Wire netting, a process and a device for manufacturing the wire netting

Abstract

A hexagonal wire netting, a process for manufacturing such a wire netting and a device for manufacturing a hexagonal wire netting, the device including an assembly of tubes for leading the wires of which every other is twisted into a spiral shape, a spindle assembly and a drum receiving the wire netting, the drum being provided with detent elements. Between each tube leading the spirally twisted wire and the cooperating spindle a straightening guide is located having an inlet opening cooperating with the tube and an outlet opening cooperating with the spindle. The detent elements are arranged on the drum in such a way that the produced wire netting has meshes in which the proportion of the width to the length is less than 0.75.

Claims

1. A device for manufacturing a hexagonal wire netting, the hexagonal wire netting comprises wires, the device comprising: a tube assembly comprising tubes for leading the wires, every other tube having wires twisted into a spiral shape forming spirally twisted wires, a spindle assembly comprising spindles, a drum receiving the wire netting, the drum comprising detent elements, each spindle of said spindle assembly being configured to lead one wire passing therethrough and fed by a cooperating tube of the tubes, each of the spindles of said spindle assembly being alternately translated back and forth and rotated by 540 degrees, so that the wires leaving the spindles are braided in at least 1.5 fold braids forming the hexagonal wire netting to be subsequently received by the drum, a straightening guide disposed between each of the every other tube in the tube assembly having the spirally twisted wires and a respective one of the spindles of the spindle assembly, the straightening guide having an inlet opening cooperating with a respective one of the tubes of the tube assembly and an outlet opening cooperating with the respective one of the spindles of the spindle assembly, and wherein said detent elements are arranged on the drum in such a way that the hexagonal wire netting has meshes having a width to length ratio of less than 0.75.

2. The device according to claim 1, wherein the straightening guide comprises a wall in a shape of a truncated cone, the straightening guide having a smaller edge which constitutes a central outlet opening cooperating with the respective one of the spindles of the spindle assembly, and a larger edge which constitutes a central inlet opening cooperating with an outlet of the respective one of the tubes of the tube assembly.

3. The device according to claim 2, further comprising a guiding groove defined in an inner side of the wall in a shape of a truncated cone for assisting in straightening of the wires prior to being introduced into the spindles of the spindle assembly.

4. The device according to claim 1, wherein the straightening guide comprises a hollow cylinder having an inlet edge and an outlet edge, with the straightening guide comprising an inlet wall in a shape of a truncated cone, the straightening guide having a larger edge of which is aligned with the inlet edge of the hollow cylinder and constitutes an inlet opening cooperating with an outlet of the respective one of the tubes of the tube assembly, and a smaller edge which constitutes an inlet opening leading to the hollow cylinder, with the straightening guide further comprising an outlet wall in a shape of a truncated cone, the outlet wall having a larger edge which constitutes an outlet edge of the hollow cylinder, and a smaller edge which constitutes an outlet opening cooperating with the respective one of the spindles of the spindle assembly.

5. The device according to claim 4, wherein an inner side of said inlet wall in a shape of a truncated cone comprises a guiding groove for assisting in straightening of the wires prior to being introduced in the spindles of the spindle assembly.

6. The device according to claim 1, wherein the straightening guide is made of a plastic material.

7. A process for manufacturing a hexagonal wire netting in a device, the wire hexagonal wire netting comprising wires, the device comprising a tube assembly comprising tubes for leading the wires, every other tube having wires twisted into a spiral shape forming spirally twisted wires, a spindle assembly comprising spindles, a drum receiving the wire netting, the drum comprising detent elements, and each of the spindles of the spindle assembly being configured to lead one wire passing therethrough, the one wire being fed by a cooperating tube of the tubes of the tube assembly, the method comprising: forming the wires using high carbon steel having tensile strength in a range of 1500-1900 MPa, straightening the wires that are spirally twisted in the tubes before feeding them into the spindles of the spindle assembly, and feeding all the wires into the spindles of the spindle assembly, and alternately translating each of the spindles of the spindle assembly back and forth and rotating each of the spindles of the spindle assembly by 540 degrees, so that the wires leaving the spindles are braided in at least 1.5 fold braids so as to form the hexagonal wire netting to be subsequently received by the drum, wherein the hexagonal wire netting comprises meshes having a width to length ratio of less than 0.75.

8. The process according to claim 7, wherein the wires made of steel having carbon content from 0.71% to 1% are used.

9. The process according to claim 7, wherein the wires are provided with an anti-corrosion coating comprising a zinc-aluminum coating in the amount of min. 150 g/m2.

10. The process according to claim 7, wherein the wires of stainless steel are used.

Description

(1) Exemplary embodiments of the wire netting and the device for the manufacture of the wire netting according to the invention are shown in the drawings in which:

(2) FIGS. 1A, 1B, 1C, 1D, 1E, and 1F show fragments of the wire netting according to the prior art;

(3) FIG. 1G shows a fragment of the wire netting according to the invention;

(4) FIG. 2 shows a schematic view of a fragment of the device according to the invention;

(5) FIG. 3 shows schematically a first embodiment of the straightening guide;

(6) FIG. 4 shows schematically a second embodiment of the straightening guide;

(7) FIG. 5 shows a detailed view of the connection between a tube and a spindle in the device according to the invention;

(8) FIG. 6 shows an enlarged view of a braid of two wires in a final wire netting according to the invention

(9) FIG. 7 shows a schematic view of a drum of the device according to the invention.

(10) As may be seen in FIG. 1G, showing a fragment of the wire netting 7 according to the invention, each hexagonal mesh of the wire netting 7 has two sides with braids and four sides without the braids. Further, each mesh has six corners: there are four corners where the side with a braid meets the side without it, and two corners (opposite to each other) where two sides without the braids meet. The width A of a mesh is defined here as the distance between the two sides with the braids, and the length B of a mesh is defined as the distance between the two corners where two sides without the braids meet.

(11) The inventors have established that a wire made of high carbon steel having tensile strength in the range of 1500-1900 MPa may be used for manufacturing the hexagonal wire netting 7 with at least 1.5 fold braids provided that the wires have been straightened before being introduced into the spindles and that said wires are not exceedingly bent later on the receiving drum. Therefore, in the meshes of the wire netting 7 according to the invention the proportion of the width A to the length B is less than 0.75. Basing on experiments it has also been established that the most advantageous content of carbon in the steel used for the wire is in the range of 0.71% to 1%, because such a wire is sufficiently resistant and at the same time ductile to enable the manufacture of the wire netting 7 according to the invention. A higher content of carbon would make the wire too brittle while a lower content thereof would make it too ductile and with a too low tensile strength.

(12) A preferable thickness of a wire for the manufacture of the wire netting 7 according to the invention is about 2.0 to about 4.0 mm.

(13) FIG. 2 shows a schematic view of a fragment of the device according to the invention.

(14) The wires 1 are brought from delivery stations 2 by means of guiding elements 3 and 4, to a tube assembly 5. The tubes 5 of the tube assembly form a row. In every other tube of the row a wire is being twisted into a spiral shape, i.e., in every other tube the wire remains straight. In FIG. 2, the wire 1 in the tube 5 is being twisted. Downstream of the assembly of the tubes 5 (as shown in FIG. 2 above the tube assembly 5) a spindle assembly 6 is located, so that the wire 1 leaving each tube 5 is passed to a cooperating spindle 6. The neighboring wires are braided with each other by the spindles 6 (the same as in the above-described state of art machine) and from the spindles 6 the ready wire netting 7 is passed to the drum 8 and then wound on a roll 9.

(15) A specific feature of the device according to the invention is that it is provided with wire straightening guides 10. Between each tube 5, in which the wire 1 is being spirally twisted and its cooperating spindle 6, the straightening guide 10 is located.

(16) In the first and simplest embodiment shown in FIG. 3, the straightening guide 10 is formed by a wall in the shape of truncated cone 11, the smaller edge of which constitutes a central outlet opening 12 cooperating with the spindle 6, while its larger edge constitutes a central inlet opening 13 cooperating with the outlet of the tube 5.

(17) FIG. 4 shows an embodiment in which the straightening guide 10 comprises a hollow cylinder 14 having an inlet edge and an outlet edge, and being provided inside with an inlet wall 17 in the shape of a truncated cone, the larger edge of which is aligned with the inlet edge of the hollow cylinder 14 and constitutes the inlet opening 15 cooperating with the outlet of the tube 5. The smaller edge of the inlet wall 17 constitutes the inlet opening 18 leading to the inside of the hollow cylinder 14. The hollow cylinder 14 is further provided on its outside with an outlet wall 19 in the shape of a truncated cone, the larger edge of which constitutes the outlet edge of the hollow cylinder, while the smaller edge of which constitutes the central outlet opening 20 cooperating with the spindle 6.

(18) The straightening guide 10, 10 is preferably made of a plastic material. In order to facilitate the straightening of the wire 1 passing through the guide 10 or 10, a spiral guiding groove 22 may be located on the internal side of the truncated cone 11 or respectively 17. An exemplary spiral guiding groove 22 is visible as a broken line in FIGS. 3 and 4.

(19) FIG. 5 shows an enlarged view of a detail D (circled in FIG. 2) of a fragment of the machine between the tube 5 and the spindle 6, where the straightening guide 10 is mounted.

(20) Due to the provision of the straightening guides 10, 10 the twisted wires 1 that are made of a relatively stiff steel having high tensile strength, are being straightened prior to being introduced to the spindles 6. Subsequently, the spindles 6 impose at least 1.5 fold braiding of the neighboring wires with each other. An exemplary braid of two wires 1 is shown in FIG. 6.

(21) Another important feature of the invention is the use of the receiving drum 8 shown in FIG. 7, having detent elements 21 arranged in such a way that the produced wire netting 7 is formed with hexagonal meshes in which the proportion of the width A to the length B is less than 0.75.

(22) The use of the specific straightening guides 10, 10 and the special arrangement of the detent elements 21 on the receiving drum 8 results in that the high tensile-strength wire does not brake during the at least 1.5 fold braiding which enables formation of the hexagonal netting.

(23) Thanks to the hexagonal structure and the at least 1.5 fold braiding the wire netting will not unbraid even in case of a breakage of one wire. Upon the breakage of one individual wire (as schematically shown by scissors in FIG. 1G) the forces are transferred by the neighboring wires and the unbraiding of the wire netting is prevented by the neighboring braids because the netting is made of high tensile-strength wires. The edges of a wire netting sheet are provided with border wires or ropes, which are also made of a high tensile-strength steel and ensure an orderly shape of the netting edges.

(24) The wire netting 7 according to the invention may be a component of a system in which conventional plates/washers are used for pressing the mounted wire netting to the slope (not shown).

(25) As the wire netting 7 according to the invention is woven from the high tensile-strength wires, it tends to self-constrain upon braiding of the wires. Consequently, the arising hexagonal structure is elastic and the width of the band of the netting received by the drum is smaller than the maximal possible width of the band when stretched. Such an elastic structure is a sort of an energy absorber and it may be mounted on an embankment base for the purpose of catching rock chunks without the need to use absorbing spring ropes.

(26) An additional advantage of the invention is that the wire netting 7 according to the invention enables continuous protection of large surfaces. On some embankments, the wire netting may be formed of a continuous material on the whole length of the embankment. For example, a rolled wire netting having a length of 30 m is made of continuous 40 m long wires, the 10 m reduction being caused by the hexagonal shape of the meshes. On the other hand, rhomboidal nettings may not be manufactured of the wires longer than about 4 m.