INTERCONNECTING LOW ENERGY FUSES

Abstract: A connector 100 for interconnecting two lengths of low energy fuse 108, 110 includes connecting means 101 having a needle-like portion 102. The needle-like portion 102 is pointed at both ends 104, 106 to facilitate the pen­ etration of the ends 104, 106 into the lengths of fuse 108 and 110 respectively. The connector 100 further includes a body 112 which defines seats 114 on which regions of the lengths of fuse 108, 110 can seat to be retained in posi­ tion relative to the connecting means 101. End caps 116 are provided to clip into the body 112 to retain the lengths of fuse 108, 110 on the seats 114.

Description: THIS INVENTION relates to the interconnecting of low energy fuses, in particular low energy fuses such as that known by the trademark "NONEL". Low energy fuses of this type comprise plastics tubing containing a suitable explosive material. According to one aspect of the invention, there is provided a connector for interconnecting at least two lengths of low energy fuse of the type described, for transferring a shock wave front of an explosion propagating along one length of fuse to the other length of fuse which includes a hollow tubular connecting means which defines a passage and which is insertable into the lengths of fuse so that the interior of a first length of fuse is in flow communication with the interior of a second length of fuse via the passage of the connecting means; and a retaining means for retaining the connecting means in position relative to the lengths of fuse. It will be appreciated that two or more lengths of fuse may be interconnected. Thus, the connecting means may have two or more end portions, dependent on the number of lengths of tubing that are to be interconnected. The connecting means may include at least one needle-like portion having a pointed end for piercing a wall of at least one of the lengths of fuse. In one embodiment of the invention, the needle-like portion may have a second end remote from the pointed end, which second end is fast with the retaining means, the pointed end of the needle-like portion being insertable through the walls of the two lengths of fuse when the lengths of fuse are arranged adjacent one another with their longitudinal axes parallel to one another. In another embodiment of the invention the needle-like portion may have a second end that is also pointed, so that one of the pointed ends of the needle-­ like portion is insertable through the wall of one of the lengths of fuse and the other pointed end of the needle-like portion is insertable through the wall of the other length of fuse, the lengths of fuse being spaced from each other, in use. The passage of the connecting means, may, if desired, contain a primary and/or a secondary explosive. The passage may also contain a pyrotechnic delay The retaining means may comprise a body defining at least one seat in which a connecting region of at least one of the lengths of fuse is receivable for securely retaining the connecting means in position relative to the length of fuse. The retaining means may further comprise at least one end cap which is releasably engageable with the body. In one form of the connector a chamber may be defined in the body and the needle-like portion of the connecting means may comprise two hollow elements, each having a pointed end and each projecting from the chamber, the pointed end of one element projecting out of the seat defined by the body and the pointed end of the other element projecting out of another seat defined by the body. The lengths of fuse may be interconnected with one another intermediate their ends. Instead, the end of one length of fuse may be interconnected with another length of fuse intermediate its ends, in a "T"-­ configuration. With this arrangement, one end portion of a connecting means that is received within an end of the fuse will be co-linear therewith and the other end portion of the connecting means will be inserted into the other length of fuse in a transverse manner. Further, if two lengths of fuse are to be interconnected with one another intermediate their ends then the end portions of the connecting means will be transversely located with respect to the lengths of fuse. It will also be understood that two lengths of fuse may be interconnected intermediate their ends with the lengths of fuse being either parallel, or transverse. Those skilled in the art will appreciate that there will not be any problem in inserting an end portion of the connecting means into an end of the fuse. However, if the end portion of the connecting means is to be inserted into the length of fuse intermediate its ends then the end portion must pass through a wall of the fuse so that an opening into the end portion is located within the length of fuse. This may be accomplished by either first forming a hole in the wall of the fuse and then inserting the end portion, or by adapting the end portion so that it forms a hole as it is inserted through the wall of the fuse. The pointed end of the connecting means may provide an angled opening, the angled opening facing in a suitable direction. Thus, it may face transversely with respect to the length of fuse or longitudinally. The invention is now described, by way of examples, with reference to the accompanying drawings, in which:- Figure 1 shows a schematic sectioned view of two lengths of fuse interconnected intermediate their ends by means of a connector in accordance with a first embodiment of the invention; Figure 2 shows a sectional side view of the connector taken along line II-II in Figure 1; Figure 3 shows a sectional end view of the connector taken along line III-III in Figure 1; Figure 4 shows schematically how two lengths of fuse are interconnected in a "T"-configuration, in accordance with another embodiment of the invention. Figure 5 shows a sectional side view of a connector in accordance with a further embodiment of the invention; Figure 6 shows a sectional side view of yet another embodiment of a connector in accordance with the invention: and Figure 7 shows a sectional side elevation of still a further embodiment of a connector in accordance with the invention. Referring to Figures 1 to 3, a connector in accordance with the invention for connecting at least two lengths of low energy fuse for transferring a shock wave front of an explosion propagating along one length of fuse to the other length of fuse is designated generally by the reference numeral 10. The connector 10 is used for interconnecting two lengths of fuse 12 and 14. Each fuse 12, 14 comprises a length of tubing 16 having its inner walls coated with an explosive powder to form a low energy fuse such as that known by the trade mark "NONEL". The connector 10 comprises a hollow tubular connecting means 18 which is pointed at both ends 20 and 22. Secured to the connecting means 18 intermediate its ends is a collar 24 made of a plastics material. The collar 24 has abutment shoulders 26 on each side. Secured to the collar 24 and extending past and around the pointed ends 20 and 22 are two clips 28 and 30 which are formed integrally with the collar 24. The clips 28 and 30 together with the abutment shoulders 26 of the collar 24 define seats 32 for securely retaining the length of tubing 16 in position relative to the connecting means 18. The clips 28 and 30 are made of a suitably resilient material so that they can be bent back, the fuses 12 and 14 can be engaged with the ends 20 and 22 of the connecting means 18 so that the ends 20 and 22 pierce the tubing 16 of the fuses 12 and 14 respectively to extend into the tubing 16. The clips 28 and 30 can then be released to engage with the tubing 16 of the fuses 12 and 14 to secure them to the connecting means 18. Referring now to Figure 4 another embodiment of the invention is shown. In this embodiment of the invention, two lengths of fuse 40 and 42 are inter­ connected by means of a connector 44 which comprises a short length of metal tube. As shown, the lengths of tubing 40 and 42 are interconnected in a "T"-config­ uration with one end of the tube 44 longitudinally engaging an end of the fuse 40 and the other end portion of the tube 44 being inserted through a wall of the length of fuse 44 intermediate its ends in a transverse manner. The connector 44 includes an outwardly extending flange 45 defining a shoulder against which the end of the length of fuse 40 can abut. Referring now to Figure 5 yet another embodiment of the invention is shown. In this embodiment of the invention, a connector in accordance with the invention is designated generally by the reference numeral 50. The connector 50 comprises a connecting means 51 having a needle-like portion which is constituted by two elements 52 and 54, each having a pointed end portion 56 and 58 respectively. The elements 52 and 54 project parallel to each other from a chamber 60. The chamber 60 is defined by a body 62 of a retaining means 64. The chamber 60 contains a primary and/or a secondary explosive and, if desired, can also contain a pyrotechnic delay. The body 62 defines seats 66 within which regions of lengths of fuse 68 and 70 of the type described can seat. The lengths of fuse 68 and 70 are retained in position on the seats 66 of the body 62 by means of an end cap 72 which engages the body portion 62 and is clipped into position. Referring to Figure 6 yet a further embodiment of a connector in accordance with the invention is shown, the connector being designated generally by reference numeral 80. In this embodiment, the connector comprises a hollow tubular connecting means 82 having a needle-like portion 84. The needle-like portion 84 has a pointed end 86 for piercing the walls of two lengths of fuse 88 and 90 which lie adjacent one another so that their longitudinal axes are parallel to each other. The needle-like portion 84 includes a second end 92 remote from the pointed end 86. The second end 92 is fast with a retaining means 94 of the connector 80. The connecting means 82 defines a passage 96 so that the interior of the length of fuse 88 is in flow communi­ cation with the interior of the length of fuse 90 when the needle-like portion has been inserted through the lengths of fuse 88 and 90. Referring now to Figure 7, still a further embodiment of the invention is shown, the connector being designated generally by the reference numeral 100. The connector 100 comprises a connecting means 101 having a needle-like portion 102. Both ends 104 and 106 of the needle-like portion 102 are pointed to facilitate the penetration of the connecting means 101 into two lengths of fuse 108 and 110 respectively. The connector 100 further includes a retaining means in the form of a body 112 which defines seats 114 on which the lengths of fuses 108 and 110 can seat. The ends 104 and 106 of the needle-like portion 102 project from the seats 114. The connector 100 further includes end caps 116 which clip into the body 112 to retain the lengths of fuses 108 and 110 in position relative to the needle-like portion 102. Typically, the connecting means of the various embodiments described above can have an outside diameter of about 1 mm and a length ranging from about 15 mm to 25 mm. The angle of the pointed end of the connecting means of the various embodiments should be about 45° and ideally, should face towards an oncoming shock wave front of an explosion propagating down a length of fuse. By means of the invention low energy fuses may be interconnected in a simple, effective and reliable manner.

Claims: 1. A connector for interconnecting at least two lengths (12,14,40,42,68,70,88,90,108,110) of low energy fuse of the type described, for transferring a shock wave front of an explosion propagating along one length of fuse to the other length of fuse which includes a hollow tubular connecting means (18,44,51,82,101) which defines a passage and which is insertable into the lengths of fuse so that the interior of a first length of fuse is in flow communication with the interior of a second length of fuse via the passage of the connecting means; and a retaining means (24,28,30,64,72,94,112,116) for retaining the connecting means in position relative to the lengths of fuse. 2. A connector as claimed in Claim 1, characterized in that the passage of said connecting means contains a primary and/or a secondary explosive. 3. A connector as claimed in Claim 2 characterized in that the said passage contains a pyrotechnic delay. 4. A connector as claimed in any of the preceding claims characterized in that the connecting means includes at least one needle-like portion (20,22,56,58,84,102) having a pointed end for piercing a wall of at least one of the lengths of fuse. 5. A connector as claimed in Claim 4, characterized in that the needle-like portion has a second end (92) remote from the pointed end (86), which second end is fast with the retaining means (94), the pointed end of the needle-like portion being insertable through the walls of the two lengths of fuse (88,90) when the lengths of fuse are arranged adjacent one another with their longitudinal axes parallel to one another. 6. A connector as claimed in Claim 4, characterized in that the needle-like portion (18,102) has a second end that is also pointed, so that one of the pointed ends (20,22,104, 106) of the needle-like portion is insertable through the wall of one of the lengths of fuse and the other pointed end of the needle-like portion is insertable through the wall of the other length of fuse, the lengths of fuse being spaced from each other, in use. 7. A connector as claimed in any one of Claims 4 to 6 inclusive in which the retaining means comprises a body (24,62,112) defining at least one seat (66,114) in which a connecting region of at least one of the lengths of fuse is receivable for securely retaining the connecting means in position relative to the length of fuse. 8. A connector as claimed in Claim 7, characterized in that the retaining means further comprises at least one end cap (72,116) which is releasably engageable with the body. 9. A connector as claimed in Claim 7 or Claim 8 characterized in that a chamber (60) is defined in the body and the needle-like portion of the connecting means comprises two hollow elements (52,54) each having a pointed end (56,58) and each projecting from the chamber, the pointed end of one element projecting out of the seat (66) defined by the body and the pointed end of the other element projecting out of another seat (66) defined by the body. 10. A method of transferring a shock wave front of an explosion propagating along a first length of low energy fuse to a second length of low energy fuse which includes Interconnecting the respective lengths of fuse by means of a hollow tubular connecting means (18,44,51,82,101) defining a passage, so that the shock wave front can propagate through the passage of the connecting means into the second length of fuse.

Inventors: CURUTCHET, JEAN LUC, FENSHAM, WAYNE GUY
Applicants: AECI LIMITED
Application year: 1986
Main classification: F42D1
IPC codes: F42D1