FR2465186A1 - Reinforcement for ballistic screen - has very hard granules of mineral origin tightly packed in resin layer on surface of screen - Google Patents

Abstract

The method of reinforcement uses a layer of reinforcement using very hard granules (13) and a joining layer. The granules are polyhedral, drawn from incompressible material, pref. of mineral. The granules are of a crystalline structure such as quartz chalcedony. The granules are graded to make them roughly the same size and these are partly held in a resin layer. A double facing or granules can be covered with one or more layers of inert material such as glass fibres, fixed by resin.

Description

 The ifpion relates, in general, to a process for the reinforcement of ballistic protection screens, used to stop projectiles, notably firearms.

 The invention relates more specifically to the shielding of bodies, envelopes, protective screens and in particular the shielding of so-called thin sheets, such as those used: in the civil industry for lining doors or making automobile bodies.

 In the French patent No. 79.16414, in the name of the applicant, a ballistic screen structure has been described making it possible to achieve armor-proof bulletproof, low weight, low thickness, ensuring a strong guarantee of protection, in particular against the firing of civil weapons, known as of free sale.

 In this application, various examples of the execution of such screens have been highlighted, and the performance of these screens subjected to shooting tests has been given, either by so-called hunting cartridges or by bullets.

In all the test cases, the screens played their full protective function, without having been crossed by the projectiles.

By pushing the tests more fully, we tested projectiles of the 22 long rifle type, said to have high velocity, more efficient than those used during the tests designated in the previous application.

 With such projectiles, satisfactory results have still been obtained, but weaknesses which do not make it possible to guarantee 100% non-crossing of the projectiles.

 The present invention therefore aims to provide an additional guarantee of protection without increasing the thinness of the first screens, and without appreciable increase in weight.

Another object of the invention is to provide a stop screen, fired impact impact, ensuring the destructuring of firing projectiles by crushing, deformation, development, considerably reducing the power of penetration.

Yet another object is to create a stop screen forming a heat shield, in order to neutralize the perforations by melting effect on the constituent materials of the screen.

 To meet these aims, the invention relates more specifically to a method for reinforcing ballistic protective screens, used to stop firing projectiles, a method characterized in that the reinforcing layer is partially developed using of a very hard aggregate, and of a binder, and this granulate is given the form of polyhedra 9 sharp angles, drawn from an incompressible material, preferably of mineral origin, and in that one associates this aggregate with at least one support layer.

 According to one arrangement, the granulate is preferably selected from a hard mineral, with a crystalline structure, such as chalcedony quartz.

According to another arrangement, the mineral reinforcing layer is coated on both sides with one or more layers of inert material, such as woven or non-woven glass fibers, to form a laminate for holding the coated aggregate.
The invention is therefore based on the properties known per se, of certain minerals which have hardness characteristics much higher than those of projectiles, as evidenced by the firing tests carried out on massive mineral blocks, with crystalline structure, such as quartz. chalcedony. We note that under the impact of a projectile, these blocks are never started, the projectiles are most often deviated from their course by ricochet, and very strongly deformed.

 It goes without saying that such blocks owe their property to their hardness, but also to their mass which strikes without appreciable plastic deformation. It is understood that such blocks are unusable in the state, in particular because of their weight for the constitution of a ballistic screen.

In an arrangement in accordance with the invention, it was possible to retain the initial hardness properties of the mineral matter, thanks firstly to a fragmentation calibrated to form a relatively thin impact layer, associated with at least one layer shock wave absorption support, thanks to which the naturally breaking character of the impact layer is neutralized but moreover, this fragmentation of the mineral matter in the form of polyhedrons with sharp angles has the effect of destructuring by slicing, tearing, followed by deformation by blooming, the material of the projectile, mass and envelope.

 Surprisingly, the projectile is stopped by such a screen; it appears after impact in the form of a thin patch, with fairly irregular contours, with very crushed inclusion of the envelope.

Other characteristics will appear further in the detailed description which follows, of various embodiments of the invention, of which here under dwesexeples, and illustrated in the accompanying drawings in which
Figure 1 is a schematic sectional view showing the components of the reinforcing layer of a ballistic screen.

 Figure 2 is a schematic sectional view showing a reinforced ballistic screen.

Figure 3 is a view similar to Figure 2 showing the action of the reinforcing layer on a projectile,
Figure 3 is a view showing an alternative embodiment of a reinforced ballistic screen.

 As shown in FIG. 1, the process for reinforcing ballistic protective screens consists in developing a reinforcing layer: t, which has been designated as a whole, by the general reference 10.

 This reinforcement layer essentially comprises two parts, a stop layer 11, and a support layer 12.

The barrier layer i1 is formed from an aggregate of which the grains 13 are constituted by polyhedra with sharp angles of very great hardness, drawn from an incompressible material, of mineral origin, in particular chalcedony quartz,
The aggregates 13 of the barrier layer are coated, at least partially in a coating resin 14.

 The aggregates of the barrier layer are calibrated to obtain fragments of substantially identical dimensions which are arranged, as shown in FIG. 1, in the joined state so as not to leave any vacuum remaining on the surface of this aggregate bed.

 The coating bed 14 is linked to the backing layer 12, which may advantageously consist of a laminate formed of several layers comprising long reinforcing fibers woven or else, such as a roving of glass fibers, or a glass mat. It goes without saying that the nature of the components of the laminate and the mode of organization of the layers can be varied within wide limits, depending on the constraints and the power of the shock waves, which must be neutralized by the layer. reinforcement. For example, one can design an extremely hard and rigid backing layer making a hit, in which case preferably layers of glass fibers will be used. In other conditions of use, a backing layer having a certain modulus of elasticity, in which case organic fibers of the aromatic polyamide type, called aramid with high tensile strength, will be used as reinforcement fibers.

 According to a preferred arrangement, as shown in FIG. 2, it is advantageous to completely coat the aggregate 13, in the resin 14, and to provide on the two faces of the barrier layer 11, a facing, respectively 15, 16 , which can be a roving or a glass fiber mat, bound to the coating resin. This structure has the advantage of guaranteeing good cohesion of the resin for coating the aggregate, when the latter is subjected to successive shock waves from the firing impacts. In this way, the breaking effect is neutralized in the barrier layer, and the cohesion of the aggregates is maintained, including in group fire actions. The aggregates of the barrier layer form, on the one hand a shield mechanical destructuring of firing projectiles, but also a heat shield which protects the constituents of the underlying strata of the support layer.

In FIG. 3, the behavior of a firing projectile 17, formed of a mass 18 and of an envelope 19, is diagrammatically shown, when it is subjected to the destructuring action of the barrier layer 11. When the projectile comes into contact with the aggregates of the barrier layer, it occurs first of all, several incipient tears in the casing 19, immediately followed by a development of the mass 18, which then appears, as shown in the drawing in the form of a thin patch, containing several times the initial diameter of the projectile before impact.

 It is remarkable to note that a reinforcement screen developed in accordance with the provisions of FIGS. 2 and 3, can be used alone, as a ballistic screen, without additional reinforcement element, which allows the constitution of thin screens, particularly easy to implement, in particular for the shielding of thin sheets, flat, yes curved.

 In certain fields of application, it is possible to profitably combine the reinforcement screens as described above, with the ballistic screens comprising on either side of a core of low density material, strata (b fibrous material , woven or not, linked in whole or in part to this core by a polyester resin.

An example of execution of such a complex is represented in FIG. 4, in which this complex associated with a thin plate 12, constitutes a shielding having a high safety coefficient, This complex is formed first of all on the impact side of shooting, immediately behind the sheet 20, and possibly at a certain distance from the latter, of the stop layer 11.

This barrier layer is followed by the support layer 12, which here comprises a balsa core 21. The balsa core is coated with a first layer formed in particular of a glass mat 22, and of a roving 23.

On the face opposite to the impact of the shot, the balsa friend 21 is coated with a glass mat 24, followed by a roving 25, the whole being bonded by a polyester resin.

As has been said above, it is advantageous to incorporate, as reinforcing fibers, into the laminate, organic fibers of the aromatic polyamide type, called aramid with high tensile strength.

Of course, the invention is not limited to the embodiments described above and shown, for which other variants can be provided, without thereby departing from the scope of the appended claims.

Claims (5)

1) Method for the reinforcement of ballistic screens of  protection, used to stop firing missiles, especially of weapons 9  fire, process characterized in that the reinforcing layer is produced  partly using a very hard aggregate and a binder, and we give to this aggregate the shape of polyhedra with sharp angles, drawn from a material  incompressible, preferably of mineral origin, and in that we associate  this aggregate has at least one layer of support. 2) Reinforcement method according to claim 1, characterized in that the granulate is preferably selected from a hard mineral å crystal structure such as chalcedony quartz. 3) A reinforcement method according to any one of claims 1 and 2, characterized in that the granulate is calibrated to obtain fragments of substantially identical dimensions, and forms a layer with contiguous grains which is at least partially bonded in a coating resin. 4) Reinforcement method according to any one of claims 1 to 3, characterized in that the mineral reinforcement layer is coated on both sides with one or more layers of inert material, such as woven or non-woven glass fibers. to form a containment laminate for the coated aggregate.  5) Reinforced ballistic screen with integrated mineral layer, according to any one of claims 1 to 4, characterized in that it comprises a stop layer formed of a flint aggregate with polyhedral grains, having one or more cutting edges. , and at least one support and shock wave absorption layer for this granulate, the layers of this laminate being bonded by a resin.