GB2242878A - Roller mounting in tubular belt conveyors - Google Patents

Abstract

A conveyor comprises a conveyor belt 10 and a plurality of roller assemblies 11 spaced apart in the direction of travel of the belt for containing the conveyor belt in tubular form over part of its length. Each roller assembly comprises a mounting frame 12 and a plurality of rollers 13 each supported at one end only by the mounting frame. Each roller comprises a shell mounted on a spindle via bearings, the spindle protruding from one end only of the shell. <IMAGE>

Description

CONVEYORS This invention relates to conveyors, and more particularly to conveyors of a type which will be referred to as tubular conveyors.

Tubular conveyors are known. They are conveyors of a type in which material is loaded onto a flat conveyor belt, which is then progressively rolled into a tubular form with opposite edges overlapping so that the material is transported in what is effectively a moving tube. The conventional method for containing this tube is to pass it through a series of frames each supporting a plurality of rollers which contact the outer surface of the conveyor belt. Typically, these rollers consist of a fixed spindle, which is supported at both ends, and a roller shell which is mounted for rotation on the spindle by bearings at opposite ends of the shell. It is common practice to provide seals between opposite ends of the shell and the spindle to protect the bearings against the ingress of moisture.

Inherent in the above arrangement is the fact that all or many of the rollers will be supported in such a way that they have an upwardly facing seal between the roller shell and the spindle. When the rollers are used in an outside operating environment, moisture can accumulate and can tend to penetrate the seal at the upwardly facing end of the roller. The problem of moisture getting into the bearings is much less through a downwardly facing seal.

A further problem is that the need to contain the conveyor in a tube means that it is necessary to have containing rollers at frequent intervals. This in turn means that the rolling resistance of these containing rollers becomes a substantial factor in determining the power necessary to drive the conveyor.

At least a part of the roller resistance comes from the contact of the seals in the roller.

In seeking to mitigate these drawbacks, the present invention provides a conveyor comprising a conveyor belt, and a plurality of roller assemblies spaced apart in the direction of travel of the belt for containing the conveyor belt in tubular form over part of its length, wherein each roller assembly comprises a mounting frame and a plurality of rollers each supported at one end only by the mounting frame.

Preferably, each roller comprises a spindle, a roller shell, bearing means between the shell and the spindle, the spindle protruding from one end only of the shell, and sealing means between said spindle and said one end of the shell.

Advantageously, the rollers are supported on opposite sides of the mounting frame so that there can be some overlap of the rollers when viewed in the direction of travel of the belt.

Conveniently, at least one of the rollers is arranged with its axis of rotation inclined to a plane normal to the direction of travel of the belt.

The invention will now be more particularly described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a schematic side view of part of one embodiment of a conveyor according to the present invention, and Figure 2 is a longitudinal section taken through one of the rollers of Figure 1, on a much enlarged scale.

Referring firstly to Figure 1, the conveyor shown therein comprises a conveyor belt 10 and a plurality of roller assemblies 11 (only one of which is shown) spaced apart in the direction of travel of the belt 10.

Each roller assembly 11 comprises a mounting frame 12 which supports a plurality of idler rollers 13.

As shown, the roller assembly 11 comprises six rollers 13, three on each side of the frame 12. The rollers 13 are angularly displaced with respect to one another to define a ring which contains the belt 10 in a tubular form and preferably, there is some overlap of the rollers 13 when viewed in the direction of travel of the belt 10.

As shown, all six rollers 13 are of equal length. However, this may not be the case. In most circumstances, the lowest roller will carry the highest load and it may therefore be advantageous to make this roller shorter than the other rollers reduce the load on its bearings and transfer some load to adjoining rollers.

Referring now to Figure 2, each roller 13 comprises a spindle 14 which is fixed at one end only (the left hand end as viewed in Figure 2) to the mounting frame 12 and a roller shell 15 mounted for rotation on the spindle 14 by two ball bearing assemblies 16 and 17.

The bearing assemblies 16 and 17 are supported in cup-shaped recesses 18 and 19, respectively, in opposite ends of the shell 15. The recess 19 is closed by a cover 20 which is sealingly secured to the right hand end of the shell 15. A sealing arrangement, comprising two seals 21 and 22, is provided in the recess 18 to provide a seal between the spindle 14 and the left hand end of the shell 15.

The spindle 14 is fixed to the mounting frame 12 by a mounting bracket 23 (see Figure 1).

The mounting bracket 23 is arranged at the lowermost end of each roller 13 except of course when the roller extends horizontally, and this will reduce the tendency for moisture to enter through the sealing arrangement 21, 22.

Also, by involving the use of only one sealing arrangement instead of two for each roller 13, friction resistance due to the sealing arrangements is halved.

Also, it may be desirable to mount some of the rollers 13 of each roller assembly with their unsupported ends slightly ahead of their supported ends as viewed in the direction of travel of the belt, i.e.

with the axes of some rollers at an angle to a plane normal to the direction of travel of the belt. This is facilitated by rollers supported at one end only and has the advantage that it could reduce the tendency of the belt to "wander" which, in the case of a tubular conveyor, would probably express itself as rotation of the tubular belt.

Of course, the belt is not contained in tubular form over its entire length. It is caused to flatten out at its two ends for loading and discharge, and the return run (not shown) may also be flat. The tubular form of the belt is obtained in conventional manner by progressively rolling the belt first into a trough and then into a tube using a series of appropriately designed roller assemblies.

As described above, the rollers 13 of each roller assembly 11 are mounted on opposite sides of the frame 12. This is however by no means essential and if the rollers 13 are mounted on one side only of the frame 11, the absence of a spindle protruding from one end of the roller shell 15 makes it easier to keep the ends of adjacent rollers close together.

Various other modifications may be apparent to persons skilled in the art without departing from the scope of the invention.

Claims (6)

1. A conveyor comprising a conveyor belt and a plurality of roller assemblies spaced apart in the direction of travel of the belt for containing the conveyor belt in tubular form over part of its length, wherein each roller assembly comprises a mounting frame and a plurality of rollers each supported at one end only by the mounting frame.

2. A conveyor as claimed in claim 1, wherein each roller comprises a spindle, a roller shell, bearing means between the shell and the spindle, the spindle protruding from one end only of the shell, and sealing means between said spindle and said one end of the shell.

3. A conveyor as claimed in claim 1 or claim 2, wherein the rollers are supported on opposite sides of the mounting frame.

4. A conveyor as claimed in claim 3, wherein there is some overlap of the rollers when viewed in the direction of travel of the belt.

5. A conveyor as claimed in any one of the preceding claims, wherein at least one of the rollers is arranged with its axis of rotation inclined to a plane normal to the direction of travel of the belt.

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