GB2227298A

GB2227298A - Hollow charge

Info

Publication number: GB2227298A
Application number: GB8421698A
Authority: GB
Inventors: Klaus Weimann
Original assignee: Fraunhofer Gesellschaft zur Forderung der Angewandten Forschung eV
Current assignee: Fraunhofer Gesellschaft zur Forderung der Angewandten Forschung eV
Priority date: 1984-08-28
Filing date: 1984-08-28
Publication date: 1990-07-25
Anticipated expiration: 2004-08-28
Also published as: GB2227298B

Abstract

A device for producing explosive shaped projectiles comprises a case 1, Fig 1, with an explosive charge 3, detonating means situated 10 at its bottom end and a metal insert 4 covering the explosive charge at its top end, the projectile, Fig 6, acquiring at its rear fin-like symmetrical folds 7 because the outer part of the insert and/or of the explosive charge and/or of the detonating means and/or the envelope of the case has at least three inhomogeneities disposed symmetrically on a circle at a distance from the axis of the case in such a way that in the peripheral zone of the insert differential acceleration occurs or the impact time or impact energy of the shock wave differs in accordance with the arrangement of the inhomogeneities. <IMAGE>

Description

A device for producing explosively shaped projectiles The invention relates to a device for producing explosively shaped projectiles, comprising a case with an explosive charge, detonating means situated at its bottom end and a metal insert covering the explosive charge at its top end.

9 very simple form of device of the type described is also termed a hollow charge. A hollou charge of this kind comprises the parts mentioned, the case being cylindrical, and it functions in such a way that on ignition of the explosive the insert is broKen down into individual narticles w@ich then acvance on the target like a projectile. Wit@ @@@h @ollo@ ctarges all efforts are concentratec on pros@cing carticles @f @aterial which @it the target with as muc@ energy as possiole. In practice this is achie@@@ (f@r example as ce@cri@@c in @@-AS 19 le 779) py snating t@e insert so t@at it is broken doun into a plurality of small particles, knoun as the "jet", and one or more large particles (the "ram").

Such an insert may, for example, be comec. it is said that a smaller number of larder, elongated particles may be produced if the domed disc has a concentric predetermined fracture point.

The desirability of elongated projectiles of large mass, uhich thus combine good flight prooerties with high impact energy, led to the idea of forming the insert from a composite material, so that, for example, it consists at the centre of a relatively heavy metal, mostly of steel and at the edges of aluminium. If the explosive charge is suitably arranged, such an insert can be converted into a single elongated projectile of uhich the external shape is similar to a shell, uith a rounded nose and an adjoining cylindrical or slightly conical elongated portion. The rear of this projectile is formed into a kind of disc.

Such a projectile flies accurately to its target, but does not exhibit high impact energy, since its disc-like rear increases its air resistance and the projectile therefore loses considerable speed in flight.

4n object of the invention is to design a device of the type initially described in sucn a uay as to produce explosively generated projectiles tJitn satisfactory and reproducible flight @roperties, which attain their target uith ootimum alignment and a s-all loss of speed.

To this end, according to t@e invention, the outer part of the insert and/or of tr explosive charge and/or of the detonating means ano/or te envelope pr tne case has at least three in@omogeneities cisposec $@@@etrically on a circle at a distance from the axis of the case in such a way that in tne peripheral zone of tne insert differential acceleration occurs or the impact tine or impact energy of the shock uave differs in accordance ijith the arrangement of the inhomogeneities.

The invention derives from recognition of the fact that the explosively generated projectile does not have satisfactory flight properties unless care is taken to ensure that the insert is deformed along preset preferential directions, which lead to staggered deformation, so always ensuring that neighbouring portions of the insert are deformed not simultaneously, but successively or at different rates. If this rule is observed it can be assumed that deformation will not produce uncontrolled accumulations, compression or overlaps of material which would cause fraying of the rear of the projectile.

Froceeding from this idea, the general principle of the solution in accordance with the invention is that the parts forming the device, alone or in combination, comprise in defined places near the periphery inhomogeneities which cause the shock wave generated oy the explosive charge to take effect on different arrange-ents of mass in the insert or not to affect tne entire insert 3t the same time or with the same impact energy, bot to -se affect on definite and symmetrically rrane points near te periphery of the insert at ciffere-t ti-es or wit different impact energy.This ensures that the parts on which the shock wave acts earlier or with higher Impact energy are deformed first and the other parts later. If the inhomogeneity comprises a different arrangement of mass, the areas of lower mass are deformed at a faster rate than the areas between them. This solution can be embodied by corresponding, symnetrically arranged inhomogeneities in the insert itself, in the explosive charge, in the detonating means or in the case.

Inhomogeneities in the insert lead primarily to different rates of deformation of the insert. Inhomogeneities in the explosive charge produce different impact energies at the insert. Inhomogeneities in the detonating means do the same, but may also produce different impact times.

Lastly, inhomogeneities in the case lead to differential stemming on detonation and thus again to differential impact energies at the insert.

In a preferred embodiment, the insert comprises as inhomogeneities substantially rcial eforn-ations in tWe peripheral zone, which may for example be in the Form of shalow corrogations. This profili@@ is @referably of the order of C.l mm. @lter@atively, or edditi@@elly, the deformations may @e in the for@ of co@@entrations of material.

According to a further feature, which may be provided in addition to the deformations if desired, the insert comprises in the peripheral zone suostantially radial portions of different wall thickness. Trese differences in wall thickness, also, are preferably of the order of 0.1 mm. In these cases, therefore, the insert is provided with substantially radial inhomogeneities which cause it to deform in a definite and symmetrical manner under the impact of the shock wave. Practical experiments have demonstrated that it is possible in this way to obtain projectiles with a rounded nose, a longer, substantially cylindrical portion and, at the rear, uniform longitudinal folds, the number of folds equalling the number of inhomogeneities present. The depth and shape of the folds depend largely on the extent of the inhomogeneities.In flight the folds act as stabiliser fins. Practical tests have demonstrated exceptional flight qualities, the longitudinal axis of the projectile being aligned along the flight path and remaining in this position. The inevitable slight inclination on firing of the projectile stabilises after a few low-amplitude swings, so that oractically every projectile hits its target in the desired flight position.

Another result of the fins is a substantially smaller loss of speed, so that the impact energy available is correspondingly higher.

An equally advantageous effect can be obtained, according to another embodiment, if the explosive charge comprises inhomogeneities in the form of a differential arrangement of explosive disposed symmetrically in the peripheral zone. This symmetrically differential arrangement can be obtained by means of explosives of different kinds or the same explosives in different concentrations. This leads to different times and/or energies of impact at the insert, so that, again, the insert is deformed first in preferred directions and then elsewhere.

According to another embodiment, the same effect can be obtained if the explosive charge comprises inhomogeneities in the form of guides arranged symmetrically in the case, the guides diverting the shock wave onto definite parts of the insert in a correspondingly symmetrical manner and/or additionally stemming the shock wave at correspondingly symmetrical points.

According to another possible solution, the detonating means comprises ignition points of lower ignition energy and/or delayed time of ignition arranged symmetrically in the peripheral zone. This in turn causes the shock wave to hit the corresponding symmetrically arranged points on the insert at different times, depending on the arrangement of ignition points or their delays.

According to a further embodiment, the case may comprise inhomogeneities in the form of symmetrically arranged variations in wall thickness. This varying wall thickness causes differential lateral stemming or confinement of the explosive and hence different firing speeds for the charge. The charge is slower at points of low wall thickness than at the more strongly confined points in the case. Since this differential stemming or confinement takes effect primarily in the peripheral zone, this feature too acts only in the peripheral zone of the insert, just as desired. In an embodiment which is particularly easy to produce, the case is in the form of a circular cylinder internally and a prism externally.

According to a further development of the idea underlying the invention, the inhomogeneities differ from one another in depth, but within at least each pair of inhomogeneities they are of equal depth and are symmetrically arranged.

This further development of the invention has the result that the folds forming at the rear of the projectile are of different depths, and therefore form fis of different widths. The symmetrical arrancernent in groups of at least two diffarent inhamogeneities, however, ensures that fin formation is symmetrical elative o to -a axis of the projectile.

Lastly, according to a further @eature of the invention, the inhomogeneities may be asy@metrical in themselves, but all exhibit the identical asymmetry. This arrangement acaln ensures preferential cirections within each inhomogeneity, with the result that the defor-ation of the insert occurs not absolutely simultaneously in the vicinity of every inhomogeneity, but at slihtly different times or with slightly different impact energy or at a different rate. The folds at the rear of the resulting explosively generated projectile then run not parallel to the axis of the projectile, but at an inclination to it.

Inclined fins, as produced by the folds in this case, may also give the projectile a stabilising spin.

The invention will now be described by way of example with reference to a number of embodiments. In the drawings: Figure 1 represents a diagrammatic longitudinal section through the device; Figure 2 is a side view of one embodiment of the insert; Figure 3 is a plan of the insert shown in Figure 2; Figure 4 shows a section through a first embodiment of the case; Figure 5 is a section through the device, illustrating two further embodiments; Figure 5 is a side view of an embodiment of explosively generated projectile; and Figure 7 is an end view of the rear of the projectile shown in Figure 6.

The device illustrated in Figure 1 comprises a case 1 which has a bottom 2 filled with explosive 3 and closed at the top with an insert 4. Detonating means 10 is placed in the vicinity of the bottom 2. The case 1 is cylindrical, and the insert 4 is in the form of a thin dished disc.

It is made of metal, for example, steel, copper or heavy metal.

In the embodiment illustrated in Figure 2 the insert 4 is provided with inhomogeneities 5 which take the form of wave-like deformations 6 in the disc. These deformations or corrugations extend substantially radially (Figure 3), from a point spaced radially from the disc centre to the periphery of the disc. The corrugations therefore increase in height towards the exterior. The inhomogeneity may be made more marked by, for example, reducing the wall thickness in the vicinity of the humps in the corrugations, as is easily done by grinding over the disc 4 on the side bearing the humps 6, so giving a grinding pattern substantially as shown in Figure 3.

0n ignition of the explosive charge 3 a domed shock wave forms, whicn first hits the centre of the disc 4, so that deformation begins there. There is aslight delay before the shock wave hits all the areas fort out, so tat at first the disc bulges outwards at tre centre. In the disc's peripheral zone, because oF the in homogeneities 5, t:The smock wave first hits the areas between the humps 6 of the corrugations, so that the deformation process begins there, whereas the areas 6 receive the impact later and undergo delayed deformation.

This ultimately produces a projectile as shown in Figures 6 and 7. It comprises a portion A, which has been created from the central part of the disc 4 and gives the projectile a rounded nose, and an elongated, substantially cylindrical portion a. The portions A and B are solid. Lastly, the portion C exhibits separate, equispaced folds 7 which act as stabiliser fins for the projectile. As the end view of the rear of the projectile in Figure 7 shows, the fins are symmetrically arranged and are themselves symmetrical in form.

Instead of the inhomogeneities 5 in the insert 4, or in addition to them, the detonating means 10 may comprise inhomogeneities, a plurality of ignition points 8, 9 of differing ignition energy or differing ignition delay being arranged in a suitably symmetrical fashion at the bottom end of the case 1.

Figure 4 shows another embodiment which is notably simple to produce. In this case the interior of the case is a cylinder 11, while its exterior is a prism (a regular hexahedron in the embodiment illustrated).

This leads to a greater wall thickness in the areas 12 and to a minimum wall thickness in the areas 13. because of this variation in wall thickness the stemming action is greatest in the areas 12 and least in the areas 13. In the projection of the areas 12, accordingly, more energy is transmitted to the insert , and the latter is accelerated there to a greater extent, whereas in the projection of the areas 13 the insert lags behind in the deformation process.

Figure 5 illustrates a combination of the embodiment shown in Figure 4 (but in this case an octahedron) with a symmetrically variable arrangement of explosive. whereas most of the case 1 is filled with explosive 14 of a given energy, the parts near the corners of the prism contain a different explosive 15, which is for example of higher energy or energy density and so adds to the effect of the greater stemming action in those areas. In a completely cylindrical case 1 too, of course, a symmetrically disposed differential explosive arrangement my be provided.

Lastly, Figure 5 also illustrates an embodiment in which the inhomogeneities are asymmetrical in themselves.

As indicated on the outer surface lo of the case 1, the case may contain asymmetrical depressions formed by inclined surfaces 17, 13. Sy means of this asymmetry, which however is the same in all the inhomogeneities, the folds 7 (Figures 6, 7) of the projectile can be made to incline relative to tne axis of the projectile, so imparting spin to the projectile in flight.

Claims

1. A device for producing explosively shaped projectiles, comprising a case with an explosive charge, detonating means situated at its bottom end and a metal insert covering the explosive charge at its top end, characterised in that the outer part of the insert (4) and/or of the explosive charge (3) and/or of the detonating means (10) and/or the envelope of the case (1) has at least three inhomogeneities (5) disposed symmetrically on a circle at a distance from the axis of the case in such a way that in the peripheral zone of the insert (4) differential acceleration occurs or the impact time or impact energy of the shock wave differs in accordance wit the arrangement of the inhomogeneities.

2. c device as claimed in claln 1, characterised in that the insert (4) comprises as inhomogeneities (5) substantially radial deformations (; in tne Derioneral zone.

3. A device as claImed in @ aim 1 or 2, cnacacterised in that the deformations (6) are in tne form of shallow corrugations.

4. a device as claimed in claim 1 or 2, characterised in that the deformations are in the form of concentrations of material.

5. 4 device as claimed in any of claims 1 to 4, characterised in that tne insert (4! comprises in the peripheral zone substantially racial portions of different wall thickness.

6. A device as claimed in any of claims 1 to 5, characterised in that the explosive charge (3) comprises inhomogeneities (5) in the form of a differential arrangement (15) of explosive disposed symmetrically in the peripheral zone.

7. A device as claimed in any of claims 1 to 5, characterised in that the explosive charge (3) comprises inhomogeneities in the form of guides arranged symmetrically in the case (1).

8. A device as claimed in any of claims 1 to 7, characterised in that the detonating means (10) comprises ignition joints (a, 9) of tower ignition energy and/or delayed time of ignition arranges symmetrically in the peripheral zone.

9. A device as claimea in any of claims 1 to a, characterised in that the case (1) comprises inhomogeneities in the form of symmetrically arrangec variations (12, 13) in wall thickness.

10. P device as claimed in claim 9, characterised in that the case (1) is in the form of a circular cylinder internally (ll) and a prism externally.

11. A device as claimed in any of claims 1 to 10, characterised in that the inhomogeneities (5) differ from one another in depth, but within at least each pair of inhomogeneities they are of equal depth and are symmetrically arranged.

12. A device as claimed in any of claims 1 to 11, characterised in that the inhomogeneities (5) are individually asymmetrical, but all exhibit the same asymmetry (17, 18).

12. 9 device as claimed in any of claims 1 to 11, characterised in that the inhomogeneities (5) are individually asymmetrical, but all exhibit the same asymmetry (17, 18).

Amendments to the claims have been filed as follows 1. A device for producing explosively shaped projectiles, comprising a case with an explosive charge, detonating means situated at its bottom end and a metal insert covering the explosive charge at its top end, the whole having anaxis of symmetry characterised in that: the outer part of the insert (4) and/or of the explosive charge (3) and/or of the detonating means (10) and/or the envelope of the case (1) has at least three inhomogeneities as herein defined (S) disposed symmetrically about a circle at a distance from the axis of the case in such a way that in the peripheral zone of the insert (4) differential acceleration occurs or the impact time or impact energy of the shock wave differs in accordance with the arrangement of the inhomogeneities.

2. A device as claimed in claiml. characterised in that the insert (4) comprises as inhomogeneities (5) substantially radial deformation (6) in the periphral zone.

3. A device as claimed in claim 1 or 2, characterised in that the deformation (6) are in the form of shallow corrugations.

5. A device as claimed in any of claims 1 to 4.

characterised in that the insert (4) comprises in the peripheral zone substantially radial portions of different wall thickness.

B. A device as claimed in any of claims 1 to 7, characterised in that the detonating means (10) comprises ignition points (8, 9) of lower ignition energy and/or delayed time of ignition arranged symmetrically in the peripheral zone.

9. A device as claimed in any of claims 1 to 8, characterised in that the case (1) comprises inhomogeneities in the form of symmetrically arranged variations (12, 13) in wall thickness.

10. A device as claimed in claim 9, characterised in that the case (1) is in the form of a circular cylinder internally (11) and a prism externally.