FR2526150A1 - PYROTECHNIC RETARDER FOR DETONATION WAVE - Google Patents

Abstract

DEVICE USED IN AN EXPLOSIVE SYSTEM IN THE FORM OF TWO EXPLOSIVE CHARGES OPERATING IN DETONATION REGIME, THE DETONATION OF THE FIRST CAUSING THAT OF THE SECOND AND INTENDED TO CREATE, BETWEEN THE DETONATION OF THE FIRST CHARGE AND THAT OF THE SECOND, AN INTERVAL OF TIME OF DETONATION TO ALLOW CORRECT OPERATION OF THE SYSTEM, THIS DEVICE BEING CHARACTERIZED IN THAT IT IS CONSTITUTED BY A REVOLUTION BODY ESSENTIALLY INCLUDING AT LEAST ONE MEANS MODIFYING THE CHARACTERISTICS OF THE PROPAGATION OF THE DETONATION WAVE OF THE FIRST LOAD, TO CREATE A DELAY ON INITIATION OF THE SECOND CHARGE AND LEAVING AN AXIAL VACUUM AUTHORIZING A PASSAGE OF MATERIAL FOLLOWING ITS AXIS, WITHOUT AFFECTING ITS OPERATION AND ROLE.

Description

The present invention relates to a device intended to be

  used in an explosive system consisting of two explosive charges operating in a detonating regime, the detonation of the first of which causes the detonation of the second with, between the end of the detonation of the first and the initiation of the detonation of the second, an interval of fixed time, chosen for

  allow correct operation of the system.

  The device according to the invention consists of a pyro-

  technique, placed between the two explosive charges of the system, which ensures the physical continuity of the detonation wave, generated by the first charge, by modifying the speed of its propagation, so as to create a delay (4 tr)

  at the initiation of the second charge, which is then initiated by the deto wave -

  nation, adapted to the pyrotechnic characteristics (speed, pressure)

of this charge.

  The device according to the invention is characterized in that it is

  titrated by a body of revolution comprising essentially at least one means modifying the characteristics of the propagation of the detonation wave of the first charge, to create a delay in the initiation of the second charge and leaving an axial vacuum allowing a passage of material along its axis, without

  that its functioning and role are affected.

  According to another characteristic of the invention, the device is

  provided with means intended to deliver, downstream of the device, a detonation wave

  tion whose characteristics are adapted to the characteristics of the second charge. The various characteristics and advantages of the invention will emerge

  of the description, which will follow, of some of its possible forms

  of realization, given only by way of nonlimiting examples, of-

  the description made with reference to the appended drawings of which V Fig 1 to 7 are schematic views, some in section, others in perspective, of these

  embodiments, as well as an example of application of the invention.

  In general, the device according to the invention is in the form of a body of revolution, specifically, in the examples treated in the form of a cylinder A. This device is, as shown in FIG 2, inserted between a primary charge provided with an al initiation and a secondary charge jb, the

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  two charges operating encascade, the detonation wave emitted by

  charge a, causing the secondary charge to start b.

  The device comprises, as a means intended to delay the detonation wave of the charge b, a pyrotechnic relay c, of annular shape and which consists of a pyrotechnic composition, of high density, with low

detonation speed.

  The arrangements adopted and the form of the pyrotechnic relay c make it possible to provide, in the axis of the body A empty space allowing,

  for certain applications, a material passage which does not affect either its function-

neither, nor its role.

  The device also includes an entry screen

  inert, for the ignition of relay c at the detonation pressure of the compound

  tion of which it consists and of its priming; as well as an enhancer f, wave output This enhancer is intended to adapt the detonation wave

  to the detonic characteristics of the secondary charge b.

  These characteristics are chosen according to those of the retarder relay c and the secondary load b Screen e and booster f are

also ring shape.

  The delay caused in the initiation of the secondary or downstream load b is a function of the length of the device. However, to increase the value of the delay, there can be no question of increasing the length of the device in proportions quickly becoming inadmissible in most. application cases. It is therefore ultimately a question of obtaining the longest possible detonation time of the device, using a bulk device

  and as small a mass as possible.

  This goal is achieved by using, as a relay, a composition

  pyrotechnic not in the form of a one-piece unit, but pre-

  feeling in the form of separate elements, constituted for example by

  parallel columns, always having a symmetry of revolution.

  The weight of the relay having thus been reduced - one can, to increase the duration of the delay which it determines give, as shown in Fig 4, a spiral movement to the columns e, thus increasing the path of the wave

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  detonation according to the pitch of the turns.

  It is also possible, as shown in Fig 5, to double the name-

  bre of the columns e by distributing it in the form of two inverted spirals, which determines a mesh relay & The only condition is that the detonation wave passing through the device, arrives at the same instant at each node

large mesh.

  Any other form of mesh network can be used -

  such as that represented, understood by way of example, in FIG. 6, in

  which the different stages of columns e are connected S by annular bridges

  parallel spaces h. Between the pyrotechnic parts, constituting the columns or the meshes, one can interpose an inert material i, to avoid possible

interactions between the stitches.

  At the rear part of the device, a part j comprising holes X filled with an active or inert material, constitutes a wave rectifier, this rectifier being followed by a enhancer f which has been discussed

upper.

  FIG. 7 shows an example of application of the device according to the invention to an explosive system comprising two hollow charges 1 and Z arranged in tandem and operating in cascade, the operation of the first, initiated by the single initiation 3 having to initiate the operation

  of the second with a delay On the order of magnitude of the hundred of 5.

  The device according to the invention, placed between the two charges, transmits by adapting it, the detonation wave produced by the upstream charge

  at the second charge, generating a time interval between operation

  ment of the two charges, a function of its detonic and geo-characteristic

  metrics The recess in the center of the device allows the passage of the

upstream or primary load.

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Claims (9)

  I Device used in an explosive system made up of two   explosive charges operating detonating regime, detonation of the prre-   matter causing that of the second and intended to create, between the detonation   of the first charge and that of the second, a deter-   mined to allow proper functioning of the system, this device   being characterized in that it is constituted by a body of revolution com-   essentially carrying at least one means modifying the characteristics of the propagation of the detonation wave of the first charge, to create   a delay in initiating the second charge and leaving an axial vacuum allowed   sant a passage of material along its axis, without its operation and its role will be affected.   2 Device according to claim 1, characterized in that it   is equipped with means intended to deliver, downstream of the device, a wave of   tonation, the characteristics of which are adapted to the characteristics of the second charge.   3 Device according to any one of the preceding claims.   teeth, characterized in that it comprises, as a means for delaying the transmission of the detonation wave, a pyrotechnic relay c, of annular shape and which consists of a pyrotechnic composition, of high density, at low detonation speed.   4 Device according to any one of the preceding claims.   teeth, characterized in that it comprises an input screen e in inert material, for priming the relay c at the detonation pressure of the composition   of which it is made up and its initiation.   5 Device according to any one of the preceding claims.   teeth, characterized in that it is provided with an output enhancer (f), intended to adapt the wave of detonational detonic characteristics of the secondary charge È,   6 Device according to any one of the preceding claims.   teeth, characterized in that the delay relay (c) is located under the   form of separate elements, made up of parallel columns (e), in a symmetry of revolution.   7 -A device according to any of the preceding claims   teeth, characterized in that the columns (e) are spiral.   8 Device according to claim 7, characterized in that   the columns (e) are distributed in two inverted spirals.   9 -A device according to claim 6, characterized in that the parallel columns (e) are arranged parallel to the axis of the body (A)   and joined by annular bridges (h).   -Device according to any one of the preceding claims   teeth, characterized in that an inert material (i) is interposed between the pyrotechnic parts constituting the columns, or the mesh meshes formed by them.