GB2054504A - Conveyor belt scraper - Google Patents

Abstract

A scraper for wiping clean a surface, e.g. the undersurface, of a conveyor belt (40) comprises an elongate blade (11), mountable across the belt and resiliently biased into scraping contact with the belt surface so as to ride up and down as the belt flexes and the blades wears during use. The blade is supported, in use, between two rigidly mounted spaced apart posts (12, 13) on which mounting means (16, 17) at opposite ends of the blade are slidingly fitted. Compression springs (23, 24) act on opposite end regions of the blade to give the biasing force. The springs and mounting means are adjustable as an assembly on the posts in order to compensate for blade wear and maintain the biasing force in an adequate range. <IMAGE>

Description

SPECIFICATION Conveyor belt scraper The invention relates to conveyor belt scrapers.

Scrapers are specialised items of equipment which are used to wipe clean a surface of a conveyor belt, usually on the bottom run of the conveyor belt.

Although this might appear to be a straight-forward operation, the efficient cleaning of conveyor belts is a major and costly problem in many industries.

Various types of belt cleaning equipment have been used over the years, mostly with limited success and many requiring constant attention and maintenance.

There is in general a need for an efficient reliable scraper which is easy to handle and to install but which does its job properly.

Scrapers are known which comprise an elongate blade, mountable across the belt and resiliently biased into scraping contact with the belt surface so as to ride up and down as the belt flexes and the blade wears during use. Biasing may for example, be effected by two compression springs, one acting on each opposite end region of the blade. Such an arrangement gives a symmetrical wearing action across the belt-engaging surface of the blade, in use, and reduces the risk of uneven wear on the belt itself.

In use, the belt-engaging surface of the blade will gradually wear. As wear occurs, the blade will automatically be advanced by the compression spring means to maintain it in contact with the belt.

This in turn will cause the biasing force to decrease as the spring means extend, and leads to an overall loss of cleaning efficiency.

According to the present invention a scraper for wiping clean a conveyor belt surface comprises an elongate blade designed to be mounted across the belt surface and biased into contact with that surface and first and second mounting means connected to opposite ends of the blade, each mounting means having an associated mount comprising a support designed for rigid mounting relative to the belt and relative to which the respective mounting means is slidable, a backing member, resilient biasing means acting between the backing member and the mounting means and adjustment means for locating the assembly of backing member, biasing means and mounting means at any selected one of a number of positions on the support.

Once a scraper according to the invention has reached a certain degree of wear it is a simple matter to adjust the assemblies at each side of the blade on the respective supports in order bodily to shift the blade closer to the belt surface, and to fix the assemblies in their new positions. The worn section of the blades is thus compensated for and the biasing means are compressed to apply acceptable forces to the blade. Reduction of the biasing force to inefficient loads can thus be avoided.

Conveniently each support is a post on which the respective mounting means is slidable and each biasing means is a helically coiled compression spring coiled about the respective post and lying between the associated backing member and mounting means. This provides a particularly simple and compact arrangement, which is also sturdy and easily serviced.

Preferably each backing member is a collar carried on the respective post and each adjustment means comprises a cooperating mechanism between the collar and the post by means of which the collar, when rotated, advances axially along the post.

The cooperating mechanism may comprise a screw threaded engagement between the collar and the post. Alternatively a projection inside the collar may engage a helical groove in the post, or a groove in the collar may be engaged by a projection from the post.

Whatever mechanism is employed to advance the blade as it wears, the adjusting means will normally incorporate provision to retain the blade in any one of a plurality of progressively more advanced positions.

A specific conveyor belt scraper embodying the invention is shown in the accompanying drawing. It is only one example of forms which the invention might take.

In the drawings: Figure 1 shows the scraper in "exploded" perspective; and Figure 2, drawn to an enlarged scale, shows parts of the scraper of Figure 1.

The scraper consists essentially of an elongate blade 11 which is supported between two rigid posts 12,13. The blade 11 is rectangular and can be made of either flexible or hard polyurethane elastomer, or of various other types of plastics and rubbers, depending upon the particular application and the type of material being conveyed. The blade is bonded to a steel plate 15; or it could be bolted between two steel plates, plate 15 and a similar plate on the opposite face of the blade. The plate 15 extends beyond each end of the blade and is provided at its ends with mounting means in the form of respective tubular bushes 16, 17 welded to the plate.

Each bush 16, 17 slides on a respective one of the two posts between which the blade, in use, is supported. Each post 12, 13 is a circular cylindrical hardened steel rod which rises from an associated base plate 18, 19. The tod is welded to the base plate.

Spaced pairs of holes 20 are drilled in each base plate. Similarly-spaced elongate slots 21 are machined into the beds of two angle brackets 18A, 19A. A respective one of these brackets is bolted to each base plate, so that the spacing between the two posts 12, 13 can be accurately adjusted (via the slots) when the brackets are rigidly secured to the main mounting - usually part of the conveyor frame - on which the whole scraper unit is carried. The mounting is indicated generally at 22.

High tensile compression springs 23, 24 are helically coiled about each post 12, 13. They are sandwiched between backing members in the form of respective adjustable collars 29, 31 and the blade end bushes 16, 17. When the scraper unit is assembled, the collars are fitted onto the posts, the springs are slid over the posts, the blade end bushes are then slid over the posts and on top of the springs, and the bushes are then pressed down to compress the springs. With the springs compressed, one of two thick circular steel washers 25, 26 is slid over the top of each post 12, 13. A respective one of the two cotter pins 27, 28 is then inserted into one of a longitudinal succession 32, 33 of holes.When the scraper is initially assembled, the springs 23, 24 are compressed and the cotter pins 27, 28 are inserted in the lowest of each of these sets of holes 32, 33 (i.e.

the hole nearest each respective base plate 18, 19).

Each of the two collars 29, 31 is helically grooved.

A pin respectively 34, 34A projects from the bottom end of each post 12, 13 and engages in the groove of the adjacent collar 29 or 31. The base of the collar is hexagonal, so that it can be rotated with a suitably sized spanner. As the collar is rotated, the cooperating inter-engagement between the projecting pin 34, 34A and the groove in the collar causes the collar to advance along the post.

A second series of holes respectively 35, 36 is spaced longitudinally along each post 12, 13. The spacings between each hole in this second series are identical to the spacings between each hole in the first series of holes 32, 33 but the second series occupies the lower portion of the post (i.e. towards the base plate 18 or 19) whereas the first series extends along the upper portion of the post.

In use, the scraper is initially assembled and mounted as illustrated in the drawing, with the cotter pins 27, 28 in the lowest of the holes 32, 33 and with the base of each collar 29, 31 hard against the base plate 18, 19 from which the associated post rises.

The top edge of the blade 11 bears against the lower surface of the bottom run 40 of the conveyor belt. The blade 11 can be slightly narrower in width than the conveyor belt, because the material being conveyed does not usually extend across the full width of the belt. The unit is positioned in such a way that, when the blade is in full engagement with the belt, the springs 23, 24 are in a state of resilient compression, and the blade end bushes 16, 17 are thus pushed axially away from the cotter pins 27, 28 and towards the base plates 18, 19.

As the blade wears, it still remains compressively biased against the belt until the blade end bushes 16, 17 have moved completely back up against the cotter pins 27, 28. When this state of affairs is reached, each top cotter pin 27, 28 is removed and is reinserted into the next hole along in the series of holes 32, 33; each collar 29, 31 is rotated to advance it axially along its post 12, 13 until the first hole of each second series of holes 35, 36 is uncovered; and bottom cotter pins are then inserted into those holes to maintain the collars in those positions. The procedure is repeated until all the available adjustment has been taken up.

It will be appreciated that this enables wear to be compensated for, without diminishing the biasing force exerted by the compression springs 23, 24.

When all available adjustments have been made and the blade is completely worn, it can be inverted and its bottom surface then presents a completely new scraping edge to the belt. In remounting the inverted blade, the bottom cotter pins are removed, the collars 29, 31 moved to rest on the base plates and the top cotter pins 27, 28 placed in the lowermost of the top sets of holes. The full range of adjustment is again available as the second edge of the blade wears.

It will be appreciated that the overall design of the scraper is so simple and sturdy that there is very little chance of the mechanism being jammed by the scrapings from the belt. Scrapings will fall freely from the belt, since the scraper contains no sharp angles or projecting mechanisms on which the material can build up and into which it might penetrate and seize.

It will be understood that various modifications can be made to the scraper as described. The collar system of adjustment and the use of cotter pins as stops can each be changed. Adjustment of parts relative to the post is not essential, and adjustment may be effected by adjustment of a slide carrying the post or other support relative to a slide plate that is secured to the conveyor frame. It is not essential that coiled compression springs be used, and the biasing means could be constituted by a compressive medium such as relatively hard but resilient rubber blocks.

Claims (13)

1. Ascraperforwiping clean a conveyor belt surface, the scraper comprising an elongate blade designed to be mounted across the belt surface and biased into contact with that surface and first and second mounting means connected to opposite ends of the blade, each mounting means having an associated mount comprising a support designed for rigid mounting relative to the belt and relative to which the respective mounting means is slidable, a backing member, resilient biasing means acting between the backing member and the mounting means and adjustment means for locating the assembly of backing member, biasing means and mounting means at any selected one of a number of positions on the support.

2. A scraper according to claim 1 in which each support is a post on which the respective mounting means is slidable.

3. A scraper according to claim 2 in which each biasing means is a helically coiled compression spring coiled about the respective post and lying between the associated backing member and mounting means.

4. A scraper according to claim 2 or claim 3 in which each mount includes stop means secured to the post on the opposite side of the mounting means to the biasing means.

5. A scraper according to claim 4 in which the position of the stop means on the post is adjustable.

6. A scraper according to any one of claims 2 to 5 in which each backing member is a collar carried on the respective post, and each adjustment means comprises a cooperating mechanism between the collar and the post by means of which the collar, when rotated, advances axially along the post.

7. A scraper according to claim 6 in which the cooperating mechanism comprises a screw threaded engagement between the collar and the post.

8. A scraper according to claim 6 in which the cooperating mechanism comprises a pin engaging a helical groove, one formed on the post and the other on the collar.

9. A scraper according to claim 8 and including second stop means secured to the post on the opposite of the collar to the biasing means.

10. A scraper according to claim 9 in which the position of the second stop means on the post is adjustable.

11. A scraper according to ciaims 5 and 10 in which each of the stop means and the second stop means is a cotter pin engageable in any selected one of two respective series of transverse holes formed in the post.

12. A scraper according to claim 11 in which the spacing between adjacent holes in each series is substantially identical.

13. A scraper substantially as herein described with reference to the accompanying drawings.