EP1501971B1 - Net structure formed by knitted metal wires - Google Patents

Abstract

The invention concerns a net structure ( 5, 50 ) wherein each mesh comprised therein is linked to the laterally adjacent mesh by a breakable junction piece ( 3 ), said junction piece ( 3 ) having a rupture threshold markedly lower than that of the wires constituting the net structure.

Description

The present invention relates to a net structure formed by knitting wire ropes, a protective net against the fall of one or more heavy bodies, such as blocks of stone, formed from said structure, and a protective device against the falls of such heavy bodies.

It is well known to use anti-submarine net to form the net of a protection device against falling rocks or other bodies likely to fall on an area to protect. The stock of this type of net, however, tends to run out, and the cost of making nine such nets is too important to qualify. Some of these nets also have uncertain origins, even unknown, which does not give all the assurances required for their resistance in this specific application.

There are also nets formed by weaving or knitting wire ropes. Existing nets of this type have the disadvantage of having only a very small power dissipation of the energy transmitted by a block of stone or other similar bodies. This results in a tremendous effort transmission at the anchoring points of the nets, which can be caused to break.

The present invention aims to overcome the aforementioned drawbacks, by providing a mesh structure formed by knitting wire ropes, having a high power dissipation energy transmitted by the fall of a body while remaining relatively inexpensive to manufacture.

According to the invention, each mesh that comprises this net structure is connected to the laterally adjacent mesh by a rupturable junction piece, this junction piece having a breaking threshold much lower than that of the cables constituting the structure of the net.

The breaking point of the joining piece can in particular be of the order of a quarter of the breaking threshold of these cables.

The connecting pieces make it possible to keep the meshes normally in a position close to each other, so that, for a given number of meshes, the surface of the net according to the invention is smaller than the surface of a net of the same knitting structure, for the same number of stitches without joining pieces.

During the fall of a body, in particular a block of stone, the connecting pieces break successively, from the point of impact and radiating from it, releasing the assembly of meshes. These successive ruptures allow to absorb a portion of the energy transmitted by the body and also allow to release a possibility of additional deformation of the net. This additional deformation generates, when it occurs, friction and twisting of the cables, which contribute to the absorption of the energy transmitted by the fall of the body.

The rupture of the connecting pieces is interrupted when the energy transmitted by the fall of the body becomes insufficient to cause these breaks.

Thus, thanks to the combination of a knitting of metal cables and these connecting pieces, the net structure according to the invention allows an absorption of greater energy without breaking the cables, so without breaking the integrity of the cables. the structure of the net.

Preferably, the knitting of the cables is of the "Jersey" type.

The connecting pieces may comprise open metal sleeves crimped on the cables or parts of the kind of supplementary links for the chain.

According to a first embodiment of the invention, each cable or portion of cable constituting a row of meshes forms successive "S" defining circular inverted loops, and the joining pieces collect the adjacent cable strands of the adjacent meshes. ; each cable or portion of cable constituting the row of cells immediately adjacent to the aforementioned one has a structure identical to that of this first row of stitches, and the portion of cable forming a stitch of this second row of stitches fits into a corresponding stitch of said first row of stitches, passes behind the strands of the two adjacent stitches of this first row of stitches and comes out of the adjacent stitch.

• une portion de câble formant une maille d'une rangée de mailles considérée rentre dans une maille correspondante de l'une des rangées de mailles adjacente, passe derrière les brins des deux mailles adjacentes de cette rangée de mailles et ressort de la maille adjacente, et
• une portion de câble formant une maille de cette même rangée de mailles considérée sort d'une maille correspondante de l'autre des rangées de mailles adjacente, passe devant les brins des deux mailles adjacentes de cette rangée de mailles et rentre dans la maille adjacente.

Alternatively, alternately from one row of stitches to another,

• a cable portion forming a mesh of a given mesh row enters a corresponding mesh of one of the adjacent stitch rows, passes behind the strands of the two adjacent stitches of this stitch row and exits from the adjacent stitch, and
• a portion of cable forming a mesh of the same row of stitches considered out of a corresponding mesh of the other rows of mesh adjacent, passes in front of the strands of the two adjacent stitches of this row of stitches and enters the adjacent mesh.

According to another embodiment of the invention, each cable or portion of cable constituting a row of meshes forms successive piriform loops, in "tiny e", and the connecting pieces collect the adjacent cable strands of the adjacent meshes; each cable or portion of cable constituting the row of cells immediately adjacent to the aforementioned one has a structure identical to that of this first row of stitches, the cable portion forming a stitch of this second row of stitches falling into a corresponding stitch of said first row of stitches row of stitches, passing behind the two strands of the two adjacent stitches of this first row of stitches and emerging from the adjacent stitch.

The net according to the invention is formed from the structure described above.

When it has a length and a width, especially when it has a rectangular shape, the mesh length can be oriented parallel or perpendicular to the length of the net.

• le filet présente une longueur de 10 m et une largeur de 6 m ;
• le diamètre de la partie circulaire que forme chaque maille est de 350 mm ;
• le diamètre des câbles utilisés est de 12 mm ;
• l'élasticité des câbles est au maximum de 1,15 % avant rupture ;
• le seuil de rupture des câbles est de 84 kN ;
• le seuil de rupture des pièces de jonction est de l'ordre de 20 kN.

In a particular embodiment of a net according to the invention:

• the net has a length of 10 m and a width of 6 m;
• the diameter of the circular part formed by each mesh is 350 mm;
• the diameter of the cables used is 12 mm;
• the elasticity of the cables is at most 1.15% before breaking;
• the breaking point of the cables is 84 kN;
• the breaking point of the connecting pieces is of the order of 20 kN.

The protection device according to the invention comprises a net as defined above.

• La figure 1 est une vue en plan d'une portion de câble qu'elle comprend selon une première forme de réalisation, constituant une série de boucles successives destinées à former des mailles ;
• la figure 2 est une vue en plan de la structure de filet incluant une série de portions de câbles de même conformation que celle montrée sur la figure 1, tricotées les unes aux autres ;
• la figure 3 est une vue en plan d'une structure similaire, avec une variante de réalisation au niveau du tricotage ;
• la figure 4 est une vue en plan d'une portion de câble que comprend la structure de filet selon une deuxième forme de réalisation, constituant une série de boucles successives destinées à former des mailles ;
• la figure 5 est une vue en plan de la structure de filet incluant une série de portions de câbles de même conformation que celle montrée sur la figure 4, tricotées les unes aux autres ;
• la figure 6 est une vue en plan d'un filet formé à partir de la structure montrée sur la figure 2, et
• la figure 7 est une vue en plan d'un autre filet formé à partir de la structure montrée sur la figure 2.

For a good understanding, the invention is again described below with reference to the attached schematic drawing showing, by way of non-limiting examples, two possible embodiments of the net structure that it relates.

• The figure 1 is a plan view of a portion of cable it comprises according to a first embodiment, constituting a series of successive loops for forming meshes;
• the figure 2 is a plan view of the net structure including a series of cable portions of the same conformation as that shown in FIG. figure 1 knitted to each other;
• the figure 3 is a plan view of a similar structure, with a variant embodiment at the knitting level;
• the figure 4 is a plan view of a portion of cable that comprises the net structure according to a second embodiment, constituting a series of successive loops for forming meshes;
• the figure 5 is a plan view of the net structure including a series of cable portions of the same conformation as that shown in FIG. figure 4 knitted to each other;
• the figure 6 is a plan view of a net formed from the structure shown on the figure 2 , and
• the figure 7 is a plan view of another net formed from the structure shown on the figure 2 .

The figure 1 represents a portion of cable 1 forming successive "S" which define inverted loops 2 of circular shape. The adjacent cable strands 2a of two adjacent loops 2 are joined by connecting pieces 3 formed by metal sleeves crimped onto these strands 2a.

The joining pieces 3 are ruptible and have a breaking threshold much lower than that of the cable 1, in particular of the order of a quarter of the breaking threshold of this cable 1.

For the realization of a net having a length of 10 m and a width of 6 m adapted to equip a protective device against heavy body falls, such as blocks of stone, the diameter of the circular part that forms each loop 2 is 350 mm, the diameter of the cable 1 used is 12 mm, the elasticity of this cable 1 is at most 1.15% before breaking, the breaking point of the cable 1 is 84 kN, and the threshold breaking of the connecting pieces 3 is of the order of 20 kN.

The figure 2 represents a net structure 5 including a series of six portions of cables 1a to 1f of the same conformation as that shown on FIG. figure 1 , knitted to each other, each loop 2 forming a mesh of this knit. As it appears, each mesh of a portion of cable considered enters a corresponding mesh of the portion of cable immediately adjacent, passes behind the strands 2a of the two adjacent meshes of this cable portion and out of the adjacent mesh.

The figure 3 represents a similar structure 5, in which the knitting of the portion 1b to the portion 1a, of the portion 1d to the portion 1c and the portion 1f to the portion 1e differs however: each mesh of a portion 1b , 1d or 1f fate of a corresponding mesh of the portion 1a, 1c or 1e respectively, passes in front of the strands 2a of the two adjacent cells of this cable portion 1a, 1c or 1e and enters the adjacent mesh.

The knitting of portion 1b to portion 1c and portion 1d to portion 1e is identical to that described above.

The figure 4 represents a portion of cable 10 forming successive piriform loops 12, in "tiny e". The adjacent cable strands 12a of two adjacent loops 12 are joined by joining pieces 3 identical to those described above.

The figure 5 represents a net structure 50 including a series of six cable portions 10a to 10f of the same conformation as that shown on FIG. figure 4 , knitted to each other, each loop 12 forming a mesh of this knit. As it appears, each mesh of a portion of cable considered enters a corresponding mesh of the cable portion immediately adjacent, passes behind the strands 12a of the two adjacent cells of this cable portion and out of the adjacent mesh.

The Figures 6 and 7 show rectangular nets 100, 101 formed from the structure 5. In the case of the net 100 shown on the figure 6 , the length of the stitches 2 is oriented parallel to the length of the net, whereas, in the case of the net 101 represented on the figure 7 , the mesh length 2 is oriented perpendicular to the length of the net.

As described above, the invention provides a decisive improvement to the prior art by providing a net structure 5, 50 having a high power dissipation of the energy transmitted by the fall of a body.

In fact, the connecting pieces make it possible to maintain the meshes normally in a position close to each other, so that, for a given number of meshes, the surface of the net according to the invention is smaller than the surface of a mesh. net of the same knitting structure, for the same number of stitches.

During the fall of a body, including a block of stone when the net is equipped with a device for protection against falling rocks, the junction pieces 3 break successively from the point of impact and radiating from this one, releasing the assembly of the meshes. These successive ruptures allow to absorb a portion of the energy transmitted by the body and also allow to release a possibility of additional deformation of the net. This additional deformation generates, when it occurs, friction between the cables, which contribute to the absorption of the energy transmitted by the fall of the body.

The rupture of the connecting pieces 3 is interrupted when the energy transmitted by the fall of the body becomes insufficient to cause these breaks.

Thus, thanks to the combination of a knitting of metal cables and these connecting pieces, the net structure according to the invention allows absorption of the energy transmitted by said body without breaking the cables, so without breaking the integrity of the net structure.

It goes without saying that the invention is not limited to the embodiment described above by way of example but that it embraces on the contrary all variants within the scope of protection defined by the claims appended.

Claims (12)

1. Net structure (5, 50) formed by knitting of metal cables, characterised in that each mesh which this net structure (5, 50) comprises is connected to the laterally adjacent mesh by a breakable joining piece (3), this joining piece (3) having a rupture threshold which is distinctly lower than that of the cables which constitute the net structure (5, 50).
2. Net structure (5, 50) according to claim 1, characterised in that the rupture threshold of the joining piece is approximately a quarter of the rupture threshold of these cables.
3. Net structure (5, 50) according to claim 1 or claim 2, characterised in that the knitting of the cables is of the "Jersey" type.
4. Net sLrucLure (5, 50) according to one of claims 1 to 3, characterised in that the joining pieces (3) comprise open metal sleeves which are crimped onto the cables.
5. Net structure (5, 50) according to one of claims 1 to 4, characterised in that the joining pieces (3) comprise pieces of the type such as additional links for a chain.
6. NeL structure (5) according to one of claims 1. to 5, characterised in that each cable or portion of cable (1a to 1f) which constitutes a row of meshes forms successive "Ss" which define inverted loops (2) with a circular form, and in that the joining pieces (3) gather together the adjacent cable strands (2a) of the adjacent meshes; each cable or portion of cable (1b to 1e) which constitutes Lhe row of meshes immediately adjacent to Lhe aforementioned one has a structure which is identical to that of this first row of meshes, and the portion of cable which forms a mesh of this second row of meshes enters a corresponding mesh of the said first row of meshes, passes behind the strands (2a) of the two adjacent meshes of this first row of meshes, and emerges from the adjacent mesh.
7. Net structure (5) according Lo one of claims 1 Lo 5, characterised in that each cable or portion of cable (1a to 1f) which constitutes a row of meshes forms successive "Ss" which define inverted loops (2) with a circular form, and in that the joining pieces (3) gather together the adjacent cable strands (2a) of the adjacent meshes; in an alternating manner from one row of meshes to another, a portion of cable which forms a mesh of a row of meshes concerned enters a corresponding mesh of one of the adjacent rows of meshes, passes behind the strands (2a) of the two adjacent meshes of this row of meshes, and emerges from the adjacent mesh, and a portion of cable which forms a mesh of this same row of meshes concerned emerges from a corresponding mesh of the other one of the adjacent rows of meshes, passes in front of the strands (2a) of the two adjacent meshes of this row of meshes, and enters the adjacent mesh.
8. Net structure (50) according to one of claims 1 to 5, characterised in that each cable or portion of cable (10a to 10f) which constitutes a row of meshes forms successive pear-shaped loops (12) in the form of a "lower case "e"", and in that the joining pieces (3) gather together the adjacent cable strands (12a) of the adjacent meshes; each cable or portion of cable (1.0b to 10e) which constitutes the row of meshes immediately adjacent to the aforementioned one has a structure which is identical to that of this first row of meshes, and the portion of cable which forms a mesh of this second row of meshes enters a corresponding mesh of the said first row of meshes, passes behind the two strands of the two adjacent meshes of this first row of meshes, and emerges from the adjacent mesh.
9. Net (100, 101) for protection against falling of one or more heavy bodies, such as blocks of stone, formed from the said structure (5, 50) according to one of claims 1 to B.
10. Net (100) according to one of claims 1 to 9, characterised in that it has a length and width, and in that the length of the meshes is oriented parallel to the length of the net.
11. Net (101) according to one of claims 1 to 9, characterised in that it has a length and width, and in that the length of the meshes is oriented perpendicularly to the length of the net.
12. Device for protection against falling of one or more heavy bodies, such as blocks of stone, comprising a net (100, 101) according to one of claims 9 to 11.

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