Hollow Charge, or Plate Charge, Lining and Method of Forming a Lining

The invention relates in general to ammunition and in particular to a new and useful hollow charge, or plate charge, lining, or a projectile charge coating and to a method of making it.

Such explosive charges provided with a mostly conical cavity having a cone angle of selected ranges and located substantially at the projectile side directly facing the target, as known in a variety of designs.

For example, German No. OS 29 13 103 discloses a flat cone charge with a cavity which is aligned with a metal insert made of an alloy having such a high tantalum content that a density is obtained exceeding that of copper. Tungsten and various other alloy metals also are provided for that alloy. Experience has shown, however, that due to the considerably different properties of the employed metals, these prior art copper alloys exhibit a relatively insufficiently homegeneous density and structure, reducing the piercing capacity of the explosive charge.

It is known that the surface texture of a hollow or plate charge lining considerably influences the cutting power or cutting depth, so that surface roughness, variation in thickness, oxide films, etc. are undesirable. As a remedy and to obtain a material easy to work for the mentioned purposes, German Pat. No. 27 24 036 shows the manufacture of an insert in a pressing process, of a copper bismuth alloy. However, the same applies to this method as above, namely that no satisfactory homogeneity is obtained.

The present invention is directed to a lining or coating material for explosives which is homogeneous and leads to an improved penetration.

This problem is solved in a surprisingly reliable manner by providing the features set forth in the claims.

In the following, embodiments are described and explained.

The cutting power and cutting depth of a hollow charge is given in a first approximation by the sum of the spike lengths at the crater bottom multiplied by the root of the ratio of the lining material density to the target material ##EQU1## It results from this formula that by employing a heavy metal, such as tungsten having a crystal density of 19.2 grams per cm.sup.3, a considerably better penetration depth can be obtained, as compared to copper having a density of 8.9 gram per cm.sup.3. Only, pure tungsten material cannot be worked as a homogeneous lining to the required wall thickness of 0.5 to 3 mm. That is why tungsten-copper alloys have been considered. However, these alloys still do not satisfy the desired performance data.

For this reason, the invention provides a lining or coating made from a composite material formed of tungsten and copper. The individual tungsten grains are agglutinated with the copper to a homogeneous structure by means of a binder, such as nickel or palladium. The ductility of copper is thus combined with the heavy tungsten particles to a spike of high density, and a material with optimum properties for this purpose is obtained.

The tungsten proportion should range between 50% and 95%, and the homogeneous compound material obtained by pressing, sintering, and repressing with copper should be finish-formed to the desired shape. According to experience, a tungsten proportion of 60% to 80% results in an optimum material suitable for many applications. In this case, the tungsten particles are embedded as a matrix in copper.

Another possibility of obtaining the composite material is to isostatically compress tungsten powder and copper powder along with the binder, for example nickel or palladium, under a high temperature exceeding the melting point of copper.

Still another method provides a mechanical compression of pure tungsten material with suitable binders, followed by a sintering process, and in a second operating step, infiltration of the copper proportion, with again pressing the material directly to the desired shape. This saves not only material but also operating time.

While specific embodiments of the invention have been shown and described in detail to illustrate the application of the principles of the invention, it will be understood that the invention may be embodied otherwise without departing from such principles.

Further it is proposed that the grain size of tungsten for the composite material ranges from between 2 microns to 90 microns. The grain sizes of the tungsten ranges from 30 to 60 microns showed to be most favourable.