EP1940574B1 - Method for producing a penetrator - Google Patents

Abstract

The invention relates to a method for producing a penetrator (10) from a tungsten heavy metal with a high fraction of tungsten and an outer sheath (7), which consists of a material that is more ductile in relation to the penetrator core (6). To produce a penetrator (10) of this type in a cost-effective manner, according to the invention a twin-hopper filling device, which corresponds to the dimensions of the penetrator core (6), is introduced concentrically into a compression mould (1) that corresponds to the outer dimensions of the penetrator (10). The inner pipe (3) is filled with a first tungsten powder blend with a high fraction of tungsten for producing the penetrator core (6), whilst the annular gap between the outer wall of the inner pipe and the inner wall of the compression mould (1) is filled with a second tungsten powder blend with a lower fraction of tungsten, (approximately between 85 % and 91 %), than the first powder blend. Once the inner pipe (3) has been removed from the compression mould (1), the powder blend is then compressed in the known manner to produce the penetrator (10), the compressed body is subsequently sintered and cold-formed and the penetrator slug is finally finished.

Description

The invention relates to a method for producing a penetrator with a tungsten heavy metal (WSM) penetrator core with a high proportion of tungsten and an outer jacket which consists of a material that is more ductile than the penetrator core.

Tungsten-heavy metal alloy penetrators typically have a high tungsten content (90 to about 97% by weight), because of their high masses, these materials have good penetration performance on normal impact on simple armored targets. However, the high proportion of tungsten leads to embrittlement of the material, so that it often comes before the penetration of the target, a breakup of the penetrator with obliquely arranged targets and multi-plate targets. The kinetic energy of the resulting relatively short fragments is usually insufficient due to their low mass to penetrate the remaining target plate (s).

The brittleness of well-known WSM penetrators often increases in that, during mechanical processing, for example by turning or grinding, cracks of the near-surface tungsten grains occur, which can then lead to premature failure of the respective penetrator under load propagation through crack propagation.

From the DE 41 13 177 C2 It is known to increase the strength of machined penetrators, the outer tungsten layers of the respective machined in its geometry penetrator by etching. It has been found that such an etch of the outer tungsten layers substantially (ie, up to 20%) increases the impact value of the corresponding penetrator.

A disadvantage of this known method, however, that acids must be used, which are ahwendungs- and environmentally unfriendly. In addition, the production of such penetrators is relatively expensive, because the predetermined dimensions of the penetrator may not be affected by the etching process.

From the DE 40 16 051 C2 Furthermore, a penetrator is known in which a fracture-sensitive penetrator core consisting, for example, of tungsten heavy metal is protected by means of a ductile sheath. For this purpose, the ductile casing, which consists for example of steel, is applied to the penetrator core in a form-fitting manner after the tungsten core has been produced by pressure-rolling. This known method is relatively time consuming and expensive.

The AT 383 979 B In turn, proposes a method of making penetrators for subcaliber balancing projectiles and casing for use in the practice of this method. In this case, a sleeve made of a material of high toughness is hot drawn onto a core consisting of heavy metals, heavy metal alloys or heavy metal sintering materials and then the sleeve is cooled. The sleeve is made of pure conversion-free pure iron or high-strength tempered steel.

The invention has for its object to provide a comparison with other known methods simpler method for producing a penetrator with brittle penetrating core and ductile jacket.

This object is achieved by the features of claim 1. Further, particularly advantageous embodiments of the invention disclose the dependent claims.

The invention is based on the idea of concentrically introducing in a mold adapted to the outer dimensions of the penetrator, a double hopper filling device adapted to the dimensions of the penetrator core. While in the inner tube, a first tungsten-containing powder mixture with high tungsten content (90-99 wt.%) Is filled to produce the penetrator core, in the annular space located between the outer wall of the inner tube and the inner wall of the mold, a second tungsten-containing powder mixture with respect to the first Powder mixture lower tungsten content (approximately between 83% and 91%) introduced. After removal of the inner tube from the mold then carried out in a conventional manner required for the preparation of the penetrator pressing the powder mixture, the sintering, the cold forming of the compact and finally the finishing of the Penetratorrohlings.

By means of the method according to the invention, a penetrator is produced with a core of high density and a tough outer sheath frictionally connected to the penetrator core, wherein the outer jacket prevents breakage on oblique target impact. The production of a separate shell and a complicated attachment of such a shell to the penetrator core, as in the case of the aforementioned DE 40 16 051 C2 , can be omitted.

In an advantageous embodiment of the invention, a mixture with 95% by weight of tungsten and a balance of nickel and cobalt powder in a weight ratio of 9: 1 has proven to be the first tungsten-containing powder mixture.

In a further embodiment of the invention, a mixture of 87% by weight of tungsten and a balance of nickel and cobalt powder, likewise in a weight ratio of 9: 1, was obtained as the second tungsten-containing powder mixture in an advantageous manner.

Further details and advantages of the invention will become apparent from the dependent claims.

The invention will be explained in more detail with reference to an embodiment with drawing.

Fig.1

einen Längsschnitt durch eine Form zur Herstellung eines Penetratorrohlings mit darin enthaltenen Pulvermischungen und

Fig.2

einen Längsschnitt eines Teiles des nach dem erfindungsgemäßen Verfahren hergestellten Penetrators.

In Fig.1 ist mit 1 eine an die Außenabmessungen des herzustellenden Presslings angepasste Pressform aus Kunststoff bezeichnet, in der konzentrisch eine Doppeltrichtereinfüllvorrichtung eingebracht ist. Das Innenrohr 3 und die Doppeltrichter 2 sind vorzugsweise aus Edelstahl und weisen eine Wandstärke von ca. 1 mm auf. Der zwischen der Pressform 1 und dem Innenrohr 3 befindliche ringförmige Raum besitzt einen Wandabstand von etwa 1/8 des Innendurchmessers. Beide konzentrischen Trichter sind im konischen Bereich mit Hilfe von Querstreben verbunden.Show it:

Fig.1

a longitudinal section through a mold for producing a Penetratorrohlings with powder mixtures contained therein and

Fig.2

a longitudinal section of a portion of the penetrator prepared by the process according to the invention.

In Fig.1 is designated by 1 adapted to the outer dimensions of the compact to be produced mold made of plastic, in which a Doppeltrichtereinfüllvorrichtung is introduced concentrically. The inner tube 3 and the double funnel 2 are preferably made of stainless steel and have a wall thickness of about 1 mm. The annular space located between the die 1 and the inner tube 3 has a wall distance of about 1/8 of the inner diameter. Both concentric funnels are connected in the conical area by means of transverse struts.

Into the inner tube 3, a first tungsten-containing powder mixture 4 is introduced with a tungsten content of 95 wt .-% and a balance of nickel and cobalt powder in a weight ratio of 9: 1. Subsequently, a second tungsten-containing powder mixture 5 having a tungsten content of 87% by weight and likewise a balance of nickel and cobalt powder in a weight ratio of 9: 1 is introduced into the annular space.

After the introduction of the powder mixtures 4 and 5, the Doppeltrichtereinfüllvorrichtung is removed from the press matrix 1 and then hydrostatically compressed the entire powder mixture after a for example caused by shaking pre-compression. Then the compact is then finished according to the desired specifications Penetrators sintered in a conventional manner, heat-treated, cold-formed, hot outsourced and then finished by a machining process, such as from US 3,979,234 known.

Fig.2 shows the longitudinal section of a portion of the penetrator 10 produced by the process according to the invention. Here, denoted by 6 of the relatively high due to the high proportion of tungsten penetrant core and with 7 due to the lower tungsten content significantly more ductile outer sheath with thread.

Between the penetrator core 6 and the outer jacket 7, there results a transition region 8 with a preferred thickness of between 25 μm and 200 μm, which ensures good adhesion between the core 6 and the jacket 7. The tough shell 7 is preferably removed in the tip-side region, for example by machining, so that it is made of a core material tip and breaks brittle in the target impact, whereby ever-sharp Anbeißkanten arise that ensure a good Anbeißverhalten.

LIST OF REFERENCE NUMBERS

1

Pressmatrix (plastic)

2

Double funnel (stainless steel)

3

Inner tube (stainless steel)

4

Core powder mixture

5

Rand powder mixture

6

brittle penetrator core

7

ductile penetrator jacket (with thread)

8th

Transition area core coat

10

penetrator

Claims (4)

1. Method for producing a penetrator (10) made of tungsten heavy metal with a high tungsten fraction and having an outer sheath (7) which consists of a material which is more ductile compared to the penetrator core (6), wherein

   a) a thin-walled inner pipe (3) of a double funnel filling device, which inner pipe is adapted to the dimensions of the penetrator core (6), is concentrically inserted into a compression matrix (1) adapted to the exterior dimensions of the penetrator (10), and is filled with a first tungsten-containing powder mixture (4) with a tungsten fraction of between 90% by weight and 97% by weight;

   b) the annular space located between the outer wall of the inner pipe (3) and the inner wall of the compression matrix (1) is filled with a second tungsten-containing powder mixture (5), the tungsten fraction of which is between 85% by weight and 91% by weight;

   c) subsequently, the double funnel filling device is removed from the compression matrix (1), and

   d) the powder mixture is pressed and sintered, the pressed body is subjected to cold forming and the penetrator blank is then finished.
2. Method according to Claim 1, characterized in that the first tungsten-containing powder mixture (4) contains 95% by weight tungsten, and the remainder of the powder mixture consists of nickel powder and cobalt powder.
3. Method according to Claim 1 or 2, characterized in that the second tungsten-containing powder mixture (5) contains 87% by weight tungsten, and the remainder of the powder mixture consists of nickel powder and cobalt powder.
4. Method according to Claim 2 or 3, characterized in that the nickel powder and cobalt powder in the first and/or second tungsten-containing powder mixture (4, 5) have a weight ratio of between 2:1 and 10:1, preferably of 9:1.

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