GB2199068A - Adjustment of mine conveyor angle by link with mine roof support - Google Patents

Abstract

The mine roof support 10 has an advancing mechanism 12, 13, 16, for connecting the mine roof support to an abutment, for example a mine conveyor 18. Adjustment means 25, 26 is connected between the mine roof support and the conveyor for adjusting the angle of the conveyor with respect to the mine roof support. This in turn makes it possible to adjust the orientation of a mining machine (30 Fig. 2 not shown) mounted on the conveyor 18, with respect to the mine roof support. This makes it possible to reduce the risk of the mining machine 30 colliding with a roof engaging portion (33 Fig. 4 not shown) of the mine roof support, particularly in high seams. <IMAGE>

Description

Nine Roof Supports The Invention relates to mine roof supports.

In longwall methods of mining it is common practice to use the mining conveyor, which runs along the mine face, to fulfil three major functions, the prime function being to convey the mined material, for example, coal from the face workings to the mine roadways, from which the mineral can be transported to the surface.

The other major functions are firstly to provide a guide and supporting track for the mining machine traversing the longwall mine face, and secondly to provide an anchorage for the usual row of mine roof supports placed alongside the mining conveyor in a side-by-side relationship along the mine face.

Thus the conveyor, mining machine, and mine roof supports are important elements in the formation of a fully integrated longwall mining system. The relationship between these three elements is important if the mining operation is to be effective, particularly with relatively high mineral extraction seams of, for example, two metres or more. This is because, the higher the seam, the greater is the risk that the mining machine may foul on one of the mine roof supports if the conveyor is incorrectly aligned, as described in more detail below.

Longwall mining, as the name implies, is a system of underground mineral extraction in which a strip or section of mineral is removed to the height of the mineral bearing strata over the entire length of the face. The height of the mineral bearing strata or seam may for example vary from 0.5 metres to 6 metres. The length of the face may for example vary from 100 metres to 200 metres.

t is most unusual for the mineral bearing strata or seam to be flat over the whole mining area. Regardless of whether the seam is substantially horizontal, or follows an inclined plane, the seam usually undulates in one or more directions. Thus for substantially total extraction purposes the workings must follow the undulations in whatever direction they may take, as the mineral face is advanced and the mineral is removed.

To accomodate these undulations the mine conveyor is generally constructed from a number of rigid sections or pans which are interconnected to provide a limited degree of pivotal movement between adjacent pans in both the lateral and upward directions with respect to the undulating plane of the strata on which the conveyor rests.

One form of pan comprises a pair of channel sections having their mouths facing one another, a central plate being welded between the channel sections. In use a plurality of spaced-apart laterally extending strips or flights, interconnected at their ends by chains for the full length of the conveyor, are pulled over the top of the welded plate by drive means. The underside of the plate provides a return track for the flights and chains. A further plate may be welded between the channel sections to bridge the bottom inward facing flanges of the channel sections to retain the return flights. Attached to the mine roof support side of each conveyor pan is a vertical plate which in use lies between the conveyor and the supports to prevent or reduce spillage of the mined mineral from the conveyor into the path of the supports.

The mining machine runs on the upper flanges of the channel sections. Thus the angle of cut made by the mining machine is dependent upon the attitude of the conveyor as it rests on the mine floor. The cutting operation invariably results in steps being formed in the floor and roof and it can be shown that a progression of these steps, if not corrected, becomes cumulative, with the result that the mine workings drift out of the mineral bearing strata or seam.

Support of the mine roof above the conveyor is achieved by a forwardly projecting cantilever portion of the mine roof support and it is advantageous to support the roof as close to the mineral bearing face as is practical for both safety and the promotion of good mining conditions.

On high seams, where a machine of the ranging drum shearer type is.employed to cut the full height of the seam, albeit in stages, tilting or grading of the conveyor, which may well occur if the conveyor is bridging a step in the mine floor, in turn tilts the upper cutting drum away from or towards the cantilever portion of the roof support. Although the mining machine may have a facility for correcting the angle of the machine with respect to the conveyor, to a limited extent, an upward incline of for example 1 in 7 on the conveyor in the direction of advance of the face will. inevitably cause interference between the upper cutting drum and the cantilever portion of the mine roof support.

The. present invention seeks to overcome or reduce this problem.

Accordingly, the invention provides a mine roof support having an advancing mechanism for connecting the mine roof support to an abutment, for example a mine conveyor, and adjustment means connectible between the mine roof support and the conveyor for adjusting the angle of the conveyor with respect to the mine roof support.

Preferably the adjustment means comprises at least one hydraulic jack extending in a vertical direction or a direction which has a substantial vertical component.

Preferably the or each hydraulic jack is attached to the advancing mechanism.

There may be a first hydraulic jack connected to the advancing mechanism for attachment to the conveyor, to vary the angle of the conveyor with respect to the advancing mechanism, and a second hydraulic jack acting between the advancing mechanism and the mine roof support to vary the angle and/or height of the advancing mechanism with respect to the body of the mine roof support.

In many mining conditions it is unwise to connect an advancing mechanism in the form of a hydraulic jack directly between the conveyor and the mine roof support because the piston rod of the hydraulic jack is likely to be subjected to lateral loads resulting in damage to the jack. It is therefore conventional practice to connect a link, known as a relay bar, between the hydraulic jack and the conveyor, the hydraulic jack being pivotally mounted on the mine roof support. The relay bar transmits the requisite pushing and pulling forces and is also capable of guiding a support into position as the support advances.

The relay bar may be constructed substantially to resist the off-centre loading which would damage a directly coupled piston rod.

Preferably the adjustment means is connected to a relay bar of the support.

Preferably the relay bar is pivotally connected to a substantially horizontally extending hydraulic jack cylinder of the advancing mechanism at one end of the relay bar, the other end of the relay bar having a pivotal connection for attachment to the abutment.

Where the adjustment means comprises two hydraulic jacks, the hydraulic jack which is arranged for connection to the conveycr may have a fixed pivotal connection with the relay bar.

The second hydraulic jack may have a sliding pivotal connection with the relay bar.

Preferably at least the seconc hydraulic jack is double-acting, thus making it possible to lift up the relay bar or hold the relay bar down on to the mine floor, as required.

The invention includes a mine roof support as defined above, when connected to a mine conveyor.

Preferably the pivotal connection between the relay bar and the conveyor, the pivotal ccnnection between the first hydraulic jack and the conveyor, and the pivotal connection between the first hydraulic jack and the mine roof support form the apices of a triangle, the length of two sides of the triangle being fixed while the length of the third side is adjustable.

By way of example, a specific embodiment of the invention will now be described, with reference to the accompanying drawings, in which: Figure 1 is a side view of part of an embodiment of mine roof support according to the invention, attached to a mine conveyor, lying on a substantially horizontal mine floor; Figure 2 is a view similar to Figure 1 but showing the support and conveyor.lying on a mine floor having an upward step; Figure 3 is a view similar to Figure 2 but showing the mine roof support and conveyor lying on'a mine floor having a downward step; and Figures 4 to 6 are side views of the support demonstrating the problem which is substantially overcome by the embodiment.

Referring firstly to Figure 1, part of the body of the mine roof support is illustrated in dotted lines at 10.

The base of the conveyor comprises a pair of parallel, spaced-apart skids, in a conventional manner, the front ends of the skids being interconnected by a substantial metal bridge plate 11.

Mounted between the skids is an advancing mechanism in the form of a hydraulic jack having a cylinder 12 and a piston 13. The front end of the piston 13 is pivotally connected to the bridge 11 at 14. The cylinder 12 is pivotally connected at 15 to a substantial box section relay bar 16. In use the front end of the relay bar 16 is pivotally connected at 17 to a mine conveyor indicated generally at -18. The conveyor comprises a pair of inwardly facing channel members 19 and 20 between which is welded a central plate 21. In use spaced-apart flights (not shown) are drawn along the top of the plate 21 to convey mineral along the plate and the flights return underneath the plate 21. An upwardly extending side plate 22 reduces spillage of mineral into the path of the support 10.

The conveyor 18 and support 10 are advanced in a conventional manner. Before the mining machine passes along the conveyor to cut away a strip of mineral, the support is supporting the mine roof in a conventional manner. Once the mining machine has passed the piston rod 13 is retracted with respect to the cylinder 12.

Since the position of the support is temporarily fixed, the cylinder 12 moves to the left as viewed in Figure 1.

Thus the relay bar 16 also moves to the left, pushing the conveyor 18 up against the newly cut mine face. The support is then freed from the mine roof by lowering its legs lOa, and the piston rod 13 is extended to push the sUpport back to a-position adjacent the conveyor.

Connected between afixed pivot 23 adjacent the front of the relay bar 16, and a fixed pivot 24 on the conveyor plate 22, there is a first adjusting jack 25. It will be apparent that varying the length of this jack will vary the angle between the conveyor 18 and the support 10.

A second adjusting jack 26 is vertically mounted on the bridge plate 11. The arrangement is such that the piston of the jack 26 remains fixed and the cylinder of the jack moves upwardly or downwardly relative to the plate 11. The lower end of the cylinder of the jack 26 is pivotally connected at 27 to a C-shaped bracket 28 through which the relay bar 16 is slidable.

When the floor of the mine is substantially flat as shown in Figure 1, no adjustment of the angle between the conveyor 18 and the support 10 is necessary. However the jack 26 may be used while the support 10 is being advanced to press the relay bar 16 against the floor of the mine, to such an extent that the front end of the support is raised, thus assisting movement of the support over any obstructions such as a build up of fine material in front of the support.

However the main function of the jacks 25 and 26 is to adjust the attitude of the conveyor in the event that steps exist in the floor of the mine. In practice, such steps are nearly always created and an example of an upward step is shown in Figure 2.

In Figure 2, the ram 26 has been retracted from the position shown in Figure 1, thus lifting the right-hand side of the conveyor as viewed in Figure 2, to maintain the conveyor in a substantially horizontal position even though the conveyor is bridging the step 29. Pressure is also applied to the jack 25 to prevent the conveyor 18 (and the mining machine 30 mounted thereon) from tilting in a clockwise direction as viewed in Figure 2.

Figure 3 shows the position when a downward step 31 is encountered. As shown in Figure 3, the rams 25 and 26 have not yet been used to correct the position of the conveyor 18. When it is desired to arrange the conveyor 18 substantially horizontally, in spite of the downward step 31, the ram 26 is extended to press the relay bar 16 against the mine floor, and the ram 25 is retracted to apply downward force to the right-hand side of the conveyor as viewed in Figure 3, hence tilting the conveyor 18 clockwise as viewed in the Figure into a horizontal position.

It will be appreciated that as the relay bar 16 moves in or out with respect to the support 10, an upper flange of the relay bar slides through the C-shaped bracket 28.

Figures 4 to 6 illustrate what would happen if the rams 25 and 26 were not available for correction purposes.

Figures 4 to 6 all illustrate the situation where an upward step 29 is encountered, but in Figure 4 the mining machine is cut in steps in order to mine a seam having an incline of 1 in 13.3, in Figure 5 the incline is 1 in 10, and in Figure 6 the incline is 1 in 7.

In Figure 4, the step 29 causes the conveyor 18 to tilt slightly but the upper cutting drum 32 of the machine does not foul on the leading tip of the cantilever portion 33 of the mine roof support 10.

In Figure 5 the drum 32 is shown as fouling slightly on the cantilever portion 33 but the amount of interference is so slight that it can be accomodated by the conventional adjustment mechanism incorporated in the mining machine 30 itself. If this adjustment is utilised, the drum 32 would take up the position shown in dotted lines at 32a.

In Figure 6 however, the degree of tilting is so great that even if the full mining machine adjustment were used, with the cutting drum 32 taking up the position shown at 32a, there would still be interference with the cantilever portion 33. However, interference can be eliminated by appropriate use of the jacks 25 and 26.

Claims (12)

1. A mine roof support having an advancing mechanism for connecting the mine roof support to an abutment, for example a mine conveyor, and adjustment means connectible between the mine roof support and the conveyor for adjusting the angle of the conveyor with respect to the mine roof support.

2. A mine roof support as claimed in Claim 1, in 'which the adjustment means comprises at least one hydraulic Jack extending In a vertical direction or a substantial vertical component.

3. A mine roof support as claimed in Claim 2, in which the or each hydraulic jack is attached to the advancing mechanism.

4. A mine roof support as claimed in Claim 3, in which there is a first hydraulic Jack connected to the advancing mechanism for attachment to the conveyor, to vary the angle of the conveyor with respect to the advancing mechanism, and a second hydraulic Jack acting between the advancing mechanism and the mine roof support to vary the angle and/or height of the advancing mechanism with respect to the body of the mine roof support.

5. A maine roof support as claimed In any one of the preceding claims, In which the adjustment means Is connected to a relay bar of the support.

6. A mine roof support as claimed In Claim 5, in which the relay bar is pivotally connected to a substantially horizontally extending hydraulic Jack cylInder of the advancing mechanism at one end of the relay bar, the other end of the relay bar having a pivotal connection for attachment to the abutment.

7. A mine roof support as claimed in Clalm 5 or Claim 6, in which the adjustment means comprises two hydraulic Jacks, the hydraulic Jack which is arranged for connection to the conveyor having a fixed pivotal connection with the relay bar.

8. A mine roof support as clalmed In Clalm 7, in which the second hydraulic jack may have a slidlng pivotal connection with the relay bar.

9. A mine roof support as clalmed in Claim 8, in which at least the second hydraulic Jack is doubleacting, thus making It possible to lift up the relay bar or hold the relay bar down on to the mine floor, as required.

10. A mine roof support as claimed In any one of Claims 1 to 9, when connected to a mine conveyor.

11. A mine roof support as claimed in Claim 10, in which a pivotal connection between a relay bar and the conveyor, a pivotal connection between a first hydraulic Jack and the conveyor, and a pivotal connection between the first hydraulic Jack and the mine roof support from the apices of a triangle, the length of two sides of the triangle being fixed while the length of the third side is adjustable.

12. A mine roof support constructed and arranged substantially as herein described, with reference to the accompanying drawings.