EP0025732A2 - 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 PDFInfo
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- EP0025732A2 EP0025732A2 EP80401194A EP80401194A EP0025732A2 EP 0025732 A2 EP0025732 A2 EP 0025732A2 EP 80401194 A EP80401194 A EP 80401194A EP 80401194 A EP80401194 A EP 80401194A EP 0025732 A2 EP0025732 A2 EP 0025732A2
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- delay
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- C—CHEMISTRY; METALLURGY
- C06—EXPLOSIVES; MATCHES
- C06C—DETONATING OR PRIMING DEVICES; FUSES; CHEMICAL LIGHTERS; PYROPHORIC COMPOSITIONS
- C06C5/00—Fuses, e.g. fuse cords
Definitions
- 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.
- 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, 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 relay-delays are defined by 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 micron and 10 microns, from 30 to 60% by weight of barium chromate, from 5 to 9% by weight of potassium perchlorate and approximately 5% of silica, in the form of diatomaceous earth.
- 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, characterized in that it has a diameter less than or equal to 3 mm and in that it contains a composition.
- pyrotechnic sition consisting of 25 to 45% by weight of tungsten with a particle size between 2 and 6 microns, preferably between 2 and 4 microns, from 45 to 65% by weight of an alkali or alkaline earth chromate or dichromate and from 8 to 15% by weight of alkaline or alkaline earth perchlorate.
- an alkaline or alkaline earth chromate is used in preference to an alkaline or alkaline earth dichromate and an alkaline earth chromate in preference to an alkaline chromate.
- the barium chromate is particularly preferred. Mixtures of different chromates or dichromates can be used.
- an alkaline perchlorate is used in preference to an alkaline earth perchlorate.
- Sodium perchlorate and, above all, potassium perchlorate are particularly preferred.
- Ammonium perchlorate is less advantageous because its use leads to an increase in the rate of combustion of the composition. Mixtures of different perchlorates can be used.
- tungsten is used having a particle size between 2 and 4 microns.
- a particle size greater than 4 microns and less than 6 microns 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. Tungsten cannot be replaced entirely by any other metal.
- the filling composition of the delay cord comprises only from 28 to 35% by weight of tungsten with a particle size between 2 and 4 microns, from 55 to 62% by weight of chromate of barium and 9 to 12% by weight of potassium perchlorate.
- the incorporation of silica is unacceptable in the compositions used in the context of the invention.
- 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.
- 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 to 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 have an outside diameter of between 1.5 and 3 mm and a ratio of the outside diameter of the delay cords to the diameter of the core occupied by the pyrotechnic composition of between 1.4 and 2.0 .
- 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 above 500 ° C. Furthermore, their exceptionally low combustion speed, given the smallness of their diameter, undergoes only a very small variation depending on the 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:
- 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 microns, 58%. by weight of barium chromate and 10% of potassium perchlorate.
- 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 at 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 rate 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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Abstract
L'invention concerne un cordeau-retard ayant une vitesse de combustion inférieure ou égale à 4 mm/s caractérisé en ce qu'il possède un diamètre inférieur ou égal à 3 mm et en ce qu'il contient une composition pyrotechnique constituée de 25 à 45% en poids de tungstène de granulométrie comprise entre 2 et 4 microns, de 45 à 65% en poids de chromate de baryum et de 8 à 15% en poids de perchlorate de potassium. Le cordeau-retard selon l'invention, muni d'une gaine métallique, trouve notamment son application dans les systèmes pyrotechniques embarqués à bord d'engins spatiaux ou sous-marins.The invention relates to a delay cord having a combustion speed less than or equal to 4 mm / s, characterized in that it has a diameter less than or equal to 3 mm and in that it contains a pyrotechnic composition consisting of 25 to 45% by weight of tungsten with a particle size between 2 and 4 microns, from 45 to 65% by weight of barium chromate and from 8 to 15% by weight of potassium perchlorate. The delay cord according to the invention, provided with a metallic sheath, finds its application in particular in pyrotechnic systems on board spacecraft or submarines.
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 chaine 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 connait 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 alcalino-terreux tels que les chlorates, perchlorates, nitrates, oxydes, peroxydes, 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.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, 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.
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 micron et 10 microns, 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.Compositions of this type, which are very conventionally used in relay-delays are defined by 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 micron and 10 microns, from 30 to 60% by weight of barium chromate, from 5 to 9% by weight of potassium perchlorate and approximately 5% of 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 de 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 I 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 métalliques de 12 mm de diamètre extérieur et de 1 mm seulement de diamètre intérieur. Toutefois, cet auteur note que la plus lente dès 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 SG 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 I of said standard, that is to say for relatively quickest compositions having a combustion rate of several tens of millimeters per second, there is generally still one 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 from the compositions he tested, burning at 9.4 mm / s, gives 60% failures 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 greater concen heat transfer 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 du 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 seems, while keeping the known compositions, to use a larger internal diameter, of the order of 3 to 5 mm and a smaller wall thickness: however this solution which leads to performance satisfactory from the point of view of reliability and burning rates (slower compositions can be adopted which compensates for the acceleration due to the thinning of the wall), on the other hand proves 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 protection 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 paraît 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, caractérisé en ce qu'il possède un diamètre inférieur ou égal à 3 mm et en ce qu'il contient une composition pyrotechnique constituée de 25 à 45% en poids de tungstène de granulométrie comprise entre 2 et 6 microns, de préférence entre 2 et 4 microns, de 45 à 65% en poids d'un chromate ou d'un bichromate alcalin ou alcalino-terreux et de 8 à 15% en poids de perchlorate alcalin ou alcalino-terreux.The invention relates to a delay cord having a combustion speed less than or equal to 4 mm / s, characterized in that it has a diameter less than or equal to 3 mm and in that it contains a composition. pyrotechnic sition consisting of 25 to 45% by weight of tungsten with a particle size between 2 and 6 microns, preferably between 2 and 4 microns, from 45 to 65% by weight of an alkali or alkaline earth chromate or dichromate and from 8 to 15% by weight of alkaline or alkaline earth perchlorate.
Selon un premier mode de réalisation de l'invention, on utilise un chromate alcalin ou alcalino-terreux de préférence à un bichromate alcalin ou alcalino-terreux et un chromate alcalino-terreux de préférence à un chromate alcalin. Le chromate de baryum est particulièrement préféré. Des mélanges de différents chromates ou bichromates peuvent être utilisés.According to a first embodiment of the invention, an alkaline or alkaline earth chromate is used in preference to an alkaline or alkaline earth dichromate and an alkaline earth chromate in preference to an alkaline chromate. The barium chromate is particularly preferred. Mixtures of different chromates or dichromates can be used.
Selon un second mode de réalisation de l'invention on utilise un perchlorate alcalin de préférence à un perchlorate alcalino-terreux. Le perchlorate de sodium et, surtout, le perchlorate de potassium sont particulièrement préférés. Le perchlorate d'ammonium est moins intéressant car son emploi conduit à une augmentation de la vitesse de combustion de la composition. Des mélanges de différents perchlorates peuvent être utilisés.According to a second embodiment of the invention, an alkaline perchlorate is used in preference to an alkaline earth perchlorate. Sodium perchlorate and, above all, potassium perchlorate are particularly preferred. Ammonium perchlorate is less advantageous because its use leads to an increase in the rate of combustion of the composition. Mixtures of different perchlorates can be used.
Selon un troisième mode de réalisation de l'invention, on utilise du tungstène ayant une granulométrie comprise entre 2 et 4 microns. En effet, lorsqu'une granulométrie supérieure à 4 microns et inférieure à 6 microns 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. Le tungstène ne peut être remplacé en totalité par aucun autre métal.According to a third embodiment of the invention, tungsten is used having a particle size between 2 and 4 microns. In fact, when a particle size greater than 4 microns and less than 6 microns 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. Tungsten cannot be replaced entirely by any other metal.
Selon un mode particulièrement préféré de réalisation de l'invention, la composition de remplissage du cordeau-retard comprend seulement de 28 à 35% en poids de tungstène de granulométrie comprise entre 2 et 4 microns, 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 28 to 35% by weight of tungsten with a particle size between 2 and 4 microns, from 55 to 62% by weight of chromate of barium and 9 to 12% by weight of potassium perchlorate. The incorporation of silica is unacceptable in the compositions used in the context 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 partir 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 to 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 un diamètre extérieur compris entre 1,5 et 3 mm et un rapport du diamètre extérieur du cordeau-retard au diamètre de l'âme occupée par la composition pyrotechnique compris entre 1,4 et 2,0. 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/cm 3.The delay cords according to the invention have an outside diameter of between 1.5 and 3 mm and a ratio of the outside diameter of the delay cords to the diameter of the core occupied by the pyrotechnic composition of between 1.4 and 2.0 . 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 exceptionnellement 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 above 500 ° C. Furthermore, their exceptionally low combustion speed, given the smallness of their diameter, undergoes only a very small variation depending on the 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 advantage of the delay cords 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 quantity 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:
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 granulométrie 2 microns, 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 microns, 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 dé 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 at 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 chaine 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.
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 :
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 étonnamment 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 rate 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 (10)
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FR7922278 | 1979-09-06 | ||
| FR7922278A FR2464932A1 (en) | 1979-09-06 | 1979-09-06 | SLOW-SPEED, LOW-DIAMETER COMBUSTION SPEED |
Publications (4)
| Publication Number | Publication Date |
|---|---|
| EP0025732A2 true EP0025732A2 (en) | 1981-03-25 |
| EP0025732A3 EP0025732A3 (en) | 1982-02-10 |
| EP0025732B1 EP0025732B1 (en) | 1983-12-14 |
| EP0025732B2 EP0025732B2 (en) | 1986-09-24 |
Family
ID=9229401
Family Applications (1)
| 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) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2706449A1 (en) * | 1993-06-18 | 1994-12-23 | Giat Ind Sa | Pyrotechnic composition for delay cords. |
Families Citing this family (6)
| 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 |
| US5333550A (en) * | 1993-07-06 | 1994-08-02 | Teledyne Mccormick Selph | Tin alloy sheath material for explosive-pyrotechnic linear products |
| US5501154A (en) * | 1993-07-06 | 1996-03-26 | Teledyne Industries, Inc. | Substantially lead-free 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 |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2166732A5 (en) * | 1972-01-06 | 1973-08-17 | Poudres & Explosifs Ste Nale | Lead sheathed detonating fuse - with stainless steel outer sheath |
| FR2357861A1 (en) * | 1976-07-08 | 1978-02-03 | Systems Science Software | PERFECTED TIMED DETONATOR DEVICE |
Family Cites Families (5)
| 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 |
| US3901747A (en) * | 1973-09-10 | 1975-08-26 | Allied Chem | Pyrotechnic composition with combined binder-coolant |
-
1979
- 1979-09-06 FR FR7922278A patent/FR2464932A1/en active Granted
-
1980
- 1980-08-20 DE DE8080401194T patent/DE3065888D1/en not_active Expired
- 1980-08-20 EP EP80401194A patent/EP0025732B2/en not_active Expired
- 1980-08-21 US US06/179,973 patent/US4356768A/en not_active Expired - Lifetime
- 1980-09-03 JP JP12126580A patent/JPS5641894A/en active Granted
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2166732A5 (en) * | 1972-01-06 | 1973-08-17 | Poudres & Explosifs Ste Nale | Lead sheathed detonating fuse - with stainless steel outer sheath |
| FR2357861A1 (en) * | 1976-07-08 | 1978-02-03 | Systems Science Software | PERFECTED TIMED DETONATOR DEVICE |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2706449A1 (en) * | 1993-06-18 | 1994-12-23 | Giat Ind Sa | Pyrotechnic composition for delay cords. |
| EP0630876A1 (en) * | 1993-06-18 | 1994-12-28 | GIAT Industries | Pyrotechnic composition for delay fuses |
Also Published As
| Publication number | Publication date |
|---|---|
| DE3065888D1 (en) | 1984-01-19 |
| FR2464932B1 (en) | 1982-06-04 |
| EP0025732B1 (en) | 1983-12-14 |
| JPS6317800B2 (en) | 1988-04-15 |
| EP0025732A3 (en) | 1982-02-10 |
| EP0025732B2 (en) | 1986-09-24 |
| FR2464932A1 (en) | 1981-03-20 |
| JPS5641894A (en) | 1981-04-18 |
| US4356768A (en) | 1982-11-02 |
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