GB2059900A - Belt conveyor - Google Patents

Abstract

The conveyor comprises an endless belt (not shown), two spaced rollers (3, 4) over which the belt passes in operation, and an elongate trough (7). The trough (7) serves to support an upper stretch of the belt intermediate the rollers (3, 4) such that the opposite longitudinal edges of the belt are inclined upwardly and outwardly with respect to an intermediate central portion of the belt. This upper stretch is thereby prevented from sagging under the weight of the material carried by the belt. Furthermore the material tends to remain in the middle of the belt thereby decreasing spilling of material at the edges. <IMAGE>

Description

SPECIFICATION Belt conveyor This invention relates to belt conveyors of the type comprising an endless belt which passes over rollers at least one of which is driven to move the belt. The invention is concerned primarily, but not exclusively, with heavy duty belt conveyors for transporting large quantities of material, such as scrap metal or minerals, between processing stations.

It is known to support the belt of such a conveyor at intervals along its upper stretch by means of a series of horizontal rollers or a series of roller assemblies each comprising a horizontal roller arranged centrally with respect to the width of the belt and a respective roller inclined to the horizontal provided on either side of the horizontal roller. In the latter arrangement the edges of the belt are raised and the material carried by the belt is therefore less likely to roll off the sides of the belt.

In addition it is known to provide rubber skirts on either side of the belt which contact the upper surface of the belt as it runs beneath a hopper so as to prevent material fed from the hopper onto the belt from spilling over the sides of the belt. However the weight of the material on the belt causes the belt to sag between successive rollers or roller assemblies and this causes gaps to be created between the rubber skirts and the belt. Material may pass through these gaps and become trapped in the rollers leading to breakdown of the conveyor. Additionally, even when roller assemblies incorporating inclined rollers are provided, material may be blown off the belt by the wind where the conveyor is installed in the open air. This is a particular problem where the material to be conveyed incorporates a large quantity of dust, as is the case in a scap processing plant.

This invention provides a belt conveyor comprising an endless belt, two spaced rollers over which the belt passes and an elongate trough extending in the direction of the belt and serving to support an upper stretch of the belt intermediate the rollers such that the opposite longitudinal edges of the belt are inclined upwardly and outwardly with respect to an intermediate central portion of the belt.

In this manner the part of the belt above the trough is firmly supported and may be engaged by rubber skirts at its edges without there being any danger of large gaps being created between the belt and the skirts due to sagging of the belt. In addition the shape taken up by the belt above the trough will be such that the material carried by the conveyor will tend to remain in the middle of the belt thus decreasing spilling of material at the edges.

In a preferred embodiment the trough extends over substantially the complete distance between said two rollers, and is of constant cross-section substantially throughout its length. However the ends of the trough may be splayed outwards so as to minimise wear on the belt. Advantageously the cross-section of the trough includes a central flat portion and a respective inclined flat portion on either side of the central portion, the angle between each inclined portion and the central portion internally of the trough being an obtuse angle of, for example, about 1 35,. In operation of the conveyor the belt should be positioned centrally with respect to the width of the trough with the edges of the belt resting on the inclined portions.The inclined portions may be arranged to extend transversely beyond the belt when the belt is positioned centrally so as to allow for some transverse adjustment of the belt. Suitable results are achieved if the width of the central portion of the trough is about two thirds of the width of the belt and the width of the inclined portions is about one third of the width of the belt. For example, with a 36 inch width belt, the central portion may have a width of 24 inches and the inclined portions may have a width of 12 inches.

The trough may also include side walls which are preferably mutually parallel and perpendicular to the central portion. These walls serve to protect the material on the conveyor from the wind where the conveyor is installed outside. In the above described example these walls may have a height of about four inches. The tops of these walls may be provided with outwardly directed flanges having a width of about two inches for example, for the attachment of support members thereto.

The trough is preferably made of mild steel plate having a width of six millimetres and is shaped by rolling. The belt may be a rubber belt of a conventional type sold for this purpose. For example, it may be a double sided 4-ply rubber belt, each ply having a width of six millimetres. When such materials are used it is found that the belt passes easily over the trough without it being necessary to exert an excessive force on the belt and without causing excessive wear of the belt or trough, even where many tons of material are carried by the belt in an hour.

In a practical embodiment of the invention the belt passes around, and frictionally engages, two rollers one of which is arranged to be driven by an electric motor through gearing and the other of which is arranged to be adjustable to tension the belt. This adjustment is preferably such that said other roller can be moved towards and away from said one roller and also such that the axis of said other roller can be angularly displaced in a plane which incorporates the axes of both rollers to enable the rollers to be disposed precisely parallel and thus the belt to run parallel to the axis of the trough. The lower stretch of the belt may be supported intermediate said rollers by further rollers spaced at intervals.The conveyor may be arranged to be driven in the direction such that the upper stretch of the belt moves towards said one roller, and a chute may be provided to receive the material tipped off the belt as the belt passes around said one roller.

A scraper may be provided for removing any material which has become trapped on the upper surface of the lower stretch of the belt, for example by falling through gaps in the vicinity of said one roller. This device may comprise a rubber blade which engages the belt along a line which is inclined, for example at an angle of about 45t, with respect to the transverse direction of the belt, so that material which meets the blade is swept off one side of the belt by the motion of the belt.

In order that the invention may be more fully understood, a belt conveyor in accordance with the invention will now be described by way of example, with reference to the accompanying drawings, in which: Figure 1 is a perspective view of the conveyor with the belt removed; and Figure 2 is a section taken along the line A-A in Fig. 1 with the belt in place.

The belt conveyor shown in the drawings is typically intended for use in a scrap metal processing plant in which ferrous and nonferrous metals are separated from non-metallic materials. Such a conveyor may be used in a number of different applications in the plant and may be disposed horizontally or at an inclination.

Reference numerals 1 and 2 denote side members between which there extend a drive roller 3 driven by an electric motor (not shown) through gearing and an adjustable roller 4 capable of being moved towards and away from the roller 3. In operation of the conveyor the roller 3 is rotated in the direction of the arrow 5. An endless rubber belt 6 passes around, and frictionally engages, the rollers 3 and 4, the belt not being shown in Fig. 1 so as to render this figure easier to read. The upper stretch of the belt 6 is supported between the rollers 3 and 4 by a mild steel trough 7. The trough 7 comprises a central portion 8, inclined portions 9 and 10 on either side of the central portion, upstanding side walls 11 and 12, and flanges 1 3 and 14.

Such a conveyor is capable of transporting up to 80 tons per hour of scrap material containing pieces of metallic and non-metallic material of varying shapes having dimensions of about two to six inches as well as a high proportion of dust (that is finely divided nonmetallic material) in a trouble-free manner without unduly contaminating the surrounding area.

Claims (8)

1. A belt conveyor comprising an endless belt, two spaced rollers over which the belt passes, and an elongate trough extending in the direction of the belt and serving to support an upper stretch of the belt intermediate the rollers such that the opposite longitudinal edges of the belt are inclined upwardly and outwardly with respect to an intermediate central portion of the belt.

2. A belt conveyor according to claim 1, wherein the trough extends over substantially the complete distance between said two rollers.

3. A belt conveyor according to claim 1 or 2, wherein the ends of the trough are splayed outwards so as to minimise wear on the belt.

4. A belt conveyor according to claim 1, 2 or 3, wherein the cross-section of the trough includes a central flat portion and a respective inclined flat portion on either side of the central portion, the angle between each inclined portion and the central portion internally of the trough being an obtuse angle.

5. A belt conveyor according to claim 4, wherein the obtuse angle is about 135 .

6. A belt conveyor according to claim 4 or 5, wherein the trough includes side walls which are mutually parallel and perpendicular to the central portion of the trough.

7. A belt conveyor according to claim 6, wherein the tops of the side walls are provided with outwardly directed flanges for the attachment of support members thereto.

8. A belt conveyor substantially as hereinbefore described with reference to the accompanying drawings.