Ammunition and explosives – Igniting devices and systems
Patent
1987-02-26
1989-08-29
Jordan, Charles T.
Ammunition and explosives
Igniting devices and systems
102215, F42C 1540
Patent
active
048606537
DESCRIPTION:
BRIEF SUMMARY
This invention relates to an actuator to be used with a detonator and to a detonator-actuating system for use in blasting.
BACKGROUND ART
A conventional blasting system comprises a series of explosive charges which are detonated by detonators which are wired to a remote command source. In order to prevent breakage of the wiring connecting detonators set to go off late in the blasting by earlier explosions, the detonators are provided with delays, such that the last detonator to explode has received its firing signal prior to the explosion of the first. Recent improvements in the system have included electronic delays (replacing the older, less precise pyrotechnic delays), and the ability to program such delays in situ. German Offenlegungsschrift 3301251 provides an example of the versatility of which these systems are capable.
There has recently been provided in my copending Australian Patent Application Number PH1255 a detonator which comprises conditioning means which renders fusehead conductors incapable of carrying a voltage or current capable of firing the detonator prior to the altering of the conditioning means from a "normal" (incapable of being fired) state to an "armed" state. This provides a considerable safety factor not previously present in detonators.
DISCLOSURE OF INVENTION
I have now found that it is possible to maximise this safety factor by using such detonators in combination with a particular actuating system. I therefore provide, according to the present invention, an actuator for a detonator, characterised in that the actuator comprises control circuitry which is responsive to input signals from the control device applied to inputs thereof, said control circuitry being operable, on receipt of at least one predetermined input signal, to (i) generate an output arm signal which is applied in use to the detonator and render it capable of being actuated and (ii) generate an output actuate signal which is applied to the detonator after a predetermined delay relative to said predetermined input signals to cause explosive actuation of the detonator.
By "actuator" I mean a unit whose function is to receive signals from a control device, and to actuate a detonator. The type of detonator with which an actuator of the type used in this invention is associated may be one which must be armed before it can be detonated. An especially preferred type is described in my co-pending Australian Patent Application No. PH1255. However, the actuators according to my invention may be used in association with conventional detonators by, for example, connecting the detonator with the actuator such that only the actuate signal is transmitted to the detonator. By "associated", I mean that the detonator and the actuator may be connected in some way such that signals may be passed from actuator to detonator. This may be achieved, for example, by wiring the two components together, or by incorporating the actuator within the detonator. However, in a preferred embodiment, the actuator and detonator are in modular housings, and are simply connected together prior to putting into a blasthole. In this case, all the appropriate electrical connections are made by the connection of the modular housings.
The actuator for use in this invention incorporates the delay which is so important in large-scale commercial blasting. The specific length of delay may be built into the actuator during manufacture, but I prefer to have the delay programmable; this confers considerable versatility on the system. Thus, an actuator may be programmed electronically prior to its being inserted in a blasthole. Even more versatility is conferred by having the actuator programmable when the detonator is in place in the blasthole via the means through which the input signals are transmitted. Thus, a blast pattern can be altered at will and in complete safety up to the time of sending of the input arm and input actuate signals.
The electronic circuitry within the actuator stores delay information and acts on an appropriate signal or appropri
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patent: 4674047 (1987-06-01), Tyler et al.
Deeley S. T.
Jordan Charles T.
Moorhouse D. J.
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