Textiles: spinning – twisting – and twining – Reinforcing or tire cords
Reexamination Certificate
1999-01-05
2001-06-19
Calvert, John J. (Department: 3741)
Textiles: spinning, twisting, and twining
Reinforcing or tire cords
C057S212000, C057S213000, C057S214000, C057S218000, C057S231000, C057S237000
Reexamination Certificate
active
06247298
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a fabric for use as a stab-resistant insert in protective textiles such as clothing in general, vests in particular, sail cloths and canvasses.
The present invention also relates to a steel cord specially adapted for use as a reinforcement in such stab-resistant inserts, and more particularly to a multi-strand steel cord, i.e. a steel cord comprising two or more strands of a twisted structure with the strands being twisted with each other.
BACKGROUND OF THE INVENTION
On the one hand, steel cord constructions, in general, and multi-strand steel cord constructions, in particular, are widely known in the art, for example for the reinforcement of rubber tires, conveyor belts, hoses and timing belts.
Protective and bullet-proof clothing, on the other hand, is also widely known in the art. Bullet-proof clothing are commonly reinforced with high-tensile synthetic yarns such as aramide in order to obtain a sufficient bullet-resistance. Synthetic yarns have proved to provide for a sufficient bullet-resistance, but their resistance against stabs and knives has remained insufficient.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide for a fabric for use as a stab-resistant insert in protective textiles.
It is a second object of the present invention to provide for a steel cord which gives sufficient stab-resistance to bullet-proof textiles.
It is a further object of the present invention to provide for a steel cord construction with sufficient elongation to reinforce bullet-proof clothing.
It is another object of the present invention to provide for a steel cord construction which can be manufactured in an economical way.
It is still another object of the present invention to provide for a fabric and a steel cord steel cord construction with a sufficient degree of flexibility.
According to a first aspect of the present invention, there is provided for a fabric for use as a stab-resistant insert in protective textiles. The fabric comprises a plurality of steel cords and each of these steel cords comprises a longitudinal axis and two or more steel filaments. Each of these steel filaments form a twisting angle with the longitudinal axis of the steel cord. These steel cords have two or more, preferably three or more, of such twisting angles which are substantially different from each other.
The fabric can be a woven structure, a knitted structure or a knotted structure.
The fabric is preferably coated with an adhesive.
In case the fabric is a woven structure, the steel cords may form the warp, the weft or the warp and the weft. Non-metallic filaments may bind the warp with the weft.
According to a second aspect of the present invention, there is provided a steel cord comprising two or more strands of a twisted structure with the strands being twisted with each other. At least one of the strands consists of a first group and of a second group. The first group has at least one steel filament and has a first twist pitch, the second group at least two steel filaments and has a second twist pitch. The first twist pitch is substantially different from the second twist pitch. The first group forms together with the second group the strand. At least one of the other strands comprises filaments which are twisted with each other with a third twist pitch which is different from the first twist pitch and which is different from the second twist pitch.
The advantage of the above-mentioned fabric and of the above-mentioned steel cord construction can be explained as follows.
Steel filaments provide an improved resistance against stabs in comparison with synthetic yarns. The greater the filament diameter the greater the stab-resistance. Thick filaments, however, lead to a lack of flexibility.
It has now been discovered that the stab-resistance of a steel filament is at the smallest when the angle between the stab and the filament is a right angle of 90° and that the stab-resistance becomes greater when the angle between the stab and the filament becomes oblique and more different from a right angle. Since it cannot be predicted from what angle of direction a stab will come, a steel cord construction having different twisting angles is suitable for providing the necessary stab-resistance while providing at the same time the required degree of flexibility.
The steel cord for use as a reinforcement of a fabric according to the first aspect of the present invention has at least two, preferably at least three substantially different twist pitches in order to provide for at least three different twisting angles.
Preferably, the filaments which have the substantially different twisting angles appear at least partially at the surface of the steel cord.
The steel cord according to the second aspect of the present invention has three substantially different twisting angles and further comprises at least one strand consisting of a first group and a second group. Such a strand can be designated as an (m+n)-strand. An (m+n)-strand already comprises two different twist pitches (or twisting angles) and can be made in one single step, as has been disclosed in U.S. Pat. No. 4,408,444, which makes it particularly suitable for use as reinforcement of stab-resistant inserts. Further twisting such an (m+n)-strand with another strand may provide for a steel cord which can be made in only two manufacturing steps and which comprises three different twisting angles.
Examples of such an (m+n)-strand are:
2×0.18+2×0.18 twist pitches ∞/8 mm
3×0.15+2×0.15 twist pitches ∞/10 mm
3×0.12+3×0.12 twist pitches ∞/10 mm
3×0.12+2×0.15 twist pitches ∞/10 mm
(1 copper wire and two steel wires of 0.12 mm)+2×0.15 twist pitches ∞/10 mm
The filament diameters of the invention steel cord range from 0.05 mm to 0.45 mm, the lower limit being dictated by reasons of cost and by reasons of sufficient stab-resistance, the higher limit being dictated by reasons of flexibility.
Since a high tensile strength is not the first requirement to be met by the invention steel cord, the steel filaments may also be made of a stainless steel instead of a more common carbon steel. Also combining of both steel wires and stainless steel wires are possible. Including of a copper wire for shaping the fabric is not excluded. Indeed, the effect of cutting depends upon the material of the wires used: copper wires are cut differently from plain carbon steel wires, plain carbon steel wires are cut differently from stainless steel wires.
In a preferable embodiment of the present invention, all the twisting occurs in the same direction (S or Z), which gives to the total steel cord a higher elongation, and, as a consequence, a higher degree of flexibility and a higher demping potential.
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Research Disclosure, No. 319, pp. 868-871, Nov. 1990.
Bourgois Luc
Bruyneel Pol
Van Giel Frans
Vanassche Roger
Calvert John J.
Foley & Lardner
Hueley Shaun R.
N.V. Bekaert S.A.
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