ENGIN EXPLOSIF A FRAGMENTATION

EXPLOSIVE DEVICE

Abrégé anglais

ABSTRACT OF THE DISCLOSURE
Improvements in or relating to an explosive device
A hollow controlled fragmentation head for an
explosive device, which comprises a double-walled
cage whose outer wall is constituted by a helix of
wire formed at regular intervals with notches which
extend over a fraction of the wire thickness and whose
inner wall is a continuous wall bounding a chamber
adapted to receive an explosive charge, the outer and
inner walls enclosing between them a plurality of
shrapnel forming elements.

Revendications

The embodiments of the invention in which an
exclusive property or privilege is claimed are defined as
follows:
1. A hollow controlled fragmentation head for an
explosive device, which comprises a double-walled cage whose
outer wall is constituted by a helix of wire formed at regular
intervals with notches which extend over a fraction of the
wire thickness and whose inner wall is a continuous wall bound-
ing a chamber adapted to receive an explosive charge, the
outer and inner walls enclosing between them a plurality of
shrapnel forming elements.
2. A hollow controlled fragmentation head for an
explosive device, which comprises a double-walled cage whose
outer wall is constituted by a helix of wire formed at regular
intervals with notches which extend over a fraction of the
wire thickness and whose inner wall is a continuous wall
bounding a chamber adapted to receive an explosive charge,
adjacent turns of said helix of wire be.ing free from bonding
to each other, the outer and inner walls enclosing between
them a plurality of shrapnel forming elements.
3. A head according to claim 1 or 2, wherein the
shrapnel forming elements form an intermediate layer.
4. A head according to claim 1 or 2, wherein the
shrapnel forming elements are partially received in gaps
between turns of the prenotched wire.
5. A head according to claim 1 or 2, wherein
said notches delineate fragments with wire and wherein the
shrapnel forming elements and the fragments delineated in
the wire by the notches therein are of such dimensions that
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the mass of the shrapnel forming elements is less than that
of the fragments.
6. A head according to claim 1 or 2, wherein said
notches extend from the wire inside surface radially of the
cage.
7. A head according to claim 1 or 2, wherein
said shrapnel forming elements are steel balls.
8. An explosive device containing a hollow
controlled fragmentation head according to claim 1 or 2.
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Description

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Improvement~ ln or relatin~ to an explosive device
BACKGROUNG OF THE INVF,NTION
- Thi~ invention relates to an explosive device9 and
more particularly to a h~llow controlled fragmentatlon
head for an explo~iYe device and to a novel 7 rapid
and low-cost technology ~or producing an e~plo~ive
fragmentation device.
In explo~ive dev~ces ~uch as shells it ~s conventional
to use a pro~ectile head consist~ng o~ ~ fragmentation
member. In an embodiment described e.g. in United
States Patent No. 2,933,799, the gragmen-
tation member is devised ~rom a wire notched at regular
interYal~ and c~iled helically, with contiguous turn~
welded together~ In thi~ system the notches ~erve &~
weak zones wh~ch bo~st fragmentat~on of the projectile
head by the explo~on o~ the explo~ive charge. Fragmen-
tation gives good short-distance ~topping power.
However, welding the turns together is time-c~nsumi~g.
In another construction9 de~cribed in Ge~m~n Patent
NoO 2r310,667, the projectile head
consi~t~ of a hollow ~ember having steel ball~ contained
between the pro~ectile outer casing and an inner tube
arQ~nd ~he e~plosiYe charge. In this ~hell the veloci-
ty imparted to the ball~ by explosion of the charge is
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very limited, mainly because the shock wave whichrut)tures the inner tube partially passes between the
balls, with the result that not all the energy produced
by the explosion is concentrated on the balls. Also,
manufacture of a projectile head of this kind is
relatively complex and not readily applicable to
small devices.
Summing up the properties of known fragmentation heads,
it can be stated inter alia that :
(a) They are effective at short range but far less
so a-t long range;
(b) Thei.r manufacture is complicated or time-consuming.
SUI~ARY OF THE INVENTION
It is therefore an object o~ the invention to provide
a controlled fragmentation explosive device with
improved long-range stopping power, yet which will
remain sufficiently reliable and simple and rapid to
manufacture even in the case of small projectilesO
According to this invention there i.s provided a hollow
controlled fragme~tation head for an explosive device,
which comprises a double-walled cage whose outer wall
is constituted by a helix of wire formed at regular
intervals with notches which extend over a fraction of
the wire thickness and whose inner wall is a con-tinuous

~ll bounding a chamber adapted to receive an explosive
charge, the outer and inner walls enclosing between
-thern a plurality of shrapnel forming elements.
Preferably the shrapnel forming elementsform an
intermediate layer.
Advantageously -the shrapnel forming elements are
partially received in the gaps between turn gaps of
the prenotched wire.
Conveniently the shrapnel forming elements and the
fragments delineated in the wire by the notches therein
are of such dimenslons that the mass of the shrapnel
forming elements is less than that of the fragments.
Preferably said notches extend from the wire inside
surface radially of the cage.
Advantageously said shrapnel formirlg elements are
steel balls.
This invention also relates to an explosive device
containing such a head.
A preferred hollow head in accordance with the inven-
tion provides advantageous stopping power by optimiz-
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in~ the velocity of the prenotched fragments, thevelocity thereof which is produced by the shock wave
of the explosion being appreciably better than for
the known projec-tiles~ Also, it is a simple and rapid
matter to manufacture embodiments of the invention in
which the turns of prenotched wire are not bonded
to~ether and the head is in the form of an independent
cage. The cage can be produc~d separately, then
positioned readily in a variety of projectiles since
the envelope or casing thereof can be manufactured in
t~o parts.
In order that the invention may be more readily under-
stood, and so that ~urther ~eatures thereof may be
appreciated the invention wil.l now be described by
way of example with reference to the accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a sectioned view, with parts broken away,
of a first embodiment of a head in accordance with
the invention, and
Figure 2 is a sectioned ~iew, with parts broken away, of
a second embodiment of a head in accordance with the
invention~
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1~'r',SCRIPTION OF EXEMPLARY Er~BODI~ENTS
A hollow head in accordance with the invention
comprises a double-walled cage 10 adapted to be placed
in an explosive projectile or shell. The cage 10 has
an outer wa11 1, an inner wall 2 and a number of steel
shrapnel forming elements 3 which can be of any shape,
e~g. steel balls, and which are contained between the
two walls 1 and 2c The hollow interior 20 of the cage
10 is adapted to receive an explosive charge. The
outer wall 1 consists of a helically wound rectangular
sectioned wire 4. The wire 4 is prenotched at regular
intervals over a fraction of its thickness from its
inside sur~ace radially of the cage~ Some of the
notches 5 can be seen in the drawings. The notches 5
act as weak zones which bound fragments 6. The
fragments 6 separate when the charge in the interior
or chamber 20 explodesO The turns of the prenotched
wire 4 are no-t bonded together in any way.
The steel elements 3 are contained between the walls
1 and 2. In the embodiment of Figure 1 the elements
3 are steel balls which form an intermediate layer.
The embodiment shown in Figure 2 is the same as that
shown in Figure 1 save that the steel balls 3 are
received partially in the gaps be-tween adjacent turns
o~ the prenotched wire 4. This feature is advant~

ageous for the preparation of small hollow heads which,
despite their size, have a powerful impact force
In the preferred embodiments the steel elements 3 and
the fragments 6 are of dimensions such that the mass
of the elmen-ts 3 is less than the mass of the fragments
6. Consequently, the velocity imparted to the fragments
6 by the explosion is high enough to ensure good long-
range impact.
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