Classifications

• • C—CHEMISTRY; METALLURGY
  • C06—EXPLOSIVES; MATCHES
  • C06C—DETONATING OR PRIMING DEVICES; FUSES; CHEMICAL LIGHTERS; PYROPHORIC COMPOSITIONS
  • C06C15/00—Pyrophoric compositions; Flints
• • C—CHEMISTRY; METALLURGY
  • C06—EXPLOSIVES; MATCHES
  • C06B—EXPLOSIVES OR THERMIC COMPOSITIONS; MANUFACTURE THEREOF; USE OF SINGLE SUBSTANCES AS EXPLOSIVES
  • C06B21/00—Apparatus or methods for working-up explosives, e.g. forming, cutting, drying
  • C06B21/0033—Shaping the mixture
  • C06B21/0041—Shaping the mixture by compression
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F42—AMMUNITION; BLASTING
  • F42B—EXPLOSIVE CHARGES, e.g. FOR BLASTING, FIREWORKS, AMMUNITION
  • F42B33/00—Manufacture of ammunition; Dismantling of ammunition; Apparatus therefor
  • F42B33/007—Making cavities in an explosive or propulsive charge
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F42—AMMUNITION; BLASTING
  • F42B—EXPLOSIVE CHARGES, e.g. FOR BLASTING, FIREWORKS, AMMUNITION
  • F42B4/00—Fireworks, i.e. pyrotechnic devices for amusement, display, illumination or signal purposes
  • F42B4/26—Flares; Torches

Definitions

• the present invention relates to primed pyrotechnic breads, their method of manufacture and their use.
• the blocks or pyrotechnic loaves concerned by this invention comprise a priming composition integrated directly into said blocks, and are advantageously obtained by compression, casting or extrusion. They are advantageously used as infrared lures, typically in the conventional domain and the spectral domain.
• a pyrotechnic bread is a solid block, optionally decomposing into several subparts or layers, the composition, geometry and volume of which may differ, and comprising at least one layer of a pyrotechnic composition.
• Pyrotechnic rolls can be characterized by radial combustion (from the outside to the inside), or by axial combustion (also called "cigarette type combustion").
• the present invention is preferably aimed at pyrotechnic bars having a radial combustion.
• Such pyrotechnic breads are intended for various civil or military applications, such as missile lure by infrared emission.
• the combustion of an infra-red pyrotechnic bread is characterized by its luminance, its duration and its rising edge (speed and intensity on ignition).
• the luminance is directly related to the nature of the pyrotechnic composition itself.
• the duration of the combustion is not only a function of the nature of the composition, but also of the geometry of the bread.
• the rising edge is generally provided by the concomitant use of a priming composition.
• pyrotechnic breads called “primed” that is to say that these pyrotechnic rolls are shaped and generally grooved so as to receive in their free grooves the priming composition in pasty form.
• pyrotechnic breads described in patent FR 2 729 749 which comprise a pyrotechnic composition in the form of a grooved block, in the grooves of which has been deposited a priming composition.
• the method of priming pyrotechnic loaves is generally long and expensive, in particular in terms of:
• the priming composition is deposited in the free grooves of the pyrotechnic block, usually manually or automatically (for examples of automatic processes see in particular EP 0 665 415, US 6,427,599, EP 0 309 097 ).
• the initiating composition most often comprises a thermosensitive, thermosetting or thermoplastic crosslinking agent.
• the removal of the priming composition in the form of paste in the grooves of the pyrotechnic block generally results in a weak cohesion between the priming paste and the pyrotechnic block, which influences the physical and mechanical properties of the pyrotechnic bread initiated.
• This weak cohesion leads to poor transmission of (combustion) fires between the different layers, which generates a combustion profile and therefore non-optimal infrared emission.
• the prior art further discloses primed pyrotechnic breads not intended for infrared decoy applications having axial combustion. These include US 2001/013384, US 8,465,606, US 3,744,418, US 5,466,314, US 2,868,129, DE 876,822 and US 2013/0036932, which furthermore do not mention the addition of grooves on the pyrotechnic bread.
• the applicant has developed a method for producing pyrotechnic bread, primed, typically radial combustion, to overcome the problems of the prior art.
• this new manufacturing process makes it possible to access pyrotechnic rolls initiated in a few operations, with numerous advantages in terms of mechanical strength, integration (for example in the DSMF, Firing Safety Device). ), reducing vulnerability, especially to mechanical aggression (for example MURAT classification), cohesion between block and priming, performance, saving time, while significantly reducing manufacturing and removal costs.
• the present invention thus relates to a method of manufacturing a pyrotechnic bread primed in the form of a multilayer block preferably grooved, said method comprising the following successive steps:
• the method according to the invention is simplified compared to the methods of the prior art, since the priming composition is shaped at the same time as the main composition.
• the present invention also relates to a particular texture of the priming composition, for obtaining an IR block initiated in a single compression operation, while maintaining its geometry and dimensions.
• the priming composition is no longer in the form of a paste, but in the same form as the main pyrotechnic composition, making it possible to overcome the problems of segregation or density.
• the present invention also relates to a pyrotechnic bread, comprising at least: a) a layer (a) of a priming composition,
• the present invention also relates to a pyrotechnic device comprising a pyrotechnic bread according to the invention.
• the present invention also relates to the use of a pyrotechnic bread or device according to the invention as infrared decoy.
• the meaning of "bread or pyrotechnic block” means a solid block, optionally decomposing into several sub-parts or layers, whose composition, geometry and volume may differ.
• a pyrotechnic bread comprises at least one main composition.
• the pyrotechnic bread according to the invention is intended for civil or military applications, such as missile lure by infrared emission, in particular in the classical and spectral domain.
• a "main composition” comprises a mixture of at least one oxidant and at least one reducing agent, the combustion of which generates infrared-radiating chemical species.
• the main compositions produce, as a result of the combustion, a high emission in the infrared, according to a specific profile, and possibly gases and / or fumes, or a combination thereof.
• the term "main composition” will be used to refer to the term "infrared composition”.
• the main compositions can be either of "conventional” type or of "spectral” type.
• the main conventional compositions are defined as compositions with strong reducing agents (magnesium for example) having a high combustion temperature with an IR emission of the black body type.
• the term "spectral principal composition” means compositions having a specific infrared radiation in particular IR bands (band I and band II) with a band II / band I ratio greater than the so-called conventional compositions.
• the meaning of "priming composition” or “ignition composition” means a composition for initiating the main pyrotechnic block, on a defined surface, in a defined time.
• the term "primed pyrotechnic bread (or block)” means a pyrotechnic bread (or block) comprising at least one main composition layer and a priming composition layer.
• the primed multilayered bread is in the form of a multilayer block.
• radial combustion is understood to mean combustion that takes place from the outside of the material burning towards the center of the pyrotechnic bread (from the outside towards the inside, see FIG. 5a).
• a radial combustion takes place along a radius of the cylinder, from the outside to the inside.
• a radial combustion also means a combustion which takes place from the outside of the parallelepiped towards its center, according to the transverse direction for example.
• Radial combustion opposes axial combustion, which in turn occurs from an outer layer to an opposite outer layer of material along an axis thereof (see Figure 5b).
• axial combustion takes place from a circular base to the other circular base for example.
• composition in the form of dry grains is intended to mean that the composition (principal or initiator) is in the form of a granular solid (optionally powder) with a determined particle size, the composition comprising at most 5% by weight, for example between 3 and 4% by weight, of solvent relative to the total weight of the composition.
• solvent means any organic and / or aqueous solvent compatible with the composition (main or priming), that is to say in particular any organic and / or aqueous solvent inert with respect to the composition and to obtain grains still slightly moist.
• the present invention thus relates to a method of manufacturing a pyrotechnic bread primed in the form of a multilayer block, said method comprising the following successive steps: 1) successive arrangement, in a shaping tool, of at least:
• the primer pyrotechnic bread obtained by this process has a radial combustion.
• the main layer is the majority layer of bread, that is to say, it represents the largest proportion by weight of the pyrotechnic bread initiated.
• the main composition layer is between 60 and 95% by weight, especially between 80 and 92% by weight relative to the weight of the total primer pyrotechnic bread.
• the term "formatting" means an operation to fix the final shape of the pyrotechnic bread.
• the shaping is carried out by compression, casting or extrusion, even more preferably by compression.
• the method according to the present invention comprises few operations compared to the methods of the prior art.
• the method according to the present invention thus essentially comprises a first stage of disposition of the main and priming compositions, typically in the form of grains, and then a shaping step, typically by compression, in order to obtain a primed pyrotechnic bread.
• the method according to the invention comprises a single shaping step, step (2).
• the method according to the invention makes it possible to obtain breads which are primed directly at the end of the shaping step (2). It therefore does not generally require a boot step or additional formatting.
• the primed bread obtained directly at the end of the shaping step (2) can thus be used as it is in a pyrotechnic device, the priming composition being already deposited on the main infrared composition in the bread (by compression unique).
• the shaping is carried out in a compression tool capable of receiving the appropriate amounts of priming composition and main composition, and being able to withstand high pressure.
• a compression tool capable of receiving the appropriate amounts of priming composition and main composition, and being able to withstand high pressure.
• the tools used are not specific of the process, but is identical to what is conventionally used in the art.
• a compression mold having a main body having a volume capable of receiving the compositions, a compression piston equipped with adapted punches (in particular grooved) and a demolding piston; all being able to withstand strong pressures.
• the method according to the invention advantageously comprises a step 3) demolding the pyrotechnic bread.
• the initiating composition and the main composition are in the form of solid powder or dry grains, having a calibrated particle size preferably between 0.5 and 5 mm, more preferably between 0.5 mm and 2 mm. more preferably between 0.8 and 1.2 mm.
• the compression is uniaxial. This typically takes place under a pressure of between 5 KPa and 50 KPa (5 tons and 50 tons) depending on the composition (s) used.
• the compression is advantageously carried out at ambient temperature or at a temperature between 30 ° C. and 120 ° C., preferably between 30 ° C. and 80 ° C.
• the method according to the invention advantageously comprises a step 3 ') of drying the pyrotechnic bread.
• the drying is preferably carried out in an oven.
• the priming and main compositions have a texture and a viscosity compatible with a casting step.
• the pyrotechnic roll obtained is grooved typically in the longitudinal direction.
• the presence of grooves makes it possible to better circulate the hot gases and thus to impart a more efficient combustion regime to the priming composition, with a homogeneous and rapid ignition of all the primed surfaces.
• the grooves increase the contact surface between the hot air and the grooved bread, which ensures a better homogeneity of the radial combustion.
• Grooving is particularly advantageous when radial combustion is desired.
• the grooving is obtained through the shaping step by the use of tools equipped with punches having a suitable shape (including grooving).
• the compartment in which the compositions are poured priming and main is such that the shape obtained after compression corresponds to that of a grooved block.
• the section of the die has a grooved profile.
• the compositions are advantageously cast in molds having grooved imprints.
• the method according to the invention does not require a shaping step other than step (2), the geometry of the bread at the end of this step (2), in particular as regards the number and the geometry grooves, generally corresponds to that of the finished product (pyrotechnic bread directly usable in a pyrotechnic device).
• the method according to the invention makes it possible to obtain pyrotechnic bars with "free" grooves of any composition, the priming composition being already integrated into the bread (see FIGS. 1 to 4).
• the pyrotechnic roll is shaped so as to obtain a parallelepipedal or cylindrical multilayer block, preferably grooved, typically in the longitudinal direction.
• the grooved layer comprises or consists of the priming composition.
• FIGS. 1 and 2 An example of a grooved parallelepiped pyrotechnic roll is given in FIGS. 1 and 2.
• the multilayer block according to the invention comprises at least two layers, the priming composition layer and the main composition layer.
• the resulting block is trilayer.
• the pyrotechnic roll preferably comprises a central layer of a main composition, "sandwiched" or coated on two opposite sides (two opposite faces in the case of a parallelepiped, or two radially opposite layers in the case of a cylinder) or on both sides by a priming composition layer.
• the process according to the invention then comprises the following successive stages:
• the step 1) further comprises the provision of a layer (c) of priming composition, so that the layer (b) of the main composition is coated on two sides of a priming composition (a) and (c).
• the priming compositions are identical in layers (a) and (c).
• layers (a) and (c) contain the same amount by weight of initiator composition.
• the three-layer pyrotechnic roll obtained has grooves on at least two opposite faces, preferably on the faces of the priming composition.
• the method according to the invention makes it possible to obtain breads which are primed directly at the end of the shaping step (2). It therefore does not require an additional boot step in the general case.
• the primed roll obtained directly at the end of the shaping step (2) can thus be used as such in a pyrotechnic device.
• the method according to the invention makes it possible to obtain pyrotechnic loaves with "free" grooves of any composition, the priming composition being already integrated into the bread (see FIGS. 4) ⁇
• the method according to the invention thus makes it possible to manufacture "double-initiated" pyrotechnic bars.
• the method comprises an additional step of depositing a composition additional priming element (a '), preferably in the form of a paste, in the grooves of the primed and grooved pyrotechnic bread according to the invention.
• the additional priming composition (a ') is identical to or different from the starting composition (s) used in the priming layer (s).
• the additional priming composition (a ') is for example manually deposited in the grooves of the pyrotechnic bread primed and grooved according to the invention.
• the doubly primed pyrotechnic roll thus has the advantage of providing a greater energy at the initiation of the block (high power on ignition) and thus to obtain a higher performance rising edge.
• This particular embodiment thus combines the advantages of the previously used methods and the method according to the invention, the latter making it possible to obtain a pyrotechnic bread primed with free grooves, which was not the case for certain processes of the prior art, which is filled with priming composition which is in the form of viscous paste on the first priming layer obtained by compression - hence the name "double priming".
• the methods of the prior art with manual removal of the priming layer in the grooves of the pyrotechnic bread, consisting only of main composition did not allow to obtain "doubly primed" breads.
• this relates to a method of manufacturing a pyrotechnic bread primed in the form of a multilayer block typically grooved in the longitudinal direction, said method comprising the following successive steps:
• the primer pyrotechnic bread obtained according to this variant advantageously retains a radial combustion.
• the main layer is the majority layer of bread, that is to say, it represents the largest proportion by weight of the pyrotechnic bread initiated.
• the main composition layer is between 60 and 95% by weight, especially between 80 and 92% by weight relative to the weight of the total primer pyrotechnic bread.
• the shaping is carried out in a compression tool capable of receiving the appropriate amounts of priming composition and main composition, and being able to withstand high pressure.
• a compression tool capable of receiving the appropriate amounts of priming composition and main composition, and being able to withstand high pressure.
• a compression mold having a main body having a volume capable of receiving the compositions, a compression piston equipped with suitable punches (typically grooved punches) and a demolding piston; all being able to withstand strong pressures.
• the method advantageously comprises a single compression forming step.
• the method advantageously comprises a step 3) of demolding the pyrotechnic bread.
• the main composition and the initiating composition are in the form of solid powder or dry grains, having a calibrated particle size preferably between 0.5 and 5 mm, even more preferably between 0.5 mm and 2 mm, more preferably between 0.8 and 1.2 mm.
• the compression is uniaxial. This typically takes place under a pressure of between 5 KPa and 50 KPa (5 tons and 50 tons) depending on the composition (s) used.
• the compression is advantageously carried out at ambient temperature or at a temperature between 30 ° C. and 120 ° C., preferably between 30 ° C. and 80 ° C.
• the pyrotechnic bread can be shaped so as to obtain a parallelepipedal, or cylindrical, multilayer block.
• the method may also include a further step of depositing an additional priming composition (a '), preferably in paste form, into the grooves of the primed pyrotechnic bread according to this preferred embodiment.
• the additional priming composition (a ') is identical to or different from the (or) starting composition (s) used in the (or) priming layer (s).
• the additional priming composition (a ') is for example manually deposited in the grooves of the primed pyrotechnic bread.
• the block obtained is trilayer.
• the pyrotechnic roll preferably comprises a central layer of a main composition, "sandwiched" or coated on two opposite sides (two opposite faces in the case of a parallelepiped, or two radially opposite layers in the case a cylinder) or on both sides of a priming composition layer.
• the process then comprises the following successive steps:
• a shaping tool 1) successive arrangement in this order, in a shaping tool, of: a) a first layer (a) of priming composition, b) a layer (b) of main composition, c) a second layer (c) ) priming composition; 2) compression forming, in particular using grooved punches.
• the priming compositions in layers (a) and (c) may be the same or different. Typically, layers (a) and (c) contain the same amount by weight of initiator composition.
• the three-layer pyrotechnic roll obtained has grooves on at least two opposite faces, preferably on the faces of the priming composition.
• the process according to the invention makes it possible to significantly reduce the cost and the production time of the pyrotechnic primed loaves, in particular by reducing the number of operations carried out in the production process.
• a single compression step is sufficient to obtain a primed pyrotechnic roll, directly usable in a pyrotechnic device.
• a single compression step is sufficient to obtain the cohesion of all layers of the pyrotechnic bread.
• the process according to the invention makes it possible to reduce the amount of solvents used, since it is no longer necessary to work with a mixture with a controlled viscosity (mixture in the form of a paste, for example).
• the method according to the invention makes it possible to reduce or even to eliminate certain steps such as drying, especially in the case of compression shaping, when the compositions are thermoplastic (conventional lure).
• the method according to the invention also makes it possible to manufacture pyrotechnic loaves of novel structure, and to improve the cohesion between the priming composition and main composition layers. Since the interface between the priming and main layers is more intimately connected, the combustion (generally radial) is more regular and there is a decrease or even a suppression of the transient combustion conditions.
• the present invention also provides a method as described above, further comprising a step of crosslinking by heating, when the priming or main compositions are thermosetting (spectral decoy).
• the process according to the invention makes it possible, during the crosslinking, to create chemical bonds between the block and the priming, provided that the same type of binder (resin type) is used between the block and the priming. , thereby increasing the mechanical strength and the fire transmission between the block and the priming.
• the invention also proposes to provide pyrotechnic primed loaves, in the form of a multilayer block preferably grooved, obtainable by the process according to the invention, comprising at least one layer of priming composition and a layer of main composition.
• the pyrotechnic blocks initiated according to the invention have a particular arrangement.
• the step of priming the loaves is no longer performed after the shaping and baking step, but during the shaping step, preferably during the compression step.
• the composition of the pyrotechnic block is "sandwiched" between the priming composition which is typically in the form of dry grains in the compression tooling.
• Primed pyrotechnic bread advantageously has a radial combustion.
• the main layer is the majority layer of bread, that is to say, it represents the largest proportion by weight of the pyrotechnic bread initiated.
• the main composition layer is between 60 and 95% by weight, especially between 80 and 92% by weight relative to the weight of the total primer pyrotechnic bread.
• the main composition of the bread or block is a classic decoy.
• such a composition is preferably intended to emit in the infrared.
• a main composition comprises an MTV mixture (magnesium, Teflon, Viton), typically comprising:
• a reducing agent preferably magnesium, zirconium, boron or their mixtures, and
• the first fluorinated polymer being chosen from polytetrafluoroethylene
• the second fluorinated polymer being a fluoroelastomer advantageously chosen from copolymers of vinylidene fluoride, hexafluoropropylene, perfluoromethylvinyl ether and / or tetrafluoroethylene or PMF (polymonofluoride).
• carbon polymers or their co-polymers such as polypropylene, polybutadiene, polycarbonate, polyethylene or polystyrene.
• the initiator composition used in combination with a conventional master composition is thermoplastic.
• it comprises an MTV mixture (magnesium, Teflon, Viton), typically comprising:
• a reducing agent preferably magnesium, zirconium, boron or their mixtures, and
• the first fluorinated polymer being chosen from polytetrafluoroethylene
• the second fluorinated polymer being a fluoroelastomer advantageously chosen from copolymers of vinylidene fluoride, hexafluoropropylene, perfluoromethylvinylether and / or tetrafluoroethylene or PMF (polymonofluoride), optionally, between 2 and 8% of carbon polymers or their co-polymers such as polypropylene, polycarbonate, polyethylene or polystyrene.
• the block thus initiated during compression can be directly integrated into the DSMF (Safety and Firing Device).
• the main composition of the bread or block constitutes a spectral decoy.
• such a composition is intended to emit in the infrared range.
• such a main composition is a mixture comprising:
• a resin selected from a polyester resin, epoxy, polybutadiene or its co-polymers
• IPDI Isophoron diisocyanate
• oxidant such as ammonium perchlorate, ammonium nitrate, potassium nitrate, potassium chlorate or potassium perchlorate,
• RDX 1,3,5-Trinitroperhydro-1,3,5-triazine
• HMX cyclotetramethylene-tetranitramine
• reducing agent such as aluminum, zirconium, or mixtures thereof.
• the initiator composition used in combination with a spectral main composition is a thermosetting resin.
• a thermosetting resin Preferably, it consists of a mixture comprising:
• a resin selected from a polyester resin, epoxy, polybutadiene or its co-polymers
• IPDI Isophoron diisocyanate
• oxidant such as ammonium perchlorate, ammonium nitrate, potassium nitrate, potassium chlorate or potassium perchlorate,
• RDX 1,3,5-Trinitroperhydro-1,3,5-triazine
• HMX cyclotetramethylene-tetranitramine
• reducing agent such as aluminum, zirconium, or mixtures thereof.
• the bread or primer block is placed in the oven after compression, to create chemical bonds between the block and the boot.
• the consequence is a clear improvement in the cohesion between the priming composition and the main composition, which further improves the profile of infrared emission during combustion (and overall decoy performance), in particular by suppressing the transient regimes during the passage of the combustion of the priming layer at the main layer.
• the pyrotechnic bread primed according to the invention is grooved, as described above.
• the pyrotechnic bread is "doubly primed".
• it comprises an additional priming composition (a ') in the grooves of the primed and grooved pyrotechnic bread according to the invention.
• the additional priming composition (a ') is identical to or different from the starting composition (s) used in the priming layer (s).
• the resulting bread is three-layered.
• the pyrotechnic roll preferably comprises a central layer of a main composition (b), "sandwiched" or coated on two opposite sides (two opposite faces in the case of a parallelepiped, or two layers radially opposite in the case of a cylinder) or on both sides of a layer of priming composition, layers (a) and (c).
• the priming composition is identical in layers (a) and (c).
• layers (a) and (c) contain the same amount by weight of initiator composition.
• the three-layer pyrotechnic roll obtained has grooves on at least two opposite faces, preferably on the faces of the priming composition.
• the pyrotechnic bread may also consist of several different main compositions sandwiched with the priming composition.
• a main composition is the main composition of the bread. This composition will provide the effect requested during the combustion.
• the main composition is the majority composition of the pyrotechnic bread.
• the priming composition is the initiator composition of this main composition.
• the pyrotechnic bread may be partially sandwiched between the priming composition and the main composition (s) of the bread. Part of the block can thus be started.
• the pyrotechnic bread may be partially grooved (the groove makes it possible to circulate advantageously the ignition gases during the initiation of bread) and initiated. Part of the block can thus be sandwiched between the priming composition and the main composition of the bread.
• the pyrotechnic bread can be primed and not grooved.
• the entire block is primed where the main composition is "sandwiched" by the priming composition over the entire length.
• the pyrotechnic bread can be fully primed with several priming and grooved compositions. Indeed, the main composition is sandwiched with one or more priming compositions.
• the first priming composition can be shaped at the same time as the main composition and the other priming compositions shaped in a second step.
• a priming composition A1 on a preferential part of the block, and then to have an initiating composition A2 on the remainder of the block.
• several different formulations can be used on all or part of the block depending on the performance demand.
• the invention relates to a pyrotechnic bread primed in the form of a grooved multilayer block comprising at least one layer of priming composition and a main composition layer, obtainable by the process according to the invention. in which the shaping step is performed by compression.
• the primed pyrotechnic bread is of the "sandwich” type, that is to say that it comprises three layers: a typically conventional or spectral main composition layer, "sandwiched” or between two layers of composition boot.
• composition of the pyrotechnic block is sandwiched between the two layers of priming composition which is typically in the form of dry grains in the compression tooling.
• the main layer is the majority layer of bread, that is to say, it represents the largest proportion by weight of the pyrotechnic bread initiated.
• the main composition layer is between 60 and 95% by weight, especially between 80 and 92% by weight relative to the weight of the total primer pyrotechnic bread.
• the pyrotechnic breads primed according to the invention have several advantages over prior art primed rolls: improvement of the fire transmission between the block and the priming, resulting notably in a suppression of the transient combustion regimes,
• the pyrotechnic rolls according to the invention have excellent resistance to vibrations, especially with respect to pyrotechnic rolls manufactured according to the methods of the prior art, in particular the methods comprising manual or automatic removal of the priming composition.
• the present invention also relates to a pyrotechnic device comprising a pyrotechnic bread according to the invention.
• the primed bread according to the invention is inserted into a pyrotechnic device.
• This pyrotechnic device is advantageously a cartridge, in which is typically added an initiation system.
• the cartridge is mounted in a charger, to be used from an aircraft.
• the present invention also relates to a use of the pyrotechnic bread according to the invention or the device according to the invention as infrared decoy.
• Figure 1 Diagram of a pyrotechnic bread primed in the form of a parallelepipedal trilayer block comprising a central layer of a main composition (b), "sandwiched” or coated on two opposite sides with a composition layer of priming, layers (a) and (c).
• the bread is grooved on the priming composition layer faces, and the grooves (d) are longitudinal.
• Figure 2 Photograph of pyrotechnic bread primed at the end of the production line in the form of a three-layer block comprising a central layer of a main composition (b), "sandwiched” or coated on two opposite sides of the production line a layer of initiating composition, layers (a) and (c), obtained according to Example 1, in parallelepipedal form.
• Figure 3 Diagram of a pyrotechnic bread primed in the form of a cylindrical three-layer block comprising a central layer of a main composition (b), "sandwiched” or coated on two opposite sides with a layer of composition of priming, layers (a) and (c).
• the bread is grooved on the priming composition layer faces, and the grooves (d) are longitudinal.
• Figure 4 Photograph of pyrotechnic bread primed at the end of the production line as a three-layer block comprising a central layer of a main composition (b), "sandwiched” or coated on two opposite sides of the production line a initiator composition layer, layers (a) and (c), obtained according to example 1, in cylindrical form.
• Figure 5 diagram showing a radial combustion profile (a) or axial (b). The arrows indicate the direction of combustion.
• Figure 6 Radiometric measurement of spectral type infrared lures in dynamic configuration. Curve in solid lines: three-layer bread sandwich type according to the invention. Dotted curve: Bread made according to the prior art. There is a significant improvement in performance at the beginning of combustion, with an excellent fire transition between the block and the priming.
• the x-axis represents time.
• the y-axis represents luminance (in Watt per steradian).
• Figure 7 Radiometric measurement of classic type infrared lures in static configuration. Curve in solid lines: three-layer bread sandwich type according to the invention. Dotted curve: Bread made according to the prior art. There is a significant improvement in performance at the beginning of combustion, with an excellent fire transition between the block and the priming.
• the x-axis represents time.
• the y-axis represents luminance (in Watt per steradian).
• compositions of the block then of the priming are granulated to obtain a calibrated grain size of about 1.2 mm. Then the grains obtained are dried at 50 ° C for 2h, in order to evaporate the solvent. The compositions are thus obtained in the form of non-crosslinked dry grains.
• the priming composition is a mixture comprising:
• a resin selected from a polyester resin, epoxy, polybutadiene or its co-polymers
• IPDI Isophoron diisocyanate
• oxidant such as ammonium perchlorate, ammonium nitrate, potassium nitrate, potassium chlorate or potassium perchlorate, between 2 and 5% of energetic molecules such as RDX (1,3,5-Trinitroperhydro-1,3,5-triazine), HMX (cyclotetramethylene-tetranitramine), and
• reducing agent such as aluminum, zirconium, or mixtures thereof.
• the priming composition of the layer a) is then on the side of the grooved punches.
• the second priming layer c) is uniformly arranged over the entire surface above the layer b). The priming composition of the layer c) is then on the side of the grooved punches.
• the dosing of the compositions and their depositing in the compression tooling can be done automatically and the masses can be adjusted according to the gauges.
• the piston is then lowered on this series of layers to apply a compression ratio of 10 KPa (10 tons) for 10 seconds.
• the compression ratio is adapted to the caliber manufactured.
• the whole is then demolded, by an automatic cycle of the press, by reverse thrust.
• the primed IR block is thus obtained directly in a single compression step.
• the primed block is then placed in an oven at 70 ° C for 5 days to undergo crosslinking to bind the main composition layer to the priming composition layers. Chemical bonds are thus created between the main composition layer and the priming composition layers.
• a photograph of the bread thus obtained by the process according to the invention is given in FIG. 6a or 6b (as a function of the shape of the compression tooling).
• the firing safety device (DSMF) is added to perform the cartridge integration.
• the cartridge is positioned on a cart that will be launched at a certain speed on a rail, then the decoy cartridge will be launched to simulate an ejection under the plane.
• Measuring means such as radiometers and thermographs are arranged to measure the infra-red performance of the breads, in dynamic shots.
• FIG. 6 shows, on the one hand, that the rising edge obtained with a block according to the invention is faster and higher than with a block according to the prior art and, secondly, that the block / priming transition is more marked by a dip in performance (block according to the prior art) corresponding to a transient combustion regime, but a continuous measurement of the infrared signal (block according to the invention).
• Figures 6 and 7 illustrate the disappearance of the transient regime obtained with the pyrotechnic rolls initiated according to the invention, both in dynamic or static fire conditions.
• the loaves according to the invention make it possible to increase the rates, to simplify the process which requires much less means and personnel, to have a significant improvement in the transition of the combustion between the priming composition and the main composition (with elimination of transient combustion conditions), which makes it possible in particular to increase the rising edge, but also gives the priming composition a better mechanical strength (passage of vibration and shock tests and strong cohesion with the bread).

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Citations (11)

• 2014
  • 2014-05-27 FR FR1454805A patent/FR3021653B1/fr active Active
• 2015
  • 2015-05-27 SG SG11201609942XA patent/SG11201609942XA/en unknown
  • 2015-05-27 KR KR1020167036455A patent/KR20170019379A/ko unknown
  • 2015-05-27 EP EP15725614.0A patent/EP3148957B1/fr active Active
  • 2015-05-27 WO PCT/EP2015/061739 patent/WO2015181246A1/fr active Application Filing
• 2016
  • 2016-11-24 IL IL249211A patent/IL249211B/he active IP Right Grant
  • 2016-12-21 ZA ZA2016/08822A patent/ZA201608822B/en unknown

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