GB2207108A - Belt tensioning means in a conveyor system - Google Patents

Abstract

In belt conveyor system which includes a belt tensioning means to tension the conveyor belt 1 of the system, the belt tensioning means comprises: - a moveable tensioner, in the form of a railway carriage 2, and - a frame member 5 having - a belt engaging member 8 which transmits tension to the conveyor belt, and - a braking means. In use the frame member 5 is pivotal between a first position in which no tension is applied to the conveyor belt and the braking means is engaged, and a second position in which tension is applied to the conveyor belt and the braking means is not engaged. <IMAGE>

Description

CONVEYOR SYSTEM This invention relates to a belt conveyor system, and in particular a belt tensioning means for use in a belt conveyor system.

In a known belt conveyor system for use on a sloping roadway the belt tensioning means simply comprises a carriage mounted on rails. The carriage includes a drum around which is wound the belt of the conveyor so that the weight of the carriage acts on the belt of the conveyor to provide the necessary tension in the conveyor belt.

The problems associated with the use of this type of belt conveyor system mainly involve the safety of the system. In particular they relate to the behaviour of the system in the case of apart failure, such as a conveyor belt failure.

With this type of belt conveyor system the only means which maintains the carriage in position is the conveyor belt. In the case of a belt failure this means, there is no physical means which prevents the carriage from travelling down the rails. Therefore, in the event of a belt failure the carriage will travel along the rails down the slope, gathering speed, and eventually crashing into members at the end of the rails, for example, buffers or a mine wall. On its path down the rails it is conceivable that the carriage could pick up either miners or equipment, thereby leading to a possible loss of life or serious damage to mining equipment.

The present invention has been conceived with a view to eliminating, or at least drastically reducing any possible dangers.

In accordance with the present invention a belt conveyor system includes a belt tensioning means which comprises: - a moveable tensioner, and - a frame member having - a belt engaging member which transmits tension to the belt, and - a braking means wherein the frame member is pivotal between a first position in which no tension is being transmitted, to the belt, and the braking means is engaged, and a second position in which tension is being transmitted to the belt, and the braking means is not engaged.

Under normal operating conditions the belt tensioning means is disposed so that the moveable tensioner may travel down a sloped roadway i.e.

acts in the direction of downward motion on the sloped roadway.

In these conditions the net force component which acts upon the conveyor belt is equal to W Sin P where W is the weight of the moveable tensioner and 0 is the angle of the plane of travel of the movable tensioner to the horizontal.

The tension brought about in the belt, therefore, may be varied for any particular roadway by altering the weight of the moveable tensioner.

The moveable tensioner is, preferably, such that the weight thereof may be varied.

In normal operating conditions the weight of the moveable tensioner acts so as to ensure that the braking means is in the second position and, therefore is disengaged. This means that the moveable tensioner is free to move in variance to the weight of load applied to the conveyor belt.

With the braking means so arranged, if failure of the conveyor belt should occur the tension in the conveyor belt is relieved and the braking means is caused to return to its first position and thereby be engaged.

In its first position the braking means acts to prevent movement of the moveable tensioner provided that it is not excessively heavy in relation to the slope of the roadway.

Even if the moveable tensioner is excessively heavy in relation to the slope of the roadway, the net force of the move able tensioner will generally act so as to cause the tensioner to slide, and not roll as in the prior art, down the sloped roadway.

Therefore, the speed of the tensioner down the sloped roadway will be considerably reduced, and the danger will be correspondingly reduced.

The braking means, preferably, also includes a force resisting means.

This force resisting means acts so as to resist the force applied to the conveyor belt and to cause the braking meons to return to the first position when the tension in the conveyor belt is not present.

The moveable tensioner is, preferably, a carriage which is mounted so that it may travel along a set of rails.

The frame member is, preferably, arranged so that it moves in conjunction with the moveable pensioner, and is most preferably, formed as an integral part of the moveable tensioner.

Any suitable braking means may be used with the conveying system, for example held off friction brakes or mechanically interengaging members.

The braking means, preferably, comprises a first member which moves in conjunction with the frame member and a second member which engages with the first member to prevent rotation of the wheels of the carriage.

The first and second members are, preferably, disposed so that the braking force acts centrally on axles disposed between the wheels of the wheeled carriage.

Any suitable interengaging means may be used as the first and second members, for example, interengaging gears, a push bar and cam arrangement or a sprag device which engages rail sleepers.

The belt engaging member may comprise any suitable member which allows relatively unhindered travel of the conveyor belt. This may be, for example, a roller on a bar arrangement or simply a free bar arrangement. However, preferably, the belt engaging member is a drum which is disposed on the frame member so as to allow free movement with relation thereto.

The force resisting means may comprise any means which resists and stores, at least in part, the force applied thereto. This may be an hydraulic jack type arrangement, however is, preferably, a simple mechanical member or members so disposed.

The force resisting means, preferably, comprises at least two resilient members disposed so as to resist tensioning of the conveyor belt, and thereby bring about engagement of the braking means when appropriate.

The invention also includes a belt tensioning means for use with a conveyor belt system as described above.

The invention will now be described, by way of example, with reference to the accompanying drawings in which: Fig. 1 shows a side view of the belt tensioning means in accordance with the invention, and Fig. 2 shows a cut away plan view of the belt tensioning means shown in Figure 1.

A conveyor belt system (not shown) includes: - R conveyor belt 1 - a carriage 2 having wheels 3 mounted so that it may travel along a set of rails 4 - a frame member 5, and - a braking means.

The frame member 5 is pivotally mounted at a pivot 6, to the carriage 2 and is substantially square In shape with a.central orifice 7.

The frame member 5 includes a drum member 8 rotatably mounted on the frame member by means of axle mountings 8a, so that the conveyor belt 1 may be passed through the orifice 7 around the drum 8 and back out through the orifice.

The braking means includes a push bar 9 having two first members 10 mounted thereon and is mounted in brackets 11 disposed centrally of the carriage to run longitudinally thereof and between the axles thereof.

The first members 10 are disposed on the push bar so as to engage, when no tension is applied to the conveyor belt 1, with two cam shaped second members 12 mounted one on each axle of the conveyor belt 1. The cam shaped members 12 are mounted so as to extend circumferentially about the axle on which it is mounted.

The push bar 9 is connected to the frame member 5 by means of a link member 13 so that when no tensioning force is being applied to the conveyor belt 1 by the drum member 8, the first member 10 and second member 12 are interengaged. Therefore the braking means is engaged.

Furthermore, two springs 14 are disposed between a shoulder 15 of the carriage 2 and the frame member 5, so that they resist the force applied to the conveyor belt 1 and act so as to cause the braking means to be engaged when no force is being applied to the conveyor belt.

In operation, the weight W of the carriage 2 means that a force W Sin / where is the angle of the set of rails 4 to the horizontal, is transferred to the conveyor belt 1.

This force should be sufficient to overcome the resistive force of the springs 14, and by means of the drum member 8 the net force thereof is transferred to the conveyor belt 1 when this is disposed thereabouts.

The action of the net force is such that the frame member 5 is pivoted about its pivot 6.

This pivotal movement is transferred by means of link member 13 to the push bar 9 resulting in the disengagement of the first members 10 and the second member 12 from one another.

The braking means is thereby disengaged and the carriage 2 will not be prevented from moving on the rails 4.

Further, the pivotal movement causes the springs 14 to be compressed and thereby energy is stored to help with the return the frame member 5 and engagement of the braking means at the desired time.

When a conveyor belt l fails the tensioning force applied to the conveyor belt is removed and thereby the force causing pivotal movement of the frame member 5 is removed. The energy stored in the springs 14, in conjunction with the force component of the frame member, now causes the frame member 5 to return to its non force applying position. This movement causes the braking means to be engaged and the carriage 2 is thereby prevented from moving along the set of rails 4.

Claims (14)

1. A belt conveyor system which includes a belt tensioning means which comprises: - a moveable tensioner, and - a frame member having - a belt engaging member which transmits tension to the belt, and - a braking means wherein the frame member is pivotal between a first position in which no tension is being transmitted to the belt and the braking means is engaged, and a second position in which tensions being transmitted to the belt, and the braking means is not engaged.

2. A belt conveyor system as claimed in claim 1, wherein the braking means includes a force resisting means.

3. A belt conveyor system as claimed in claim 2, wherein the force resisting means acts so as to resist the force applied to the conveyor belt and to cause the braking means to return to the first position when the tension in the conveyor belt is not present.

4. A belt conveyor system as claimed in any one of claims 1 to 3, wherein the weight of the moveable tensioner can be varied.

5. A belt conveyor system as claimed in any one of the preceding claims, wherein the moveable tensioner has a carriage mounted so that it may travel along a set of rails.

6. A belt conveyor system as claimed in any one of the preceding claims, wherein the frame member is arranged so that it moves in conjunction with the the moveable tensioner.

7. A belt conveyor system as claimed in any one of the preceding claims, wherein a frame member is formed as an integral part of the moveable tensioner.

8. A belt conveyor system as claimed in any one of the preceding claims, wherein the braking means comprises a first member which moves in conjunction with the frame member and a second member which engages with the first member to prevent rotation of the wheels of the carriage.

9. A belt conveyor system as claimed in claim 8, wherein the first and second members disposed so that the braking force acts centrally on axles disposed between the wheels of the wheeled carriage.

10. A belt conveyor system as claimed in any one of the preceding claims, wherein the belt engaging member is a drum which is disposed on the frame member so as to allow free movement with relation thereto.

11. A belt conveyor system as claimed in any one of claims 2 to 10, wherein the force resisting means comprises at least two resilient members disposed so as to resist tensioning of the conveyor belt, and thereby bring about engagement of the braking means when appropriate.

12. A belt tensioning means for use with a conveyor belt system as claimed in any one of the preceding claims.

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

14. A belt tensioning means substantially as hereinbefore described with reference to the accompanying drawings.