EP0646762B1 - Combustible case-elements for artillery projectiles, method of manufacture and use thereof - Google Patents

Description

The present invention relates to the field of artillery ammunition. More specifically the invention relates to fuel container components allowing to easily constitute loads modular fully combustible for such ammunition.

The invention also relates to a method obtaining such elements by a technique of felting.

For medium and large artillery ammunition we are looking more and more to have fully combustible propellant charges which allow to overcome constraints related to the use of non-combustible metal sockets. By elsewhere the propellant charge must be able to be modulated according to the parameters of the intended shot, a particularly interesting solution is that offered by modular loads.

Such loads are constituted by modules identical composed by a combustible case cylindrical with a central channel and filled with a loading of propellant powder. Depending of shooting parameters the weapon server determines the number of modules to use and possibly their nature.

If the solution of modular loads entirely fuel is very interesting theoretically, it is, in practice, of a limited implementation in because of the complexity presented so far by the practical realization of such modular loads.

A first realization was proposed by the Patent application FR-A-2 497 335. According to this request the fuel box includes a body and a bottom, a cover and a central tube. These different elements are made from combustible materials in plates by thermoforming and are glued together other. A first drawback presented by this solution lies in the correct positioning of different components of the housing and in particular in the correct positioning of the central tube intended for ensure the transmission of ignition from a box to the other. A second drawback lies in the implementation work of combustible materials to undergo a thermoforming operation.

In order to overcome this second drawback, the skilled person then sought to use fuel boxes obtained by a felting.

Another solution, described in the USP patent 4,922,823, thus consists in making the case by joining and gluing one against the other of two hollow cylindrical combustible elements each closed at one of their ends by a flat face having a central opening bordered by an interior high neck less than the height of said element. At time the assembly of the two elements must be put in place the central tube which is made up of powder propellant agglomerated and which rests on both central passes. A first drawback of such solution is the practical difficulty of achieving a such assembly. A second drawback is the difficulty to completely fill such a case with powder bulk propellant.

A solution similar to the previous one has been proposed by patent application EP-A-O 475 207.

This solution also consists in carrying out the fuel box from two elements cylindrical hollow fuel closed each to one of their ends by a flat face having a central hole assembled and glued one against the other. The central channel is a hollow tube of propellant powder agglomerated building on the inside of the two faces planes and the propellant charge is a block cylindrical hollow agglomerated propellant powder. This solution has the disadvantage of being limited to propellant charges in agglomerated powder and by elsewhere also has the disadvantage of correct positioning of the central tube.

The solutions known to date from the applicant therefore all have the major drawback of doing call to constitute the cylindrical case of a modular loading to building blocks that do not incorporate the central tube intended to ensure the ignition transmission. These solutions require so all of them have to put the central tube in place during assembly of the housing, installation which is delicate for mass production. otherwise the cases thus obtained are often difficult to completely load with loose powder. Finally he note that the more parts there are the more its cost price increases.

The object of the present invention is precisely to offer modular fuel containers whose housings do not have the aforementioned drawbacks.

The invention therefore relates to container elements fuel for artillery ammunition obtained by felting on a liquid permeable mold, aqueous suspension consisting mainly of nitrocellulose fibers, cellulose fibers and by a resin, so as to obtain a draft of the said element which is then compacted and hot cooked, according to the features of independent claim 1.

According to a first preferred variant of the invention the said plane part of revolution is bordered by a cylindrical outer wall located on the same side of the said flat part as said central pass.

According to a second preferred variant of the invention said outer wall has a height substantially equal to the height of said central neck.

1) on fabrique par feutrage, compactage et cuisson deux éléments complémentaires de conteneurs combustibles,

2) on remplit l'un des dits éléments avec une poudre propulsive,

3) on rend solidaire de l'élément ainsi rempli le second élément de manière à constituer un conteneur combustible rempli de poudre et possédant un canal central.

The invention also relates to the use of elements according to the invention in a process for producing combustible containers loaded with powder for artillery ammunition, characterized in that:

1) two complementary elements of combustible containers are manufactured by felting, compacting and baking,

2) one of the said elements is filled with a propellant powder,

3) the second element is made integral with the element thus filled so as to constitute a combustible container filled with powder and having a central channel.

Within the meaning of the present invention, we will say of two combustible container elements that they are complementary when, by joining together, they define a cylindrical case closed to each of its ends by a flat face having a central orifice, the two central orifices being connected continuously through a central channel consisting of the passes of said elements. As will be explained more far the two complementary elements are not, the more often, identical.

According to a preferred embodiment of the invention, introduced into the said central channel thus constituted a additional ignition tube. Preferably this ignition tube is obtained by agglomeration of grains propellant powder coated with a binder based on polyvinyl nitrate.

Finally, the invention also relates to a method of fabrication by felting of a blank of elements according to the invention characterized in that one immerses in a aqueous suspension consisting mainly of nitrocellulose fibers, cellulose fibers and by a resin, a mold having a cavity of revolution consisting of an outer shell and a bottom whose surface is flat and which has a column central, said bottom and said column at least being permeable to liquids and kept at a distance internal walls of the mold so as to form a empty space and in that one exerts an aspiration to inside said empty space.

According to a preferred variant of the invention, the said outer shell is, at least partially, permeable to liquids and delimits an empty space in which we can create a vacuum.

The invention thus makes it possible, from only two elements obtained by felting, to constitute a complete fuel module case for load artillery including the central channel, incorporates the said elements, does not require any particular positioning nor any gluing operation.

Furthermore, when one of the two elements constitutes the cover of the case and that the other element constitutes the body of the housing incorporating almost all of the central channel, the complete filling of the casing with propellant powder in grains is a very easy operation. Of course the box can also be filled with a load in the form of block or bundle.

The invention is now described in detail in referring to Figures 1 to 10.

Figure 1 shows, in partial view uprooted, a modular combustible container according to the invention.

Figures 2 and 3 show, seen in perspective, two complementary elements according to the invention, FIG. 2 representing a body of housing and Figure 3 a housing cover.

Figure 4 shows, in sectional view the configuration of the two complementary elements constituting a housing and shown in Figures 2 and 3.

Figure 5 shows, in section, another configuration of two additional elements according to the invention.

Figure 6 shows, seen in perspective, a mold for manufacturing by felting an element blank according to the invention.

Figure 7 shows, seen in section, the mold of the Figure 6 immersed in the felting suspension.

FIG. 8 represents, in perspective view, the central part of the mold shown in Figures 6 and 7.

Figure 9 shows, in perspective view, one of the two external shells of the mold shown in Figures 6 and 7.

Figure 10 is a magnifying glass of part L of the figure 7.

The invention relates to container elements fuel for artillery ammunition. We represented in Figures 2 and 4 such an element 1 according to the invention.

Typically such an element 1 has at least one flat part 2 of revolution having a central opening 3 bordered by a central neck hollow 4. According to a first preferred variant of the invention the said central orifice 3 is an orifice circular and the said hollow central neck 4 is a neck cylindrical. According to a second preferred variant of the invention said plane part 2 of revolution is bordered on its entire periphery by an outer wall cylindrical 5 located on the same side of said part plane 2 than the said central pass 4. Preferably, as shown in Figures 2 and 4, said wall exterior 5 has a height substantially equal to the height of said central neck 4. Such an element 1 is intended to constitute the body of a combustible container modular, the outer wall 5 constituting the wall outside of the container housing, the flat part 2 constituting the bottom of the case and the hollow neck4 constituting the ignition tube, the wall 5, the part plane 2 and the hollow neck 4 being in one piece.

FIGS. 3 and 4 show an element 6 complementary to the previous one.

This element 6 consists of a flat part 7 of revolution with a circular central opening 8 bordered by a hollow cylindrical neck 9. The flat part 7 of element 6 is bordered on its entire periphery by an outer cylindrical wall 10 located on the same side that the neck 9 and having a height substantially equal to that of the pass 9.

The outside diameter of the neck 9 of the element 6 is equal to the inside diameter of the neck 4 of the element 1 while the outside diameter of the outside wall 10 of element 6 is equal to the inside diameter of the outer wall 5 of the element 1. It is thus possible to penetrate the neck 9 of the element 6 in the neck 4 of element 1 so that the end 11 of the neck 4 comes into abutment against the inner surface of the flat part 7 of the element 6. Under these conditions the outer surface of the wall 10 of the element 6 is found in contact with the inner surface of the wall 5 of element 1.

Thus assembled, the housing body 1 and the element 6 which plays the role of cover define a housing cylindrical closed at each of its ends by a flat face with a central opening, both central openings being connected continuously by a continuous central channel formed by the neck 4 of element 1 in which the neck 9 of element 6 is fitted. It is in this sense that the two elements 1 and 6 are said to be complementary in the context of this invention.

Figures 2, 3 and 4 show a container fuel obtained from two elements complementary 1 and 6 in which the central neck and the outer wall have substantially the same height. Of such cases can be easily secured each other, for example by using a ring or an adhesive material.

The invention however also relates to combustible container elements in which the wall exterior has a height different from the height of the said central collar. There is shown in section in Figure 5 a combustible container case consisting of two additional elements 12 and 13.

Element 12 has a flat part 14 having a circular central orifice 15 bordered by a neck 16 of height much lower than that of the wall outside 17 which borders the flat part 14.

Element 13 on the contrary has a flat part 18 with a circular central opening 19 bordered by a neck 20 of height much greater than that of the wall exterior 21 which borders said flat part 18.

The inside diameter of the neck 20 is equal to outside diameter of the neck 16 while the diameter outside of wall 21 is equal to inside diameter of the wall 17 so that the element 13 can fit into element 12 as shown in figure 5.

It will be observed that on the embodiment represented at Figure 5 the height of the outer wall 17 of element 12 is greater than the height of the neck 20 of the element 13, so that the wall 17 extends to the beyond the flat part 18 of the element 13 when the two elements are joined together, defining thus a ring 22 digs beyond the flat part 18.

Furthermore, it will be observed that the outer wall 17 of element 12 present on the side of the flat part 14 a constriction 23 of a height and a diameter exterior such that the housing thus formed can fit, by its constriction, in the ring 22 of the previous box.

Elements of combustible containers according to the invention are obtained, as will be explained in details in the following description, by felting on liquid permeable mold of a suspension aqueous mainly consisting of fibers of nitrocellulose, cellulose fibers and by a resin, so as to obtain a draft of said element, blank which is then compacted and hot cooked. The aqueous suspension may also contain additives to solve the reduction problems of erosion or reduction of oil migration nitrated. Likewise the container elements fuels, once completed, can receive various types of protective coatings or varnishes external agents. However it should be emphasized that characteristically and essential in the sense of the present invention, the felting of said blank is carried out in a single operation, so that the said central collar is an integral part of said element of fuel container. It is remarkable, in the framework of the present invention, that for an element given, the flat part, the neck and the outer wall do not constitute a unique piece with perfect continuity matter.

It is thanks to this characteristic that the assembly of two complementary elements within the meaning of the invention allows the simple and easy constitution of a combustible container housing having a channel central perfectly positioned and stable.

1) dans une première étape on fabrique, comme il sera expliqué plus loin dans la description, par feutrage, compactage et cuisson deux éléments complémentaires de conteneurs combustibles.

2) Dans une seconde étape on remplit l'un des dits éléments avec une poudre propulsive.

3) Dans une troisième étape on rend solidaire de l'élément ainsi rempli le second élément de manière à constituer un conteneur combustible fermé rempli de poudre propulsive et possédant un canal central.

The invention therefore also relates to the use of the elements according to the invention in a process for producing combustible containers loaded with propellant powder for artillery ammunition. This process is characterized in that:

1) in a first step, as will be explained later in the description, two additional elements of combustible containers are made by felting, compacting and baking.

2) In a second step, one of the said elements is filled with a propellant powder.

3) In a third step, the second element is made integral with the element thus filled so as to constitute a closed combustible container filled with propellant powder and having a central channel.

There is shown in Figure 1 a container modular fuel 24 obtained from the elements 1 and 6 shown in Figures 2, 3 and 4. This container 24 was obtained by filling the body case 1 with a propellant powder 25. The filling of an element according to the invention with a propellant charge consisting of powder agglomerated or by a bundle of powder strands linked between them no particular problem whatever the configuration of the element. On the other hand when wants to fill with sprigs of powder not linked together, such as divided strands as described in FR-A-2679992, or with powder grains in bulk, the use of a housing body as shown in Figure 2 turns out particularly interesting. It is in this sense that additional elements 1 and 6 shown in the figures 2, 3 and 4 are the preferred elements of the invention. When the housing body 1 is filled with powder, and it should be observed that it can easily be completely filled, insert the cover 6 as explained more high. In some cases we will coat the exterior surface of the neck 9 and the outer surface of the wall 10 of the cover 6 with a little combustible glue for improve the adhesion of the cover to the housing body. In other cases we may prefer mechanical blocking.

A modular fuel container is thus obtained having a central channel defined essentially by the neck 4 of the housing body 1. Before filling the housing can be drilled in different places to facilitate ignition or combustion.

The presence of a hollow central channel is imperative to ensure good transmission of the ignition of a module to another. In order to further improve ignition, we introduces, in the central channel thus constituted, a complementary hollow ignition tube 26.

In the embodiment shown in Figure 1 this tube additional ignition fuel 26 is supported by the upper end 27 of the neck 9 of the cover 6 and is maintained in contact with the inner surface of the neck 4 of the housing body 1 with a little combustible glue. The additional ignition tube 26 can be formed in one piece or in several sections laid end to end end.

According to a preferred embodiment of the invention the ignition tube 26 is obtained by agglomeration under grain pressure and at a temperature close to 100 ° C. propellant powder coated with a binder based on polyvinyl nitrate according to the techniques described in French patents 2,436,766 and 2,658,505 or in their American correspondents 4,326,901 and 5,174,837. A combustible paper reinforcement tube can also be introduced into the ignition tube 26. The said propellant powder used to form the tube 26 can advantageously be a powder based on nitrocellulose, porous or non-porous, containing possibly additives. The invention thus makes it possible to get rid of any presence of black powder which reduces the risk of corrosion. The tube 26 can also be obtained by agglomeration of powders ignition system for low powders vulnerability.

The invention also relates to a method of manufacturing by felting of container elements fuel according to the invention and in particular elements as shown in Figure 2 which have at the both a long neck and an outer wall very long. Traditional techniques of felting according to which solid deposition is carried out on the outside surface of a mold immersed in a suspension do not allow to obtain cylindrical hollow parts having in their center a central neck of great length which is itself hollow, suction in the central mold cavity corresponding to the said collar allowing only to obtain a full neck, which is not sought in the context of the invention.

To obtain by felting an element blank according to the invention, it is immersed in the suspension of felting a mold having a cavity of revolution consisting of an outer shell and a bottom whose surface is flat, the said bottom having a central column. Said bottom and said column at less are permeable to liquids and suction is exerted inside the mold.

The felting suspension is preferably an aqueous suspension consisting mainly of nitrocellulose fibers, cellulose fibers and by a resin possibly in the presence of a stabilizer like diphenylamine. Such suspension is by example described in patent FR 2,555,302 or in its correspondent US 4 649 827.

FIGS. 6 to 10 show a mold 28 according to the invention.

The mold 28 consists of a central part 29 and an outer part consisting of two shells semi-cylindrical 30 and 31. The central part 29 is connected by a flexible pipe 32 to a vacuum pump while the outer shells 30 and 31 are connected to a vacuum pump by flexible pipes 33 and 34. A loop loop 35 holds the shells 30 and 31 pressed against each other.

With particular reference to the figures 7,8 and 10, we observe that the central part 29 is consists of a cylindrical head 36 crossed by a hollow pipe 37 connected to the pipe 32. The head 36 has a groove on its cylindrical face circular 38. On the lower flat face of the head 36 is fixed by welding a filtration grid permeable to liquids with a circular rim flat 39 welded to the head 36, a first surface vertical cylindrical 40, an annular flat face 41 finished in its central part by a column cylindrical 42 closed by a bottom 43, thus providing a empty space 44 between the head 36 and the grid filtration.

The filtration grid constituting the elements 39, 40, 41 42 and 43 is advantageously constituted by a perforated copper grid covered by a electroformed nickel filter.

Referring now more particularly in FIGS. 7, 9 and 10, it can be seen that the shell 30 consists of a solid semi-cylindrical wall 45 crossed by a hollow pipe 46 connected to the pipe 33. The interior surface of the wall 45 has a rim 47 intended to penetrate into the groove 38 of the head 36 to ensure the positioning of the shell 30 relative to head 36. Under the rim 47, the inner surface of the wall 45 has a flat 48 having a vertical surface 49 and intended for slide under the head 36, the vertical surface 49 of the flat being the same height as the vertical surface 40 of the grid carried by the head 36 and coming into abutment against the latter. At the base of the surface inside the wall 45 is located a second flat 50 having a vertical surface 51, the depth radial of flat 50 being identical to that of flat 48 so that the vertical surfaces 49 and 51 correspond to the same vertical cylinder. On the vertical surfaces 49 and 51 is fixed a grid of semi-cylindrical filtration 52 of the same constitution as the filtration grid carried by the head 36. Thus is formed an empty space 53 between the wall 45 and the grid 52.

The shell 31 is analogous to the shell 30.

When attached to the head 36, the shells 30 and 31 define with the latter a cylindrical mold 28 having a cavity of revolution constituted by an envelope composed by the grids 52, of the two shells 30 and 31, by a flat bottom itself constitutes by the flat face 41 of the grid carried by the head 36 and by a column made up itself by parts 42 and 43 of the grid carried by the head 36.

The mold shown in Figures 7 to 10 is intended to obtain a part as shown in FIG. 2, the envelope formed by the grids 52 being in this liquid permeable case. For obtaining others configurations this envelope may be only partially permeable to liquids.

In the case shown in Figures 7 to 10 the length of the grid 52 between the flats 48 and 50 as well as the length of part 42 of the grid carried by the head 36 will be slightly greater than final dimensions of the element that we want to obtain.

By immersing the mold in a suspension 54 such as previously defined and by vacuuming spaces 44 and 53 we cause the deposit of a blank 55 along the filtration grids. This draft has the general shape of the element 1 represented in FIG. 2, but its hollow neck 4 is closed by the deposition of fibers on the surface 43 of the filtration grid carried by head 36.

When the blank formation is finished, the mold is removed from the aqueous suspension and the blank 55 undergoes a first vacuum dehydration on the mold. Then the shells 30 and 31 are removed and the blank 55 is removed from the mold to undergo a compaction and hot cooking on a baking mold in shape, according to techniques known to man of job. After cooking the element is cut out desired length, which opens the collar central which until then was closed.

The elements according to the invention thus allow just get combustible containers modular for medium and large artillery ammunition caliber which can be completely and easily loaded with different powder geometries propellants on the market.

An example of the implementation of the invention.

Example

We made a combustible case body and a cover according to Figures 2 and 3.

• nitrocellulose : 65,8% en poids
• cellulose : 25,6% en poids
• résine acrylique 7,6% en poids
• diphénylamine : 1,0% en poids
• eau : en quantité suffisante pour une suspension aqueuse à 2,5%

The composition of the felting suspension was as follows:

• nitrocellulose: 65.8% by weight
• cellulose: 25.6% by weight
• acrylic resin 7.6% by weight
• diphenylamine: 1.0% by weight
• water: in sufficient quantity for a 2.5% aqueous suspension

• corps de boitier : longueur : 154 mm
     diamètre extérieur : 158 mm
     diamètre intérieur : 153 mm
     col creux longueur : 151,5 mm
        diamètre extérieur : 30 mm
        diamètre intérieur : 25 mm
• couvercle : hauteur de la paroi extérieure : 15 mm
     diamètre extérieur : 153 mm
     diamètre intérieur : 148 mm
     col creux longueur : 15 mm
        diamètre extérieur : 25 mm
        diamètre intérieur : 20 mm

The dimensions of the rooms were as follows:

• body: length: 154 mm
  outer diameter: 158 mm
  inside diameter: 153 mm
  hollow neck length: 151.5 mm
  outer diameter: 30 mm
  inner diameter: 25 mm
• cover: height of the external wall: 15 mm
  outer diameter: 153 mm
  inner diameter: 148 mm
  hollow neck length: 15 mm
  outer diameter: 25 mm
  inner diameter: 20 mm

We obtained on a series of 50 pieces a satisfactory reproducibility, ie: 5% over the difference mass type, less than 2% of the standard deviation of thickness and less than 1% on the standard deviation of congestion.

The housing body was filled with 2450g of a double base powder (nitrocellulose / nitroglycerin) under shape of cylindrical grains with 19 holes of potential 900 cal / g or 3780j / g (or 2700g of this same powder under divided strands).

We introduced into the central channel of the container thus constituted an ignition tube obtained from a coated nitrocellulose single base porous powder by 3% of binder or polyvinyl nitrate.

This tube has an apparent density of 0.77 g / cm ³ .

It consists of two cylindrical sections identical length 76 mm, outer diameter 25 mm, internal diameter 15.4 mm.

Each section was obtained from 18 g of coated porous powder.

These sections were placed in a pressure bomb of volume 156 cm ³ with a loading density of 0.10.

• force : 1 MJ/kg,
• temps d'inflammation : 3,6 millisecondes,
• temps de combustion : 2,1 millisecondes.

The bombing results were as follows:

• force: 1 MJ / kg,
• ignition time: 3.6 milliseconds,
• burning time: 2.1 milliseconds.

In a 3745 cm ³ volume fire simulator, a combustible container was introduced as described above loaded with 19-hole powdered grains.

• densité de chargement : : 0,687
• pression maximale atteinte à la rupture de l'opercule : 60 MPa
• augmentation moyenne de la pression : 6x10-³MPa/ms (ms=milliseconde)
• délai d'allumage : 78 ms
• temps de combustion : 3,2 ms.

The firing results were as follows:

• loading density:: 0.687
• maximum pressure reached at the rupture of the cover: 60 MPa
• average pressure increase: 6x10- ³ MPa / ms (ms = millisecond)
• switch-on delay: 78 ms
• burning time: 3.2 ms.

Claims (9)

1. Combustible container component (1) comprising a hollow central channel, for artillery ammunition, obtained by felting on a mould which is permeable to fluids, of an aqueous suspension consisting mainly of nitrocellulose fibres, cellulose fibres and a resin, such as to obtain a blank for the said component which is then compacted and baked, characterised in that the said component (1) has at least one substantially flat revolution part (2) which has a circular central aperture (3) edged by a hollow cylindrical central neck (4), and in that the said blank is felted in a single operation.
2. Combustible container component according to claim 1, characterised in that the said flat revolution part (2) is edged by a cylindrical outer wall (5) which is disposed on the same side as the said central neck (4).
3. Combustible container component according to claim 2, characterised in that the said outer wall (5) has a height which is substantially the same as the height of the said central neck (4).
4. Combustible container component according to claim 2, characterised in that the said outer wall (21) has a height which is different from the height of the said central neck (20).
5. Use of components according to any one of claims 1 to 4 in a method for producing filled combustible containers for artillery ammunition, characterised in that:

   1) two complementary components (1,6) of combustible containers are produced by felting, compacting and baking;

   2) one of the said components (1) is filled with a propellant powder;

   3) the component thus filled is rendered integral with the second component, such as to constitute a combustible container (24) which is filled with powder and has a central channel.
6. Use according to claim 5, characterised in that an ignition tube (26) is inserted in the said central channel.
7. Use according to claim 6, characterised in that the said ignition tube (26) is obtained by bonding grains of propellant powder which are coated with a binder based on polyvinyl nitrate.
8. Method of production by felting of a blank (55), from components according to any one of claims 1 to 4, characterised in that there is immersed in the said suspension a mould (28) which has a revolution cavity consisting of an envelope (52), and a base (41) which has a flat surface and a central column (42, 43), the said base and the said column being permeable at least to fluids, and being maintained spaced from the inner walls of the mould such as to form at least one empty space (44), and in that suction is applied to the interior of the empty space (44).
9. Method according to claim 8, characterised in that the said outer envelope (52) is at least partially permeable to fluids, and delimits an empty space (53) in which a vacuum can be created.

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