CA2163694A1

CA2163694A1 - Blowmoulded cartridge

Info

Publication number: CA2163694A1
Application number: CA 2163694
Authority: CA
Inventors: Francis William Bodell; Brent Patrick Corrigan
Original assignee: ATK Blowmoulding Inc
Current assignee: ATK Blowmoulding Inc
Priority date: 1995-11-24
Filing date: 1995-11-24
Publication date: 1997-05-25

Abstract

An explosives cartridge is manufactured as a blowmoulded tubular shell having formed in the exterior surface thereof one or more integral cylindrical wells adapted to receive and securely retch a corresponding detonator.

Description

BLOWMOULDED CARTRIDGE
BACKGROUND OF INVENTION
(a) Fleld of Inventlon This invention relates to a new or improved blowmoulded cartridge for use in holding an exploslve compound and a detonator.
(b) Description of the Prior Art It is known to provide blowmoulded cartridges in the form of tubular plastic contalners to be filled with explosive compounds. In one known cartridge the tubular contalner is formed with external screwthreads ad~acent its opposite ends so that it can be linked to simllar cartridges through the use of a tubular threaded connector sleeve whereby a series of explosive cartrldges of a length requlred ln a partlcular blasting application can readily be put together. One of the cartrldges is closed at one end by a plastlc cap formed wlth a palr of lntegral axlally extending tubular wells to receive detonators, the tubular wells ln the assembled condltlon of the cartrldge extendlng lnto the exploslve compound whlch fllls the lnterior of the cartrldge. Great difficulty has been experienced in establlshlng a satlsfactory seal between the detonator-carrying cap and the open end of the associated cartridge so that in practice problems are encountered with leakage of water into the explosive compound in the lnterior of the cartridge, or alternatlvely leakage of the explosive compound to the exterlor of the cartridge.
SUMMARY OF THE INVENTION
The present invention provides a tubular cartrldge for carrying an explosive compound, said cartridge comprising ~l63691 a tubular contalner having a first end that is sealed by an integral end wall and an opposite circular open end adapted to be sealed by a clrcular closure after the cartrldge has been fllled wlth exploslve compound, sald cartrldge having in an external surface thereof a well that is configured to recelve and retaln a detonator.
The well preferably comprlses a cylindrically formed recess extending axially of the cartridge and opening towards the first end thereof, the recess being formed ln the cartrldge wall ln an lntegral blowmouldlng step. The well ls preferably axially extendlng and part cyllndrlcal ln form belng arranged ad~acent the surface of the tubular contalner and open to the exterlor by a narrow slot of a wldth less than the dlameter of the well so that a detonator placed ln the well cannot be removed ln the radlal dlrectlon.
The open second end can be sealed, after the cartrldge has been fllled wlth exploslve compound, by spln weldlng a clrcular cap onto the annular thln-walled open end of the cartrldge. The exploslve compound ls thus lntegrally sealed wlthln the lnterlor of the cartrldge and there ls no risk of water seepage or escape of exploslve compound.
As before, ln use cartrldges can be lnterconnected by screwthreaded sleeves engaglng the ends of ad~acent cartridges. A detonator can be placed in any one of a series of interconnected cartridges, and the cartridges include grooves on thelr external surface through whlch detonator wlrlng can be led.
BRIEF DESCRIPTION OF THE DRAWINGS
The lnventlon wlll further be descrlbed, by way of .
example only, with reference to the accompanylng drawlngs whereln:
Figure 1 ls an elevatlonal vlew of an exploslve cartrldge ln accordance wlth the present invention;
Flgure 2 ls an enlarged end vlew of the cartrldge taken from the left hand end of Flgure l; and Figure 3 is an enlarged fragmentary sectlonal vlew taken on the llne 3-3 ln Flgure 2.
BRIEF DESCRIPTION OF THE PREFERRED EMBODIMENT
The exploslve cartrldge 10 shown ln Flgure 1 comprlses a sealed lmpervlous tubular contalner closed at one end by an lntegrally formed end wall 11, and closed at the opposite end by a circular cap 12. The tubular container ls formed by a blowmouldlng technique from a sultable plastlcs material such as polyethylene, polyvinylchlorlde, polypropy-lene or any blow grade co-polymer etc. and has a central cyllndrlcal sectlon 13 bounded at opposlte ends by annular grooves 14 and having a number of axially extending grooves 15 on the outer slde thereof.
Ad~acent the closed end 11 the cartrldge has a cylindrical sectlon 16 of reduced dlameter that ls formed wlth an external screwthread 17 whlch ls lnterrupted near lts lnboard end by a detent 18.
Integrally moulded at diametrically opposed locations ln the cyllndrlcal wall of the threaded end sectlons 16 are a pair of cylindrical wells 19, each well having a cylindrlcally formed wall extendlng through at least 200 of arc and belng open to the exterlor through an axlally extending slot 20 which is of a constant wldth that ls ~lG369 4 substantlally less than the internal diameter of the well 19.
The opposlte end 22 of the well ls closed, and of course the lnterlor of the cartrldge ls completely sealed from the wells 19. Each well ls of a length to accommodate any common commerclally avallable detonator which typlcally are ln the range 2 to 3 lnches ln length and opens at lts end ad~acent the end 11 ln an angled surface 21.
The opposlte end of the cartrldge llkewlse comprlses a cylindrical end sectlon 24 of the same dlameter as the cyllndrlcal end 16 and formed wlth an ldentlcal screwthread 25 whlch llkewlse has a detent 26 ad~acent the lnboard end thereof.
The cartrldge 10 ls produced by manufacturlng the tubular shell (wlthout the closure 12) as a blowmouldlng, the wells 19 belng formed around axlally extendlng plns ln the mould whlch can be retracted to allow extractlon of the moulded shell from the mould dles whlch have a partlng llne in a diametral plane of the tubular sleeve.
The tubular sleeve ls then fllled with the deslred exploslve compound (not shown) whereafter the closure cap 12 ls sealed to the open cyllndrlcal end of the tubular sleeve by spin welding so that the lnterlor of the completed cartrldge ls hermetlcally sealed from the exterlor and there ls no danger of leakage ln elther dlrectlon.
In use, a strlng of exploslve cartrldges 10 are lnterconnected successlvely axlally through the use of lnternally threaded tubular sleeves (not shown) whlch have an outer dlameter correspondlng to that of the tubular sectlon 13 and whlch llkewlse are formed wlth thread detents comple-2l6369~

mentary to detents 18 and 19 so that when the threaded sleevels completely engaged wlth the cartrldge threads 17 or 25, the lnteractlng detents engage to retaln the thread agalnst accldental dlsengagement. It wlll be appreclated that when the cartrldges are lnterconnected ln thls way, the tubular connector wlll enclose the well 19 completely, and therefore shleld and prevent accldental wlthdrawal of a detonator (not shown~ placed ln one of the wells.
Instead of blowmouldlng, the cartrldge contalner could be formed by ln~ectlon mouldlng, or by any other sultable process.

Claims

1. A tubular cartridge for carrying an explosive compound, said cartridge comprising a tubular container having a first end that is sealed by an integral end wall and an opposite circular open end adapted to be sealed by a circular closure after the cartridge has been filled with explosive compound, said cartridge having in an external surface thereof a well that is configured to receive and retain a detonator.

2. A cartridge as claimed in claim 1 wherein said well comprises a cylindrically formed recess that extends axially in the wall of the tubular container and opens towards said first end of the cartridge.

3. A cartridge as claimed in claim 2 wherein said well is defined by a cylindrically curved wall integral with the wall of said tubular container, said cylindrically curved wall extending through at least about 200° of arc and being open to the outside through an axially extending slot of predetermined width, said well being designed to receive a detonator having a thickness substantially greater than said width.

4. A cartridge as claimed in claim 1 including integral external screwthreaded formations adjacent both ends thereof, said screwthreaded formations being adapted for engagement by complementary internal screwthreads in a tubular connector through which a pair of such cartridges can be interconnected in axial alignment, said well having an open end at a location where it will be enclosed by such tubular connector in the interconnected condition of said cartridge.

5. A cartridge as claimed in claim 2 fabricated as a blowmoulded plastics article, said cartridge having at opposite ends thereof integral external screwthreaded formations and also having on the external surface thereof recessed grooves through which detonator wiring can be led.

6. A cartridge as claimed in claim 3 fabricated as a blowmoulded plastics article, said cartridge having at opposite ends thereof screwthreaded formations for engagement by complementary screwthreaded formations of a tubular connector sleeve through which two such cartridges can be interconnected in axial alignment.

7. A cartridge as claimed in claim 2 wherein there are two such wells, said cartridge including external grooves to receive wiring for detonators placed in said wells.

8. An explosive cartridge comprising a tubular cartridge as claimed in claim 1, the interior of said container being filled with an explosive compound, and the open second end of the container being sealed by a closure spin-welded to the circular edge of the opposite end of said container.