GB2201986A - Mine roof support with face sprag - Google Patents

Abstract

A mine roof support comprises a roof engaging structure 10 having a leading end at 14, and an additional support device 11 having first 36 and second 34 ends, the additional support device being movable between an operating position in which the first end 36 is positioned below the second end 34 and a stowed position in which the first end 36 is positioned adjacent to the leading end of the roof engaging structure. <IMAGE>

Description

MINE ROOF SUPPORTS This invention relates to mine roof supports and particularly, though not exclusively, to mine roof supports for use in the longwall method of mining.

In the longwall method of mining coal and other minerals a working mine face, which may be up to 250 metres long and between 1.5 and 5 metres In height Is repeatedly traversed by a mining machine which removes a strip or web of mineral durlng each traverse. Each strip or web may be up to 1 metre in thickness. The mined mineral Is subsequently removed from the working area by a mine conveyor which Is also used as a track along which the mining machine travels.

To support the mine roof during the removal process, It is common practise to utilise hydraulically operable self advancing mine roof supports which are adapted to be attached to the aforesaid conveyor. Using the conveyor as an anchorage, the supports are advanced relative thereto after the removal of the strip or web of mineral.

Prior to the advance of the mine roof supports, there Is a short period of time during which the newly cut roof Is unsupported by the roof engaging canopies of the mine roof supports. To overcome this problem each roof support may be equipped with a forepoling device which can be extended from the roof support to support the newly exposed roof until such time as the mine roof support is advanced, to take up a new supporting location with the foremost part of the canopy close to the mineral bearing face. As the roof support moves forward, the assoclating forepol ing device Is retracted.

In an alternative method of mining known as the immediate forward support or l.F.S. system, there Is no forepoling device. Instead, each self advancing support Is advanced immediately after the passage of the mining machine, prior to the next cut being taken and before the conveyor Itself Is advanced.

When poor mining conditions exist, for example where the mineral is frlable and difficult to work without the mineral face or the strata fragmenting Into small pieces If unsupported, It is sometimes a requirement to support the upwardly extending mineral face by means of a face sprag which usually takes the form of a substantially vertical plate like element which Is pressed against the face from each support by a hydraulic Jack. Each sprag device is usually retracted as the associated mine roof support is advanced, the sprag device normal ly being retracted Into a stowed position on the underside of the foremost part of the prlmary roof engaging structure, to which it Is pivotly attached.

The face sprag Is usually connected to the foremost part of the roof engaging structure when operating an l.F.S. system of mining or to the forepoling device of a conventlonal type of self advancing mine roof support.

With known face sprags, it Is conventional to attach pivotally the upper end of the face engaging plate to elther the leading edge of the roof engaging structure, or to the forepol ing device and to construct the sprag device in such a manner that the sprag plate when in its stowed position horizontally under the roof engaging structure has Its upper end towards the mineral face and its lower end, i.e., when operatlonal, towards the rear part of the mine roof support. Thus It can be envisaged that when moving from Its functional to Its stowed position and vice versa, the lower end of the sprag plate describes an arc or curved path substantially about the pivotal connection.

This known type of face sprag has two maJor disadvantages as follows: (a) If the means latching or retaining the sprag plate In its stowed position fails, the plate can swing down from the underside of the roof engaging structure and in so doing may strike and inJure any face worker located at the support where the fault occurs and In the path of the then swinging plate.

(b) If a relatively high conveyor spill plate Is attached to the goaf side of the conveyor, the top of this spillage plate may obstruct the path of the sprag plate when moving to or from its operating position.

This would result in the sprag plate not reaching the mine face or alternatively not attalning its stowed positlon and remaining on the face side of the spillage plate preventing the free passage of the mining machine along the face.

The invention seeks to elIminate or reduce the above mentioned problems.

The Invention provides a mine roof support comprising a roof engaging structure having a leading end, and an additional support device having first and second ends, the additional support device being movable between an operating position in which the first end Is positioned below the second end, and a stowed position in which the first end is positioned adjacent to the leading end of the roof engaging structure.

Preferably, in the operating positlon, the sald second end Is positioned adjacent to the leading end of the roof engaging structure.

The additional support device may have a substantially planar surface for engagement with a surface of the mine workings to be supported.

The additional support device may for example comprise an elongate substantially flat surface element.

Preferably, in the stowed positlon, the elongate flat surface element lies underneath and substantially parallel to the roof engaging structure.

Preferably, hydraulic Jack means is provided to move the additlonal support device between its operating and stowed positions.

Means may be provided for operating the hydraulic jack means manually.

Means may be provided for operating the hydraulic Jack means as one of a combination of operations of the mine roof support, for example, including the advancing of the support.

The mine roof support may be such that durlng movement of the additional support device between its operating and stowed position, the said second end travels substantially horizontally, while the said first end has a substantlal component of movement in the vertical direction.

To define the path of travel of the additional support device between its operating and stowed position, the additlonal support device Is preferably connected to a part of the mine roof support by guide means.

The gulde means comprlse one or more pivotal links Interconnecting the additional support device and the part of the mine roof support.

For example, there may be a pivotal 1 ink, which, when the additional support device Is In a substantially vertical operating position, interconnects the leading end of the roof engaging structure and a first pivot point In between the ends of the additional support device, the hydraulic jack means extending between the roof engaging structure and a second pivot point positioned above the said first pivot polnt.

In an alternative arrangement, gulde means may be provided on the roof engaging structure which cause the sald second end of the additional support device to travel along guides in a direction towards the rear of the support, while the said first end Is guided by further guides into a positlon adJacent to the leading end of the roof engaging structure.

Preferably, the further guides are positioned lower than the point of attachment of a single hydraulic Jack.

More than one hydraulic Jack may be used.

The additlon support device may be movable to support not only the upwardly extending mine face but also the roof of the mine working.

The stowed position Is preferably such that the additional support device Is removed from its operating position to a location on the mine roof support where it neither obstructs the passage of mine workers nor the passage of a mining machine along the face of the mine workings. The invent ion Includes a further embodiment which enables a shorter ram to be used, and In particular, enables the mountings and operating components of the additional support device to be neatly housed underneath an extension portion of the roof engaging structure, for example an articulated bar.

According to this embodiment, the additlonal support device Is connected to the roof engaging structure by a pair of links each link being connected at one of its ends to the roof engaging structure and connected at the other of its ends to the additional support device, there being extensible drive means connected between an upper part of the mine roof support and at least one of the links. One link may be substantially straight and the other link may have cranked ends.

Preferably the sald one link lies below the said other link.

Preferably, the links are such that in the stowed positlon of the additional support device, the said other link extends from a pivot point on the roof engaging structure downwardly towards the said one link, then extends substantially parallel to the said one link, and finally extends downwardly past one end of the sald one link to a pivot point on the additional support device.

The links may be pivotally connected to the leading end of an extension portion of the roof engaging structure.

By way of example, specific embodiments of the invention will now be described, wlth reference to the accompanying drawings In which ; Flgure 1 is a side view of a first embodiment of mine roof support according to the Invent ion, with its additional support device in an operating position to support a mine face; Figure 2 is a vlew similar to Figure 1 but showing the additional support device in Its stowed position; Figure 3 is a perspective view showing the rear face of the additional support device of Flgures 1 and 2; Flgure 4 Is a diagram comparing the paths of travels of a conventional sprag and the additional support device of the embodiment shown In Flgures 1 to 3;; Flgure 5 is a diagram illustrating the paths of travel taken by the first and second ends of the additional support device of the first embodiment; Figure 6 Is a vlew similar to Figure 1 but Illustrating a second embodiment of mine roof support according to the invention; Figure 7 is a side vlew of part of the support, showing the additional support device In each of Its two positions; Flgure 8 is a front vlew sowing In more detail how the additlonal support device is linked to the roof engaging structure; and Figure 9 is a side vlew illustrating how the additional support device travels between its two positions.

In Figure 1 there Is shown a roof engaging structure 10 of an l.F.S. system self advancing mine roof support. There is also an additional support device in the form of a sprag plate 11 which is pivotly attached to the roof engaging structure 10 by a pair of links 12 13.

The links 12, 13 are pivotly attached to the roof engaging structure 10 by hinge pins (not shown) at 14, and to the sprag plate 11 by hinge pins (not shown) at 15,16.

A double telescopic hydraulic Jack 17 Is pivotly connected to the roof engaging structure at 18 and to the sprag plate at 19.

Preferably, the hydraulic jack 17 Is double acting.

The sprag plate 11 has two proJecting lugs which define the pivot points 15,16 The lugs are positions at the outer vertical edges 20,21 of the sprag plate, such that the outer edges 20,21 may pass between the links 12, 13 when the sprag plate 11 moves from a vertical to a horizontal positlon l.e. from Its operating to its stowed position.

The sprag plate 11 also has two additlonal lugs 22,23 best shown In Flgure 3 for attachment to the Jack 17.

The lugs 22,23 are positioned above the lugs defining pivot polnts 15,16, when the sprag plate Is in Its operating position, but must also be so positlon as to provide an adequate distribution of load applled by the Jack 17 on the surface to be supported.

At that point in the mining cycle where the removal of a strip of mineral from the mine face commences, the mine roof support is set or urged against the mine roof adjacent to the mining conveyor with the leading end of the roof engaging structure 10 close to the mineral bearing face, extending above the conveyor In the manner of a cantilever. The face sprag plate 11 is, at this stage, held against the face by the hydraulic Jack 17, in the position shown in Flgure 1, thus preventing any mineral breaking away from the mine face.

The containment of the mine face in Its vertical state contributes to the support of the roof Immedlately above the mineral which is to be removed during the next cutting passage of the mining machine.

As the mining machine traverses the face, travelling past a row of Identical supports, the sprag plates 11 are successively retracted to their stowed positions to enable the machine to remove a strip of mineral unobstructed by the sprag plate 11 and/or the links 12,13. A mine operator walks along the face ahead of the mining machine retracting the sprags In advance of the mining machine as necessary.

It will be seen from Flgure 2 that In the stowed position, a first end 36 of the sprag plate 11 lies adJacent to the leading end of the roof engaging structure. In the operating position shown in Flgure 1 this end 36 lies vertically below the end 34.

Figure 5 Illustrates the path 35 followed by the end 34 and the path 37 followed by the end 36. Figure 4 shows various positlons of the ends 34 and 36 and it will be seen that the plate 11 obstructs the working area underneath the roof engaging structure to a much lesser extent than a conventional pivotly mounted sprag plate, the lower end of which would follow the curved path 38 shown In Figure 4.

When the machine has passed each self advancing mining roof support the support Is advanced and reset to support the newly exposed part of the mine roof. A second mine working operator responsible for the advancing the support will also set the face sprag to the newly exposed mine face.

Whichever system of mining is used the face sprag may be set to the mine face at all times save for such brief perlod when the mining machine is operating In the vicinity of the self advancing mine roof support to which the face sprag is attached.

When an operator retracts the face sprag 11 from the face to its stowed position, the hydraulic Jack 17 is selectively operated from a valve conveniently located on an adJacent mine roof support. The Jack 17 being affixed to the roof engaging structure at 18 causes the sprag plate 11 and the links 12,13 to turn about the pivotal connection 14. Continued retraction causes the edges 20,21 of the sprag plate 11 to pass between the inner faces of the links 12,13 and further retractlon of the Jack 17 Is continued until the sprag plate 11 is stowed on the underside of the roof engaging structure 10 as shown in Figure 2.

When the sprag plate moves from Its operating position, the end 36 has a substantlal component of vertical motion. It will be seen from Figure 4 that the equlvalent end of an equivalent conventional sprag plate will have a substantial component of movement in the horizontal direction. This means that It Is far more likely than the conventional sprag plate will catch on any conveyor spil lage plate. Furthermore, any mine operator standing underneath the roof engaging structure 10 is likely to be In the area 39 shown in Figure 4. If the sprag plate were to accidentally fall, it Is far more likely that a conventlonal sprag plate would strike and inJure the operator than the sprag plate forming the subJect of this embodiment.

turning now to Flgure 6, the forward part of roof engaging structure 10 In this embodiment is provided with slotted guldes 24 in which slide pivot mountings 25 for the second end of a sprag plate 26. Also sliding in the guldes 24 are pivots 27 for a guide link 28. A further link 29 is pivotly attached to the roof engaging structure 10 at 30 and to the links 28. Where the links 28 and 29 are pivotly connected, there is a palr of gulde rollers 31. A hydraulic Jack (not shown) is connected between the sprag plate 26 and the roof engaging structure 10. When this jack is retracted, the said second end of the sprag plate Is drawn along the guides 24, the plate 26 gradually moving Into a horizontal position, during which movement the rollers 31 engage wlth the edges of the sprag plate 26.Continued retraction of the Jack engages the pins 25 and 27 which in turn lifts the rollers 31 In the upward direction and in turn lifts the sprag plate 26 Into its stowed position within the roof engaging structure 10.

When moving the face sprag Into Its operating positlon, the weight of the sprag plate 26 on the rollers 31 causes the link 29 to adopt a vertical positlon and the pin 27 thus slldes along the guldes 24 towards the front part of the roof engaging structure.

Figures 7 and 9 show part 40 of the roof engaging canopy of this embodIment of mine roof support.

Plvotally connected to the canopy at 41 is an articulated bar 42. A face sprag 43 Is pivotally connected to the bar 42 by an upper link 44 and a lower link 45.

As can be seen from Figure 8, the upper link 44 In fact comprises a pair of spaced apart links, extending between rlbs 46 on the bar 42 and rlbs 47 on the sprag 43.

The lower link 45 also, in practice, comprises a pair of spaced apart links 45, which extend from brackets 48 on the bar 42, and ribs 49 on the sprag 43. The two pivot points 50,51 on the sprag 32 are very close together, as can be seen from Figure 7.

The ;upper I ink 44 has cranked ends, as can clearly be seen from Figure 7, and these cranked portions are arranged so that when the sprag 43 Is in its stowed position, as shown in full lines in Figure 7, the upper link 44 extends from a pivot polnt 52 downwardly towards the link 45, then extends substantially parallel to link 45, and finally extends downwardly again past the lower link pivot point 50, to the upper link pivot point 51.

A short hydraulic ram 53 is mounted between the roof engaging canopy 40 and a central part of the link 44. When the ram is extended, the sprag 43 travels from the stowed position to the operating positlon, gulded by the links 44 and 45. In the operating position, the links 44 and 45 have the position shown In chaln lines shown In Figure 7.

Figure 9 illustrates In more detall the way in which the sprag 43 moves between its two positions. The first end of the sprag 43 initially drops downwardly following the path indlcated by the dotted line 54 while the second end of the sprag 43 Initially rises sllghtly as shown by the dotted line 55 and then follows the arcuate path 546. Once the sprag has reached the generally upwardly extending position shown at 57 it then travels forwardly to its working position.

The shaded area 58 in Figure 9 Illustrates the extra, unobstructed, safe working area which is provided, compared wlth a simple pivotally mounted sprag swinging In an arc from Its working position to its stowed position.

The invention Is not restricted to the details of the foregolng embodiment.

For example, the extent of movement of the Jack 17 shown In Figure 1 may be such that movement of the sprag plate 11 may be continued through the vertical position, In a clockwise directions as shown In Flgure 1, so as in certaln circumstances the sprag plate may act as an extension of the roof engaging structure, to support the mine roof, as opposed to the mine face, In the same manner as a forepoling structure.

The contents of all papers and documents filed concurrently with this specification are incorporated hereln by reference.

All of the features disclosed In this specification (Including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined In any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel combination, of the features disclosed In this specification (Including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

Claims (22)

1. A mine roof support comprising a roof engaging structure having a leading end, and an additional support device having first and second ends, the additional support device being movable between an operating positlon In which the first end is positioned below the second end, and a stowed position in which the first end Is positioned adjacent to the leading end of the roof engaging structure.

2. A mine roof support as clalmed In Claim 1, In which, in the operating position, the said second end is positioned adJacent to the leading end of the roof engaging structure.

3. A mine roof support as clalmed in Claim 1 or Claim 2, In which the additional support device has a substantial ly planar surface for engagement wlth a surface of the mine workings to be supported.

4. A mine roof support as claimed In Claim 3, in which the additional support device comprises an elongate substantlally flat surface element.

5. A mine roof support as clalmed In Claim 4, In which the elongate flat surface element lies underneath and substantlally parallel to the roof engaging structure In the stowed position.

6. A mine roof support, as claimed in any one of the preceding Claims, In which hydraulic Jack means is provided to move the additional support device between its operating and stowed positions.

7. A mine roof support as claimed In Claim 6, In which means are provided for operating the hydraulic Jacks manually.

8. A mine roof support as claimed In Claim 6 or Claim 7, in which means are provided for operating the hydraulic Jack means as one of a combination of operations of the mine roof support, for example, Including the advancing of the support.

9. A mine roof support as claimed in any one of the preceding claims, such that during movement of the additional support device between Its operating and stowed position, the said second end travels substantlally horizontally, while the sald first end has a substantial component of movement in the vertical direction.

10. A mine roof support as clalmed in any one of the preceding Claims In which, to define the path of travel of the additional support device between Its operating and stowed position, the additional support device Is connected to a part of the mine roof support by gulde means.

11. A mine roof support as clalmed in Claim 10, in which the guide means comprlses one or more pivotal links interconnecting the additlonal support device and the part of the mine roof support.

12. A mine roof support as claimed in Claim 11, in which there Is a pivotal link, which, when the additional support device is in a substantlally vertical operating position, Interconnects the leading end of the roof engaging structure and a first pivot point In between the ends of the additional support device, the hydraulic Jack means extending between the roof engaging structure and a second pivot point positioned above the said first pivot point.

13. A mine roof support as claimed In Claim 10, in which guide means are provided on the roof engaging structure which cause the said second end of the additional support device to travel along guides in a direction towards the rear of the support, while the said first end Is guided by further guides into a position adJacent to the leading end of the roof engaging structure.

14. A mine roof support as clalmed in Claim 13, in which the further guides are positioned lower than the point of attachment of a single hydraulic Jack.

15. A mine roof support as claimed in any one of the preceding claims, in which the additional support device Is movable to support not only the upwardly extending mine face but also the roof of the mine working.

16. A mine roof support as claimed in any one of the preceding claims, in which the stowed position Is such that the additional support device Is removed from its operating position to a location on the mine roof support where it neither obstructs the passage of mine workers nor the passage of a mining machine along the face of the mine workings.

17. A mine roof support as claimed in Claim 1, in which the additlonal support device is connected to the roof engaging structure by a palr of links each link being connected at one of its ends to the roof engaging structure and connected at the other of its ends to the additional support device, there being extensible drive means connected between an support part of the mine roof support and at least one of the Inks.

18. A mine roof support as claimed In Claim 17, link which one link is substantially straight and the other llnk has cranked ends.

19. A mine roof support as clalmed In Claim 17 or Claim 18, In which the sald one link lies below the sald other link.

20. A mine roof support as clalmed In Claim 17, in which the links are such that in the stowed position of the additional support device, the said other link extends from a pivot point on the roof engaging structure downwardly towards the sald one link, then extends substantially parallel to the said one link, and finally extends downwardly past one end of the sald one I ink to a pivot point on the additional support device.

21. A mine roof support as claimed in any one of Clalms 17 to 19, in which the links are pivotally connected to the leading end of an extension portion of the roof engaging structure.

22. A mine roof support constructed and arranged substantlally as hereln described, with reference to Flgures 1 to 5, or Flgure 6, or Figures 7 to 9 of the accompanying drawings.