FIELD OF THE INVENTION

[0001] The invention relates to a mine safety net and, more particularly, to a mine safety net which has improved tensile strength.

BACKGROUND OF THE INVENTION

[0002] A safety net is used in a mine excavation to arrest rock falling from a wall of the excavation.

[0003] A typical safety net of the applicant is comprised of a quadrilateral mesh body with a perimeter comprised of a pair of longitudinal members and a pair of transverse members, a first plurality of elongate tensile elements extending between the pair of longitudinal members, in a first direction, and a second plurality of elongate tensile elements extending between the pair of transverse members, in a second direction.

[0004] The elements and members are straps of a woven polymeric material. [0005] Typically, the elements of the first and the second plurality engage the members of the perimeter by overlap. Within the zone of overlap, the elements are attached to the members by stitching. Furthermore, at each corner of the perimeter, a transverse member engages a longitudinal member by overlap. Within the zone of overlap, the respective members, again, are attached by stitching. [0006] A safety net such as this has to arrest rocks from a rock fall without breaking. To do this, the net has to absorb the energy of the falling rock. The elements and members do this by stretching. Due to the material of composition and the woven pattern, the elements and members have high tensile strength i.e. a high capacity to stretch before breaking.

[0007] The inherent limitation to the energy absorbing capacity of such a safety net lies in the attachment zones. It has been observed that the safety nets is prone to snap and fail within or adjacent these attachment zones.

[0008] The current invention at least partially solves the aforementioned problem.

SUMMARY OF INVENTION

[0009] The invention provides a knotless woven steel rope safety net which includes a frame comprised of an integral length of a first rope formed into a quadrilateral shape and held in the shape by joining ends of the rope together thereby to define a pair of longitudinal sides and a pair of transverse sides, and a mesh within the frame comprised of an integral length of a second rope and an integral length of a third rope, wherein each of the second and third ropes provide a plurality of mesh sections, each mesh section extending between a respective longitudinal side and a respective transverse side of the frame in an oblique direction relatively to the side of the frame, wherein the mesh sections engage with one another at crossover points, and wherein each of which engages with the frame and to engage with one another; and wherein at each end of a mesh section, the respective second rope or third rope engages the respective side of the frame by looping under and over the first rope. [0010] The net may include an integral length of a fourth rope which is interconnected with the first rope, in reinforcement, and formed into a quadrilateral shape to provide the frame.

[0011] The fourth rope may be attached to the first rope at a plurality of spaced locations and at each location attachment may be provided by a fastener such as a clip or a wire C ring.

[0012] The ropes may be coated with PVC or the like.

[0013] As an alternative, the frame may be reinforced by causing the first rope to follow the shape of the frame through a plurality of windings and wherein on the last winding one end of the rope is attached to an opposed end of the rope.

[0014] At each corner of the frame, the net may be adapted to provide a means for hook or support attachment. The means may be each corner which is wrapped with a reinforcing fabric. Alternatively, the means may be a loop provided by a respective end section of the second and third rope. [0015] At the crossover points, the respective mesh sections may be attached with a fastener. Preferably, at each point of intersection, the respective mesh sections are attached together with a pair of wire fasteners, one of which is engaged in a longitudinal direction, the other in a transverse direction.

[0016] From another perspective, the invention provides a knotless woven steel rope safety net which includes a frame comprised of an integral length of, at least, a first rope formed into a quadrilateral shape and held in shape by joining ends of the rope together thereby to define a pair of longitudinal sides and a pair of transverse sides; a mesh within the frame comprised of integral lengths of, at least, a second and a third rope; wherein, in providing the mesh, the second and the third ropes are woven to extend between a respective longitudinal side and a respective transverse side in oblique directions and to engage with one another at points of intersection; and wherein, the second and the third ropes attach to the respective side of the frame by looping under and over the first rope.

[0017] To reinforce the frame, the frame may include an integral length of a fourth rope which is attached to the first rope before forming into a quadrilateral shape.

[0018] The first and the fourth rope may be attached at intervals with a wire fastener such as a clip, a ring or the like.

[0019] Alternatively, to reinforce the frame, the first rope may loop about the shape in a plurality of passes until, on a last pass, ends of the first rope are connected together.

[0020] At each corner, the frame may be wrapped with a canvas material or the like to reinforce and to rigidity the frame at the corners.

[0021] The second and third ropes may be attached, at the points of intersection, with a fastener such as a wire clip, ring or the like. [0022] The second and the third rope may terminate adjacent a respective corner, by attachment of the respective end of the rope to a section the third rope or the second rope respectively.

[0023] Alternatively, within each corner of the frame, respective end sections of the second and third rope may be formed in a loop, each to provide a hook attachment formation.

BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The invention is described with reference to the following photographs or illustrations in which: Figure 1 is a view in perspective of a knotless woven steel rope safety net in accordance with a first embodiment of the invention;

Figure 2 is a view of a corner of the safety net of Figure 1 ;

Figures 3, 4 and 4A are diagrammatic representations of a frame of the safety net in construction; Figure 5 is a diagrammatic representation of a knotless woven steel rope safety net in accordance with a second embodiment of the invention;

Figure 6 is a diagrammatic representation of a corner of the knotless woven steel rope safety net in accordance with a second embodiment of the invention

Figure 7 is a diagrammatic representation of the net in installation; Figures 8 and 8A is a diagrammatic representation of a knotless woven steel rope composite safety net in accordance with a third embodiment of the invention; and

Figures 9 and 10 is a diagrammatic representation of a knotless woven steel rope composite safety net in accordance with a fourth embodiment of the invention. DESCRIPTION OF PREFERRED EMBODIMENT

[0025] Figure 1 illustrates a safety net 10A, in accordance with a first embodiment of the invention. The safety net 10 includes a quadrilateral frame 12 and a mesh 14 within the frame. The mesh is a diamond-shaped mesh.

[0026] The frame 12 is defined by a pair of longitudinal sides (respectively designated 16A and 16B) and a pair of transverse sides (respectively designated

18A and 18B). Between a respective longitudinal side and a transverse side, one of four corners (respectively designated 20A, 20B, 20C and 20D) is defined.

[0027] The frame 12 is comprised of a pair of high-tensile resiliently deformable steel ropes, respectively designated 22A and 22B (see Figure 2). Each rope of the pair is co-extensive, and interconnected, with the other. The interconnected pair cooperatively increases the tensile strength of the frame. Interconnection is achieved with a plurality C-shaped wire clips 25, each of which is crimped onto the pair. Each rope is of an integral length so as not to introduce unnecessary points of connection which will introduce weakness to the frame. [0028] The frame 12 is bent to conform, substantially, to a quadrilateral shape. To hold the frame in shape, respective end sections (not shown for this embodiment) of each frame rope (22A and 22B) are interconnected. A heavy duty fabric material such as canvas material or the like can be wrapped about each corner 20 as a reinforcing wrapping 23. The wrapping rigidities the corner, aiding in the maintenance of the quadrilateral shape. Alternatively, a plurality of wire C rings can be attached to each corner to achieve this rigidity. [0029] The mesh 14 is made up of a first mesh rope 24 and a second mesh rope

26. The first mesh rope has ends 28A and 28B. The second mesh rope has ends 30A and 30B. Again, both of these ropes are integral-length ropes of substantially equal length.

[0030] By weaving or interlacing both these ropes (24, 26) between a respective longitudinal side 16 and a transverse side 18 of the frame 12, in diagonal or oblique directions, and looping the rope over and under the respective side when the rope meets the frame, the crossover of a plurality of rope sections 24A, 24B, 24C...24N (from rope 24) and 26A, 26B, 26C...26N (from rope 26), make up the mesh.

[0031] More specifically, taking rope 24 by way of example, from end 28A, located adjacent corner 20A, the rope extends to longitudinal side 16B in a first oblique direction (see rope section designated 24.1). At side 16B, the rope is looped under and then over the frame before extending to transverse side 18B (see section designated 24.2) in a second oblique direction which is substantially perpendicular to the first oblique direction. Again, on meeting the frame, the rope is looped under and then over the side before extending in the first oblique direction towards longitudinal side 16A (see section designated 24.3). This weaving pattern continues until the rope 24 terminates adjacent corner 20B at end 28B. [0032] Rope 26 is woven within the frame following the same pattern described. At crossover points 32 at which the ropes (24, 26) intersect, the ropes are attached together with a clip 25 (this is illustrated in Figure 2) or the like. This prevents mesh aperture shape distortion if the net is subjected to load due to rock fall, a problem which could allow rock fall from penetrating the net through a deformed mesh aperture.

[0033] At each corner 20, the respective end (28A, 28B, 30A, 30B) of each rope (24, 26) is fixed by attachment to a perpendicular extension of the other rope 26. By way of example, as illustrated in Figure 2, at corner 20C the end 30A of rope 26 is looped around rope section 24.2. The overlapped sections of the rope 26 is crimped together with a clip 25.

[0034] Figures 3 to 6 illustrate a safety net 10B, in accordance with a second embodiment of the invention. In describing this embodiment, and all subsequent embodiments, like features bear like designations. [0035] This embodiment 10B differs from the preceding embodiment (10A) in the configuration of the frame 12 and the mesh 14.

[0036] Net 10B has a frame 12 which is comprised of an integral steel rope 22. To constitute the frame, the rope 22 is resiliently wound about a quadrilateral shape through a plurality of passes. The number of passes preferably is three and this is illustrated in Figure 3. By employing this technique, the frame is strengthened without increasing the number of connections points present in the frame. This net only has an integral connection point 40 (see Figure 4A). The bundle of parallel sections of the rope 22, making up the frame, is held together with clips 25. [0037] At the attachment point 40, rope end section 42 is formed into a first loop 46, with the loop being maintained with a clip 25 (or clips), before an opposed end 44 is passed through the first loop and looped back on itself to form a second loop 48 which again is maintained by a clip or clips. This attachment configuration makes it difficult for the end sections to pull apart, even under high levels of load, and for then frame 12 to then unravel.

[0038] The mesh 14 of this net 10B, like with the net 10A, is comprised of a first and a second mesh rope (24, 26). These ropes are woven or intertwined between respective sides (16, 18) of the frame 12 in the same manner as described above with respect to net 10A. However, where the mesh of net 10B differs from the mesh of net 10A is in the configuration of ends (28A, 28B, 30A and 30B) of each rope (24, 26).

[0039] Ends (28A, 28B, 30A and 30B) do not end blindly in attachment to a perpendicular extension of the other rope (rope 24 or 26 as the case may be) as with net 10A. With reference to Figure 6 which, by way of example, illustrates corner 20A, an end length of the rope section 24.1 is formed into a loop 50 which is positioned between rope section 26.2 and an inside of corner 20A. The loop is held open by attachment to adjacent legs of the frame corner with clips 25. To maintain the integrity of the loop 50, the end 28A is looped around rope section 26.2 in overlap. The overlapping sections are clasped together by means of a C clip (or clips) 25. In Figure 6, this clip is illustrated in an open configuration prior to being crimped. [0040] The loops 50 at each corner 20 provide a reinforced formation through which an attachment element, such as an S hook 64, is received in use of the net 10B as will be described below.

[0041] A plurality of nets (10A or 10B) often are required to be conjoined to extend along a blast face 54 beneath the adjacent hanging wall 52 (see Figure 7). The nets can be conjoined in situ after being consecutively installed adjacent one another in the dip direction (designated X on Figure 7). Alternatively, a composite net 10C can be manufactured for use in an integral - rather than multiple - installation step.

[0042] With reference to Figure 8 (wherein the loops 50 are omitted for ease of illustration), the composite net 10C of the invention includes a first panel 10.1 and a second panel 10.2. The number of panels is not limiting on the invention and it is envisaged that more than two panels may make up the composite net, with the number of panels dictated by requirement.

[0043] Each panel is, in most respects, identical to the net 10B in its configuration. Flowever, the panels are not merely connected with a joining strap or the like as would be the case with a conjoined in situ example. The transverse sides 18.1 B and 18.2A, of the frames 12 of panels 10.1 and 10.2 respectively, in this example, combine to form a common perimeter 56. On meeting the common perimeter from respective sides, the mesh ropes (24, 26), of each adjacent panel, loop under and then over the perimeter in continuous unbroken attachment for intimate conjugation of the panels (10.1 , 10.2). This is illustrated in Figure 8A. [0044] Figures 9 and 10 illustrate another embodiment 10D of the invention. The only difference between the net 10D and the net 10B is in the making and configuration of the frame 12.

[0045] The frame 12 of net 10D, like net 10B, is constituted of an integral steel rope 22 which is wound about the quadrilateral shape through a plurality of passes. The difference however is that on the third pass, approximately 2/3 of the way along a transverse side 18, the rope makes a premature longitudinal pass across the net to provide an integral rope boundary section 58. The boundary section divides the net into a first partition 60 and a second partition 62. The benefit of this configuration will be described below.

[0046] With reference to Figure 7, in use of the safety nets 10A, 10B or 10C, an attachment element, for example an S-hook 64, is attached to each corner 20 of the net. The point of attachment is reinforced by the wrapping 23 seen on net 10A, or the provision of loops 50 seen on nets 10B and 10C. These hooks then are attached, firstly, to temporary support units 66, and then to pre-installed support 68 in or on the hanging wall 52 of the mine excavation. The safety net thus is suspended below the hanging wall, adjacent the blast face 54. In this position, the net will arrest rock fall from the hanging wall to prevent harm to a mine worker beneath.

[0047] Net 10D offers an option if an industry convention 0.8, 1.0, 1.2 or 1.5 meter advance in the strike distance (designated Y on Figure 7) is not achieved in a particular day. The other net embodiments which are nets of a standard dimension (1.2 meters in the strike, or transverse, direction) would not be fully extensible in the strike direction, necessitating the need to attach the net along an intermediate longitudinal line. With no reinforcement, attachment along this line will load limiting.

[0048] With net 10D providing a reinforced intermediate line for attachment, approximately 80cms along the transverse sides 18 of the net, with the integral rope boundary section 58, reinforcement to attachment is provided. The first partition 60 of the net is thereby fully extended below the hanging wall, with the partition 62 hanging loosely, to be attached as the excavation advances in the next shift.

[0049] All the embodiments (10A, 10B, 10C and 10D) of the invention have no attachment points or knots between the mesh 14 and the frame, due to singular lengths of ropes used and the manner in which the net is constructed. Thus, points of weakness have been removed making for a stronger net, less likely to break and fail when placed under load when compared to its prior art counterparts.

[0050] Furthermore, the shape, configuration and material of manufacture of these nets are complementary features in providing a net with low deformation properties, capable of distributing the kinetic energy of rock fall evenly through the mesh and about the frame.