Note: Descriptions are shown in the official language in which they were submitted.
^'` ICIA 1330
1 3~7699
TON~TOR SYSTEM
This invention relates to the blasting o rock
and ore and more particularly to an apparatus for
blasting.
Large-scale bla~ting of rock and ore involving
a large number of explosive chaxges is a ~killed art
in that the size of the charges and the order and
timing of their detonation must be precisely
controlled. The timing of any given detonation is
achieved by a combination of timing of firing signal
and the delay built into the de~onator which
detonates the charge. In the past, the delays have
been pyrotechnic, that is, they comprise a
combustible chemical fuse which on receiving a
firing signal takes a finite time to burn down and
set off the charge. The time scatter inherent in
pyrotechnic delays of the same delay time ha~ meant
an increase in interest ln electronic detonators
where much more precise timing i~ possible~ In
: addition, it is possible to make such detonators
programmable such that the programming and firing
înstructions can be communicated to_the detonator
when it is in place. Thi~ has the ma~or advantages
: 25 that (a) only a single detonator type need be kept
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rather than ~he con~iderable inventory previously
neces~ary, and ~b) tha blast pattern can be set or
changed at any t~me between loading and detonation.
In spite of the ver~atility intrcduced by
programm2ble electronic detonators, thexe remain
.problem~ with large-scale bla~t~. One of these i~
the complexity of the wiring required to communicate
with all of the detonators. One of the most common
ways of comm~nicating firing instructions is by
means of a multi-channel ~xploder ~MC~, a device
which can trigger a number of detonations at
~pecified delays. However~ when the blast pattern
is large, the wiring can become very complex, with
MCEs operating other ~C~s, and it is often very
difficult or even impossible to achieve the
detonation delays and pattern which give the most
efficient use of explo~ive.
We have now found that by using a particular
combination of element~, the previous dif~iculties
of wiring large blast patterns can be substantially
o~ercome. We therefore provide, according
to the present invention, an apparatus ~or blasting,
the apparatus comprising a plurality of detonator~
and an exploder, the individual detonators
having delays which are electronically
pxogrammable and the exploder communicating to
the detonators at least progra ~ing and firing
signal~, the detonators being connected such that
programming signals will be received ~y a given
detonator only when the delay of the ad~acent
detonator nearer to the signal output of the
exploder has been programmed.
We also provide a method of detonating a
plurality of explosive charges in ~ predetermined
pattern and at predetenmi~ed tLme in~ervals, the
charges bein~ detonated by detonators each of which
is individually programmable in respect of delay
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time and each of which received at least its
programmlng and firing ~ignals from ~n exploder
device to ~hich all detonators are connected,
each detonator being connect~d 8uch ~hat
S it will receive prvgramming signal~ only when the
delay of the ad~acent d~tonator nearer to the ~ignal
output of the exploder has been programmed. The
apparatus of our invention permit~ of considerable
versatility in the firing of large bla~t patterns.
In contrast to the methods currently used by the
art and which employ parallel wiring of great
complexity, a ~ingle length of communications wiring
will ~erve the entire pattern. The invention
permits the versatility of programmable detonators
to be fully realised.
The detonators for use in this invention may
be any type of detonator known to the ar~ which are
suitable for u~e in con~unction with electronic
delays. It i8 permissible to include pyrotechnic
delays in the system, but the scatter inherent in
the delay time~ of such delay appreciably reduce~
the precision made possibly by the use of
el~ctronics. We therefore use detonators in which
are incorporated programmable delays, or non-delay
or fixed delay types to which suitable programmable
electronic delay circuitry can be appended. The
power to make the detonators functio~ may be
provided by any con~enient means known to the art,
for example, by batterie~ located within or near the
detonators, by solar cell~ at the surface or by
power sent fxom the exploder and retained in a
capacitor.
The exploder may be any device capable of
sending a serie~ of electronic signals. It may ~e,
for example, a suitably modified microcomputer~ A
preferred exploder comprise~ a keypad for loading
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delay times, a display for verification, ~ securi~y
mechanism for the prevention of unauthorised use and
a means for resetting after an abor~ed flr~ng.
Other features can add considerably to the
S versatility of the sy~tem. For example, ~n one
e~bodiment the keypad is detachable from the
exploder and may b~ directly coupled to the
detonator for the input of information. This can be
done either prior to or after loading the detonator.
The information is stored on a microprocessor
associat~d with the keypad and can ~e passed on to
the exploder when the keypad i~ plu~ged back into
it. The provision of all of these features is well
within ~he skill of the art.
The communications wire which ~oins the
detonator~ and the exploder device may ~e
any suitable wire known to the art to be suitable
for use with electronic detonators. It may be, for
example, a three core wire having a power line, a
communication line and an earth. Another option i8
a two core wire wherein a ~ingle line carries both
communications and power. Individual lengths of
communications wire may be used to ~oin the
individual detonators, but ~t is much easier and
preferable to use a single length of wire (known as
a "bus" wire) to which the detonator can readily be
attached. ~n essential feature of the in~ention is
the connection of the detonators or groups of
detonators such that any given detonator will not
receive delay programmin~ instructions until the
detonator precedin~ it in the series connection,
that i~, the one n~arer to ~he signal output of the
exploder, has receive~ and s~ored its programming
instructionsO Thi~ is achieved by electrical means
which may be ~uilt into or appendable to a detonator,
but which preferably is incorporated into ~ connector
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which ~akes the connection bet~een t~e
det~nator and the ad~ac~nt detonators or the
ad~acent detonator and the exploder. A typ$cal
format will compr~se a swi~ching device, ~uch aR a
relay, which is acted upon by a logic element, the
series connection runn~ng through the ~witchinq
device. Only when a delay t~me h~s been received
and stored will the logic element act to close the
switch and permut the programming signals to reach
the next detonator in line.
The invention will now be further described
by reference to the drawings which depict a
preferred embodiment.
Figure 1 depicts a schematic layout of an
1~ apparatus for blasting according to the invention.
Figure 2 d~picts schemat~cally a connector by
which a detonator i8 linked to an exploder and which
permits the passage of programming signals when a
detonator associated therewith has been programmed.
An exploder 1 has two terminals, 2 and 4,
which are ~oined by a continuous bus wire 3. To
this bus wire are attached detonators 6 b~ means of
connectors 5. ~ connector can service a single
detonator or a qroup of detonators, these being
connected to the connector S and therefore to the
bus wire by connectors 7.
The circuitry of tha connector S is shown in more
detail in Figure 2. The bus wire 3 comprises two
lines, an e~rth wire 8 and a power/communications
30 wire 9. The power/communications wire i~
di~continuous, ~eing broken at the connector and
rerouted through a circuit 10 which comprises a
relay-operated switch 11 and a logic element 12.
Prior to signal receipt the switch is in the ~off"
position; any signals coming along the
power/communiration~ wire will thus stop at this
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point. The logic element 12 is connected to the
power/communications wire on that side of the switch
which receives the incoming signal. It is also
connected to the earth wire, to the detonator by wire
13, and to the switch such that it can change the state
of the relay and close the switch.
In operation, programming signals arrive
from the exploder via the power/communications wire
9 and are prevented from going further b~ the switch
11. The signals are then passed on to the
programmable delay element in the detonator and when
these have been received, stored and verified, the
logic element 12 actuates the relay, closing the
switch and permitting programming signals to pass to
the next detonator. When all programming ignals for
all detonators have been sent, the exploder sends a
final signal which should be received at terminal 4.
If no such signal arrives at 4, or if the exploder
receives a signal out of sequence, an error
condition is lndicated and firing is disabled. If
the final signal is received, firing is enabled and
is brought about by the issuing of "arm" and "fire"
signals. The hardware used in the performance of
this invention i~ ei~her readily available to the
~5 person ~killed in the art, or could be easily
constructed. The connector 5 may be fabricated with
quick-acting, insulation-piercing components which
allow its easy attachment to bus wire~. Other
variations will be obvious to the skilled person. For
example, the detonator may have a fixed delay and a
variable delay may be incorporated into the logic
element of the connector.
The invention permits the use of detonators
with degrees of precision, safety and ease of
installation and use not previously attainable in
commercial blaRting.
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