GB2108918A

GB2108918A - Apparatus having an articulated track for a moving endless loop

Info

Publication number: GB2108918A
Application number: GB08132714A
Authority: GB
Inventors: Philip Baxter
Original assignee: Ammeraal
Current assignee: Ammeraal
Priority date: 1981-10-30
Filing date: 1981-10-30
Publication date: 1983-05-25
Also published as: GB2108918B

Abstract

Apparatus having an articulated track for a moving endless loop, such as a conveyor belt or chain or a drive belt or chain, includes a linkage for permitting articulation of the track without substantially altering the tension in the loop. The linkage comprises a first link arm (25) pivotally connected at either end (30, 31) to first support means (15) for a first section of the track and to second support means (21) for a second section of the track respectively, and means such as a second link arm (26) pivotally connected at either end (32, 33) to said first and second support means (15, 21) respectively for maintaining the first and second sections of the track in alignment with guide means, such as rollers (17, 18) for changing the direction of the loop (11, 12) at the linkage. The locations of the pivotal connections (30, 31) of the first link arm (25) are selected to maintain the substantially constant loop tension during articulation of the linkage. <IMAGE>

Description

SPECIFICATION Apparatus having an articulated track for a moving endless loop This invention relates to apparatus having an articulated track for a moving endless loop. Such apparatus includes many applications of endless belts, chains or other bands of flexible material or connected links, for example conveyor belts or chains and drive belts or chains.

It is sometimes desirable to alter the alignment of part of the track for the loop in such apparatus.

For example, endless belt conveyors may be used for delivering material into bins. Where the same conveyor is used for delivering material to several different bins, which may be at different heights, it may be necessary to adjust the track of the conveyor so as to raise or lower the height of the end portion of the conveyor from which the material is discharged into the bins. The conveyor may then include a horizontal portion and an inclined portion, rollers being provided where the belt changes its direction from horizontal to inclined and vice versa. When the gradient of the inclined portion is changed, the length of belt which is taken up by being wrapped around part of the circumference of the rollers changes. It is not adequate to move the discharge end of the conveyor in a circular arc to alter the gradient, but it is also necessary to change the radius.On moving from horizontal to an inclined orientation, for example, it would be necessary to reduce the radius as part of the belt wraps round the guide rollers at the change of direction; if this is not done, the tension in the belt would rapidly become excessive as the inclination was increased.

Some belt conveyors are provided with flat beds below the upper run of the belt in order to support the belt. When the inclination of the conveyor is changed, it is then also necessary to ensure that the bed is kept tangential to the roller about which the belt moves, in order to make sure that the belt runs over the leading edge of the bed after the roller without scuffing and wearing the undersurface of the belt.

We have found that with a suitable linkage it is however possible for the inclination of the discharge end, or boom, of such a conveyor to move so as to maintain a substantially correct belt tension over a range of angular movement.

According to our invention we provide apparatus comprising an endless flexible loop driveable along a track having first and second sections which respectively comprise first and second support means for the track, wherein the second support means is connected to the first support means by an articulated linkage which allows the second section of the track to pivot relative to the first section and guide means are provided for changing the direction of the flexible loop at the linkage, and wherein the linkage comprises a link arm having a first pivotal connection to the first support means and a second pivotal connection, spaced apart from the first pivotal connection, to the second support means, and means for maintaining the first and second sections of the track in alignment with the guide means, the locations of the first and second pivotal connections being such as to maintain a substantially constant tension in the loop during articulation of the linkage.

The guide means may be constituted by rollers, pulleys, sprockets or simply curved blocks around which the loop can run smoothly. Similar means will of course be provided elsewhere on the track in order to guide the loop in the normal way.

There may be more than one articulated linkage of this kind in the apparatus. Since no adjustment of tension in the loop is required when the alignment of the track is changed, each such linkage can be altered independently without the need to reposition idler rollers or sprockets or other tensioners to take up the slack or to reduce overtension in the loop.

The means for maintaining the first and second sections of the track in alignment with the guide means is preferably a second link arm having one pivotal connection to the first support means and one pivotal connection, spaced therefrom, to the second support means. Such a link arm will control the alignment of the second section of the track relative to the first section of the track, and, in the case where the guide means is fixed relative to the first section of the track, it will consequently also control the alignment of the second section of the track relative to the guide means.

One embodiment of the invention is illustrated by way of example in the accompanying drawings, in which: Fig. 1 shows diagrammatically in side elevation the articulated linkage between a base portion of an endless belt conveyor and a boom portion when the boom portion is lowered to a horizontal position; and Fig. 2 is a similar view of the same apparatus when the boom portion is fully raised to an inclination of 450.

The conveyor shown in the drawings has an endless belt which travels forwards, that is to say from left to right in the drawings, on its upper run 1 and returns along a lower run 12. At each end, not shown in the drawings, the belt passes around a pulley drum.

The conveyor track is in two sections. The first section is fixed in a horizontal position. It contains the drive mechanism for the belt and is the section in which material is loaded onto the belt; it may be considered as the base portion of the conveyor.

The second section of the track is of adjustable inclination and is referred to herein as the boom portion.

The base portion of the conveyor is contained between side members 1 5 on either side of the upper and lower runs 11, 12 of the belt. Each side member 1 5 is formed as a shallow inward facing channel. Extending between the side members is a bed 1 6 for the upper run of the belt; the bed provides a flat surface over which the belt can slide.

Each side member also carries two guide rollers 17, 18. The upper guide roller 1 7 on each side member just touches the upper surface of the belt on its upper run 11, and the lower guide roller 18 just touches the upper surface of the belt on its lower return run 12. The two upper guide rollers 17 carried by the two side member 1 5 are relatively narrow and run along the two side edges of the belt, so as not to interfere with the passage of material along the conveyor. The width of the lower guide roller 18 is not important.The guide roller 1 8 is mounted on the side members 1 5 closer to the discharge end of the conveyor than are the guide rollers 17, such that the plane through the centres of the rollers as seen in the drawings makes an angle of 222 with the vertical.

Not shown in the drawings, the side members 1 5 also carry between them below the upper forward run 11 of the belt a suitable motor connected to a drive pulley drum around which the belt runs from the lower return run 12 to the upper forward run.

The boom portion of the conveyor comprises opposed side members 21 formed, like the side members 15, as shallow inward facing channels.

The separation between the side members 21 in the boom portion is somewhat greater than the separation between the side members 1 5 in the base portion, so that the side members 21 can overlap the side members 1 5 where the boom portion and the base portion are connected, the overlap taking in the location of the upper and lower guide rollers 1 7, 1 8.

The side members 21 of the boom portion also carry between them a bed 22 to provide a flat base over which the upper run 11 of the belt can slide and be supported without sagging. The nose end of the boom portion (not shown) carries an idler pulley drum around which the belt turns from the upper run to the lower run in order to discharge the material being carried and to return towards the base portion of the conveyor.

The base and boom portions of the conveyor are connected on each side by a pair of link arms 25, 26 which provide an articulated but controlled linkage between the two sections of the conveyor track.

The link arms are located in the spaces between the inner faces of the side members 21 of the boom portion and the outer faces of the side members 1 5 of the base portion of the conveyor.

The linkage on each side of the conveyor is the same. The link arm 25 is straight and is pivotally connected at one end 30 to the side member 1 5 of the base portion and at the other end 31 to the side member 21 of the boom portion. The link arm 26, which is cranked, is pivotally connected at one end 32 to the side member 1 5 and at the other end 33 to the side member 21.The precise locations of the pivot points 30, 31, 32 and 33, and the lengths of the link arms 25, 26 between their pivot points, are carefully selected to give the desired motion for the idler pulley drum at the nose end of the boom portion and thereby maintain a suitable tension in the conveyor belt, for different elevations of the boom section, while at the same time ensuring that the upper surface of the belt as it travels over the bed 22 is aligned with the lower rim of the upper guide roller 17, to which the upper run of the belt 11 is tangential.

The boom portion of the conveyor illustrated is designed to be elevated to a maximum of 450. At this elevation, as shown in Fig. 2, the angle in the cranked link arm 26 abuts the end 30 of the other link arm 25 and prevents further upward movement.

Either one of the link arms 25, 26, but not both, could be replaced by alternative means for maintaining the boom portion of the conveyor in alignment with the upper and lower guide rollers 17, 18. For example, if the bed 22 were to be extended as far as the upper guide roller 1 7, it would be possible to mount a planetary roller on this guide roller positioned below the extended bed 22 which would function to keep the bed and the belt against the guide roller, while at the same time allowing the belt to pass between the bed and the roller and allowing the bed to pass in and out of the gap between the guide roller and the planetary roller as the boom section rotates during adjustment of its elevation, in a movement controlled by the remaining link arm. The movements of the boom as the elevation is changed will be the same as its movements when controlled by the two link arms 25, 26. In either case the tension in the belt is automatically maintained at substantially its correct value as the elevation of the boom section of the conveyor is altered between the designed limits of horizontal and 450.

Claims

1. Apparatus comprising an endless flexible loop driveable along a track having first and second sections which respectively comprise first and second support means for the track, wherein the second support means is connected to the first support means by an articulated linkage which allows the second section of the track to pivot relative to the first section and guide means are provided for changing the direction of the flexible loop at the linkage, and wherein the linkage comprises a link arm having a first pivotal connection to the first support means and a second pivotal connection, spaced apart from the first pivotal connection, to the second support means, and means for maintaining the first and second sections of the track in alignment with the guide means, the locations of the first and second pivotal connections being such as to maintain a substantially constant tension in the loop during articulation of the linkage.

2. Apparatus as claimed in claim 1 wherein the means for maintaining the first and second sections of the track in alignment with the guide means comprises a second link arm having one pivotal connection to the first support means and one pivotal connection, spaced therefrom, to the second support means.

3. Apparatus as claimed in claim 1 or claim 2 wherein the guide means are fixed relative to one of the first and second sections of the track.

4. Apparatus as claimed in any one of the preceding claims wherein the first section of the track has a fixed inclination and the second section of the track is of adjustable inclination.

5. Apparatus as claimed in any one of the preceding claims wherein the endless flexible loop is a conveyor belt.

6. Apparatus as claimed in claim 5 wherein the belt is supported by a flat bed in each of the first and second sections of the track.

7. Apparatus as claimed in claim 4 and either one of claims 5 and 6 wherein the second section of the track comprises a boom for discharging material carried on the conveyor belt.

8. Apparatus as claimed in any one of the preceding claims wherein the guide means comprise rollers.

9. Articulated endless loop apparatus substantially as herein described with reference to and as illustrated in the accompanying drawings.