EP0773425B1 - Means for lining retention for a hollow charge - Google Patents

Description

The technical field of the invention is that of devices for maintaining the coating of a load nucleus generator and more particularly of a charge core generator intended to be placed in inside a vector, like a cargo shell, and to be ejected out of it at a given time on trajectory

Core generating charges generally include an explosive charge placed in an envelope and on which is applied a coating having the overall shape of a spherical cap.

When the explosive detonates, the coating is set in motion by the incident pressure wave. It is deforms by turning "in a glove", that is to say that it turns into a projectile (or nucleus) whose front part is formed by the axial area of the covering and the rear part is a skirt formed by the periphery of the coating.

Patent FR2627580 describes such a generating charge of nucleus.

The coating is usually attached to the load explosive by bonding or it is immobilized in relation to the load envelope by means of a support integral with the envelope and placed in front of the covering.

Such known solutions are described by patents FR2657156 and EP543072, the latter serving as the basis for preamble to the main claim.

The installation of a support in front of the covering has the major drawback of disrupting training of the kernel by loading. This disturbance is present even by adopting a support such as that described by FR2657156 which dissociates itself from the envelope by the action of detonation of the explosive charge.

The support described by EP543072 causes deformations of the coating which may affect its stability.

In addition, the nucleus-generating charges which are intended to be ejected from a vector are subject to significant acceleration efforts that can cause, separation of the coating and the load, or any at least one degradation of the coating, thus adversely affecting the subsequent nucleus formation.

The problem of the behavior of the coating acceleration is all the more complex as the load in principle submitted when firing the vector (such as a artillery shell) at first acceleration, then knows during the ejection of the load out of the vector a second acceleration having a direction opposite to that of the first.

It is thus not possible to give the charge a orientation inside the vector which ensures in all case the resistance to acceleration constraints, of the coating as well as the explosive charge to which it is applied.

These loads are finally subjected during storage to thermal stresses which cause expansion including the amplitude is different for the explosive charge and for the metal casing.

It is the object of the invention to propose a device for maintaining the coating of a core-generating charge which overcomes such drawbacks.

The device according to the invention thus ensures a excellent resistance of the load to stress of acceleration undergone by it inside the vector without disturbing the formation of the nucleus.

This maintenance is also ensured whatever the thermal stresses suffered.

Thus, the subject of the invention is a holding device of a coating of a core-generating charge with respect to to an envelope of said charge, a charge which is intended for be placed inside a vector, such as a shell cargo, and to be ejected from this vector at an instant given on trajectory, device comprising means of wedging which ensures axial retention of the coating by load envelope, device characterized by what the wedging means are kept applied to the coating by means of support which is external to the load and which is ejected out of the vector at the same time as the latter, the wedging means separating from the load during of its ejection from the vector.

The support means may be constituted by another charge placed in the vector.

According to an alternative embodiment, the wedging means will also be able to ensure the rotational drive of the coating.

According to a characteristic of the invention, the means of wedging have a washer or an annular support which is supported on a peripheral area of the coating.

This washer or support can be divided into at minus two parts that separate when the ejection of the load out of the vector.

According to a particular embodiment, the washer may have spring tabs, regularly angularly distributed and which are arranged so as to allow compression deformation of the washer.

The spring tabs may have a shape of arcs of circle concentric with the washer.

According to another variant of the invention, the means of wedging may include a cup kept applied on an external surface of the coating.

A sheet of compressible material may be placed between the coating and the cup.

• la figure 1 représente schématiquement un vecteur renfermant deux sous-munitions à charge génératrice de noyau et incorporant un dispositif de maintien selon un premier mode de réalisation de l'invention,
• la figure 1a représente le même vecteur au moment de l'éjection des sous-munitions,
• la figure 2a, 2b et 2c représentent plus en détail le moyen de calage mis en oeuvre à la figure 1, la figure 2b étant une coupe suivant le plan AA dont la trace est représentée à la figure 2a, et la figure 2c montre une variante de réalisation,
• la figure 3a représente partiellement un vecteur renfermant deux sous-munitions à charge génératrice de noyau et incorporant un dispositif de maintien selon un deuxième mode de réalisation de l'invention,
• la figure 3b représente une variante de réalisation de la figure 3a,
• la figure 4a représente partiellement un vecteur renfermant deux sous-munitions à charge génératrice de noyau et incorporant un dispositif de maintien selon un troisième mode de réalisation de l'invention,
• les figures 4b et 4c montrent la rondelle ressort utilisée dans ce troisième mode de réalisation, la figure 4c étant une coupe suivant le plan repéré BB sur la figure 4b,
• les figures 5a et 5b représentent une variante d'exécution de la rondelle ressort,
• la figure 6 montre une autre variante de réalisation de la rondelle ressort,
• la figure 7 représente une variante de réalisation de la coupelle de calage.

The invention will be better understood on reading the description which follows of particular embodiments, description made with reference to the appended drawings and in which:

• FIG. 1 schematically represents a vector containing two submunitions with a core-generating charge and incorporating a holding device according to a first embodiment of the invention,
• FIG. 1a represents the same vector at the time of ejection of the submunitions,
• Figure 2a, 2b and 2c show in more detail the timing means used in Figure 1, Figure 2b being a section along the plane AA, the trace of which is shown in Figure 2a, and Figure 2c shows a variant of achievement,
• FIG. 3a partially represents a vector containing two submunitions with a core-generating charge and incorporating a holding device according to a second embodiment of the invention,
• FIG. 3b represents an alternative embodiment of FIG. 3a,
• FIG. 4a partially represents a vector containing two submunitions with a core-generating charge and incorporating a holding device according to a third embodiment of the invention,
• FIGS. 4b and 4c show the spring washer used in this third embodiment, FIG. 4c being a section along the plane marked BB in FIG. 4b,
• FIGS. 5a and 5b represent an alternative embodiment of the spring washer,
• FIG. 6 shows another alternative embodiment of the spring washer,
• Figure 7 shows an alternative embodiment of the wedging cup.

If we refer to Figure 1, a vector 1 which is here an artillery cargo shell, has a closed envelope 2 at one end by a base 3 and at the other end by a warhead 4.

Envelope 2 here contains two anti-tank submunitions 5a, 5b, which are held axially between the base 3 and a piston 6.

This shell is intended to eject at a given time on trajectory of the submunitions 5a and 5b. The ejection is controlled by a chronometric rocket 7, which initiates a gas generating charge 8. The gas pressure pushes the piston which causes the separation of the base 3 and envelope 2 then the exit of submunitions 5a, 5b out of the envelope.

Such a shell is known for example from the patent FR2682754, which shows in particular the means allowing the rotational drive of the submunitions by the envelope as well as those allowing an adjustment of the axial clearance between the submunitions and the envelope (means which are not shown here).

The submunitions 5a and 5b are generating charges of nucleus. Each load thus includes an envelope 10 to inside which an explosive charge is placed 9. A coating 11 is applied to the explosive charge 9.

Such a charge is described for example by the patent FR2627580.

According to a first embodiment of the invention, the coating is kept applied axially on the load explosive by wedging means which include a support annular 12.

This annular support is shown in more detail in Figures 2a and 2b. It has a smaller outer diameter or equal to the diameter of the shell 2 of the shell and on which there is a groove 13 intended to cooperate with a key (not shown) to ensure its training in rotation by the envelope 2.

The support 12 has a circular internal fold 14 which has a surface corresponding to the external surface of the coating 11. It also has a flat rear face 15 which is supported on the second load 5b and a flat edge 16 which comes to bear on the casing 10 of the load 5a.

When the two loads are mounted in the enclosure 2 shell as shown in Figure 1, the support 12 is found pinched between the two charges 5a and 5b. He then ensures axial retention of the coating 11 relative to the envelope 10 of the load 5a (as well as an axial maintenance of the load explosive 9 relative to the envelope 10).

The support is kept applied in this position of wedging of the covering by means of support which is formed by the second charge 5b.

FIG. 1a represents this same cargo shell 1 at the time of the ejection on the trajectory of the charges 5a, 5b.

The pressure of the gases generated by the generating charge of gas 8 separates the base 3 from the casing 2 of the shell and pushes in the direction marked by the arrow F stacking of charges outside the envelope 2.

The support 12 which is not integral with the loads 5a or 5b separates from these during ejection.

The nucleus-generating charge 5a then has the configuration, shown in Figure 1a, in which none ring or obstacle is not in front of the covering 11.

No disturbance is therefore to be feared during the nucleus formation.

Thanks to the invention, it is possible not to link the coating 11 to the load only by fixing means light and not very resistant, for example by gluing the coating on the explosive charge 9.

These fixing means do not have to resist the efforts due to the acceleration of firing of the shell (these efforts have here to apply the coating more firmly on the explosive).

They also do not have to resist the efforts due to acceleration of ejection of submunitions since, when this acceleration occurs (at the beginning of the ejection), the coating is maintained applied to the explosive charge by the holding device formed by the support 12.

The rotational drive of the coating by the shell will ensured by the contact of the support on the coating. He will be possible in case of need to provide small reliefs on the surface 14 of the support 12 in contact with the coating 11, this in order to allow a slight interconnection of these two elements.

Alternatively it is possible (as is shown in Figure 2c) to define a support 12 in which the internal circular fold 14 is replaced by three folds 14a, 14b and 14c regularly distributed angularly.

This variant will give some elasticity to the bond, possibly allowing compensate for thermal expansion.

Of course the coating of the load 5b is maintained axially by a similar support (not shown) arranged between the piston 6 and the load 5b.

As a variant, for this load 5b in contact with the piston 6, it is possible to give the piston a shape as it plays the role of support 12 itself.

Figure 3a shows a second embodiment of the invention in which the coating 11 of the load 5a is held axially relative to the casing 10 by wedging means constituted by a thin cup 17.

The cup 17 has a circular border 18 which is pinched between the two charges 5a, 5b and it has a curved profile which matches that of the external surface of the coating 11.

The cup will preferably be made of metal by example in steel or aluminum alloy.

An elastomer layer 19, for example silicone of a hardness from 50 to 60 shore A, is provided between the cup 17 and the coating to allow compensation for backlash thermal expansion.

The operation of this particular embodiment is similar to that previously described.

During the ejection of the charges 5a, 5b, the cup 17 is separates from the coating 11 as well as the elastomer 19 which may advantageously be glued to the cup.

The core charge of submunition 5a does not therefore no longer has any disruptive obstacle placed in front its coating.

This embodiment makes it possible to distribute the forces relatively uniform acceleration and on the entire outer surface of the covering 11. It is particularly well suited to loads generating core which use coatings whose material is ductile or for which the nucleus formation is disturbed by the presence of local constraints on the coating.

This embodiment also makes it possible to protect the external surface of the covering 11 of impacts or friction occurring at the time of ejection.

FIG. 3b shows an alternative embodiment in which the cup 17 is annular and therefore has a axial hole 20.

This embodiment makes it possible to give the cup a increased elasticity (possibly allowing to compensate for thermal expansions).

FIG. 4a shows a third embodiment of the invention in which the cup 17 does not include circular edge 18 but a flat support crown 21.

A washer 22 is placed on this support crown and comes between the load 5b and the cup 17.

In this embodiment, the timing means therefore include the cup 17 and the washer 22, and these wedging means are kept applied to the coating 11 by a support means which is constituted by the load 5b.

The washer has a diameter slightly larger than that of the envelope 10 and is housed in a counterbore 10a of the envelope. The counterbore carries dishes intended to cooperate with the washer to ensure its rotational drive.

The washer 22 is shown in more detail in Figures 4b and 4c. It is made of spring steel sheet stamped and it has spring tabs 23 (here four tabs), evenly distributed angularly, and which are supported on the crown 21 of the cup 17.

These spring tabs 23 have here the shape of arcs of circles concentric with the washer 22 and they are obtained by cutting the washer.

The washer 22 also has three flats 24, regularly distributed angularly, which cooperate with corresponding machining arranged on the casing 10 at the level counterbore 10a. These flats ensure the rotary drive of the washer 22 by the load 5a.

Thanks to the tongues 23, the washer 22 is deformable into compression and it makes it possible to make up for the axial clearances between the covering 11 and the covering 10, mainly the clearances due to thermal expansion.

When the coating is subjected to an accelerating force oriented towards load 5b (for example when load ejection), a slight axial displacement of the explosive charge carrying the coating occurs up complete crushing of the washer. This axial displacement is equal to the maximum thermal expansions encountered, it is of the order of 0.5 mm. Once crushed, the washer ensures (with the cup 17) the axial maintenance of the coating 11 and the explosive charge 9 relative to the casing 10 of the load.

When the acceleration forces are released, the tabs 23 bring back through the cup the coating and loading in contact with the bottom of the load (initial position of the load).

Once again, the cup allows the stresses to be distributed over the entire external surface of the coating.

When the charge is ejected from the shell, the washer 22 and cup 17 separate from the load 5a and therefore do not disturb the subsequent formation of the core.

The advantage of this embodiment is that it allows provide excellent mechanical resistance to acceleration load ejection while allowing expansion very reliably and reproducibly.

We will preferably adopt a washer 22 such that, when the shell is rotated, the ends of the tabs 23 engage in the cup 17 (or in the coating). This ensures the rotational drive of the cup and / or coating by the washer 22 (itself rotated by the casing 10 of the load). The use of a cup protects the coating from penetration of the tabs.

The washer must therefore be defined so that, the tabs come to rest on the cup and have a orientation such as the direction of rotation of the shell corresponds to an arc oriented from the base of the tongue towards its free end.

Alternatively we can replace the washer elastic 22 by a compressible elastomer washer.

Figures 5a and 5b show another variant of realization of the washer 22 in which the tongues spring 23 extend in a radial direction from the washer.

These tabs have a shape such that they come in contact with the concave surface of the cup 17.

As a variant, it is possible not to use cup and then provide a washer whose tabs spring come directly to bear on the covering (if the contact stresses on the coating the allow).

In order to facilitate the separation of the setting means and load it is possible to realize the cup 17 and / or the washer 22 in several sectors, these sectors can be made asymmetrically from so as to favor their dispersion out of the shell.

Figure 6 shows for example a spring washer 22 performed in four sectors 22a, 22b, 22c and 22d and the figure 7 shows a cup 17 made in three sectors 17a, 17b and 17c.

The embodiments of Figures 3 to 7 may well heard also to be used to maintain the coating and loading the load 5b. In this case the support means will be constituted for example by the piston 6.

It is finally possible to combine the different modes of realization described previously. For example by planning a spring washer interposed between the support 12 and the load 5b (figures 1, 1a), or between the border circular 18 of the cup 17 and the load 5b (figures 3a, 3b). In the variants of the Figures 1 or 4a, an elastomer layer 19 disposed between the coating 11 and the support 12 or the cup 17.

Claims (9)

1. A retention device for the liner (11) of a core generating hollow charge (5a) with respect to a casing (10) of said charge, such charge being intended to be positioned inside a vector (1), such as a carrier shell, and to be ejected from this vector at a given time during the trajectory, such device incorporating shimming means that ensure the axial retention of the liner (11) with respect to the charge casing (10), such device being characterised in that the shimming means are held against the liner (11) by bearing means outside of the charge (5a) and that are ejected out of the carrier at the same time as the charge itself, the shimming means separating from the charge when it is ejected from the vector.
2. A retention device according to Claim 1, characterised in that the bearing means are formed by another charge (5a) positioned in the vector.
3. A retention device according to one of Claims 1 or 2, characterised in that the shimming means also ensure that the liner (11) is driven in rotation.
4. A retention device according to one of Claims 1 to 3, characterised in that the shimming means incorporate a washer (22) or ring-shaped support (12) that presses on a peripheral zone of the liner (11).
5. A retention device according to Claim 4, characterised in that the washer (22) or ring-shaped support (12) is divided into at least two parts that separate during the ejection of the charge from the vector.
6. A retention device according to one of Claims 4 or 5, characterised in that the washer (22) incorporates spring tabs (23), evenly spaced angularly and arranged so as to enable the washer (22) to be deformed by compression.
7. A retention device according to Claim 6, characterised in that the spring tabs (23) are in the shape of arcs of a circle concentric to the washer (22).
8. A retention device according to one of Claims 1 to 7, characterised in that the shimming means incorporate a cupel (17) held against an outer surface of the liner (11).
9. A retention device according to Claim 8, characterised in that a sheet of compressible material (19) is placed between the liner (11) and the cupel (17).

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