FR2478808A1 - PYROTECHNIC DELAY MODULE AND LOADING METHOD THEREOF - Google Patents

Abstract

THE PRESENT INVENTION CONCERNS A PYROTECHNICAL DELAY MODULE OF THE TYPE CONTAINING, SUCCESSIVELY, MIXTURES OF PULVERULENT COMPOUNDS CONSISTING OF AN IGNITION COMPOSITION, A DELAY COMPOSITION, AND, OPTIONALLY, A REINFORCING COMPOSITION. THIS MODULE IS CHARACTERIZED IN THAT THE IGNITION COMPOSITION IS IN THE FORM OF A COATED MIXTURE, THE DELAY COMPOSITION IN THE FORM OF A PELLET OR COATED MIX, AND THE STRENGTHENING COMPOSITION IN THE FORM OF A DRY MIXTURE. TO LOAD SUCH A MODULE, ONE SUCCESSIVELY LOADS, WHILE COMPRESSING THEM, AN IGNITION COMPOSITION IN COATED FORM, A DELAY COMPOSITION IN PELLET OR COATED FORM, AND A STRENGTHENING COMPOSITION IN DRY MIXED FORM. APPLICATION TO IGNITERS, FOR EXAMPLE OF GRENADES.

Description

A \ 2478838

  PYROTECHNIC DELAY MODULE AND LOADING METHOD THEREOF

  The technical field of the present invention is that of pyrotechnic devices intended to perform various functions such as delay, ignition, illumination, tracing,

  gas or smoke generator, etc. These devices are con-

  staged a pyrotechnic chain comprising several superimposed elements. These elements each have their own role and

  must transmit the phenomenon to the next element of the chain.

  They consist of mixtures called "pyrotechnic compositions"

  placed in a metal support such as for example a tube.

  These mixtures comprise different solid compounds and are formulated considering the function they must fulfill; primary or secondary explosives, oxidizing agents, reducing metals or compounds, various additives intended either to promote mixing or to confer on the composition particular properties such as electrical conduction, thermostability or sensitivity to

certain actions.

  However, they must also meet other practical constraints of use, among which we find: homogeneity and reproducibility of the proportions, flowability for a volumetric dosing, generally of industrial type, insensitivity to the external hygrometry and especially safety to the

  times of the mixing process and the operations of implementation.

  The manufacture of a pyrotechnic device comprises the introduction, or loading, of the elements of the pyrotechnic chain and is done by introducing into the pulverulent solid state amounts perfectly dosed in volume or mass of each pyrotechnic composition that must be previously put in shape. 24 78 8 q8 It is already known, in current industrial practice,

  the simple dry blending of several solid crystalline

  whether or not they are more or less hygroscopic, of different real densities, of spread and often very fine particle size,

  is sometimes difficult if not impossible.

  However, various granulation processes are known to obtain homogeneous mixtures of several solid compounds that can be used industrially. These methods most often involve the introduction into the mix of an addition substance

playing the role of binder.

  The shaping of these mixtures can therefore be done in several ways: - dry blending of the pulverulent compounds - mechanical granulation through grids

- coating with a binder.

  The methods chosen, for each of the elements of the pyrotechnic chain, often have a number of drawbacks among which may be mentioned: - homogeneity difficult to ensure and causing either an impossibility of dosing, or a too large dispersion in the operating can go until râté, - sensitivity of the compositions to 1 hygrometry external compromising their dosage and their subsequent stability, - scrap rate significant imposing additional operations sorting by sieving or remaking of certain fractions, - accidents or incidents due to unintentional excitation of composition during mechanical operations on

sensitive compositions.

  In addition, in the particular case of a pyrotechnic chain for an igniter plug, of a grenade for example, comprising successively an ignition composition, a

  pyrotechnic delay and possibly a reinforcing composition

  or "unblocking", the simultaneous implementation, especially in an automatic loading machine, of these various solid compounds is delicate. Indeed, the ignition compositions are sensitive to friction and heating and have a particle size and a nature that make them

  slightly hygroscopic, while the pyrotech compositions

  niques acting as delay are mechanically less sensitive but imply a perfect homogeneity and a great regularity.

loaded mass.

  The present invention proposes a pyrotechnic device of the latter type, having an easy loading method, especially in an automatic machine for loading ammunition, and which has improved reproducibility, aging and performance characteristics, while eliminating the aforementioned drawbacks. fit for formatting

  of the various components of a pyrotechnic chain.

  The subject of the present invention is therefore a pyrotechnic delay module, of the type comprising mixtures of powdery compounds successively stacked in a tube and consisting of an ignition composition, a retardation composition, and, optionally, a reinforcing composition, characterized in that the ignition composition is in the form of a coated mixture, the delay composition is in the form of a granular or coated mixture, and the reinforcing composition

form of dry mix.

24788 '8

  The invention also relates to a method for charging a pyrotechnic module as described above, characterized in that successively, while compressing them, an ignition composition in the form of a coating, a delayed granulated or coated form, and a reinforcing composition in dry mixed form. The invention therefore makes it possible to produce a pyrotechnic ring by sequentially dosing, and in particular volumetrically, the pulverulent state of the known compositions obtained. form, in particular by the process by different processes / coating of pyrotechnic substances

  described in French Patent 2,309,493 in the name of PETAT FRANCAIS.

  It is recalled that this method makes it possible to obtain directly, without prior mixing, without mechanical operation source of incidents, without sorting at the output, a pyrotechnic composition, in particular ignition or delay, homogeneous, reproducible,

  perfect flowability and reduced hygroscopicity. It includes essential-

  the following steps diluted solution of a coating polymer in a solvent, X monique or not, at a concentration by weight of 2 to 20%; * introduction of 10 to 60% by weight of the powdery pyrotechnic composition to be coated, with appropriate stirring to maintain a homogeneous dispersion of the particles, progressive addition with stirring of one or more liquid or viscous two opposing polyners for which the aforementioned solvent has a higher affinity large than for the preceding coating polymer, until a concentration by weight of between% and 60% of the total weight is obtained, filtration to separate the plasticized grains from the residual liquid phase, then washing of these grains, - finally, drying during a few hours of these

  grains, in the open air or in an oven.

  Similarly, the granulation of the delay composition can be carried out in a known manner, by introducing the composition into a planetary kneader, a binder, and at least one solvent, until the composition is wet well and obtained. a fluid and homogeneous paste. After drying, this

  paste is introduced into a rotating granulator operated remotely.

  The granule obtained is spread and dried, then sieved between 80 and 200 μ to obtain a granular retardation composition suitable for industrial loading. Finally, and in a known manner, the reinforcing composition is prepared by simple dry blending with a rotary mixer.

or unblocking.

  This pyrotechnic module, intended to equip for example mines, torpedoes, destruction charges, can be manufactured in large series, without hygrometric stress, using weight loading machines or volumetric, and has a great regularity of operation, a good reliability and a good

  aging behavior, as shown below.

  By way of nonlimiting example, the unitary loading of 30 pyrotechnic delay modules is introduced by successively introducing into each tube placed in a matrix the

  following compositions after weighing in the precision balance.

*** / -. * -.

24788C8

  130 mg of ignition base coated according to the process described in French Pat. No. 2,309,493; 70 mg of granulated retarded caoposition according to a known mechanical method and then ccmpressing with a conical punch under a pressure of 190.degree. Pascals, - 200 mg of granulated retardation cohesion as above, then performing a new caopression at 190 x 10 pascals, and then adding: - 70 mg of granulated delay composition above, - 100 mg of ccposite intensifier mixed with the rotary mixer. We then perform a final compression with a punch

  flat under a pressure of 190 x 106 pascals.

  The finished tubes are then equipped with a primer

  cussion. Their falling sheep shooting with delay measurement gives the following results:

  - Average delay time: 5.8 s': with a standard deviation of 0.18 s.

  The following table compares the results obtained

  by pyrotechnic modules loaded with pyrotechnic

  techniques variously shaped by the known methods mentioned above.

  born higher. The series of modules were subjected for four days at a relative humidity of 100% at 35 C and then out of the oven; primed and pulled with falling sheep. All modules contain a single intensifying coposition simply mixed

dried up.

2 788 8

  average! burning time! % function-: maximum delay minimum ()) ((s) (s) i - - 1 (s) ,, 1 mixed dry start dry mixed delay 2 mixed ignition delay granule 3 mixed ignition granular retardation mixed ignition granulated retard granulate 6 ignition granular coated delay 7 fired ignition mixed delay 8 fired ignition delay granular 9 fired ignition coated delay ooo

7.2

i

7; 6.7

8, 2

7 4.5

6.9 6.8

7,1i

7, 1 [

6, 8, 7, 7.4, 7.4, 7.4, 1,

7.1 1

/ ...

24788 C -

-8 -

Claims (4)

REVENDIC2TIONS   1 - Pyrotechnic delay module of the type comprising, successively   mixtures of powdered caomosés consisting of a mixture of   ignition position, in a delayed coaposition, and, possibly,   in a reinforcing position, characterized in that   The ignition position is in the form of a coated mixture, the delay composition is present in granulated or coated mixture, and the reinforcing layer in the form of a dry mixture. 2 - A method for charging a pyrotechnic module according to claim 1, characterized in that successively, while compressing, a c = ignition position in coated form, a delay composition in granulated or coated form ,   and a reinforcing creposition in dry melted form.   3 - Process according to claim 2, characterized in that, at   As they were introduced in the module, the cau-   are subject to a carpression of about 190 x 106 pascals.   4 - Process according to claim 3, characterized in that it comprises the following successive stages: - loading of all of the ignition composition, - loading of about 20% of the delay composition, - compression with a punch conical under approximately 190 x 106 pascal - loading of approximately 60% of the delay composition, camming with a conical punch at approximately 190 x 106 pascal   - loading the rest of the delay composition, then the   reinforcing position, - last compression with a flat punch under approximately 190 x 106 pascals. -s, Ls