EP2103896B1 - Flyer disk and slapper detonator without primary explosive comprising such a flyer disk - Google Patents

Description

The present invention relates to an improved paillet, intended to equip a detonator. The invention also relates to a detonator without primary explosive equipped with such a paillet.

FR 2,692,346 discloses a straw according to the preamble of claim 1.

The detonators with primary explosive have a very high reliability of operation, because the primary explosive can be put in regime explosive by a simple flame or by a mechanical shock. The major disadvantage of this type of detonator is that the primary explosive is unstable, so dangerous and delicate to handle.

Detonators without primary explosive use the impact of a projectile launched at high speed on a secondary explosive. The absence of primary explosive has the advantage of an increase in the safety of use, in particular a reduction in sensitivity to shocks and electrostatic discharges. Such a detonator also has the advantage of being able to be used at high temperatures. However, detonation of commonly used secondary explosives requires a minimum impact velocity greater than 500 m / s.

The object of the invention is to provide means for a detonator without primary explosive having improved reliability, in particular to ensure a sufficiently high impact speed.

According to a first object of the invention, such an objective is achieved by means of a detonator paillet according to claim 1.

Such an architecture of the straw provides a complete, clean and clean cut of the straw, that is to say an optimal separation between the projectile area and that ensuring the maintenance of the flail, and a safe ejection and high speed.

Preferably the flap comprises one or more of the features which are the subject of claims 2 to 10.

The invention also relates to a detonator according to claim 11. Other means, which are the subject of claims 12 to 19, may participate in improving the reliability of such a detonator.

Advantageously, the detonator comprises, between the spacer and a wall of the body with which the spacer is fitted, gas sealing means resulting from the combustion of said initiation powder. Such sealing means can confine these gases in the expansion chamber, so to reach a high pressure. It is thus possible to provide a high rupture pressure for the flail, which guarantees a high ejection speed for the projectile, and therefore a sufficient impact speed on the receiving explosive. Given the manufacturing tolerances, in particular the detonator and the explosive, a sufficient seal allows to have a significant margin between the speed of ejection and the minimum required speed. This margin makes it possible to ensure good reliability of the detonator. The sealing means may comprise at least one O-ring disposed in a groove of an outer wall of the spacer. They may comprise at least one metalloplastic seal.

The initiating powder may comprise at least one ignition powder. It may further comprise one or more gas-generating powders.

The receiving explosive is advantageously a secondary explosive, which gives it great stability and guarantees greater safety for a user when handling the detonator.

The firing system for the initiation powder may comprise a filament allowing the passage of an electrical pulse which allows the heating and firing of the initiation powder.

The firing system for the initiation powder may comprise optical fibers for guiding a laser beam, the impact of a light of a laser light for heating and firing the powder initiation.

Other features and advantages of the invention will emerge from the description below, relating to non-limiting examples.

• la figure 3 et une vue en coupe axiale d'une variante de réalisation du paillet des figures 2a et 2b ;
• les figures 4 à 7 sont des coupes axiales qui illustrent quatre autres modes de réalisation pour un paillet selon l'invention ;
• les figures 8 et 9 illustrent schématiquement deux modes de réalisation pour une cartouche de poudre d'initiation utilisable dans un détonateur selon l'invention ; et
• les figures 10 et 11 illustrent deux modes de réalisation pour un embout détonnant, qui diffère du mode de réalisation de la figure 1.

In the accompanying drawings:

• the figure 3 and an axial sectional view of an embodiment variant of the flail of Figures 2a and 2b ;
• the Figures 4 to 7 are axial sections that illustrate four other embodiments for a straw according to the invention;
• the Figures 8 and 9 schematically illustrate two embodiments for an initiation powder cartridge usable in a detonator according to the invention; and
• the Figures 10 and 11 illustrate two embodiments for a detonating tip, which differs from the embodiment of the figure 1 .

For the rest of the description, the front is arbitrarily defined as the right of the figure 1 .

The figure 1 represents a longitudinal section of a detonator 2 according to the invention. The detonator 2 is of substantially circular shape about a longitudinal axis X2. The detonator 2 comprises a hollow body 4 and a detonating tip 6. The body 4 serves as an assembly support for the various components of the detonator.

An initiation powder cartridge 8 is housed inside the body 4, close to an anterior zone 10 of the body 4. The cartridge 8 is mounted on a support 11 mounted fitted inside the hollow body 4.

The detonator 2 further comprises firing means 12 for an initiation powder contained in the cartridge. The firing means extend longitudinally in the body from the rear of the cartridge 8. In the example illustrated, the firing means are of the filament type 14, that is to say that they comprise a filament embedded in the powder and carried by electrodes extending from the cartridge towards the rear of the body.

The detonating tip 6 is mounted in an anterior zone 10 of the hollow body 4. It is immobilized axially between an inner shoulder 16 of the body 4 and a folded end 18 of the body 4, in front of the anterior zone 10. Anterior device 10 further comprises a cylindrical peripheral wall 19, inside which the detonating tip 6 is fitted.

The detonating tip 6 comprises, axially and from back to front, a washer 20, a flake 22, a spacer 24 and a cartridge 26 of receiver explosive, here a secondary explosive. The washer 20 is immobilized axially between the shoulder 16 and the flap 22. The flap 22 is immobilized axially between the washer 20 and the spacer 24. The spacer 24 is immobilized axially by crimping between the flap 22 and the folded end 18 of the body 4.

Advantageously, the parts 20, 22, 24 are assembled one with its neighbor by brazing, welding, or any other method to ensure gas tightness between these parts.

The shoulder 16 is disposed immediately in front of the initiation cartridge 8, so that an expansion chamber 28 is formed by the body, around the initiation cartridge 8, the cartridge holder 11, at the rear of the cartridge 8, as well as by the washer 20 and the straw 22 at the front of the cartridge 8.

The spacer 24 internally forms a cylindrical axial bore 30 of diameter D30. This bore opens out all its cross section at the rear of the spacer. The front of the bore comprises an annular bottom 31 in which opens a housing 32 for the secondary explosive. At its outlet in the bore, the diameter D32 of the housing 32 is smaller than the diameter D30 of the bore 30.

Thus, the housing 32 forms a forward cylindrical shrinkage of diameter D32, then tapers conically forwards to a front end of the spacer. The secondary explosive is kept confined in the housing 32, and, beyond, by a casing 34, folded over a front portion of the spacer which extends beyond the front end 18 of the body 4. L envelope 34 forms a front end of the detonator 2. The envelope allows the confinement of the secondary explosive cartridge. The envelope is here made of stamped metal.

The washer 20 has a bore of substantially the same diameter D30 as that of the bore 30 of the spacer 24.

The straw is substantially of revolution around an axis of straw X22. To the figures 1 and 2a , that is to say when the flap is mounted in the detonator 2, the axis X22 and the axis X2 are substantially merged. According to the invention, the straw 22 comprises a holding zone 38, a central zone 40 and an intermediate zone 46.

The holding zone 38 is substantially in the shape of an annular disc. It is peripheral to the intermediate and central zones.

The central zone 40 of the flap has the form of a hollow cylinder closed at its front end and whose outer diameter is substantially equal to the diameter D30 of the bore 30. Thus, the bore of the washer 20 and the bore 30 spacer 24 together form a barrel fitted around the central zone 40 of the flap 22. The central zone 40 has a convex front surface and a concave rear surface.

Finally, the intermediate zone 46 has the shape of a cylinder which is connected on one side to the cylindrical wall of the central zone 40 and the other to an inner peripheral edge of the holding zone 38. The radial thickness E46 of the intermediate zone 46 is smaller than the axial thickness E38 of the holding zone 38 and the radial thickness of the cylindrical wall of the central zone 40.

The glitter of the figure 3 differs from that of the figure 2a by the presence of sealing means 41 and 43, such as for example metal-plastic seals, arranged in grooves formed in the outer wall of the central cylindrical zone 40. The seals 41 and 43 make it possible to reinforce the tightness between the wall peripheral of the central zone 40 and the wall of the bore 30 and thus contribute to obtaining a high ejection speed of the central zone 40 of the flail.

We will describe the operation of the detonator with reference to the paillet figures 1 , 2a and 2b .

In the example of paillet illustrated at figure 1 the thickness E40 of the central zone 40 progressively increases from the periphery to the axis X22. The intermediate zone and the central zone together form a cylindrical surface facing towards the front of the detonator.

The least thickness of the intermediate zone 46 forms a rupture primer at the junction of the central zone 40 and the holding zone 38. In addition, the nip of the holding zone 38 between washer 20 and spacer 24 makes the junction the intermediate zone 46 with the holding zone 38 constitutes a possible shear zone for the flail.

During the combustion of the initiation cartridge 8, the combustion gases exert a strong pressure behind the central portion 40, causing shearing of the intermediate portion 46 as shown in FIG. figure 2b then the propulsion of the central portion 40 in the barrel formed by the bore 30. The central portion is thus transformed into a projectile 40 which will strike the bottom 31 of the bore. The percussion of the bottom 31 causes the explosion of the secondary explosive contained in housing 32 which leads to it. The shear failure of the flail from a certain pressure threshold allows high speed ejection of the projectile 40 formed by the central portion.

1. a) garantie d'une bonne étanchéité entre la zone centrale 40 formant projectile et la paroi intérieure de l'alésage 30 du fait des formes cylindriques conjuguées de la paroi extérieure de la zone centrale 40 et de l'alésage 30, ce qui permet de générer une pression élevée dans la chambre de combustion 28 de la poudre d'initiation et d'assurer ainsi la propulsion du paillet 40 à grande vitesse avec une marge importante par rapport au seuil nécessaire pour mettre en détonation la cartouche réceptrice d'explosif secondaire 26 ;
2. b) structure et système de montage avantageux du paillet permettant une découpe franche et homogène du paillet entre la zone de maintien 38 et la zone centrale 40 au niveau de la zone intermédiaire 46 ;
3. c) éviter les risques de basculement du projectile grâce à sa forme cylindrique lors de la propulsion dans le canon 30 : le basculement du paillet, possible si la zone centrale est par exemple en forme de pastille, peut conduire à un non fonctionnement du détonateur car la surface d'application de la pression devient plus réduite et la vitesse peut alors devenir insuffisante pour atteindre le seuil nécessaire pour mettre en détonation l'explosif secondaire récepteur ; en cas de basculement du paillet, la surface d'impact sur le récepteur est également plus réduite et risque de ne pas permettre la mise en détonation de l'explosif récepteur.
4. d) propulsion optimisée par l'onde de pression en amont du paillet ;

Such a configuration of the flail having a central cylindrical portion 40 connected to the holding portion 38 by an intermediate portion 46 of reduced thickness has the following advantages:

1. a) guaranteeing a good seal between the central zone 40 forming the projectile and the inner wall of the bore 30 because of the conjugate cylindrical shapes of the outer wall of the central zone 40 and the bore 30, which makes it possible to generate a high pressure in the combustion chamber 28 of the initiation powder and thus ensure the propulsion of the flail 40 at high speed with a large margin compared to the threshold necessary to detonate the secondary explosive receiver cartridge 26 ;
2. b) advantageous structure and mounting system of the flail allowing a frank and homogeneous cutting of the flake between the holding zone 38 and the central zone 40 at the intermediate zone 46;
3. c) avoid the risks of tilting of the projectile thanks to its cylindrical shape during propulsion in the barrel 30: the tilting of the flail, possible if the central area is for example in the form of a tablet, may lead to non-operation of the detonator because the application surface of the pressure becomes smaller and the speed may then become insufficient to reach the threshold necessary to detonate the secondary explosive receiver; in the event of tilting of the flap, the impact surface on the receiver is also smaller and may not allow detonation of the receiving explosive.
4. d) propulsion optimized by the pressure wave upstream of the paillet;

Sealing means 36 are arranged around the spacer, between the spacer and the peripheral wall 19. These sealing means are provided to prevent the gases from the combustion of the initiation cartridge from escaping from the device. detonator at the junction of the body and the spacer. Thus, the gases can only relax in the barrel, and they participate all in the propulsion projectile 40 from the rupture of the flap 22. The sealing means may be provided redundant. In the example shown in figure 1 , the sealing means comprise two O-rings, each disposed in a respective groove 44 formed in the spacer and the grooves being spaced axially from one another.

The Figures 4 to 7 illustrate alternative embodiments of the paillet figures 1 and 2a .

The part of the flail normally facing the front of the detonator when the flap is mounted there will be named "before the flail". All the straws described are of revolution around a respective pin axis X22.

• l'épaisseur E38 de la zone de maintien est sensiblement constante, de sorte que la zone de maintien vient en prise axiale entre la rondelle 20 et l'entretoise 24 ;
• l'épaisseur E40 de la zone centrale est plus grande que l'épaisseur E46 de la zone intermédiaire ;
• le diamètre extérieur de la zone centrale est sensiblement égal au diamètre intérieur D30 de l'alésage 30 formant canon.

For all the straws described on the Figures 4 to 7 :

• the thickness E38 of the holding zone is substantially constant, so that the holding zone engages axially between the washer 20 and the spacer 24;
• the thickness E40 of the central zone is greater than the thickness E46 of the intermediate zone;
• the outer diameter of the central zone is substantially equal to the inside diameter D 30 of the barrel bore 30.

Like those of Figures 2 and 2a , the straws Figures 4 and 7 also comprise between the holding zone 38 and the central zone 40, an intermediate zone 46 of substantially cylindrical shape extending between an inner edge of the holding zone and an outer edge of the central zone, that is to say of the projectile. This central zone 40 is also of substantially cylindrical shape in that it has at the periphery an axial length sufficient to avoid the risk of tilting in the bore 30. This significant axial length can be conferred by the axial thickness of the closed end of the central zone 40 or by a cylindrical tubular wall longer or shorter between this closed end and the holding zone 38 as in the case of the embodiment of the figure 2a .

In the position provided for mounting the flap in the detonator, the intermediate zone extends forward from the inner edge of the holding zone. The radial thickness E46 of the intermediate zone 46 is smaller than the thickness E38 of the holding zone 38, at the thickness E40 of the central zone 40 and, if it is extended rearward by a cylindrical tubular wall as indicated above, to the radial thickness of the cylindrical tubular wall. Intermediate zone 46 thus constitutes a privileged break zone. In addition, a break in the intermediate zone 46 preserves an outer edge of the projectile 40, which ensures its fit in the barrel 30 and a good seal around the projectile 40 during its ejection into the barrel. This zone makes it possible to ensure good flake cutting reliability by allowing a more uniform cutting. Thus, the gases resulting from the combustion of the initiation powder remain better confined to the rear of the projectile and provide optimized propulsion.

In the case of the glitter of the figure 4 the central zone 40 comprises a constant thickness E40, between two plane surfaces.

In the case of the glitter of the figure 5 the central zone 40 comprises a constant thickness E40, between two curved surfaces, one convex at the front, the other concave at the rear.

In the case of the glitter of the figure 6 analogous to that of figure 2 the central zone 40 comprises two curved surfaces, one convex at the front, the other concave at the rear. The thickness E40 of the central zone gradually varies by increasing as one approaches the axis X22.

In the case of the glitter of the figure 7 the central zone 40 comprises a flat rear surface, and the thickness of the central zone takes two values. In an area closest to the axis X22, the thickness E40 is greater than in the rest of the central zone 40.

In the case of the strawberry of the figure 7 , the diameter of the central portion of smaller diameter is less than or equal to that D32 of the secondary explosive cartridge 26, which increases the impact on the secondary explosive, so the reliability of the detonator. The same goes for the straws figures 2 , 5 and 6 , for which the bulging of the front surface of the paillet increases the impact on the secondary explosive.

A flake made of titanium alloy, steel or aluminum is preferably used. It can be achieved by electroerosion, stamping or any other method to ensure the required geometry and accuracy.

Two types of introductory cartridges will now be described with reference to Figures 8 and 9 .

In the example of the figure 8 there is a single ignition powder 50 as initiation powder, initiated by the filament 14, as also illustrated in FIG. figure 1 . In this example, the pressure wave is generated by the single ignition powder 50.

In the example of the figure 9 the cartridge contains two powders, an ignition powder initiated by the filament 14, and a gas generating powder 52. In this example, the pressure wave is generated essentially by the gas generating powder 52.

Two embodiments will now be described for detonating tips, with reference to Figures 10 and 11 , in that these embodiments differ from that of the figure 1 .

In the example of the figure 10 , a disbursement 60 is formed in the bottom 31 of the barrel 30. The diameter D60 of the disbursement is smaller than the diameter D30 of the barrel 30 and greater than the diameter D32 of the narrowing of the housing 32. the depth E60 of the disbursed is small relative to its diameter D60 . The disbursed is part of the housing 32 and is also filled with secondary explosive.

In the example of the figure 11 , a portion 62 of the secondary explosive is disposed on a thickness E62, behind the bottom 31 of the bore 30. The thickness E62 is small relative to its diameter D30.

Provisions such as those of Figures 10 and 11 , in which secondary explosive receiver occupies all or part of the bottom 31 of the bore 30 allow to have an impact surface 61 widened for the projectile. Nevertheless, this allows the confinement of a majority of the receiving explosive beyond the shrinkage.

Of course, the invention is not limited to the examples that have just been described and many adjustments can be made to these examples without departing from the scope of the invention.

Thus, other types of initiator powder firing system can be used. In particular, it is possible to use a laser beam system, guided to the optical fiber initiation powder cartridge.

The detonating tip can be assembled with the body by crimping, as described in the figures, or by other means, in particular by welding, brazing or screwing.

Other sealing means may supplement the O-rings or substitute them, in particular metal-plastic joints.

The body of the detonator may also be adapted so that the retaining washer is replaced by a retaining shoulder formed in the body.

Claims (19)

1. A flyer disc (22) for a detonator (2) according to which the flyer disc is formed to substantially revolve about a flyer disc axis (X22) and comprises a central zone (40) forming a projectile (40) and a holding zone (38) peripheral to said central zone, said zones (38, 40) being formed by a single piece, characterised in that the central zone (40) is substantially cylindrical in forum, in that the flyer disc further comprises an intermediate rupture zone (46) also substantially cylindrical in form extending towards the front between the inner edge of the holding zone (38) and the peripheral edge of the projectile (40), at least one of said central zone (40) and said intermediate rupture zone (46) being in the form of a hollow cylinder and in that the radial thickness (E46) of the intermediate zone (46) is less than the axial thickness (E40) of the central zone (40).
2. The flyer disc according to Claim 1, characterised in that the radial thickness (E46) of the intermediate zone (46) is less than the radial thickness of the cylindrical wall of the central zone (40).
3. The flyer disc according to either of Claims 1 to 2, characterised in that the radial thickness (E46) of the intermediate zone (46) is less than the axial thickness (E38) of the holding zone (38).
4. The flyer disc according to any of Claims 1 to 3, characterised in that the axial thickness (E38) of the holding zone is substantially constant.
5. The flyer disc according to any of Claims 1 to 4, characterised in that the projectile has a substantially constant axial thickness (E40).
6. The flyer disc according to any of Claims 1 to 4, characterised in that the projectile has an axial thickness (E40) that varies progressively by increasing as one moves closer to the axis (X22).
7. The flyer disc according to any of Claims 1 to 4, characterised in that the projectile comprises a number of coaxial parts, each part having a constant axial thickness which becomes larger as said part comes closer to the axis (X22).
8. The flyer disc according to any of Claims 1 to 7, characterised in that the projectile (40) has a convex front surface.
9. The flyer disc according to any of Claims 1 to 8, characterised in that the projectile (40) has a concave rear surface,
10. The flyer disc according to any of Claims 1 to 9, characterised in that said central zone (40) of the flyer disc comprises sealing means (41, 43) on its periphery.
11. A detonator (2) equipped with a flyer disc according to any of Claims 1 to 10.
12. The detonator according to Claim 11, characterised in that it comprises a body (4) and a brace (24) mounted by interlocking at the front (10) of said body,

    - said body carrying an initiation powder cartridge (8) and a firing system (12, 14) for said initiation powder,

    - said body and said brace forming between them an expansion chamber (28) for said initiation powder,

    - said brace carrying a receiving explosive cartridge (32),

    - said brace forming, between the flyer disc (22) and the receiving explosive cartridge, a barrel (30) for the projectile,

    - said flyer disc being mounted such that the projectile engages in said barrel and,

    - said flyer disc being mounted such that the holding zone (38) is pinched axially between a rear face of the brace and a front face of a washer (20) or a holding shoulder.
13. The detonator according to Claim 12, characterised in that it comprises between the brace and a wall of the body with which the brace is interlocked sealing means (36) for the gases produced by the combustion of said initiation powder.
14. The detonator according to Claim 13, characterised in that the sealing means comprise at least one O-ring joint (36) located in a groove (44) of an outer wall of the brace.
15. The detonator according to either of Claims 13 and 14, characterised in that the sealing means comprise at least one metallo-plastic joint.
16. The detonator according to any of Claims 12 to 15, characterised in that the initiation powder comprises at least one ignition powder (50).
17. The detonator according to Claim 16, characterised in that the initiation powder further comprises one or more powders that generate gas (52).
18. The detonator according to any of Claims 12 to 17, characterised in that the receiving explosive is a secondary explosive,
19. The detonator according to any of Claims 12 to 18, characterised in that the firing system for the initiation powder comprises optical fibres for guiding a laser beam.

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