements (8) are such that, at least when the conveyor belt follows its desired path, both edges (17) of the belt contact their associated drag affording element on a continuous basis.

9. A conveyor belt installation as claimed in claim 8 in which the training idler roller is installed in the return pass of the conveyor belt between two non-training idler rollers with the angle of contact (wrap) ("A") between the conveyor belt and training idler roller being from 15 to 180 degrees.

10. A conveyor belt installation as claimed in claim 9 in which the angle of contact is from about 40 to about 150 degrees.