Mesh made of wire rings and method for making mesh made of wire rings

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TECHNICAL FIELD

This invention relates to a mesh made of wire rings and a method for making a mesh made of wire rings

The mesh according to the invention can advantageously be used as a rockfall barrier and/or as a covering of rock faces. However, even if this specification refers expressly to the above-mentioned use, the object of the invention may be susceptible to a more general use.

BACKGROUND ART

Meshes made of wire rings are widely used for covering rock slopes to protect the underlying zones from falling masses, flows of detritus and avalanche phenomena.

These meshes generally consist of a repeated series of wire rings linked to each other, having a diameter normally greater than or equal to 25 cm (centimetres).

According to a first prior art technique, each wire ring is made in the form of a strand with a multi-wire spheroidal cross section, and is obtained by winding and twisting on itself a steel wire along a substantially circular path. The wire is closed by splicing at the relative twisting start and finish ends, that is to say, at its two ends.

However, the splicing technique, even though it is excellent from the point of view of strength, can in no way be automated. In effect, this technique requires a manual processing and an extremely high precision in defining the length of the wire. In addition, if the diameter of the wire is equal to 2 mm the ends of the wire protrude from the strand with the possible injury of personnel involved in the installation of the mesh. In a second prior art technique, the ends of the wire with which the strand is obtained are clamped and kept in position by a metal clip.

However, this second prior art technique is also not free of drawbacks. Mainly, in many cases, the clip has not proved capable of resisting pulling, resulting in, with its failure, the withdrawal of the ends of the wire and the opening of the ring.

Also, on the one hand, the clip constitutes an additional element which is relatively expensive and, on the other hand, the size must be selected each time as a function of the quantity of wires twisted and the required strength.

In addition, a further drawback is linked to the fact that the installers of the barrier might easily injure themselves due to sudden contact with these clips or after accidental opening of at least one of these clips with the protrusion of ends of the wire from the strand.

In order to overcome the above-mentioned drawbacks it has been proposed that the clips be eliminated and that the two ends of the wire be closed independently, that is, the one at the start of the twist and the one at the end of the twist, repeatedly twisting each end around the strand and forming, in this way, two helical locking ends extending in opposite directions.

The production process of each ring of this type was, however, found to be difficult to automate due to the complex double twisting of the ends of the wire. For this reason, rings of this type are commonly finished by hand, with consequent increases in costs and loss of productivity.

AIM OF THE INVENTION

The aim of this invention is to provide a mesh made of wire rings and a method for making a mesh made of wire rings which overcome the above- mentioned drawbacks.

More specifically, the aim of this invention to provide a mesh made of wire rings and a method for making a mesh made of wire rings which are simple compared with the prior art whilst guaranteeing the closing seal of the ring.

In addition, the aim of this invention is to provide a mesh made of wire rings and a method for making a mesh made of wire rings which can be automated.

This aim is fully achieved by the mesh made of wire rings and the method for making a mesh made of wire rings according to this invention, as characterised in the appended claims. BRIEF DESCRIPTION OF DRAWINGS

The technical features and advantages of the invention are more apparent in the following description of a preferred but non-limiting embodiment of it. The description refers to the accompanying drawings, which are also provided purely by way of non-limiting example and in which:

- Figure 1 illustrates a piece of a mesh made of wire rings made according to this invention;

- Figures 2 to 5 illustrate in sequence respective stages for making a wire ring forming part of the mesh of Figure 1 ;

- Figure 6 illustrates a detail of the finished wire ring, shown in Figure 5;

- Figure 7 illustrates an alternative embodiment of the stage of Figure 4;

- Figure 8 illustrates a schematic front view of a machine for making and closing the strand according to this invention;

- Figure 9 illustrates a schematic top view of the machine shown in

Figure 8.

DESCRIPTION OF PREFERRED EMBODIMENTS

In Figure 1 , the numeral 1 denotes in its entirety a mesh made of wire rings, which comprises a repeated series of rings 2 made of wire linked to each other. More precisely, the mesh 1 comprises a plurality of rings 2 of wire which are linked together, and, as shown more clearly in Figures 2 and 3, each ring 2 is defined by a strand formed by a steel wire 3 repeatedly wound and twisted on itself in the form of a spiral.

If the mesh 1 is provided as a rockfall barrier and/or for the covering of rock faces, each ring 2 preferably has a diameter greater than or equal to 25 cm.

The wire 3 has a first end 4, which is not twisted in the making of the strand, and a second end 5 which is, on the other hand, repeatedly twisted in the form of a spiral in the making of the strand.

Once the strand has been made, both the ends 4 and 5 are outside the strand (Figure 4) and, according to a distinctive feature of the invention, are both wound in a helical fashion around the strand with the same direction of winding (Figures 5 and 6).

In some cases, the first end 4 is, in part, passing through the middle of the rest of the strand in such a way as to protrude outwardly relative to the strand.

The first end 4 of the wire 3 forms a first helical locking end comprising a plurality of first coils 6 clamped on the strand, and the second end 5 of the wire 3 forms a second helical locking end comprising a plurality of second coils 7 clamped on the strand.

As shown in Figures 4 and 7, in a step after making the strand and before closing the ends 4, 5, at least one of the two ends 4, 5 of the wire 3 is bent in such a way as to be alongside the other end 4, 5, defining a U-shaped configuration.

In the U-shaped configuration of Figure 4, immediately before closing the ends 4, 5 on the strand, the bending is performed on the first end 4 (the other end 5 adopting a non-deformed configuration, substantially tangential to the circumference defined by the strand) for placing the first end 4 alongside the second end 5.

Alternatively, in the U-shaped configuration of Figure 7, immediately before closing the ends 4, 5 on the strand, the two ends 4, 5 are superposed on each other at the base in such a way that the first end 4 is astride the second end. In other words, in this configuration there is a superposing of the two ends 4, 5 at the base (that is to say, at the point from which the ends 4, 5 protrude from the strand) and the ends 4, 5 are positioned in a configuration where they are alongside each other, ready to close the ends 4, 5 on the strand.

Preferably, after the closing by bending the ends 4, 5 on the strand, the first coils 6 and the second coils 7 are alternated with each other. This feature makes the ring 2 able to withstand high tensile stresses and, at the same time, easy to make in a mechanised manner. In effect, the coils of the two windings act in conjunction, blocking each other to make a considerable contribution to the overall resistance of the ring.

In order to make each ring 2 of wire, the respective wire 3 is wound and twisted repeatedly on itself to form an annular strand from which protrude the two ends 4 and 5 of the wire 3.

The two ends 4, 5, at the end of this first step, may be in a divergent configuration away from the strand. This would normally be due to the fact that the rigidity of the wire tends to keep the ends 4, 5 protruding from the strand in a configuration tangential to the annular line of extension of the strand.

The two ends 4 and 5 of the wire 3 are then moved near to one another to define a U-shaped configuration. This U-shaped configuration may extend in a radial or substantially radial direction relative to the centre of the annular line on which the ring extends, or it may be inclined relative to the radial direction and therefore be partly inclined or resting towards the strand (Figures 4 and 7).

This positioning alongside each other may occur by bending only one of the two ends 4, 5 or both, in such a way that the two ends 4, 5 adopt both the desired reciprocal configuration (U-shaped) and the desired orientation relative to the strand. This positioning alongside each other may bring the ends 4, 5 close to each other in such a way as to not superpose the ends 4, 5 at the base of them, that is to say, at the point where the ends 4, 5 protrude from the strand (Figure 4), or in such a way as to form a superposing of the ends 4, 5 at the base (Figure 7).

Subsequently, the ends 4, 5 are wound simultaneously and in a helical fashion around the strand in the same direction of winding. The step of simultaneously winding the two ends 4 and 5 of the wire 3 therefore occurs by alternating between them the first coils 6 and the second coils 7.

The rotational motion with which the two ends 4 and 5 are simultaneously wound is performed preferably and advantageously by a single gripping means, preferably of the gripper type, which grips and moves simultaneously the two ends 4, 5. The gripping means (not illustrated) are provided with an orbiting motion about the portion of strand on which the ends 4, 5 of the wire are bent.

Preferably, the pickup means are automatic.

This invention also relates to a machine 100 for winding rings 2 of wire in such a way as to make a strand as described in the above-mentioned method which is herebelow incorporated in its entirety.

More specifically, the machine 100 is illustrated in Figures 8 and 9 and comprises a base 101 for making the strand (Figure 9). More in detail, the base 101 is used to support the strand being formed. Preferably, the base 101 has a horizontal extension.

Also, the machine 100 comprises an unwinding roller 102 for the wire (Figure 9) rotating around the base 101 according to an annular path for making the rings 2 of wire. In detail, the machine 100 comprises an element 103 for supporting the unwinding roller 102 extending from a relative central portion 104 positioned at the central (and inner) zone relative to the strand to be formed to a respective lateral portion 105 located at an outer zone relative to the strand to be formed. The unwinding roller 102 is connected to the supporting element 103 in such a way that the unwinding of the wire occurs around the base 101 .

Preferably, the supporting element 103 has a "C" shape lying on a plane transversal (preferably orthogonal) to the base 101 (Figure 8). This shape "C" defines advantageously an opening 106 for extracting the strand formed.

In addition, the machine 100 comprises an automatic closing device 107 comprising means 108 for gripping the ends 4, 5 of the wire 3. More specifically, the automatic closing device 107 rotates around the portion of strand over which the ends 4, 5 of the wire 3 are bent in such a way as to wind them around the strand for making the closing.

Preferably, the gripping means 108 comprise a toothed wheel 109 having one or more grooves 1 10 in which the ends 4, 5 of the wire 3 are inserted. In addition, the machine 100 comprises a second toothed wheel 1 1 1 meshing with the first 109 for transmitting the motion to the first. In this way, the first toothed wheel 109 rotates around the strand to wind the ends 4, 5 of the wire around it.

As described above, it is evident that the invention allows robust rings 2 to be made which protect against accidental opening.

Also, the closing of each ring 2 is made with the same wire 3 which forms the ring 2 and by a single rotational winding movement, which, advantageously, may be mechanised and automated in a simple and inexpensive way.

The invention described above is susceptible of industrial application and may be modified and adapted in several ways without thereby departing from the scope of the inventive concept claimed herein. Moreover, all the details of the invention may be substituted for technically equivalent elements.