FR2620214A1 - CONNECTING RING BETWEEN A PROJECTILE AND A BUSHING - 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.

Description

The field of the present invention is that of the connecting devices

  between a bushing, containing a propellant charge, and a projectile and more particularly between a fuel bush and an arrow projectile fired in a smooth tube. The most commonly adopted solution to make a metal sleeve and a projectile integral is to practice an annular crimping of the socket on the projectile. This crimping is actually possible, despite 0 the difference in diameter between these two elements, because of the ease of production of metal sleeves having a conical front portion that fits the diameter

outside the projectile.

  The use of fuel sockets, which has become more and more frequent because of the high firing rates they allow, prohibits such a mode of connection because of the mechanical fragility of this type of socket and the difficulty in obtaining sockets. presenting fuels

a conical front part.

  Various solutions have then been proposed for joining the fuel bush and the projectile. US4487131 discloses a ring, glued on the fuel bushing, and having resilient tongues for gripping an arrow projectile shoe at its rear portion. The elasticity of the tongues thus ensures the

  good mechanical strength of the whole.

  An arrow projectile is constituted by an indenter in heavy material (for example Tungsten), under calibrated, surrounded by a fragmentable shoe comprising several elements (generally three), the mounting of such a projectile requires the attachment of the elements of the shoe around the indenter, the latter is achieved in part by

  mounting the sealing belt on the hoof.

  It was tempting to try to group together the gas-tight function resulting from the combustion of the propellant charge and the projectile-socket bonding function in

a single connecting ring.

  US 4444113 discloses a high pressure seal for a fragmentable shoe 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 primer allows the separation of the sleeve and the projectile under the effect of the pressure of the propellant gases. This pressure, acting on the inner surface of the skirt, will cause a translation thereof on integral ramps of the shoe, which will bring it into contact with the inner surface of the gun tube o it will ensure an effective seal at high pressures (from

  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 indispensable in the first tenths of milliseconds after ignition of the propellant charge, and this especially in the case of the use of a fuel bushing, in fact the confinement provided by such a bushing is less than that obtained with a metal bushing and the displacement of the projectile then intervenes for a lower pressure. An insufficiently sensitive seal to be operational from the moment of ignition may allow gases to pass to the front of the projectile, such a leakage may deteriorate the outer surface of the seal and cause a drop in pressure decreasing 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 to obtain the desired low pressure seal . Such an assembly is relatively complex to achieve, more ramps to be arranged on the shoe and must also be covered with rubber to prevent gas leakage between shoe and skirt, require machining

  and complementary editing operations.

  It is the object of the invention to provide a connection device between a socket and a projectile allowing

  to ensure a seal at low pressure level.

  It is another object of the invention to provide a connection device that also ensures a high pressure seal, 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 joining of the latter with a fuel bushing, while at the same time ensuring

  good resistance of the ammunition to shocks.

  Thus the invention proposes a connecting device between a bushing containing a propellant charge and a projectile intended to be fired by a weapon comprising a chamber communicating with a tube, a device constituted by a ring comprising a front part, made integral with the projectile by a first fixing means, and a rear portion secured to the socket by a second fixing means, the device is characterized in that the second fixing means is shaped in such a way that the action of the combustion gas pressure of the propellant charge exerted on the projectile, causes the separation of the latter carrying the ring and the sleeve, and in that the rear portion then comes into contact with an internal surface of the chamber, so as to achieve a

gas tightness.

  Preferably, the front and rear portions are separated by at least one rupture primer, the latter being shaped so as to break, thus causing the separation of the front and rear parts, this separation occurring after that of the socket 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 the gas pressure. The rear portion may comprise at least two weakening zones arranged along generatrices, and the front portion at least one circular groove on its outer 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 can be housed in an annular groove formed on the lateral surface of the projectile or be

screwed on the latter.

  According to a preferred embodiment, the second attachment means is constituted by a cylindrical seat, arranged on the rear part of the ring, on which is

  adjusted and riveted and / or glued the sleeve.

  According to another embodiment, the second fixing means comprises a cylindrical intermediate piece which

  can be glued to the inner surface of the socket.

  The invention will be better understood on reading the

  following description of particular modes of

  embodiment, description made with reference to the accompanying drawings

  in which: FIG. 1 is a partial sectional representation of a munition placed in the chamber of a weapon and

  equipped with the connecting device according to the invention.

  FIG. 2 is a view of the next connecting ring

the direction A of FIG.

  FIG. 3 is a partial representation of the projection

  tile in the weapon tube after separation of the parts

  front and back of the connecting ring.

  FIG. 4 is a representation of a second mode of

- realization of the invention.

  Referring to Figure 1, n projectile 1

  summarily represented, (here a hoof carrying a

  sub-projectile of the arrow type), is bound by a

  fuel socket 2 by means of a connecting ring 6.

  The sleeve-ring-projectile assembly is shown here placed in a chamber 4 of a weapon, the projectile 1 is then partially engaged in the tube 3 of the weapon, the front part of the chamber has a cone of

  connection 5, and the tube is a smooth tube.

  The connecting ring 6 comprises a front portion 8 which is secured to the projectile by a first fastening means, which here is a shape match between the front portion of the ring and an annular groove 10 provided on the lateral surface of the projectile 1 The outer diameter of the ring 6 at this front portion 8 is slightly greater than the diameter of the tube 3 (the difference in diameter is of the order of 1% of the size), and the outer cylindrical surface of this ring carries circular grooves 14 whose function will be specified later. The ring also comprises a rear portion 7 which is secured to the sleeve 2 by a second fixing means, which here comprises a cylindrical intermediate piece 12, bonded to the inner cylindrical surface of the sleeve, this part may be made of filled cellulose or non-cotton-powder, such material being

  particularly easy to stick on a fuel socket.

  The intermediate piece is fixed on the rear portion 7 of the ring 6 by means of rivets 13 regularly distributed over a circular generatrix of the ring. At the intermediate piece 12, the outside diameter of the rear portion of the ring 6 is thus substantially equal to the outside diameter of the sleeve, and the connecting ring therefore has a conical portion 15 ensuring the

  connection of this rear part with the front part 8.

  Front part and rear part are also separated by a breaking primer 9 which is here a circular groove made on the inner surface of the ring in front of the

conical portion 15.

  The rear portion comprises, both at its conical portion and its cylindrical portion, weakening zones 11, arranged along generatrices and regularly spaced from each other. FIG. 2 gives a better view of the distribution of the weakening zones 11, here four zones obtained by

  reductions in the thickness of the ring.

  When placing the bushing carrying the ammunition, the projectile is only partially engaged in the barrel of the weapon and is therefore not in contact with it. The front part of the ring 6, whose external diameter is slightly greater than the diameter of the tube, is opposite the connecting cone 5. The firing of the propellant charge contained in the sleeve 2 will generate gases, the pressure then acting on both the bushing, the ring and the projectile will cause tensile stresses at both the ring and the

  fastening means, the breaking primer and the socket.

  The dimensioning of the ring and fixing means will be such that the rupture of the second fastening means will take place before that of the rupture primer 9. It will be sufficient for this to play on the thickness of the intermediate piece and on the depth of the circular furrow

constituting the beginning of rupture 9.

  The separation of the sleeve and the projectile bearing the ring allows it, pushed by the gas, to advance in the tube. The pressure of the gases, acting on the inner surface of the ring, will put the rear portion 7 in contact with an inner surface of the chamber at the connecting cone 5, and in the first tenths of milliseconds following the separation (this time can possibly be adjusted by adjusting the thickness of the ring, the distance between the first and second fastening means, the number and distribution of the weakening zones 11), and the rear portion 7 of the ring allows 'get a seal at: - low pressure gas (a few MPa), seal achieved almost instantaneously, which allows to use the propulsive loading so

optimal.

  When the front portion 8 of the ring penetrates into the tube and comes into contact with it, thereby achieving the centering of the projectile, the resistance opposed by the tube to the passage of the rear part will create tensile stresses in the ring which will cause the separation of

  front and rear parts at the beginning of rupture 9.

  At this time the pressure in the chamber is sufficiently high (of the order of a few tens of MPa), so that the contact between the front portion and the inner 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 portion 8, and the distance between the first fastening means and the incipient fracture, in addition to the circular grooves 14 made on the outer cylindrical surface, acting as baffles, provide a complementary sealing function (any early leakage of gases to 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 tube of

  the weapon with the flue gas as a result of the projectile.

  The weakening zones 11 allow a dislocation of the rear part, as a result of the passage of the connecting cone, thus facilitating its ejection of the tube, a decrease in the size of the ejected pieces being also appreciable so as to avoid a deterioration of

  the empennage of the sub-projectile arrow.

  It can thus be 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 sealing in the smooth tube. of

  the weapon through the front part of the ring.

  Another advantage of the invention lies in the simplification of manufacture. 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 various elements constituting the hoof with the sub-projectile, (in the case of an arrow projectile). The intermediate piece will then be riveted on the ring, then the assembly thus obtained secured to the sleeve by gluing. The choice of an intermediate piece made of cellulose, or cardboard loaded or not cotton-powder, on the one hand to facilitate the fixing by gluing on a fuel sleeve, and on the other hand to provide some flexibility to this connection, essential flexibility to avoid breaks in the fuel bushing at this

level.

  FIG. 4 shows another embodiment of the invention in which alone differs with the preceding

  second fixing means used.

  Here the ring 6 comprises, arranged on the rear portion 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 part 12 of the previous example. The bushing fits on the ring at the level of the scope and is secured by rivets (or glue). Rivets and / or glue and cylindrical bearing 16 thus constitute the second means of fixing the rear portion 7 of the ring 6 with the sleeve. The operation is the same as that previously described, the tensile stresses supported by the bushing-fixing means-ring assembly will cause the separation of the sleeve and the ring, the separation intervening either by breaking the cylindrical bearing surface 16 ( the fragility of the latter being adjustable by varying its thickness and the number of rivets), or by

  rupture of the bush.combustible at the level of the range.

  After separation, the rear portion 7 of the ring plays the role of low pressure seal already described. The flexibility of the connection bush-projectile, to avoid the breaks of the bush fuel, is here ensured by the

ring itself.

  The method of manufacture is the same as that previously described: the ring of thermoplastic polymer will be injected around the projectile and will achieve the joining of the

  different elements constituting the hoof.

  Other variants are possible without departing from the scope of the invention. It is possible to envisage other means of attachment: other types of shape matching between the front part of the ring and the lateral surface of the projectile, for example a thread connection or by rivets. The intermediate piece may be integrated in the ring being disposed in the injection mold of the latter, or else glued on the ring. The front and rear parts may be two separate parts, secured to the assembly, either by rivets pinching simultaneously these two parts, or by a second cylindrical intermediate piece glued on both the front and rear parts. The rupture primer 9 will then be constituted by these rivets or by this intermediate part, the essential thing being that the dimensioning of the fixing means is such that: the pressure of the gases first causes the rupture of the second fixing means and thus the separation of the sleeve and the projectile carrying the two parts of the ring; since the separation of the front and rear parts takes place as a result of the 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 projectiles. In the case of projectiles intended to be drawn in a smooth tube (projectiles arrows or hollow charge), a beginning of rupture 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

previously described.

  For projectiles fired in striped tubes, the invention will allow the use of fuel bushings, despite the fact that with such sockets the displacement of the projectile intervenes for a lower pressure in the chamber of the weapon which could lead to gas leaks to the front of the projectile before making scratches. The rear part of the ring of the device according to the invention will ensure a low pressure seal before making scratches by the projectile belt. In such a configuration, the front portion of the ring may be secured to the belt or not, and the beginning of rupture between the front part and the rear part may be omitted, the high pressure sealing function being filled by the belt itself. For arrow projectiles intended to be drawn in striped tubes and thus carrying a slipping belt, the front part of the ring shall be

  preferably secured to the belt.

Claims (10)

  1. Device for connecting a sleeve (2) containing a propellant charge and a projectile (1) intended to be fired by a weapon comprising a chamber (4) communicating with a tube (3), a device constituted by a ring (6) comprising a front portion (8), secured to the projectile by a first fastening means, and a rear portion (7) secured to the socket by a second fastening means, characterized in that the second fastening means is formed of in such a way that the action of the pressure of the combustion gases of the propellant charge on the projectile (1) causes the separation of the latter carrying the ring (6) and the sleeve, and in that the rear part (7) then comes into contact with an inner surface of the chamber (4), so as to realize a gas tightness.   2. Connecting device according to claim 1, characterized in that the front (8) and rear (7) parts are separated by at least one breaking primer (9), the latter being shaped so as to break, thereby causing the separation of said parts, this separation occurring after that of the sleeve and the projectile (1), and consecutively in contact with the latter with the barrel of the weapon, the front part (8) then being applied to the surface inside the tube, under the action of the gas pressure.   3. Connecting device according to claims 1 or 2,   characterized in that the rear portion (7) comprises at least two weakening zones (11) arranged along generatrices.   4. Connecting device according to one of claims 1 to 3,   characterized in that the ring (6) has on the outer surface of its front portion (8) at least one groove circular (14).   Connecting device according to Claims 1 to 4,   characterized in that the first attachment means is a pattern match between the front portion (8) of the   ring (6) and the lateral surface of the projectile (1).   6. Connecting device according to claim 5, characterized in that the front portion (8) is housed in an annular groove (10) formed on the surface side of the projectile (1).   Connecting device according to Claim 5, characterized in that the front part (8) is screwed onto the projectile (1).   8. Connecting device according to one of claims 1 to 3,   characterized in that the second fastening means is constituted by a cylindrical seat (16), arranged on the rear part (7) of the ring (6), on which is adjusted   and riveted and / or glued the sleeve (2).   9. Connecting device according to claims 1 to 7,   characterized in that the second fixing means   has a cylindrical intermediate piece (12).   10. Connecting device according to claim 9, characterized in that the intermediate piece (12) is glued.   on the inner surface of the socket (2).