EP2219007B1 - Method of fixing a plastic projectile on a metallic case and projectile permitting the application of said method - Google Patents

Description

The technical field of the invention is that of the projectiles having a plastic body and that of the methods of fixing such projectiles on a case.

Ammunition, regardless of caliber, includes a projectile and a case (or case) containing a propellant charge.

The case allows the firing of the ammunition from a weapon system. It thus has dimensions ensuring the placement of the projectile at the tube of the weapon. The case carries means for igniting the propellant charge and frequently performs the function of maintaining the seal with respect to the propellant gases during firing.

It is conventional to use cases made of metallic materials (steel or brass). The projectile is then fixed in a simple and fast manner on these cases by annular crimping. This operation is made possible by the presence on the projectile body of a groove in which it deforms the material of the case.

Today we are trying to make projectiles with non-lethal functions (smoke, tear ...) and shoot these projectiles from existing weapons systems.

Non-lethal projectiles have a body that is largely made of plastic, in order to reduce the risk of projection of vulnerable fragments to people. The material of the body is then less resistant than that of the case and it is no longer possible to fix the projectile to the case by crimping.

The patent application EP1914507 describes a means for attaching a projectile to a case in which the case is a specific case which has a front part on which the projectile is screwed and a rear part which encloses the propellant powder. The front and rear parts are separated by breaking primers that break during firing to release the projectile.

Such a solution is however not satisfactory because it requires the design of specific cases adapted to the projectile considered. This solution is not economically interesting. The cases are indeed metal components manufactured in large series and it is preferable to keep the same definition of case for all the ammunition of a given caliber.

The patent application GB 2 321 950 A describes a fixing method and a projectile according to the respective preambles of claims 1 and 4.

The object of the invention is to propose a fixing method making it possible to overcome such disadvantages.

Thus the method according to the invention makes it possible to fix easily and reliably on a metal case a projectile, whose body is made at least partly of plastic.

The subject of the invention is therefore a method of fixing a projectile on a metal case having a body at least partly made of plastic material, characterized in that the projectile is endowed with a rear extension separated from the body of the body. projectile by at least one means of rupture, the rear extension carrying or comprising a metal outer profile on which is arranged at least one groove, the case being fixed by crimping at this groove.

According to a particular mode of implementation, the external metal profile is constituted by a ring on which the case is crimped, the projectile being fixed in a second time to the ring by screwing its rear extension on the ring.

Advantageously, before crimping the case on the ring, it will position in this ring a holding rod made of a metal material more deformable than that of the ring.

More particularly, the invention also relates to a projectile whose structure is adapted to facilitate such fixing by crimping.

Thus, the invention relates to a projectile comprising a body at least partly made of plastic and intended to be fixed to a metal sleeve, projectile characterized in that it comprises a rear extension which is separated from the projectile body by at least a breaking means, the rear extension carrying or having an external profile cylindrical metal on which is arranged at least one crimping groove for receiving the case.

According to a particular embodiment, the rear extension is integral with the projectile body and made of plastic material, this extension carrying at least one metal ring having the crimping groove or grooves.

The breaking means may then comprise at least one zone of reduced thickness interposed between the extension and the projectile body, an area delimited by at least one circular groove.

Advantageously at least one metal reinforcing means may be arranged in the groove and secured to the extension.

The metal reinforcing means may be constituted by at least two half-rings.

The metal ring can be linked to the rear extension by threading.

According to another embodiment, the rear extension is made of a metallic material and fixed to the projectile body by screws, the cylindrical outer profile of this extension carrying the crimping groove or grooves.

The projectile according to the invention also has a satisfactory mechanical strength from the point of view of the constraints of storage and implementation.

• la figure 1 est une vue en coupe partielle d'une munition incorporant un projectile selon un premier mode de réalisation de l'invention,
• la figure 2 est une coupe transversale de la précédente, coupe réalisée suivant le plan dont la trace AA est repérée aux figures 1 et 3,
• la figure 3 est une vue de détail agrandie des moyens assurant la solidarisation du projectile et de l'étui,
• la figure 4 est une vue de détail agrandie d'un second mode de réalisation d'un projectile selon l'invention.

The invention will be better understood on reading the following description of particular embodiments, a description given with reference to the accompanying drawings and in which:

• the figure 1 is a partial sectional view of a munition incorporating a projectile according to a first embodiment of the invention,
• the figure 2 is a cross-section of the previous one, cut according to the plane whose track AA is Figures 1 and 3 ,
• the figure 3 is an enlarged detail view of the means ensuring the fastening of the projectile and the case,
• the figure 4 is an enlarged detail view of a second embodiment of a projectile according to the invention.

The Figures 1 to 3 show a munition 1 which comprises a case 2 and a projectile 3.

The case is made of metal for example steel while the projectile is a non-lethal projectile (for example containing a tear gas composition) and comprises a body 4 of which at least a portion is made of plastic.

Here is shown only the rear part of the projectile 3 which therefore comprises a bottom 4 of plastic (bottom receiving here a tracer 5).

According to the invention the bottom 4 of the projectile 3 comprises a cylindrical rear extension 6 delimiting an internal cylindrical cavity 11. This extension 6 comprises a thread on its outer surface 6a on which is screwed a metal ring 7.

The metal ring 7 comprises at least one crimping groove 8 at which can be fixed the case 2 by an annular crimping S.

The metal ring 7 (made for example of stainless steel) provides sufficient mechanical strength for crimping the case 2 steel. The case 2 comes into abutment when mounted on a shoulder 7a of the ring 7. This ensures a correct positioning of the ring 7 before crimping.

The different stages of mounting the projectile on the case will be specified later.

According to another characteristic of the invention, the extension 6 is separated from the bottom 4 (or body) of the projectile by at least one breaking means 9.

According to the embodiment which is represented here, the breaking means is constituted by a zone 9 of reduced thickness disposed between the extension 6 and the bottom 4, this zone 9 is delimited by a circular groove 10 (here at the bottom ring but this groove could have a cylindrical bottom).

The cylindrical cavity 11 of the extension 6 extends axially beyond the zone of reduced thickness 9.

When firing the ammunition, the propellant gas pressure is exerted on the bottom 4 of the projectile 3 and a tensile stress appears at the reduced thickness zone 9. This zone breaks and the projectile is ejected out the tube of the weapon while the extension 6 and the reinforcing ring 7 remain attached to the case 2, in the chamber of the weapon.

The metal ring 7 is not projected and no lethal effect is to be feared.

It is noted in the figures that half-rings 12a and 12b are housed in the groove 10. These half-rings are made integral with the extension 6 by screws 13. The half-rings 12a and 12b are metallic and constitute a reinforcement means the groove with respect to sudden stresses (falls, shocks, vibrations). They provide a setting of the projectile body 4 with respect to the extension 6 and prevent any bending at the rupture zone 9 during the transport and implementation phases of the munition. This avoids any premature weakening of the zone 9 and any deterioration of the ammunition before firing.

Note that the screws 13 are fixed at a collar 6b of the extension 6. Thus neither the screws 13 nor the half-rings 12a, 12b are attached to the bottom 4 of the projectile. If these reinforcement means protect the rupture zone 9 with respect to external stresses, they do not prevent the rupture of the zone 9 under the effect of the pressure of the gases exerted in the cylindrical cavity 11.

Different variants are possible without departing from the scope of the invention.

Here the reinforcement means were made in the form of two half-rings 12a, 12b which facilitates the assembly of this means at the groove 10. It would of course be possible to replace the half-rings 12a, 12b with simple nuts connected to each screw 13 or by half-rings having grooves coming to cap the collar 6b of the extension 6 (which allows to remove the screws).

The invention also relates to a method of fixing on a metal case of a projectile having a body at least partly made of plastic.

According to this method, the projectile is provided with a rear extension separated from the projectile body by at least one breaking means, and then the case is fixed by crimping on this rear extension.

To allow crimping, the rear extension will include an external metal profile on which will be arranged at least one groove.

The projectile according to the invention is preferably fixed in the following manner.

First of all, the case 2 is crimped onto the ring 7 not attached to the projectile. In order to limit the deformations of the ring during this operation, however, a threaded retaining rod (not shown) is made in the tapping of the ring 7 which is made of a metallic material which is more deformable than that of the ring 7.

For a stainless steel ring we will adopt for example a brass rod. The purpose is to ensure a maintenance of the ring which avoids the irreversible deformations likely to interfere with the subsequent fixation of the projectile. The choice of a more deformable material ensures the possibility of removing the rod after crimping (avoid blocking the rod in the ring).

The projectile is fixed in a second time to the ring by screwing its rear extension 6 on the ring 7 until abutment of the flange 6b on the ring 7.

Such a mode of implementation makes it possible to avoid crimping a projectile containing pyrotechnic compositions. This increases the security of operations.

An embodiment has thus been described in which the rear extension 6 is formed in one piece with the bottom 4 of the projectile 3.

It is understood that, according to the invention, we can define the extension 6 in the form of a separate part of the projectile.

The figure 4 shows such an embodiment in which the extension 6 is a one-piece metal part having a cylindrical cavity 11. This part 6 is fixed to the bottom 4 of the projectile by a means 14 constituting the breaking means. This means here consists of screws 14 having a calibrated tensile strength, for example screws made of plastic material. It will also be possible to use metal screws. The breaking means will then consist of the threads of the threads made in the bottom 4 of plastic.

The extension 6 carries a groove 8 arranged on its external cylindrical profile, the groove on which will be set the case 2.

Note that the cylindrical cavity 11 is delimited on the side of the body 4 of the projectile by an annular partition 16 on which the heads of the screws 14 and the cavity communicates by a bore 15 with the bottom 4 of the projectile.

Thus, during the firing, the pressure of the gases will be exerted on this bottom of the projectile which will cause a tensile stress at the various screws 14 which will break freeing the projectile (when implementing plastic screws ). If metal screws 14 fixed in the plastic base 4 are used, the pressure of the gases will cause a shear stress in the threads of the threads receiving these screws 14. These threads will break and the entire screws will remain attached to the metal extension 6 .

In all cases the metal extension 6 will however remain integral with the case 2.

Fixing the extension 6 will be done during the mounting stages of the projectile and then attaching to its case 2.

The essential point of the invention is that the extension comprises an external metallic profile (the extension itself or a ring attached thereto) having a sufficient mechanical strength to allow the crimping of the holster and that during the shooting this extension remains attached to the case.

Claims (10)

1. A process to attach a metallic casing (2) for a projectile (3) which has a body (4) at least partly made of a plastic material, process characterized in that the projectile (3) is given a rear extension (6) separated from the projectile body (4) by at least one fracturing means (9), the rear extension (6) having or incorporating a metallic external profile upon which at least one recess (8) is made, the casing (2) being attached by being crimped onto this recess (8).
2. Attachment process according to Claim 1, characterized in that the metallic external profile is formed by a ring (7) onto which the casing (2) is crimped, the projectile (3) being attached thereafter to the ring (7) by the screwing of its rear extension (6) onto the ring (7).
3. Attachment process according to Claim 2, characterized in that, before crimping the casing (2) onto the ring (7), a retaining rod is positioned in said ring that is made of a metallic material that is more easily deformed than the material constituting the ring.
4. A projectile incorporating a body (4) at least partly made of a plastic material and intended to be attached to a metallic casing (2), projectile characterized in that it incorporates a rear extension (6) separated from the body (4) of the projectile by at least one fracturing means (9, 14), the rear extension having or incorporating a cylindrical metallic external profile upon which there is at least one crimping recess (8) intended to accommodate the casing (2).
5. Projectile according to Claim 4, characterized in that the rear extension (6) forms a single piece with the projectile body (4) and is made of a plastic material, this extension being fitted with at least one metallic ring (7) incorporating the crimping recess or recesses (8).
6. Projectile according to Claim 5, characterized in that the fracturing means (9) comprise at least one zone of reduced thickness between the extension (6) and the projectile body (4), zone delimited by at least one circular groove (10).
7. Projectile according to Claim 6, characterized in that at least one metallic reinforcing means (12a, 12b) is arranged in the groove (10) and made integral with the extension (6).
8. Projectile according to Claim 7, characterized in that the metallic reinforcing means is constituted by at least two half-rings (12a, 12b).
9. Projectile according to one of Claims 5 to 8, characterized in that the metallic ring (7) is linked to the rear extension (6) by threading.
10. Projectile according to Claim 4, characterized in that the rear extension (6) is made of a metallic material and fastened to the projectile body (4) by screws (14), the cylindrical external profile of this extension being provided with the crimping recess or recesses (8).

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