Note: Descriptions are shown in the official language in which they were submitted.
CA 02715806 2010-08-17
WO 2009/103409 - I - PCT/EP2009/000675
DESCRIPTION
Explosive projectile and method for the production
thereof
The invention relates to an explosive projectile having
a projectile casing which surrounds an internal area
which is filled with an explosive. The invention
furthermore relates to a method for producing the
explosive projectile.
DE 23 45 070 B2 describes an encapsulated explosive
which is made such that it can be handled easily, and
DE 38 43 443 Al discloses an explosive body. Various
explosive projectiles are disclosed, inter alia, in
DE 602 02 419 T2, DE 601 08 817 T2, DE 20 2004 019 504 U1,
DE 295 19 568 U1, DE 39 13 543 Cl and DE 196 26 660 C2.
Furthermore, EP 1 338 860 A2 discloses a method for
producing a large-caliber explosive projectile, in
which a plastic-bonded explosive charge is located in
the internal area of the projectile casing and is
incorporated in a plastic casing, which can be unfolded
and is introduced into the projectile.
If an explosive in liquid form is used, the internal
area of the projectile casing is filled with this
explosive, which is then cured. In this case, shrinkage
can occur, and cracks can possibly also be formed in
the explosive, both during casting and during curing of
the explosive. Shrinkage and cracks such as these
represent a not insignificant safety risk because the
shrinkage and cracks can very quickly change their
shape because of the high acceleration when the
explosive projectile is fired, and the heat in the
shrinkage and cracks can be so severely heated because
of the compression that this results in that this can
lead to ignition of the corresponding explosive.
CA 02715806 2010-08-17
WO 2009/103409 - 2 - PCT/EP2009/000675
Therefore, in general, after the explosive has been
introduced and cured, the explosive projectiles must be
checked by means of an X-ray installation for shrinkage
and cracks, and this is associated with a considerable
time and cost penalty.
The invention is based on the object of specifying an
explosive projectile in which the risk of inadvertent
ignition of the explosive on firing is less than in the
case of explosive projectiles with cured liquid
explosive. A further aim of the invention is to
disclose a method for producing an explosive projectile
such as this.
According to the invention, this object is achieved
with regard to the explosive projectile by the features
of claim 1, and with regard to the method by the
features of claim 7. Further, particularly advantageous
refinements of the invention are disclosed in the
dependent claims.
The invention is essentially based on the idea of using
a liquid explosive as the explosive, which does not
cure, but remains liquid, after being introduced into
the internal area of the projectile casing. In this
case, the explosive in the internal area of the
projectile casing is arranged in an elastic casing,
such that it is sealed in an air-tight manner.
The explosive projectile according to the invention
has, inter alia, the advantage that it can be produced
in a simple manner, since the explosive can be
introduced into the casing, which, for example, is
composed of plastic, while it is still outside the
projectile casing, and can be sealed in an air-tight
manner. This makes it possible to largely prevent the
occurrence of air bubbles within the liquid explosive,
for example by connection to an appropriate vacuum
CA 02715806 2010-08-17
WO 2009/103409 - 3 - PCT/EP2009/000675
device, at this point in time. Once the casing has been
closed in an air-tight manner, this is then introduced
into the projectile casing, together with the
explosive, for example from the mouth of the projectile
casing, with the elastic casing reliably preventing the
liquid explosive from inadvertently emerging from the
projectile casing, or air from inadvertently entering
the elastic casing.
The elastic casing must, of course, be composed of a
material which is compatible not only with the
explosive but also with the other materials used in the
projectile (to the extent that they come into contact
with the casing), such that the corresponding material
characteristics are retained over a relatively long
time period in the predetermined temperature range. It
is not unusual for the purchaser of corresponding
explosive projectiles to specify a useful live of, for
example, 25 years for such projectiles.
Preferably, the elastic casing is adhesively bonded in
one subarea to the inner wall of the projectile casing.
This means that the liquid explosive cannot move in an
undefined manner in the internal area of the projectile
casing. In this case, a free space should remain
between the elastic casing and the projectile casing,
in order to allow the elastic casing to expand in the
event of thermal expansion of the explosive within the
internal area, without deformation of the projectile
casing.
By way of example, the volume equalizing element may
consist of a container which is filled with a
compressible gas or a compressible liquid. The volume
equalizing element is preshaped, and is matched to the
planned position in the projectile ogive. During
insertion into the projectile, in a vacuum or at a
reduced pressure, the volume equalizing element is
CA 02715806 2010-08-17
WO 2009/103409 - 4 - PCT/EP2009/000675
preferably folded or compressed. The preshaping of the
volume equalizing element and the gas contained in it
relieves the load on the body after insertion again,
and, for example, merges itself into the ogive or onto
it. The adhesive should be applied in advance in the
area of the ogive, where the volume equalizing element
is seated, in order to create a uniform adhesive layer.
The adhesive can preferably be applied by spraying it
on.
Particularly when using explosive projectiles with nose
fuzes, care must be taken when choosing the free space
arranged at the front to ensure that the distance
between the elastic casing or the liquid explosive and
the fuze is not too great, in order to reliably ensure
defined initiation of the explosive.
Further details and advantages of the invention will
become evident from the following exemplary
embodiments, which will be explained with reference to
the figures, in which:
Figure 1 shows a longitudinal section through a
schematically illustrated spin-stabilized
explosive projectile (artillery projectile)
without a nose fuze, with liquid explosive
arranged in the internal area of the
projectile casing, and with a free space
being provided at the front, and
Figure 2 shows a view corresponding to Figure 1, with
a volume equalizing element which fills the
free space being arranged at the front.
In Figure 1, 1 denotes a spin-stabilized explosive
projectile which can be fired, for example, from an
armored howitzer and has a projectile casing 2 composed
of steel, which has an opening 3 at the front into
CA 02715806 2010-08-17
WO 2009/103409 - 5 - PCT/EP2009/000675
which an impact fuze, which is not illustrated, can be
screwed.
An internal area 5 is located in the projectile casing
2, which internal area 5 extends in the direction of
the longitudinal axis 4 of the explosive projectile 1
and holds explosive 6. In this case, according to the
invention, the explosive 6 is a liquid explosive, which
is surrounded completely and in an air-tight manner by
an elastic casing 7.
In the rear area of the projectile casing 2, the
elastic casing 7 is adhesively bonded to the inner wall
11 of the projectile casing 2, while a free space 9
remains at the front between the elastic casing 7 and
the projectile casing 2. This free space 9 is on the
one hand chosen such that the elastic casing 7, and
therefore the liquid explosive 6, can expand without
any impediment when temperature changes occur. On the
other hand, the distance between the elastic casing 7
and the fuze, which is not illustrated, is chosen so as
to reliably ensure that the fuze initiates the liquid
explosive 6.
In order to produce the explosive projectile 1, liquid
explosive 6 is first of all introduced into the elastic
casing 7, and this is then sealed in an air-tight
manner. The elastic casing 7, with the liquid explosive
6 located in it, is then introduced through the opening
3 into the internal area 5 of the projectile casing 2,
and is adhesively bonded to the projectile casing 2 at
the rear. The corresponding adhesive layer has been
annotated with the reference symbol 10 in Figure 1.
Figure 2 shows an explosive projectile 1' which
corresponds substantially to the explosive projectile 1
described above. The only difference is that the free
space 9 provided in the explosive projectile 1 is
CA 02715806 2010-08-17
WO 2009/103409 - 6 - PCT/EP2009/000675
filled by an elastic volume equalizing element 100,
which is prestressed. In this case, this volume
equalizing element 100 consists of a container 101 (for
example of a plastic film) in which a compressible gas
(or possibly a compressible liquid) is located. When
the liquid explosive is heated, the volume equalizing
element 100 is then compressed by the expansion of the
explosive 6. When the liquid explosive 6 cools down,
the volume equalizing element 100 in contrast expands,
in order in this case to compensate for shrinkage of
the explosive.
CA 02715806 2010-08-17
WO 2009/103409 7- PCT/EP2009/000675
List of reference symbols
1, 1' Explosive projectile, projectile
2 Projectile casing
3 Opening
4 Longitudinal axis
Internal area
6 Explosive, liquid explosive
7 Elastic casing
9 Free space
Adhesive layer
11 Inner wall
100 Volume equalizing element
101 Container
