GB2200977A

GB2200977A - A propagating device for low energy fuses

Info

Publication number: GB2200977A
Application number: GB08801934A
Authority: GB
Inventors: Jean Luc Curutchet
Original assignee: AECI Ltd
Current assignee: AECI Ltd
Priority date: 1987-02-11
Filing date: 1988-01-28
Publication date: 1988-08-17
Anticipated expiration: 2008-01-28
Also published as: CA1316759C; AU599199B2; GB2200977B; GB8801934D0; IE880267L; ZW788A1; NZ223367A; AU1094688A

Abstract

A propagating device, or relay, is provided for interconnecting lengths of low energy transmission fuse to permit propagation of a shock front from one length of low energy fuse to another in either direction. The device comprises a propagating means encased in a housing 12 to which the lengths of fuse 26 are connected. In a preferred form of the device the propagating means comprises two explosive elements 30 with an intermediate pyrotechnic delay element 14; each element 30 comprises lead azide or lead styphnate 34 in an aluminium tube 32. The housing is sealed by membranes 22. <IMAGE>

Description

A PROPAGATING DEVICE FOR LOW ENERGY FUSES THIS INVENTION relates to a propagating device or relay, for low energy fuses and to a blasting system including lengths of low energy fuse interconnected by means of the said propagating device.

According to the invention there is provided a propagating device for low energy fuses which includes a housing; a first connection means fast with the housing for connecting a first length of fuse to the housing so that the said first length cf fuse is in communication with the interior of the housing; a second connection means spaced from the first connection means, the second connection means being fast with the housing for connecting a second length of fuse to the housing so that the said second length of fuse is also in communication with the interior of the housing; and a propagating means located within the housing intermediate the first connection means and the second connection means, the propagating means being responsive to a shock wave passing into the housing from the first length of fuse for providing a propagating shock wave to the second length of fuse of sufficient intensity to activate the second length of fuse.

The housing may comprise a substantially tubular member with the first connection means being provided at one end of the tubular member and the second connection means being provided at the other end.

The propagating means may comprise two propagating elements arranged in spaced relationship within the interior of the tubular member.

Each propagating element may comprise a short length of tubing containing an explosive or pyrotechnic composition. The explosive composition may comprise lead azide, lead styphnate or a mixture of both.

The device may include a delay element arranged intermediate the two propagating elements. The delay element may comprise a pyrotechnic composition.

Each connection means may comprise a component defining a passage whereby communication with the interior of the housing is established. Conveniently, the component may be a plug which is receivable in the end of jhe tubular member.

The passage may be closed off by a membrane to seal the interior of the housing hermetically.

Each connection means may include a spigot-like formation which projects outwardly from the component, the spigot-like formation being engageable with an end of the associated length of fuse. It will be appreciated that, in place of the spigot-like formation, a socket-like portion with which the length of fuse is engageable could be provided.

The device may include a closure member for each spigot-like formation for closing off the free end of each spigot-like formation.

The connection means and the delay element may be retained in position in the housing by the housing being crimped about the connection means and the delay element.

It will be appreciated that with a propagating device fn accordance with the invention, a shock front may be propagated from one length of low energy fuse to another, in either direction, With or without time delay.

The invention also includes a blasting system which includes a plurality of lengths of low energy fuse for connection to explosive chargaswith adjacent lengths of low energy fuse being interconnected by means of the said propagating device.

The invention is now described, by way of an example, with reference to the accompanying drawing, which shows a sectioned view of a propagating device in accordance with the invention.

Referring to the drawing, a propagating device, or relay, is designated generally by reference numeral 10. The device 10 has a tubular housing 12 that is of aluminium, copper or a suitable synthetic plastics material. Centrally located within the housing 12 is a time delay element 14 which is of a suitable pyrotechnic composition, such as Si/PbO . The housing 12 2 is crimped in the region of the time delay 14, as at 16, to retain the delay element 14 in position.

At each end of the housing 12 there is a rubber plug 18 which defines a central passage 20, the passage 20 being closed close to its inner end by means of a membrane 22. The plugs 18 are held in position by crimping of the housing 12, as shown åt 24. Further, in the embodiment illustrated, a short length of tubing 26 which may have some explosive powder therein as is the case with low energy fuse has one end secured within the passage 20 of the plug 18 and has its other end projecting a short distance from the free end of the plug 18. The free end of each length of tubing 26 is closed by a cap 28 It will be appreciated that, instead of the length of tubing 20, the end of the length of fuse could be inserted into the passage 20 of the plug 18 directly.

Between the delay element 14 and the plugs 18, and spaced from the delay element 14, there are two propagating elements 30, one on each side of the delay element 14. Each propagating element 30 constitutes a short length of hollow aluminium 32 which is packed with a suitable propagating material, such as lead azide or lead styphnate 34.

In use, the caps 28 are removed and a first length of low energy fuse -(not shown) is engaged with one length of tubing 26 by means of a connecting piece (also not shown) and the other length of tubing 26 is engaged with the other length of fuse '(also not shown) by a further connecting piece (that is also not shown). Then, a shock wave provided by one of the lengths of fuse will pass through its associated length of tubing 26, rupture the membrane 22 and activate the adjacent propagating element 30. This propagating element 30 will in turn activate the delay element 14. After a period of time determined by the delay element 14 the other propagating element 30 will be activated and it in turn will rupture the membrane 22 adjacent thereto with the shock wave passing through the associated length of tubing 26 into the low energy fuse connected thereto, thereby initiating a shock wave in that length of low energy fuse.

It will be appreciated that more than one length of fuse can be connected to each end of the propagating device 10, by suitably branched connecting pieces.

Claims

1. A propagating device for low energy fuses which includes a housing; a first connection means fast with the housing for connecting a first length of fuse to the housing so that the said first length of fuse is in communication with the interior of the housing; a second connection means spaced from the first connection means, the second connection means being fast with the housing for connecting a second length of fuse to the housing so that the said second length of fuse is also in communication with the interior of the housing; and a propagating means located within the housing intermediate the first connection means and the second connection means, the propagating means being responsive to a shock wave passing into the housing from the first length of fuse for providing a propagating shock wave to the second length of fuse of sufficient intensity to activate the second length of fuse.

2. The device as claimed in Claim 1 in which the housing comprises a substantially tubular member with the first connection means being provided at one end of the tubular member and the second connection means being provided at the other end.

3. The device as claimed in Claim 2 in which the propagating means comprises two propagating elements arranged in spaced relationship within the interior of the tubular member.

4. The device as claimed in Claim 3 in which each propagating element coriprises a short length of tubing containing an explosive or pyrotechnic composition.

5. The device as claimed in Claim 4 in which the explosive composition comprises lead azide, lead styphnate or a mixture of both.

6. The device as claimed in any one of Claims 3 to 5 inclusive which includes a delay element arranged intermediate the'two propagating elements.

7.. The device as claimed in Claim 6 in which the delay element comprises a pyrotechnic composition.

8. The device as claimed in any one of the preceding claims in which each connection means comprises a component defining a passage whereby communication with the interior'of.the housing is established.

9. The device as claimed in Claim 8 in which the passage is closed off by a membrane to seal the interior of the housing hermetically.

10. The device as claimed in Claim 8 or Claim 9 in which each connection means includes a spigot-like formation which projects outwardly from the component, the spigot-like formation being engageable with an end of the associated length of fuse.

11. The device as claimed in Claim 10 which includes a closure member fetr each spigot-like formation for closing off the free end of each spigot-like formation.

12. The device as claimed in any one of Claims 6 to 11 inclusive in which the connection means and the delay element are retained in position in the housing by the housing being crimped about the connection means and the delay element.

13. A propagating device for lengths of low energy fuse substantially as described and as illustrated herein.

14. A blasting system which includes a plurality of lengths of low energy fuse with adjacent lengths of low energy fuse being interconnected by means of a propagating device as claimed in any one of Claims 1 to 13 inclusive.