ZA200603095B

ZA200603095B - Detonator assembly

Info

Publication number: ZA200603095B
Application number: ZA200603095A
Authority: ZA
Inventors: White Michael David Edwards
Original assignee: Za Detnet South Africa Pty Ltd
Priority date: 2003-10-13
Filing date: 2006-04-19
Publication date: 2007-11-28
Also published as: EP1673586A2; CA2542586A1; AR046419A1; WO2005036095A3; AU2004280646A1; PE20050714A1; WO2005036095A2; US20070107617A1; AP2006003607A0

Description

DETONA"TOR ASSEMBLY

BACKCSROUND OF THE INVENTION

[0001] This invention relates generally to a detonator asse=mbly and is also concermed with a method of installineg a plurality of detonatoms in a plurality of respective boreholes.

[0002] it is known to make use of electronic detonators, whi ch are individually prograrmnmable, to establish a blasting «configuration. Each detorator is assigned a unique identity number and is connected in parallel to a trunk< cable. As each detonattor is uniquely identified it is peossible to address a cho:sen detonator and prograrmn desired blasting information inteo the detonator.

[0003] In a different connection technicgue a plurality of detonator—s are connected to one another in a daisy-chain configurat ion. In this arrangement —the detonators are addresssed in sequence with a given det-onator being placed in a programming mode while th-e other detonators are in a norm-programmable mode. C-ertain benefits are associated with a daisy-chain arrangement although one disadvantage arises from the need to make a connection between each detonator in the =sequence and the following and preceding detonators. Th is aspect and the capabilifty of being able to insert a detonator to a variable depth irside a borehole, give rises to a requirement that two variable lengths of cable must toe associated with each detonator viz. a first cable lemngth to go down a first borehole= and a second cable length to go from the first bore=hole to an adjacent, second borehole. In dealing with the cables associated with eac=h of a large number of detonatcors, the cables can becorsne entangled with one anot=her and errors can arise in configuring a blasting sequences.

[O®004] Another aspect which should be addressed is that each detonator should be paackaged in a way which facilitates the use of automated manufacturing and testing processes, which readily allows for handling and transport, and which enables each detonator to be labelled so that it complies wit h applicable regulations and legislation.

S®JMMARY OF INVENTION

[02005] The invention provides a detonator asssembly which includes a first cable coil with first and second ends, a second cab le coil with third and fourth ends, a detonator connected to the first end of the firs-t cable coil, a first connector connected to the second end of the first cable coil and to the third end of the second cable coil, ard a second connector connected to the fosurth end of the second cable coil and wierein a first variable length of cable, externding from the first end, can be drawn from the first cable coil without materially mooving the first connector and a second vamriable length of cable, extending from thea fourth end, can be drawn from the se=cond cable coil without materially moving the= first connector. [0®D06] The first cable coil may be provided in the form of a first tubular roll. The first erid may be inside the first tubular roll. Sirmilarly the second cable coil may be provided in the form of a second tubular roll and the fourth end may be inside the sescond tubular roll.

[0007] The detonator assembly may inclu-de a confinement structure of any appropriate type for maintaining the cable in thee required coiled configuration.

[0008] The first connector may be accessible without opening or~ removing the confinement structure. The first connector may for example be pcasitioned on an outer side of the confinement structure.

[0009] The second and thisd ends of the cables, which are connected to the first connector, are preferably irmtegrally connected and at no time are =separable from each other. These ends mays extend out of the confinement structure.

[0010] The confinement struicture may be in the form of a housing which includes a first compartment for the first cable coil. A second compartment maay be provided inside the housing for the se=cond cable coil. At least one divider may be positioned between the compartmentss. Preferably the first and second cable coils are separated by at least two diwiders. Each divider may be provided in &ny appropriate way and preferably each divider abuts at least one recessed formatiora which extends from an outer surface of the housing into an interior of the housing.

[0011] The confinement structure may be circular cylindrical or in the form of a 156 parallelepiped. In one emb-adiment the confinement structure is in the form of a housing which is made fron a relatively rigid material, and the ho using has four relative large sides and two relatively small sides which form opposeed ends of the housing.

[0012] The housing may be made from any suitable material and mawbe made from a rigid material such as cardboard which may be corrugated or a similar bio- degradable material.

WU1s) Ihe trst awd third ends of the cables may extend through respective apertures in the smaller sides of the housing.

[0014] In a preferread form of the invention the confinement structure is made- from flexible sheet mater-ial. The sheet material may extend around the cable coilss and may have a compossition which allows the sheet material to be shrunk onto the coils.

This type of sheet muaterial is known in the art.

[0015] Each cable coil may be positioned inside a respective enclosure which, in turn, is located ins ide the confinement structure. The enclosure may corrmprise flexible sheet materi al such as plastic film. Each cable coil may comprise a plurality 0 of windings arranged in overlying layers around a hollow core.

[0016] The winding=s may be arranged so that they form a circular cylindrical shape.

The first end may exxtend from an innermost winding of the first cable coil, facin g the respective hollow come. This allows the cable to be withdrawn from the first cable= coil without removing the= first coil from the confinement structure. 5 [0017] The fourth emnd may be similarly configured with respect to the second cable coil. ~ [0018] The inventior also provides a method of forming a cable coil assembly wshich includes the steps of drawing cable from a supply source and winding a single ceoil of a first predetermined length around a first former, severing the cable so that the [ single coil is separatezd at a first end from the supply source, and forming a first c=able coil by winding cable,. of a second predetermined length which is shorter than the= first length, drawn from t he single coil, commencing at the first end, around a second tormer™, and thereby simultaneously formingg a second cable coil of a length which is substantially equal to the difference betwee-n the first and second lengths. [00190 The single coil may be formed by winding the cable in a first direction around the firsst former and the first coil may be ®ormed by winding cable drawn from the single coil in a second direction around the second former, wherein the first direction is opposite to the second direction.

[0020] The first cable coil may be positiomed so that it is co-axial with the se cond cable coil.

[0021] The invention also provides a meth od of installing a plurality of detonators in a respeective plurality of boreholes in a dai=sy~chain configuration which includes the steps, for each borehole, of drawing a firsi length of cable from a first cable caoil in confineement structure, positioning a first destonator which is connected to a first end of the first length of cable at a predetermired depth inside the respective borekole, drawingg a second length of cable from a second cable coil inside the confinerment 5 structumre and connecting a first connector which is at a junction of the first and second coils, at the confinement structure, &o a second connector which is at an end of a respective second length of cable associated with a first borehole.

[0022] The method may include the steep of connecting a respective second connec=tor at an end of the second length of cable, associated with the respective

J “ borehoBe, to a respective first connector at a second borehole,

BRIEF DESCRIPTION OF THE DRAWINGSS

[0023] The invention is further described by way of examples with reference to the accompanying drawings in wsvhich:

Figure 1 schematically depicts a plurality of detonators which are located in respective boreholes and which are connected to each other in a daisy ~chain configuration;

Figure 2 is a cross sectional view of a detonator assembly according to the invention;

Figures 3 and 4 are perspective views of the detonator assembly of Figgure 2 illustrating different aspects -thereof;

Figure 5 is a schematic side= view of a detonator assembly according to the invention with a housing thereof fully opened:

Figures 6 to 8 show the detonator assembly in different stages of manufacture;

Figures 9, 10 and 11 illustrate steps in the winding of cable coils for use in a detonator assembly accordirg to one form of the invention;

Figure 12 is a perspective wiew of a detonator assembly according to a variation of 16 the invention;

Figure 13 is a side view in cross section of the detonator assembly in Figure 12; and

Figure 14 is similar to Figure 1, depicting the use of a plurality of the detonator assemblies in Figure 12, in am blasting system.

DESCRIPTION OF PREFERRED EMBODIMENT

[0024] Figure 1 of the accormpanying drawings illustrates schematically a pluraslity of boreholes 10A, 10B ... 10ON which are drilled in the ground 12 using conven tional techniques. A respective de=tonator 14A, 14B ... 14N is placed in each boreho le. A first length 16A, 16B ... 16 of cable extends from the respective detonator to a respective first connector 18A, 18B ... 18N which is positioned at surface, eand a respective second length 20A, 20B .... 20N of cable extends between adjacent pair-s of connectors 18A and 18B, 18B and 18C, ... 18N — 1 and 18N.

[0025] As indicat ed in the preamble to this specifi cation practical problems arises, when making a dazisy-chain arrangement of the types shown in Figure 1, in that th e lengths 16 and 220 of the cables are variable. If standard lengths of cable are connected, before=hand, to a connector 18 then once a detonator 14 is placed in a borehole a first exxcess portion of cable can lie at tre mouth of the borehole while, once a connectior is made between a connector 18/A\ and a following connector 183, a second excess Rength of cable can lie on the surface between the boreholes. Trae invention is aimed at addressing at least this type of goroblem.

[0026] Figure 2 iBlustrates a detonator assembly 30 according to the invention. Thee assembly includess a cable confinement structure w~hich is formed by a housing 32 which is of parallelepiped form which, as is more cle€arly shown in Figures 3 and =4, has four relatively large rectangular sides and opposed ends 34 and 36 which are smaller than the l=arger rectangular sides. The housimng 32 is made from a corrugate=d cardboard blank 38 generally of the type shown in Fi gure 5 which is formed with lines of weakness and cut-outs so that the blank can Boe folded into the configuration shown in Figures 3 and 4. At three of its longitudltinal corners 40A, 40B and 40-C respectively, portieons of the blank can be forced inw~ardly to form right angled recesss formations 42A, 4-28 and 42C respectively. As is siown in Figure 2 end portions 34 and 46 of the blaank abut these formations, on an inner side of the housing, ard thereby divide tlhe housing interior info three acompartments 50, 52 and 4 respectively.

[0027] Figure 4 illustrates further details of the recessed formation 42CC which extends a substantial portion of the wilidth of the respective side, designatect 56. A relatively large rectangular window 58 is formed in a base of the recessed fo rmation.

A rectangular cardboard insert 60, w=hich has a centrally located relativesly small 5) rectangular window 82, is locatable in tlhe recessed formation 42C.

[0028] Figures 9 to 11 illustrate succe ssive stages in the manufacture of two coils of cable from a single length of cable 66. A large drum 68 of the cable 66 is mo=unted to suitable support structure 70. The c=able 86 is passed over suitable pull eys and rollers 72 and 74 respectively and is w~ound in a first direction 76 about a first former 160 78. A predetermined length of cable, say 40 metres long, is wound onto thee former 78 to form a single coil 80. A first end 82 of the cable is positioned inside ar interior of the coil. Thereafter the coil is sever—ed by means of a set of knives 84. Te cable is then wound onto a second former 86 in a direction 88 which is opposite tc the first direction 76. The cable is drawn from fhe single coil 80 for this purpose. In &his way, 185 as is shown in Figure 11, a first coil _90 is formed with a predetermined | ength of cable of, say, 30 metres and a second coil 82 is formed with a predetermined length of, say, 10 metres. The first coil has &a second end 94 which is integrally connected to an end 96 of the second coil (referre-d to herein as the third end). A free emnd of the coil 92 designated 98, and referred to herein as the fourth end, is positionezd inside 2e0 an interior of the second coil.

[0029] As is shown in Figure 2 the: first and second coils, which are «coaxially aligned, are inserted into the compaartments 50 and 54 respectively. “The end portions 44 and 46, which act as divicders, have slits 99 through which parts of the cable section 100 between the coils (e=ffectively the integrally joined ends 9<% and 96 255 shown in Figure 11) can pass. The acable section 100 is then looped through the window 583, as is shown in Figures 4 and 5. The first end 82 of the first coil is passed through a n aperture 104 in the end 34 of the housing while the fourth end 98 of the second coil is passed through an aperture 106s in the end 36.

[0030] Resferring particularly to Figures 7 and 8 a first connector 110 is crimped onto the cable section 100 without severing this cakole i.e. the first and second coils zare at all times i ntegrally connected to each other. A label 112 is attached to the able adjacent te first connector. A second connec=tor 114 is attached to the fourth emd of the cable. A detonator 116 of conventional cdesign which is suited for daisy-chain connectiors is attached to the first end 82 of th.e cable.

[0031] The end 82 is looped, as is shown in Figures 2 and 8, and the detonator 116 is inserted into the compartment 50 so that it li es inside the hollow interior of thes first coil 90. Tihe fourth end 98 is folded over an external surface of the housing ard is coupled with a press fit to the first connector -110. The cardboard insert 60 is then manipulateed so that the connectors 110 aned 114 pass through the window 62 together with the label 112. The insert is them pushed into the recessed formaation 42C (see Figure 4) so that the connectors are contained within the recesssed formation. Thereafter a preformed tubular sleesve 120, of rectangular cross-section, is placed over the housing to envelope the feour larger sides. The sleeve is pre- printed witfn information which relates to the cletonator and which is prescribed by 0 regulation and legislation. The sleeve has ssiits 122 which define a rectanggular section 1243 which can be folded inwardly to ne :stle in the recessed formation 4283 so that the sleseve is thereby kept in position on the= housing.

[0032] Whaen the detonator assembly is to be used it is transported to a blast site and allocated to a particular borehole 10. A tamb 136 on the sleeve is pulled to ®ear

“the sleeve free from the housing or, alternatively, the sleeve is torn only eno=ugh to expose the connector set. The connectors 110 and 114 are then detacheed from «each other. The detonator 116 is extricated freom the interior of the housing. C able is drawn from the first coil 90 so that the detonamtor can be inserted to a predeterrmined depth inside the borehole. It is pointed out in this respect that the detonateor 116 =shown in Figure 7 corresponds to a detonato r 14 shown in Figure 1. The lergth of scable between the detonator and the housirng 32 is designated by the refesrence #numeral 16 in Figure 1. A predetermined lengsth of cable, corresponding to the length 20 shown in Figure 1, is drawn from the secornd coil. This enables the connector 114 to be connected to a corresponding first connesctor 110 at an adjacent boreholse 14B, =3s is shown in Figure 1.

[0033] As each length of cable 16 and 20 is drawn from the housing the position of fthe first connector 110 is not materially alteered. Excess cable not required for amaking connections between adjacent boreholles is left in the housing. 16 E0034] “By mounting two coils inside the housi ing multiphase manufacturing ste=ps are amade possible. The housing, with its conterits, can be moved or indexed trough sequential automated manufacturing processe=s. The detonator and the conrmectors can be tested while secured within the packaging.

M0035] The outer sleeve is preferably pre-printed with deployment instructiors and 0 ssafety information as may be stipulated by Iccal and international legislation.. The

Ssleeve is kept in position, relatively to the hoeusing, by means of the folded portion ~124 which engages with a corresponding recesss 42B.

[0036] The recessesd formations 42A and 42B facilit=ate handling of the housing for they provide converient handgrips.

[0037] The detonator 116 is preferably stored as is. shown in Figure 2, within the confines of the firs coil 90. This, together with the= partitioned packaging desigrm, provides a substantial amount of separation of deton=ators which are in a plurality coef detonator assemblies. The detonator can be remcaved from the housing without undue handling of tte housing.

[0038] Figures 12 to 14 illustrate a detonator assembely 30A, according to a variatiom of the invention, winich bears substantial similarities to the detonator assembly 30.

Consequently, whewre relevant, like reference numerals are used to designate likes components.

[0039] First and se=cond coaxially aligned coils 90 and 92 respectively, which are slightly spaced frorm each other, are formed using any suitable technique. Eachh cable coil has a plurality of windings 150, 152 arournad a corresponding hollow corse 90A, 92A, and has «a circular cylindrical shape. The cable coils are linked by a cable section 100 to whiech a connector 110 is crimped. An end 82 of the first coil i s connected to a detonator 116 which is positioned inside the hollow core 90A of the first coil. An end 9 8 of the second coil, accessible from the hollow core 92A of thee "second coil, is conrected to a connector 114 which «can be mated to the connector 0 110.

[0040] The coils 90 and 92 are separately wrapped i.n a suitable sheet material, e.g. a cling-wrap plasticc material 160 and 162, and the coils are then held in a fixe-d relationship to eack™ other by means of a confinement structure which comprises a shrink wrappineg 164 which has openings 166 and 168 zat opposed ends of the assembly throLagh which the detonator 106 and the connectors 110 and 114 can respectively be accessed.

[0041] Figure 14 is similar to Figure 1 and depicts a blasti ng arrangement which is established threough the use of a plurality of the detonator eassemblies 30A. For the sake of convernience reference numerals which are the samme as those in Figure 1 are used to dessignate like components.

[0042] The detonator assembly 30A is used in substantially the same way as the detonator asse=mbly 30. The wrapping 164 is cheaper than - the housing 32 and, apart from the acces -s openings 166 and 168, is waterproof.

[0043] In the preceding description the cable coils 90 aand 92 are linked by the integral cable =section 100. Although this is a preferred for-m of construction it is not essential for tke respective end portions of the cable coilss could be interconnected through the us e of a suitable connector 110, which is also cdesigned to engage with a connector 114 _.

[0044] The detonator assembly provides a means of connection between detonators insside the same blast hole or in sequential Iolast holes, by permitting sufficient cable to be withdrawn from the housing. Unuse=d cable remains securely within the paeckaging and the likelihood of cable knots or damage occurring is reduced.

[0045] The inve=ntion has been described with refere-nce to the use of a singles detonator in eaach ‘borehole.

Similar techniques can be employed to makes connections betwseen two or more detonators in a single borehole, if required.

Claims

1. A detonator assesmbly which includes a first cable coil with First and second ends, a second ecable coil with third and fourth ends, a detorator connected to the first end of the first cable coil, a first connector connected to the second end of thhe first cable coil and to the third end of trme second cable coil, and a secord connector connected to the fourth end of tEne second cable coil and whereire a first variable length of cable, extending from the first end, can be drawn from the first cable coil without materially "smoving the first connector and a& second variable length of cable, extending from the fourth end. can be dra=wn from the second cable coil without matewrially moving the first connector.

2. A detonator asssembly according to claim 1 wherein the first cable coil is provided in the f«om of a first tubular roll.

3. A detonator asseembly according to claim 2 wherein the first end is inside the first tubular roll.

4, A detonator asssembly according to any one of claims 1 teo 3 wherein the second cable comil is in the form of a second tubular roll.

5. A detonator asssembly according to claim 4 wherein the fourth end is inside the second tubu lar roll.

6. A detonator asssembly according to any one of claims 1 to 5 wherein each cable coil is at least partly enclosed in sheet material.

7. A detonator assembly accordings to any one of claims 1 to & wherein the cable coils are co-axially aligned =with each other. :

8. A detonator assembly according fo any one of claims 1 to 7 which includes confinement structure for maintaining the cable coils in a desired configuration.

9. A detonator assembly accord ing to claim 8 wherein thes confinement structure is a housing which is made from rigid sheet material.

10. A detonator assembly accorcding to claim 8 wherein thme confinement structure comprises flexible sheeast material. :

11. A detonator assembly according to claim 10 wherein the flexible sheet material is shrunk onto the cablee coils.

12. A detonator according to anwy one of claims 8 to 11 weherein the first connector is accessible without: removing the confinement structure.

13. A detonator according to any one of claims 8 to 12 wherein the confinement structure includes first and seacond compartments for the first and second cable coils respectively.

14. A detonator assembly according to claim 10 or 11 wherein the confinement structure is circular cylindrical.

15. A detonator assembly according to claim 10 or 11 whereim each cable coil comprises a plurality of windings which are arranged irm overlying layers around & hollow core and which form a circular cylindrical shape, with the first end extending from an innermost winding of the first catole coil, and the fourth ed extending from an innermost winding of the seconed cable coil, the detonator assembly including confinement structure around thme cable cails.

16. A detorator assembly which includes first and second cable coils, a detonator which is connected to one end of the first calble coil, a first connector which connects an opposing end of the first cable coil to one end of the second cable coil, a second connector which is connected to an opposing end of the second cable coil, and confinement structure around the firstand second cable coils.

17. A method of forming a cable coil assembly which includes the steps of drawing cable from a supply source and winding a single coil of a first predetermined length around a first former, severing the cable so that the single coil is separated at a first end from the supply source=, and forming a first cable coil by winding cable, of a second predetermined length which is shorter than the first length, drawn from the single coil, commencing at the first end, around a second former, and thereby simultaneously forming a second «able coil of a length which is substantially equal to the difference between the first and second lengths.

18. A metho d according to claim 17 wherein the single coil is for med by winding the cable in a first direction around the first former and the fir st coil is formed by winding cable drawn from the single coil in a second direction around the second Former, wherein the first direction is opposite to the se=cond direction.

WE 2005/036095 17 E> CT/ZA2004/000110

19. A method of installing a pluralitzy of detonators in a respective plurality of boreholes in a daisy-chain confisguration which includess the steps, for each borehole, of drawing a first length of cable from a first cable coil in confinement structure, positionirg a first detonator wh ich is connected to a first end of the first length of ecable at a predetermi ned depth inside the respective borehole, drawing a second length of cable from a second cable coil inside the confinement structure and connecting &a first connector which is at a junction of the first and sexcond coils, at the confinement structure, to a second connector which is at ar end of a respective ssecond length of cable associated with a first borehole.

20. A method according to claim —19 which includes the= step of connecting a respective second connector -at an end of the seacond length of cable, associated with the respective borehole, to a respect ive first connector at a second borehole.