Description
[0001] Subject-matter of the invention is a projectile, in particular an Ar- mor Piercing Incendiary (APT) projectile or an incendiary projectile, comprising a composite material, in particular wherein the projectile tip is made of the com- posite material, and a corresponding manufacturing method.
[0002] API projectiles have long been state of the art and are described, for example, in US. 10 1380773 A. They are used to mark hits by light and to set flammable objects on fire. Thus, when a projectile strikes, it should emit a flash of light. Four different systems are particularly well known: These include the Frangible Armor Piercing (FAP) system, an ammunition which has a multi-part structure consisting in particular but not exclusively of metal powder. This metal powder (titanium or zirconium) is embedded in epoxy resin, thus forming a combustible part that emits a bright light on impact (as in US 5299501 A, for example).
[0003] Pyrotechnic systems are widely used with larger calibers (military medium caliber). They contain a pyrotechnic charge which is initiated on impact and emits a bright light. These pyrotechnic compositions usually consist of a proportion of magnesium or aluminum and a proportion of oxygen suppliers in solid form (see for example US 3028808 A).
[0004] In military small caliber ammunition, systems are known which — contain exclusively a fuel (e.g., in US 4112846 A). The small caliber API ammuni- tion is provided with a tip, which is constructed of titanium and is often ma- chined from solid. This titanium tip is heated by friction on impact. This fric- tional heat is sufficient to ignite the titanium. Since titanium burns under a bright flame, this achieves a precise target-dot marking.
[0005] In addition to target point marking, items that are easily ignited can also be intentionally set on fire.
[0006] Multi-purpose projectiles are also considered pyrotechnic systems, — but, in addition to luminous pyrotechnics, also include a set that explodes. This achieves a combination of target point marking, incendiary, shrapnel production and penetration effect. However, this type of projectile has the major disad- vantage that the required multilayered structure is also associated with relatively high manufacturing costs (US 2564870 A).
[0007] From EP 2 295 927 A2 a missile with a pyrotechnic set is known.
[0008] From US 2012/0167793 A1, projectiles with fire or explosion re- sistant composite materials are known. From US 2012/308426 A1 a disassembly projectile is known that comprises a composite material that contains a metal powder and a polymer matrix.
[0009] API projectiles in the small caliber field are usually constructed in three parts. The shoe consists preferably of a brass alloy rotating part. This shoe is in contact with the barrel. Therefore, a high ductility is required. The shoe must not damage the steel barrel. A hard core is inserted in the center of a pref- erably designed projectile. This consists of a steel or tungsten alloy. The purpose of the hard core is to ensure penetration.
[0010] The incendiary portion in these projectiles is provided by the tita- nium tip. The titanium tip is usually made of solid material and often has a rela- tively complex structure, since it is located at the tip and must still provide enough space for the long hard core. However, it is also conceivable to manufac- ture incendiary projectiles without a hard core. In addition, the structure in solid titanium is questionable from a market-economy point of view, since the materi- al properties of the relatively expensive pure titanium are not exploited in any way. Neither ductility nor low density are decisive for the incendiary effect. The excellent corrosion resistance is also of only secondary relevance. Due to the partly complicated internal geometry, the volume that has to be removed by ma- — chining is relatively large. The reason for using the material is its flammability.
[0011] The present invention was therefore based on the object of finding a material that is more cost-effective and a process that is more material-saving. In the production of titanium and also magnesium into a semi-finished product, — the starting material consists of a slurry-like structure that can be easily pro-
cessed into powders. This is also the reason why the powders (precursor materi- al) of the respective materials are comparatively inexpensive. According to in- vention, it is therefore particularly optimal to use a method in which the tips of the projectiles are made in such a way that powder material can be used. This reduces waste significantly, although the contours can still be complex. In the production process, the matrix of the composite material can be used to perma- nently bond the pieces of projectile shoe and core together. To keep the projectile as inexpensive as possible, the tip should be available directly in the previously defined and desired color without the need for an additional dyeing process.
[0012] The invention is a projectile according to claim 1 and a method ac- cording to claim 8.
[0013] In the projectile to be protected, the unfavorable material utiliza- — tion is solved by embedding a metal powder, preferably titanium or magnesium powder, in a polymer matrix. The polymer composite can be formed by injection molding or other suitable molding processes. A thermoplastic is used as the ma- trix polymer.
[0014] Hereby, the metal powder fulfills the function of the incendiary, the matrix serves as a carrier and at the same time as a fastening material for the other two parts (hard core and projectile shoe). Also, a connection between the main projectile and the polymer composite material is conceivable, but this can only be considered for the incendiary variant.
[0015] Through orienting tests, it was found that surprisingly, it is suffi- cient to use a metal-polymer composite to generate the desired light effect. The polymer-metal composite consists of at least 50 percent by volume of a metal powder. The metal powder is selected from the group
[0016] consisting of titanium, magnesium, aluminum, zirconium or any mixtures thereof, preferably the metal powder consists of titanium or magnesi-
um. The polymer matrix preferably consists of a thermoplastic industrial plastic, for example polyether- terketone (PEEK) or another industrial plastic. PEEK is particularly suitable for use because of the wide temperature range in which the product can be used.
[0017] According to the invention, the tip of the projectile is injected di- rectly onto the projectile shoe and the hard core. In order to achieve an improved connection, the projectile core and the projectile shoe can be provided with a rough surface, notches or radial grooves. Ideally, the precursor piece, comprising a projectile shoe with a core located therein, are inserted into the injection mold and recast from the tip. This simplifies or eliminates several work steps, for ex- ample, the pressing in of the core with a pressing machine is no longer necessary. The placement of the projectile tip is also eliminated, and the injection molding of the projectile tip eliminates the need for an additional seal.
[0018] In one embodiment, a modular design may be contemplated. The separately produced polymer composite projectile tip may be attached to the precursor with a snap lock, a bayonet lock or a press lock. This makes decentral- ized production possible. An embodiment with a projectile tip configuration that can be changed shortly before use is also possible. In a particularly noteworthy embodiment, it is possible to selectively use a plastic tip without metal content or a tip with different mixtures. Thereby, a single projectile design can be used ei- ther as AP ammunition or API ammunition.
[0019] Industrial plastics are available in different colors as granules. Thus, a simple marking and color adaption is possible. As metal powder grain — sizes from 0,02 mm to 0,4 mm are suitable. In principle, only a small amount of metal waste is produced. This makes the design economically and ecologically valuable.
[0020] The functional principle for the light flash is explained as follows. — Due to the short-time dynamic impact of the tip, the plastic reacts brittle frac- ture-prone, so that the plastic-metal composite breaks similar to a ceramic. This releases the metal powder particles. The particles are additionally heated up by the impact friction and, in the case of magnesium, for example, ignite themselves after a very short time. Although the titanium requires more energy until the self-ignition temperature is reached, which is why the fire pattern changes, igni-
tion on impact is still possible.
In the case of metal powder mixtures, therefore, a desired effect can be achieved, for example flame coloring through the addition of other elements is conceivable.
Alkali and alkaline earth metals, which often exhibit a characteristic flame coloration, are particularly suitable for this pur- 5 — pose.
Particularly suitable are additions of potassium, sodium, barium, calcium, lithium, boron and strontium.