DE2458877C2 - Combustible protective cover against thermal influences for projectile propellants for automatic weapons - Google Patents

Description

The invention relates to combustible protective covers against thermal influences for propellant projectile charges for automatic weapons based on a polyurethane foam.

Combustible cartridge cases based on a synthetic resin foam, inter alia. based on Polyurethane foam are from DE-AS 2136 750 known their combustibility and, above all, mechanical resistance in automatic weapons practical requirements are not always sufficient.

The object of the invention are therefore combustible protective covers, which are better, i.e. faster and have more complete combustibility and their better mechanical strength allows complete ss Manufacture protective covers without a metallic base or other mechanical reinforcements.

This object is achieved according to the invention in that the protective cover consists exclusively of polyurethane foam, which contains up to 80% of one or more μ secondary explosives with a good oxygen balance and melting points of more than 2ÖÖ ⁵ C and that the protective cover has a density of 0.4 to 1, 2 g / cm ³ .

From US-PS 32 57 948 sleeves for artillery shells are known, which are made of a thermosetting resin, u.; i. Made of polyurethane foam, with a cellular structure besiL'hen. These sleeves have the disadvantage that they do not burn completely and are therefore only suitable for large-caliber projectiles.

From US-PS 37 30 094 protective coatings for unprotected sleeves or fuel pellets are known to be made from a temperature-resistant explosive, preferably organic nitrogen compounds and an organic binder. These protective layers do not have a foam structure and show insufficient mechanical strength

Caseless ammunition usually consists of one compact body consisting of pressed and / or glued powder elements When in use of these two types of propellant charges in large-caliber weapons with low rate of fire, in which at the Walls of the combustion chamber no permanent extremely high temperatures occur, is sufficient than Thermal insulation generally a layer of varnish which at the same time has the task of counteracting the powder charge To protect moisture.

When Verschuß this ammunition into an automatic weapon with a high shot cadence temperatures occur on the walls of the combustion chamber of 300 ⁰ C and more. In order to prevent uncontrolled ignition of the propellant charge, the flammable sleeve or the powder compact must be provided with a protective cover that isolates it so that, for. B. if the fuse fails, there is enough time to remove the ammunition from the combustion chamber. The basic condition for the protective cover is that it burns completely and with as little smoke as possible

Experiments with unprotected sleeves or Treibstoffpreßlingen have shown that the use of nitrocellulose or nitrocellulose-nitroglycerine masses at 215 "C decomposition after about 120 lake used by increasing the temperature to 250 ⁰ C, the decomposition starts after about 20 see and at 300 ⁰ C after 2 see this time would not be sufficient to unload the weapon.

With the present invention, the residence time of the powder charge at 300 "C in the combustion chamber can be increased by 15 to 30 times and at the same time better mechanical strength can be achieved. The protective covers according to the invention consist exclusively of polyurethane foam, which contains up to 80% of one or more secondary explosives contains a good oxygen balance and melting points of more than 200 ° C and has a density of 0.4 to 1.2 g / cm ⁵ .

Preferably, carbonated foamed polyurethanes are used and to improve the Oxygen balance in limited quantities (to avoid smoke formation) inorganic oxygen carriers incorporated into the protective layer. When using potassium nitrate, muzzle flash is achieved at the same time

The foam cover can be applied in a uniform thickness of 03 to 2.0 mm with a density of 0.4 to 1.2 g / cm ^J depending on the proportion of the secondary explosive, but it can also be provided with 6 to 8 ribs, the one Can have a thickness of up to 2.0 mm.

The foaming takes place in molds that are worked out according to the desired surface structure. The foam layer can subsequently be applied to the Combustible sleeve or the powder pre-oil can be applied, but it can also be produced beforehand and incorporating the sleeve or pellet.

According to the invention, nitroguanidine is preferably used as the secondary explosive. Ammonium picrate, rlexa-

nitroosanilide, TriniiiJüiaminobeiuc !, Octogen and Hexanitrostilbene used.

example 1

Protective cover

Polyurethane foam
Octogen
Foam density
Foam thickness, evenly
Residence time at 300 ⁰ C to
for decomposition:

Example 2

Protective cover

Polyurethane foam

Hexonitrostilbene

Potassium nitrate

Foam density

Foam thickness,

ari the ribs

between the ribs
Residence time at 300 ⁰ C to
for decomposition:

40% 60%

0.6 g / cm ³

0.5 mm

35 seconds

30% 60% 10% 0.8 g / cm ³

\ 2 mm 0.4 mm

40 seconds

10

15 protected from the effects of exposure

It has been shown that with these casings, the weight of which can make up 50% of the total propellant charge, good ballistic results with favorable thermal efficiency can be achieved.

The production of such sleeves is technically easy to carry out; they can be carried out on injection molding machines such as those in are common in the plastics industry.

Example 3

Protective cover at the same time combustible case for mm ammunition

Combustible sleeve:

Wall thickness
density

Total propellant charge:
(Sleeve + powder)

20th

25th

The usual combustible sleeves can also completely pass through the protective cover according to the invention made of plastic foam and secondary explosives can be replaced by adhering these to 2 to 15 mm the density given above.

The result is a combustible shell without heat-sensitive nitric acid esters, with good mechanical strengths and good thermal resistance. The powder in the case is excellent against heat and moisture bullet weight
Initial floor speed:
Maximum gas pressure:
Total energy:
Muzzle energy:
Thermal
Efficiency:

40% polyurethane 60% octogen 4.5 mm 0.65 g / cm ³ 21% polyurethane 32% octogen 47% double-base

Propellant 220 g

1200 m / s 4100 bar

422KJ

164KJ

38.9%

The well-known weight and volume savings of the combustible case and the caseless ammunition - or 20% - compared to the classic ammunition with a metal case, is also given in Example 3 Arrangement achieved.

1 BIaU drawings

Claims (7)

Patent claims: 1. Combustible protective cover against thermal influences for projectile propellants for automatic weapons, based on a polyurethane foam, characterized in that the protective cover consists exclusively of polyurethane foam, which contains up to 80% of one or more secondary explosives with a good oxygen balance and melting points of more than 200 ° C, and that the protective cover has a density of 0.4 to 1.2 g / cm ³ 2. Protective cover according to claim 1, characterized in that it is used as a secondary explosive nitroguanidine, ammonium picrate, hexanitroxanilide, trinitro contains diaminobenzene, octogen or hexanitrostilbene. 3. Protective cover according to claims 1 or 2, characterized in that up to 30% of the Secondary explosive is replaced by an oxygen carrier, such as KaliuiEÜtrat 4. Protective cover according to claims 1 to 3, characterized in that it has a thickness of 03 to 2.0 mm on combustible sleeves or caseless ammunition is applied 5. Protective cover according to claims 1 to 4, characterized in that it has a uniform Having thickness 6. Protective cover according to claims 1 to 4, characterized in that it has ribs is provided whose thickness can be twice as great as the layer lying between the ribs 7th Protective cover according to claims 1, 2, 3 and 5, characterized in that it is in the form of an injection-molded sleeve with a wall thickness of 2 to 15 mm is present and at the same time represents the container for receiving the propellant charge