Note: Descriptions are shown in the official language in which they were submitted.
CA 02333522 2000-11-27
1
IGNITING THE PROPELLANT CHARGE POWDER IN A PLASTIC
CARTRIDGE, ESPECIALLY FOR BOLT-FIRING TOOLS
The invention relates to ignition of the propellent-
charge powder of a plastics cartridge, in particular
for bolt-firing tools, according to the preamble of
claim 1.
Provided that they use solid matter (propellent-charge
powder) as propellent, the cartridges of bolt-firing
tools on the market today are reacted by means of
mechanical energy transmission (impact of a striking
pin on the igniting mixture). The application of
force, which is always necessary in this connection in
order to tension the firing spring, is considered to be
too wearing in continuous operation by the manufacturers
of the bolt-firing tools.
Such a cartridge according to the prior art is known
from DE 44 44 095 C2. It comprises a cup-shaped base
portion, in which the propellent-charge powder is
arranged, and a cover, which comprises a plurality of
layers. The ignition takes place by way of a striking
pin on an igniting composition arranged between the
layers of the cover.
The underlying object of the invention is to improve
ignition of the p:ropellent-charge powder of a plastics
cartridge accordi;r~g to the preamble of claim 1, in such
a way that said ignition is fatigue-proof in continuous
operation.
This object is achieved i.n accordance with the
invention as a re;~ult of the fact that the ignition
takes place by means of an electric discharge or by
means of laser light.
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Both types of ignition are fatigue-proof and render
possible a reliable ignition.
The ignition can act directly on the propellent-charge
powder, or by way of an igniting composition. For this
purpose, an igniting composition which can ignite the
propellent-charge powder is advantageously arranged in
the cartridge, on which igniting composition the
ignition acts.
In this connect~'_on, the igniting composition can be
arranged on the cover, or at the edge of the cartridge,
between the base portion and the cover.
In a first advantageous embodiment, the ignition
advantageously takes place by way of a high voltage
generated, for example, by a piezoelectric crystal.
It is advantageous for the first pole for the ignition
to be an electrically conductive spike stabbed through
the cover, and t:or the other pole to be either a second
electrically conductive spike or an adjacent metal
block.
In an alternative advantageous embodiment, the ignition
advantageously takes place by means of laser light,
more precisely by means of a laser diode which is
placed on the cover.
In this connection, the ignition can very suitably take
place indirectly or directly.
Indirect ignition is distinguished by the fact that the
ignition takes place by means of thermal excitation of
one or more added substances (for example graphite) in
the igniting composition or propellent-charge powder,
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the added substances having an absorption over a wide
wavelength range.
Direct ignition is distinguished in that the ignition
takes place by means of excitation of the molecules of
the igniting composition or propellent-charge powder.
Irradiation takE:s place with laser light of precisely
the wavelength that raises the molecules of the
igniting composition or propellent-charge powder to the
energy level at which exothermal disintegration takes
place.
Further feature:> of the invention emerge from the
figures, which are described in the following and in
which:
Figure 1 shows an electrical ignition by way of two
spikes and an igniting composition;
Figure 2 shows a.n elect.rical ignition by way of one
spike and a metal block as second pole and an igniting
composition;
Figure 3 shows a.n electrical ignition similar to Figure
1, but here the igniting composition is arranged in the
centre of the cartridge;
Figure 4 shows a.n electrical ignites similar to Figure
3, but without the igniting composition;
Figure 5 shows a.n ignition by means of laser light,
with there being' an igniting composition; and
Figure 6 shows an ignition with laser light but without
an igniting composition.
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Figure 1 shows a plastics cartridge comprising a cup-
shaped base portion 2, in which the propellent-charge
powder 1 is arr~~nged, and a cover 3. The base portion
2 has a circumfe:rential collar, with an igniting
composition 4 being arranged between the base portion 2
and the cover 3. The ignition takes place through the
cover 3 having t.wo spikes 5, 6 made of electrically
conductive material. A high voltage is applied to
these spikes 5, &, for example by means of a
piezoelectric crystal.
In Figure 2, instead of the second spike 6 in Figure l,
an earthed metal block 7 is arranged underneath the
collar and thus the igniting composition 4. Another
spike can also additionally be located on the metal
block 7.
In the embodiment of Figure 3, the igniting composition
4 is arranged in the centre of the cartridge. The
igniting composition 4 can, for example, be arranged in
a plastics cartridge directly above the propellent-
charge powder 1 or deposited thereon.
In the embodiment of Figure 4, an igniting composition
is not used. Two spikes 5, 6 are stabbed directly into
the cover 3 or through the latter into the propellent-
charge powder l, and a discharge is brought about
between them.
In Figures 5 and 6, laser light 9 through the cover 3
ignites an igniting composition 4 (Figure 5) or the
propellent-charge powder 1 directly (Figure 6). In
order to do this, a laser diode 8 is preferably placed
directly onto the cover 3.
In this connection, the ignition can take place in two
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ways, depending on the wavelength of the irradiated
light:
1. Indirectly, by means of thermal excitation of one
or more added substances (for example graphite),
which have absorption over a wide wavelength
range. These hot particles then ignite the
igniting composition;
2. Directly, by means of excitation of the molecules
of the ign_Lting composition. In this connection,
irradiation takes place with laser light of
precisely t;he wavelength that raises the molecules
of the ign~_ting composition (for example potassium
benzanate) to the energy level at which exothermal
disintegration takes place (unimolecular,
exothermal disintegration).
