GB2069957A - Conveyor scraper - Google Patents

Abstract

In order to remove adhering material from a conveyor belt J, a plurality of blades A are coupled to a rotary shaft D positioned so that the blades A wipe the belt J as the shaft D rotates. The blades A are disposed within respective outer casings C pivoted on pivot shafts B between two blade mounting flanges on the shaft D. The arrangement is such that the blades A are forced centrifugally outwardly as the shaft D rotates against a spring force provided by cushioning springs. This enables the blades A to wipe the belt J over a relatively long distance and to move back to clear an obstruction on the belt J, thus providing a particularly efficient wiping action. <IMAGE>

Description

SPECIFICATION Conveyor scraper This invention relates to scrapers for belt-type conveyors.

In use of such conveyors to transport material between two spaced locations, the material to be transported is loaded on to the conveyor belt at a first location, by means of a hopper for example, and is discharged from the belt at a second location, being tipped into a bin, for example, as the belt passes around a roller at the end of its conveying run. However, some of the material may still adhere to the belt after it has passed the discharge location and in such cases a scraper is generally provided to remove this adhering material.

For example, the endless belt of the conveyor may have the scraper positioned immediately beneath the return run of the belt so as to wipe the lower surface of the belt in the return run (which corresponds to the upper surface of the belt in the conveying run). The scraper may be a flexible blade extending obliquely across the width of the belt so that material trapped behind the blade is caused to move to one side of the belt. However, such a scraper is in many cases found to be inadequate and rapidly becomes worn. It is an object of this invention to provide a conveyor scraper which will efficiently remove adhering material from the conveyor belt in a wide range of applications and which is capable of use over a long period.

According to the invention a conveyor scraper comprises a rotary shaft for positioning adjacent to the conveyor belt and transversely with respect to the direction of motion of the belt, and a plurality of blades coupled to the shaft and adapted to wipe the belt as the shaft rotates.

The blades may be capable of limited movement towards and away from the shaft, so that, as the shaft rotates, the blades are forced centrifugally outwardly with respect to the shaft whilst each being capable of displacement inwardly on contact with the belt. Accordingly each blade will contact the belt with a pressure which depends on the weight of the blade, the speed of rotation of the shaft and the degree of inward displacement of the blade. Furthermore each blade will wipe the belt over a relatively long distance, with the contact pressure generally increasing until the blade reaches its over-centre position after which the contact pressure decreases again. This provides a particularly efficient wiping action. Moreover the blades may move back to clear an obstruction on the belt.

Biasing means such as springs may be provided for controlling movement of the blades towards and away from the shaft. For example, such means may provide a spring force which must be overcome when the blades are forced centrifugally outwardly. Alternatively, or additionally, such means may provide a spring force which must be overcome when the blades are displaced inwardly.

By such means the contact pressure of the blades on the belt may be increased or decreased and the variation in contact pressure as the blades wipe the belt may be increased or decreased.

As well as, or instead of, being capable of such limited movement towards and away from the shaft, the blades may be capable of limited pivotal movement with respect to the shaft, so that, as the shaft rotates, the blades are caused by centrifugal action to take up positions in which they radiate outwardly from the shaft whilst each being capable of pivoting on contact with the belt.

This causes each blade to contact the belt with a pressure and at an angle which depend on the weight of the blade and the speed of rotation of the shaft. Furthermore each blade will be caused by such an arrangement to wipe the belt over a relatively long distance. This arrangement also enables the blades to pivot backwardly to clear an obstruction on the belt.

The means for limiting pivotal movement of the blades could be in the form of a cam surface on each blade which contacts an abutment surface when the blade pivots beyond a certain point.

Alternatively such means could be in the form of a hydraulic system in which fluid is caused to pass between two chambers by centrifugal action.

Such a system enables the degree of pivotal movement allowed to be controlled in dependence on the speed of rotation of the shaft. Moreover the pivotal movement of the blades may be controlled by biasing means in a similar manner to that described above with reference to control of the blade movement towards and away from the shaft. Similarly the means for limiting pivotal movement of the blades could be adapted to limit movement of the blades towards and away from the shaft.

It will be appreciated that, depending on the application to which the conveyor scraper is to be put, the blades may be arranged to be linearly and/or pivotally movable. For some applications the blades could be rigidly fixed with respect to the shaft. The number of blades provided may be varied so as to give the required belt coverage for adequate cleaning performance in a particular application. As well as being adapted to the material to be carried by the conveyor, the angle of contact, contact pressure and duration of contact of the blades should be adapted to the material of the belt, the tension of the belt (position of nearest rollers) and the speed of the belt. Clearly also the weight, size, shape and material of each blade will depend on the particular application to which the scraper is to be put.The material will be chosen so as to give a particular wear rate for a particular type of conveyor belt.

The scraper may be provided with means for heating the blades in applications where the adhering material, such as asphalt or rubber, is particularly difficult to remove from the belt.

The blades are preferably mounted in such a manner as to be capable of being replaced without removing the scraper from the conveyor.

Furthermore it is desirable for means to be provided for rotating the shaft in such a direction that, when a blade contacts the belt, the portion of the blade in contact with the belt is moving in the opposite direction to the belt. Such means may be in the form of a power take-off from the conveyor drive means.

The invention also provides a conveyor fitted with such a scraper.

Two embodiments of the invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a cross-section through the first embodiment, Figure 2 is a perspective view of the first embodiment, Figure 3 is a section through parts of the first embodiment, and Figure 4 is a cross-section through the second embodiment.

Referring to Figures 1 to 3, the conveyor scraper illustrated therein comprises four blades A disposed within respective outer casings C pivoted on pivot shafts B between two blade mounting flanges E on a rotary shaft D. The blades A are forced centrifugally outwardly as the shaft rotates against a spring force provided by cushioning springs F disposed within the casings C between portions of the blades A and locating dowels G attached to the casings C. The blades A are capable of moving inwardly when they contact a conveyor belt J in the vicinity of a return idler roller I mounted on a shaft H.

In the alternative embodiment illustrated in Figure 4, the blades A are retained within fixed recesses defined by a frame structure L on the rotary shaft D by means of retention plates K which are held in place by securing bolts M.

Clearance holes N are provided in the frame structure L for access to these bolts M. The blades A are again forced centrifugally outwardly against a spring force provided by cushioning springs F disposed between portions of the frame F and locating dowels G attached to the retention plates K, as the shaft D rotates.

Such a conveyor scraper could be used in the fields of mining (both surface and underground), sand, gravel and aggregate transport, and quarrying, as well as in processing and manufacturing industries (including the food industry).

Claims (11)

1. A conveyor scraper comprises a rotary shaft for positioning adjacent to the conveyor belt and transversely with respect to the direction of motion of the belt, and a plurality of blades coupled to the shaft and adapted to wipe the belt as the shaft rotates.

2. A scraper according to claim 1, wherein the blades are capable of limited movement towards and away from the shaft, so that, as the shaft rotates, the blades are forced centrifugally outwardly with respect to the shaft whilst each being capable of displacement inwardly on contact with the belt.

3. A scraper according to claim 2, wherein biasing means are provided for controlling movement of the blades towards and away from the shaft.

4. A scraper according to claim 3, wherein the biasing means provide a spring force which must be overcome when the blades are forced centrifugally outwardly.

5. A scraper according to claim 3 or 4, wherein the biasing means provide a spring force which must be overcome when the blades are displaced inwardly.

6. A scraper according to any preceding claim, wherein the blades are capable of limited pivotal movement with respect to the shaft, so that, as the shaft rotates, the blades are caused by centrifugal action to take up positions in which they radiate outwardly from the shaft whilst each being capable of pivoting on contact with the belt.

7. A scraper according to any preceding claim, wherein means are provided for heating the blades.

8. A scraper according to any preceding claim, wherein the blades are mounted in such a manner as to be capable of being replaced without removing the scraper from the conveyor.

9. A scraper according to any preceding claim, wherein means are provided for rotating the shaft in such a direction that, when a blade contacts the belt, the portion of the blade in contact with the belt is moving in the opposite direction to the belt.

10. A conveyor scraper substantially as hereinbefore described with reference to Figures 1 to 3 or Figure 4 of the accompanying drawings.

11. A conveyor fitted with a scraper according to any preceding claim.