EP1269105B1 - Dual operating pyrotechnic charge - Google Patents

Description

Technical field of the invention

The present invention relates to a pyrotechnic charge with dual operation.

It is a multi-mission load, also known as a multi-mission load, with two modes of operation to efficiently attack multiple types of targets.

The multiplicity of threats and the requested reduction in unit costs imply a need for new charges that are versatile or versatile.

Prior art

This type of multi-mission load is being studied in various American centers, as shown by a simple search on the Internet, for example the study of an anti-aircraft and anti-ballistic missile load on the "Navy" missile -SM2- block IVA at www.chinfo.navy.1000 / navpalib / weapons / missiles / standart / standarthtml.

Most on-board military loads such as missiles, shells, mines, etc., are splatter charges generated by the explosion of a pyrotechnic device that may increase the damage to the intended target.

But these loads are subject, among other design constraints to mass limitations and in volume. This has led to search for optimized devices around an operating point, and in fact to a single function. This operating point depends on the mission and the load carrier.

There are a large number of flash charges in various systems. The document Conventional Warhead Systems - Physics Engineering - Richard M. Lloyd-Progress in Astronautics and Aeronautics - Paul Zarchan - Vol.179, preface March 1998, Lavoisier, describes a number of these charges.

These prior art charges, however, all have in common that they have only one mode of operation, see the configuration of the pyrotechnic charge described in US-A-4,655,139, which covers the characteristics of the preamble. of claim 1.

Presentation of the invention

The present invention is specifically intended to overcome the aforementioned drawbacks by providing a pyrotechnic load dual operation that meets the multi-mission requirements mentioned above.

The pyrotechnic charge according to the invention comprises a nominal explosive charge surrounded by a detonating secondary explosive charge surrounded by a fragment generator surrounded by a protective envelope,

this pyrotechnic charge further comprising a first priming means and a second priming means, the first and second priming means being controllable independently from control means, for optionally transmitting a pyrotechnic order respectively to the nominal explosive charge or secondary explosive charge, the detonation of the secondary explosive charge not causing the initiation of the nominal explosive charge, and wherein the secondary explosive charge is in the form of pellets or bands of a secondary explosive distributed in an inert wave damper material.

Thus, this pyrotechnic charge has two modes of operation according to the explosive charge to which the pyrotechnic order is transmitted: an "energetic" mode against rapidly evolving missiles, that is to say at a relative speed ≥ 1500 m / s, a mode called "energy game" against slowly evolving missiles that is to say at a relative speed <1500 m / s.

The pyrotechnic charge of the present invention may further comprise a chip generator cutting line placed between the secondary explosive charge and the chip generator and / or between the protective envelope and the chip generator, and a third priming means, the third priming means being independently controllable from the control means for transmitting a pyrotechnic order to the cutting line, the detonation of the cutting line not damaging the secondary explosive charge and not causing the priming of the nominal explosive charge.

• la composition explosive vendue par la Société SNPE (FRANCE) commercialement sous le nom de V350 est décrite dans la demande de brevet FR-A-2 671 549, et
• la composition explosive vendue par la société SNPE connue sous le nom de V401 à base d'octogène (HMX) dans un liant fluoré, qui est plus énergétique que la précédente,
• toute composition comparable en densité, sensibilité et énergie divulguée à ce jour.

The nominal explosive charge preferably has the highest possible energy density to reduce its mass, and the highest density possible so that it is not initiated by the detonation of the secondary explosive charge. This nominal explosive may be for example:

• the explosive composition sold by the company SNPE (FRANCE) commercially under the name V350 is described in the patent application FR-A-2,671,549, and
• the explosive composition sold by the company SNPE known under the name of V401 based on octogen (HMX) in a fluorinated binder, which is more energetic than the previous one,
• any composition comparable in density, sensitivity and energy disclosed to date.

Preferably, the nominal explosive charge is not in contact with the secondary explosive charge. The space between the nominal explosive charge and the flash generator depends in particular directly on the density of the main explosive and the sensitivity of the explosive to initiation.

According to the invention the secondary explosive charge must detonate without priming the nominal explosive. The fact that this detonating explosive is essential to respect the chronometry necessary during the engagement phase of the use of the load. Indeed, the total decomposition after the ignition signal of the secondary explosive charge must preferably be obtained in less than 100 μs, which imposes a detonation regime.

This explosive charge is therefore, in accordance with the present invention, in the form of pellets or strips of a low energy secondary explosive distributed in a material inert wave damper, this set forming an explosive architecture.

The secondary explosive may be of the same nature as the nominal explosive if it is sufficiently sensitive. This may be the V350, but also more sensitive, comparable octogenous compositions, or bands, for example V401. According to the present invention, a pentrite composition, easy to shape and very good detonation, can also be used. The secondary explosive can therefore, because of its nature and its conformation in the pyrotechnic charge of the present invention, be initiated in the same way as the nominal explosive.

The mass of the secondary explosive to be used is proportional to the kinetic energy ratio that one wishes to communicate to the chips between the two operations. Indeed, for a given "slice of load", the kinetic energy imparted to the chips is a function of the explosive mass that detonates.

According to the invention, the inert material may be, for example in the form of a foam such as a porous plastic or a honeycomb, metallic or composite honeycomb structure, having for example a density of about 0, 2 to 0.3.

The non-priming of the main explosive is essentially provided by the vacuum formed by the cells of the foam which acts as a damper.

The foam can also fill a space left between the nominal explosive and the chip generator. This space can be about 10 mm. The layer formed by the inert material and the explosive secondary can be partially structuring and participate in the mechanical strength of the load.

For "energetic" operation, the abovementioned damping material and secondary composition act as a disturbance of the main stress, during fragmentation into "small chips" of the chip generator. This disturbance remains low, due to the energy ratio between the nominal explosive and the secondary explosive. The ignition delay or pyrotechnic delay, existing between the nominal explosive on the one hand and the network of cords and the secondary composition, on the other hand, must make it possible to reduce the influence of a local concentration of explosive, likely to disturb the desired speed field of the chips.

The chip generator according to the present invention is capable of generating according to the operating mode, ie according to the pyrotechnic order chosen, respectively large splinters in an "energetic" operation or small chips in low energy operation.

In order to maximize the effectiveness of the chips, it is preferable that the chip generator be of dense metal selected for example from tantalum, tungsten, and steel. Tantalum is preferred for its good ductility properties. Tungsten is also suitable, however it may have problems of metallurgical fragility binding for speeding which limits the effectiveness of chips. The choice of a steel chip generator is also however, the effectiveness of splinters seems less.

• du rayon moyen du générateur d'éclat, en faisant l'hypothèse que l'épaisseur de la charge explosive secondaire est constante et que les variations de rayon moyen du générateur d'éclats correspondent à des variations du rayon de la charge nominale,
• de l'épaisseur du générateur d'éclat.

The chip generator may consist of a one-piece assembly. It can be in the form of a piece of revolution, of varying thickness. The exact profile of this generator and the thickness are determined to precisely obtain the desired speed field in energy operation. In a "slice of load", the speed of the chips depends in first approximation, for a given radius of charge:

• the mean radius of the burst generator, assuming that the thickness of the secondary explosive charge is constant and that the variations in mean radius of the chip generator correspond to variations in the radius of the rated load,
• the thickness of the spark generator.

Qualitatively, the higher the average radius, the faster the chips will be, and the smaller the thickness, the faster the chips will be.

The generator of the profile and the thickness of the brightness generator are adjusted in each slice, in order to obtain the "good" speed distribution. It is thus possible to generate splinters varying in a ratio of mass and speed of up to twenty (ratio of more than 400 on the kinetic energy).

The small chips can be obtained by controlled fragmentation for example by means of an electron beam or by machining: that is to say that the whole chip generator is pre-cut according to inclined lines, for example by inclination close to 45 ° in order to allow the appearance of constraints "spreading" the pre-fragmentation lines with respect to the axis of revolution of the assembly.

The large chips can be obtained by cutting the monobloc chip generator using at least two cutting lines or a network of detonating cords. It is possible to use the lines of weakness of the small chips, for example a line on n lines, but it is preferable not to superimpose the cutting network of the big chips and small chips, to leave more latitude for the obtaining large chips and to limit mass losses at both ends of the spark generator cylinder, for example in triangular form.

According to a variant of the present invention the brightness generator is such that it can operate without the cutting cords. According to this variant, splitting the chip generator into small chips or large chips is obtained according to the pyrotechnic energy supplied: in small chips if the bias is high, ie if the nominal load is initiated, and in big splinters if the solicitation is weak, ie if the secondary charge is initiated. This can be achieved for example by using a structuring shell placed between the secondary explosive and the chip generator. The ferrule is a cylinder of circular section and of curved generator, for example hyperboloid. The thickness of the cylinder is a priori constant. The ferrule may be for example steel or titanium this which represents a weight gain for the pyrotechnic charge. The large chips may be composed for example of preformed fragmentation projectiles, for example a set of parallelepipeds. The large chips may be bonded together to provide some structural strength for example by gluing or inter-chip welding by means of an electron beam. The small chips can be obtained for example or by controlled fragmentation: the small chips are from a precut accentuated large chips (for example to the electron beam or machining), or by "preformed fragmentation": small chips are parallelepipeds embedded in a matrix. This matrix can be a polymer, a fusible metal, for example aluminum, or an explosive material for a dispersive effect of the chips, if the explosion takes place near the load, or amplifier of efficiency, if explosion takes place in contact with the target.

In this variant, the detonation of the explosive architecture is just reflected by a swelling of the ferrule which speeds up the large chips that remain consistent. When all the explosive detonates the high stress generated has the effect of breaking all the links between the small chips.

The influence of the damping material on the dynamics of large chips is negligible, even favorable: it has an attenuation and homogenization effect. The energy loss due to this influence can be offset, if necessary, by a small increase in the explosive mass of explosive architecture. The shock absorber layer may according to the embodiment of the present invention, and in particular depending on the choice of the chip generator material, be necessary to attenuate the intensity of the detonation shock wave of the secondary explosive and thus allow the generation of flakes integrity. This is the case, for example, for a tungsten chip generator obtained by sintering.

From the same principle, that is to say from explosive compositions that detonate distinctly, it is possible to increase the number of operating modes, replacing the explosive architecture and the chip generator by a succession of layers. explosive which can be separately primed, thus delivering in stages several ranges of kinetic energy of chips.

According to the invention, the chip generator can also ensure the structuring of the pyrotechnic charge with respect to the external mechanical stresses.

The envelope serves to protect in its cycle of use the load of the present invention external attacks such as mechanical aggression, thermal, dust, moisture, etc., during its operational life. The nature of this envelope therefore depends strongly on the load utilization environment.

In addition, it is involved in the operation of the load because it is part of the projected material. It should as much as possible not disrupt the speed of shrapnel in the "low energy" mode.

For example, in an application as a missile performing an aerobic flight, it must be able to withstand a heat flow that is sizing

It can be made for example of insulating composite material.

When present, the splitter chisels can be placed on either side of the chip generator. They can also be placed between the protective envelope and the chip generator, or between the secondary charge and the chip generator. The position on either side of the splinter generator makes it possible to avoid crossing the cords.

The control means may for example comprise a charge control box and a switch. The control unit performs the function of transmitting the firing order from the client, for example an electrical command, to the means, also called system, of initiation.

The priming system comprises the first priming means, or primary priming means for the initiation of the nominal load, consisting of a pyrotechnic cord, also called main cord, and an amplifier. The priming system further comprises the second priming means for priming the secondary explosive, as well as a triggering network for the detonating fuses of the generator chips, and a detonation switch placed between the control box and the amplifier.

The switch can operate as a switch. It can, depending on the order received from the client, for example the control box, to cut or not the boot line of the nominal explosive. The switch can be integrated into the control box. It does not call into question the safety because in case of untimely operation it does not detonate the charges.

When the secondary explosive is in the form of explosive pellets, the second priming means may comprise, for example, a network of detonating cords for priming said pellets. The initiation of this network of detonating cords can be obtained by adding a derivation from the main cord. The initiation of the cutting line may be obtained by adding a bypass between the control box and the aforementioned bypass for the secondary ignition.

In the case of "low energy" operation of the pyrotechnic charge of the present invention, it is preferable to adjust the timing of ignition of the detonating cord and the secondary composition with respect to that of the nominal explosive. This can be ensured for example by adjusting the length of the detonation paths, but also by adding delay lines introducing start delays.

The inventors have therefore provided a pyrotechnic charge comprising two types of operation to attack choice and effectively multiple types of targets. The device of the present invention can generate either small fast bursts, effective against a slowly evolving threat, or large slow bursts effective against a rapidly evolving threat.

In addition, the combination of the two operations in a single load allows a gain in mass and volume in the load carrier, and consequently a gain in efficiency and overall costs: reduction of the number of carriers, simplification of the maintenance and operational implementation etc.

Other features and advantages will become apparent on reading the examples which follow, given by way of illustration and without limitation, with reference to the appended figure.

Brief description of the figure

• Figure 1 is a simplified diagram of an embodiment of the pyrotechnic charge according to the invention comprising a cutting line of the chip generator.

Examples Example 1: Pyrotechnic charge according to the present invention with a cutting line of the chip generator.

FIG. 1 is a simplified diagram of one embodiment of the pyrotechnic charge according to FIG. the present invention comprising a cutting line of the chip generator.

The pyrotechnic charge (1) comprises a nominal explosive charge (3) surrounded by a detonating secondary explosive charge (5) surrounded by a chip generator (7) surrounded by a protective envelope (9), said pyrotechnic charge further comprising a first priming means (11,13) and a second priming means (15), the first and second priming means being independently controllable from control means (17,19), for optionally transmitting a pyrotechnic order respectively to the nominal explosive charge (3) or the secondary explosive charge (5), so that the detonation of the secondary explosive charge does not cause the initiation of the nominal explosive charge.

The pyrotechnic charge further comprises two cutting cords (21) of the chip generator placed between the secondary explosive charge (5) and the chip generator (7), and a third initiation means (not shown). The third priming means is controlled independently from the control means (17, 19) for transmitting a pyrotechnic order to the cutting cords (21), so that the detonation of the cutting line does not damage the explosive charge. secondary and does not cause the initiation of the nominal explosive charge.

• Explosif nominal : V350 de densité 1,70 ; sous forme d'une pièce de révolution, de rayon moyen 0,048, de masse 6,157 kg.
• Explosif lent : V350 de même nature, inséré dans 0,146 kg de mousse, de densité 0,1 sur une épaisseur de 0,096 m, entourant le bloc d'explosif nominal : 0,127 kg de V350, sous forme de bandes d'épaisseur 8 mm, est réparti régulièrement dans la mousse.
• Générateur d'éclats : bloc de tantale, entourant les deux compositions précédentes, d'épaisseur 0,0018 m, de masse 5,351 kg, prédécoupée à l'extérieur selon deux hélices sécantes. Deux cordons de découpe en HNS noyé dans du Pb (hexanitrostilbène) sont disposés autour du générateur d'éclats, le long des deux hélices sécantes : longueur totale de 5,60 m, diamètre extérieur d'environ 4 mm, masse totale de 1600 g dont 33,6 g de HNS.
• Protection thermique : en composite mousse, acier, épaisseur de 10,6 mm pour une masse de 0,276 kg (densité de 0,13).

The characteristics of this load are as follows:

• Nominal explosive: V350 with a density of 1.70; in the form of a piece of revolution, with a mean radius of 0.048 and a mass of 6.157 kg.
• Slow explosive: V350 of the same kind, inserted in 0,146 kg of foam, density 0,1 on a thickness of 0,096 m, surrounding the block of nominal explosive: 0,127 kg of V350, in the form of strips of thickness 8 mm, is regularly distributed in the foam.
• Splinter generator: tantalum block, surrounding the two preceding compositions, thickness 0.0018 m, mass 5.351 kg, pre-cut outside according to two secant propellers. Two HNS cutting cords embedded in Pb (hexanitrostilbene) are arranged around the splinter generator, along the two secant propellers: total length of 5.60 m, outer diameter of about 4 mm, total mass of 1600 g of which 33.6 grams of HNS.
• Thermal protection: composite foam, steel, thickness of 10.6 mm for a mass of 0.276 kg (density of 0.13).

The load is equipped with means of initiation and control, at a height of 0.490 m for an outside radius of 0.0705 m.

Operation of the pyrotechnic charge of the present invention described in Example 1

• l'interrupteur pyrotechnique reçoit ou pas l'ordre de l'organe de décision de couper la ligne d'amorçage nominale,
• le boîtier de commande reçoit l'ordre, par exemple électrique, de l'organe de décision d'initier l'explosion.

The operation is as follows:

• the pyrotechnic switch receives or not the order of the decision member to cut the nominal ignition line,
• the control box receives the order, for example electric, of the decision organ initiating the explosion.

a) energy operation

• the pyrotechnic order is transmitted to the amplifier which initiates the nominal explosive and potentially the Detonant Cord and the Secondary Explosive.
• The main composition detonates, releasing the energy of the nominal explosive and thus causing the speeding of small fast flashes. The sheaf is optimized by sheaf convergence to reduce the area hit on the target. The main composition detonates before the pyrotechnic architecture (secondary explosive) and the detonating cutting line, making a priori obsolete the operation of the latter.

b) low energy operation

• the pyrotechnic order is transmitted only to the Cutting Detonating Cords and the secondary composition,
• the Detonating Cords cut out the "big splinters", without damaging the secondary composition or igniting the nominal explosive, and
• the Secondary Composition detonates without priming the nominal explosive by the action of the explosive architecture which makes it possible to damp the detonation wave. Low energy is then released from the Secondary Composition, speeding up large splinters.

Claims (12)

1. Pyrotechnic charge (1) comprising a nominal explosive charge (3) surrounded by a secondary detonating explosive charge (5), surrounded by a flare generator (7), surrounded by a protection envelope,
   in which said pyrotechnic charge additionally comprises a first priming means (11, 13) and a second priming means (15), the first and second priming means being capable of being commanded independently from command means (17, 19) to transmit by choice a pyrotechnic order respectively to the nominal explosive charge (3) or to the secondary explosive charge (5),
   the detonation of the secondary explosive charge (5) not provoking the priming of the nominal explosive charge (3), and characterised in that
   the secondary explosive charge (5) is in the form of pellets or bands of a secondary explosive distributed in an inert wave damping material (see Claims 8 and 10).
2. Pyrotechnic charge according to Claim 1, comprising at least two cutting cords of the flare generator placed between the secondary explosive charge and the flare generator and/or between the protection envelope and the flare generator, and a third priming means,
   the third priming means being capable of being commanded independently from the command means to transmit a pyrotechnic order to the cutting cord,
   the detonation of the cutting cord not damaging the secondary explosive charge and not provoking the priming of the nominal explosive charge.
3. Pyrotechnic charge according to Claim 1 or 2, in which the command means comprise a charge command box and a switch.
4. Pyrotechnic charge according to Claim 1 or 2, additionally comprising a priming amplifier connected to the nominal explosive charge.
5. Pyrotechnic charge according to Claim 1, in which the inert material is a paste such as a porous plastic or honeycomb, a metallic or composite alveolar structure.
6. Pyrotechnic charge according to Claim 5, in which the inert material has a density ranging from about 0.2 to 0.3.
7. Pyrotechnic charge according to Claim 1, in which the inert material essentially ensures the non-priming of the nominal explosive charge by the detonation of the secondary explosive charge, in which the flare generator generates respectively, depending on the pyrotechnic order chosen, small flares or large flares, and in which the flare generator comprises a double network of controlled fragmentation.
8. Pyrotechnic charge according to Claim 1, additionally comprising a structuring shell placed between the secondary explosive and the flare generator.
9. Pyrotechnic charge according to Claim 1 or 2, in which the flare generator is a composite system of preshaped fragmentation projectiles.
10. Pyrotechnic charge according to Claim 1, in which the flare generator is made of tantalum.
11. Pyrotechnic charge according to Claim 1 or 2, in which the flare generator ensures the structuring of the pyrotechnic charge.
12. Pyrotechnic charge according to Claim 1 or 2, in which the exterior envelope is comprised of an insulating composite material.

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