WO2007110826A1

WO2007110826A1 - Detonation of explosives

Info

Publication number: WO2007110826A1
Application number: PCT/IB2007/051032
Authority: WO
Inventors: Michael David Edwards White
Original assignee: Affrican Explosives Limited
Priority date: 2006-03-24
Filing date: 2007-03-23
Publication date: 2007-10-04
Also published as: PE20071302A1; AR060117A1

Abstract

This invention relates to a connector for connecting a detonator having a cylindrical housing containing a base charge at one end thereof, to at least one acceptor shock tube to be initiated by the detonator, the connector including: a body having an open-ended bore or a straight right-cylindrical passage of constant diameter passing therethrough; and at one end of the bore, a clip mounted on the body for clipping at least one acceptor shock tube in place, adjacent and opposed to said end of the bore or the passage. This invention also extends to a method of connecting such a connector to at least one acceptor shock tube.

Description

THIS INVENTION relates, broadly, to the detonation of explosives by means of detonators. More specifically, the invention relates to a connector for connecting a detonator to one or more acceptor shock tubes to be initiated by the detonator, and to a method of connecting such detonator to said one or more shock tubes using the connector.

According to the invention there is provided a connector for connecting a detonator having a cylindrical housing containing a base charge at one end thereof, to at least one acceptor shock tube to be initiated by the detonator, the connector including: a body having an open-ended right-cylindrical passage passing therethrough; and at an inner end of the passage, a clip mounted on the body for clipping at least one acceptor shock tube in place, adjacent and opposed to said inner end of the passage.

The connector may be of plastics construction and may be in the form of a unitary plastics moulding. The body may be elongated, the passage extending from its inner end centrally lengthwise along the body to an outer end of the passage for receiving a chemical detonator inserted into the connector, the inner end of the passage being partially occluded by at least one stop, for example at its periphery, for limiting the depth of insertion of the detonator into the outer end of the passage, to prevent the detonator from protruding from the inner end of the passage, while leaving a central opening in the inner end of the passage which provides a window for permitting a detonation front propagated by the detonator to issue from the inner end of the passage.

The clip may be in the form of a resiliently flexible limb fast with and protruding from the body of the connector to extend transversely to the passage at a position spaced from the inner end of the passage, in the longitudinal direction of the passage, to define a space between the limb and the body, for receiving at least one acceptor shock tube, for example three shock tubes arranged side-by-side, with each acceptor shock tube clipped by the limb in place, opposed to the inner end of the passage, each limb having a root fast with the body and a free end remote from the root. The free end may be resiliently movable away from the body in the longitudinal direction of the passage to enlarge the space to permit insertion of each acceptor shock tube into the space, after which release of the limb permits it resiliently to move back towards the end of the body, to grip and hold each acceptor shock tube in place.

On opposite sides of the passage the body may be provided respectively with two gripping panels, the panels respectively defining two oppositely transversely outwardly facing gripping surfaces for facilitating gripping and manipulation of the connector by a user, for example between the thumb and forefinger, the gripping surfaces optionally being ribbed by respective series of spaced ribs, the ribs acting further to facilitate gripping and manipulation of the connector by a user. This facilitates insertion of a detonator housing into the open end of the passage (and/or its removal therefrom). The gripping panels may extend, substantially fully, along the body lengthwise relative to the passage, the body and the panels being elongated in shape, and the panels having a width no less than the outer diameter of the body, the limb of the clip being formed by an extension of one of the gripping panels, the extension having substantially the same width as said panel, the window at the inner end of the passage being directed at the axially inner surface of the limb of the clip.

More particularly, the gripping panels may be fast with the cylindrical body along central parts of their radially inner faces, the panels being curved about axes parallel to their ribs, respectively to provide curved saddles or indentations therein for receiving the thumb and forefinger of a user, the connector being strengthened by webs interconnecting the gripping panels and connecting them to the outer surface of the cylindrical body.

The invention extends to a method of connecting a detonator having a cylindrical housing containing a base charge at one end thereof and having its other end provided with initiation means, to at least one acceptor shock tube, the method including the steps of: clipping each acceptor shock tube to a connector as described and defined above by means of the clip of the connector, with each acceptor shock tube in a position opposed to the open inner end of the passage, with the open end directed at each acceptor shock tube; and and inserting the detonator into the outer end of the passage so that part of the detonator is held in the passage with a frictional fit, the end of the detonator containing the base charge being inserted into the passage first and being located at or adjacent each acceptor shock tube, the detonator projecting from the outer end of the passage.

The method may include the step of clipping a plurality of acceptor shock tubes, side-by-side, in said position opposed to the open inner end of the passage.

Either the acceptor shock tubes can be connected first to the connector, followed by the detonator, or vice versa.

Naturally, a connector and detonator will be selected and employed wherein the bore or passage is matched in diameter with the outer diameter of the housing of the detonator, to provide a suitably tight said frictional fit. When the inner end of the passage has one or more stops, as described above, insertion of the detonator into the passage is facilitated, the inserted end being pushed up against the one or more stops, to ensure that the spacing between the base charge in said inserted end and the acceptor shock tubes is appropriate. The invention will now be described, by way of non-limiting illustrative example, with reference to the accompanying diagrammatic drawings, in which:

Figure 1 shows a schematic end elevation of a connector according to the invention;

Figure 2 shows a schematic end elevation of the opposite end of the connector of Figure 1 ;

Figure 3 and 4 show schematic side elevations of opposite sides of the connector of Figure 1 ;

Figure 5 shows another schematic side elevation of the connector of Figure 1 , rotated by 90° relative to Figures 3 and 4;

Figures 6 and 7 show schematic three-dimensional views of the connector of Figure 1 ; and

Figure 8 shows a more or less axially sectioned schematic three- dimensional view of the connector of Figure 1 on an enlarged scale, after connection thereof to a detonator housing.

In the drawings a connector in accordance with the invention is generally designated by reference numeral 10. The connector 10 is a unitary or monolithic plastics moulding, being injection moulded from polypropylene (in other examples similar materials can be used). The connector 10 has an elongated right-cylindrical hollow body 12 provided with a central right-cylindrical passage 14, in the shape of a bore, passing therethrough and opening out of opposite ends of the body 12, namely an outer end 16 and an inner end 18. The inner end of the passage 14 is partially occluded by four stops 20 (omitted from Figure 8 for ease of illustration but see Figure 2) which are peripherally located straight-edged ribs projecting radially inwardly somewhat from the periphery of the inner end 18, being arranged end-to-end to define a more or less square window 22 there (Figure 2). The stops 20 are for limiting the depth of insertion of a detonator into the outer end of the passage 14, to prevent the detonator from protruding from the inner end of the passage 14.

The body 12 is provided on opposite sides thereof respectively with two gripping panels 24, 26 fast therewith, the panels 24, 26 respectively presenting transversely oppositely outwardly facing gripping surfaces 28 (Figure 5), which carry ribs 30 extending normally to the passage 14, each surface 28 having a series of ribs 30 spaced side-by-side, for facilitating gripping and manipulation of the connector 10 by a user, particularly during insertion of a detonator into the passage 14. The panels 24, 26 extend along the full length of the body 12 and are elongated, having a width slightly greater than the outer diameter of the body 12. The panels 24, 26 are fast via their inner surfaces at central positions along their lengths, midway between their side edges, with the curved outer surface of the body 12, the connector 10 being strengthened by various webs 32 extending between the panels 24, 26 and between said panels 24, 26 and the body 12. The panels 24, 26 are somewhat curved about axes parallel to the ribs 30 to provide indentations 33 (Figure 5) respectively for receiving a user's thumb and forefinger.

The panel 24 has an extension which forms a limb 34 extending from a root 35 at the end of the panel 24 adjacent the inner end of the passage 14, to a free end 36, the limb 34 being of more or less the same width as the panel 24 and extending across and over the inner end of the body 12, where it faces the window 22 at the inner end of the passage 14. The limb 34 of the clip is spaced, in the longitudinal direction of the passage 14, from the inner end of the passage 14. The limb 34 is resiliently flexible and can be pivoted about its root 35 in the longitudinal direction of the passage 14, away from or towards the inner end of the body 12, to permit insertion therein of up to three acceptor shock tubes 38 (Figure 8), a space 40 being defined between the limb 34 and the adjacent or inner end of the body 12, the space 40 having an inwardly tapered mouth or entrance at 42, tapering in a direction transverse to the passage 14, the mouth or entrance 42 being located at the free end 36 of the limb 34, opposite the root 35, between said free end 36 and the inner end 18 of the body 12. The shock tubes 38 are located side-by-side in opposition to the window 22. In Figure 8 the end of a housing 44 of a chemical detonator is shown inserted into the passage 14, up against the stops 20 (not shown in Figure 8 but see Figure 2) defining the window 22. The housing 44 is of aluminium and is the housing of a chemical detonator initiated by a signal shock tube (not shown) inserted into the end of the housing 44 opposite the end inserted into the passage14, the inserted end of the housing 44 intruding in the passage 14 and abutting the stops 20. The inserted end of the housing 44 contains a base charge (not shown) suitably closely located relative to the acceptor shock tubes 38 for initiation of the shock tubes 38 by detonation of the base charge in the housing 44.

In use the limb 34 simply has its free end 36 resiliently pivoted away from the body 12 in the axial direction of the passage 14, to pivot the limb 34 away from the body 12, to enlarge the space 40, to permit the acceptor shock tubes 38 to be inserted, in a direction transverse to the shock tubes 38 and transverse to the body 12, into the space 40 via the entrance 42 and in the direction of taper of the entrance 42, after which the limb 34 is released and is allowed resiliently to return towards its normal position, so that it can resiliently grip the acceptor shock tubes 38 in place, opposite the window 22 and with the window 22 directed at them. The detonator housing 44 in turn, before or after the clipping in place of the acceptor shock tubes 38, is simply inserted into the outer end 16 of the passage 14 until its inserted end abuts the stops 20 at the window 22 at the inner end 18 of the passage 14, in which passage 14 it is held with a frictional fit, with the detonator projecting from the outer end of the passage. Insertion of the acceptor shock tubes 38 into the space 40 is carried out manually by a user, who conveniently grips the connector 10 via its ribbed surfaces 28. The detonator housing 44 is however expected to be inserted into the passage 14 with a press fit by a machine forming part of an assembly line.

Claims

1. A connector for connecting a detonator, having a cylindrical housing containing a base charge at one end thereof, to at least one acceptor shock tube to be initiated by the detonator, the connector including: a body having an open-ended right cylindrical passage passing therethrough; and at an inner end of the passage, a clip mounted on the body for clipping at least one acceptor shock tube in place, adjacent and opposed to said inner end of the passage.

2. A connector according to claim 1 wherein the connector is in the form of a unitary plastics moulding.

3. A connector according to claim 1 or claim 2 wherein the body is elongated, and the passage extends from its inner end centrally lengthwise along the body to an outer end of the passage for receiving a chemical detonator inserted into the connector, the inner end of the passage being partially occluded by at least one stop for limiting the depth of insertion of the detonator into the outer end of the passage, to prevent the detonator from protruding from the inner end of the passage, while leaving a central opening in the inner end of the passage which provides a window for permitting a detonation front propagated by the detonator to issue from the inner end of the passage.

4. A connector according to any one of claims 1 - 3 wherein the clip is in the form of a resiliently flexible limb fast with and protruding from the body of the connector to extend transversely to the passage at a position spaced from the inner end of the passage, in the longitudinal direction of the passage, to define a space, between the limb and the body, for receiving at least one acceptor shock tube with each acceptor shock tube clipped by the limb in place, opposed to the inner end of the passage, each limb having a root fast with the body and a free end remote from the root.

5. A connector according to claim 4 wherein the free end of the limb is resiliently movable away from the end of the body, in the longitudinal direction of the passage, to enlarge the space to permit insertion of each acceptor shock tube into the space, after which release of the limb permits it resiliently to move back towards the end of the body, to grip and hold each acceptor shock tube in place.

6. A connector according to any preceding claim wherein, on opposite sides of the passage, the body is provided respectively with two gripping panels, the panels respectively defining two oppositely transversely outwardly facing gripping surfaces for facilitating gripping and manipulation of the connector by a user.

7. A connector according to claim 6 wherein the gripping surfaces are ribbed by respective series of spaced ribs, the ribs acting further to facilitate gripping and manipulation of the connector by a user.

8. A connector according to claim 6 or claim 7 wherein the gripping panels extend, substantially fully, along the body, lengthwise relative to the passage, the body and the panels being elongated in shape, and the panels having a width no less than the outer diameter of the body, the limb of the clip being formed by an extension of one of the gripping panels, the extension having substantially the same width as said panel, the window at the inner end of the passage being directed at the axially inner surface of the limb of the clip.

9. A method of connecting a detonator having a cylindrical housing containing a base charge at one end thereof and having its other end provided with initiation means, to at least one acceptor shock tube, the method including the steps of: clipping each acceptor shock tube to a connector as claimed in any one of claims 1 - 8 by means of the clip of the connector, with each acceptor shock tube in a position opposed to the open inner end of the passage, with the open end directed at each acceptor shock tube; and inserting the detonator into the outer end of the passage so that part of the detonator is held in the passage with a frictional fit, the end of the detonator containing the base charge being inserted into the passage first and being located at or adjacent each acceptor shock tube, the detonator projecting from the outer end of the passage.

10. A method according to claim 9 which includes the step of clipping a plurality of acceptor shock tubes, side-by-side, in said position opposed to the open inner end of the passage.