GB2173285A - A device for projecting and priming an exploding charge laid underground - Google Patents

Abstract

In an extended range mine of the anti-personnel type, comprising an igniter 2 acting on a projection charge 26 in a casing 17 to be laid underground, and a casing 19, containing main charge 20 and splinters 21, which is ejected by the projecting charge, all of the most sensitive or dangerous elements can be taken out in a single operation. Accordingly a cartridge element 24 which can be taken out comprises detonators 14 and 25 for priming respectively the projection charge 26 and the main charge 20, as well as the projecting charge 26. In operation the gases from charge 26 act on container 19 via conduit 28 and space 23. At a predetermined height a pull string 34 attached to container 17 releases striker 30 to activate detonator 25 and hence auxiliary charge 29 and main charge 20. <IMAGE>

Description

SPECIFICATION A device for projecting and priming an exploding charge laid underground This invention relates to a device for projecting and priming an exploding charge laid underground, in particular an extended range mine of the anti-personnel type.

Known for many years have been so-called extended range mines of the anti-personnel type. These devices are substantially formed of an igniter overlying two casings buried in the ground, the one inside the other. Into the outer casing a propelling charge is inserted, and a main charge is inserted into the inner casing. Also provided are priming members which, as the projecting charge explodes and the inner casing reaches a set distance off the ground, cause the cited main charge to explode, with attendant projection of splinters all around the mine.

These prior devices must be provided with at least one pair of detonators, one for the projecting charge and another for the main charge, at least one pair of strikers for said detonators, and separate control members for said strikers comprising the cited igniter and said priming members. Further, in most instances, an auxiliary charge is added to the main and projecting charges which acts as an intermediary between the main charge and its detonator.

Furthermore, both said containers must be properly constructed to allow the inner one to be actually projected out of the ground and to provide the space required for first expansion of the gases issuing from the projecting charge.

It may be appreciated that the construction of such devices is liable to be a relatively complex one, and this complexity has prompted a variety of approaches, in many cases unsuccessful in terms of reliability and simplicity. In fact, in many cases, the projecting charge cannot be removed unless the mine is taken apart completely, and said detonators are not within easy reach. That is, it is not generally possible to take out, with a single operation, all of the most sensitive or hazardous elements present in this mine type.

Accordingly it is a general object of this invention to provide a device for projecting and priming an exploding charge laid underground, which can obviate the deficiencies of the cited extended range mines of the antipersonnel type currently known and has a very simple, yet specially functional and efficient, construction.

This object is substantially achieved by a device for projecting and priming an exploding charge laid underground, of a type which comprises: an igniter mounted on a first casing to be buried underground, a projecting charge connected to said igniter and being inserted into said first casing, a second casing containing a main charge and being also inserted into said first casing, and priming members for said main charge inserted between said first and second casings, said device being characterised in that in said first casing there is inserted a pull-out cartridge element having its ends first and second detonators for priming respectively said projection charge and said main charge, said detonators confronting respectively a first striker housed in said igniter and a second striker placed substantially at the bottom of said first casing, at said priming members for said main charge, and in that said projection charge is located in said cartridge element adjacent to said first detonator and to a conduit arranged to convey to the bottom of said first casing the gases released by said projection charge, a space being left for said gases between said casings.

Further features will become apparent from the following description of a preferred embodiment of the invention, with reference to the accompanying drawing, where: the one drawing figure shows comprehensively and in cross-section the device of this invention.

With reference to the drawing figure, a device according to the invention is generally indicated at 1. It forms an extended range antipersonnel mine comprising an igniter 2 mounted on a main body 3 for laying underground; The igniter 2 comprises a rocker element 4 connected above to tripping strings 5 and being lockable by means of a safety pin 6. The rocker element 4 has at the bottom a shaped pressure plate 7 which is journalled to a containment element 8 with its top edges 7a.

Inserted into the element 8 (to contact the pressure plate 7) is a bell-like element 9 bearing on a first compression spring 10 interposed to the bell-like element 9 and a first striker 11. In between the sidewalls of the bell-like element 9 and the first striker 11, there is inserted a tube 12 formed with a through-going seat accommodating a small ball 13. This ball normally protrudes from the side of the first striker 11, and inhibits its movement toward a first detonator 14 located at the bottom of the igniter 2. Formed in the bell-like element 9 is a recess 9a adapted to receive the ball 13 partway therein to enable the ball to release the first striker 11. The recess 9a is normally held off the ball 13 and only aligns to it on the rocker element 4 pushing on the bell-like element 9 against the bias of the first compression spring 10.

The containment element 8 is threaded into a fitting 15, in turn threaded to the main body 3 by means of a ring-like element 16.

The main body 3 has a first outer casing 17 provided with a screw-on cover 17a. The cover 1 7a has weakened regions 18 in the vicinity of the cover edges. The cover 1 7a is apertured centrally to receive the ring-like element 16.

The latter is advantageously threaded directly, at its outer surface, to a second casing 19 that contains a main charge 20 and splinters 21. The second casing 19 extends as a toric belt to leave a relatively broad central region 22 and a bottom space 23 available.

Between the igniter 2 and the space 23 there lies, in the central region 22 of the main body 3, a cartridge element 24. The latter is engaged above with the interior of the ringlike element 16 and comprises at its top end and bottom end, respectively, said first detonator 14 and a second detonator 25. Furthermore, the cartridge element 24 comprises on its interior a projection charge 26 located close to the first detonator 14. The latter is inserted into a bowl container 27 having a thinned portion 27a that breaks out under the pressure developed on blasting the projection charge 26, whereas the bowl container 27 would withstand the pressure. The thinned portion 27a confronts the central region 22 at 8 section thereof which defines substantially a conduit 28 adapted to convey said gases from the bowl container 27 into the space 23.

Also inserted in the central region 22, in a protected location, is an auxiliary charge 29 intervening between the second detonator 25 and the main charge 20.

At the bottom of the cartridge element 24, within the space 23, there are inserted priming members acting on the second detonator 25 and, hence, on the auxiliary charge 29 and main charge 20. These priming members comprise a second striker 30 inserted into a barrel 31 aligned to the cartridge element 24 and to the second detonator 25, a second compression spring 32 interposed to an expansion 30a of the second striker 30 and the barrel 31, a release nib 33 connected to the second striker 30, and a string 34 connecting the release nib 33 to the bottom of the first casing 17.

The release nib 33 fits, with one end, partway into the second striker 30 and with the opposite end into a cutout in the barrel 31, thereby forming a stop to the forward movement of the second striker 30. The release nib 33 is releasable from the second striker 30 on pulling by the string 34 and driving it out of the barrel 31.

The string 34 is a pull string of a plastic material moulded directly to a spiral pattern and laid at the bottom of the first casing 17.

The length of this pull string is directly proportionai to the height over the ground at which the main charge 20 should be primed, as the second casing 19 is ejected upwards from the first casing 17.

It should also be noted that, advantageously, the auxiliary charge 29 is arranged to be directly withdrawable from the main body 3 following raising of the igniter 2 with the cartridge element threaded thereto.

Sealing gaskets are provided between the cover 1 7a and casing 17, and between the fitting 15 and cover 17a, on the one side, and the igniter 2 on the other side.

The device just described operates as follows.

The main body 3 is buried in the ground with the igniter 2 installed and standing out of ground. The igniter 2 is then attached the tripping strings 5 and the safety pin 6 is removed which locks the rocker element 4.

As the string is struck, the rocker element 4 of the igniter 2 tilts over and the pressure plate 7, by pivoting about a portion of the top edge 7a, rotates to press on the bell-like element 9. The latter will then move downwards and first compress the first compression spring 10 while the first striker 11 is locked by the ball 13. On the downward movement of the bell-like element 9 bringing the recess 9a to the same level as the ball 13, the latter will move toward the element 9 and release the first striker 11. The energy stored in the first compression spring 10 can thus be released to project the first striker 11 against the first detonator 14. The first detonator 14 primes the projection charge 6 and the pressure generated within the bowl container 27 will break out through it at the thinned portion 27a.

The gases flow then down the conduit 28 and expand in the space 23, thus generating a thrust force which is applied to the second casing 19, toward the cover 17a. The latter has the weakened regions 18 and will, therefore, be sheared off at once at the same and allow the second casing 19 and all the mine elements to be thrown up, with the sole exception of the first casing 17 and the string 34, which is stretched out of its coiled initial position.

On the second casing 19 reaching a set elevation, the string 34, being attached with one end to the bottom of the first casing 17, will pull on the release nib 33. The latter pulls the second striker 30 to compress the second compression spring 32, until the release nib 33 comes fully out of the chamber 31 and releases the second striker 30.

Once released, the second striker 30 is subjected to the action of the second compression spring 32 which projects it against the second detonator 25. Thus, the explosive chain is started because the second detonator 25 will prime the auxiliary charge 29, also commonly termed booster charge, which fires the main charges 20, throwing the splinters 21 all around the mine axis through an arc of 360 .

Among the advantages afforded by the invention, the fact should be mentioned that a cartridge element 24 has been provided which contains both detonators 14 and 25 as well as the projection charge 26. The cartridge ele ment 24 can be taken fully out, as can the igniter 2.

The igniter 2 operates both on applying a sharp pull or a compressive force to it, and is highly resistant to counter-measures, owing to the small surface area exposed to the shock waves. Also, in the igniter 2, a very simple and functional firing device is provided for the striker 11. Also advantageous is the expedient of providing a plastics pull string 34 which is kept coiled because originally moulded in that shape.

The projection charge 26 accommodated in the upper area of the mine, with the ejection gases that flow down into the lower area, greatly simplifies the device construction, which is accordingly more reliable.

Claims (7)

1. A device for projecting and priming an exploding charge laid underground, of a type comprising: an igniter mounted on a first casing to be buried underground, a projection charge connected to said igniter and being inserted into said first casing, a second casing containing a main charge and being also inserted into said first casing, and priming members for said main charge, inserted between said first and second casings, said device being characterised in that in said first casing there is inserted a pull-out cartridge element having at its ends first and second detonators, for priming respectively said projection charge and said main charge, said detonators confronting respectively a first striker housed in said igniter and a second igniter placed substantially at the bottom of said first casing, at said priming members for said main charge, and in that said projection charge is located in said cartridge element adjacent to said first detonator and to a conduit arranged to convey to the bottom of said first casing the gases released by said projection charge, a space being left for said gases between said casings.

2. A device according to claim 1, characterised in that both said igniter and said cartridge element can with withdrawn out of said casings and that an auxiliary charge is provided which partially surrounds said cartridge element and is adapted to boost the action of said second detonator on said main charge, said auxiliary charge being also arranged substantially centered on said second casing.

3. A device according to claim 1 or claim 2, characterised in that said second striker is movable in a barrel facing said second detonator, on an impulse from a second compression spring interposed to the bottom of said barrel and an expansion of said second striker, and that the striker is connected to a release nib attached to one end of a string the other end of which is attached to said first container.

4. A device according to claim 3, characterised in that said release nib is engaged on one side with said second striker and on the other side with a cutout in said barrel and is movable from a starting position where it bottoms out in said cutout so as to inhibit forward movement of said second striker to a final position outside said barrel where the nib is released from said second striker.

5. A device according to claim 4, characterised in that said string is a pull string moulded directly in spiral form from a plastic material.

6. A device according to any preceding claim, characterised in that said igniter comprises a rocker element acting through a pressure plate on a bell-like element surrounding a first striker, between said first striker and said bell-like element there being inserted a first compression spring and said first striker being engaged by a small ball being movable conformingly with a recess formed in said bell-like element, said recess being aligned to said ball with said bell-like element bottoming out against the bias force of said first compression spring.

7. A device for projecting and priming an explosive charge laid underground, substantially as herein described with reference to the accompanying drawing.