NZ208080A

NZ208080A - Connector between detonating cord and low energy impulse propagating tubing

Info

Publication number: NZ208080A
Application number: NZ208080A
Authority: NZ
Inventors: T L Love; J Hedger
Original assignee: Ici Australia Ltd
Priority date: 1983-05-20
Filing date: 1984-05-07
Publication date: 1986-10-08
Also published as: NO841994L; GB2140137B; GB2140137A; GB8412265D0; NO161312B

Description

2 08 080 Priority Date(s):. . ..........

Complete Specification Filed: Class: £?.(?&/.&(..., J''''".""" K 6" OCT* 19 86 Publication Date: P.O. Journal, No:-... /r?. .

No.: Date: NEW ZEALAND PATENTS ACT, 1953 COMPLETE SPECIFICATION CONNECTORS f) V JE/ We, ICI AUSTRALIA LIMITED a company incorporated under the laws of the State of Victoria, of 1 Nicholson Street, Melbourne, Victoria 3001, Australia l) hereby declare the invention for which i / we pray that a patent may be granted to^fKK/us, and the method by which it is to be performed, to be particularly described in and by the following statement: - . 1 _ (followed by page la) \<X- ~ "COMMDCTORO' 2 08080 The present invention relates to connectors for explosive blasting operations and is particularly concerned with connectors between detonating cord and low energy impulse propagating tubing. 5 Low energy impulse propagating tubing is replacing the use of detonating cord in certain applications where the noise of detonating cord is unacceptable or the use of detonating cord is hazardous. Low energy impulse propagating tubing is exemplified by 'Nonel' 10 tubing ('Nonel1 is a Registered Trade Mark) manufactured by Nitro Nobel AB.

Up to now it has been impossible to link up explosive charges with low energy impulse propagating tubing in the same way as with detonating cord. 15 Any attempt to do this with known connectors has resulted in an unreliable propagation of the initiation at junctions of more than one initiation path.

The lack of reliable connectors has meant that normal blasting layouts using low energy impulse 20 propagating tubing as the surface trunkline has been sequential with no duplication of initiation pathway, hence any failure of propagation or initiation of a pathway due to any cause will stop further initiation along that pathway. By contrast using detonating cord 25 surface trunkline duplication of initiation pathways is normal.

We have now found a simple connector which is able to be used in both series and in parallel to allow several low energy impulse propagating tubes to be connected 30 to a length of detonating cord and hence form a reliable junction for multi initiation paths. 2 03080 j if pS We provide a connector comprising a plastics housing Diyk«, for a detonator having an open ended detonator tube, V 7>P and means for the open end of a length of low energy impulse propagating tube to be placed adjacent to or inserted into the open end of a detonator tube in a moisture proof seal and wherein the plastics housing has a means adapted to allow a length of detonating cord to be held abutting the closed end of the detonator tube and substantially normal to the axis of the detonator 10 tube.

The means adopted to allow the detonating cord to be held abutting the detonator may be any suitable means for example a clip moulded into the plastic* housing. We have found a particularly convenient means 15 is to provide the plastics housing with an apperture through the housing and substantially normal to the axis of the tube.

Preferably the low energy impulse propagating tube is sealed into the plastics housing coaxial to the detonator tube. The nature of the plastic*material used in the plastics housing is not critical. Preferably the plastics material is thermoplastic to allow economic manufacture by injection moulding. Suitable plastics are for example LDPE, LLDPE, HDPE, PVC P.P., Surlyn 25 and polyamide. (Surlyn is a Registered Trade Mark for a polyolefine).

The end of the low energy impulse propagating tube should not be placed into the detonator tube so far that the end of the tube touches the explosive charge 30 or the delay element in the detonator. The moisture proof seal between the propagating tube and the housing may be made in any convenient way. Thus for example fl / when the propagating tube is placed adjacent to the Pb end of the detonator tube the plastics housing may be «35 crimped around the propagating tube to form a moisture proof seal. 2 0808 Alternatively when the propagating tube is placed just within the detonator tube the detonator tube may be crimped onto the propagating tube prior to insertion into the plastics housing. This can form a water proof seal.

The detonator may be either instantaneous or of the delay type. Connectors fitted with instantaneous detonators will initiate either way. (From low energy impulse propagating tube to detonating cord or vice versa).

The strength of the detonator is not narrowly critical and depends upon the type of detonating cord being used. We have found for normal 10 grain per metre detonating cord that a number 3 detonator is suitable. However different cords may need either a stronger or weaker detonator.

Examples of our invention are shown in the drawings where Fig. 1 shows a sketch of the connection Figs. 3 and 5 are sections along the line A-A of the connector of Fig. 1 Figs. 2 and 4 are sections of an alternative connector.

The plastics housing (1) has a 'Nonel' tube (2) either inserted into the detonator tube (Fig. 2 and 4) or alternatively placed in the plastics housing abutting the detonator tube. (figs. 3 and 5).

) In Figs. 2 and 4 the propagating tube is attached to the -dPtomfltnic- via a waterproof, anti-static closure system comprising the detonator tube an alumimium rivet (3), a conducting plug (4) a free space (5) and a crimp. Both diagrams show a charge of primary explosive; lead azide (6) and Fig. 4 shows a delay element (7) Figs. 3 and 5 show an alternative closure system comprising a modified plastics connector (1) an external aluminium ferrule with a crimp and an increased free space (5).

Claims

- 4 - 2 08 0 80 / (/ M-iu ulaiiuu J<=j£ininy Lliu iitVLiiLiuii aie ds fulluwb; WHAT >/WE CLAIM IS:

1. A connector comprising a plastics housing for a detonator having an open ended detonator tube and means for the open end of a length of low energy impulse 5 propagating tube to be placed adjacent to or inserted into the open end of the detonator tube in a moisture proof seal and wherein the plastics housing has a means /0 Lj adapted to allow a length of detonating cord, to be VV^qJnl^eld abutting the closed end of the detonator tube and lo")^ substantially normal to the axis of the detonator tube.

2. A connector according to claim 1 wherein the low energy impulse propagating tube is sealed into the plasties housing co-axial to the detonator tube.

3. A method of use of the connector to form a 15 layout having dual initiation pathways for explosive charges. 7^S)AY OF ^ DATED THIS I '' "DAY OF ' A. J. PARK & SON PER v AGENTS FOR THE APPLICANTS 19^ DATED Lfa£g= Tidy 1984. TCT Anr.TWAT.TA T.TMTTnD I i,-7MYI98Cj