GB2332037A

GB2332037A - A projectile-forming insert for a hollow charge

Info

Publication number: GB2332037A
Application number: GB8900700A
Authority: GB
Inventors: Klaus Lindstadt
Original assignee: Diehl GmbH and Co
Current assignee: Diehl Verwaltungs Stiftung
Priority date: 1988-03-11
Filing date: 1989-01-12
Publication date: 1999-06-09
Anticipated expiration: 2009-01-12
Also published as: FR2775069A1; GB8900700D0; GB2332037A9; FR2775069B1; GB2332037B; DE3808052C1

Abstract

A rotationally-symmetrical projectile-forming hollow-charge insert (12) more especially for armour-piercing seeker-fuze submunition, has a central dome (24) of substantially constant material thickness (26) is surrounded by an peripheral region (25) having a material thickness decreasing somewhat towards the periphery (19). An intermediate portion decreases in thickness from a maximum adjacent the dome (24) to a minimum adjoining the peripheral portion (25). The insert is transformed into a projectile having a stub-wing tail (22) which protrudes in a radially-annular manner at the end of the projectile (11) and which is thereby flight-stabilising.

Description

1 A PROJECTILE-FORMING INSERT 2332037 The invention relates to an insert

in accordance with the definition of the species of claim 1.

Such an insert is known from US-PS 4 590 861; the preferred munitiontechnology use of a projectile-forming insert in seeker-fuze munition is described, for instance, in US-PS 4 587 902. The hollow-spherical-capshaped inserthas, in the circumferential direction, a succession of regions of different materiall thicknesses, in order to achieve, upon the folding transformation of the insert into the projectile, in the circumferential direction different material compaction zones and thereby of flight-stabilising stub wings on projectile tail. This solution has proved to be very functional; the production expenditure for a, in the interests of symmetrical projectile formation exactly rotationally symmetrical succeeding one another in of different formation the the 0 distribution of the zones, the circumferential direction, material thicknesses is, however, disadvantageous. Above all, however, it is functionally disadvantageous that, upon changing to material of greater density such as copper or even tantalum, the transformation of the spherical cap does not result in a flight-stable projectile, but a quasi-cylindrical or shallow-frustoconical structure, having an aerodynamically effective centre of pressure lying in front of or close to its centre of gravity. The in itself more favourable 2 higher mass of the projectile thus cannot sufficiently take effect in the target, because the projectile does not fly in a directionally stable manner and therefore does not hit the target or at any rate does not do so axially.

In recognition of these factors the problem underlying the invention is to indicate a rotationally symmetrical insert for transformation into a projectile of high effect even in the hard-armoured target object, the production expenditure of which - more especially also considering insert metals which are difficult to work - is reduced and which more especially produces a transformation into a flight-stable projectile.

This problem is solved in accordance with the invention essentially in that the insert of the type in accordance with the species is developed in accordance with the characterising part of claim 1 and/or of claim 10.

The solution is based on the consideration that the described productiontechnology expenditure for the insert, to achieve a stub-wing tail which is start-shaped in cross-section on the projectile, is not required if only it is ensured that the insert, upon the explosive transformation, is not ruptured and also is not transformed into a flight-unstable cylindrical structure, but into a compact and unif ormly- stretched projectile 1 3 having a tail which distinctly protrudes radially beyond the nose diameter, thus a f light- stabilising tail. This is achieved in production-technology respects in an unproblematical manner if a start is made from a round, thus a round plate having plane-parallel surfaces, which, with progressive narrowing of the material thickness of its edge region towards the periphery, is arched out as a very shallow cap and is equipped at the periphery with an edge region which encircles in a collarshaped manner.

By virtue of the simply configurated starting material and of the (in comparison with obtuse-angled hollow-cone inserts or hollow spherical caps) only relatively slight buckling deformation of the centre of the blank now materials can also be used without problems for the insert which, by reason of their height density and their good stretching properties, would in themselves be favourable for the projectile formation, but for production- technology reasons to date were scarcely able to be taken into account for an industrial production of inserts. Such a material is in particular tantalum, which has good stretching properties. The mass reduction of the only slightly narrowed edge region, encircling along the periphery, of the insert in accordance with the present invention increases the edge-region acceleration of the radial motion component upon the folding procedure and thereby leads, behind the rapidly preceding mass of the shal lowly- arched insert centre, to the compact projectile 1 4 body, well symmetrical about the longitudinal axis, having an edge which remains protruding annularly on the tail of the projectile at the end of the transf orming- stretching procedure and which stems from the periphery of the 5 insert.

These kinematic transforming factors are further promoted if, in accordance with an advantageous further development of the invention, the thinned edge region of the insert is inclined forwardly out of the transverse plane thereof somewhat towards the insert support, thus in the effective direction, in order thereby to impart an additional radial acceleration to the periphery upon the folding procedure. If this support experiences a forwardly somewhat narrowing framing, then the edge region of the plate- shaped insert can yield more easily towards the centre under the action of the rearward explosive charge. In this way material burst-off phenomena at the developing tail, thus asymmetries and tilting moments which would be detrimental to the stable flight properties, are avoided.

Additional alternatives and further developments as well as further features and advantages of the invention will become apparent from the further claims and, also taking into account what is set forth in the abstract, from the following description of a preferred example of a realisation with regard to the solution in accordance with i 1 the invention which is shown in the drawings along with a restriction to that which is essential in a highly enlarged manner and not entirely trueto-scale.

Fig. 1 shows a flight-dynamically poorly designed projectile in comparison with a well designed projectile obtained from explosive transformation of an insert, in side view, Fig. 2 shows design and mounting support of a shallowlycap-shaped or plate-shaped insert, after insertion into the front region of an explosive-filled casing, in brokenaway axial longitudinal sectional representation, Fig. 3 shows the insert prior to its arching in brokenaway longitudinal sectional representation, and Fig. 4 shows a die for the pressing of the round in accordance with Fig. 3 for the arching into the insert in accordance with Fig. 2.

An explosive- shaped projectile 11 obtained from an insert 12 (Fig. 2) concentrically in the front region cylindrical explosive-charge 14 and explosive 16 on its rearwardly directed Upon the detonation of the explosive well-known, to such pressures behind (Fig. 1) is to be Which is arranged 13 of a hollowis backlined with convex surface 15. 16 it leads, as is the insert 12 that 6 the inwardly-arched insert centre 17 is everted forwardly in the effective direction 18 of the munition and the insert periphery 19 therebehind then so folds together about the axis 20 of the rotational ly- symmetrical insert 12 that the insert centre 17 results in the nose 21 of the projectile 11, and the insert edge 19 results in the projectile tail 22.

This axial eversion and rearward folding together of the insert 12 result, in the normal case, in a more or less cylindrical projectile ill having a distinct constriction 23, as indicated in a broken line in Fig. 1. Such a structure cannot, for aerodynamic reasons, fly in a directionally stable manner, but it executes a somersaulting or tumbling motion; from which it results that no great kinetic penetrating effect is achieved in a target object, unless the projectile ll' even deviates more or less severely from the axial effective direction 18, thus misses the target. In addition to this there exists, in the region of the constriction 23, the risk of a rupturing into several parts which then continue to more at a different velocity and possibly also on different flight paths, which leads to a further reduction of the effect in the target.

What is striven for, on the contrary, is a projectile 11 which is as far as possible elongated and flightstable, which is distinguished from the previously 1 7 considered, constricted cylindrical shape more especially by a tail 22, clearly developed transversely to the longitudinal axis 20, behind a compact projectile body without appreciable (breakage-endangered) constrictions.

It has now surprisingly transpired that the ideal shape of the projectile 11 can be achieved in very good approximation and with high probability of reproduction if the rotationally- symmetrical insert 12 is fashioned from material of high density contrary to the conventional technology for iron inserts not as a truncated hollow cone and not even as a hollow spherical segment, but as a shallow plate-shaped or cap-shaped structure with an edge region 25 which surrounds in a flange-shaped manner a shallow, spherical-segment-shaped dome 24 of substantially constant material thickness and the material thickness 26 of which extends degressively towards the periphery. Such an insert 12 produces, with a relatively widely and steeply radially outstanding tail 22 (for the stabilisation of the projectile flight), a uniform long stretch of the projectile 11 with a relatively slight shaft diameter and thus a high penetrating power into a hard-armoured target object.

For the production of such an insert 12 advantageously a start is made from a plane-parallel round 28, which is flattened in a multiply- conical manner with very large frustoconical angles in an encircling edge 8 region 25 on one surface 15 by surface working, for example by milling. In this way there emerge ring zones 30 having angles of inclination with are increasingly larger towards the periphery 19 (relative to the original plane of the surface 15). As shown in Fig. 3, it is already sufficient to cause two such ring zones 30 of different inclination to succeed one another along the periphery 19 in the direction of the centre 17, before the transition into the original plane-parallel surface 15 of constant material thickness 26 is effected. The radially measured width of a ring zone 30 lies in each case approximately in the order of magnitude of a good 30% of the radius 27 of the round 28, and each ring zone 30 following towards the periphery 19 has approximately 1 degree of additional inclination relative to the plane of the original surface 15.

The round 28 prepared as described is given the final shape of the degressively-plate-shaped insert 12 advantageously by extrusion-transformation in the course of the pressing of its non-trimmed (translator's note: can also mean "unworked") front surface 31 against a polished die 32 designed complementarily to the desired shaping (thus convexly). This rotates about the axis of symmetry 20, and the still substantially planar round 28 is pressed in front thereof by means of a sliding or rolling tool, until both surfaces 15, 31 substantially follow the shape of the die 32. Structure variations, which occurred as a 1 9 result of the production of the narrowed ring zones 39, have converted back by the effect of the extrusion (translator's note: can also mean "flow-pressing") transformation into an undisturbed, compacted and thus consolidated metal structure.

The radial width of the edge region 25 encircling approximately in the original plane of the round in a flange-shaped manner about the dome 24 lies in the order of magnitude of just over the width of the outermost ring zone 30 encircling at the periphery 19. Advantageously this edge region 25 is inclined as a whole slightly conically relative to the original plane of the round, as shown in Fig. 2/4 with an exaggerated angle of incidence 33.

In conclusion, the insert periphery 19 is removed by turning, in order to ensure a good seat in the inner-wall receiver 34 of the f ront region 13 of the casing, and an encircling chamfer is turned onto the front edge. Af ter the frontal insertion of the insert 12 into the casing 14 there engages between this chamfer 35 and the inner jacket surface of the case 14 a retaining ring 36 which is profiled in a wedge-shaped manner and which is connected in a force-locking or form-locking manner to the casing and, in this respect, both axially secures the insert 12 and radially centres it with respect to the axis of symmetry 20.

Claims

Patent claims

1. A rotational ly- symmetrical proj ectile- forming insert (12) having locally different material thickness (26), more especially for armour-piercing seeker-fuze submunition, characterised in that it is shaped as a round (28) which is inwardly arched in a plate-shaped manner and which has a shal low- spherical -cap- shaped hollow dome (24) having a substantially constant material thickness (26), along the periphery (19) of which ring zones (30) having angles of inclination (29) growing increasingly towards the periphery encircle, which culminate in the radial direction in an encircling edge region (25), extending approximately in the cross-sectional plane, of narrowed material thickness (26).

2. An insert according to claim 1, characterised in that shallow-conical concentric ring zones (30) are provided.

3. An insert according to claim 1 or 2, characterised in that the thinned ring zones (30) are worked-in in one surface (15) of the round (28) along with removal of material.

4. An insert according to claim 3, characterised in that the thinned ring zones (30) are overformed (translator's note: can also mean "shaped by reworking") in a stretching-elastic manner.

1

5. An insert according to claim 4, chcracterised in that the round (28) is pressure-moulded against a die (32).

6. An insert according to claim 5, characterised in that the round (28) is pressure-transformed (translator's note: can also mean "transformed by hydraulic pressure") with its unworked planar front surface (31) butting against the polished convex structure of the die (32).

lo

7. An insert according to one of the preceding claims, characterised in that the edge region (25) encircling in a flange-shaped manner around the shallowly-arched dome (24) is inclined slightly in the direction of the arching of the dome (24), out of the insert cross-sectional plane wi th the periphery (19) forwards, in a shallowlyfrustoconical manner.

8. An insert according to one of the preceding claims, characterised in that it consists of tantalum of copper.

9. An insert according to one of the preceding claims, characterised in that its periphery (19) has a forwardly narrowing chamfer (35).

10. An insert according to claim 9, characterised in that it is supported in the transforming direction, axially forwardly, with its edge chamfer (35) against a wedgeshaped retaining ring (36).

-Iolf i 2_ 1 Amendments to the clairns have been filed as follows A projectile forming insert, for an armour piercing seeker-fuze submunition, comprising a rotationally symmetrical disc-shaped body having a domed circular central portion of substantially constant thickness, and an annular intermediate portion between the central portion and a peripheral portion; wherein the intermediate portion is shaped so that it is inclined to a plane normal to the central axis of the insert at angles which increase from a minimum adjacent to the central portion to a maximum adjacent to the peripheral portion; and wherein the annular peripheral portion tapers to decrease in thickness as it extends substantantially radially outwards to a periphery of the body.

2. An insert as claimed in Claim 1 characterised in that the intermediate portion decreases in thickness from a maximum adjoining the central portion to a minimum adjoining the peripheral portion.

3. An insert as claimed in Claim 1 or 2 having a concave front surface and a convex rear surface, characterised in that the rear surface of the peripheral portion is inclined to said plane.

4. An insert as claimed in Claim 3 characterised in that the front surface of the peripheral portion is inclined at i Ki's 1 1 a lesser angle to said plane.

5. An insert as claimed in Claim 3 or 4 wherein the front surface of the intermediate portion is domed or curved to part-spherical form.

6. An insert as claimed in any one of Claims 1 to 5 made of tantalum or copper.

7. An insert as claimed in any one of Claims 1 to 6 having a forwardly and outwardly directed chamfer at its periphery.

A projectile f orming insert substantially as 15 hereinbefore described with reference to FIGURE 2 of the accompanying drawings.

9. An insert as claimed in Claim 1 made f rom a disc blank by a method comprising the steps of:- (a) removing material from annular zones of one side of the blank so that said zones taper conically, (b) deforming the blank so as to cause the central portion and the annular zone adjacent thereto to become domed.

10. An insert as claimed in Claim 9 wherein in step (b) the deformation is performed so that the peripherally q outer one of the annular zones becomes conically inclined.

11. An insert as claimed in Claim 9 or 10 wherein step (b) is performed by forcible engagement between a convex 5 die and the other side of the blank.

12. An insert as claimed in Claim 11 wherein in step (b) said blank is deformed by hydraulic pressure or by a sliding or rolling tool applied to said one side.

13. An insert as claimed in Claim 9, 10, 11 or 12 wherein the periphery of the blank is trimmed after step (b).

14. An insert as claimed in Claim 13 wherein a peripheral chamfer is formed on the periphery at the junction with said other side.

15. A projectile forming insert formed by a method substantially as hereinbefore described with reference to 20 FIGURES 2, 3 and 4 of the accompanying drawings.

16. An insert as claimed in any preceding claim and arranged in a submunition for forming a projectile as shown in full lines in FIGURE 1 of the accompanying drawings.

17. An insert as claimed in Claim 13 as appended to Claim 7 or 14, wherein the chamfer is engaged by a wedge-shaped 1 1 -kpr 1 retaining ring of the submunition.

18. An insert as claimed in any preceding claim and disposed in a submunition substantially as hereinbefore described with reference to FIGURE 2 of the accompanying drawings.

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