WO2014199355A1

WO2014199355A1 - Shock tube blasting

Info

Publication number: WO2014199355A1
Application number: PCT/IB2014/062213
Authority: WO
Inventors: Glen Leslie Parker
Original assignee: Glen Leslie Parker
Priority date: 2013-06-13
Filing date: 2014-06-13
Publication date: 2014-12-18
Also published as: AP2016008983A0

Abstract

The invention provides a shock tube connector block (1) comprising a hollow body providing an enclosure (6) affording transmission or propagation of a shock wave from a shock tube inlet (4) mounting to multiple shock tube outlet (5) mountings arranged to support a plurality of ends of outgoing shock tubes in suitable proximity to a bare end of an incoming shock tube. The mountings (4, 5) are provided in passages for respective tubes and each mounting (4, 5) includes an outwardly facing shoulder for location of an inner end of a shock tube (14), non-return tube securing means, and a shock tube (14) engaging watertight seal (16). The body is preferably produced in two halves (2, 3) from a single mould with a seal circumferential to the enclosure locatable therebetween and ultrasonically welded together. The invention extends to an associated method of providing a manifold branch in a shock tube (14), which comprises supporting a bare end of an incoming shock tube (14) in an enclosed body in dose proximity to ends of a plurality of outgoing shock tubes (14).

Description

SHOCK TUBE BLASTING

FIELD OF THE INVENTION This invention relates to shock tube blasting equipment and the use thereof; particularly, in a multiple branch, reticulation for detonation of a number of blast hole charges.

BACKGROUND TO THE INVENTION

The use of shock tube in blasting operations for ore recovery is well known as is the use of shock tube connector blocks incorporating a detonator for the distribution of an ignition impulse to a number tubes leading to charges of explosives.

These existing shock tube connector blocks usually comprise of a moulded plastic body into which is inserted the end of an "incoming" shock tube fitted with a detonator. The detonator is held in position by locking members moulded into a bore in the plastic body. On the opposite end of the plastic body it is possible to manually insert "outgoing" additional lengths of shock tube so as to multiply the number of lengths of shock tube, thus creating a step-up branch. Resilient retaining means in the form of a curved clip is usually provided adjacent the blast end of the detonator. One side of the clip forms a mouth. The outgoing shock tubes are inserted under the clip and supported side by side over the end of the detonator.

These step-up arrangements of the shock tubes are provided to suit the required number of explosives used for a single particular blasting operation. The shock (or percussive) wave created by the explosion of the detonator will transmit to the explosive material lining the outgoing shock tubes which will transmit to the following detonator which may again be contained within a connector block, or the explosive charge effecting the blasting operation. In this manner a single ignition system may be split, by the use of detonators contained within connector blocks, to permutations of explosive charges. OBJECT OF THE INVENTION

It is the object of the present invention to provide an apparatus and method which avoids the use of a detonator in the transfer of a shock wave in shock tube connections. The apparatus is simple to install and more cost effective than the kind referred to above.

SUMMARY OF THE INVENTION

In accordance with the invention there is provided a shock tube connector block comprising a hollow body providing an enclosure affording transmission of a shock wave from a shock tube inlet mounting to multiple shock tube outlet mountings.

The invention further provides for a connector as defined: in which the outlet mountings are arranged to support a plurality of ends of outgoing shock tubes in suitable proximity to a bare end of an incoming shock tube, within the enclosure; in which the shock tube mountings are provided in passages for respective tubes; and in which each mounting includes an outwardly facing shoulder for location of an inner end of a shock tube. Further features of the invention provide for a connector as defined: in which each mounting includes tube securing means; in which the tube securing means are each provided by a plate having a tube receiving aperture with a toothed periphery; in which teeth about the periphery of the aperture are inclined into the passage of the mounting in a funneled configuration; in which the plates are of suitably thin steel or alloy that affords resilient flexing to the teeth; in which free inner ends of the teeth are located on a diameter smaller than that of the shock tube with which the connector is to be used and the periphery of the aperture of a greater diameter than the shock tube; in which the plate of a securing means is shaped to engage in a retaining groove provided by the body across the passage; and in which the plate is provided as a strip which extends across all the passages with an aperture located in each passage.

Further features of the invention provide for a connector as defined: in which the mountings each include a shock tube engaging seal provided in the passages; in which the seal is resiliently deformable with an opening sized to sealingly engage around a length of shock tube; and in which the seal is provided by a moulded band which is circumferentially located around the enclosure in a groove provided by the body with a shock tube opening located in each passage. Further features of the invention provide for a connector as defined: in which the body is produced as two halves, moulded from suitable plastics material and secured together with a seal circumferential to the enclosure located therebetween; in which each half is moulded from a single mould with mating faces provided as mirror images; and in which the two halves of the body are ultrasonically welded together. Further features of the invention provide for a connector as defined includes plugs securable into outlet mountings that are not required.

In accordance with another aspect of the invention there is provided a method of providing a manifold branch in a shock tube which comprises supporting a bare end of an incoming shock tube in an enclosed body in close proximity to ends of a plurality of outgoing shock tubes.

Further features of the invention provide for a method as defined in which the incoming and outgoing shock tubes are threaded through uni-directional tube securing means in passages for respective tubes which feed into the enclosure.

BRIEF DESCRIPTION OF THE INVENTION

These and other features of the invention will become apparent from the following description of one embodiment described below with reference to the accompanying drawings in which shows an exploded perspective view of a shock tube block according to the invention;

shows a plan view of one half of the block body;

shows the view of Figure 2 with components of the shock tube mounting fitted to the block and schematic inclusion of four lengths of shock tube; and

shows a perspective view of block half of Figure 3.

DETAILED DESCRIPTION OF THE INVENTION

Referring to the drawings, a shock tube block (1 ) is moulded from suitable plastics material such as polypropylene. The block (1 ) illustrated is suited for use with shock tube having an external diameter of about 3 mm. Other tubing will be used when required and the block will be suitably modified.

The block (1 ) is made hollow and in two halves (2) and (3). Internally the block has an inlet passage (4) and, in this embodiment, four outlet passages (5). (The selection of the inlet passage may be varied with the remaining four passages then serving as outlet passages.) The two halves (2) and (3) are assembled , with the additional components referred to below, to form the hollow body connector block (1 ) providing an enclosure (6).

The enclosure (6) includes a shock tube inlet mounting [in the inlet passage (4)] affording transmission of a shock wave to a multiple shock tube outlet mountings [in the outlet passages (5)]. The transmission is bridged between the bare ends of the tubes through the configuration of the enclosure (6) having the outlet mountings supporting a plurality of ends of outgoing shock tubes in suitable proximity and arrangement relative to the bare end of an incoming shock tube.

A transverse groove (9) formed across the passages (4; 5) is configured to receive thin, generally rectangular strip of stainless steel plate (10). (The plate may also be made from brass or other suitable material.) The single plate (10) provides five uni-directional tube securing means (1 1 ), which greatly facilitates the assembly of a shock tube block (1 ). The plate (10) is bent in two places to provide a symmetrical channel-shape (when viewed in plan). The web of the channel provides three securing means (1 1 ) and each flange a single securing means (1 1 ). The groove (9) is of a corresponding shape.

The plate (10) accordingly includes five circular openings (12), the periphery of which are notched to form a series of teeth (13). (A separate plate with a single opening could be used for each passage but without the same convenient assembly.) The teeth (13) are pressed slightly inwardly to provide a domed or curved funnel formation towards the enclosure (6) into the block (1 ) for non-return engagement onto a shock tube (14), as illustrated in Figures 3 and 4. The shock tube mountings are provided with an outwardly facing shoulder (15) on a protrusion formed to the inside of each passage (4; 5). The size of the apertures (12) are such that 3 mm external diameter plastic tubing (14) can be forcibly threaded past the teeth (13). However, the teeth (13) have inner ends located on a diameter smaller than that of the shock tube (14). On insertion, the teeth (13) are flexed inwardly as the tube (14) is threaded into the passages (4; 5) but will engage the plastic material and prevent subsequent withdrawal of the tubes (14) from the block (1 ). The shock tubes (14) are properly inserted when their inner ends abut against the shoulders (15) of the mountings inside the passages (4; 5).

In addition to securing means (1 1 ), the mountings include a shock tube engaging seal (16) provided in each of the passages (4; 5). The seal (16) is resiliently deformable (and made of any suitable rubber or elastomeric material) with an opening (17) sized to sealingly engage around a length of shock tube (14).

In the illustrated embodiment, the seal (16) is provided by a moulded band or gasket which is circumferentially located around the enclosure (6). A shock tube opening (17) provided through the band (16) is located in each passage (4; 5).

A second, continuous groove (18) provided by the two halves (2; 3) of the body (1 ) receives the seal (16), which not only seals around each shock tube (14) but also across the join between the two halves of the body. The band (16) has a width that is slightly oversized and requires compression when the two halves (2; 3) are assembled. The faces (19) on the edges of the seal (16) sealingly engage in this manner against the opposite ends (or bottoms) of the groove (18).

The openings (17) of the seal (16) have a chamfered leading edge indicated at (17.1 ) in Figure 1 . The ends of the teeth (13) are located inside this region of the openings (17) when the block (1 ) is assembled. This overlapping relationship can be seen in Figure 4. The material of the seal (16) at the openings (17) resists over-flexing of the teeth (13) and its resilience acts as a closing spring around the funnel-shape of the teeth (13).

The plate (10) locates against an inner wall (7) of the groove (9), which is spaced apart from an opposite, outer wall. The inner wall (7) is provided with sufficiently large openings (7.1 ) in the region of the teeth (13). The teeth (13) extend through these openings (7.1 ) [which afford the required flexing space] for location adjacent to and interaction with the seal (16) as referred to above.

Each of the passages (4; 5) includes a guide (8) which extends from the outer wall of transverse groove (9) towards the inner wall (7). The guide (8) is inclined away from the outer wall towards the bottom of the groove (9). A shoulder (8.1 ) is provided on the guide (8) adjacent the bottom of the groove (9). The shoulder (8.1 ) is oppositely disposed to the inner wall (7) and a space between the shoulder (8.1 ) and the inner wall provided as a close fit to the plate (10). The shoulders accordingly hold the plate against the inner wall and prevent outward flexing of the plate if any inserted shock tubes are pulled.

The two halves (2) and (3) of the body are produced by a single mould and then ultrasonically welded together with the plate (10) and seal (16) located across the passages (4) and (5). The configuration of mould provides two identical parts (2; 3) for engagement with mating faces [the formations providing the enclosure (6) grooves (10) and (18), and shoulders (15) are provided as mirror images].

In this manner, two removable plugs (20) are also provided on a single block (1 ). This number of plugs (20) with four outgoing passages (5) allows the block (1 ) to be used to provide a "one into two" branch. Suspension hooks (21 ) are also integrally moulded onto the two halves (2; 3) to facilitate the setting up of a desired blast pattern with blocks (1 ) supported off the ground. In underground mining operations, these hooks (21 ) would allow for easy suspension of the blocks (1 ) above, what is usually, a wet footwall.

The mouldings of two halves (2; 3) further include oppositely disposed, complementary engaging formations provided in the form of a socket (22) and spigot (23) and a rib (24) which runs in two parts between the two halves. The rib (24) provides an energy director for the ultrasonic welding operation and the spigots (23) fit into the sockets (22) for alignment.

It is expected that a configuration providing four outgoing passages will be well suited to the needs of the industry. Where more than four branches are required, two or more blocks (1 ) will be used. The second or subsequent block will be fitted to branch an outgoing tube from the first block to provide a step-up of "one into seven" and so on.

It will thus be appreciated that the provision of two detachable plugs (20) enables the number of branch ignition paths to be restricted without the necessity for special shock tube blocks.

The components of the shock tube block (1 ) illustrated are designed for fully automated assembly. To this end, the single strip plate (10) is provided to fit into the correspondingly shaped groove (10) with the securing means (1 1 ) properly positioned across the passages (4; 5). A single seal (16) services each passage and also provides a waterproof gasket around the enclosure (6) sealing between the two halve (2; 3) of the body. Also, the groove (9) for the plate (10) is made oversize for easy insertion and with the five guides (associated with each passage respectively) that facilitate location of the plate (10) into the bottom of the groove (9) and against the inner wall. The bent shape of the plate ensures that teeth (13) are always correctly oriented, facing into the passages (4; 5). The blocks (1 ) are used to split an initial blast ignition source into several branches which in turn may themselves be split in a further shock tube block (1 ) to give as wide an arrangement of blasts to be ignited very nearly simultaneously as the particular operation requires.

The dusting of suitable explosive powder between the concentric walls of an incoming shock tube (14) has been found to transfer to the material in the array of outgoing tubes (to be connected to detonators in blast holes) without the use of additional detonators along the blast ignition paths. The invention accordingly provides for the propagation of a shock wave from the plain end of an incoming shock tube to those of outgoing shock tubes.

It will be understood that variations may be made to the shock tube blocks described without departing from the scope of the invention.

The tube securing means (1 1 ) of the passages (4; 5) may be provided in any of a variety of forms. The outside edge of the plates could be round or rounded. The apertures in the plates need not be round. A "Y" or "H" shaped slot, for example, would also provide teeth or gripping formations which can be provided with suitably shaped gripping edges and similarly be pressed or deformed inwardly. A suitably sized hole punched into the centre of the teeth formations (to provide gripping edges) in such a slot would facilitate use with a tube.

Claims

1. A shock tube connector block comprising a hollow body providing an enclosure affording transmission of a shock wave from a shock tube inlet mounting to multiple shock tube outlet mountings.

2. A connector as claimed in claim 1 in which the outlet mountings are arranged to support a plurality of ends of outgoing shock tubes in suitable proximity to a bare end of an incoming shock tube, within the enclosure.

3. A connector as claimed in claim 2 in which the shock tube mountings are provided in passages for respective tubes.

4. A connector as claimed in claim 2 or claim 3 in which each mounting includes an outwardly facing shoulder for location of an inner end of a shock tube.

5. A connector as claimed in claim 3 or claim 4 in which each mounting includes tube securing means.

6. A connector as claimed in claim 5 in which the tube securing means are each provided by a plate having a tube receiving aperture with a toothed periphery.

7. A connector as claimed in claim 6 in which teeth about the periphery of the aperture are inclined into the passage of the mounting in a funneled configuration.

8. A connector as claimed in claim 7 in which the plates are of suitably thin steel or alloy that affords resilient flexing to the teeth.

9. A connector as claimed in claim 7 or claim 8 in which free inner ends of the teeth are located on a diameter smaller than that of the shock tube with which the connector is to be used and the periphery of the aperture of a greater diameter than the shock tube.

10. A connector as claimed in any one of claims 6 to 9 in which the plate of a securing means is shaped to engage in a retaining groove provided by the body across the passage.

1 1 . A connector as claimed in any one of claims 6 to 10 in which the plate is provided as a strip which extends across all the passages with an aperture located in each passage.

12. A connector as claimed in any one of claims 2 to 9 in which the mountings each include a shock tube engaging seal provided in the passages.

13. A connector as claimed in claim 12 in which the seal is resiliently deformable with an opening sized to sealingly engage around a length of shock tube

14. A connector as claimed in claim 13 in which the seal is provided by a moulded band which is circumferentially located around the enclosure in a groove provided by the body with a shock tube opening located in each passage.

15. A connector as claimed in any of the preceding claims in which the body is produced as two halves, moulded from suitable plastics material and secured together with a seal circumferential to the enclosure located therebetween.

16. A connector as claimed in claim 15 in which each half is moulded from a single mould with mating faces provided as mirror images.

17. A connector as claimed in claim 15 or claim 16 in which the two halves of the body are ultrasonically welded together.

18. A connector as claimed in any one of the preceding claims which includes plugs securable into outlet mountings that are not required.

19. A method of providing a manifold branch in a shock tube which comprises supporting a bare end of an incoming shock tube in an enclosed body in close proximity to ends of a plurality of outgoing shock tubes.

20. A method as claimed in claim 19 in which the incoming and outgoing shock tubes are threaded through uni-directional tube securing means in passages for respective tubes which feed into the enclosure.