Barbed strip

The present invention relates to a barbed strip for use in forming defence barriers and fences and so on.

, Known barbed strip consists of high-grade sheet steel which imparts sufficient strength against unwanted deformation to its very long and slender barb tips and, in addition, is free of corrosion. The barbs of this strip, which are situated opposite one another in pairs without staggering at both sides of the strip, project laterally with plane surfaces from the strip, which in turn is substantially semicircularly curved in cross-section and which may be coiled ready for use, triangular notches being provided in lateral regions of the strip adjacent to the strip longitudinal edges to facilitate the coiling.

Such barbed strips admittedly have a particularly satisfactory protective or blocking action when used as barriers because of their long barb tips, but the strips are uncommonly expensive to produce because they are not only high in material costs for their high-quality material but also high in manufacturing costs. This arises because the high-strength material required for stabilizing the barb tips presents considerable problems in cutting out or stamping the barbs, and in shaping and coiling the strip.

Therefore, barbed strips such as are known from German Patent Specifications 1,033»626 and 1,040,940 for example ¹ 25 are still most often used. These strips consist of unalloyed sheet steel, which may be galvanized to protect it against corrosion, and which offers a considerably lower strength and rigidity. Accordingly, the barbed strip has a spring steel wire as a core, which is more or less surrounded by the sheet metal, while the marginal edge portions of the sheet metal, which do not surround the spring steel wire, are used to form the barbs. These barbs have only very short, free barb tips formed by perforating the sheet metal with parallel rows of holes and cutting the sheet metal into strips along the rows of holes with a zig-zag sequence of cuts, each tangent to two successive holes. The . blocking action of barriers of barbed strips formed in this fashion is considerably less and to some extent inadequate, but the production of such barbed strips is considerably more economical because of the cheaper sheet material which is also much easier to work.

It is the object of the present invention to provide an improved barbed strip which is relatively cheap and simple to manufacture.

According to the present invention barbed strip is composed of unalloyed sheet steel forming also the barbs of the strip, the barbs each having a basic slender, substantially triangular shape presenting two barb tips at two corners of the triangle respectively, two side edges of each barb merging into a connecting portion of the barb, connecting the barb with the strip proper, close to an imaginary third corner of the triangle lying in the connecting portion, each barb having at least one corrugation which stiffens its barb tips.

Barbed strip in accordance with the present invention, while using relatively cheap and easily worked unalloyed sheet steel which gives rise to only a fraction of the production costs and machining expenses associated with similar operations on high-grade sheet steel, provides a blocking action when used as a barrier which is at least equal to that of barbed strips composed of high-grade sheet steel, while the corrugations of the barbs imparts a stability to the barb tips which exceeds that of the barb tips of barbed strip hitherto manufactured from high-grade steel which ensures that these cannot easily be bent into .10 an ineffective position.

The corrugations in the barbs can be provided before cutting or stamping the sheet metal, or afterwards, by stamping or rolling the barbs. In the latter case preferably a single corrugation is provided in each barb extending in the direction of the longitudinal axis of the strip.

The corrugations not only stiffen but may act to sharpen the barb tips and at the same time strengthen the barb as a whole. The blocking action of the strip can be increased when used as a barrier by bending the barb tips and/or the barbs at an angle to the longitudinal axis of the strip. Various configurations are possible to present the barb tips in different directions in space when the coiled strip is used to form a barrier, such that the spatial blocking action of the strip and each coil thereof is increased and the risk for persons who try to penetrate through the barrier.

The barbs may be staggered in relation to one another

- ל along the length of the strip or they may be arranged In pairs on opposite sides of the strip without stagger.

Barbs may be provided along one side only of the strip.

In this case it is preferred that the barb tips be set at ל a fairly large angle in relation to the longitudinal axis of the strip. Such setting can be brought about not only by bending the barb tips themselves but also by setting the angle of the whole barb by twisting its connecting portion with the strip proper.

Barbed strips in accordance with the present invention are preferably used in a coiled configuration having its adjacent turns clipped together at opposite sides. Instead of this known configuration, however, the strip may be laid in any other suitable form for example straight.

Preferably, the strip is beaded, the sheet steel being wrapped partially round a spring steel wire which extends lengthwise of the strip. The wire stabilizes the shape of the strip and provides greater opposition to cutting the strip. Also, when the strip is to be laid in a coil the wire increases the restoring capacity of the strip to the parting of its turns and encourages oscillations of the strip coil when the coil is touched.

Specific embodiments of the present invention will now be described by way of example with reference to the accompanying drawings in which:

Figure 1 is a plan view of a lengthwise portion of barbed strip according to the present invention showing three different formations of barbs disposed in pairs, on

- ⁶־' .

opposite sides of the strip.

Figure 2 is a side view of Figure 1, and Figures 3, 4 and ל are sections on lines III-III, IV-IV and V-V respectively in Figure 1.

ל With reference to the accompanying drawings, the barbed strip consists of mild steel sheet which may be galvanized. The sheet material is about 0.ל mm in thickness. Figure 1 shows a lengthwise portion 1 of the strip which is produced flat and then beaded round a spring steel wire 2.

The barbs 3♦ 4 or 6 ,ל or 7, 8 are formed integrally with the strip and disposed, with spacing, one after the other along the length of the strip, the barbs projecting laterally from the strip 1 on opposite sides.

Regardless of their final shape and alignment

1ל illustrated in the drawings, the barbs consist, in their basic shape, of very slender isosceles triangles which are bounded by an outside, at least initially longitudinally directed base edge 9 of comparatively great length, for example, more than ל cm, and by side edges 10. The side edges 10 form very small acute base angles with the base edges 9, for exainple less than 2⁰ל, and preferably about 10°, and merge, close to their imaginary point of intersection with one another into a connecting portion 11 in the form of a short connecting web of the sheet metal.

2ל The base edges 9 of the barbs 3 to 8 form a small acute angle with the longitudinal centre line of the strip 1, which angle is produced by a slight deformation of the connecting portions 11. The barbs as shown are situated at each side of the strip 1, opposite one another in pairs without staggering but the barbs at opposite sides of the strip portion may be staggered in relation to one another in the longitudinal direction of the strip if desired.

The barbs are all provided with corrugations which stiffen the barb tips and which at the same time also increase the shape stability of the barbs as a whole. The barbs 3, 4 each have two corrugations 12, each of which extends along a side edge 10 of the barbs which forms the outer boundary edge of the corrugation. The barbs 5, 6 have single corrugations 13 extending parallel to and close beside their base edges 9» while the barbs 7_t 8 have single corrugations 14 which extend parallel to and along their base edges 9. The corrugations 13, 14 extend lengthwise of the strip before final setting of the barbs and are formed by conveying the barbs continuously between pairs of rollers, whereas the corrugations 12 are formed by a stamping operation between stamping dies.

The barb tips 3’ and 4’ of the barbs 3> 4 are correspondingly bent to one side of their barb, the corresponding tips of the two barbs being oppositely bent and the direction of bending of the barbs alternating as between adjacent barbs along each side of the strip portion.

The barb tips 7’ and 8’ are oppositely bent out of 25 the general plane of their barbs, the corresponding tips of the two barbs being oppositely bent and the direction of bending of adjacent barb tips along each-side of the י strip portion also alternating.

The barbs 5> 6 have the simplest alignment without any bending of their tips.

In addition to, or instead, the barbs 3, 4 or 5, 6 or 7, 8 as a whole may be set at an angle by twisting their connecting portions 11 as shown for example in relation to the barbs 5; 6 by the chain lines 5’, 6’ in Figure 2. The setting angle may be' selected as desired.

For laying to form an obstacle or blockage, the barbed strip according to the present invention may be helically coiled, its turns being clipped together alternately on opposite sides of the coil so as to stabilize the location of the turns when the coil is pulled apart.

This facilitates the laying of the strip to form a barrier and also the removal thereof when re-assembling the barrier into a coil.