GB2077211A - Conveyor Assemblies for Mine Workings - Google Patents

Abstract

A conveyor assembly for a mine working is driven by a drive motor to which power is applied. The conveyor assembly comprises a retarder device, e.g. a brake shoe 32, associated with the drive motor, which is normally urged into an inoperative condition. However in the event of an interruption in the power applied to the drive motor, the retarder device applies a braking force to a driving shaft 30 to stop the conveyor over a short distance. <IMAGE>

Description

SPECIFICATION Improvements Relating to Conveyor Assemblies for Mine Workings This invention is concerned with improvements relating to conveyor assemblies for mine workings.

A conveyor assembly for a mine working conventionally comprises a conveyor, comprising two spaced apart sprockets, and an endless chain extending between the sprockets, scraper bars being provided along the chain at interals, to move such mineral material along the conveyor as the sprockets in the operation of the assembly rotate.

Drive means is provided for at least one of the sprockets, conventionally in the form of an electric motor, rotating the sprockets through intermediate gearing. In a face-side conveyor, where the conveyor is long, and/or large quantities of cut mineral material are required to be moved, the motor is often in excess of one hundred horse-power, and a large gearbox is utilised. Thus, the mass of the moving parts of the conveyor assembly may be very high.

It is a requirement, that manually operable means be provided, whereby operation of the drive means may be terminated when this is required, for example for reasons of safety. Such manually operable means may be operable either from a control position, or by pull-keys located at spaced intervals along the length of the conveyor.

One of the problems encountered in present conveyor assemblies for underground mine workings is the time required for the conveyor to come to a halt. This is generally in excess of 1 metre, and particularly where the conveyor assembly is moving mineral material down a gradient, may be substantially higher than this.

This means that, when it is desired to terminate operation of the conveyor assembly in an emergency, the time actually taken by the assembly to come to a halt may not prove to be sufficiently small.

It is one of the various objects of this invention to overcome this problem.

According to this invention there is provided a conveyor assembly for a mine working, comprising a conveyor, drive means for the conveyor, and power applying means for the drive means, the conveyor assembly comprising a retarder device adapted to apply a braking force to the drive means, in the event of an interruption of power applied to the drive means.

In theory, the retarder device may be urged to an operative condition by an applicator means in which it applies a braking force to the drive means, and could be retained in an inoperative condition by the action of the power applied to the drive means by the power applying means, such as by magnetically operated devices, and on interruption of the power applied to the drive means, said applicator means causes the retarder device to apply a braking force to the drive means.

However since to dissipate the momentum of the conveyor assembly in a desirably short time, a high braking force would be required, and such a solution suffers from the disadvantages of high power consumption to retain the retarder device inoperative.

Thus preferably an external supply of fluid under pressure is utilised to maintain the retarder device inoperative, preferably applied through a solenoid valve retained in a first condition (in which it causes the fluid under pressure to be directed in such a manner as to retain the retarder device inoperative) by the power applied to the drive means by the power applying means. The solenoid valve may be urged into a second condition by a light spring, which condition it adopts in the event of an interruption of the power applied to the drive means. Thus, the solenoid valve in its second condition relieves the forces maintaining the retarder device in its inoperative condition, allowing the retarder device to be moved to its operative condition, conveniently by the use of heavy duty compression springs.

Alternatively the retarder device may be retained in an inoperative position by a restraining device, and the applicator means may be afforded by fluid pressure devices powered by an external supply of fluid under pressure. Thus, such fluid under pressure may be applied to the applicator means through a solenoid valve retained in a first condition, in which the applicator means is unpowered, by the power applied to the drive means by the power applying means. The solenoid may be urged into a second condition by a light spring, which condition it adopts in the event of an interruption of the power applied to the drive means. Thus, the solenoid valve when in its second condition causes fluid under pressure to be applied to the applicator means, causing the retarder device to be moved to its operative condition against the action of the restraining device.In such circumstances, the restraining device may be afforded by relatively light springs.

There will now be given a detailed description, to be read with reference to the accompanying drawings, of a conveyor assembly which is an embodiment of this invention which has been selected for the purposes of illustrating this invention by way of example.

In the accompanying drawings: Figure 1 is a plan view of part of the conveyor assembly; Figure 2 is a schematic view illustrating a retarder device of said conveyor assembly; and Figure 3 is a side elevational view of an effective retarder device.

The conveyor assembly which is the illustrated embodiment of this invention is a face-side conveyor, comprising two spaced sprockets, only one of which, numbered 6 in Figure 1, is shown, said sprockers being spaced apart by a distance which may be 100--300 metres. Extending around the sprockets are the two chains 20, 22 and extending between these at spaced intervals are scraper bars, adapted to move to cut mineral material over the floor F of the conveyor. The conveyor assembly comprises drive means for the conveyor, comprising an electric drive motor 1 6, and gearing 18 adapted to drive the sprocket 6 through a drive shaft 8.The drive motor 16 is provided with a supply of electricity 22 and means is provided at suitable positions spaced along the conveyor, whereby the supply of electricity may be interrupted, when it is necessary to stop the conveyor.

Located at a suitable place, conveniently within the housing 20 of the gearbox 18, is a retarder device, shown in Figure 2 in association with one of the shafts, numbered 30, of the gearbox, and which during operation of the conveyor is rotating at a relatively high speed. Thus, preferably the shaft 30 is one which is fairly close to the electric motor 16.

The retarder device comprises a brake shoe 32, comprising a lining 34, and which is urged into an operative position in contact with the peripheral surface of a flywheel 31 of the shaft 30 by heavy duty compression spring 36. However acting on the brake shoe 32, in a direction opposite to the springs 36, are two fluid-operated piston/cylinder devices 38. Fluid under pressure is supplied to the devices 38 via a spool valve 40, the position of which is determined by a solenoid 42. When the supply of electricity to the drive motor 1 6 is not interrupted, the solenoid 42 moves the spool valve 40 to the position shown in Figure 2, in which fluid under pressure from a supply 44 (conveniently derived from the supply of fluid under pressure utilised to work adjacent roof support units) is applied to the devices 38.

However in the event of an interruption in the supply of electricity to the drive motor 1 6 a light spring moves the solenoid to a second condition, in which the spool valve 40 vents the devices 38 to a sump 46. The brake shoe 32 is then moved rapidly, and a large force, against the flywheel 31 and applies a braking force thereto.

Preferably the brake shoe 32 is associated with a second brake shoe which also acts on the flywheel 31 in an opposite direction, to prevent an unbalanced force from being applied to the flywheel 31. However, for reasons of simplicity, this second brake shoe has not been shown in Figure 2.

Alternative to the use of the retarder device illustrated in Figure 2, a matrix spring applied, pressure release brake may be utilised, specifically of the kind illustrated in Figure 3.

Thus, the drive shaft 30 may carry a number of annular brake discs 50, the matrix brake comprising a shoe 52 carrying a series of complementary annular braking discs 54, the shoe 52 being urged into a position of braking engagement with the discs 50 by heavy duty springs 36'. By the admission of fluid under pressure through a conduit 56 to an annular chamber 58, the shoe 52 may be urged into an inoperative position: however, when the supply of fluid under pressure to the chamber 58 is terminated, and the chamber 58 is vented, the springs 36 urge the shoe 52 into an operative position to apply a braking force to the drive shaft 30'.

By the use of the retarder device shown in Figure 3, it has been found possible to arrest the conveyor between a distance of 0.5 and 1.0 metres. A distance lower than 0.5 metre is undesirable, since this would produce shock loading on the various elements of the conveyor assembly, whilst the distance of 1.0 metres represents a highly desirable, short stopping distance.

Additionally, when the electricity supply is restored, the small time taken to repressurise the devices 38 corresponds to the time taken for the electric motor 1 6 to build up sufficient momentum to take up the strain on the conveyor.

In an alternative embodiment (not shown) the retarder device is urged into an inoperative position by light compression springs, and the applicator means is afforded by fluid pressure devices, connected through a solenoid valve to a source of fluid under pressure, such as the fluid utilised to power the roof support units. The solenoid valve is urged into a second condition by a light spring and is retained in a first condition, in which the fluid pressure devices are retained inoperative, by the power applied to the drive means by the power applying means. In the event of an interruption in such power, the solenoid moves into its second condition, causing fluid under high pressure to be delivered to the fluid pressure devices, moving the retarder device to its operative condition against the action of the restraining means.

Although the invention has been described in relation to a face-side conveyor, which are conventionally massive systems, the invention may be utilised to advantage on other conveyor systems found in a mine working. For example, although a stage loading conveyor may be only in the order of 30 metres in length, driven by a motor for example of 64 h.p. such conveyors are frequently used in conjunction with crushing mechanism. Thus, the retarder device of this invention may be utilised in such conveying assemblies with considerable advantage to safety.

By the use of this invention, and in particular by virtue of the use of a retarder device which is actuated by means of the fluid under pressure utilised to power the roof support units, wheri the power supply to the drive means 16 is terminated, the retarder device may be fitted within the conventional gearbox utilised in an armoured face conveyor. In this manner, the problems of creation of heat, and the resultant fire risk, which is particularly dangerous in an underground mine working, may be readily be shielded.

Claims (12)

Claims

1. A conveyor assembly for a mine working, comprising a conveyor, drive means for the conveyor, and power applying means for the drive means, the conveyor assembly comprising a retarder device adapted to apply a braking force to the drive means, in the event of an interruption in the power applied to the drive means.

2. A conveyor assembly according to Claim 1 comprising applicator means to urge the retarder device to an operative condition in which it applies a braking force to the drive means.

3. A conveyor assembly according to Claim 2 wherein the applicator means comprises heavy duty compression springs.

4. A conveyor assembly according to one of Claims 2 and 3 wherein the retarder device is retained in an inoperative position by the action of the power applied to the drive means by the power applying means, and on interruption of the power applied to the drive means said applicator means causes the retarder device to apply a braking force to the drive means.

5. A conveyor assembly according to one of Claims 2 and 3 wherein the retarder device is retained inoperative by an external supply of fluid under pressure.

6. A conveyor assembly according to Claim 5 wherein said external supply of fluid under pressure is applied through a valve, retained in a first condition in which it causes the fluid under pressure to be directed in such a manner as to retain the retarder device inoperative, by the power applied to the drive means by the power applying means, an interruption in the application of power to the drive means causing the valve to move to a second condition, in which the applicator means urges the retarder device to its operative condition.

7. A conveyor assembly according to Claim 6 wherein said valve is a solenoid valve, urged to its second condition by a spring.

8. A conveyor assembly according to Claim 2 wherein the applicator means comprises fluid pressure devices, and the retarder device is retained inoperative by springs.

9. A conveyor assembly according to Claim 8 wherein fluid under pressure is applied to said fluid pressure devices through a valve, retained in a first condition in which said fluid pressure devices are inoperative by the power applied to the drive means by the power applying means, an interruption in the application of power to the drive means causing the valve to move to a second condition, in which fluid under pressure is applied to said fluid pressure devices, and said fluid pressure devices operate to move the retarder device to its operative condition.

1 0. A conveyor assembly according to any one of Claims 5 to 9 wherein the retarder device is urged to apply a braking force to the drive means, or is restrained from applying a braking force to the drive means, by the use of fluid under pressure utilised to power roof support units adjacent to the conveyor assembly.

11. A conveyor assembly according to any one of the preceding claims wherein the retarder device is operative in relation to a drive shaft of a gearbox of the conveyor assembly.

12. A conveyor assembly for mine working, constructed and arranged substantially as hereinbefore described with reference to the accompanying drawings.

1 3. Any novel feature or novel combination of features hereinbefore described and/or shown in the accompanying drawings.