The invention relates to means that will enable support of the hanging wall in an underground mine during the installation of rock anchors. BACKGROUND TO THE INVENTION

In the development of underground mines, a problem exists in the region between the supported and unsupported hanging wall. To advance a mine working, this region needs to follow the progress of the blasting operations with the required conversion of unsupported (man-free) zones into properly supported areas of the mine.

The installation of rock anchors (which may, for example, be of the bolt-, resin-, inflatable-, or tendon-type) requires drilling and insertion into an unsupported or less than optimally supported portion of the hanging wall. There is a high risk of harm or fatality in performing these installation operations.

Temporary supports are in some cases used to mitigate this risk. These may take the form of freestanding, portable props. The installation of such props under an unsupported portion of the hanging wall, however, bears its own risks for the same reason and the support afforded is relatively localized.

There are also some mechanized drill rigs (capable of drilling the hanging wall) that carry a support prop adjacent the drill boom. The support afforded by such a prop may, once again, be relatively localized. In other cases the props carry a heavy top end construction in order to provide a wider area of support above the boom but this is considered a cumbersome feature and limitation for any other drilling operations (at the face or into sidewalls) where the support feature is not required.

Providing adequate support and to provide overhead protection from rock falls in the unsupported workings of a mine to safely install rock anchors into the hanging wall requires some degree of specialized equipment which is then less practical in use where the support is not required.

OBJECT OF THE INVENTION

It is an object of the invention to provide apparatus that will at least partially alleviate the problem referred to or at least certain aspects thereof.

SUMMARY OF THE INVENTION

In accordance with the invention there is provided hanging wall support apparatus comprising: an openwork screen structure including a plurality of suitably rigid supports;

the openwork screen structure securable to a single extendable prop with the supports extending outwardly about the prop; and

a hanging wall engaging structure secured to the prop for engagement with a hanging wall.

The invention provides for the prop to be provided at a substantially central position relative to the openwork screen structure.

Further features of the invention provide for hanging wall support apparatus as defined: in which the supports extend upwardly from a position spaced apart from a leading end of the extendable prop; which has four supports arranged as two pairs of supports respectively secured to opposite sides of the extendable prop; in which the supports provide spaced apart rock engaging components of the hanging wall engaging structure; and which includes a spike on a leading end of the extendable prop.

Further features of the invention provide for hanging wall support apparatus as defined: in which the openwork screen structure includes a plurality of connectors secured between the supports; in which the connectors are flexible; in which the connectors are arranged as a net; in which the connectors are provided by webbing; in which the connectors are provided by wire rope; in which the openwork screen structure is provided by a grid of rigid components; in which the openwork screen structure is provided by a suitable metal plate with openings formed therethrough.

Further features of the invention provide for hanging wall support apparatus as defined: in which the supports of the openwork screen structure are movably connected to the extendable prop; in which each of the supports is pivotably secured to the extendable prop through an articulated connection that affords limited pivoting; and in which each support includes a joint fitted with a rigid spring extending over the joint to return the support to a preloaded position.

A further feature of the invention provides for hanging wall support apparatus as defined: in which the openwork screen structure is arranged with an access opening that is positioned for passage of a drill steel and installation of a rock bolt.

Further features of the invention provide for hanging wall support apparatus as defined: in which the extendable prop is provided on a drill rig; in which the extendable prop to is provided at a front end of a beam supporting at least one pivotably mounted rock drill boom on a development end drill rig; in which the extendable prop to be provided on a roof bolter rig; in which the extendable prop provides a telescopic boom for a rock drill; in which the extendable prop is configured to sting a hanging wall; in which the beam of the drill rig includes an extendable support leg for engagement with a footwall. The term "openwork screen structure" should be understood to include: a combination of parts or components or members that are secured in relation to each other to define openings, gaps or spaces therebetween; and/or

a net; and/or

a grid; that prevents to a suitable and/or required degree the passage of rocks that work loose from a hanging wall to provide a screen or barrier.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features of the invention will become more apparent from the following description of embodiments of the invention, made by way of example, with reference to the drawings, in which: shows a side view of a rock drill boom fitted with the apparatus of the invention;

shows a perspective view of the equipment in Figure 1 ;

shows a side view of a roof bolter rig fitted with the apparatus of the invention;

shows a perspective view of the equipment in Figure 3;

shows a side view of a rock drill boom fitted with alternative apparatus of the invention; and

shows a side view of a rock drill boom fitted with a further alternative apparatus of the invention.

DETAILED DESCRIPTION OF THE INVENTION

Referring to the Figures 1 and 2, one embodiment of hanging wall support apparatus (1 ) in accordance with the invention is illustrated with reference to its use on a development end drill rig (not shown). The drill rig will be of the type having a forwardly disposed, movable beam (also not shown) with at least one pivotably mounted boom (2) for a rock drill (3).

The drill boom (2) in this example is of the telescopic type. In addition to having a carriage (or drill mounting) to advance the rock drill (3) along a deck of the boom (2) for rock penetration, the boom (2) itself is extendable with a front-end spike or stinger (4) for stinging a rock surface adjacent a position where a hole is to be drilled. Any alternative stinging formation(s) may also be used. The arrangement achieves a desired engagement of the rock surface that provides stability in use and facilitates collaring of a drill steel (3.1 ).

The development end drill rig will be used to drill blast-hole patterns in a face and also support holes for rock anchors into the sidewalls and hanging wall. In executing the latter, the boom (2) will be pivoted into a substantially vertical position, as shown in the drawings (or, at least into a position substantially normal to relevant part of the hanging wall). When it is used in this manner, the hanging wall support apparatus (1 ) and boom (2) provide a required degree of support of hanging wall, and the stinger (4) will not (usually) come into contact the rock face, as explained below.

The boom in this example is accordingly also an extendable prop (2) within the scope of the current invention's application, which is also further described below. The hanging wall support apparatus (1 ) of the invention consists of a frame (5) that is securable to the extendable prop (2) and, in the illustrated embodiments, provides an openwork screen structure (6) supported in front of a front or leading end (8)of the prop (2). The frame (5) includes four supports (7) of suitably rigid construction. The supports (7) extend from the prop (2) outwardly around the front end (8) that carries the spike (4) with the prop (2) occupying a substantially central position. In this embodiment, each of the supports (7) provides a spaced apart hanging wall engaging component (9), which form a hanging wall engaging structure (14) when the apparatus (1 ) is in use. The supports (7) are bent outwardly adjacent their free ends to provide a curved configuration where they form the engaging components (9). The openwork screen structure (6) includes an arrangement of suitably flexible connectors (10) spanned between the engaging components (9). The connectors (10) are provided by elements of wire rope and will preferably be formed as a wire rope net (1 1 ).

A substantially central opening (6.1 ) is provided through which the leading end (8) of the prop (2) engages the hanging wall. The opening (6.1 ) also provides for passage of the drill steel (3.1 ). In this embodiment the opening (6.1 ) is provided through a rigid ring (6.2) connected to the engaging components (9) by the wire rope net (1 1 ).

The supports (7) are provided in two pairs or sets (12) and (13) of two supports (7). The supports (7) in each set (12) and (13) are rigidly connected to each other at an end opposite to the free ends with engaging components (9). The separate sets of supports (12) and (13) are provided on opposite sides of the prop (2) and have a separate articulated or pivoting connection (15) which affords a required degree of pivoting.

The pivoting of the frame (5) about the articulated connections (15) will be limited by stops (not shown) that will allow adequate movement to accommodate an uneven hanging wall. The frame (5) will preferably be resiliently biased away from the stops for return into a central or neutral, preloaded position (as shown in the drawings) once it is disengaged from the hanging wall. The telescopic boom or prop (2) includes an extendable leg (16) for engagement with a footwall to resist downward force being applied to the cantilevered support beam of the development end drill rig from the telescopic boom (2) on engagement with the hanging wall. The leg (16) is hydraulically extendable in this embodiment but may simply be provided with a locking pin to secure the beam at the required height.

With the leg (16) engaged against the footwall, the telescopic boom (2) will be extended to contact the hanging wall. In this example, a force of approximately 1 ton will be provided by the telescopic action of the boom (2). Each of the supports (7) and leg (16) will have a combined 5 ton capacity.

The hanging wall engaging structure (14) of the frame (5) serves as a load spreader. The configuration provides an increased supported area on the hanging wall around the position of a drill hole that is provided for insertion of a roof bolt or other rock anchor.

The outwardly curved configuration of the engaging components (9) together with the articulation connection (15) facilitate desirable engagement and loading of the frame (5) when biased against an uneven surface of a hanging wall.

The hanging wall support apparatus (1 ) of this embodiment will be removably securable to the boom (2) and relatively lightweight for convenient changing. This will allow for easy removal between roof bolting operations when the apparatus (1 ) is not required. [It is also anticipated that the apparatus may be pivoted into an inoperative condition by having removable stops associated with the articulated connection (15).] With the hanging wall support apparatus (1 ) removed from its operative position, the stinger (4) will be brought back into operation for engagement against a rock face, as required for drilling blast holes to advance a development end (for example).

It will be appreciated that the configuration and features of the openwork screen structure (6) and frame (5) may be varied without departing from the scope of the invention. The number of supports (7) and/or engaging components (9) may be changed and the occurrence, position, spacing, density and/or number of connectors (10) between the components (9) may also be varied. The articulated connections (15) may embody a variety of constructions that afford the required movement of the frame (5) to accommodate an uneven hanging wall and distribute the support load of the prop (2).

The use of fixed (or removably securable) embodiments of the hanging wall support apparatus will also find specific application on portable roof bolting rigs. The apparatus may be used fitted to a boom or on one or more support props included on the rig.

Such apparatus (101 ) is shown in Figures 3 and 4 fitted to an extendable prop providing a telescopic stinging boom (102) of a roof bolter rig (103).

The hanging wall support apparatus (101 ) includes an openwork screen structure (104) with a frame (105) provided by a plurality of suitably rigid supports (106). The openwork screen structure (104) is secured to the extendable prop or boom (102) with the supports (106) extending outwardly. A fixed embodiment of the hanging wall support apparatus (101 ) is suited to this application where the openwork screen structure (104) is required for protection whenever the roof bolter rig (103) is in use.

In this embodiment, the openwork screen structure (104) once again provides part of a hanging wall engaging structure (107) that is secured to the prop for engagement with a hanging wall.

The supports (106) extend upwardly from a position at (108) spaced apart from a leading end (109) and approximately in the middle of the extendable prop (102). More specifically, the frame (105) is provided by four supports (106) arranged as two pairs of supports (106) respectively secured to opposite sides of the extendable prop (102). The prop (102) is accordingly located in the arrangement at a substantially central position relative to the openwork screen structure (104). As with the first embodiment, shown in Figures 1 and 2, the supports (106) provide spaced apart rock engaging components (1 10) of the hanging wall engaging structure (107).

The openwork screen structure (104) includes a plurality of connectors (1 1 1 ) secured between the supports (106). The connectors (1 1 1 ) are flexible and are arranged as a net (1 12). In this example, the connectors (1 1 1 ) are provided by webbing (instead of wire rope).

The supports (106) of the openwork screen structure (104) are movably connected to the extendable prop (102) through at least one articulated connection (1 13) that affords limited pivoting. More specifically, each support (106) includes a joint (1 13) through which it is pivotably secured to the prop (102). Each joint (1 13) is fitted with a rigid spring (1 14) extending over the joint to (1 13). The springs (1 14) provide a resilient bias that serve to return the supports (106) to a pre-loaded position, when they are not biased against a hanging wall. The openwork screen structure (104) is arranged with an access opening (1 15) shown in Figure 4 that is positioned for passage of a drill steel (not shown) and installation of a rock bolt.

The operation and engagement of the openwork screen structure (104) against a hanging wall for drilling and roof-bolting operations is substantially the same as for the first embodiment.

The changes shown in the components of the apparatus (101 ) of Figures 3 and 4 over those features of the embodiment in Figures 1 and 2 could equally be implemented where the equipment and apparatus of the invention is to be used on a development end drill rig. The invention accordingly provides hanging wall support apparatus (1 ) which can take a variety of forms and is capable of application on any of a wide variety of props or other extendable hanging wall support units. In one such variation in the application of this load spreading equipment, the hanging wall support apparatus will be fitted to a mechanically extendable prop of the kind known under the brand "CAMLOK" and commonly used in the South African mines (or some other support prop that is manually extendable through a suitable mechanism). In this manner, additional supported area will be achieved by a single prop that is manually installed.

Where a telescopic support prop (not providing a drill feed) on a roof bolting rig has a smooth piston component with a pointed end, the apparatus may involve use of an inverted sheath or cap that sits over and/or around the pointed end and to which a frame of an openwork screen structure is secured.

In other variations of the invention, an openwork screen structure (199) may be provided at a position (on the extendable prop) where it will in use be supported at a position spaced apart from the hanging wall. Examples of such embodiments are shown in Figures 5 and 6. These are illustrated as modifications to the equipment in Figure 1 . The extendable prop (2) is provided with a central stinger (200) that provides a hanging wall engaging formation (200). In Figure 5, a steel cable (201 ) will be tensioned between the upper, free ends of the four arms (7) and a lower anchor point (202) on the extendable prop (2). The steel cable (201 ) will in the case of this modification serve to keep the connectors (10) of the wire rope net (1 1 ) spread. Alternatively, as shown in Figure 6, a rigid steel beam (203) is secured between the stinger (200) and the upper, free ends of each of the four arms (7), respectively. The four steel beams (203) serve to keep the connectors (10) of the wire rope net (1 1 ) spread and under tension. The four arms (7) of the openwork screen structure (199) in both Figures 5 and 6 may also be rigidly connected at (215) to the prop (2). This arrangement will be more viable where an irregular hanging wall is less likely to be engaged by the openwork screen structure (199) in use. A larger space or gap between the openwork screen structure (199) and the end of the stinger (200) would make such contact less likely.

It will be appreciated from the specific description of the invention that the term "openwork screen structure" includes: a combination of parts or components or members that are secured in relation to each other to define openings, gaps or spaces therebetween; and/or

a net; and/or

a grid; that prevents to a suitable and/or required degree the passage of rocks that work loose from a hanging wall to provide a screen or barrier.

The openwork screen structure may accordingly, alternatively be provided by a grid of rigid components or by a suitable metal plate with openings formed therethrough in the manner of a grid.

A person skilled in the art will also appreciate that a number of additional variations may be made to the features referred to without departing from the scope of the current invention.

Variations in the configuration of the openwork screen structure, which either does or does not form part of a hanging wall engaging structure, will be within the design competence of a person suitably skilled in the art.