BACKGROUND

The present invention relates to a barb tape. More particularly, the invention relates to a barb tape including a pair of parallel wires.

Barb tapes are known. For instance, US4,509,726 "Barrier", US5, 109,583 "Method of manufacturing barbed tape", US5,401 ,002 "Barb stiffening process and product" and ZA99/2967 "Barb tape" describe a barb tape comprising a strip material and a single wire, wherein the wire extends axially along the strip material and is crimped thereby.

A drawback of known barb tape is that they are not easily welded to each other to form a panel - only two relatively narrow strips of barb tape extending from the axially extending wire may be used to spot weld overlapping transverse barb tapes to each other.

It is an object of the present invention to address this drawback.

SUMMARY OF THE INVENTION

According to a preferred embodiment of a first aspect of the present invention there is provided a barb tape that includes: a first wire; a second wire that is spaced from, and extends substantially parallel to the first wire; an elongate strip material defining: a spine; and a plurality of barbs extending from at least one major edge of the spine, wherein the spine crimps the first and second wires. Preferably, the spine is substantially planar.

Typically, the major edges of the spine are substantially parallel.

Generally, the first and second wires are spaced a distance more than half the width of the spine.

Preferably, the first and second wires are spaced between 10mm and 20mm.

Optionally, the first and second wires are crimped along the major edges of the spine. Alternatively, the spine defines: (i) a first flange that extends laterally from the first wire, away from the second wire; and (ii) a second flange that extends laterally from the second wire, away from the first wire.

Typically, the first flange defined by the spine, the second flange defined by the spine, and the spine portion extending between the first and second wires lie substantially in the same plane.

The first and second flanges defined by the spine may be between 2mm and 5mm in width. Generally, the first and second wires are arranged symmetrically about the longitudinal axis of the strip material.

Preferably, a plurality of barbs extend from both major edges of the spine. Typically, the barbs comprise sets of opposing pairs of barbs that share a common shaft that extends laterally from the spine.

Generally: (i) the shafts of adjacent sets of barbs along a first major edge of the spine are spaced less than 85mm apart; and (ii) the shafts of adjacent sets of barbs along a second major edge of the spine are spaced less than 85mm apart. Preferably, the shafts of the barbs along the first major edge of the spine are aligned with the shafts of the barbs along the second major edge.

Typically, the sets of barbs are substantially equi-spaced along the spine.

According to a preferred embodiment of a second aspect of the present invention, a barb tape panel comprising at least two barb tapes according to the first aspect of the invention that are: (i) oriented transverse to each other; and (ii) welded, riveted, stapled, hog-ringed, clipped, adhered or crimped to each other at points of intersection in the region of the spine between the first and second wires.

BRIEF DESCRIPTION OF THE DRAWINGS

The aspects of the invention will now be described in more detail, by way of examples only, with reference to the accompanying drawings in which:

Figure 1 is a top perspective view of a barb tape according to a preferred embodiment of a first aspect of the invention;

Figure 2 is a bottom perspective view of the barb tape in Figure 1 ;

Figure 3 is a bottom perspective view of a barb tape according to an alternative embodiment of the first aspect of the invention; and

Figure 4 is a plan view of a welded barb tape panel according to a second aspect of the invention comprising barb tapes in Figure 1 welded to each other.

In this specification, "wire" means an elongate metal body that is formed by drawing, cutting, rolling or stamping.

DESCRIPTION OF THE INVENTION With reference to Figures 1 and 2, according to a preferred embodiment of a first aspect of the invention a barb tape 10 includes an elongate strip material 12, a first wire 14 and a second wire 16. The elongate strip material 12 comprises a substantially planar spine 18 that extends axially along the elongate strip material 12. The spine 18 is between 20mm and 50mm in width, defining substantially parallel major edges 20 (i.e. the major edges of the spine 18 are angularly offset from parallel by no more than 5 degrees) and, although the spine 18 has been shown with linear major edges 20, these edges 20 may undulate along the length of the spine 18. Preferably, the spine 18 is either 12.2mm or 18.8mm in width (i.e. the major edges of the spine 18 are spaced 12.2mm or 18.8mm). The spine 18 may be of any length (typically more than 200mm), is made of a steel sheet that is between 1 mm and 3mm in thickness. It will be appreciated that, although the spine 18 has been described as being substantially planar, the spine 18 in axial cross section could alternatively be V-shaped.

The elongate strip material 12 also defines a plurality of barbs 22 that terminate in a sharp point. The barbs 22 extend from both major edges 20 of the spine 18 and are arranged in sets of opposing pairs of barbs 20 that share a common shaft 24 that extends laterally from the spine 18. Figures 1 and 2 show each pair of barbs 22 extending from the free end of the shaft 24 in a direction substantially parallel to the axis of the spine 18. The pointed end of each barb 12 is laterally spaced between 5mm and 8mm from the major edge 20 of the spine 18, and the opposed pointed ends of each set of barbs 22 are spaced between 25mm and 35mm from each other. Furthermore, adjacent shafts 24 along the same major edge 20 of the spine 18 are spaced between 40mm and 85mm, preferably 50mm. In other words, the centreline of adjacent shafts 24 are spaced between 40mm and 85mm, preferably 50mm. The shafts 24 and barbs 22 are arranged symmetrically about the longitudinal axis of the strip material 12, i.e. the shafts 24 and barbs 22 along a first major edge 20 of the spine 18 are aligned with the shafts 24 and barbs 22 along the second major edge 20 of the spine 18. And, the shafts 24 / sets of barbs 22 are substantially equi-spaced along the spine 18.

The first and second wires 14 and 16, which are made of high tensile steel, are spaced from, and extend substantially parallel to each other. Figures 1 and 2 show the wires 14 and 16 crimped by the elongate strip material 12 along the major edges 20 of the spine 18. Although the barb tape 10 has been described as including only first and second wires 14 and 16, it will be appreciated that the barb tape could include additional third and fourth wires, in which instance the width of the spine 18 will likely exceed 18.8mm in width). Figure 3 shows an alternative embodiment of the barb tape 1 10. This alternative embodiment is similar to the first embodiment of the barb tape 10, however, whereas the wires 14 and 16 in the first embodiment are crimped to the elongate strip material 12 along the major edges 20 of the spine 18, the wires 1 14 and 1 16 in the alternative embodiment are crimped by the elongate strip material 1 12 inwards of the major edges 120 of the spine 1 18. Preferably, the wires 1 14 and 1 16 are arranged symmetrically about the longitudinal axis of the elongate strip material 12 and are spaced from each other a distance more than half the width of the spine 1 18. In this alternative arrangement, the spine 1 18 defines: (i) a first flange 1 17 that extends between 2mm and 5mm laterally from the first wire 1 14, away from the second wire 1 16; and (ii) a second flange 1 19 that extends between 2mm and 5mm laterally from the second wire 1 16, away from the first wire 1 14. In other words, each of the first and second flanges 1 17 and 1 19 are between 2mm and 5mm in width. Since the spine 1 18 is generally planar, the first flange 1 17, the second flange 1 19, and the spine 1 18 portion extending between the first and second wires 1 14 and 1 16 lie substantially in the same plane.

A barb tape panel 230 according to a second aspect of the invention is made using barb tape 10 according to the preferred embodiment of the first aspect of the invention. It will be appreciated that the barb tape panel 230 may alternatively be made using barb tape 1 10 according to the alternative embodiment 1 10 of the first aspect of the invention.

The barb tape panel 230 comprises a first array of parallel barb tapes 10 and a second array of parallel barb tapes 10, which second array of parallel barb tapes 10 are angularly offset relative to, and overlap the first array of parallel barb tapes 10, defining points of intersection between barb tapes 10 in the first array and barb tapes 10 in the second array. The barb tapes 10 are welded to each other at their points of intersection in the region of the spine 18 between the first and second core wires 14 and 16. Such welded portion could extend to (and include) the wires 14 and 16. It will also be appreciated that as an alternative to welding the barb tapes 10 to each other at their points of intersection, the barb tapes 10 could be riveted, stapled, hog-ringed, clipped, adhered or crimped to each other.

It will be appreciated that since the core wires 14 and 16 are disposed along the major edges 20 of the spine 18, the spine 18 provides a relative wide planar, unbroken region between the wires 14 and 16 to facilitate spot welding. In contrast, should a wire 14 or 16 be arranged along the axis of the spine 18 (as per prior art barb tapes), it will be appreciated that the wire 14 or 16 would break the planar region of the spine into two, providing two relatively narrow regions (instead of a relative wide, singe region) for welding.

Furthermore, by incorporating a second wire 16 and 1 16: the rigidity of the barb tape 10 and 1 10 is increased; the resistance of the barb tape 10 and 1 10 to being cut is increased; the barb tape 10 and 1 10 appears to be more bulky, increasing the visual deterrence of the barb tape 10 and 1 10; the barb tape 10 and 1 10 is less susceptible to bending and deformation during installation and handling / forming of a barb tape panel 230; the diameter of the wires 14, 1 14, 16, 1 16 may be decreased (while maintaining the same strength as a barb tape with a single wire); and the thickness of the elongate strip material 12 and 1 12 may be reduced (while maintaining the same strength as a barb tape with a single wire). By enabling a decrease in the thickness of the elongate strip material 12 and 1 12, the sharpness of the barbs 22 and 122 may thereby be increased.