METHOD OF INITIATING EXTERNAL EXPLOSIVE CHARGES AND EXPLOSIVE-CHARGED ACTION ELEMENTS FOR THESE
TECHNICAL FIELD The present invention relates to a method of initiating at least one first external explosive charge by means of a kinetic impulse which is transferred to the said first external explosive charge by splinter bodies, directed towards this first external explosive charge and flying freely at high speed, which have separated from a second explosive-filled action element A, initiated on own initiative and provided with an outer shell which surrounds the explosive and, upon detonation thereof, forms splinters.
The invention also relates to an explosive-charged action element A, provided with a splmter-formmg outer shell, intended to release, upon detonation of its own explosive charge, splinter bodies flying freely at high speed and intended to be used, according to the method according to the invention, to initiate at least one external explosive charge by transferring a sufficient quantity of kinetic impulse to the said external explosive charge to initiate the same to detonation.
The invention further relates to a splinter body tailored to the implementation of the said method of initiating external explosive charges and forming part of the herein utilized splinter shell.
The invention is especially suitable for combating an incoming explosive-charged enemy missile or some other unit which can be combated by means of splinter bodies configured according to the invention, such as, for example, artillery shells, dropped bombs or aircraft, watercraft or land craft, etc., which can be initiated with the specified invention, the explosive of the combatable unit being initiated to immediate detonation
by means of splinter bodies directed towards this explosive at high speed by an external explosion.
PROBLEM DEFINITION AND BACKGROUND TO THE INVENTION It has previously been known that explosives can be initiated to denotation by the kinetic impulse from large splinters which hit the explosive at high speed. This knowledge has been utilized, inter alia, in the design of missiles intended to combat enemy explosive- charged missiles incoming towards one's own territory. It will then, in fact, be sufficient for an own antimissile second missile to enter into the vicinity of the first enemy incoming missile (s) m order for the own second missile to be able to eliminate the incoming first missile (s) with splinter bodies, which are formed or released and are directed at high speed towards the incoming first missile upon detonation of an explosive- charged action element forming part of the own second missile and provided with a splinter-forming shell.
The drawback with this approach has previously been that large splinters which hit the explosive charge of the incoming missile at high speed have been needed to ensure that this would be initiated to detonation. This gave rise to the need to provide the own anti-missile second missile with a large action element comprising a thick splmter-forming outer shell and a powerful explosive charge fragmenting the splinter shell, which automatically meant that the weapon system as a whole became large and expensive. One example of an American weapon system of this kind is the so-called Patriot robot .
PURPOSE OF THE INVENTION AND ITS SPECIAL FEATURES The mam object of the present invention is to achieve an improved method of initiating a first external explosive charge, an improved explosive-filled action element for implementation of the said method, and a splinter body tailored to the implementation of the
said method, which initiation method, action element and splinter body substantially reduce, preferably eliminate, the abovementioned problems, the initiation method, the favourable effects of the action element and of the splinter body being able to be better utilized than previously.
A further object of the present invention is to achieve a method of making it possible to markedly reduce the size of the action elements forming part of such antimissile missiles without thereby reducing the capacity of the action elements to initiate the explosive charges in such incoming missiles at which the antimissile missiles might be fired.
The said objects, and other aims which have not here been enumerated, are satisfactorily met by way of that which is defined in the present independent patent claims. Embodiments of the invention are defined in the independent patent claims.
Thus, according to the present invention, an improved method has been achieved of initiating at least a first external explosive charge by means of a kinetic impulse, which method is characterized in that the splinter bodies released from the outer shell of the action element, upon detonation of the explosive charge forming part of the action element, have forcibly been given a shape having a large broadside in relation to their own mass, and in that these splinter bodies are accelerated evenly towards the said first explosive charge so that these splinter bodies will hit the said first explosive charge with their own broadside first and, in so doing, will supply a sufficiently high kinetic impulse to the first explosive charge over a sufficient area to initiate the particular explosive charge to detonation.
According to further aspects of the method according to the invention, it is the case:
that the division of the splinter shell of the action element into splinter bodies having a large broadside in relation to their own mass is ensured by the splinter shell being given different strength m its various parts, either by means of weak links m or by means of reinforcing counterstays against those parts of the splinter shell along which a division of the same gives the splinter bodies released from the splinter shell the desired shape;
that the said even acceleration of splinter bodies having a certain extent in the detonation direction of the explosive which accelerates the splinter bodies upon detonation is achieved by a retardation of the acceleration of the splinter bodies along that one of the edges (a) of the splinter bodies which will first be hit by a detonation wave from the detonating explosive, which retardation is tailored such that the detonation wave has time to reach the second edge (b) of the splinter body, which is not retarded in the same way, whereby the splinter body will be accelerated evenly away from the detonating explosive charge;
that the said even acceleration of splinter bodies having a certain extent m the detonation direction of the explosive which accelerates the splinter bodies upon detonation is achieved by the splinter bodies having been pre-given, by bevelling, a smaller thickness (ti3) along the edge which is last hit by the detonation wave from the detonating explosive.
Furthermore, for the implementation of the methods according to the invention, the tailored splinter body (5) forming part of the herein utilized splinter shell (7) is characterized:
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in that the splinter body has a broadside whose extent in the lateral direction substantially exceeds the thickness of the splinter body, and m that the said broadside, preferably, has the shape of a more or less flat circular, elliptical, rectangular or polygonal surface, alternatively xn that the splinter body has the shape of a relatively flat or flattened ellipsoid, rounded or polygonal lamina, plate or disc.
Further, according to the invention, the explosive- charged action element is characterized:
in that the said splinter bodies have been pre- guaranteed a configuration each having a large broadside facing in the acceleration direction of the splinter bodies.
According to further aspects of the explosive-charged action element, it is the case according to the invention :
that the splinter bodies forming part of its original shell, which forms splinters upon detonation of the explosive, have the shape of polygonal, rounded or oval plates, laminae or ellipsoids;
that its shell, which forms splinters upon detonation of the explosive, is produced by powder- metallurgical methods comprising splinter bodies inserted in a matrix produced by sintering of a metallic powder material and each having a large broadside relative to the own mass of the respective splinter body and having a higher intrinsic strength than the matrix;
that the powder-metallurgically produced matrix of the splmter-formmg shell, in which the splinter bodies are inserted, is configured such that it covers
with a sufficient quantity of sintered powder material that part (a) of the respective splinter body which will first be reached by the detonation wave from the explosive charge detonating the action element that the acceleration of this first part (a) away from the detonation point is delayed for a sufficient period of time to allow it (a) to be accelerated away from the detonation parallel with that part (b) of the same splinter body which is last reached by the same detonation wave and which is not correspondingly retarded, i.e. is unretarded in relation to the first part (a) ;
that that part (b) of the same splinter body which is last reached by the same detonation wave is covered with a smaller quantity of sintered powder material than that part (a) of the respective splinter body which will first be reached by the detonation wave from the detonating explosive charge of the action element;
that it further comprises counterstays, disposed on the outside of the splinter shell and having such a thickness (ti2, ti3) and extent that the acceleration of the splinter bodies forming part of the splinter-forming shell of the explosive charge away from the detonation is retarded along the edges (a) which are first touched by the detonation wave formed upon detonation of the explosive for a sufficient period of time to allow the splinter bodies to be accelerated evenly away from the detonation;
that the individual splinter bodies are configured like disc plates bevelled along the edge (b) last hit by the detonation wave, such that the acceleration of the splinter bodies forming part of the splinter-forming shell of the explosive charge away from the detonation is retarded, in relation to the acceleration of the bevelled edge (b) , along the edges
(a) which are first touched by the detonation wave formed upon detonation of the explosive, for a sufficient period of time to allow the splinter bodies to be accelerated evenly away from the detonation;
that the shell which surrounds the explosive and forms splinters upon detonation of the explosive, on its inner side facing towards the explosive, has been provided with at least one shock wave trap, in the form of at least one shock-wave-influencing material lining, with a view to guaranteeing a predetermined division of the splinter shell into splinter bodies of the desired size and shape;
that it comprises a detonator for initiating the explosive charge forming part thereof, this detonator, which is disposed at one end of the explosive charge, having been combined with a wave shaper ;
that it comprises multi-initiation detonators having a plurality of initiation sites, disposed along the outer face of the explosive charge, for instantaneous initiation of the explosive charge.
ADVANTAGES AND EFFECTS OF THE INVENTION
The basic concept behind the present invention is thus to configure the components forming part of the own action element so that the splinter bodies shaped by the splinter shell of the own action element acquires, compared with their own mass, a large surface facing in the direction of an incoming enemy missile, shell, bomb, craft, etc. and a correspondingly small thickness in the same direction, which means that that side of the splinter bodies, hereinafter referred to as the broadside, which is directed towards and hits the incoming enemy missile, etc., comprising the above and below named first external explosive charge, shall have the shape of laminae, plates, discs, ellipsoids or
equivalent. The invention further includes an assurance that these splinters of laminar, plate-like, ellipsoid or other equivalent configuration shall hit the intended target at a sufficiently high speed with their own broadside first and, m so doing, transfer a sufficient kinetic impulse to the explosive charge of the first incoming enemy missile over a sufficient area to initiate the explosive to detonation. This specific configuration of the splinter bodies thus offers a possibility of hitting the target with splinter bodies which, m the event of a hit, provided that they have thus initially been given a sufficiently high speed and despite their limited own mass, transfer a sufficient quantity of kinetic impulse over a sufficient area of explosive to ensure an initiation of the explosive charge forming part of the combated missile. By impulse is here meant, m somewhat simplified terms, a change in the momentum, i.e. the product of mass times speed in a certain direction, of an object.
Since the above-indicated shape of the splinter bodies configured according to the invention has been able to be given a large surface compared with their own mass, the splinter-forming shell of the action element has been able to be made thinner and hence lighter, whilst, at the same time, a correspondingly lesser amount of detonating charge of explosive inside the splmter- formmg shell will be needed to give the splinter bodies released therefrom upon detonation of the explosive charge a sufficiently high initial speed m the direction of the target, i.e. of the foreign missile. This general basic notion thus offers the prospect of markedly reducing the size of the action element which is necessary to combat foreign incoming explosive-charged missiles, and hence the size of the entire weapon system m question and the costs of the same .
In order for the laminar, plate-shaped or ellipsoidal, etc. splinters to produce the effect outlined above, it is required, however, that, firstly, they maintain their original shape until hitting the target and, secondly, they actually hit the target with their broadside first.
The first of the above-specified conditions means that the splinter shell from which the splinters are released, upon detonation of the explosive charge disposed inside the splinter shell, is fragmented only at precisely those points and along those parting lines which were originally presumed, and this can be ensured by means of weaker sections, for example in the form of material thinnings, at the said points and along the desired parting lines, built from the outset into the splinter shell. A better solution to the same problem is, however, to produce the splinter shell by powder metallurgy methods, pre-produced splinter bodies being inserted into a matrix, produced by powder-metallurgy methods, which separates the splinter bodies one from another and from the explosive charge and which, by virtue of the fact that the matrix, upon detonation of the explosive, surrounds the splinter bodies, gives these a gentle acceleration, which prevents the splinter bodies from fragmenting and ensures that these are accelerated in the desired direction, namely in the direction of the incoming enemy missile, etc. This process for the production of the splinter shells therefore has the advantage that, by producing the splinter bodies separately, it is possible to give them the most favourable configuration for each individual case and, moreover, to give them a substantially higher strength than the matrix material which initially holds the splinter shell together. Consequently, it is thus possible effectively to prevent an undesirable fragmentation of the splinter bodies and to ensure that these, when they are released from the splinter shell and begin their flight towards the target, acquire
precisely that configuration which is designed for the purpose .
The division of the splinter shell into splinter bodies of a desired shape, irrespective of whether the splinter shell is produced by powder-metallurgical methods or not, might also be to some extent ensured by specific counterstaying elements disposed on the outside of the splinter shell along desired rupture lines between the desired splinter bodies.
In order to reinforce and further ensure the division of the splinter shell into splinter bodies of desired size and shape along predetermined rupture lines or along the space between prefabricated splinter bodies baked into a powder-metallurgical matrix, and in order, at the same time, to prevent an undesirable further fragmentation of the splinter bodies, the inner side of the splinter shell can be provided with shock wave traps in the form of one or more layers of linings of material which exhibits strongly different acoustic properties from the rest of the splinter shell. As examples of materials which can be used as such shock wave traps, plastics of different hardness and density can be cited.
The above-specified other conditions for the splinter shell configured according to the invention, giving the desired effect in the form of a detonation of the explosive charge in a foreign missile or in another target comprising an explosive charge, for example an artillery shell, bomb, etc. according to the above, namely that the splinter bodies according to the invention shall hit the target with their own broadside first, mean that the splinter bodies, upon detonation of their own explosive charge and their associated own release from the splinter-forming shell or the matrix, must be accelerated evenly towards the target without any form of simultaneous rotary motion.
Initially, this means that all splinter bodies must be given constant and uniform acceleration conditions, which, when the explosive charge is initiated from its one end, can be relatively easily arranged by means of a wave shaper which is installed in the initiation end and compensates for the gradual changing, by the detonation wave formed in the spot initiation, of the radius of curvature of its own detonation wave during its propagation through the explosive charge from its initiation end to its other, opposite end.
A dearer and more complex solution to the same problem is to provide the charge with a detonator for multi- initiation, which, along its own outer face, gives an instantaneous initiation over the whole of the circumference (envelope surface) of the charge.
The even acceleration which is sought for the method according to the invention further means that the splinter bodies, as already indicated, are prevented from being given any form of rotated motion in connection with their release from the splinter shell surrounding the explosive, by the detonation of the latter, and their acceleration towards the target. For the splinter bodies according to the invention, it is important, as pointed out previously, that these should each have at least one large surface compared with their own volume and that they should hit the target with this own broadside first. The own surface requirement can be met by each splinter body having a certain extent in the longitudinal direction of the original splinter shell. This means, in turn, that one edge/side of each specific splinter body will be hit by the detonation wave from the detonating own explosive before its opposite edge side, which in turn, if no special measure were taken, would automatically result in the splinter, upon detonation of its own explosive,
having been given a rotary motion about an axis midway between the said edge sides.
According to one development of the invention, it has proved possible to ensure the even acceleration of the splinter bodies, however, with the aid of well- dimensioned counterstays placed on the outer side of the original splinter shell. These counterstays, which can form part of the original splinter shell matrix in the form of a sectionally arranged, increased material thickness towards the outer side of the splinter shell, or alternatively as separate counterstays disposed on the outer side of the splinter shell. These counterstays thus have the function of offering exactly the right resistance when the detonation wave first reaches the first one edge side of the respective splinter body and, at the same time, of preventing the first hit edge/side of the splinter body from managing to be accelerated away from the detonation front before the detonation wave reaches the opposite edge side of the same splinter body.
Through the use of counterstays of the above-specified type, it has thus proved possible to resist, i.e. retard, the acceleration of that edge/side of the respective splinter body which has first been reached by the detonation wave until the detonation wave reaches the opposite edge side of the splinter body, the result being that the splinter body is accelerated evenly away from the detonating explosive. In a splinter shell produced by powder-metallurgical methods, such counterstays, for example, could be formed by machine-cutting out of the splinter shell matrix produced by powder-metallurgical methods. Another method used for the same purpose would be to configure the individual splinters as disc plates bevelled along the edge which is last hit by the detonation wave.
The invention has been defined in the subsequent patent claims and it shall now be described somewhat more closely m connection with the appended figures.
Further advantages and effects will emerge m the course of study and consideration of the following detailed description of the invention, including a number of its advantageous embodiments, the patent claims and the accompanying drawing figures.
LIST OF FIGURES
With reference to the appended figures,
Fig. 1 shows in diagrammatic representation the principles behind the use of the invention m the combating of an incoming enemy missile, Fig. 2 shows m diagrammatic representation a particularly advantageous form of the splinter bodies characteristic of the invention,
Fig. 3 shows m diagrammatic representation a sectional projection of an action element configured according to the invention,
Fig. 4 shows m diagrammatic representation a longitudinal section through a modified action element, and Fig. 5 shows m diagrammatic representation an enlarged detail from Fig. 4.
DETAILED DESCRIPTION OF AN EMBODIMENT
Fig. 1 shows diagrammatically and specifically an explosive-charged enemy missile 2 incoming towards a target 1, hereinafter referred to as the first missile 2. For combating of this first missile 2, an own missile 3 equipped according to the present invention, hereinafter referred to as the second missile 3, has been launched, or alternatively fired, from another carrier such as an aeroplane, which second missile comprises an action element A, see Fig. 3. This second
missile 3 does not need to hit the first missile 2 in order wholly to be able to eliminate this. In the nearest position of the second missile 3 relative to the first missile 2, a charge with explosive 3', which charge forms part of the second missile 3, is instead initiated, splinters 4 configured according to the invention being dispatched in a swarm towards the first missile 2. In the event of a hit upon the explosive charge 2' of the first missile 2, this external explosive charge 2' is initiated by the said splinters 4. In order to ensure that the splinter 4 shot out from the second missile 3 shall actually transfer a sufficient quantity of kinetic impulse to the explosive charge 2' in the first missile 2 to detonate this charge 2', splinter bodies 5 characteristic of the invention, see Fig. 4, have been inserted into the splinter-forming outer shell 7 of the explosive charge 3' of the second missile 3 (indicated purely diagrammatically by means of a dashed line) . These splinter bodies 5, see Fig. 2, each have a large broadside 5' compared with their own mass, i.e. they have, for example, the shape of plates or ellipsoids or other laminar shapes which give the splinter bodies 5 large broadsides 5' but a limited thickness t, which broadside 5' is intended to hit the enemy, first missile 2. A particularly advantageous configuration of the splinter body 5 is a rounded button or coin shape 5 with the broadside 5' , which embodiment is illustrated in Fig. 2 and Fig. 3. However, any other embodiment which meets the characteristics characteristic of the invention is also conceivable. Such embodiments thus comprise, for example, button-shaped, coin-shaped, rectangular, square, polygonal and other shapes (here not further specified) . For optimal effect, it is essential that the splinter 4 formed upon detonation of the explosive charge 3' in the own second missile 3 comprises splinter bodies 5 having at least one side face 5' of the respective splinter body 5 which is
substantially large in relation to the mass of the splinter body 5 and its total volume.
The action element A, illustrated in Fig. 3, of the second missile 3 is thus provided with an inner explosive charge 3' and a considerable number of splinter bodies 5 gathered around the explosive charge 3' in a shell 7, which forms splinters upon detonation of said explosive charge. In Fig. 3, only one band of such splinter bodies 5, plus a solitary splinter body 5, has been drawn, but in reality the splinter shell 7 of the whole of the action element A shall contain such, see also Fig. 4.
As has already been pointed out, the splinter bodies 5 shall be accelerated evenly towards the incoming missile 2, so that the splinter bodies 5 hit the first, i.e. incoming missile 2 with their broadside 5' first. A method of achieving this effect is more closely illustrated in Fig. 4 and Fig. 5. The action element A illustrated in longitudinal section in these two figures 4 and 5 contains a said explosive charge 3' and a said splinter-forming shell 7 in which a suitable embodiment of the splinter bodies 5 is inserted. In addition, there is a detonator 8 for initiation of the explosive charge 3' . Inserted within the detonator 8 is a wave shaper 14. The wave shaper 14 comprises layers of, for example, air and metal (not more closely described here) . On the inner side 15 of the splinter- forming shell 7, which inner side faces towards the explosive charge 3' , there is disposed a shock-wave- damping lining 9 arranged to constitute a shock wave trap 16. This lining 9 comprises material combinations, preferably in a number of different material layers, with different acoustic properties, and has the function of ensuring that the splinter-forming shell 7 is fragmented in the right places without damage to the splinter bodies 5. As examples of suitable materials in the incorporated shock wave traps can be cited various
types of plastics which have characteristics favourable to the invention and, in particular, different hardness. Other favourable characteristics can be, for example, different density, etc.
From Fig. 4 and Fig. 5, it can further be seen that the explosive charge 3' is initiated at its one end by the detonator 8. It follows from this that a detonation wave will travel through the explosive charge 3' . This gradual displacement of the detonation wave through the explosive charge 3' has been illustrated with curved lines 10 and a detonation direction arrow 11. As can further be seen from Fig. 5 specifically, the detonation wave 10 will first reach that edge of the respective splinter body 5, which splinter body 5 has a certain defined extent in the detonation direction 11, which lies nearest in the detonation direction 11. In Fig. 5, this edge of the first splinter body 5 in the detonation direction has been denoted by a. If no specific measures had been taken, the edge a of the said first-coming splinter body 5 would have begun to be accelerated away in the direction of the arrow a' before the detonation wave 10 reached the other, opposite edge b of this splinter body 5, which second edge b is thus consequently accelerated away in the direction b' by the detonation wave 10, but somewhat later than the edge a. The result would thus have been that the splinter body 5 would have been given a rotary motion about an axis midway between the edges a and b. If, upon the detachment or formation of the splinter body 5 from the splinter shell 7, the two said acceleration directions a' , b' are parallel and the respective acceleration is equal in magnitude, no rotation occurs.
In order to avoid this undesirable effect, the matrix, see further below, which constitutes the coherent portion of the splinter shell 7 and in which the splinter bodies 5 are baked in, has been given
counterstays 12 and 13 of different thickness t12 and ti3 level with the edges a and b respectively of the splinter body 5, see Fig. 5. The splinter shell 7 therefore has a saw-toothed sectional profile. The result is that that part a of the respective splinter body 5 which is first reached by the detonation wave 10, i.e. its side edge a in Fig. 5, gets a larger counterstay thickness ti2 and hence a greater resistance to surmount before being accelerated away from the detonation wave 10 than does the part, i.e. edge, b, which the detonation reaches somewhat later, with the thinner counterstay thickness tχ3 of the splinter shell 7 to surmount. Given correctly dimensioned counterstay thicknesses 12, 13, the splinter bodies 5 can thus be given the even acceleration which is sought for the method according to the invention, that is to say that the said even acceleration of the splinter bodies 5 is achieved through a hindrance/retardation of the acceleration of the splinter bodies 5 along that one of the edges a of the splinter bodies 5 which will first be hit by a detonation wave 10 from the detonating explosive 3' , which hindrance/retardation is tailored such that the detonation wave 10 has time to reach the second edge b of the splinter body 5, the acceleration b' of which second edge b is unhindered/unretarded, i.e. which is not retarded in the same way as the first edge a, before the first edge a has been detached from the rest of the splinter shell 7 and has commenced its acceleration a' , whereby the splinter body 5 will be accelerated evenly away from the detonating explosive charge 3' .
The type of splinter shell 7 which is shown in Fig. 4 and Fig. 5 is meant to be produced by powder- metallurgical methods, which in this case would mean that prefabricated splinter bodies 5 are baked into a powder matrix which is sintered to a cohesive strength which is preferably given an at least somewhat lower
intrinsic strength than the splinter bodies 5 baked into it.
The saw-toothed profile, shown in Fig. 4 and Fig. 5, of the splinter shell 7 comprising the counterstays 12, 13 can then comfortably be formed by machine-cutting out of the sintered matrix material, so that a considerable quantity of matrix material, i.e. the counterstay 12 with the larger thickness ti2, remains at that edge a of the splinter body 5 which is first reached by the detonation wave 10, whereas a lesser quantity of matrix material, i.e. the counterstay 13 with the smaller thickness ti3, remains at that edge b of the splinter body 5 which is last reached by the detonation wave 10. The quantity of matrix material, i.e. the thickness between the counterstay 12 and the counterstay 13, viewed in a longitudinal section, expediently decreases rectilinearly between the said counterstays 12, 13
(Fig. 5) .
The invention is not limited to the illustrated embodiment, but can be varied in a variety of ways within the scope of the patent claims. It will be appreciated, for example, that the enemy target which is specifically described herein, i.e. the incoming missile 2 which is specified above in the illustrative embodiment can also be comprised by any other aerial, water or land target comprising an explosive which can be initiated according to the patent claims, for example a shell fired by means of a suitable barrelled weapon. In the same way, the own missile 3 may also be constituted by a barrelled projectile.
It will further be appreciated that, as previously indicated, the saw-toothed profile can be replaced by, for example, a bevel along the edge of the splinter body which is last hit by the detonation wave.
It will be appreciated that the number, the size, the material, the characteristics and the shape of the elements and components forming part of the action element A, for example the splinter bodies, the wave shaper, the shock wave traps, etc., are tailored to other incorporated elements or components and the enemy target (s) which the action element is intended to combat .