EP0752571B1 - Short trajectory projectile - Google Patents

Abstract

The projectile (1) consists of a front section (4) designed to follow a ballistic trajectory, and a rear section (5) which is made to disintegrate on firing. The rear section is made at least partly from a plastic material, and both front and rear sections have outer surfaces shaped to fit the calibre of the firing weapon. The projectile's front and rear sections can both be made from the same plastic material and in one piece, sepd. by an annular groove. The plastic is one which allows disintegration by the centrifugal forces generated on firing, while the front section can be reinforced by a jacket of polyamide or brass. Alternatively, the front and rear sections of the projectile can be made from different plastic materials, the rear section being of a plastic which disintegrates on firing, e.g. by means of adding a metallic powder charge.

Description

The technical field of the invention is that of projectiles having a shortened trajectory and in particular that of exercise shots.

EP96617 discloses an exercise ball with reduced range comprising a one-piece body made in one plastic loaded with metallic particles. The range of the ball is reduced thanks to the choice of a material lightened.

Also known from patent EP169171 is a projectile reduced range exercise that includes an alloy body of lead carrying a pyrotechnic tracer at its rear whose combustion causes a fusion at a given time asymmetrical of the wall of the projectile causing its destabilization.

Patent W09316349 describes a projectile for a tunnel shot whose trajectory is not reduced but which is disintegrates on impact against the walls of the shooting tunnel.

Patent US3170405 proposes a projectile which disintegrates as soon as it leaves the barrel. It includes a plastic envelope which contains a powder metallic.

We also know a reduced trajectory projectile by patent FR1550946 which is the basis of the preamble of the claim 1.

This document describes a projectile which has a part forward intended to have a ballistic trajectory, which allows you to shoot at a target.

The mass of the front part is however much lower to that of a normal projectile. The result is a trajectory shortened ballistics which authorizes a safe shooting on areas of land with reduced dimensions.

This projectile also has a rear part which disintegrates when fired at the exit of the barrel.

The back has a shirt filled with a compressed metal powder.

The advantage of such an arrangement is that the mass full of the projectile (front part and rear part) can be close to that of a normal projectile.

This results in a sufficient recoil of the weapon when firing, which allows the rearming thereof and provides the shooter the sensations of a shot with war projectiles.

However, the projectile described by FR1550946 presents disadvantages.

Thus the disintegration of the rear part of the projectile at the exit of the barrel of the weapon disperses a powder very fine metal which causes wear and tear on the barrel and may injure the shooter.

It is therefore essential to use glasses protection when firing such projectiles.

The projectile described by FR1550946 is also difficult to manufacture.

• Elle doit être suffisamment résistante pour ne pas éclater à l'intérieur du tube, car un tel éclatement entraínerait une usure inacceptable de celui-ci. De plus il provoquerait une fuite de gaz vers l'avant du projectile, nuisant ainsi à ses performances;
• Elle doit aussi être suffisamment fragile pour éclater à la sortie de l'arme et libérer la partie avant. En effet, une solidité excessive entraínerait la solidarisation des parties avant et arrière sur une trajectoire balistique non raccourcie.

Indeed the rear part must satisfy two contradictory requirements:

• It must be strong enough not to burst inside the tube, because such a burst would cause unacceptable wear thereof. In addition, it would cause a gas leak towards the front of the projectile, thus adversely affecting its performance;
• It must also be sufficiently fragile to burst at the exit of the weapon and to release the front part. Indeed, excessive strength would cause the joining of the front and rear parts on a ballistic trajectory not shortened.

Finally the mechanical characteristics of the loading of metallic powder may change during storage. The powder can agglomerate and resist more bursting, thus modifying the separation conditions front and rear parts and the performance of the projectile from the point of view of shooting accuracy.

It is the aim of the present invention to propose a projectile with shortened trajectory which does not present any such disadvantages.

Thus the projectile according to the invention is of design simple and inexpensive to manufacture. It includes front and rear parts that separate reliably and reproducible at the exit of the barrel of the weapon without cause wear on the tube, or spread metal powder dangerous for the shooter.

The projectile proposed by the invention is easily adaptable to any caliber of weapon and it ensures in all case a precise and reproducible ballistic trajectory, thus allowing a shooting exercise in conditions close to shooting with war projectiles.

Thus, the subject of the invention is a projectile with shortened trajectory comprising a front part intended for have a ballistic trajectory and a rear part which disintegrates when fired, projectile characterized in that the rear part at least made of plastic and the front and rear parts each have a profile external to the caliber of the weapon, profile which is intended for take the scratches from the gun.

Because of the use of a plastic material to realize at least the rear part of the projectile, we are assured to have a maintenance of the mechanical characteristics which whatever the conditions for storing the projectile and we facilitates the manufacture thereof.

The realization of an external profile to the caliber of the weapon, as well on the front part which is intended to have a ballistic trajectory only on the rear part which disintegrates at the exit of the weapon, allows to increase the reliability of the projectile and the reproducibility of performance obtained (accuracy and range of fire).

Indeed, the rotational drive ensures a reproducible external ballistics for the front part (thanks to gyrostabilization) and it facilitates the separation between the front and rear parts, which reduces disturbance caused by the rear part on the front part.

According to a first embodiment, the front part and the rear part are made of the same material plastic and form a one-piece body, the front part being separated from the rear part by a breaking point annular.

According to another embodiment, the body of projectile is made of a fragile plastic liable to burst under the action of centrifugal forces developed during firing, the front part being surrounded by a jacket of sufficient thickness to prevent it from bursting.

Advantageously, the shirt can be produced in one plastic material such as Polyamide, it could also be made of brass.

According to another embodiment, the front part and the rear part of the projectile are made of materials different plastics, the plastic constituting the rear part being a fragile material susceptible burst under the action of the centrifugal forces developed when firing.

The rear part may be extended by a nipple which enters a housing in the front part and ensures the connection of these two parties.

Preferably used as plastic fragile a plastic charged with a powder metallic.

According to a variant, the rear part of the projectile carries at least one initiator of longitudinal rupture.

• la figure 1a représente en coupe longitudinale partielle un projectile suivant un premier mode de réalisation de l'invention,
• la figure 1b est une coupe de ce projectile suivant le plan AA dont la trace est repérée à la figure 1a,
• la figure 2 représente en coupe longitudinale partielle un projectile suivant un deuxième mode de réalisation de l'invention,
• la figure 3 est une vue en coupe d'un troisième mode de réalisation de l'invention,
• la figure 4 est une vue en coupe d'un quatrième mode de réalisation de l'invention.

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. 1a represents in partial longitudinal section a projectile according to a first embodiment of the invention,
• FIG. 1b is a section of this projectile along the plane AA, the trace of which is identified in FIG. 1a,
• FIG. 2 represents in partial longitudinal section a projectile according to a second embodiment of the invention,
• FIG. 3 is a sectional view of a third embodiment of the invention,
• Figure 4 is a sectional view of a fourth embodiment of the invention.

Referring to Figures 1a and 1b, a projectile 1 is shown attached by a crimp 3 to a front part of a shell 2. The projectile has a front part 4 and a rear part 5 which are separated from each other by a throat 6.

The maximum diameter (Φ1) of the front part 4 is substantially equal to that (Φ2) of the rear part 5, these two parts being of the caliber of the weapon. So the parties front 4 and rear 5 have an external profile such that both take the scratches from the gun barrel when shoot.

The groove 6 constitutes a beginning of rupture which separates the front part 4 of the rear part 5. It also receives the annular crimping 3 of the sleeve and ensures the attachment of the projectile to the socket.

The rear part 5 of the projectile 1 also includes fracture primers 7 which extend longitudinally from groove 6 to the rear of the projectile. These primers of breaks are made in the form of grooves regularly distributed angularly (see also the Figure 1b).

The body of the projectile 1 is preferably made in one plastic charged with metallic particles, for example example in plastic loaded with bronze or tungsten. Of materials that can be used to make the projectile are described for example by patents FR-A-2528564 and FR-A-2691156.

We could for example use a polyamide or a polyester resin loaded with 60% to 90% by mass of particles metallic. The percentage of metallic powder will be chosen depending on the desired mass for the projectile. We will in principle adopt a powder charge allowing give the projectile a density greater than 3.

We will give the projectile a volume such that its mass is substantially that of a war bullet. So the recoil obtained during the shooting is of the same order as for a real shooting and weapon mechanisms can use this recoil to ensure the various armaments desired.

The metallic particles can be chosen from the following materials: bronze, copper, lead, tungsten.

The diameter of the metal particles will be between 0.04 and 0.1mm.

Additives may be added to this material, for example example a solid lubricant like molybdenum disulphide, which reduces friction between the projectile and the barrel of the weapon when firing which reduces wear on the barrel.

We can also provide an anti-shock additive (such as acrylic resin such as styrene butadiene methacrylate) to improve the resistance of the ball to the constraints of shoot.

The operation of this projectile is as follows.

When firing the front 4 and rear 5 parts take both scratches on the barrel.

They are therefore both subjected to a force of centrifugal inertia. The breaking point 6 is placed so that the mass of the front part is different that of the rear part (and preferably less than that of the rear part). The result is a differential acceleration between the two parties which causes a torsional shear at the point of failure 6.

The axial acceleration of the projectile increases the stresses undergone by its reduced section at the level of the initiation of rupture 6 and also promotes the separation of two parts of the projectile.

Front and rear parts separate from each other at the exit of the barrel of the weapon (or even inside the tube).

The front part pursues a ballistic trajectory which is shortened compared to that of a complete projectile in because of its reduced mass.

The rear part 5 bursts at the exit of the barrel of the weapon thanks to the presence of the longitudinal breaking primers 7 which weaken it.

The pieces on the back fall a few meters from the weapon. No metallic dust comes damage the barrel of the weapon or injure the shooter.

The bursting of the rear part does not occur at the inside of the tube because the latter maintains diametrically the projectile.

The advantage of this first embodiment is that it allows the projectile to be produced by a single molding or injection (monobloc projectile).

It is also easy to set projectiles to different ballistic characteristics when playing on mass ratios between front part 4 and rear part 5 (therefore on the position of the breaking point 6).

Thus, the closer the breaking point 6 is to the front of the projectile, the more the mass of the front part 4 will be reduced, and the more its ballistic trajectory will be shortened.

Depending on the impact resistance chosen for the projectile material we can provide on the part back of the primers of ruptures 7 more or less deep and / or more or less numerous. The aim being to ensure the bursting of the rear part 5 at the outlet of the weapon barrel while the front part remains intact.

We could in the extreme use an uncharged material to make this projectile, provided you provide initiations of ruptures sufficiently deep on the part back to ensure the bursting of this one. We will prefer however a charged plastic material in order to obtain a sufficient projectile mass to ensure the retreat of tear.

Figure 2 shows a second embodiment of the projectile 1 according to the invention.

In this embodiment, the front part 4 includes a core 8 made of fragile plastic (plastic loaded with metallic powder) which is covered with a shirt 9 made of resistant material.

We could for example make the brass shirt or still in an uncharged plastic, such as polyamide.

The core 8 forms a single piece with the part rear 5 of the projectile and thus constitutes a body of projectile whose front part is covered by the shirt.

The external diameters Φ1 and Φ2 of the front parts and back again are chosen so as to take both the scratches on the weapon.

The front and rear parts are separated by a groove 6 which constitutes a beginning of rupture and also allows the fixing the projectile on the sleeve 2 by crimping the latter.

The operation of this projectile is the same as that previously described.

The front and rear parts separate at the exit of the barrel of the weapon due to the rupture which occurs at throat level 6.

This particular embodiment makes it possible to work to make the projectile a very plastic fragile, for example comprising a metallic filler significant (greater than 85%), while ensuring mechanics of the front part (thanks to the shirt).

It then becomes possible to make projectiles whose mass is very close to that of the projectile of war with an axial congestion of the same order.

If the loaded material which constitutes the rear part 5 and core 8 is very fragile, it is no longer necessary to arrange primers for longitudinal breaks on the rear part 5, and it is even possible not to provide throat 6.

Indeed the rear part then bursts at the exit of the tube under the simple action of angular acceleration.

We can nevertheless carry out such primers of breaks if the chosen material has resistance to avoid any harmful disturbance to the front part during separation.

From the manufacturing point of view, the complete projectile by a single injection operation at the using a suitable bi-injection mold of known type.

Figure 3 shows a projectile 1 following a third embodiment in which the front part 4 and the rear part 5 are each made of a material different plastic.

The rear part 5 is made of a plastic material fragile (plastic loaded with metal) and it is defined by so as to be able to burst at the exit of the barrel of the weapon by the effect of centrifugal forces.

The front part 4 is made of a plastic material more resistant, for example an unfilled polyamide, or less loaded as the rear part.

The rear part 5 carries a frustoconical stud 10 which is placed in a corresponding housing 11 of the front part 4. This ensures the coaxiality of the parts front and rear.

The projectile can be produced in a single bi-injection mold. We can also make the front parts and back independently and then fix them by collage.

Depending on the mechanical characteristics of the material from the rear part 5, it is possible to provide longitudinal fracture initiators thereon and / or a groove separating the front and rear parts.

The scratch in the weapon as well by the party before the rear part (diameters Φ1 and Φ2) ensures there still the reproducibility of the separation conditions of two parts and the precision of the ballistic trajectory of the front part.

In the absence of groove 6, the attachment to a socket can be done by gluing.

FIG. 4 represents another embodiment, derived from that of figure 3, and in which the part front 4 of projectile 1 has a core 12 covered with a shirt 9.

The rear part is made of plastic fragile and it is linked to the front part by cooperation of the stud 10 with the frustoconical housing 11.

This embodiment allows part front of upper mass by combining a core 12 in material heavy plastic (but very fragile) with a shirt ensuring the mechanical strength of the front part.

We will preferably make the shirt in a material unloaded plastic, but we could also do the brass shirt.

It is of course possible to combine the different previous variants between them, and to propose in particular a projectile according to FIGS. 3 or 4 and comprising longitudinal breaks and / or a groove between front and rear parts.

Claims (9)

1. A projectile (1) having a shortened trajectory and incorporating a front part (4) intended to have a ballistic trajectory and a rear part (5) that disintegrates during firing, such projectile being characterised in that the rear part (5) at least is made of a plastic material and that the front (4) and rear (5) parts each have an external profile calibred to the weapon, such profile being intended to mesh with the rifling of the barrel.
2. A projectile according to Claim 1, characterised in that the front part (4) and the rear part (5) are made of the same plastic material and form a single body, the front part (4) being separated from the rear part (5) by a ringshaped incipient fracture (6).
3. A projectile according to Claim 2, characterised in that the body is made of a fragile plastic material likely to burst under the action of the centrifugal forces developed during firing, the front part (4) being enclosed in a sleeve (9) that is thick enough to prevent it from bursting.
4. A projectile according to Claim 3, characterised in that the sleeve (9) is made of a plastic material such as a polyamide.
5. A projectile according to Claim 3, characterised in that the sleeve (9) is made of brass.
6. A projectile according to Claim 1, characterised in that the front part (4) and the rear part (5) are made of different plastic materials, the plastic material constituting the rear part being a fragile material likely to burst under the action of the centrifugal forces developed during firing.
7. A projectile according to Claim 6, characterised in that the rear part (5) is extended by a stub (10) that penetrates inside a housing (11) in the front part (4) and joins these two parts together.
8. A projectile according to one of Claims 3 to 7, characterised in that the fragile plastic material is a plastic material reinforced with metallic powder.
9. A projectile according to one of Claims 1 to 8, characterised in that the rear part (5) carries at least one longitudinal incipient fracture (7).

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