GB2134230A

GB2134230A - Mine activation device

Info

Publication number: GB2134230A
Application number: GB08333786A
Authority: GB
Inventors: Vito Taddeo
Original assignee: VALSELLA MECCANOTECNICA SpA
Current assignee: VALSELLA MECCANOTECNICA SpA
Priority date: 1982-12-27
Filing date: 1983-12-19
Publication date: 1984-08-08
Also published as: ZA839493B; IT8224998A1; IT8224998A0; IT1153919B; GB8333786D0

Abstract

An activation device (1) for a mine provided with an uncovering charge and a bursting charge includes, in a single tubular container (2) having a closed end, a first portion (5) provided with holes 7 and containing a primer mixture (9), a second portion (6) containing an explosive mixture (10), and a pyric retarder (15). This device (1), which can be easily inserted in and removed from the mine as necessary, allows the ignition of the uncovering charge through the holes 7 at a predetermined time before the bursting charge in a safe and reliable manner. <IMAGE>

Description

SPECIFICATION Mine activation device The present invention relates to a mine activation device.

It is known that, to advantage, mines include a main bursting charge and an auxiliary deflagrating charge, usually of black powder, which is ignited just before the main charge in order to free the mine from the overlying soil so that the effect of the explosion of the main charge can be more direct and lethal. More particularly, the period of time is fixed so that the main charge explodes when the soil is dispersed in air and has not yet started to fall back to the ground. The auxiliary deflagrating charge is called the primary uncovering charge of the mine, while the main charge is called the bursting charge.

In order to satisfy this requirement, two separate electrical activator elements are used at present, the first triggering the primary uncovering charge and the second triggering the bursting charge after a delay.

Although advantageous from various aspects, the solution which uses two separate activators has several disadvantages such as: -two connections to the activators (electrical connections) and hence reduced reliability; -the presence of at least one activator in the mine even during storage (safety conditions not complied with fully).

The problem behind the present invention is that of providing a mine activation device which does not require connections and is constituted by a single element.

Accordingly, the present invention provides a mine activation device which includes, in a single tubular container having a closed end, a first, apertured portion close to the mouth of the container containing a priming deflagrating mixture, a second portion close to the bottom of the container containing an explosive mixture, and a pyric retarder housed in the container between the first and second portions.

A preferred embodiment of the present invention will now be described with reference to the accompanying drawing which is a sectional view of a mine activation device according to the present invention.

With reference to the drawing, a mine activation device, generally indicated 1, comprises a single metal tubular container 2 which has a mouth 3 at one end and a bottom 4 opposite the mouth.

The container 2 defines a first portion 5 close to the mouth and a second portion 6 close to the bottom.

The portion 5 is apertured by small-diameter holes 7 which are closed by respective layers 8 of varnish, for example nitro-cellulose varnish.

The portion 5 contains a first, deflagrating mixture 9 constituted by potassium perchlorate, aluminium powder and an additive known commercially as "Steroterc" in proportions of 65%, 35% and 1%, respectively.

This mixture constitutes a generator of hot gas intended to ignite the primary uncovering charge of the mine and to trigger the pyric retarder.

The portion 6 close to the bottom contains a second explosive mixture 10, while there is a pressed inert layer 11 at the bottom 4.

The second mixture 10 includes a layer 1 2 of pressed penthrite adjacent the inert layer 11, another layer 1 3 of pressed penthrite, and a layer 14 of pressed lead azostifnate.

This mixture constitutes the detonator of the main charge of the mine.

The inert layer 11 is constituted, for example, by pressed sugar.

The device 1 also includes a pyric retarder 1 5 mounted in the container 2 between the first portion 5 and the second portion 6.

More particularly, the pyric retarder 1 5 is constituted by an apertured plug 1 6 and a retardent-carrying body 1 7 containing, in addition to a retardant cylinder 18, the transmisssion cap 1 9 which ignites the underlying mixture 1 4 at the end of the delay.

A primer cap, generally indicated 20, is force-fitted in the mouth 3 of the tubular container 2 and is arranged to be struck by a striker 21 shown in chain outline. A squibtype electrical initiator may be used instead of the primer cap and striker.

The operation of the activation device according to the invention is now described with reference to one of its uses inserted in the casing of a mine in such a position that the portion 5 is surrounded by the uncovering charge and the remaining portion of the container is surrounded by the bursting charge.

At the moment of striking of the primer cap 20 by the striker 21, the burning of the first mixture is initiated and this ignites the uncovering charge through the holes 7 which are easily passed through by melting of the layers 8 of varnish; this causes an explosion which removes soil from the mine itself.

The burning of the first mixture is also transmitted through the apertured plug 1 6 to the pyric retarder which burns through in a predetermined period of time.

At this point the pyric retarder ignites the transmission cap 1 9 which causes the ignition of the second mixture. This detonates with a radial effect, causing the detonation of the bursting charge of the mine.

The delay between the ignition of the uncovering charge and the bursting charge, instead of resulting from two signals from the exterior for separate primers, is achieved through the successive ignition of two mixtures caused by a single combustion front along which is provided a suitable pyric retarder, the mixtures and the pyric retarder being housed in a single container.

By virtue of this, the device according to the invention has the important advantage of allowing the desired detonation of the mine to be achieved at two different times without two successive signals and hence in a safe and reliable manner.

A further important advantage of the device according to the invention results from the fact that it is housed in a single container and lies in the fact that it can easily be inserted in and removed from the mine as necessary, for example, when the mine is intended for use or must be stored.

Claims

1. A mine activation device including, in a single tubular container having closed end, a first, apertured portion close to the mouth of container containing a priming deflagrating mixture, a second portion close to the bottom of the container containing an explosive mixture, and a pyric retarder housed in the container between the first and second portions.

2. A mine activation device substantially as herein described with reference to, and as shown in, the accompanying drawing.