NZ209914A - Soil erosion control blanket:stitched mat of woodwool - Google Patents

Description

2099 1 4 Priority Date(s): ■?.. P. .?£]£ Complete Specification Filed: Ctese: &Q3/.QO./ ..4~.Qp?■PJ.lJ. P.P. .£o.<ri.rt.i.Jf.-?.;.. .cq.OM.$AQ.; ....

Publication Dale: P.O. Journal, No: .. ms.

NEW ZEALAND PATENTS ACT. 1953 No.: Date: COMPLETE SPECIFICATION STITCHED WOODWOOL MAT J^pAT€NTopp^g * 7 OCT 1984 ;XK/We, SEASONMAKERS (AUSTRALIA) PTY. LIMITED, a company incorporated under the laws of the State of New South Wales, ;Australia, of 99 Queen Street, Beaconsfield, New South ;Wales, Australia I ;I ;hereby declare the invention for which^/ we pray that a patent may be granted to y&effiis, and the method by which it is to be performed, ; ;to be particularly described in and by the following statement: - \ ;- 1 - ;a ;| ;.1 ;I ;I ;- 2 - ;099 1 4 ;The present invention relates to erosion .control and in particular to means to be applied to a ground surface for preventing or reducing its erosion and to a method of manufacturing such means. ;5 Methods of controlling erosion on steeply sloping ground have previously entailed such action as forming gutters running transverse to the slope, application of interlocking concrete, and other slab arrangements. Other methods of erosion control include the use of jute sacking 10 pegged to the soil and sprayed with bitumen and the use of bark and heavy wood chips covered with chicken wire. Such prior art methods are effective in arresting soil erosion but prevent and inhibit the growth of plants, grass and flora. ;15 An improved method of controlling erosion has been successfully employed by the present applicants, wherein a mat of woodwool fibres retained in a coherent structure by means of a bio-degradable mesh, with which at least some of the fibres interlock, is laid on the surface to be protected 20 and_pinned to the surface as required by stakes, peg[s or staples, such that the soil surface is stabilized until such time as vegetation can be re-established. Having re-established vegetation, the woodwool matting eventually breaks down to form a source of mulch for the new growth. 25 The present invention provides an improvement to the prior art woodwool mat and consists in a soil erosion control blanket comprising a mat of woodwool fibres, wherein some of the fibres interlock with one another, the mat being retained in a coherent structure by means of a plurality of 30 longitudinal rows of stitching extending through the mat. ;In the preferred form of the invention no further j means of retaining the mat in a coherent structure is ! ;I ;required, however, in some applications a stronger mat is j j ;required, in which case a second embodiment of the invention 35 is used wherein a mat of woodwool fibres is retained in a ;I * p 5 209914 coherent structure by means of a mesh, preferably at least some of the fibres interlock with the mesh and with others of the fibres, and wherein longitudinal rows of stitching are provided to further consolidate the structure.

Preferably, the mesh is bio-degradable.

The second embodiment of the invention is particularly effective in applications, such as in drainage gullies or waterways, where it is necessary to use woodwool matting with a mesh of plastics material applied to one side in 10 order that the mat does not break up and wash away and where stitching of such matting aids in the prevention of movement or washing out of woodwool fibres from beneath the net. Woodwool mat without mesh applied, which is reinforced only by longitudinal rows of stitching, is suitable for use in 15 the stabilization of sand dunes where due to the flatness and lower degrees of slopes, the mesh is not necessary to help hold the woodwool fibres in position or to help retain the embankment or sand dune in any way and therefore the cost of stabilizing sand dunes can be reduced by using 20 woodwool mat which does not have the mesh of plastics material applied.

According to a second aspect, the present invention consists in a method of forming a soil erosion control blanket comprising the steps of continuously producing a mat 25 of intertangled woodwool fibres, said mat having a substantially constant cross-sectional area, and passing said mat through stitching means to insert a plurality of longitudinal rows of stitches extending through said mat.

In the case of the second embodiment of the stitched 30 woodwool mat referred to previously, the method of producing the woodwool mat includes the step of feeding the mat of intertangled fibres onto a length of mesh and may also include the step of kneading the woodwool fibres against said mesh to secure same by interlocking at least some of 35 the fibres with the mesh. The stitches are then inserted 2099 14 through the woodwool mat and the mesh to further improve the coherence of the structure. It may be preferred for the mesh to be formed from bio-degradable material.

Embodiments of the invention will now be described by 5 way of example with reference to the accompanying drawings in which:- Figure 1 illustrates a length of woodwool mat according to the preferred embodiment of the present invent ion; Figure 2 illustrates a length of mat according to a second embodiment of the present invention; and Figure 3 schematically illustrates an apparatus for manufacturing both embodiments of the invention.

Referring to Figure 1(a) a segment of a continuous 15 length of woodwool mat made in accordance with the preferred embodiment of the present invention is illustrated in plane view, while a sectional elevation of the mat of Figure 1(a) is illustrated in Figure 1(b). The woodwool fibre mat comprises a mass of woodwool fibres 10, each preferably in 20 the^order of 450 mm long when fully extended, the woodwool fibres being produced in such a manner that in the free state they form coils like clock springs, and each of the woodwool fibres in the mat being interlinked with a substantial number of others of the woodwool fibres in order 25 to provide a reasonably coherent structure. Typically the woodwool fibre mat is in the order of 1.2 meters wide and has a thickness ranging between 10 and 65 mm depending upon the application to which it is to be put. The preferred embodiment of the invention is reinforced longitudinally by 30 inserting rows of chain stitches 11 through the mat, these stitches providing a degree of resistance to longitudinal extension of the mat in use and also binding the fibres of the mat together to reduce tangling of fibres from adjacent layers of matting when the mat is rolled for storage and 35 transportation. Typically, the spacing between rows of 2 0 99 f 4 stitches 11 is in the order of 50 mm, however, this distance may be varied to suit the individual requirements of the project for which the matting is produced.

In some instances, additional strength is required in the transverse direction of the mat, in which case the matting is produced with a mesh of plastics material applied to one surface, as illustrated in the sectional elevation of Figure 2 wherein a mesh 12 has been applied to the bottom surface of the mat. Various sizes of mesh may be used to reinforce the matting, however, typically a mesh having openings in the order of 75 mm in diameter will be used. The stitching 11 extends through the woodwool mat and through the mesh 12 to hold the mesh and the matting together and additional cohesion is provided by intertwining of the woodwool fibres and the mesh. The matting of Figure 2 will typically be used in situations where the mats are to be laid across a slope which exceeds 35° from the horizontal. Under such circumstances transverse forces on the matting would tend to cause longitudinal separation of theTmat illustrated in Figure 1, whereas the mesh 12 incorporated in the mat of Figure 2 provides resistance to transverse extension and therefore reduces the chance of separation occuring in the longitudinal direction. Turning now to Figure 3, the apparatus required to manufacture the woodwool matting of Figures 1 and 2 is schematically illustrated, wherein a shredding machine 21 comprising cutters (not shown) made in accordance with our earlier Australian Patent No. 248,949, supplies shredded woodwool to a conveyor 22 which then feeds the woodwool into a fan 23. The woodwool is then blown via a duct 24 into a regulated storage hopper 25 which is tapered towards its lower end and works in conjunction with the kneading rollers 29 to regulate the thickness of the mat produced. When producing the embodiment of Figure 2, plastic mesh 12 is fed onto conveyor 26 from a supply roll 27 and an adjustable pressure 7099 1 4 plate 28 ensures contact of the woodwool fibres with the mesh 12 before being fed into the kneading rollers 29. In the kneading rollers 29 the woodwool fibres are compressed to promote further interlinking of fibres and in the case 5 where mesh 12 is being applied, to also promote interlinking between the fibres and the mesh. After leaving the kneading rollers 29 the woodwool mat passes through a stitching machine 31 which inserts longitudinal rows of continuous stitching through the matting, the needles of the stitching 10 machine typically being placed to provide 50 mm intervals between stitching rows, but other intervals being achievable by removing selected needles from the machine. After passing through the stitching machine 31 the woodwool matting passes through a guillotine 32 and is then rolled 15 onto a roll 33. When the desired length of matting has been rolled onto roll 33, the matting is chopped by guillotine 32 and the completed roll removed to storage ready for a new roll to be formed.

It will be recognised by persons skilled in the art 20 that numerous variations and modifications may be made to the invention as described above without departing from the spirit or scope of the invention as broadly described.

Claims (8)

1099 | 4 WHAT CLAIM IS:

1. A soil erosion control blanket comprising a mat of woodwool fibres, wherein some of the fibres interlock with one another, the mat being retained in a coherent structure by means of a plurality of longitudinal rows of stitching extending through the mat.

2. A soil erosion control blanket as claimed in claim 1 comprising a mesh on one surface of the blanket, said stitching extending through the mat and the mesh.

3. A soil erosion control blanket as claimed in claim 2 wherein at least some of the fibres interlock with the mesh and others of the fibres.

4. A method of forming a soil erosion control blanket comprising the steps of continuously producing a mat of intertangled woodwool fibres, said mat having a substantially constant cross-sectional area, and passing said mat through stitching means to insert a plurality of longitudinal rows of stitches extending through said mat.

5. A method as claimed in claim 4 comprising applying said mat of intertangled woodwool fibres to a mesh before stitching through the mat and the mesh.

6. " A method as claimed in claim 5 wherein the mat is kneaded onto the mesh to interlock some of the fibres with the mesh.

7. A soil erosion control blanket substantially as hereinbefore described with reference to Figs. 1 or 2 of the accompanying drawings.

8. A method of forming a soil erosion control blanket substantially as hereinbefore described with reference to Fig. 3 of the accompanying drawings. N.Z. PATENT OFFICE 17 OCT 1984 W$/their authppfS^SAjpents,