GB2259722A - Security fencing - Google Patents

Abstract

Fencing material comprises overlying wires (66, 70) arranged in a mesh configuration and welded to one another, at least one length of barbed tape (60) being welded to some of the wires. <IMAGE>

Description

1 z_0 - 25 2r C-. 1 FENCING MATERIAL AND ITS METHOD OF MANUFACTURE.

Page 1 This invention relates generally to fencing material and is particularly concerned with upgrading the security effect of fencing material known as welded mesh.

The invention provides fencing material which includes a plurality of overlying wires which are welded to one another to form a mesh, and at least one length of barbed tape which is welded to transverse wires in the mesh.

Barbed tape' as used in this specification includes a construction in which a length of metallic tape is formed with barb formations and is crimped around a core wire, and a construction which comprises a planar length of metallic tape, with barb formations, with the core wire dispensed with.

The length of barbed tape may be elongate and extend in the longitudinal direction of the mesh. This may be at right angles to the transverse wires. The length of barbed tape may be substantially parallel to plain wires which are welded to the transverse wires.

The length of barbed tape may be located at any convenient position across the width of the mesh. For example, the barbed tape may be Page 2 located at an intermediate location. It is preferred, however, that the barbed tape is located at least along one longitudinal edge of the mesh.

The number of lengths of barbed tape, included in the mesh, may be varied according to the deterrent effect which is required. For example, two or more adjacent lengths of barbed tape may be secured to the mesh along one longitudinal edge. To obtain an increased deterrent effect, two or more lengths of barbed tape are secured to the mesh along each of its longitudinal edges.

The aforementioned possible configurations, with varying numbers of lengths of barbed tape, are given merely by way of example and are not limiting.

The invention also provides fencing material which comprises a plurality of overlying plain wires which are welded to one another to form an elongate mesh and at least one elongate length of barbed tape located along at least one longitudinal edge of the mesh.

The barbed tape may include a core wire which is brought into contact with, and which is welded directly to, respective transverse wires in the mesh.

1 Page 3 The invention also extends to a method of making fencing material which includes the steps of feeding at least one length of barbed tape and a plurality of lengths of wires, all of which are parallel to and spaced from one another, through a welding station in steps, and, for each step movement, at the welding station, welding a transverse wire to the barbed tape and to each of the lengths of wires.

The method may include the step of drawing the barbed tape directly f rom a machine which is used to manufacture the barbed tape. Thus, the feeding of the length of barbed tape, in steps to the welding station, may be synchronized to the manufacture of the barbed tape. The barbed tape may be orientated so that, if it has a core wire this is brought into contact with, and hence is welded directly to, the respective transverse wires.

The invention is further described by way of examples with reference to the accompanying drawings in which:

Figure 1 is a plan view of portion of fencing material according to one form of the invention, Figure 2 schernatically depicts in plan the method of manufacturing the fencing material of Figure 1, Page 4 Figure 3 is an enlarged plan view of portion of a length of barbed tape during the process of manufacturing the fencing material, as shown in Figure 2, Figure 4 is an enlarged cross sectional view of portion of the fencing material of Figure 1, taken on the line 4-4, and Figure 5 is a view similar to Figure 1 of fencing material according to a different embodiment of the invention.

Figure 1 of the accompanying drawings illustrates a portion 10 of fencing material which comprises a plurality of cross wires 12 which are welded to a plurality of overlying line wires 14, and to two lengths of barbed tape 16 and 18, which are parallel to the line wires 14.

The lengths of barbed tape 16 and 18 are welded to one longitudinal edge of the fencing material. The fencing material is elongate and extends in the direction of the line wires for a length which is suitable to handle. The width of the fencing material is determined by the lengths of the cross wires 12 and, again, these lengths are fixed according to requirement.

The overlying wires and barbed tape are welded to the cross wires by means of welds 20 produced by a resistance welding technique which is p 1 Page 5 known per se.

Figure 2 illustrates in plan and schematically an installation 22 for producing the fencing material 10 shown in Figure 1. A substantial portion of the arrangement shown in Figure 2 is conventional and therefore is not described in detail. Those factors which are, however, necessary for an understanding of the present invention are elaborated on.

The arrangement 22 includes a welding bed 24 which has two platens which are movable vertically apart and which carry a plurality of mating welding heads 26. A feeding device 28, alongside the welding bed, is adapted to feed a cross wire 30 transversely into the welding bed when the platens are apart, in a step motion. A cutting device, not shown, is provided to sever the cross wire into relatively short lengths, equal to the width of the finished mesh.

Displaced laterally from the welding bed are a plurality of coils 32 of line wires 34. The line wires pass through a step feed mechanism 36 which operates in unison with the cross wire feeding device 28 and which is adapted to grip the line wires 34 and feed them, in successive steps, towards the welding bed. The line wires 34 of Figure 2 form the line wires 14 of the finished mesh shown in Figure 1.

Page 6 A barbed tape manufacturing machine 38 is positioned adjacent the coils 32. This machine produces barbed tape, using any suitable technique, and the emerging barbed tape, designated 40, is fed through a plurality of rollers 42 and then to the step feeding mechanism 36.

Figure 3 illustrates the barbed tape 40, and the rollers 42, in enlarged detail. The barbed tape 40 in this instance includes a core wire 44 around which is crimped a length of galvanized tape 46 which is pre- punched with barb formations 48. The rollers 42 are oriented so that they ride on the f lat surfaces of the barbs 48 and thereby ensure that the barbs lie in the plane in which the line wires 34 lie. This is in fact the plane of the fencing material which is fabricated in the arrangement 22 of Figure 2. This makes it possible for the core wire 44 to be brought into direct contact with and hence to be welded directly to, the individual cross wires 12, as is shown in the cross sectional view of the mesh in Figure 4.

The line wires 34 and the barbed tape 40 are advanced in step fashion by the feed mechanism 36 through the welding bed 24. With each stepped movement of the feed mechanism 36 the cross wire feeding device 28 feeds a cross wire 30 across the bed so that it overlies the line wires and the barbed tape, with the points of intersection of these wires being positioned below respective welding heads 26. The platens of the welding bed are closed so that the overlying wires of barbed tape and the line c Page 7 wires are resistance welded to the cross wire. Thereafter the cross wire 30 is severed from the welded cross wire, the platens are opened and fresh wire feeding takes place to repeat the aforementioned process. In this way a welded mesh 50 is formed from the overlying cross and line wires and barbed tape, and this emerges from the welding bed 24.

In the arrangement shown in Figure 2, a single length 40 of barbed tape is formed along one longitudinal edge of the mesh 50. It is apparent that by replacing any line wire with a mechanism which feeds barbed tape in place of the line wire, the number of lengths of barbed tape, incorporated in the mesh 50, can be varied according to requirement. For example, as has been pointed out, lengths of barbed tape may be positioned at intermediate locations in the mesh, or at each of the longitudinal edges of the mesh, or, in fact, it is possible to replace all of the line wires by lengths of barbed tape. When a large number of lengths of barbed tape are incorporated in the mesh, then it is preferably to feed the lengths of barbed tape from coils to the welding bed rather than from individual barbed tape machines.

It is apparent that if desired the machine 38 and the feeding device 28 can be interchanged so that the cross wires are formed by lengths of barbed tape.

Page 8 Although it is not essential it is preferred, from the functional and aesthetic points of view, that the core wires 44 are directly welded to the cross wires 12. Barbed tape known to the applicant has a core wire with a hardness of about 1500 mPa. This makes the tape difficult-to cut, but it is also difficult to weld using resistance welding techniques. Mild steel wire on the other hand, with a hardness in the region of 450 mPa, is easily welded, but is also easily cut. The applicant has found through experiment that a suitable compromise is to use low carbon high tensile core wires with a hardness of from 800 to 900 mPa. This confers reasonable resistance to cutting, and so maintains the different effect of the fence, but is still weldable. This core wire is more easily handled than a conventional core wire and it is easier to ensure that the barbs are correctly oriented, relatively to the plane of the mesh 50, and so do not interfere with the resistance welding process.

The mesh 50 is produced in convenient lengths which can be handled, and is used for constructing a fence, in the normal way, by attaching the mesh to fence supports. The mesh size can also vary according to requirement, depending on the required deterrent effect of the mesh. In a security fence of a pref erred form of construction two or three horizontal lengths of barbed tape were provided spaced from each other along an upper edge of the mesh. The horizontal wires, and the barbed tape, were spaced at 150 mm intervals. The vertical or cross wires were positioned Page 9 at centres of from 50 mm to 100 mm. The height of the mesh was 2,4 metres.

Figure 5 shows a different embodiment of the invention in which the core wire of the barbed tape is dispensed with and use is made of planar galvanized barbed tape strips designated 60 which are parallel to one another at a spacing 62 which is substantially equal to the spacing 64 between parallel plain line wires 66.

The strips 60 are preferably preformed and coiled and these coils are used in an arrangement similar to that shown in Figure 2, in place of selected coils 32 from which emerge the line wires 66, marked 34 in Figure 2. The barbed tape machine 38 is thus dispensed with. The lengths of planar barbed tape, without core wires, and plain line wires 66 are then welded at intersecting points 68 to successive cross wires 70 at spaced intervals, substantially in the manner described in connection with Figure 2.

The lengths of barbed tape 60 are readily kept planar and the problem of orienting the core wires so that they can be welded to the cross wires, as shown in Figure 4, is eliminated.

The lengths of barbed tape 60 are relatively broad and are made from Page 10 material which is sufficiently thick to ensure that the tape strips are strong enough to form adequate replacements, from the strength point of view, for the plain wires in the welded mesh which are omitted.

The construction of Figure 5 is cheaper and more easily made than the arrangement of Figure 1. It is also easier to use a plurality of planar barbed tape strips at various locations in welded mesh type fencing material than a plurality of barbed tape lengths which include core wires. The strips 60 are highly visible and so are effective as visual deterrents.

The essence of the invention, in either of the embodiments described hereinbefore, lies in its ability to upgrade the deterrent effect of a welded mesh fence, under factory conditions, without producing an unsightly or dangerous mesh. Conventionally welded mesh fences are upgraded by the on-site addition of coils or lengths of barbed tape, barbed wire, or the like. This is time consuming and labour intensive, and can result in an unsightly fence. The barbed tapes normally positioned at the upper edge of the mesh, do not present a danger to passers-by, but do present an obstacle to a person attempting to scale the mesh. The mesh can also be handled with relative ease. These benefits are to be contrasted with the negative aspects of the diamond-mesh-type barbed tape fence described in the applicant's pending U.S.A. patent application No.588608 which, although having a maximum deterrent effect, is difficult to handle, can be Page 11 unsightly, and can present a danger to innocent people, or animals, coming into contact with the fence.

Page 12

Claims (14)

1. Fencing material which includes a plurality of overlying wires which are welded to one another to form a mesh, and at least one length of barbed tape which is welded to transverse wires in the mesh.

2. Fencing material according to claim 1 wherein the length of barbed tape is elongate and extends in the longitudinal direction of the mesh.

3. Fencing material according to claim 1 or 2 wherein the length of barbed tape is substantially parallel to plain wires which are welded to the transverse wires.

4. Fencing material according to claim 1, 2 or 3 wherein the barbed tape includes a core wire and the barbed tape is oriented so that the core wire is brought into contact with and is welded directly to the respective transverse wires.

5. Fencing material according to claim 4 wherein-the core wire has a hardness of from 800 to 900 mPa.

Page 13

6. Fencing material according to claim 1, 2 or 3 wherein the barbed tape comprises a planar strip of material with barbed formations which is welded directly to the respective transverse wires.

7. Fencing material according to any one of claims 1 to 6 wherein at least one length of the barbed tape is located along at least one longitudinal edge of the mesh.

8. Fencing material which comprises a plurality of overlying plain wires which are welded to one another to form an elongate mesh and at least one elongate length of barbed tape located along at least one longitudinal edge of the mesh.

9. Fencing material according to claim 8 wherein the barbed tape includes a core wire which is brought into contact with, and which is welded directly to, respective transverse wires in the mesh.

10. Fencing material according to claim 8 wherein the barbed tape comprises a planar strip of material with barbed formations which is welded directly to respective transverse wires in the mesh.

11. A method of making fencing material which includes the steps of feeding at least one length of barbed tape and a plurality of Page 14 lengths of wires, all of which are parallel to and spaced from one another, through a welding station in steps, and, for each step movement, at the welding station, welding a transverse wire to the barbed tape and to each of the lengths of wires.

12. A method according to claim 11 which includes the step of drawing the barbed tape directly from a machine which is used to manufacture the barbed tape and orienting the barbed tape so that a core wire is welded directly to each of the respective transverse wires.

13. Fencing material substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

14. A method of making fencing material substantially as hereinbefore described.