EP2462401B1 - Combustible propellant charge casing - Google Patents

Description

The invention relates to a combustible sleeve for receiving propellants, ammunition formed with such a sleeve and a manufacturing method for such sleeves.

Pods have long been known as a component of ammunition for both small-caliber weapons and large-caliber weapons and are widely used. They are mainly used to hold the propellant charge powder. Usually, sleeves have a circular cylindrical and elongated hollow shape; the actual shell is referred to here as a shell wall.

To produce a cartridge, the sleeve is usually equipped with an igniter comprehensive bottom. This is usually made of metal, usually steel. To produce a cartridge, a projectile is additionally placed on the still free, the bottom opposite longitudinal end of the sleeve.

Also burnable sleeves are known in principle. They burn or consume as a result of firing. If this happens sufficiently residue-free, no need to remove sleeve remains before the next shot. Ideally, only the bottom is ejected.

In combustible sleeves so a residue-free combustion is desirable to avoid additional cleaning of the cargo space or the barrel.

It is known to make combustible sleeves of nitrocellulose and pulp; usually with additives such as binder resin and stabilizers. Conventionally, a screen mold is dipped vertically into an aqueous pulp of nitrocellulose and pulp for production. With the help of negative pressure, the sieve mold sucks the pulp; it forms a wet raw felt. Basically, this material can also be referred to as "fleece". However, the term "raw felt" has prevailed here. The raw felt is pressed to achieve the final geometry and dewatering and at least temporarily heated.

The sleeves must have a certain mechanical stability. A slight deformation may be tolerable, but no crack may form. A crack could cause propellant powder to escape - a safety risk that will not be tolerated. According to some specifications, the sleeves are therefore designed with an additional, inner bag for holding the propellant charge powder, a so-called powder bag.

The stability of the sleeve is particularly relevant for tank ammunition, since here the requirements for mechanical stability can be very pronounced, for example by the handling within the tank as well as by loads and movement shocks when attaching the cartridge. However, the invention is not limited to tank ammunition.

The DE 30 08 996 A1 shows a method for producing combustible sleeves. It is proposed to roll fabric inserts into the raw felts during the felting process. It has been found that a sleeve thus produced can dissolve in an impact in several parts. The felt can be detached from the inserted tissue over a large area. At worst, the sleeve is divided into three separate components, namely the fabric insert and the raw felt, which has detached from the inside and the outside of the fabric.

The DE 36 19 960 A1 shows a combustible sleeve with additional stiffeners made of metal or plastic. These stiffeners can be embedded in the sleeve or even attached to it. If the stiffeners are embedded in the sleeve, then they are provided with holes, so that the rest of the sleeve can burn through these holes. The stiffeners themselves, however, do not burn.

In US 3,747,532 is a sleeve of nitrocellulose described. Several superimposed layers of a nonwoven fabric are bonded by nitrocellulose as an adhesive.

In DE 2 058 539 For example, a method of manufacturing a nitrided cellulose container having a lightweight fabric weave reinforcement is described.

In DE 1 578 082 an ammunition sleeve is described from a mitverbrennendem in the explosion of the charge powder material.

In US 3,901,153 there is described a combustible sleeve comprising multiple layers of entangled combustible material.

Starting from the DE 30 08 996 A1 the invention has for its object to provide a mechanically robust and residue-free combustible sleeve for receiving propellants. The task also relates to a corresponding manufacturing method and to corresponding ammunition.

The object is achieved by the features of claim 1, in particular by a sleeve for receiving propellants with a shell wall of combustible entangled fiber material and an insert of intersecting threads in the shell wall, the threads so from each other spaced, that entangled fiber material passes through the areas between the threads.

The invention is based, as already shown above, on the observation that the components of the combustible sleeves according to the doctrine of DE 30 08 996 from each other, as well as on the statement that the sleeves after the DE 36 19 960 can not burn without residue; In this teaching was dispensed in favor of the stability of a residue-free combustion.

Furthermore, the invention is based on the finding that in the first-mentioned teaching from the prior art, the tissue prevents an intimate continuous connection of the fiber material and thus favors a falling apart of the sleeve.

The invention is also based on the observation that filaments can be combustible and still provide stability, as well as on the idea to achieve mechanical stability on the insertion of threads, but to choose the distances between the threads so large that the felt is a unit remains; that is not severed over a large area - in contrast to the prior art, where the fabric due to the close-fitting threads, warp and weft, the felt extensively severed.

The success of the invention is mainly due to the penetration of the fiber material by the distances between the threads. In other words, a layer formation in the felt of the sleeve is avoided.

Since the insert promotes the mechanical robustness of the sleeve, one can also speak of a "reinforcement".

The sleeve according to the invention thus basically consists of fiber felt, in which a reinforcement is additionally embedded. As a result, fibers penetrate through the reinforcement. The sleeve would be dimensionally stable even without the reinforcement, although not as robust and unbreakable as possible according to the invention.

The threads of the insert are basically at an arbitrary angle one above the other.

In particular, the threads may be orthogonal to each other.

The threads may be made of cotton or carbon fibers, for example. Desirable is a comparatively high tear resistance and at least temporary heat resistance. Namely, during the raw felt production, the material is heated to about 135 ° C for a few minutes, usually 5 minutes. This temperature should be able to withstand the threads without damage and still be combustible residue-free within the meaning of the invention. Preferably, the threads may even be exposed to a temperature of over 140 ° C for 5 minutes without adversely affecting their mechanical properties. Preferably, the threads are also relatively thin compared to the thickness of the shell wall, so that the insert does not cause a higher wall thickness.

The term "residue-free" is not to be understood here as absolute, but interpreted according to the requirements of the practice. A sleeve burns within the meaning of the invention without residue when ammunition can be reloaded without first freeing the cargo space of tube remains.

Overall, therefore, a robust and residue-free combustible sleeve is specified. In particular, the insertion of a powder bag may be unnecessary. Basically, sleeves according to the invention may optionally be made even thinner than conventional sleeves - and with the same mechanical robustness. This would have the advantage that more propellant charge powder can be used and thus the performance of the ammunition can be increased. The invention counteracts any escape of propellant charge powder, possibly even in the event of breakage or damage to the jacket.

According to the independent claims 1 and 4, the threads form a net, so that the fiber material passes through the mesh of the network.

To form the network, the threads can be connected to each other about nodes. However, they can also be connected to each other in other ways, such as over welding points or with the help of glue.

Preferably, a cotton net is used as the insert. Corresponding nets are cheap and prefabricated as fishing nets, for example.

According to the independent claims 1 and 4, the network is repeatedly fully inserted along the circumference of the jacket wall of the sleeve. Weak points in the shell wall can be avoided. The insertion of the network can be done, for example, by winding, insofar as one can speak of the linguistic simplicity of windings.

It is particularly preferred if the net is wound around 360 ° five to eight times. In principle, a higher mechanical stability is to be expected with increasing number of windings. In general, however, it is not desirable that the thickness of the shell wall of the sleeve increases. Therefore, the number of windings of the network is limited in particular by the desired wall thickness. This is especially the case when the net is knotted because the knots have a certain thickness.

If the threads of the mesh do not burn as well as the fibrous material of the shell, it may also be useful to limit the number of turns to further ensure that the shell burns without residue.

Especially proven are eight windings.

The net is wound up during the deposition of the raw felt during its formation.

This results in a spiral insert in the shell wall. Corresponding sleeves are advantageously produced by the manufacturing method described below.

Preferably, the spiral windings are spaced apart from each other so far that the flat sides of the network are at least partially separated from each other by the fiber material of the jacket wall. This prevents the threads of different windings from lying directly against each other, which could provoke mechanical weaknesses.

The meshes of the mesh preferably have a width of 7 to 20 mm, more preferably 10 to 18 mm, particularly preferably 10 to 15 mm.

This width has proven itself for the relevant types of ammunition. If the mesh size is too small, the fiber material can not reach sufficiently through the meshes to ensure a satisfactory cohesion of the felt. If the mesh size is too large, the mechanical stability of the sleeve is not satisfactorily supported. The ideal mesh size may depend not only on the geometry of the sleeve but also on the properties of the fiber material. In particular, it is preferred that pulp fibers, which typically have a length of 2 mm to 4 mm, can easily reach through the meshes.

The invention also relates to a method for producing a sleeve according to the invention. This method comprises at least the following steps: making a shell wall of combustible entangled fibrous material and inserting a liner of intersecting filaments into the shell wall, the filaments being spaced apart such that entangled fibrous material passes through the regions between the filaments.

In the manufacturing process, a screen mold for forming the sleeve is aligned horizontally along its axis of rotation. The screen is immersed at least in sections in a pulp with the fiber material. The fiber material is sucked in by means of negative pressure, so that a raw felt attaches to the screen.

So that the concentration of the fiber material in the aqueous pulp can be kept constant, the screen form is to be immersed in a circulating pulp - in contrast to a trough without open inlets and outlets, in which only a limited amount of fiber material is present.

According to independent claim 4, the net is wrapped during the attachment of the fiber material in the resulting raw felt. This results in itself a spiral insert, in which the individual windings of the network are separated by fiber material.

Preferably, the net is unwound from a supply roll. This is particularly simple in terms of production technology.

At the beginning of the winding, the loose end of the net can be attached to the resulting raw felt on the screen form. Under favorable production conditions, the net has become so intensively associated with the resulting raw felt after only 60 ° of rotation that the supply roll for the net can be unwound solely by further turning the sieve shape.

Preferably, the propellant charge powder is filled without inserted powder bag. This not only saves effort and costs in production, but also allows to introduce a little more propellant powder.

The preceding and following description of the individual features relates to the sleeve as well as to the manufacturing method and the ammunition, although this is not explicitly mentioned in any case in detail; The individual features disclosed in this case can also be essential to the invention in combinations other than those shown. Preferred embodiments are also indicated in the dependent claims.

• Figur 1 zeigt schematisch den unteren Teil einer erfindungsgemäßen Kartusche im Längsschnitt.
• Figur 2 zeigt einen Schnitt durch ein Schema einer Produktionsanlage zur Durchführung des erfindungsgemäßen Herstellungsverfahrens.

In the following, the invention will be explained in more detail with reference to exemplary embodiments, without wishing to restrict the invention to the examples:

• FIG. 1 schematically shows the lower part of a cartridge according to the invention in longitudinal section.
• FIG. 2 shows a section through a scheme of a production plant for carrying out the manufacturing method according to the invention.

FIG. 1 shows a sleeve 6 according to the invention as part of a cartridge according to the invention 1. The sleeve 6 is elongated and circular cylindrical and receives in its interior the propellant charge powder 4. In the jacket wall of the sleeve 6, a network 5 is inserted.

At the lower end of the cartridge 1, a bottom 2 made of brass with an igniter 3 is attached.

The sheath 6 is made of felted pulp and nitrocellulose fibers as well as conventional additives.

The inserted net 5 is a cotton fishing net 5 with orthogonal knotted threads. The threads are 0.2 mm thick and have a strength of 40 Nm.

The matted fiber material passes through the 15 mm wide meshes of the net 5. The net 5 is wound eight times around a 360 ° spiral. Between the individual windings sufficiently entangled fiber material is present in order to separate the individual windings from one another.

FIG. 2 shows a production plant for sleeves according to the invention for carrying out the manufacturing method according to the invention in cross section.

The production plant has at least a screen 20, a supply roll 21 and a trough 22 with an aqueous pulp 23. The horizontally oriented screen 20 is immersed with a lower portion in the aqueous pulp 23. Pulp fibers and nitrocellulose fibers float in the aqueous pulp in particular. In order to keep the concentration of the fiber material constant during the production process, the aqueous pulp 23 is constantly renewed by a corresponding flow.

In the screen 20, a negative pressure is generated so that this fiber material sucks from the pulp 23. The screen 20 rotates slowly, for example, five times per minute, so that forms a raw felt along its surface. The direction of rotation is indicated by the arrow A. A net 5 is applied to the resulting raw felt (the raw felt itself is not shown in the figure). The net 5 is unrolled from the supply roll 21. The rotation of the supply roll 21, indicated by the arrow B, results, mediated via the net 5, by the rotation of the screen 20.

As soon as the net 5 is wrapped in the raw felt over about 60 °, it may already be able to stand on its own.

While the raw felt is further deposited, the net 5 is wound eight times over 360 ° in the raw felt. Since fibrous material continues to accumulate during winding and the raw felt grows, fiber material also collects between the windings of the net 5 The raw felt with the inserted net 5 is subsequently pressed and heated at 135 ° C. for about five minutes.

Claims (4)

1. A case (6) for accommodating propellant charge powder (4)
   with a jacket wall of combustible felted fibrous material (23) and
   an inlay (5) of intersecting threads (5) in the jacket wall, wherein
   the threads (5)

   - are spaced from each other such that felted fibrous material (23) reaches through the regions between the threads (5), and

   - form a net (5), so that fibrous material (23) reaches through the meshes of the net (5), and wherein

   the net (5)

   - is completely inserted along the circumference of the jacket wall several times, and

   - is spirally inserted into the jacket wall and in which the flat sides of the net (5) are at least partly separated from each other by the fibrous material (23) of the jacket wall.
2. The case (6) according to claim 1, in which the net (5) is made of cotton.
3. The case (6) according to claim 1, in which the meshes of the net (5) have a width of 7 mm to 20 mm.
4. A method for producing a case (6) according to any of claims 1 to 3, with the following steps:

   fabricating a jacket wall of combustible felted fibrous material (23), and

   inserting an inlay (5) of intersecting threads (5) into the jacket wall which are spaced from each other such that felted fibrous material (23) reaches through the regions between the threads (5),

   wherein a screen mold (20) is at least partly immersed into an aqueous pulp (23) with the fibrous material (23),
   by negative pressure, fibrous material (23) is sucked in for forming a raw felt on the screen mold (20) and thereby is attached,
   the screen mold (20) is rotated, and
   the axis of rotation of the screen mold (20) is oriented horizontally, and wherein
   the threads (5) form a net (5), so that fibrous material (23) reaches through the meshes of
   the net (5) and wherein the net (5) is wound into the raw felt formed, while the fibrous material (23) is attached, and wherein the net (5) is completely wound around the circumference of the screen mold (20) several times and wherein the net (5) is spirally wound into the raw felt formed and between the windings of the net (5) fibrous material (23) from the aqueous pulp (23) is attached.

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