EP0526317A1 - Telescopic ammunition cartridge - Google Patents

Abstract

The invention relates to a munition, in particular of the telescoped type, comprising a plastic case consisting of a cylindrical casing (2) and two plugs respectively front (4a) and rear (4b) located at the two ends of the casing , a projectile and a propellant charge housed inside the case, and a device for igniting the propellant charge, the invention is characterized in that at least one of the plugs (4a, 4b) forms a single piece coming molding with a cylindrical part (3a, 3b) of the casing (2) and integrated axial expansion means are located in the vicinity of the transition zone between the cylindrical part (3a, 3b) of the casing and the plug associated (4a, 4b). The invention is particularly applicable to small and medium caliber ammunition. <IMAGE>

Description

The present invention relates to a munition, in particular of the telescoped type, comprising a plastic case consisting of a cylindrical casing and two plugs respectively front and rear located at the two ends of the casing, a projectile and a propellant charge housed at inside the case and a propellant charge ignition device.

In general, it is known to design telescoped munitions whose front and rear plugs translate under the effect of the pressure of the gases so as to come into contact with the chamber of the barrel of the barrel during the initiation of propellant charging.

In patent US-4691638, there is described a munition in which the plugs are metallic and fixed to each end of the casing of the case. These plugs translate under the effect of the gas pressure without being able to exceed a stop pin carried by the casing of the case so as to remain linked with the latter to facilitate the extraction of the case after the shot. In order to avoid any jamming inside the chamber, vents fitted on the casing are released by the movement of the plugs.

The drawback of such a solution is that it breaks the confinement of the gases and brings the latter into contact with the internal surface of the chamber (blow of the torch), which has the effect of rapidly deteriorating the latter.

In the ammunition described in documents US-4907510, US-4846069 and EP-0328016, the envelopes and the plugs are also metallic, and elastic means are provided to allow, after firing, to return the cases to dimensions allowing their extraction from bedroom.

It is also known to use plastics to make the case of the ammunition, because the elasticity of these materials facilitates the extraction of the case after firing. However, the expansion coefficients are such that they cause significant length variations for the case (of the order of 1% for the entire temperature range). It is therefore essential to provide sufficient axial clearance between the case and the chamber.

In document US-4770098, there is described an ammunition whose case is made of plastic. More specifically, the rear plug, corresponding to the base of the ammunition, came from molding with the envelope, and the front plug is fitted tight in the free end of the case. However, the problems of expansion of the case inside the chamber during the projectile firing operation are not mentioned.

Indeed, the increase in pressure inside the case during the firing of the ammunition will bring the cylindrical part of the case in contact with the internal cylindrical surface of the chamber, preventing any translation of the case compared to the latter.

The pressure exerted on the rear cap will then cause the case to rupture at the transition zone between the cylindrical case and the rear cap, that is to say the zone at which the internal diameter of the case is reduced.

Patent EP328016 describes a telescoped munition comprising a case made of material with high mechanical resistance. The case has a groove disposed substantially at its median part. This groove has the function of ensuring after firing a return of the holster to its initial axial dimensions which makes it possible to avoid significant efforts during movements of the chamber of the weapon, efforts due to the permanent deformation that risk to present such materials.

The object of the invention is to design an ammunition of the telescoped type with a plastic case designed in a different way and equipped with means which allow it in particular to be able to expand axially during the firing of the ammunition.

Thus the subject of the invention is an ammunition, in particular a telescoped ammunition, comprising a plastic case consisting of a cylindrical envelope and two plugs respectively front and rear located at the two ends of the casing, a projectile and a propellant charge housed inside the case, and a device for igniting the propellant charge, ammunition characterized in that at least one plugs form a single piece molded with a cylindrical part of the envelope, and integrated axial expansion means are located in the vicinity of the transition zone between the cylindrical part of the envelope and the associated plug.

According to a particular embodiment, the case may be formed from two elements.

In general, the front plug may be in the form of a ring obtained by an internal excess thickness of the cylindrical part of the envelope associated with the case element, the internal wall of the ring connecting to the wall. internal part of the envelope by a frustoconical bearing.

The rear plug may be in the form of a base obtained by an internal excess thickness of the part of the envelope associated with the case element, the internal wall of the base being connected to the internal wall of the envelope by a frustoconical bearing.

Examples of axial expansion means will be given later, but generally they are located in the vicinity of a transition zone between the plugs and the cylindrical part of the case considered. That is to say that they can be located either at the level of the transition zone itself (zone at the level of which the internal diameter of the case is reduced), or at the level of the plugs themselves.

In fact, the envelope of the case sticks to the internal wall of the chamber of the barrel tube after initiation of the propellant charge, an axial expansion of the case can only occur in the vicinity of the front and rear plugs.

The configuration in which the case is formed of two elements (or half cases) according to one of the abovementioned embodiments also has the advantage of facilitating the loading of the ammunition. Indeed, we can set up the projectile relative to a half holster, then introduce the propellant charge into each half holster before assembling the two half holsters thus loaded to each other.

Depending on the case, we can adopt an agglomerated load for a half-case and a grain load for the other half-case, or an agglomerated load in each half-case. As a variant, it is possible to adopt two grain loads, but then at least one retaining washer will be provided to allow the two half-cases to be secured, so as not to reverse the load. The washer will preferably be made of a combustible material, such as nitrocellulose or else paper, or alternatively of a material which can be fragmented during firing.

• la figure 1 est une vue en coupe axiale de l'étui d'une munition télescopée conforme à l'invention suivant un mode de réalisation,
• la figure 2 est une vue en coupe axiale de l'étui d'une munition télescopée conforme à l'invention suivant un autre mode de réalisation,
• la figure 2a est une vue en coupe transversale d'une variante du mode de réalisation de la figure 2,
• la figure 3 est une vue en coupe axiale de l'étui d'une munition télescopée conforme à l'invention illustrant un autre mode de réalisation sur chacune des deux demi-vues de gauche et de droite,
• la figure 3a est une vue en coupe axiale partielle de l'étui d'une munition télescopée conforme à l'invention pour illustrer un perfectionnement apporté au mode de réalisation de la demi-vue de gauche de la figure 3,
• la figure 4 est une vue en coupe pour illustrer un autre mode de réalisation de l'étui d'une munition télescopée conforme à l'invention,
• la figure 4a est une vue en coupe axiale partielle de l'étui d'une munition télescopée conforme à l'invention illustrant un perfectionnement du dernier mode de réalisation de la figure 4.
• la figure 5 est une vue en coupe pour illustrer un autre mode de réalisation de l'étui d'une munition télescopée conforme à l'invention,

Other advantages, characteristics and details of the invention will emerge from the explanatory description which follows, given with reference to the appended drawings given solely by way of example and in which:

• FIG. 1 is a view in axial section of the case of a telescoped munition according to the invention according to one embodiment,
• FIG. 2 is a view in axial section of the case of a telescoped munition according to the invention according to another embodiment,
• FIG. 2a is a cross-sectional view of a variant of the embodiment of FIG. 2,
• FIG. 3 is a view in axial section of the case of a telescoped munition according to the invention illustrating another embodiment on each of the two left and right half-views,
• FIG. 3a is a partial axial section view of the case of a telescoped munition according to the invention to illustrate an improvement made to the embodiment of the left half-view of FIG. 3,
• FIG. 4 is a sectional view to illustrate another embodiment of the case of a telescoped munition according to the invention,
• FIG. 4a is a partial axial section view of the case of a telescoped munition according to the invention illustrating an improvement of the last embodiment of FIG. 4.
• FIG. 5 is a sectional view to illustrate another embodiment of the case of a telescoped munition according to the invention,

Referring to Figure 1, the representation of a telescoped munition 1 has been deliberately limited to its cylindrical casing 2, which is here formed of two elements 2a and 2b. These elements are assembled and made integral (for example by ultrasonic welding) after placing the projectile and the propellant charge (not shown) inside the envelope.

The ammunition also includes two plugs, a front plug 4a and a rear plug 4b.

In the following, we will consider that each of the two elements 2a and 2b constitutes a half case. Each half-case comprising a cylindrical part 3a, 3b, each cylindrical part being associated with a plug 4a, 4b.

The half-case 2a has a cylindrical part 3a open at one end. Towards the other end of the part 3a, the case 2a has a front plug 4a in the form of a ring 5a coming from molding with the part 3a. This ring 5a situated in the extension of the part 3a is formed by an additional thickness of the internal wall of the part 3a. Generally, the internal wall of the ring 5a is connected to the internal wall of the associated part 3a by a frustoconical bearing 6a.

The ring 5a is intended to receive a projectile (not shown), the positioning of which is described in particular in documents FR-2647890 and FR-2647891.

The half-case 2b has a cylindrical part 3b with a diameter equal to that of the part 3a of the half-case 2a. This part 3b is open at one end and closed at its other end by a rear plug 4b in the form of a base 5b which constitutes a bottom wall of the part 3b. This base 5b came from molding with part 3b. The internal wall of the base 5b is also connected to the internal wall of the part 3b associated by a frustoconical bearing 6b.

The two half-cases 2a and 2b, axially aligned with their open ends facing each other, are fixed to each other by any suitable means, such as by welding, with possible partial overlapping of the two parts 3a and 3b of the envelope. Of course, this linking operation is carried out after installation in the two half-cases 2a and 2b of the projectile and of the propellant charge, as has already been specified previously.

The base 5b is pierced with a central opening 5c in which is mounted an ignition device, known per se and not shown, of the propellant charge.

The two half-cases 2a and 2b also include axial expansion means which will be the subject of several embodiments given by way of example and described below.

Still referring to FIG. 1, these axial expansion means consist of a particular shape given to each half-case 2a and 2b. More specifically, in the example considered here, the reserve of material at the level of the half-case 2a results from an inward curving 7a of the part 3a of the envelope to form an internal annular bead 8a and an annular groove external 9a.

In order to avoid any break during the pressure build-up, this curvature 7a will be located at the transition zone between the part 3a and the associated plug 4a. Similarly, the half-case 2b has a curvature 7b located in the vicinity of the rear plug 4b and which delimits an internal annular bead 8b and an external annular groove 9b.

The two bends 7a and 7b can be filled with two rubber seals 10a and 10b respectively. These seals give the ammunition 1 a smooth external appearance which favors its positioning in the chamber of a weapon.

Concretely, once the ammunition is housed in the chamber of the weapon, the initiation of the propellant charge generates such pressure inside the half-cases 2a, 2b that they will expand both radially and axially. By expanding radially, the cylindrical parts 3a and 3b of the envelope come to stick against the internal wall of the chamber, which prevents any axial expansion at this level. On the other hand, the material reserves formed by the curvatures 7a and 7b situated towards the two ends of the half-cases 2a, 2b allow them to expand axially.

In the absence of these reserves, the result would be a rupture of each half case at the level of the transition zone between the cylindrical parts and the plugs.

Such a rupture makes it difficult to remove the case from the ammunition after firing the projectile.

There will now be described other embodiments of these expansion means which, like that illustrated in FIG. 1, are obtained by particular shapes given in the case.

According to an embodiment illustrated in Figure 2, the axial expansion means are formed at the half-case 2a by an annular groove 12a provided at the outer periphery of the ring 5a. This groove 12a is advantageously located in the vicinity of the frustoconical bearing 6a which connects the ring 5a to the part 3a of the envelope. The edges of the groove 12a are flared so that the introduction of the case of the ammunition is done without snagging inside the barrel tube chamber, without it being necessary to fill the groove 12a with a rubber filling.

As a variant of this embodiment, as illustrated in FIG. 2a, axial reinforcement ribs 13a can be provided inside the groove 12a to increase the bending stiffness of the half-case 2a and to ensure in addition to correct holding of the projectile inside the half-case 2a, without however affecting the elongation of the half-case 2a.

Similar axial expansion means are for example provided for the half-case 2b in the form of a groove 12b at the external periphery of the base 5b.

According to the embodiment illustrated in the left half-view of FIG. 3, the axial expansion means are formed by an annular space 15a provided in the ring 5a. This space 15a extends substantially over the entire length of the ring 5a and it opens out inside the part 3a.

Overall, the ring 5a comprises an external annular wall 5a1 which extends the cylindrical part 3a and has the same thickness as the latter, and an internal annular wall 5a2 substantially of the same thickness as the zone 5a1. With such a variant, the gas pressure can be exerted through the space 15a in the vicinity of the front face of the half-case 2a.

Thus, the elongation of the half-case can be distributed over its entire length, which avoids breaking at the level of the transition zone between the plug 4a and the part 3a of the envelope.

According to the variant illustrated in the right half-view of FIG. 3, the axial expansion means are constituted at the level of the ring 5a by several annular grooves 16a external to the ring 5a, delimited by surfaces substantially parallel to the frustoconical bearing 6a and separated by fins 16. These fins 16 give the half-case 2a a cylindrical external shape and allow a gradual radial deformation of the ring 5a at the level of the annular grooves 16a during the increase in pressure, therefore an axial deformation of the half -case.

The configurations described here with reference to FIG. 3 make it possible to have a substantially uniform material thickness, which ensures better homogeneity of the case during its manufacture by injection.

The axial expansion means at the base 5b of the half-case 2b are for example constituted by a groove 12b as in the embodiment of Figure 2. Indeed and in general, the axial expansion means are not necessarily the same at the level of the ring 5a and of the base 5b.

According to the embodiment illustrated in FIG. 4, the annular space 15a in the ring 4a of the half-case 2a corresponding to the previous embodiment is replaced by parallel channels 17a with circular section.

These channels each open into the interior of the envelope through an opening 18a which is located at the frustoconical surface 6a which connects the internal wall of the ring 5a and the cylindrical part 3a of the envelope.

It is thus possible to strengthen the rigidity of the internal wall 5a2 of the ring 5a and thus ensure better retention of the projectile inside the case.

The axial expansion means at the level of the base 5b of the half-case 2b are for example also constituted by parallel channels 17b which each open out through an opening 18b at a frustoconical surface 6b which connects the internal wall of the base 5b and the cylindrical part 3b of the envelope.

As a variant of this embodiment of FIG. 4a, the channels 17a can have a rectangular or oblong section to increase the surface of the openings 18a and thus decrease the surface of the frustoconical surface 6a on which the pressure will be exerted. This limits the risk of rupture between the part 3a of the casing and the ring 5a during the pressure build-up inside the case following the initiation of the propellant charge.

These embodiments of FIGS. 4 and 4a are also well suited to injection manufacturing since the thicknesses of material can be substantially uniform.

In the embodiments of FIGS. 3a (half-view on the left) and 4a, provision is made to incorporate into the half-case 2a an anti-wear supplement 20 such as a mixture of titanium dioxide and wax to limit wear of the barrel tube chamber. This mixture is pushed out of the case by the pressure of the gases when the projectile is ejected.

In FIG. 3a, the mixture 20 is placed at the bottom of the space 15a provided in the ring 5a, and there are openings 31 in the internal wall 5a2 of the ring 5a to allow the mixture 20 to be pushed out of the case 2 by the pressure of the gases as soon as the projectile is ejected from the ammunition 1.

The projectile closes the openings 31 when it is in place in the case of the ammunition 1. Optionally, the space 15a will be closed, at the level of its communication with the interior of the half-case 2a, by a closing straw. to avoid the mixture 20 from combining with the propellant change.

In FIG. 4a, the mixture 20 is placed at the bottom of each of the channels 17a of the ring 5a, and there is provided at the bottom of each of these channels 17a an inclined passage 33 which opens to the outside and to the front of ring 5a. These passages 33 are closed by a closing disc (not shown) fixed to the front of the ring 5a, this disc ejects during the pressure build-up.

As in the case of FIG. 3a, a closure spangle can be provided at the level of the openings 18a through which the channels 17a open out inside the half-case 2a. As a variant, these passages 33 can be radial openings as in the case of FIG. 3a.

The invention can also be applied to a munition comprising a single case closed by a plug.

FIG. 5 shows such ammunition in which the casing 2 carries at its front part a plug 5a which is capable of translating under the effect of the pressure of the gases.

The rear plug 5b is formed in one piece with the casing 2 and axial expansion means are provided at the transition zone between the casing 2 and the plug 5b. These means are of the type described with reference to FIG. 1, they include curvatures 7a and 7b delimiting an annular bead 8b and an external groove 9b.

The plug 5a is positioned on the envelope after the propellant charge has been placed inside the latter. It will carry the projectile, the installation of which is described with reference to the patents FR2647890 and FR2647891.

When the propellant charge is ignited, the pressure of the gases causes the envelope, which sticks against the internal wall of the chamber, to expand. The pressure also pushes the front plug 5a which translates relative to the envelope. It also pushes the rear plug 5b, the movement of which is authorized by the axial expansion means provided at the level of the transition zone between the envelope and the plug.

It would obviously be possible to design such a case by adopting expansion means of the type described with reference to FIGS. 2 to 4.

It would also be possible to design a case in which the rear plug would be able to translate relative to the envelope while the front plug would be formed in one piece with the envelope.

The expansion means will then be arranged at the transition zone between the envelope and the front plug and may be chosen from the examples described above.

The materials used in the context of the preceding variants are plastics of the thermoplastic type such as polycarbonates.

Finally, if the plastic material used to make the two half-cases can allow the elongation without breaking the case, which requires a relatively rigid material in the range of operating temperatures (-40 ° C, + 60 ° C) but which exhibits a high rate of elongation when it is subjected to significant stresses during firing, it is then possible to eliminate the axial expansion means described above, the plastic material by its sole properties allowing the axial expansion of the case.

A material of the thermoplastic elastomer type may be used. These materials are elastomers, that is to say that they are capable of deforming under stress without variation in volume and of recovering approximately their initial dimensions when the stress ceases (practically the elongation at break is greater at 300%). But they are qualified as thermoplastics because for reduced stresses, their tension / elongation curve is closer to that of thermoplastics (such as polycarbonates) than traditional elastomers.

Among the materials of this type, it is possible for example to adopt copolymers based on polyurethane (such as ESTANE or DESMOPAN, registered trademarks), based on polyester (such as HYTREL by Du Pont or ARNITEL by Akzo , Trademarks) or based on polyamide (such as DYNIL or PEBAX from Atochem, Trademarks).

Of course, the invention is not limited to the embodiments described above, and it includes all the technical means equivalent to those which have been given only by way of example with reference to the accompanying drawings. In particular, the same munition may have different axial expansion means for each element constituting its case, these means being chosen from those given by way of example.

The same munition can have axial expansion means according to the invention only at the level of one of the elements constituting its case, the other element being able to be designed differently. The separation between the two half-cases can be located more or less close to the front and rear caps.

Claims (15)

1- Ammunition, in particular telescoped ammunition, comprising a plastic case consisting of a cylindrical envelope (2) and two plugs respectively front (4a) and rear (4b) located at the two ends of the envelope, a projectile and a propellant charge housed inside the case, and a propellant charge ignition device, characterized in that:
at least one of the plugs (4a, 4b) forms a single piece molded with a cylindrical part (3a, 3b) of the envelope (2),
integrated axial expansion means are located in the vicinity of the transition zone between the cylindrical part (3a, 3b) of the envelope and the associated plug (4a, 4b). 2- Ammunition according to claim 1, characterized in that the case is formed of two elements (2a, 2b). 3- Ammunition according to claim 2, characterized in that the front plug (4a) is in the form of a ring (5a) obtained by an internal thickness of the cylindrical part (3a) of the envelope associated with the element case (2a), the internal wall of the ring (5a) connecting to the internal wall of the part (3a) of the envelope by a frustoconical bearing (6a). 4- Ammunition according to claim 2, characterized in that the rear plug (4b) is in the form of a base (5b) obtained by an internal excess thickness of the part (3b) of the envelope associated with the element d 'case (2b), the inner wall of the base (5b) connecting to the inner wall of the envelope (3b) by a frustoconical bearing (6b). 5- Ammunition according to one of claims 1 to 4, characterized in that the axial expansion means consist of a reserve of material resulting from a curvature (8a, 8b) towards the inside of the part (3a, 3b) of the envelope to form an internal annular bead (9a, 9b) and an external annular groove (7a, 7b). 6- Ammunition according to claim 5, characterized in that the annular groove (9a, 9b) is filled with a rubber seal (10a, 10b). 7- Ammunition according to one of claims 1 to 4, characterized in that the axial expansion means consist of a groove (12a, 12b) provided on the external surface of the plug (4a, 4b). 8- Ammunition according to one of claims 1 to 4, characterized in that the axial expansion means consist of an annular space (15a) provided in the plug (4a, 4b) and which opens into the part (3a, 3b) of the envelope associated with the case element (2a, 2b). 9- Ammunition according to one of claims 1 to 4, characterized in that the axial expansion means are constituted by parallel channels (17a) provided in the plug (4a, 4b) and which open into the part (3a, 3b) of the envelope by openings (18a) located at the level of the frustoconical bearing (6a, 6b) of the plug (4a, 4b). 10- Ammunition according to one of claims 1 to 4, characterized in that the axial expansion means consist of annular grooves (16a) fitted to the external surface of the plug (4a, 4b), delimited by surfaces substantially parallel to the frustoconical bearing (6a) and separated by fins (16). 11- Ammunition according to claim 8, characterized in that an anti-wear booster (20) is housed in the space (15a) of the front plug (4a) which communicates with the outside through openings (31) to allow at the top-up (20) to escape under the effect of the gas pressure. 12- Ammunition according to claim 11, characterized in that the openings (31) are located in the internal wall (5a2) of the front plug (5a), openings (31) which are closed by the projectile as long as it is not not ejected. 13- Ammunition according to claim 9, characterized in that an anti-wear supplement (20) is housed in the channels (17a) of the front plug (4a) which communicate with the outside via passages (33) to allow the extra (20) to escape under the effect of the gas pressure. 14- Ammunition according to claim 13, characterized in that the passages (33) open at the front of the plug (4a) are closed by a closing disc ejected during the pressure build-up. 15- Ammunition according to one of claims 1 to 4, characterized in that the material constituting the case is of the thermoplastic elastomer type, material which is used as a means of axial expansion.

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