GB2244119A

GB2244119A - Jacketed penetrators

Info

Publication number: GB2244119A
Application number: GB9106120A
Authority: GB
Inventors: Gert Kueppers; Rene Oudelhoven
Original assignee: Rheinmetall GmbH
Current assignee: Rheinmetall Industrie AG
Priority date: 1990-05-18
Filing date: 1991-03-22
Publication date: 1991-11-20
Anticipated expiration: 2011-03-22
Also published as: GB9106120D0; DE4016051C2; GB2244119B; DE4016051A1

Abstract

A jacketed penetrator (10) has a rupturable penetrator core (11) and a stool jacket (20) applied thereto forming a ductile casing. The jacket is formed by a pressure rolling method which avoids the requirement of a prefabricated jacket being frictionally connected or positively interlocked with the penetrator. This arrangement provides an economical means for mass production and enables a complete projectile to be manufactured which comprises a penetrator (11), a tail unit (25) and a casing with integral nose (24). <IMAGE>

Description

2 1 -1 - 1. 1 1:D 1 - 1 TITLE Jacketed Penetrators The invention relates

to a jacketed penetrator.

A projectile system is known from DE 2234219/Cl in which a prefabricated tubular steel jacket is connected to a rupturable tungsten carbide penetrator core by means of a screw threading extending over the entire periphery of the penetrator core and inside a steel tube forming a jacket. Alternatively a welded connection can be provided to achieve a positive interlock or frictional connection therewith. Although the energy beam welding used provides a strong punctiform connection it does not provide a usable connection between the actual surfaces of the two components which is desirable for the necessary resistance of the projectile to the stresses accompanying the firing. As regards the interconnection produced with screw threading the costly processing involved and the application of an external threading to the brittle penetrator core constitutes a drawback, as it renders it far more liable to break.

The method disclosed in DE 33 39 078/Al for securing a easing by means of. a hard soldering connection likewise suffers from the drawback that the mechanical strength of 0 the penetrator material is reduced by the uncontrolled effect of heat. Soldered connections are also very difficult to produce owing to the very large surface to be soldered.

A projectile is also described in unpublished application DE P 3911575.5, in which a steel jacket is applied to the penetrator by a build-up welding process. It has been found, however, that in special cases the build-up welding operation applied for securing the steel easing may adversely effect the mechanical properties and structure of the penetrator material owing to the development of undesirable heat. In addition this process is very expensive and unsuitable for series production.

An object of this invention is to protect a rupturable penetrator with a ductile jacket secured to the penetrator core in a manner which provides resistance to the firing stresses and which obviates the disadvantages of known methods of securing, thus enabling a jacketed penetrator to be economically mass produced.

According to this invention there is provided a jacketed penetrator comprising a penetrator element having a high density and embraced by a jacket, the jacket having been applied to the penetrator element by a pressure rolling process to form a ductile but firm 3 easing at least partly enclosing the said penetrator.

This invention is further described in conjunction with the drawings showing several preferred embodiments. In the drawings:- Figure 1 shows a sub-calibre penetrator projectile with a steel jacket applied by a pressure rolling process, Figures 2, 3 and 4 show further examples of an applied steel jacket, and Figure 5 shows a completely encased projectile.

In the drawings 10 generally indicates a subcalibre penetrator projectile with a penetrator 11 and a surrounding jacket 20. The penetrator 11 has a tail 13 of which the diameter is smaller than the mean diameter of the penetrator and which serves to secure a tail assembly (not shown). The penetrator 11 tapers conically in a direction towards the tail 13 and in the example of Figure 1 is embraced over part of the length by the jacket 20 which has been applied as a ductile and sufficiently resistant jacket to the surface of the penetrator by a pressure rolling process.

The surface of the penetrator 11 and/or the jacket to be applied has been given a preselected degree of surface roughness in order to ensure adequate force transmission between the jacket 20 and the penetrator 11.

In this connection it has been found to be of particular advantage to give the penetrator 11 a slight conical taper in or opposite to the direction of flight to achieve this force transmission and to apply the jacket 20 in such a way that it will be thicker in the zones where the diameter is reduced, in order to produce a uniform external diameter which can be used to accommodate a sabot (not shown).

The jacket 20 applied to the penetrator by the pressure rolling method serves to protect a penetrator 11 which is made of a dense brittle tungsten material. Modern kinetic energy projectiles, particularly those with a high ratio of length to diameter, are subject to high stresses due to oscillations occurring during the firing operation and in the course of flight. They also suffer from flexure accompanying passage through oblique, structured or active targets.

The pressure rolling process applied in accordance with this invention can also be used to provide a cylindrical penetrator surface with the ductile jacket concerned. In this case the said penetrator surface can be provided with slight rounded notches to ensure better force transmission between the penetrator 11 and the jacket 20.

The basic condition of the pressure rolling process (flow forming) is that the radial force of the pressure rollers suffices to cause the material of the blank to flow over the entire cross section of the wall thickness towards a mandrel. Pressure rolling is thus a compressive forming process in which the workpiece to be deformed only suffers a limited ductility loss during the conversion process. This enables the wall thicknesses of the material of the blank to be reduced by up to 90%, so that steels and other metal alloys can be cold-formed even in the tempered or solution heated state. The method can be applied to cylindrical and also to conical, concave and convex workpiece shapes.

In pressure rolling with a cylindrical mandrel a distinction can be drawn between synchronised and reverse pressure rolling. In synchronised pressure rolling used in accordance with the present invention the contact points of the individual pressure rollers, of which there are preferably two staggered in relation to each other by an angle of 180o, take a helical course along the generating line of the pressure mandrel. The pressure mandrel for the purposes of the present invention is a penetrator to be provided with a jacket and rotating about the longitudinal axis. The direction of rotation of the pressure rollers are opposite to that of the main spindle of the machine to which the penetrator is secured. In the processing the flow of the material - that to be applied to the jacket takes the same axial 1 direction as the feed movement of the pressure rollers.

The synchronised pressure rolling method offers the advantage of also enabling non-cylindrical workpiece shapes to be produced and of attaining high conversion speeds.

As shown in Figure 2, the pressure rolling process also enables a multilayer jacket 20, 21 to be applied. For this purpose materials such as steel, copper, nickel, titanium or tantalum can be employed in different combinations and thicknesses for the production of jackets comprising a number of layers (20,21).

Figure 3 shows that the application of a jacket 20 by the pressure rolling process does not have to extend the entire length of the penetrator 11 and can equally well be confined to certain zones thereof. Figure 3 shows a penetrator 11 of which two separate sections are surrounded by their respective steel jackets 22, 23. Such separate jackets 22,23 can likewise be of the multilayer type.

In Figure 4 the penetrator 11 comprises a number of individual parts 14, 15, 16 which may consist of different materials. By using the pressure rolling process these individual parts 14, 15, 16 can be :4 r 7 advantageously combined to form a compact unit by the application of a jacket 20. In the drawing the said jacket 20 extends over the entire length of the penetrator 11 thus forming a projectile 10 having a nose 24 shaped in the form of a ballistic nose which can be pressure rolled from steel. The tail 13 of the penetrator in this diagram is not encased and serves, as in the examples shown in Figure 1, 2 or 3, to secure a tail unit (not shown).

A particular advantageous use of the pressure rolling process for the application of a ductile jacket is illustrated in Figure 5. This method provides, in successive operations, a means of producing a complete projectile 10 consisting of a penetrator 11, a tail unit 25 and a jacket with an integral nose 24. In Figure 5, as in Figure 4, the jacket 21 takes the form of a rolledout ballistic nose. A tail unit 25 is provided on the tail 13 of the penetrator. This tail unit 25 has a prefabricated part taking the form desired, for example a finned tail unit, which is not screwed, stuck or soldered onto the penetrator tail 13, as in the case of conventional projectiles, but is affixed to the penetrator 11 in the same way as the jacket using the pressure rolling process. For this purpose the tail unit 25 has a cylindrical part 28 provided with an - 8 internal boring serving to receive the penetrator tail 13. This cylindrical part 28 is pressure-rolled into a shape ensuring frictional connection or positive interlock with the penetrator 11. This provides the advantage of dispensing with the screw threading having to be cut on the tail unit 25 and the penetrator 11 and also with any additional adhesive connection.

The force transmission geometry taking the form of notches 26 or grooves 27 is provided on the outside of the jacket 20 itself in a further operation such as the provision of screw threading by a cutting, rolling or knurling method.

In Figure 5 the penetrator 11 is also slightly conical. The thickness of the jacket 20 evens out the diameter of the penetrator surface in such a way that the central portion of the encased projectile 10 has a uniform external diameter.

For force transmission the geometry shown in Figure 5 serves to secure a sabot (not shown) and takes the form of notches 26 or grooves 27, which can also be provided on the jacket 20 for the arrangements shown in Figures 1 to 4 and are thus also feasible for one single jacket 20 surrounding only one portion of the penetrator 11 (as shown in Figure 1) or on a jacket 20,21, consisting of more than one layer (as seen in Figure 2).

1 i 1 311 With the pressure rolling process applied in accordance with the present invention a penetrator 11 can be provided with a ductile jacket in order to prevent it from breaking as a result of vibrations and flexural stress. The process for the application of the jacket to the material from which the penetrators are made and which by its nature is already brittle exerts no adverse effect on it in the operations required and the mechanical properties of the jacket 20 can be 1 advantageously selected by means of an additional thermal treatment without harming the said penetrator material.

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Claims

1. A jacketed penetrator comprising a penetrator element having a high density and embraced by a jacket, the jacket having been applied to the penetrator element by a pressure rolling process to form a ductile but firm easing at least partly enclosing the said penetrator.

2. A jacketed penetrator in accordance with Claim 1, wherein the pressure rolling process is used to fabricate a complete projectile which comprises a penetrator, a tail unit and a jacket with a nose formed thereon.

3. A jacketed penetrator in accordance with Claim 1 or 2, wherein the penetrator is of conical shape.

4. A jacketed penetrator in accordance with any preceding claim, wherein the jacket is applied in a number of layers of different materials.

5. A jacketed penetrator in accordance with any preceding claim, wherein the penetrator comprises a number of separate parts each of a different material which parts are combined to form an element by means of the jacket applied thereto.

1 11 -

6. A jacketed penetrator in accordance with any preceding claim wherein the jacket is provided externally with a frictional or interlocking connection zone.

7. A jacketed penetrator in accordance with any preceding claim wherein the jacket comprises steel.

8. A jacketed penetrator substantially as described herein and exemplified with reference to the drawings.

Published 1991 atIbe Patent Office, Concept House, Cardiff Road, Newport, Gwent NP9 1RH. Further copies may be obtained from Sales Branch. Unit 6, Nine Mile Point, Cwmfelinfach, Cross Keys. Newport, NP I 7HZ. Printed by Multiplex techniques lid, St Mary C-ray, Kent.