WIRELESS INITIATING ARRANGEMENT

A wireless detonator initiating arrangement (10) which includes a first housing (20) which contains a receiver (24) and a signal processor (28), a second housing (36) which contains an explosive (38), a casing (52) which contains an initiator (16) which is responsive to the signal processor (28) to ignite the explosive (38) and a third housing (46) which contains a power source (50) to power the signal processor (28).

BACKGROUND OF THE INVENTION

This invention relates to a wireless detonator initiating arrangement.

An arrangement of the aforementioned kind can be a bulky device. The arrangement requires a receiver which can receive electromagnetic command signals which travel, at times, through rock. An electrical supply is called for to power the receiver. Provision must be made for a processor to implement command signals relating to synchronisation and firing. An initiator, which may be in the form of a suitably configured detonator, is also required. Electrical energy is needed to ignite the initiator.

Certain applications also call for the initiating arrangement to be coupled in an effective manner to a booster which contains a secondary explosive.

To address the challenges relating to storage and transport a modular approach may be required so that hazardous components can be separated from non-hazardous components. This aspect mitigates against assembly of the initiating arrangement under factory conditions and, conversely, means that assembly on site by an operator, at a blast bench, should be readily effected in a safe and efficient way.

An object of the invention is to address the aforementioned requirement.

SUMMARY OF THE INVENTION

The invention provides a wireless detonator initiating arrangement which includes a first module comprising a first housing in which is mounted a signal processing assembly, a second module comprising a second housing which is engaged with the first housing and which contains an explosive material, and an initiator which is engageable with at least the first housing.

Preferably the initiator extends between the first housing and the second housing.

The initiator may include a first end which is located in a first recess in the first housing and a second end which is located in a second recess in the second housing.

A power supply may be mounted to the first housing.

In a variation of the invention the wireless detonator initiating arrangement includes a third housing which contains a power supply and which is engageable with the first housing or with the second housing thereby to connect the power supply to the signal processing assembly.

The signal processing assembly, responsive to a wireless fire command signal from a blast controller, is used to cause ignition of the initiator.

The signal processing assembly and the power supply can be in separate interengageable housings. An explosive (booster) can be in a separate housing exposed to the initiator which, optionally, is mounted inside a suitably-designed casing.

The wireless detonator initiating arrangement can be configured to be responsive to magnetic waves which are transmitted through rock to the signal processing assembly. Alternatively, the arrangement is configured to communicate with a top-box, located at a mouth of a borehole in which the arrangement is suspended. The top-box controls operation of the arrangement in response to wireless command signals from a blast controller.

DESCRIPTION OF PREFERRED EMBODIMENT

FIG.1of the accompanying drawings depicts a wireless detonator initiating arrangement10, according to the invention, in a disassembled configuration.

The arrangement10includes a first module12, a second module14and an initiator16.

Referring in addition toFIG.4the first module12comprises a first elongate tubular housing20in which is mounted a signal processing assembly22. The assembly22includes an electromagnetic communication signal receiver24which is coupled to a receiving antenna26and a signal processor28. The housing20has a first recess30concentrically positioned at an end32.

The second module14comprises a second housing36which is of elongate tubular shape. The housing36contains a secondary explosive38. The module14constitutes a booster.

The housing36has a second recess40which is concentrically positioned at an end42which faces the first recess30.

An end44of the housing20which is remote from the recess30can be coupled when required to a third housing46which contains a power source50e.g. a battery.

The initiator16has a first end16A and an opposed second end16B.

The initiator16and the second module14which houses the explosive38are hazardous goods. If these components are not connected to the first module12nor to the third housing46then the first module12and the third housing are not regarded as hazardous goods and can be transported and stored without taking into account regulations which apply to hazardous goods. Optionally the initiator16is mounted inside a custom-designed casing52, which is shown in dotted outline inFIG.4.

In one form of the invention the third housing46is coupled to the first housing20under factory conditions. To achieve this use is made of a simple screw fitting to fix the third housing46to the first housing20. A switch54mounted to the housing20is used to prevent the power source50from inadvertently energising the receiver24and the processor28. Prior to installation and use at a blast bench the switch54is turned to an on position so that the power source50can energise the receiver24and the processor28. When the housing46is coupled to the housing20electrical connections are made between contacts56connected to the power source50and contacts58connected to the processing assembly22but through the switch54.

In another form of the invention the third housing46, with the power source50, is connected on site to the housing36, on a side60remote from the initiator16, as is shown by a dotted line80. This can be done by means of a screw fitting, or a bayonet connection. The contacts56on the power source50are thereby connected to contacts84on the housing36. A conductor86, connected to the contacts84, extends to additional contacts88on the housing36. When the housing36is coupled to the housing20the contacts88are electrically connected to contacts90on the housing20and power is then available via a conductor92to operate the receiver24and the processor28, which regulate firing of the initiator16.

In one embodiment of the invention the third housing46with the power source50is supplied as a separate component which is connected to the first housing20, only when required, on site. Use can be made of the switch54to prevent the application of electricity to the receiver and processor until required. The switch54could be electronically controlled in that it is only operable when a signal from an external source, such as a blast controller104, is received by the receiver. Thereafter, the receiver24and the processor28, using energy harvesting techniques which recover energy from a signal, from the blast controller104, induced into coils (not shown) at the receiver24, actuate the switch54and the power source50is then fully connected to the first module12.

On site the assembly process of the initiating arrangement10follows the sequence shown inFIGS.1,2and3.

The end16A of the initiator is configured to be inserted precisely into the recess30of the housing20. An electrical connection is thereby made between terminals96connected to the processor28and operative electrical terminals98in the initiator16. The second end16B of the initiator16is configured to be inserted tightly into the recess40in the housing36. As the recesses30and40are concentrically located, they oppose each other, and the first housing20can then be engaged with the second housing36with a screw action as is depicted inFIG.3.

The housing36, at one end, includes one or more formations100which can be used to lower the assembled wireless initiating arrangement10shown inFIG.3, suspended from a suitable cord, into a borehole (not shown) to a desired position. Prior thereto, if the switch54is not electrically actuable, as described hereinbefore, the switch54is manually operated to provide power to the arrangement10.

In use of the initiating arrangement10(seeFIG.4) a wireless command signal sent from a blast controller104, which is at a remote location relative to the arrangement10, is received at the antenna26and passed to the receiver24. Communication of this type is possible through the use of magnetic waves of a suitable amplitude and frequency which can reliably pass through a body of rock, which is not too sizeable, without undue attenuation. The processor28implements, in a known manner, any instruction contained in the command signal. As noted, if the switch54is electrically actuated a first signal which preferably is encoded would cause the switch54to be closed.

As is known in the art the initiating arrangement is usually first brought into synchronism with other similar initiating arrangements in a blast system. Thereafter, when a fire command is received by the receiver24, the processor28, after a predetermined timing interval previously programmed into the processor, transmits a fire signal106to the initiator16which causes ignition thereof. That in turn causes ignition of the explosive38.

Power for the sequence of operations is derived from the power source50which energises the receiver24and the processor28. Energy from the power source50can be stored in one or more capacitors108in the initiator16or in the processor28or in the initiator and in the processor. This enables a firing sequence to be executed automatically and independently of the power source50once a fire signal has been received by the receiver e.g. a programmed timing delay is processed and, thereafter, the detonator is ignited. This is an important feature for explosive shock waves, generated by other, previously fired, initiating arrangements could interfere with the supply of energy from the power source to the processor and to the initiator.

The modular approach of the initiating arrangement10carries with it the significant advantages referred to hereinbefore, namely that assembly of the arrangement10on site at a blast bench is readily effected as the components are easily connected to one another. These components can only be connected in the manner shown; any attempt to connect the components to one another in a different manner would be unsuccessful.

The initiating arrangement10allows for use to be made of a substantially standard detonator in the initiator16. The initiator16and the second module14are kept separate from the first module12and the power supply50until such time as on-site assembly is required. This feature facilitates storage and transport requirements.

In the preceding description reference is made to a system in which the arrangement10is positioned in a borehole and magnetically-based signals are sent, possibly through rock, to the receiver24.

In a different system the arrangement10is suspended in a borehole from conductors110which are connected to a top-box112positioned, for example, at a mouth of the borehole. The top-box112can communicate wirelessly with a blast controller, and via the conductors110with the arrangement10, to control the blasting process.

When the modules are physically connected to one another, e.g. by means of a screw action or a bayonet fitting, electrical connections are made as contacts on the respective housings are brought together. These contacts can, for example, be spring-loaded to ensure secure electrical connections are made. Other connecting techniques can however be used as may be appropriate.