FR2607240A1 - Protection device for transporting or storing explosive charges - Google Patents

Abstract

The invention relates to a device allowing safe transportation or storage of explosive charges. According to the invention, the device essentially consists of a hollow body 2 which has an axis of symmetry 3 and the lower surface 4', 4'' of which opens out in the direction of its two open ends 6', 6'' from a central zone where the explosive charge is located. The effects of any explosion are thus essentially confined to the vicinity of the axis of symmetry 3. Application to light transports for primary explosives or suspect devices of various types.

Description

 The present invention barracks the transport and storage of explosive charges safely, the concept of transport having to be understood in a broad sense, since it may involve displacement of explosive charges during manufacturing operations in the workshop or storage ( for example with primary explosives used to initiate ammunition), as well as the movement and / or handling of a suspected device likely to explode.

 The field more particularly targeted is that of light transport, by means of portable devices by one or more people, as opposed to in situ, massive and bulky protection installations, in which handling arms are used.

 Beyond the known fixed installations comprising a wall which can be easily deconfigured to absorb part of the energy of the explosion (American patent NO 3 150 749 for example) or peripheral materials absorbing shock waves (European patent application NO 0 028 141 for example), many transportable devices have been developed.

 Mention may be made of French patent NO 2 513 221 describing an explosion containment enclosure, comprising a chamber delimited in a cylindrical envelope, and closed by reinforced end elements giving very high resistance to internal forces, thanks to a stiffening. important of these elements. However, such an enclosure is made from steel elements, welded to each other to form a very resistant structure, so that this enclosure is practically untransportable by human hand because of its weight.

 French patent NO 2 276 244 illustrates a device in which the deformability of a membrane is used, according to a principle often used in fixed installations. Here again, the explosive charge is entirely confined, and the structure is above all adapted to resist internal forces; moreover, this device is not easily transportable.

 Other devices for carrying light explosives have been developed. The cylindrical container described in French patent NO 2 437 988 is made of an olefin plastic, the molecules of which are oriented radially in the solid phase and not under tension, so as to be able to expand in the longitudinal direction without breaking: still uses the deformability of a closed structure to absorb part of the energy released during an explosion, which is interesting, but remains limited in terms of protection, in particular because nothing can affect the free propagation of shock wave when the closed container bursts. It is also necessary to cite the French patent NO 2 304 542, which describes a transportable set of closed cylindrical containers connected together by a strap to facilitate gripping.

 The state of the art can be further illustrated by the many types of containers intended to contain hazardous materials, the structure of which is more particularly adapted for on-site packaging (French patent NO 2 119 502 for example), or for shielding. composite of their wall (French patent NO 2 443 397 illustrates one example among others of interesting lamination, using a relatively rigid inner layer of plastic reinforced with fibers, and an outer layer of elastomer).

 Finally, mention should be made of the devices more particularly developed for damping noise, in combination with a shock wave generator, although these are generally not devices intended for transport. For example, French patent NO 2 295 399 describes such a device, comprising a container covering on all sides the charge of explosive, said container containing a fluid or gel at least partially vaporized by the energy emitted by the shock wave. , so as to affect the amplitude and frequency of the shock wave.

 The object of the invention is to propose a protection device which is both light in order to be transportable and make it possible to considerably attenuate the effects of an explosion.

 The object of the invention is also to produce a device the structure of which makes it possible to orient the breath of an explosion in a predetermined direction, while taking into account the fragments which can be simultaneously projected.

 Another object of the invention is to serve effectively as protection in the presence of a suspicious device liable to explode, for personnel called in emergency in such situations.

 It is more particularly a protective device for the transport or storage of explosive charges, characterized in that it is essentially constituted by a hollow body having an axis of symmetry, and the inner surface of which flares towards its two open ends from a central area where the explosive charge is placed, so that the effects of a possible explosion are essentially confined to the vicinity of said axis of symmetry.

 Preferably, the hollow body is of revolution about said axis of symmetry, then forming a body closed laterally and open only at its two ends.

However, it may prove to be advantageous to provide a curved body, not completely closed laterally, so that the expression "hollow body" used subsequently will have to be understood in a broad sense.

 Advantageously, the internal surface of the hollow body has a double curved profile whose curvature is turned towards the axis of symmetry, and is connected at the level of the central zone of the hollow body to form a constriction; in particular, the hollow body has a center of symmetry in the vicinity of which the explosive charge is placed.

 It is possible to adopt various shapes for the interior surface of the hollow body, but it is particularly advantageous to provide a generally parabolic or elliptical profile.

 Thus, for the first variant, the inner surface of the hollow body is essentially formed by two portions of paraboloid of revolution connecting at the level of the central zone of said hollow body, and the respective focus of which is disposed in the vicinity of the center of symmetry; for the other variant, the internal surface of the hollow body is essentially formed by two portions of ellipsold of revolution connecting at the level of the central zone of said hollow body and the respective focal point of which is located in the vicinity of the center of symmetry.

 In order to further lighten the structure, it is advantageous for the external surface of the hollow body to have a central constriction; in this case, the thickness of the hollow body is advantageously decreasing from the central throttle towards each of the ends.

 Preferably, the hollow body is made of a material which is both light and not very fragile and which offers good burst strength, in particular a material of the filament type: in particular, the hollow body may comprise crossed windings of filaments. , preferably reinforced, at least in the central zone of said hollow body, by circumferential windings, said windings being embedded in a synthetic resin.

 It is advantageous to provide that the device of the invention comprises a member for supporting the explosive charge disposed at a central throttle of the interior surface of the hollow body; in particular, the support member is a shoemaker provided with a closure cover, and said housing is supported by a transverse plate fixed to the interior wall of the hollow body, said plate preferably being produced in the form of a support disc with a central recess.

 Preferably, the hollow body is provided externally with gripping means, such as one or more handles fixed on the external surface of said hollow body.

 Other characteristics and advantages of the invention will appear more clearly in the light of the description which follows and of the appended drawing, relating to a preferred embodiment, with reference to the single figure of said drawing.

 The single figure is a view, partially in axial section (cutaway) and partially in elevation, of a device according to the invention.

 The device 1 illustrated represents a particularly advantageous embodiment for the safe transport of explosive charges.

 According to a fundamental aspect of the invention, this device is essentially constituted by a hollow body 2 having an axis of symmetry 3, and whose inner surface 4 ', 4 ", flares towards its two ends open from a central zone where the explosive charge is placed, so that the effects of a possible explosion are essentially confined to the vicinity of the axis of symmetry 3.

 The device 1 thus makes it possible to orient in a chosen direction the breath and, to a certain extent, the projections of an explosive device in its central zone and, thus, to considerably attenuate, even practically suppress, the effects of an explosion. in the other directions. Thus, the blast effect which manifests itself on both sides tends to gradually deviate from the axis of symmetry 3, while attenuating, which in itself represents a considerable advantage compared with known transport devices, including the structure was based on the principle of a completely closed containment.

 The hollow body 2 is here of revolution about the axis of symmetry 3, but one could very well envisage a curved hollow body, not completely closed laterally.

 However, a hollow body of revolution open only at its two ends, such as that illustrated here, has the advantage of not undergoing any impulse tending to move it violently during the explosion of the load to be transported.

 It should be noted that the splinters coming from an explosive charge or from a suspicious device placed in the center of the device of the invention are at least partly projected against the walls of the hollow body, and therefore notably braked, during thus part of their kinetic energy, unless of course they are planted in these walls to the extent that the material of the hollow body has been provided for this purpose.

 The orientation thus obtained for the shock wave, accompanied by braking or even by stopping any kinetic bursts represents considerable progress compared with existing devices.

 The inner surface of the hollow body 2 has a double curved profile whose curvature is turned towards the axis of symmetry 3. In the figure, there are thus distinguished the two inner surfaces 4 ′ and 4 ″ connecting at the level of the central zone of the hollow body 2 to form a constriction 5, the curvature of each curved profile always remaining facing the axis of symmetry 3, from said constriction 5 to the corresponding end openings 6 ', 6 ".

 The hollow body 2 advantageously has a center of symmetry 5 in the vicinity of which the explosive charge is placed.

 Various shapes can be adopted for the interior surface of the hollow body, but it is particularly advantageous to provide a generally parabolic or elliptical profile. Indeed, such profiles allow more effective confinement of the effects of a possible explosion in the vicinity of the axis of symmetry 3. This results from the well-known geometric properties of the parabola and the ellipse: if we assimilate the explosive charge at a point zone arranged at the focal point common to all the parabolas concerned, this results in a reflection of the breath produced by the explosion by the internal surface of the hollow body parallel to the axis of symmetry 3, or, for the ellipses in direction of the other focus, which is preferably relatively far from the emission center.

 In accordance with these two advantageous variants, the interior surface of the hollow body is essentially formed by two portions of paraboloid or ellipsoid of revolution connecting at the level of the central zone of said hollow body, and the respective focus of which is disposed in the vicinity of the center. of symmetry 7.

 In the single figure, the illustrated device comprises two portions 4 ′, 4 ″ of ellipsos of revolution, the end cap of which, shown in phantom, is removed at the level of the constriction 5. It will be observed that here the focus of each portion of the ellipse is merged with the center of symmetry 7 of the device. In practice, we will rather speak of a "focal zone" defined by a short inter-focus distance. It goes without saying that we will choose judiciously the parameters of each ellipse for the type of applications concerned, and in particular their eccentricity. The same would apply with paraboloids of revolution, for which the choice would however be limited to a single parameter.

 In order to further lighten the structure, it is advantageous that the external surface of the hollow body 2 has a central constriction, as illustrated here. However, it is preferable that the thickness of said hollow body is provided decreasing from this central constriction towards each of the ends. These provisions make it possible to contain, with a minimum weight, the explosion of the device placed in the center of the hollow body.

 Insofar as the explosive mass can be roughly assimilated to two points located at the focus of each parabola or ellipse, or to a single point, we see that the breath produced by the explosion is reflected by the interior surface of the hollow body parallel to 1 axis 3 (for portions of parabololdes of revolution), or substantially parallel to this axis (for portions of ellipsoldes of revolution) and towards the second focus (not shown), which is then provided relatively distant from the center of symmetry 7, which has the effect of confining the breath along said axis as has been explained above.

 The symmetry of the reflection phenomenon with respect to the median plane (plane of symmetry cutting perpendicularly the axis of the device in its center) makes it possible to ensure that the device does not undergo any impulse tending to move it violently during the explosion of the machine, insofar as this machine has a roughly cylindrical shape and where it has been placed approximately in the center and parallel to the axis of the device. Regarding the material of the hollow body, it is advisable to use a material not only light and offering a good bursting distance, but also not very brittle and absorbing energy well from impacts. particularly advantageous to use a material of the filament type, in the form of continuous filaments arranged by winding, or of fabrics produced in the form of sheets from filaments. Mention may be made, for example, of filaments of aramid, of glass, or of similar combinations, embedded in a synthetic resin, such as an epoxy or polyester resin. Optionally, an additional addition of sintered materials, for example ceramic, may be provided. However, it seems particularly advantageous to use filaments in crossed windings, reinforced, especially in the central zone of the device, by circumferential windings. The combination of these winding modes makes it possible to best ensure the resistance of the hollow body to the shock wave and radial impacts, in the center, and longitudinal, towards the open ends of said hollow body. The use of fibers from a material sold under the name "KEVLAR" gives excellent results. It goes without saying that it is also possible to combine different types of layer overlays, for example by providing crossed windings, reinforced in the central zone of the device, and associated fabrics for additional circumferential windings.

 In general, a person skilled in the art can easily choose from the many existing composite shields, but however preferring a light shield to preserve the easily transportable nature of the device.

 The explosive charge can be placed by any support means in the central zone of the device.

There is here a member for the support of an explosive charge 8.disposed at the level of the central throttle 5, said member in this case having the form of a shoemaker 9 provided with a key closure cover 12. This housing can be held relative to the hollow body 2 by a connection between its external lateral surface and the adjacent surface 20 of the constriction 5, and / or by means of a support plate fixed to the internal wall of the hollow body; such a plate is illustrated here in the form of a support disc 10 having a central recess 11. For the material of the shoemaker, of its cover, and of the possible support disc, use will be made of a cellular foam providing an anti- advantageous shards.

 It goes without saying that any other equivalent support means could be used in order to place the explosive charge in the vicinity of the center of the device. The safety transport device thus described can usefully be used for transporting sensitive explosive charges (such as those of primary explosives), in particular for manual transport given its relative lightness. In order to facilitate this transport, it will naturally be possible to provide the hollow body 2 externally with gripping means, such as one or more handles 13 fixed on the external surface of said hollow body. The handle 13 illustrated here is part of a set of several handles arranged peripherally in the upper portion of the device: this corresponds to an essentially vertical mode of transport. It goes without saying, however, that one could provide a single handle 13 arranged at the level of the central throttle of the hollow body, for a transport in which the axis 3 of the device would be essentially horizontal (in this case, we eliminate the risk of a possible reflection of the blast wave by the ground ).

 In any case, whatever the spatial arrangement of the device during its transport, the technical effect inherent in the interior surface of the hollow body remains unchanged.

 As an indication, a device of the type of that illustrated, having a relatively small dimensioning (36 cm in height and 25 cm in end diameter approximately), could be produced with a weight of the order of 4 kg, this which gives it great transportability.

 The device of the invention is also advantageous for the storage of explosive charges, especially with the workshop which transforms them, because it thus avoids the transmission of the detonation between the stored charges, without it being necessary to space them out. This produces an additional advantage, residing in the fact that the storage air can be reduced.

 The device of the invention can also serve as protection in the presence of a suspicious device. For such a use, the illustrated structure comprising a shoemaker and a closing cover is particularly suitable for centering and wedging the machine. After having introduced this machine into the case, then closing the cover, it suffices to orient the device in a direction compatible with the safety of the personnel.

 It appears from the foregoing description that the device of the invention makes it possible to obtain much lighter protection than with known fully closed devices, which are necessarily heavy by their structure, the latter having to make it possible to contain the explosion of the machine without risk of bursting the device itself.

 Finally, it should be noted that the use of relatively plastic filaments for the production of the hollow body is of particular importance, because, in the event of insufficient resistance, this material does not produce dangerous splinters, and does not break until after having absorbed some of the energy from the explosion.

 The invention is not limited to the embodiment which has just been described, but on the contrary encompasses any variant incorporating, with equivalent means, the essential characteristics appearing in the claims; tions.

Claims (14)

 1. Protective device for transporting or storing explosive charges, characterized in that it is essentially constituted by a hollow body (2) having an axis of symmetry (3), and whose inner surface (4 ', 4 ") flares towards its two open ends (6', 6") from a central area where the explosive charge (8) is placed, so that the effects of a possible explosion are essentially confined to the vicinity of said axis of symmetry.  2. Device according to claim 1, characterized in that the hollow body (2) is of revolution about said axis of symmetry (3).  3. Device according to claim 2, characterized in that the internal surface (4 ′, 4 ") of the hollow body (2) has a double curved profile whose curvature is turned towards the axis of symmetry (3), and connecting at the central zone of the hollow body to form a constriction (5).  4. Device according to one of claims 2 and 3, characterized in that the hollow body (2) has a center of symmetry (7) in the vicinity of which is placed the explosive charge (8).  5. Device according to claims 3 and 4, characterized in that the inner surface of the hollow body (2) is essentially formed by two portions of paraboloid of revolution connecting at the central zone of said hollow body, and whose focus respective is arranged in the vicinity of the center of symmetry (7).  6. Device according to claims 3 and 4, characterized in that the inner surface of the hollow body (2) is essentially formed by two portions of ellipsoIde of revolution connecting at the central area of said hollow body and whose focus respective concerned is arranged in the vicinity of the center of symmetry (7).  7. Device according to one of claims 2 to 6, characterized in that the outer surface of the hollow body (2) has a central constriction.  8. Device according to claim 7, characterized in that the thickness of the hollow body (2) decreases from the central throttle towards each of the ends.  9. Device according to one of claims 1 to 8, characterized in that which hollow body (2) is made of a material that is both light, not very fragile, and offering good resistance to bursting, in particular a material filamentary type.  10. Device according to claim 9, characterized in that the hollow body (2) comprises crossed windings of filaments, preferably reinforced, at least in the central zone of said hollow body, by circumferential windings, said windings being embedded in synthetic resin.  11. Device according to one of claims 1 to 10, characterized in that it comprises a support member (9, 10) of the explosive charge (8) disposed at a central throttle (5) of the inner surface of the hollow body (2).  12. Device according to claim 11, characterized in that the support member is a shoemaker (9) provided with a closure cover (12).  13. Device according to claim 12, characterized in that the boot (9) is supported by a transverse plate fixed on the inner wall of the hollow body (2), said plate being preferably produced in the form of a support disc ( 10) having a central recess (11).  14. Device according to one of claims 1 to 13, characterized in that the hollow body (2) is provided externally with gripping means, such as one or more handles (13) fixed on the external surface of said hollow body .