Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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~ HIS INVENTION relates to a connector for initiating
a detonation or deflagration in a fuse. The detonation or
deflagration may be propagated from one fuse to another. These
fuses may be low-energy fuses or not. By "low-energy fuse" is
meant a fuse which has such a small explosive effect that it is
not capable of itself propaga-ting a detonation from one fuse to
another.
According to a first aspect of the invention there is
provided a propagating connector which comprises a tubular
member that is hollow to define an elongate blind socket having
its mouth at one end of the member and at its other end a
securing means whereby fuse may be secured to the member.
The securing means may comprise at least one securing
channel into which a straight length of fuse may be clipped to
be secured therein.
According to a second aspect of the invention there
is provided a propagating connector which comprises an elongate
member having at one end at least one securing channel into
which a straight length of fuse may be clipped to be secured
therein.
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The channel may be linear and may have a substan-
tially circular cross-sectional profile. The size of the
channel may be slightly smaller than that of the fuse with
which it is intended to be used. The channel may have an
entrance slot that opens out in a direction away from the
channel, which may be transversely to the axis of the member or
longitudinally with respect thereto. The entrance slot may
taper inwardly. The member may be of any suitable material, in
particular any suitable synthetic plastics material. For
example it may be of polyethylene.
~ s indicated above, the member may have a blind
socket. The closed end of the socket may be adjacent the or
each securing channel and may be separated therefrom by a web.
The closed end of the socket may be shaped to channel a propa-
gating shock wave towards the or each channel.
The connector may be moulded in one piece in a
suitable mould. The invention accordingly extends to a mould
for moulding a propagating connector as defined above, the
mould having suitable complementary moulding formations.
The invention extends to a propagating device which
comprises
a propagating connector according to the invention, that
is hollow to define an elongate blind socket;
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a propogating base charge within the blind socket adjacent
its closed end; and
an end of a length of propagator fuse secured within the blind
socket via its open end~
The base charge may be a pyrotechnic or explosive
composition. It may be a primary explosive material such as
lead azide or a combination of a primary and secondary
explosive material such as a combination of lead azide and
pentaerythritol-tetranitrate (PETN~. It may still further be a
low-strength or high-strength charge.
In regard to the propagator fuse, it may be any one
of a low-energy fuse such as that known as Nonel, an electric
fusehead, a fuse, and a low-energy detonator cord.
It will be appreciated that the use to which the
detonation is propagated, hereinafter referred to as the
propagatee fuse, which is clipped into the securing channel(s)
may be Nonel, detonating cord of charge from 1 g/m to 10 g/m~ or
a pyrotechnic cord.
Those skilled in the art will appreciate that the
propagator fuse may be secured in the connector by any- suitable
means. Thus the propagator fuse may be secured in the connector
via a closure plug and/or a ferrule. The ferrule may extend
the entire length of the member or along only a part thereof.
Where the ferrule extends along a part only of the member, the member
may be`thinner along that part wherealong the ferrule extends.
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The addressee of this specification will further
appreciate that at least one delay element may be interposed
between the free end of the propagator fuse and the base
charge. The or each such delay elements may be single or multi-
cored, rigid and incrementally filled, or drawn. Thus the
propagating device may act instantaneously or may incorporate a
time delay.
The propagating device may be used in a stoping or
tunneling application, particularly with Nonel, either in the
blasting system itself to propagate initiation from one length
of fuse to another or to start initiation thereof. Further,
the propagating device may be used in a noiseless trunkline
application, or to ignite an ignitercord.
Even further according to the invention there is
provided a propagating module which comprises a length of fuse
having at one ena a propagating device in accordance with
the invention.
The length of fuse may have, at its other end, a
detonator.
According to a still further aspect of the invention
there is provided a method of manufacturing a propagating de-
vice, which includes
providing a propagating connector having a blind socket
therein;
inserting propagating base charge material into the
socket; and
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securing an end of a length of propagator fuse into the
socket via its mouth and closing the mouth.
The method may include inserting a delay element into
the socket, between the end of the propagator fuse and the base
charge.
The invention is now described, by way of examples,
with reference to the accompanying drawings, in which:-
Figure 1 shows a longitudinal sectional view of oneembodiment of a propagating connector in accordance with the
invention, and
Figures 2 to 5 show longitudinal sectional views of
various propagating devices in accordance with the invention,
utilising various different connectors.
Referring to Figure 1, shown therein generally by
reference numeral 10 is a propagating connector in accordance
with the invention. The connector 10 is moulded from polyethylene
and, as shown, comprises a tubular èlongate member l2 having
therein a blind socket 14, which has its mouth 16 at one end 18
of the member 12, the member 12 having at its other end 20 a
securing channel 22 into which propagating fuse (not shown) may
be clipped. The channel 22 has a tapered entrance slot 24
which opens out transversely. It will further be noted that
the channel 22 has a circular cross-section, the diameter
thereof being slightly less than the diameter of Nonel tubing
with which it is to be used.
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The blind socket 14 is slightly tapered and at its
blind end is convexed so that a shoc~-wave generated therein is
channelled towards the channel 22. Further, towards its end 18
the member 12 is narrowed, as at 26 to acco~modate a ferrule,
as will be described below with reference to the other Figures.
Referring now to Figure 2, shown therein is a
propagating device 30. The device 30 comprises a connector 32
similar to that shown in Figure 1, except that the channel 22
is oblong so that it may accommodate two propagatee fuses. Within the
blind socket 14 there is a base charge 34 packèd into the blind
socket 14 against its blind end; a delay element 36 and
propagator Nonel 38. The propagator Nonel 38 is held in place
b~ means of a closure plug 40 and a crimped ferrule 42 (crimp
not shown). It will be appreciated, that with the propagating
device 30 if propagatee fuse is clipped into the channel 22 and
the propagator fuse 38 is initiated, the propagator fuse 38
will initiate the base charge 34 after a time interval
determined by the delay element 36 with the base charge 34
initiating the propàgatee fuse.
Referring now to Figure 3, an electric propagating
device is shown, referred to by numeral 50. The propagating device
50 has a connector 52 that has two securing channels 54, having
entrance slots 24 which open out longitudinally. The starter
50 also has base charge 34 and a delay element 36 with an
electric fuse head 56 held in place by means of a closure plug
40 and a crimped ferrule 42.
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Referring now to Fi~ure 4, the propagating device 60
shown therein has a connector 62 similar to that shown in
Figure 1 within which is packed a base charge comprising a
primary explosive material 64 and a secondary explosive
material 66. In this case the propagator fuse is conventional
fuse 68 which is held in place by means of a crimped ferrule
42.
Referring finally to Figure 5, the propagating device
70 shown therein has a connector 72 similar to that shown in
Figure 1 except that the mouth 24 of the channel 22 is axially
directed. This device 70 also has a base charge 34, two delay
elements 36 and propagator fuse 74 in the form of low energy
detonator cord. This propagator fuse 74 is also held in place
by means of a closure plug 40 and a crimped ferrule 42.
As indicated above, the propagating devices may be
used in stoping or development applications, either in the
blasting system itself to propagate initiation from one end of
the blast to another or to start initiation thereof. Further,
the propagating device may be used in a noiseless trunkline
application, or to "start" an ignitercord trunkline.
The propagating devices in accordance with the
invention, at least those illustrated above, have the advantage
that they utilise one-piece connectors into which the elements
of a detonator are directly packed resulting in a simple, cheap
and reliable construction; as the connectors are of plastic, no
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shrapllel i.s generated in use; further, as the connectors are of
an electrically insulating material, the possibility of
detonation due to electrostatic charges is minimised.
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