Abstract:
An ammunition comprising a projectile attached to a combustible skirt and enclosed by a base, a linking dome being provided between the skirt and the base, wherein the linking dome includes a first outer wall contacting with the skirt and a second outer wall extending from the first one and contacting with the base, and wherein the dome comprises a unit to ensure its joining with the skirt, the unit being able to be bent back by the base onto an outer wall of the combustible skirt when the base is disposed over the linking dome.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of Invention 
     The technical scope of the present invention is that of large caliber ammunition for tank cannons and which incorporate a combustible casing or skirt that is loaded with explosive powder via the rear of the casing. 
     2. Description of Related Art 
     Ammunition comprising a combustible skirt is well known. The combustible skirt or casing carries a projectile at its front part and its closed at its other end by a metallic base. 
     Thus, patent FR-A-2799831 discloses ammunition of this type in which the combustible skirt is attached to a dome by rivets, the dome being capped by the base. Attachment means are provided between the dome and base. One major disadvantage of this ammunition lies in the organizational complexity of the assembly which requires numerous handling operations. Another disadvantage lies in the risk of the connecting rivets between the skirt and the dome becoming detached. 
     SUMMARY OF THE INVENTION 
     The aim of the present invention is to supply ammunition that can be loaded from the rear and which incorporates means enabling the base to be attached simply but which provide great resistance when this ammunition is subjected to traction or torsion stresses. 
     The invention thus relates to large caliber ammunition constituted by a projectile attached to a combustible skirt and closed by a base, a linking dome being provided between the skirt and the base, wherein the linking dome incorporates a first lateral wall cooperating with the skirt and a second lateral wall extending the first one and cooperating with the base, and wherein said dome comprises means to ensure its joining with the skirt, such means being able to be bent back by the base onto the lateral wall of the combustible skirt. 
     According to one characteristic of the invention, the linking means are fastened at the junction between the first and second lateral walls. 
     Advantageously, the linking means are constituted by flexible tabs. 
     According to another characteristic of the invention, the flexible tabs are provided with ridges enabling the dome to be immobilized on the skirt. 
     Advantageously, the tabs are part of the dome. 
     According to a variant embodiment, the tabs are attached to the dome by attachment means. 
     According to another characteristic of the invention, the dome incorporates a central ring integral with the lateral walls by arms, said ring having a drill hole to accommodate an igniter. 
     According to another characteristic of the invention, the arms are in the shape of convex-curved arcs fitted with means to centre the base. 
     According to another characteristic of the invention, the centering means are constituted by bosses intended to cooperate with matching notches in the base. 
     According to another characteristic of the invention, the igniter is held in the drill hole on one side by a system of snugs/notches and on the other by an elastic ring. 
     Advantageously, the igniter is linked to the base by a nut. 
     A first advantage of the ammunition according to the invention lies in the simplification of its manufacture, which only requires simple handling operations that do not require specific qualifications. 
     Another advantage lies in the resistance obtained for the skirt/dome/base link. 
     Another advantage lies in the fact that the assembly requires no mounting rivets. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other characteristics, particulars and advantages of the invention will become more apparent from the following description given by way of illustration and with reference to the drawings, in which: 
         FIG. 1  shows a section of the rear end of a piece of ammunition, 
         FIG. 2  shows the two phases to mount the igniter on the dome, 
         FIG. 3  shows a view illustrating the positioning of the dome with respect to the base, 
         FIGS. 4 and 5  are sections of the rear part of a piece of ammunition showing the intermediate and final positioning of the ammunition elements, 
         FIGS. 6 and 7  are views to illustrate the dome being set into position on the combustible skirt, and 
         FIG. 8  is a view showing the positioning of the base on the dome. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     As emerges from the above, large caliber ammunition for tank cannon comprises a projectile (not shown in the Figures), integral with a combustible skirt enclosing a propellant charge. A base closes the combustible skirt at its rear part and enables it to be fired from a gun. This type of ammunition is intended to be fired from a tank cannon. To introduce the load into the combustible skirt, different devices have been imagined, and the invention relates to the use of an intermediate dome between the skirt and the metallic base of the ammunition. 
     The remainder of the description will focus on the joining of the combustible skirt, the dome and the base, the other elements and manufacturing processes of the ammunition being well known to some skilled in the art. 
     This is why  FIG. 1  features a section of the rear part of a piece of ammunition  1  incorporating a combustible skirt  2 , a dome  3  and a base  4 . The skirt  2  is combustible and classically formed of cardboard impregnated with nitrocellulose. The dome  3  is a part made of a plastic material and the base  4  is a solid metallic part. 
     The skirt  2  is provided with two successive narrowed sections  5  and  6  whose function will be explained hereafter. The dome  3  is fitted with an igniter  7  held by an elastic ring  8  which engages in a groove made in the dome. The dome comprises linking means  10  cooperating with the skirt and base. The base  4  is provided with a lip  9  (for example made of rubber) that is intended to ensure sealing during the ignition of the load after firing from the cannon. 
       FIG. 2  shows an exploded view of the dome  3  and an assembled view. The dome  3  incorporates a first lateral wall intended to cooperate with the skirt  2  and a second lateral wall  12  extending the first one and intended to cooperate with the base  4 . The lateral wall  12  has an external diameter that is slightly greater than that of the wall  11  so as to form a limit stop for the skirt  2 . The dome comprises linking means  10  and, in the Figure these can be seen to be attached at the junction of the first  11  and second  12  lateral walls. 
     The linking means  10  are either integrated into the dome when this is being manufactured, or are attached to it by any means, such as for example, bonding. These are in the form of flexible tabs  10   a  and  10   b . In an advantageous embodiment, four pairs of tabs can be provided evenly spaced around the external wall of the dome. 
     The dome  3  incorporates a central ring  13  integral with the lateral wall  11 ,  12  by arms  14 . The ring  13  has a drill hole  15  to accommodate the igniter  7 . The arms  14  are in the form of convex curved arcs each provided with means to centre the base  4 . These centering means are constituted by bosses  18  intended to cooperate with matching notches  19  made in the base  4  (and can be seen in  FIG. 3 ). The free space  16  between each arm  14  enables the powder forming the load to be introduced. Once again, the igniter  7  can be seen to be provided with notches  17  intended to cooperate with the dome  3  during its attachment. 
     The exploded view shows the initial position of the igniter  7  of the dome  3  and the elastic ring  8 . The assembled view  7  shows the attachment of the igniter  7  in the drill hole  15  in the dome being attached by the elastic ring  8  pressing on a shoulder of the drill hole  15 . Thus, the igniter  7  is rigidly attached to the dome  3 . The igniter  7  can be seen after attachment to have a threaded part which protrudes with respect to the dome. 
       FIG. 3  shows the dome  3  directly above the base  4 . This view firstly enables part of the linking means of the dome  3  and base  4  and secondly part of the linking means with the igniter to be seen. The base  4  is provided with notches  19  in which the bosses  18  (visible in  FIG. 2 ) are engaged. The introduction of these bosses in the notches  19  enables the base  4  and dome  3  to be made integral in rotation.  FIG. 3  further shows that the dome  3  is provided with snugs  20  level with the central ring  13  that engage the notches  17  in the igniter  7  thereby ensuring an immobilization in rotation of this igniter with respect to the dome  3 . 
       FIG. 3  shows that the tabs  10  are provided with ridges  21  intended to hook onto the skirt  2  during assembly. 
       FIG. 4  shows a section illustrating an intermediate phase in the assembly of the three elements. The dome  3 , assembled with the igniter as shown in  FIG. 2 , is introduced into the skirt  2 . The skirt  2  is positioned at wall  11  and thus buts against the edge of wall  12 . The base  4  caps the dome  3  causing the tabs  10   a ,  10   b  to be pressed against the narrowed part  6  of the skirt. The ridges  21  on the tabs ensure that the dome  3  is held on the skirt  2 . Once they have been pressed down, the tabs  10  are arranged so as not to cause extra thickness with respect to the profile of the narrowed part  5  of the skirt. 
       FIG. 5  shows the final position of the three elements where the base  4  can be seen to be pressing closely on the dome  3 . The base  4  can be seen to be joined to the dome  3  by means of the igniter  7  and the net  22  also ensures that the skirt  2  is pinched between the dome  3  and the tabs  10 . The dome  3  is thus joined to the skirt  4 , effectively making the skirt, the dome and the base integral with one another. 
     As can be seen, this structure improves the skirt&#39;s loadability and simplifies the integration of the ammunition during the casing process. 
     For the manufacture of the ammunition, reference will be made to  FIGS. 6 to 8 . After having set the igniter  7  into position in the dome, as explained with reference to  FIG. 2 , the dome is placed above the skirt  2  as can be seen in  FIG. 6 . The dome  3  is inserted by sliding the wall  11  in the skirt until it buts against wall  12 , as can be seen in  FIG. 7 . The propellant charge powder may then be introduced via one of the free spaces  16  at the rear of the loading dome. At the end of this loading operation, the base  4  is set into position, as can be seen in  FIG. 8 , until it presses against the tabs  10 . Naturally, the grooves  19  are made to lie opposite the bosses  18 . A further pressure is applied to the base  4  so as to fold the ridged tabs  10 , thanks to the base, right back against the external surface of the skirt  2 . The base  4  is pushed in until the threaded part of the igniter  7  protrudes with respect to the base. The nut  22  (seen in  FIG. 5 ) is then tightened to lock the assembly on the skirt. 
     By tightening the nut, the link is made both between the base  4  and the dome  3  and between the skirt  2  and the dome  3 .