SCAFFOLDING SAFETY MESH
[0001] The present invention relates to safety equipment for the building industry and, more particularly to building perimeter containment screening.
BACKGROUND
[0002] It is common practice and/ in some jurisdictions at least, a requirement that scaffolding, particularly in high rise building construction, include a safety mesh material affixed at the inside or outside face of the scaffolding.
[0003] Traditionally such meshee have been comprised of woven steel wire, such as chain wire, or of welded steel mesh, such as "Brick Guard". Both these materials are heavy to lift and awkward to install, with the weight additionally a safety hazard should the material be dropped before it is properly secured. Such heavy steel wire meshes also add an undesirable dead load to the scaffold.
[0004] In recent times a lighter weight material has become used in the industry. It comprises a sheet of shade cloth or similar material, reinforced by a grid of webbing straps . These webbing straps are formed by co-extruding a polymer envelope around a plurality of side by side wires.
[0005] Although significantly lighter than chain wire or welded mesh, the multiple strands of wire embedded in the straps still represent a weight penalty. Moreover, the production of this specialised strap material is expensive, requiring close production control and specialised equipment .
[0006] Thus the purpose of the present invention is to provide a new polymer strap grid backed safety mesh to solve the unsafe problem of the current mash with its poor anti-bursting and anti-impact ability, to achieve the goal of a long life span, and high reliability for safety protection on construction sites.
[0007] The present invention provides a polymer strap grid backed safety mesh. It is constructed as a polymer strap grid with a layer of woven or knitted mesh or fabric. The embodiments of the present invention are comprised of spaced apart high strength polymer straps to form
horizontal elements and vertical elements. In at least some preferred embodiments , the woven or knitted fabric sheet is fixed to one side of the said 9trap grid.
[0008] The polymer grid backed mesh of the present invention is characterised by light weight, high tensile strength, high flexibility, due to the combination of the grid and woven or knitted fabric. It greatly improves the anti-impact ability, and effectively increases anti- bursting ability, as well as increasing the life span of the product and therefore increasing the reliability of protection on sites.
Notes
[0009] The term "comprising" (and grammatical variations thereof) is used in this specification in the inclusive sense of ^having" or "including", and not in the exclusive sense of ^consisting only of".
[0010] The above discussion of the prior art in the Background of the invention, is not an admission that any information discussed therein is citable prior art or part
of the common general knowledge of persons skilled in the art in any country.
BRIEF DESCRIPTION OF INVENTION
[0011] Accordingly, in a first broad form of the invention, there is provided a scaffolding safety mesh for use with a scaffolding assembly; said safety mesh formed exclusively of homogenous polymer materials; said safety mesh including at least a first- series of parallel longitudinal polymer straps (as herein defined) and a second series of parallel polymer straps transverse to said first series; straps of said first series and straps of said second series joined together at least at a proportion of intersections of said straps.
[0012] Preferably, said first series of polyme straps and said second series of polymer straps are woven into a grid of said polymer straps; each strap of said first series alternately lying at a first side of a strap of said second series and at an opposite second side of said strap of said second series, at the intersections of said straps.
[0013] Preferably, said straps of said first series of polymer straps form a first layer; said polymer straps of said second series forming a second layer; polymer straps of said second layer overlying said straps of said first layer to form a two layer grid of said polymer straps.
[0014] Preferably, alternate intersections of said grid of polymer straps are fused together by application under heat and pressure of polymer patches; said polymer patches of a size to cover at least an area of overlap of said straps at said intersections.
[0015] In another broad form of the invention, there is provided a scaffolding safety mesh for use with a scaffolding assembly; said safety mesh formed exclusively of homogenous polymer materials; said safety mesh including at least a first series of parallel longitudinal polymer elements and a second series of parallel polymer elements transverse to said first series; elements of said first series and elements of said second series joined together at least at a proportion of intersections of said elements; said mesh further including a sheet of woven or knitted polymer cloth assembled to said polymer straps at said proportion of intersections of said elements.
[0016] In another broad form of the invention, there is provided a scaffolding safety mesh attachable to outer elements of a scaffold assembly; said safety mesh comprising first, second and third polymer layers; said first and second polymer layers forming a supporting grid comprising arrays of spaced-apart parallel vertical and horizontal polymer straps respectively; said third layer comprising a fine woven or knitted polymer fabric attached to one side of said supporting grid.
[0017] Preferably, said vertical and horizontal polymer straps comprise a co-extruded polymer with embedded strands of wire.
[0018] Preferably, said vertical straps comprise a co- extruded polymer with embedded strands of wire; said horizontal straps extruded as homogenous polymer straps; said first and second layers forming a grid of asymmetric stiffness.
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[0019] Preferably, said straps measure between 10mm and 15mm in width and between 1 and 2mm in thickness.
[0020] Preferably, spacing between said vertical straps is less than spacing between said horizontal straps; said differential spacing between said vertical straps and said horizontal straps forming a grid of asymmetric stiffness.
[0021] In another broad form of the invention, there is provided a method of forming a scaffolding safety mesh; said method including the steps of:
a) extruding polymer material into straps for elements of first and second layers of a supporting grid of said safety mesh,
b) co-extruding said polymer material with strands of wire to form straps with embedded wires for at least vertical elements of said supporting grid, c) arranging lengths of said horizontal elements to form an array of equally spaced- part straps forming said first layer of said grid,
d) arranging lengths of said vertical elements to form an array or equall spaced-apart straps transverse to said horizontal elements forming said second layer of said grid.
e) overlaying a third layer comprising a fine woven or knitted polymer fabric over said first and second layers and applying an adhesive or heat- welding to assemble said fine woven or knitted polymer fabric to. one side of said first supporting grid to form said scaffolding safety mesh .
[0022] I another broad form of the invention, there is provided a polymer grid safety protection mesh, comprising
a strap grid, and woven or knitted fabric, for use on an outer side of scaffolding; said strap grid formed of high strength polymer material, comprising spaced apart horizontal straps and spaced apart vertical straps; said woven or knitted fabric being attached on one side of said strap grid.
[0023] Preferably, said grid and woven or knitted fabric are made of a polymer material; said polymer material including polyethylene (PE) , and polyethylene terephthalate (PET) .
[0024] Preferably, said horizontal straps and vertical straps may comprise grid sheet formed in one integrated manufacturing process.
(0025] Preferably, the said horizontal straps and vertical straps are made of high strength polymer material, and may be formed elongate, and flat shape through the process of injection, or/and stretching, or/and weaving and knitting.
[0026] In another broad form of the invention, there is provided a polymer grid and fabric safety mesh for attachment at the outer perimeter of scaffolding; said grid comprising spaced apart horizontal and vertical straps; said straps formed of side by side woven bundles of polymer strands; said horizontal and vertical straps at least partially heat fused and sewn together at their cross over points; said fabric comprising a polymer woven or knitted cloth attached to one side of said grid.
[0027] Preferably, said safety mesh includes a supporting grid of said horizontal and vertical straps with
said woven or knitted fabric attached to one side of said grid; aaid safety mesh further including a panel extending along a lower edge of a sheet of said mesh; said panel formed of a sheet of polymer so as to form a toe board along a scaffold platform.
[0028] Preferably, said sheet of polymer is formed with transverse corrugations spaced at intervals along the length of said sheet to facilitate rolling up the safety mesh for both storage and on-site handling.
[0029] Preferably, apertures are provided at intervals along a lower edge 508 of sheet of polymer; said apertures coinciding with openings in said grid of said mesh so as to allow for the passage of cable ties or clips to secure said mesh to an adjacent scaffold rail.
BRIEF DESCRIPTION OF DRAWINGS
[0030] Embodiments of the present invention will now be described with reference to the accompanying drawings wherein;
Figure 1 is a front view of a portion of a sheet of safety mesh according to a first preferred embodiment of the invention.
Figure 2 is a f ont vie of a portion of a sheet of scaffolding safety mesh according to a second preferred embodiment of the invention, .
Figure 3 is a front view of a portion of a sheet of scaffolding safety mesh according to a third preferred embodiment of the invention,
Figure 4 is a front view of a portion of a sheet of scaffolding safety mesh according to a fourth preferred embodiment of the invention,
Figure 5 is a front view of a portion of a sheet of scaffolding safety mesh according to a fifth preferred embodiment of the invention,
Figure 6 is a sectioned end view showing any one of the embodiments of the scaffolding safety meshes of Figures 1 to 5 mounted to a perimeter frame,
Figure 7 is a front view of the mesh of Figure 4 provided with a toe board.
Figure 8 is a first preferred arrangement of a polymer strap grid for the safety mesh according to the invention,
Figure 9 is a sectioned view of the polymer strap grid of Figure 8,
Figure 10 is a preferred embodiment of a safety mesh according to the invention in which the polymer strap grid of Figures 8 and 9 have been combined with a woven or knitted polymer fabric.
Figure 11 is a front view of a further preferred embodiment of the invention;
Figure' 12 is a front view of a another preferred embodiment;
Figure 13 is a front view of another preferred embodiment ;
Figure 14 is a rear view of the preferred embodiment of figure 11;
Figure 15 is a sectioned view A-A of the preferred embodiment of figures 13 and 1 .
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0031] Each of the first five preferred embodiments of the scaffolding safety mesh of the present invention, is characterized in that the mesh Is a wholly homogeneous construct of polymer materials. That is, there are no non- polymer components included in the mesh. Each of the embodiments of the mesh utilises as the primary
constituents, longitudinal and transverse elements or straps of a polymer material, which may be extruded or cut from polymer sheet. [0032] The term straps used in this specification refers to longitudinal and transverse elements which are relatively broad compared to their thickness. The ratio of width to thickness is at least in the order of ten to one, with the thickness being less than 2mm. A preferred configuration of the strap is 1mm thick by 12mm width.
First Preferred Embodiment
[0033] With reference to Figure 1, in a first embodiment the scaffolding safety mesh 10 is formed of a first series of parallel longitudinal polymer straps 12 and a second series of parallel transverse polymer straps 14. In this instance the first series of longitudinal straps 12 and the second series of transverse straps 14 are interwoven so that each strap of first series alternately lies at a first side of a strap of the second series and at an opposite second side of the strap of the second series where the straps intersect 16.
[0034] At least a proportion of the intersections 16 of the straps of the first series and the second series are joined together. Preferably alternate intersections along a given strap are so joined, with alternate intersections along the next parallel adjoining strap also joined but staggered relative the first strap as shown in Figure 1 (indicated by ^X") . The joining of straps 12 and 14 at the intersections 16 may be effected by various means, for example by heat welding, riveting as indicated in Figure 2, or with a suitable adhesive.
Second Preferred Embodiment
[0035] In a second preferred embodiment of a scaffolding safety mesh 100 shown in Figure 2, the straps 112 and 114 making up the grid of the mesh, are not interwoven but form two layers, made up of a first array of parallel longitudinal straps 112 overlaid by a second layer of parallel transverse straps 114. Again these are interconnected at least in a regular pattern, either at staggered alternate intersections as described above, or at every intersection.
[0036] In both the above described embodiments, a typical spacing of the grid forming the mesh is at 40mm by 40mm. However it will be understood that a denser grid of straps can be employed to increase impact and penetration characteristics .
Third Preferred Embodiment
[0037] Figure 3 shows a preferred method by which the longitudinal and transverse straps 212 and 214 making up the grid of the scaffolding safety mesh 200 of the invention may be connected at selected intersections 216. In this embodiment, patches 218 of the same polymer material as that of the straps 212 and 21 , are applied under heat and pressure at the selected intersections 216. Preferably, application is by means of a dispensing gun (not shown) which provides both heat and pressure to fuse the patch and the two intersecting straps together. Fourth Preferred Embodiment
[0038] In a further embodiment of a scaffolding safety mesh 300 according to the invention, the arrangement of Figure 2, in which the longitudinal and transverse straps are not woven but form two distinct layers, a finer polymer
woven or knitted meah 220, such as a shade cloth, may be interposed between the two layers as shown in Figure 4. Again, in this embodiment also, selected intersections may be interconnected by any of the above mentioned fastening methods. Thus the two layers and the sheet of woven or knitted polymer mesh 320 may be fused together by heat welding, riveting, the application of patches or by an adhesive. Fifth Preferred Embodiment
[0039] In still another preferred embodiment of the scaffolding safety mesh 400 shown in Figure 5, a grid of longitudinal and transverse polymer straps 412 and 414 is formed, either woven as described for the first embodiment above, or as two discrete layers as for the second embodiment. In this case however, a sheet of fine woven or knitted polymer mesh 420, such as shade cloth, is applied to one side of the grid and the three layers, of straps and woven or knitted mesh fastened together by any of the methods already described, but more preferably by patches 418.
[0040] In any of the above described embodiments, the safety mesh of the invention ma include a polymer sheet section 502 along a lower edge of the mesh, acting as a ""toe board" as shown in Figure 7. As defined by Australian Standards, a toe board may comprise a vscaffold plank or purpose designed component fixed on the edge of a pie tform/ to prevent material falling from the platfoxm." In the safety mesh of the present invention, the "purpose designed component" is preferably an elongate strap of polymer sheet 502, some 200mm wide fixed to the longitudinal and transverse straps (514 and 512) of the mesh.
[0041] Again preferably, the toe board sheet of polymer 502 is formed with transverse corrugations 504 spaced at intervals along the length of the sheet to facilitate rolling up the safety mesh for both storage and on-site handling. Preferably, apertures 506 are provided at intervals along the lower edge 508 of the toe board sheet 502, coinciding with openings in the grid of the mesh, to allow for the passage of cable ties or clips to secure the mesh to an adjacent scaffold rail.
[0042] With reference now firstly to Figure 10, a scaffolding safety mesh 610 according to a further preferred embodiments of the invention, is comprised of three layers of a polymer material to form a sheet of safety mesh. The three layers may, though need no necessarily, be formed of the same polymer.
Sixth Preferred Embodiment
[0043] As shown in Figure 8, the first layer 612 of this first embodiment, is comprised of spaced-apart, parallel array of horizontal elements 614 extending the length of the sheet (only a portion of which is shown in Figure 8) .
These horizontal elements 614 are formed as homogenous, unreinforced, polymer straps, extruded from a suitable polymer material, such as polypropylene, polyethylene, polystyrene or polyester for example, by an extrusion process well understood in the art.
[0044] The second layer 616 is formed of an array of spaced-apart vertical elements 618, which are also formed of the same or compatible extruded polymer, but in this instance, are co-extruded with a number, preferably three or four strands of wire 620 embedded within the polymer matrix as shown in the section view of Figure 9.
[0045] In each case the strap elements 614 and 618 of the first and second layers 612 and 616 are relatively broad compared with their thickness. Preferably the ratio of width to thickness is least in the order of ten to one, with the thickness being less than 2mm. A preferred configuration of the straps of the first and layers is 1mm thick by 12mm in width.
[0046] The third layer 622 of the present mesh (shown in Figure 10) is comprised of a standard, coarse woven or knitted polymer fabric 622, such as for example a shade cloth material. The first and second layers 612 and 616 of the mesh 610 form a reinforcing grid as shown in Figure 8. [0047] The scaffolding mesh of the embodiment of the invention shown in Figures 8 to 10, is preferably manufactured in elongate sheets, either in lengths of 7.5 or 15m by 2m in height so as to suit coverage of two or three bays of a scaffolding assembly respectively.
[0048] Preferably the vertical and horizontal spacings are equal so as to from square grids of the extruded polymer straps. The voids, that is, the openings defined by adjacent vertical and horizontal straps, are preferably 40mm by 40mm.
[0049] Typically, in manufacture, the homogenous elongate straps 614 forming the horizontal elements of the grid, will be laid down first on an assembly platform, possibly fed directly from an extruder (not shown). These elements 614 will then be overlaid by the wire reinforced vertical elements 618 to complete the grid. Adhesive and/or heat welding may be applied at this stage a the intersections of the horizontal and vertical elements.
[0050] Alternatively/ the sheet of woven or knitted polymer fabric 622 is first laid over the grid and the adhesive and/or heat welding applied to the three layers. [0051] It will be understood that the scaffolding mesh of this first embodiment of the present invention has an asymmetric stiffness. It is very flexible along the length of a sheet of the sheet so that the sheet may readily be rolled up along its length. However, the wire reinforcing of the vertical elements 618 provides considerable stiffness in the vertical direction.
[0052] This asymmetry of stiffness is of considerable benefit when a sheet of the mesh, initially in a rolled up condition, needs to be assembled to the outer perimeter of a scaffolding assembly. The mesh, after attaching the outer end of a rolled sheet to a scaffolding upright, can be unrolled in a relatively controlled manner with the vertical elements of the grid of the mesh assisting in the placement of the sheet along the bays of the scaffolding.
[0053] In an alternative arrangement, an asymmetry of stiffness may be provided in any of the embodiments of the mesh of the invention, without the reinforcing of one of the layers of parallel straps. An effective differential stiffness may be achieved by a differential spacing interval between the horizontal and vertical straps. Thus a relatively closer spacing of the vertical straps compared with the spacing of the horizontal straps will produce a sheet of mesh with similar advantageous properties as those of the reinforced vertical strap arrangement described in the Sixth Embodiment above.
Seventh Preferred Embodiment
[0054] In this seventh preferred embodiment, the safety mesh is again formed of three layers and is similar in all respects to the sixth embodiment above. However, in this arrangement, both the. horizontal and the vertical strap elements of the supporting grid are formed with strands of reinforcing wire 620 embedded in the extruded polymer matrix. As before, the woven or knitted polymer fabric is attached to one side of the supporting grid.
[0055] The advantages of this embodiment include the safety mesh acting as a semi-rigid, though light-weight panel, which, when sized as described above, may be quickly applied to the bays of a scaffolding structure.
[0056] The particular features common to both of the embodiments is that of relative ease of manufacture and the ability to readily replace damaged and worn out woven or knitted fabric. These features of the mesh of the present invention make significant contributio to the economics of providing safety meeh on scaffolding, as well as the convenience provided in either the rollable or panel forms of the mesh. Further Preferred Embodiments
[0057] As shown in the Figures 11 to 15, the safety mesh according to further preferred embodiments the invention, is again comprised of a polymer strap grid and woven or knitted fabric. The strap grid is made of high strength polymer material and is comprised of horizontal Straps
(711) and vertical Straps 712, which are spaced apart. The woven or knitted fabric 713 is fixed on one side of the strap grid. The high strength material may include
polyethylene (PE) , and polyethylene terephthalate [PET) .
[0058] It may also be made of other suitable high strength polymer material with similar strength criteria and similar function of usage. The horizontal straps (711) and vertical straps 712 are made of the above mentioned material, and are formed as either flat solid straps or flat fabric straps, through the processes of extrusion, or stretching, or weaving, or knitting, or stitching.
[0059] In one preferred arrangement, the straps 711 and 712 of the grid are formed of side by side flattened bundles of multiple woven polymer strands. Preferably the straps are formed of at least three, preferably four such bundles. The bundles of the horizontal straps and vertical straps may be at least partially heat fused or welded and/or sewn together at their cross over points and further linked at these cross over points by a sewing process. In a further or simultaneous process, heat may be applied to the assembled strap grid to cause at least partial fusion as well between the strands of the bundles and between the bundles themselves.
[0060] The formation of the strap grid may have various patterns. It may be formed, as shown in Figure 11, via weaving of the horizontal straps 711 and vertical straps 712, and applying adhesive or heat welding at the cross over points. It may also be formed, as shown in Figure 12, through the process of the sheet consisting of the
horizontal straps 712, and the sheet consisting of the vertical straps 711 forming separated layers and applying adhesive or heat welding at the cross over points. It also may further be formed, as shown in Figures 13 and 14, by way of the horizontal straps 711 and vertical straps (712) forming the whole sheet of the strap grid in one integrated
process through material injection, or stretching, or weaving and knitting, or casting, or pressing.
[0061] In the example shown in Figures 14 and 15, the connections and fixing of the strap grid and the woven or knitted fabric are realised by the edging strap 714, and the round knot 715 at the crossing of horizontal straps and vertical straps. The above connection and fixing may be pressed and welded using an ultra sound plastic welding machine to make sure the woven or knitted fabric is secured between the strap grid and the edging straps, and with the knots. Further, the connection and fixing of the strap grid and woven or knitted fabric can also use the method of weaving and knitting, or other methods/ which are not explained here, but will be readily understood by a person skilled in the art.
[0062] Specifically, the woven or knitted fabric 713 according to this embodiment of the invention, is attached on one side of the strap grid sheet. It is not located between the horizontal straps 712 and vertical straps 711. This arrangement has the advantage of relative ease of replacement of damaged woven or knitted fabric from the strap grid, since the material of the strap grid is much more durable than that of the woven or knitted fabric.
[0063] Preferably the polymer material used for the supporting grid and attached woven or knitted polymer fabric of any of the above embodiments is of a fire retardant formulation.
In Use
[0064] In use, the scaffolding safety mesh of the present invention may be deployed on scaffolding in the normal way. Thus rolls of the mesh at the required width are drawn along the upper and lower steel scaffold rails and posts and secured, either with tie wires, clips or cable ties as is common in the industry.
[0065] Alternatively, the mesh may be formed into panels of a size to suit standard scaffold spacing. In this case, perimeter edges of the mesh are folded over a metal frame 622 as shown in Figure 6 with the folded over edge 624 secured back to the main portion 620 of the sheet, again by any of the methods previously described.
[0066] The fact that the scaffolding safety mesh of the invention is entirely formed of suitable polymer materials such as polypropylene, polythene, polystyrene or polyester for example, provides for a very strong yet ultra-light mesh which is easily and safely handled in the awkward environment of scaffolding construction. The mesh thus provides a significant and useful contribution to the scaffolding industry. [0067] The above describes only some embodiments of the present invention and modifications, obvious to those skilled in the art, can be made thereto without departing from the scope of the present invention.