EP0025732B2 - Delay fuse with a low combustion rate and a small diameter - Google Patents

Delay fuse with a low combustion rate and a small diameter Download PDF

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Publication number
EP0025732B2
EP0025732B2 EP80401194A EP80401194A EP0025732B2 EP 0025732 B2 EP0025732 B2 EP 0025732B2 EP 80401194 A EP80401194 A EP 80401194A EP 80401194 A EP80401194 A EP 80401194A EP 0025732 B2 EP0025732 B2 EP 0025732B2
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Prior art keywords
delay
weight
delay fuse
diameter
tungsten
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German (de)
French (fr)
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EP0025732B1 (en
EP0025732A3 (en
EP0025732A2 (en
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Paul-Philippe Cord
Louis Guy
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Societe Nationale des Poudres et Explosifs
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Societe Nationale des Poudres et Explosifs
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    • CCHEMISTRY; METALLURGY
    • C06EXPLOSIVES; MATCHES
    • C06CDETONATING OR PRIMING DEVICES; FUSES; CHEMICAL LIGHTERS; PYROPHORIC COMPOSITIONS
    • C06C5/00Fuses, e.g. fuse cords

Definitions

  • these compositions mainly combine a reducing agent such as boron, magnesium, aluminum, silicon, titanium, manganese, chromium, zirconium, niobium, molybdenum, tungsten or thorium with an oxide of transition metal or to one or more oxygenated oxidizing salts of alkali or alkaline earth metals such as chlorates, perchlorates, nitrates, oxides, peroxides, 2 chromates and dichromates of these metals.
  • a non-negligible proportion of these compositions may consist of inert materials intended to reduce the liveliness of the composition.
  • the delay relays are relatively large metal parts since the delay column, that is to say the part which contains the pyrotechnic composition, has a diameter of at least 5 mm therein, while the outside diameter of these devices is meanwhile at least 8 mm.
  • a delay cord having an internal diameter of 1 mm in diameter can only have a combustion speed greater than about 10 mm / s for an outside diameter of at least 12 mm since any reduction in the thickness of the metal wall of the cord can only increase the combustion speed of the latter.
  • the invention relates to a delay cord having a combustion speed less than or equal to 4 mm / s and containing a pyrotechnic composition based on tungsten, barium chromate and potassium perchlorate, characterized in that it has a diameter less than or equal to 3 mm, the ratio of the outside diameter to the diameter of the core occupied by the pyrotechnic composition being between 1.4 and 2.0 and in that this pyrotechnic composition is free of silica and consists of 25 to 45% by weight of tungsten with a particle size between 2 and 6 ⁇ , from 45 to 65% in weight of barium chromate and 8 to 15% by weight of potassium perchlorate.
  • the outer envelope of the delay cords according to the invention is produced in a conventional manner from a metal or a metal alloy, preferably ductile and with a low melting point.
  • a metal or a metal alloy preferably ductile and with a low melting point.
  • Lead and lead-based alloys especially those based on tin and / or antimony are very suitable.
  • a woven sheath or an extruded synthetic material is also possible to use.
  • the delay cords according to the invention can be manufactured in a usual manner and known per se. For example, they can be obtained from a ductile metal cord of relatively large diameter (10-25 mm), containing the composition indicated above, by passing said cord through dies of decreasing diameters. The delay induced by the string can be precisely adjusted by measuring the rate of combustion of a fragment of the latter leaving the die.
  • the cords according to the invention can also be obtained by progressive reduction of the diameter by successive passages in the various grooves of decreasing sections of a rolling mill or by a series of passes with the rolling mill followed by a series of passes in dies. A section reduction ratio at each pass of the order of 0.9, conventionally used, is suitable.
  • the delay cords according to the invention generally have an outside diameter of between 1.5 and 3 mm and a the actual density of the compositions which they contain is in practice much lower than the theoretical values and between 2.7 and 4, 0 g / cm 3 , preferably between 3.0 and 3.4 g / cm 3 ,
  • the delay cords according to the invention also show excellent thermostability since their self-ignition temperature is commonly greater than 500 ° C. Furthermore, their exceptionally low combustion speed taking into account the weakness of their diameter is only subject to very small variation as a function of temperature: a variation of only 10% is commonly observed between -60 ° C and + 75 ° C, which is considered remarkable.
  • the delay cords according to the invention make it possible to ensure, with a excellent reliability and in a wide range of conditions, delays of a few tens of seconds to several minutes and even several hours while occupying a very small volume and releasing little combustion heat, which ultimately has the effect of considerably reducing the weight of thermal protections surrounding said delay cords, in pyrotechnic systems on board spacecraft or submarines.
  • the delay cords according to the invention are illustrated by the following nonlimiting examples.
  • the latter is done in small successive quantities of a few cm 3 and, after each introduction, the composition is compacted using a piston by applying a pressure of approximately 16 bars.
  • the tube closed at each end by a lead plug is then transformed into a cord with an outside diameter of 2 mm by a series of passages in successive dies of decreasing diameters; the section reduction ratio on each pass is of the order of 0.9 so that 20 passes are necessary to obtain said delay cord whose internal diameter is 1.26 mm.
  • This cord has a combustion speed of 3.4 mm / s. Just 20.4 cm of cord to induce a delay of 60 seconds in a pyrotechnic chain.
  • the delay cord was further tested in accordance with Example 13.
  • the density of the composition it contained was 3.2 g / cm 3 .
  • Its combustion speed is surprisingly stable since it goes from 2.44 mm / s at room temperature to 2.31 mm / s at -60 ° C and to 2.5 mm / s at + 70 ° C.
  • the cord still works perfectly. It does not self-ignite until around 510 ° C.

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Air Bags (AREA)
  • Fuses (AREA)

Description

L'invention se rapporte aux cordeaux-retards, c'est-à-dire aux cordeaux renfermant une composition pyrotechnique à vitesse de combustion relativement lente, laquelle est confinée dans une gaine généralement métallique.The invention relates to delay cords, that is to say to cords containing a pyrotechnic composition with a relatively slow combustion rate, which is confined in a generally metallic sheath.

La mise à feu d'un tel cordeau-retard, éventuellement provoquée par un signal pyrotechnique, permet d'induire, dans une chaîne pyrotechnique qui le contient, un ralentissement ou un retard considérable dans la progression d'un signal pyrotechnique.The firing of such a delay cord, possibly caused by a pyrotechnic signal, makes it possible to induce, in a pyrotechnic chain which contains it, a slowdown or a considerable delay in the progression of a pyrotechnic signal.

On connaît de nombreuses compositions pyrotechniques capables de brûler à une vitesse relativement lente de l'ordre de quelques centimètres à quelques dizaines de centimètres à la seconde.There are many known pyrotechnic compositions capable of burning at a relatively slow speed of the order of a few centimeters to a few tens of centimeters per second.

Généralement, ces compositions associent principalement un réducteur tel que le bore, le magnésium, l'aluminium, le silicium, le titane, le manganèse, le chrome, le zirconium, le niobium, le molybdène, le tungstène ou le thorium à un oxyde de métal de transition ou à un ou plusieurs sels oxydants oxygénés des métaux alcalins ou alcalinoterreux tels que les chlorates, perchlorates, nitrates, oxydes, peroxydes, 2 chromates et bichromates de ces métaux. Une proportion non négligeable de ces compositions peut être constituée de matériaux inertes destinés à réduire la vivacité de la composition. Des compositions de ce type, qui sont très classiquement utilisées dans les relais-retards sont définies par les normes militaires américaines MIL-T-23132 du 21 décembre 1961 et 23132A du 16 juin 1972. Elles sont par exemple employées dans le brevet américain 4 144 814 et consistent en des mélanges comportant de 30 à 60% en poids de tungstène de granulométrie comprise entre moins de 1 um et 10 um, de 30 à 60% en poids de chromate de baryum, de 5 à 9% en poids de perchlorate de potassium et environ 5% de silice, sous forme de terre de diatomées.Generally, these compositions mainly combine a reducing agent such as boron, magnesium, aluminum, silicon, titanium, manganese, chromium, zirconium, niobium, molybdenum, tungsten or thorium with an oxide of transition metal or to one or more oxygenated oxidizing salts of alkali or alkaline earth metals such as chlorates, perchlorates, nitrates, oxides, peroxides, 2 chromates and dichromates of these metals. A non-negligible proportion of these compositions may consist of inert materials intended to reduce the liveliness of the composition. Compositions of this type, which are very conventionally used in delay relays are defined by the American military standards MIL-T-23132 of December 21, 1961 and 23132A of June 16, 1972. They are for example used in American patent 4 144 814 and consist of mixtures comprising from 30 to 60% by weight of tungsten with a particle size between less than 1 μm and 10 μm, from 30 to 60% by weight of barium chromate, from 5 to 9% by weight of perchlorate of potassium and about 5% silica, in the form of diatomaceous earth.

Toutefois les relais-retards sont des pièces métalliques de relativement grande taille puisque la colonne-retard, c'est-à-dire la partie qui contient la composition pyrotechnique, y a un diamètre d'au moins 5 mm, tandis que le diamètre extérieur de ces dispositifs est quant à lui d'au moins 8 mm.However, the delay relays are relatively large metal parts since the delay column, that is to say the part which contains the pyrotechnic composition, has a diameter of at least 5 mm therein, while the outside diameter of these devices is meanwhile at least 8 mm.

Compte tenu que ces relais-retards exhibaient une vitesse de combustion attractive de l'ordre de 1 à 5 mm/s, on a cherché à employer les compositions de ladite norme MIL-T-23132 dans des dispositifs de taille encore plus réduite en réduisant le diamètre des colonnes-retards.Given that these delay-relays exhibited an attractive combustion speed of the order of 1 to 5 mm / s, we sought to use the compositions of said standard MIL-T-23132 in devices of even smaller size by reducing the diameter of the delay columns.

Les résultats des ces tentatives sont rapportés dans l'article de S.G. NESBITT intitulé "A study of fast burning tungsten delay compositions in small column diameters" exposé au IVème Symposium de Pyrotechnie, tenu du 22 au 26 juillet 1974, à DENVER, COLORADO. Cet auteur a observé que pour des compositions appartenant à la Série 1 de ladite norme, c'est-à-dire pour des compositions relativement les plus rapides ayant une vitesse de combustion de plusieurs dizaines de millimètres à la seconde, on a généralement encore une bonne propagation de la combustion dans des tubes métallique de 12 mm de diamètre extérieur et de 1 mm seulement de diamètre intérieur. Toutefois, cet auteur note que la plus lente des compositions qu'il a testé, brûlant à 9,4 mm/s, donne 60% de ratés avec ce diamètre de colonne de 1 mm seulement. Or, il est bien connu qu'en matière de relais, diminuer l'épaisseur des parois métalliques provoque une plus grande concentration de la chaleur au niveau de la composition pyrotechnique et donc une accélération de la vitesse de combustion de cette dernière. On peut consulter à ce sujet, l'ouvrage de base intitulé "Military and Civilian Pyrotechnics" de H. ELLERN, Chemical Publishing Company, 1968.The results of these attempts are reported in the article by S.G. NESBITT entitled "A study of fast burning tungsten delay compositions in small column diameters" exposed at the 4th Symposium of Pyrotechnics, held from July 22 to 26, 1974, in DENVER, COLORADO. This author observed that for compositions belonging to Series 1 of said standard, that is to say for relatively quickest compositions having a combustion speed of several tens of millimeters per second, there is generally still a good propagation of combustion in metal tubes of 12 mm outside diameter and only 1 mm inside diameter. However, this author notes that the slowest of the compositions he tested, burning at 9.4 mm / s, gives 60% of misfires with this column diameter of only 1 mm. However, it is well known that in terms of relays, reducing the thickness of the metal walls causes a greater concentration of heat at the level of the pyrotechnic composition and therefore an acceleration of the combustion speed of the latter. One can consult on this subject, the basic work entitled "Military and Civilian Pyrotechnics" of H. ELLERN, Chemical Publishing Company, 1968.

Il résulte finalement de ce qui précède qu'actuellement, pour l'homme de l'art, un cordeau-retard présentant un diamètre intérieur de 1 mm de diamètre ne peut posséder qu'une vitesse de combustion supérieure à environ 10 mm/s pour un diamètre extérieur d'au moins 12 mm puisque toute diminution de l'épaisseur de la paroi métallique du cordeau ne peut qu'augmenter la vitesse de combustion de ce dernier.It finally follows from the above that currently, for those skilled in the art, a delay cord having an internal diameter of 1 mm in diameter can only have a combustion speed greater than about 10 mm / s for an outside diameter of at least 12 mm since any reduction in the thickness of the metal wall of the cord can only increase the combustion speed of the latter.

On comprend que de tels cordeaux ne sont pas utilisables pour des retards longs du fait de leur vitesse de combustion élevée et du fait de leur poids dans des systèmes embarqués à bord d'engins spatiaux ou de sous-marins. La seule possibilité de diminuer ce poids paraît donc, en conservant les compositions connues, d'utiliser un diamètre intérieur plus grand, de l'ordre de 3 à . 5 mm et une épaisseur de paroi plus faible: toutefois cette solution qui conduit à des performances satisfaisantes du point de vue de la fiabilité et des vitesses de combustion (des compositions plus lentes peuvent être adoptées ce qui compense l'accélération due à l'amincissement de la paroi), s'avère en revanche rédhibitoire du point de vue du poids emporté car le gain de poids réalisé est plus que compensé par le poids des protections thermiques supplémentaires à prévoir; en effet le doublement du diamètre intérieur de cordeau provoque un quadruplement de la quantité de chaleur dégagée par la composition pyrotechnique.It is understood that such cords cannot be used for long delays because of their high combustion speed and because of their weight in systems on board spacecraft or submarines. The only possibility of reducing this weight therefore appears, while keeping the known compositions, to use a larger internal diameter, of the order of 3 to. 5 mm and a lower wall thickness: however this solution which leads to satisfactory performance from the point of view of reliability and combustion rates (slower compositions can be adopted which compensates for the acceleration due to thinning of the wall), on the other hand turns out to be prohibitive from the point of view of the weight carried because the weight gain achieved is more than offset by the weight of the additional thermal protections to be provided; in fact the doubling of the internal diameter of the cord causes a quadrupling of the amount of heat released by the pyrotechnic composition.

Dans ces conditions, la réalisation d'un cordeau-retard qui possède à la fois une bonne fiabilité, un faible diamètre intérieur et extérieur et une faible vitesse de combustion parait impossible.Under these conditions, the production of a delay cord which has both good reliability, a small internal and external diameter and a low combustion speed seems impossible.

L'invention concerne un cordeau-retard ayant une vitesse de combustion inférieure ou égale à 4 mm/s et contenant une composition pyrotechnique à base de tungstène, de chromate de baryum et de perchlorate de potassium, caractérisé en ce qu'il possède un diamètre inférieur ou égal à 3 mm, le rapport du diamètre extérieur au diamètre du l'âme occupée par la composition pyrotechnique étant compris entre 1,4 et 2,0 et en ce que cette composition pyrotechnique est exempte de silice et est constituée de 25 à 45 % en poids de tungstène de granulométrie comprise entre 2 et 6 µ, de 45 et 65 % en poids de chromate baryum et de 8 à 15 % en poids de perchlorate de potassium.The invention relates to a delay cord having a combustion speed less than or equal to 4 mm / s and containing a pyrotechnic composition based on tungsten, barium chromate and potassium perchlorate, characterized in that it has a diameter less than or equal to 3 mm, the ratio of the outside diameter to the diameter of the core occupied by the pyrotechnic composition being between 1.4 and 2.0 and in that this pyrotechnic composition is free of silica and consists of 25 to 45% by weight of tungsten with a particle size between 2 and 6 μ, from 45 to 65% in weight of barium chromate and 8 to 15% by weight of potassium perchlorate.

Selon un mode préférentiel de réalisation de l'invention on utilise du tungstène ayant une granulométrie comprise entre 2 et 4 µm. En effet lorsqu'une granulométrie supérieure à 4 µm et inférieure à 2 µm est utilisée, on risque de constater des défauts d'allumage de la composition, notamment lorsque cette dernière contient moins de 35% en poids de tungstène.According to a preferred embodiment of the invention, tungsten having a particle size of between 2 and 4 μm is used. In fact, when a particle size greater than 4 μm and less than 2 μm is used, there is a risk of ignition defects in the composition, in particular when the latter contains less than 35% by weight of tungsten.

Selon un mode particulièrement préféré de réalisation de l'invention la composition de remplissage du cordeau-retard comprend seulement de 29 à 35% en poids de tungstène de granulométrie comprise entre 2 et 4 µm, de 55 à 62% en poids de chromate de baryum et de 9 à 12% en poids de perchlorate de potassium, L'incorporation de silice est rédhibitoire dans les compositions utilisées dans le cadre de l'invention.According to a particularly preferred embodiment of the invention, the filling composition of the delay cord comprises only from 29 to 35% by weight of tungsten with a particle size between 2 and 4 μm, from 55 to 62% by weight of barium chromate and from 9 to 12% by weight of potassium perchlorate. The incorporation of silica is unacceptable in the compositions used within the framework of the invention.

L'enveloppe extérieure des cordeaux-retards selon l'invention est réalisée d'une manière classique en un métal ou un alliage métallique de préférence ductile et à bas point de fusion. Le plomb et les alliages à base de plomb, notamment ceux à base d'étain et/ou d'antimoine conviennent bien. Toutefois, on peut également utiliser une gaine tissée ou un matériau synthétique extrudé mais cela est d'un faible intérêt en pratique.The outer envelope of the delay cords according to the invention is produced in a conventional manner from a metal or a metal alloy, preferably ductile and with a low melting point. Lead and lead-based alloys, especially those based on tin and / or antimony are very suitable. However, it is also possible to use a woven sheath or an extruded synthetic material, but this is of little interest in practice.

Les cordeaux-retards selon l'invention peuvent être fabriqués d'une manière habituelle et connue en soi. Par exemple, on peut les obtenir à partie d'un cordeau en métal ductile de diamètre relativement élevé (10-25 mm), contenant la composition indiquée ci-dessus, par passage de cedit cordeau dans des filières de diamètres décroissants. Le retard induit par le cordeau peut être réglé avec précision en mesurant la vitesse de combustion d'un fragment de ce dernier au sortir de la filière. On peut aussi obtenir les cordeaux selon l'invention par réduction progressive du diamètre par passages successifs dans les diverses gorges de sections décroissantes d'un laminoir ou par une série de passes au laminoir suivie d'une série de passes dans des filières. Un rapport de réduction de section à chaque passe de l'ordre de 0,9, classiquement utilisé, convient bien.The delay cords according to the invention can be manufactured in a usual manner and known per se. For example, they can be obtained from a ductile metal cord of relatively large diameter (10-25 mm), containing the composition indicated above, by passing said cord through dies of decreasing diameters. The delay induced by the string can be precisely adjusted by measuring the rate of combustion of a fragment of the latter leaving the die. The cords according to the invention can also be obtained by progressive reduction of the diameter by successive passages in the various grooves of decreasing sections of a rolling mill or by a series of passes with the rolling mill followed by a series of passes in dies. A section reduction ratio at each pass of the order of 0.9, conventionally used, is suitable.

Les cordeaux-retards selon l'invention ont en genéral un diamètre extérieur compris entre 1,5 et 3 mm et un la densité réelle des compositions qu'ils renferment est en pratique très inférieure aux valeurs théoriques et comprise entre 2,7 et 4,0 g/cm3, de préférence entre 3,0 et 3,4 g/cm3,The delay cords according to the invention generally have an outside diameter of between 1.5 and 3 mm and a the actual density of the compositions which they contain is in practice much lower than the theoretical values and between 2.7 and 4, 0 g / cm 3 , preferably between 3.0 and 3.4 g / cm 3 ,

Les cordeaux-retards selon l'invention montrent de plus une excellente thermostabilité puisque leur température d'autoinflammation est couramment supérieure à 500°C, Par ailleurs, leur vitesse de combustion exceptionellement basse compte tenu de la faiblesse de leur diamètre ne subit qu'une très faible variation en fonction de la température: une variation de 10% seulement est couramment constatée entre -60°C et + 75°C, ce qui est considéré comme remarquable.The delay cords according to the invention also show excellent thermostability since their self-ignition temperature is commonly greater than 500 ° C. Furthermore, their exceptionally low combustion speed taking into account the weakness of their diameter is only subject to very small variation as a function of temperature: a variation of only 10% is commonly observed between -60 ° C and + 75 ° C, which is considered remarkable.

Il résulte de tous les avantages précités auquel s'ajoute le fait que la combustion des compositions selon l'invention s'accompagne d'un dégagement gazeux nul ou négligeable, que les cordeaux-retards selon l'invention permettent d'assurer, avec une excellente fiabilité et dans une grande plage de conditions, des retards de quelques dizaines de secondes à plusieurs minutes et même plusieurs heures tout en occupant un très faible volume et en dégageant peu de chaleur de combustion, ce qui a finalement pour effet d'alléger considérablement le poids des protections thermiques entourant lesdits cordeaux-retards, dans les systèmes pyrotechniques embarqués à bord d'engins spatiaux ou sous-marins. Pour apprécier pleinement l'intérêt des cordeaux=retards selon l'invention, on notera que le simple fait de pouvoir diminuer de moitié le diamètre d'un cordeau-retard permet de réduire d'un facteur 4 la quantité de chaleur de combustion qu'il dégage, à vitesse de combustion égale. On peut ainsi réaliser des enroulements à spires jointives sans avoir à craindre un allumage intempestif d'une spire à l'autre.It follows from all the above advantages to which is added the fact that the combustion of the compositions according to the invention is accompanied by zero or negligible gas evolution, that the delay cords according to the invention make it possible to ensure, with a excellent reliability and in a wide range of conditions, delays of a few tens of seconds to several minutes and even several hours while occupying a very small volume and releasing little combustion heat, which ultimately has the effect of considerably reducing the weight of thermal protections surrounding said delay cords, in pyrotechnic systems on board spacecraft or submarines. To fully appreciate the value of the cords = delays according to the invention, it will be noted that the simple fact of being able to halve the diameter of a delay cords makes it possible to reduce by a factor of 4 the amount of combustion heat that it gives off, at equal combustion speed. It is thus possible to make windings with contiguous turns without having to fear an untimely ignition from one turn to another.

Les cordeaux-retards selon l'invention sont illustrés par les exemples non limitatifs suivants;The delay cords according to the invention are illustrated by the following nonlimiting examples;

Exemple 1Example 1

On a rempli un tube en plomb antimonieux à 5% d'antimoine de 17 mm de diamètre extérieur et de 12 mm de diamètre intérieur à l'aide d'une composition constituée de 32% en poids, de tungstène de granulomètrie 2 um, 58% en poids de chromate de baryum et 10% de perchlorate de potassium.A 5% antimony antimony lead tube 17 mm in outside diameter and 12 mm in inside diameter was filled with a composition consisting of 32% by weight, of tungsten with a particle size of 2 μm, 58 % by weight of barium chromate and 10% of potassium perchlorate.

Pour obtenir une bonne régularité de remplissage, ce dernier se fait par petites quantités successives de quelques cm3 et, après chaque introduction on vient tasser la composition à l'aide d'un piston en appliquant une pression de 16 bars environ.To obtain good regularity of filling, the latter is done in small successive quantities of a few cm 3 and, after each introduction, the composition is compacted using a piston by applying a pressure of approximately 16 bars.

Le tube obturé à chaque extrémité par un bouchon de plomb est ensuite transformé en cordeau de diamètre extérieur de 2 mm par une série de passages dans des filières successives de diamètres décroissants; le rapport de réduction de section à chaque passe est de l'ordre de 0,9 si bien que 20 passes sont nécessaires pour obtenir ledit cordeau-retard dont le diamètre intérieur est de 1,26 mm.The tube closed at each end by a lead plug is then transformed into a cord with an outside diameter of 2 mm by a series of passages in successive dies of decreasing diameters; the section reduction ratio on each pass is of the order of 0.9 so that 20 passes are necessary to obtain said delay cord whose internal diameter is 1.26 mm.

Ce cordeau a une vitesse de combustion de 3,4 mm/s. Il suffit de 20,4 cm de cordeau pour induire un retard de 60 secondes dans une chaîne pyrotechnique.This cord has a combustion speed of 3.4 mm / s. Just 20.4 cm of cord to induce a delay of 60 seconds in a pyrotechnic chain.

Exemples 2 à 21Examples 2 to 21

On a fabriqué plusieurs cordeaux-retards selon l'invention en utilisant le procédé décrit à l'exemple 1.Several delay cords were made according to the invention using the method described in Example 1.

Les compositions utilisées, les dimensions des cordeaux obtenus et les performances de ces derniers à température ambiante sont rapportées dans le tableau suivant:

Figure imgb0001

  • (a) De: diamètre extérieur du cordeau
  • (b) Di: diamètre intérieur du cordeau ou diamètre d'âme occupée par la composition
  • (c) Vc: vitesse de combustion
  • (d) L60: longueur pour obtenir un retard de 60 secondes
  • (e) Ri m: retard obtenu avec 1 mètre de cordeau.
The compositions used, the dimensions of the cords obtained and the performances of the latter at room temperature are reported in the following table:
Figure imgb0001
  • (a) From: outside diameter of the cord
  • (b) Di: inner diameter of the cord or core diameter occupied by the composition
  • (c) Vc: burning rate
  • (d) L 60 : length to obtain a delay of 60 seconds
  • (e) R i m: delay obtained with 1 meter of cord.

On a testé de manière plus approfondie encore le cordeau-retard selon l'exemple 13. La densité de la composition qu'il renfermait était de 3,2 g/cm3. Lors de son fonctionnement il ne dégageait que 90 cm3 de gaz par mètre linéaire (volume ramené aux conditions normales). Sa vitesse de combustion est étonnament stable puisqu'elle passe de 2,44 mm/s à température ambiante à 2,31 mm/s à -60°C et à 2,5 mm/s à + 70°C. A 110°C le cordeau fonctionne encore parfaitement. Il ne s'autoenflamme qu'à partir d'environ 510°C.The delay cord was further tested in accordance with Example 13. The density of the composition it contained was 3.2 g / cm 3 . During operation, it emitted only 90 cm 3 of gas per linear meter (volume reduced to normal conditions). Its combustion speed is surprisingly stable since it goes from 2.44 mm / s at room temperature to 2.31 mm / s at -60 ° C and to 2.5 mm / s at + 70 ° C. At 110 ° C the cord still works perfectly. It does not self-ignite until around 510 ° C.

Claims (6)

1. Delay fuse having a rate of combustion which is less than or equal to 4 mm/s and containing a pyrotechnic composition having a base of tungsten, barium chromate and potassium perchlorate, characterised in that it possesses an external diameter less than or equal to 3 mm, the ratio of the external diameter to the diameter of the core occupied by the pyrotechnic composition being between 1.4 and 2.0, and in that said pyrotechnic composition is free of silica and consists of from 25 to 45% by weight of tungsten having a particle size of between 2 and 6 µm, from 45 to 658 by weight of barium chromate and from 8 to 15% by weight of potassium perchlorate.
2. Delay fuse according to claim 1, characterised in that the composition for filling the delay fuse comprises only from 28 to 35% by weight of tungsten, from 55 to 62% by weight of barium chromate and from 9 to 12% by weight of potassium perchlorate.
3. Delay fuse according to one of claims 1 or 2, characterised in that the particle size of tungsten is less than 4µm.
4. Delay fuse according to claim 1, characterised in that the real density of the pyrotechnic composition is between 2.8 and 3.6 g/cm3, preferably between 3.0 and 3.4 g/cm3.
5. Delay fuse according to claim 1, characterised in that the envelope of the fuse consists of lead or a leadbased alloy.
6. Pyrotechnic sequence comprising a delay fuse according to any one of the preceding claims.
EP80401194A 1979-09-06 1980-08-20 Delay fuse with a low combustion rate and a small diameter Expired EP0025732B2 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR7922278A FR2464932A1 (en) 1979-09-06 1979-09-06 SLOW-SPEED, LOW-DIAMETER COMBUSTION SPEED
FR7922278 1979-09-06

Publications (4)

Publication Number Publication Date
EP0025732A2 EP0025732A2 (en) 1981-03-25
EP0025732A3 EP0025732A3 (en) 1982-02-10
EP0025732B1 EP0025732B1 (en) 1983-12-14
EP0025732B2 true EP0025732B2 (en) 1986-09-24

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Application Number Title Priority Date Filing Date
EP80401194A Expired EP0025732B2 (en) 1979-09-06 1980-08-20 Delay fuse with a low combustion rate and a small diameter

Country Status (5)

Country Link
US (1) US4356768A (en)
EP (1) EP0025732B2 (en)
JP (1) JPS5641894A (en)
DE (1) DE3065888D1 (en)
FR (1) FR2464932A1 (en)

Families Citing this family (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3808366A1 (en) * 1988-03-12 1989-10-05 Dynamit Nobel Ag DELAY SETS WITH LONG DELAY TIMES
FR2706449B1 (en) * 1993-06-18 1995-08-11 Giat Ind Sa Pyrotechnic composition for delay cords.
US5501154A (en) * 1993-07-06 1996-03-26 Teledyne Industries, Inc. Substantially lead-free tin alloy sheath material for explosive-pyrotechnic linear products
US5333550A (en) * 1993-07-06 1994-08-02 Teledyne Mccormick Selph Tin alloy sheath material for explosive-pyrotechnic linear products
CN100335859C (en) * 2001-11-24 2007-09-05 刘必坤 Timing fuse for fireworks bomb and its making process
US20040055495A1 (en) * 2002-04-23 2004-03-25 Hannagan Harold W. Tin alloy sheathed explosive device
RU2532572C1 (en) * 2013-08-01 2014-11-10 Открытое акционерное общество "Федеральный научно-производственный центр "Научно-исследовательский институт прикладной химии" Pyrotechnical delay composition

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3173367A (en) * 1963-05-17 1965-03-16 Commerical Solvents Corp Composition comprising barium chromate, boron and lead dioxide
US3528864A (en) * 1965-09-21 1970-09-15 Us Navy High impulse explosives containing tungsten
US3664898A (en) * 1969-08-04 1972-05-23 Us Navy Pyrotechnic composition
US3684594A (en) * 1970-05-15 1972-08-15 Hercules Inc Aqueous explosive compositions having reversible fluent-nonfluent properties
FR2166732A5 (en) * 1972-01-06 1973-08-17 Poudres & Explosifs Ste Nale Lead sheathed detonating fuse - with stainless steel outer sheath
US3901747A (en) * 1973-09-10 1975-08-26 Allied Chem Pyrotechnic composition with combined binder-coolant
US4144814A (en) * 1976-07-08 1979-03-20 Systems, Science And Software Delay detonator device

Also Published As

Publication number Publication date
DE3065888D1 (en) 1984-01-19
EP0025732B1 (en) 1983-12-14
JPS6317800B2 (en) 1988-04-15
EP0025732A3 (en) 1982-02-10
JPS5641894A (en) 1981-04-18
FR2464932B1 (en) 1982-06-04
FR2464932A1 (en) 1981-03-20
EP0025732A2 (en) 1981-03-25
US4356768A (en) 1982-11-02

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