EP0307307B1 - Connection ring between a missile and a cartridge case - Google Patents

Abstract

The technical sector of the invention is that of connecting devices between a projectile and a case. The device according to the invention comprises a ring (6) which has a front part (8) connected to the projectile by a first fastening means and a rear part (7) fixed to the case (2) by a second fastening means. The device is characterised in that the second fastening means is shaped in such a way that the action of the pressure of the combustion gases of the propellant charge exerted on the projectile (1) causes the separation of the latter, carrying the ring, and of the case, and in that the rear part (7) then comes into contact with an inner surface of the chamber (4) so as to ensure gastightness. The invention is used for ammunition of the backswept type fired from a smooth barrel. <IMAGE>

Description

The field of the present invention is that of connecting devices between a shell, containing a propellant charge, and a projectile and more particularly between a combustible shell and a projectile of arrow type fired in a smooth tube.

The most commonly adopted solution for securing a metal case and a projectile is to practice an annular crimping of the case on the projectile. This crimping is actually possible, despite the difference in diameter between these two elements, due to the ease of producing metal sockets having a conical front part which adapts to the outside diameter of the projectile.

The use of combustible sockets, which has become more and more frequent due to the high firing rates that they allow, prohibits such a mode of connection due to the mechanical fragility of this type of socket and the difficulty in obtaining sockets fuels with a conical front part.

Various solutions were then proposed to secure the combustible case and the projectile. US Pat. No. 4,487,131 describes a ring, glued to the combustible sleeve, and having elastic tongues intended to pinch an arrow projectile shoe at its rear part. The elasticity of the tongues thus ensures good mechanical strength of the assembly.

An arrow projectile consists of a penetrator made of heavy material (for example Tungsten), under calibrated, surrounded by a fragmentable hoof comprising several elements (generally three), the mounting of such a projectile requires the hoof elements to be joined together around the indenter, the latter is obtained in part by mounting the sealing belt on the shoe.

It was tempting to try to combine the gas tightness function resulting from the combustion of the propellant charge and the projectile-shell connection function in a single connection ring.

Patent US4444113 describes a high pressure seal for a fragmentable sabot projectile. This seal is constituted by a skirt which locks by elastic deformation, on the one hand on the rear part of the shoe, and on the other hand on the mouth of a socket. An annular rupture initiator allows the separation of the sleeve and the projectile under the effect of the pressure of the propellant gases. This pressure, exerted on the internal surface of the skirt, will cause a translation of the latter on ramps integral with the hoof, which will bring it into contact with the internal surface of the barrel of the weapon where it will provide an effective seal at high pressures (of the order of several hundred MPa) prevailing in the tube. The main defect of such a device is its lack of efficiency for low pressures (of the order of a few MPa), but this low pressure seal is essential in the first tenths of milliseconds after ignition of the propellant charge, and this especially in the case of the use of a combustible case, in fact the confinement ensured by such a case is less than that obtained with a metal case and the displacement of the projectile then occurs for a lower pressure. A gasket insufficiently sensitive to be operational as soon as it ignites risks letting gases pass towards the front of the projectile, such a leakage being able to deteriorate the external surface of the gasket and cause a pressure drop reducing the efficiency of the propellant charge. Thus, this patent proposes to add, in front of the high pressure sealing skirt, a guide belt and a rubber ring pinched between skirt and belt, this arrangement making it possible to obtain the desired low pressure sealing. . Such an assembly is relatively complex to carry out, moreover the ramps which must be disposed on the shoe and which must also be covered with rubber in order to avoid any gas leaks between shoe and skirt, require machining and assembly operations. complementary.

It is the object of the invention to propose a single connecting device between a socket and a projectile which also ensures sealing at a low pressure level.

It is another object of the invention to provide a connection device which also ensures high pressure sealing, thus avoiding the addition of additional systems. In addition, the device according to the invention makes it possible on the one hand to simplify the mounting of an arrow projectile and on the other hand to facilitate the attachment of the latter with a combustible case, while ensuring good resistance of the ammunition to shocks.

Thus the invention provides a connecting device between a cartridge case containing a propellant charge and a projectile intended to be fired by a weapon comprising a chamber communicating with a tube, device constituted by a ring comprising a front part, made integral with the projectile by a first fixing means, and a rear part made integral with the socket by a second fixing means, which is shaped so that the action of the pressure of the gases of combustion of the propellant charge acting on the projectile, causes the separation of the latter carrying the ring and the socket, characterized in that the socket being combustible, the rear part comes during its separation from the latter in contact with an internal surface of the chamber, so as to produce gas tightness, and in that the front and rear parts are separated by at least one rupture initiator, the latter being shaped so as to be break, thus causing the separation of the front and rear parts, this separation occurring after that of the casing and the projectile, and consecutively in contact with the latter with the barrel of the weapon, the front part then being applied to the inner surface of the tube, under the action of gas pressure.

The rear part may include at least two weakening zones arranged along generators, and the front part at least one circular groove on its external surface.

The first fixing means may consist of a concordance of shapes between the front part of the ring and the lateral surface of the projectile, and in particular the front part may come to be housed in an annular groove made on the lateral surface of the projectile or else be screwed on the latter.

According to a preferred embodiment, the second fixing means is constituted by a cylindrical surface, arranged on the rear part of the ring, on which is adjusted and riveted and / or glued the sleeve.

According to an embodiment, the second fastening means comprises a cylindrical intermediate piece which can be glued to the interior surface of the sleeve.

• la figure 1 est une représentation partielle en coupe d'une munition mise à poste dans la chambre d'une arme et équipée du dispositif de liaison selon l'invention.
• la figure 2 est une vue de la bague de liaison suivant la direction A de la figure 1.
• la figure 3 est une représentation partielle du projectile dans le tube de l'arme après séparation des parties avant et arrière de la bague de liaison.
• la figure 4 est une représentation d'un deuxième 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 in which:

• Figure 1 is a partial sectional representation of an ammunition stationed in the chamber of a weapon and equipped with the connecting device according to the invention.
• FIG. 2 is a view of the connection ring in the direction A of FIG. 1.
• Figure 3 is a partial representation of the projectile in the barrel of the weapon after separation of the front and rear parts of the connecting ring.
• Figure 4 is a representation of a second embodiment of the invention.

Referring to FIG. 1, a projectile 1 summarily represented, (here a shoe carrying a sub-projectile of arrow type), is made integral with a combustible case 2 by means of a connecting ring 6. The assembly sleeve-ring-projectile is shown here stationed in a chamber 4 of a weapon, the projectile 1 is is then partially engaged in the tube 3 of the weapon, the front part of the chamber has a connection cone 5, and the tube is a smooth tube.

The connecting ring 6 has a front part 8 which is made integral with the projectile by a first fastening means, which here is a shape agreement between the front part of the ring and an annular groove 10 arranged on the lateral surface of the projectile 1 The outer diameter of the ring 6 at this front part 8 is slightly greater than the diameter of the tube 3 (the difference in diameter is of the order of 1% of the caliber), and the outer cylindrical surface of this ring carries circular grooves 14 whose function will be explained later.

The ring also has a rear part 7 which is secured to the sleeve 2 by a second fixing means, which here comprises an intermediate cylindrical part 12, glued to the internal cylindrical surface of the sleeve, this part may be made of loaded cellulose or not of cotton-powder, such a material being particularly easy to stick on a combustible socket. The intermediate piece is fixed to the rear part 7 of the ring 6 by means of rivets 13 regularly distributed over a circular generator of the ring. At the intermediate piece 12, the outside diameter of the rear part of the ring 6 is thus substantially equal to the outside diameter of the bushing, and the connecting ring therefore has a conical portion 15 ensuring the connection of this rear part with the front section 8.

Front part and rear part are also separated by a breaking point 9 which is here a circular groove produced on the inner surface of the ring in front of the conical portion 15.

The rear part comprises, both at its conical portion and its cylindrical portion, weakening zones 11, arranged along generators and regularly spaced from each other. Figure 2 allows to better see the distribution of the weakening zones 11, here four zones obtained by reductions in the thickness of the ring.

When the casing carrying the ammunition is placed, the projectile is only partially engaged in the barrel of the weapon and is therefore not in contact with the latter. The front part of the ring 6, the outside diameter of which is slightly greater than the diameter of the tube, is located opposite the connection cone 5. The ignition of the propellant charge contained in the socket 2 will generate gases, the pressure then acting both on the sleeve, the ring and the projectile will cause tensile stresses both at the level of the ring and of the fixing means, of the initiation of rupture and of the sleeve. The dimensioning of the ring and the fixing means will be such that the rupture of the second fixing means will occur before that of the initiation of rupture 9. It will suffice for this to play on the thickness of the intermediate piece and on the depth of the circular groove constituting the initiation of rupture 9.

The separation of the sleeve and the projectile carrying the ring allows the latter, pushed by the gases, to advance into the tube. The pressure of the gases, by acting on the inner surface of the ring, will bring the rear part 7 into contact with an inner surface of the chamber at the level of the connection cone 5, and this in the first tenths of milliseconds following the separation (this delay can possibly be adjusted by varying the thickness of the ring, the distance between first and second fixing means, the number and distribution of the weakening zones 11), thus the rear part 7 of the ring allows '' obtain a seal at low pressure gases (a few MPa), seal achieved almost instantaneously, which makes it possible to use the propellant charge optimally.

When the front part 8 of the ring enters the tube and comes into contact with it, thus realizing the centering of the projectile, the resistance opposed by the tube to passage of the rear part will create tensile stresses in the ring which will cause the separation of the front and rear parts at the level of the initiation of rupture 9. At this time the pressure prevailing in the chamber is sufficiently high, (of on the order of a few tens of MPa), so that the contact between the front part and the internal surface of the smooth tube is sufficient to ensure the seal between the latter and the projectile. Figure 3 shows the projectile, carrying the front part of the ring, in the barrel of the weapon. It is also possible to adjust the efficiency of the high pressure seal thus obtained by varying the thickness of the front part 8, and the distance between the first fixing means and the initiation of rupture, in addition the circular grooves 14 practiced on the outer cylindrical surface, playing the role of baffles, provide a complementary sealing function (any possible start of leakage of gases towards the front of the projectile is stopped, these decompressing in the baffle).

The rear part of the ring as well as the intermediate piece 12 and the rivets 13 are expelled from the barrel of the weapon with the combustion gases following the projectile. The weakening zones 11 allow a dislocation of the rear part, as a result of the passage of the connection cone, thus facilitating its ejection from the tube, a reduction in the size of the ejected pieces being also appreciable so as to avoid deterioration of the tail of the arrow sub-projectile.

It is thus seen that the device according to the invention has made it possible, on the one hand to obtain a low pressure seal thanks to the rear part of the ring, and on the other hand to ensure high pressure seal in the smooth tube of the weapon through the front part of the ring.

Another advantage of the invention is due to the simplification of the manufacturing. The ring will thus preferably be made of a thermoplastic polymer which will be injected around the projectile. In this way we will obtain the joining of the different elements constituting the shoe with the sub-projectile, (in the case of an arrow projectile). The intermediate piece will then be riveted to the ring, then the assembly thus obtained secured to the socket by gluing. The choice of an intermediate piece of cellulose, or of cardboard loaded or not with cotton-powder, makes it possible on the one hand to facilitate the fixing by gluing on a combustible bushing, and on the other hand to ensure a certain flexibility in this connection, flexibility essential to avoid ruptures of the fuel socket at this level.

FIG. 4 shows another embodiment of the invention in which only the second fixing means used differs from the previous one.

Here the ring 6 comprises, arranged on the rear part 7, a cylindrical surface 16 which thus delimits an area of reduced thickness, therefore more fragile, which plays a role similar to that of the cylindrical intermediate piece 12 of the previous example. The sleeve fits on the ring at the level of the bearing and is made integral with it by rivets (or else glue). Rivets and / or glue and cylindrical seat 16 thus constitute the second means of fixing the rear part 7 of the ring 6 with the sleeve.

The operation is the same as that described above, the tensile stresses supported by the bushing-fixing-ring assembly will cause the bushing and the ring to separate, the separation occurring either by breaking the cylindrical seat 16 ( the fragility of the latter being adjustable by varying its thickness and the number of rivets), or by rupture of the combustible sleeve at the level.

After separation, the rear part 7 of the ring acts as a low pressure seal already described. The flexibility of the shell-projectile connection, making it possible to avoid ruptures of the combustible shell, is here provided by the ring itself.

The manufacturing method is the same as that previously described: the ring in thermoplastic polymer will be injected around the projectile and will bring together the various elements constituting the shoe.

• la pression des gaz provoque dabord la rupture du deuxième moyen de fixation et ainsi la séparation de la douille et du projectile portant les deux parties de la bague;
• puis que la séparation des parties avant et arrière intervienne comme suite au contact entre le projectile et le tube de l'arme, en particulier en raison de la resistance opposée par ce dernier au passage de la partie arrière.

Other variants are possible without departing from the scope of the invention. It is possible to envisage other fixing means: other types of shape concordance between the front part of the ring and the lateral surface of the projectile, for example a connection by threading or even by rivets. The intermediate piece can be integrated into the ring by being arranged in the injection mold of the latter, or else bonded to the ring. The front and rear parts may constitute two separate parts, secured to the assembly, either by means of rivets pinching these two parts simultaneously, or by a second cylindrical intermediate part glued on both the front and rear parts. The breaking point 9 will then be formed by these rivets or else by this intermediate piece, the main thing being that the dimensioning of the fixing means is such that:

• the pressure of the gases first causes the rupture of the second fastening means and thus the separation of the sleeve and the projectile carrying the two parts of the ring;
• then that the separation of the front and rear parts occurs as a result of contact between the projectile and the barrel of the weapon, in particular because of the resistance opposed by the latter to the passage of the rear part.

It is possible to apply the invention to any type of projectile. In the case of projectiles intended to be fired in a smooth tube (arrow or hollow charge projectiles), a rupture initiation will be provided between the front part and the rear part of the ring, and the front part of the ring will then play the role of high pressure seal described above.

For projectiles fired in striped tubes, the invention will allow the use of combustible cartridges, this despite the fact that with such cartridges the movement of the projectile occurs for a lower pressure in the chamber of the weapon which could cause gas leaks towards the front of the projectile before taking scratches. The rear part of the ring of the device according to the invention will ensure a low pressure seal before scratching by the projectile belt.

In such a configuration, the front part of the ring may or may not be integral with the belt, and the initiation of rupture between the front part and the rear part may be omitted, the high pressure sealing function being fulfilled by the belt itself. For arrow projectiles intended to be fired in striped tubes and therefore carrying a slip belt, the front part of the ring will preferably be secured to the belt.

Claims (9)

1. Device for connecting a cartridge case (2) containing a propellant charge to a projectile (1) designed to be fired from a weapon having a chamber (4) communicating with a barrel (3), consisting of a ring (6) having a front portion (8), fastened to the projectile by a first means of attachment, and a rear portion (7) fastened to the cartridge case by a second means of attachment designed in such a way that the pressure of the combustion gases of the propellant charge exerted on the projectile (1) causes the separation of the said projectile carrying the ring (6) from the cartridge case, characterised by the fact that, the cartridge case being combustible, the rear portion (7) during its separation from the said cartridge case comes into contact with an inner surface of the chamber (4) so as to form a gas seal, and that the front and rear portions (8) and (7) are separated by at least one fracture zone, the latter being designed to fail causing the separation of the said portions after the separation of the cartridge case and the projectile (1) and following contact of the latter with the gun barrel, the front portion (8) then being pressed against the inner surface of the barrel by the action of the gas pressure.
2. Connecting device according to claim 1, characterised by the fact that the rear portion (7) has at least two weakened zones (11) arranged along generators.
3. Connecting device according to claim 1 or 2, characterised by the fact that the ring (6) has at least one circular groove (14) on the outer surface of its front portion (8).
4. Connecting device according to claims 1 to 3, characterised by the fact that the first means of attachment consists in matching the front portion (8) of the ring (6) to the lateral surface of the projectile (1).
5. Connecting device according to claim 4, characterised by the fact that the front portion (8) fits into an annular groove (10) made on the lateral surface of the projectile (1).
6. Connecting device according to claim 4, characterised by the fact that the front portion (8) is screwed on the projectile (1).
7. Connecting device according to claim 1 or 2, characterised by the fact that the second means of attachment consists of a cylindrical surface (16) made on the rear portion (7) of the ring (6), on which the cartridge case (2) is fitted and rivetted and/or glued.
8. Connecting device according to claims 1 to 6, characterised by the fact the second means of attachment comprises a cylindrical intermediate part (12).
9. Connecting device according to claim 8, characterised by the fact that the intermediate part (12) in glued on the inner surface of the cartridge case (2).

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