FR2840402A1 - ENCLOSURE GENERATING CHIPS, EXPLOSIVE CHARGE AND AMMUNITION IMPLEMENTING SUCH AN ENVELOPE - Google Patents

Abstract

The technical sector of the invention is that of envelopes generating splinters for explosive charge. The envelope (2) according to the invention is characterized in that it is made of a tungsten alloy having a resilience greater than 120 J / cm2, an elongation rate greater than 10% and a breaking strength greater than 930 Mpa.

Description

s

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  The technical field of the invention is that of

  shrapnel-generating envelopes for explosive charges.

  The known explosive charges generally comprise a steel envelope, weakened or not, or else an envelope comprising preformed fragments (balls or

  parallelepipedes) arranged between two etuls.

  The patents FR2807156, US5544589 and EP918206 describe

  envelopes generating known fragments.

  The increase in the resistance of the targets leads to seek an increase in the terminal efficiency of the

explosive charges.

  Such and such. the increase can and re obtained by

  increasing the mass and efficiency of the flakes.

  The flakes are all the more effective as their IS geometric is mastered. It's easy to subdue the

  geometric by using preformed flakes.

  However, such a solution is penalizing from the point of view of cost because the structure of the explosive charge is complex, and in particular includes cases for holding the

bursts.

  Such a solution also leads to defining multi-layer envelopes. This reduces the mass of the explosive charge carried and the yield, therefore the terminal efficiency due to the decrease in the

burst speed.

  Efficiency can also be increased by

  increased density of flakes.

  However, dense materials (tungsten, uranium), which are usually used in explosive projectiles, do not generate large fragments.

and sufficient mass.

  Patent EP113833 thus describes an explosive projectile comprising a tungsten body. However, the fragments generated by such a projectile are not homogeneous and include in particular a tungsten dust having no

perforating effect.

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  It is the aim of the invention to propose a casing generating splinters having an efficiency improved by

compared to known envelopes.

  Thus, the subject of the invention is an envelope S generating flakes for explosive charge, an envelope characterized in that it is made of a tungsten alloy having a resilience greater than 120 J / cm2, an elongation rate greater than 10% and a resistance at break greater than

930 Mpa.

  Preferably, the envelope will be made of a tungsten alloy having a resilience greater than or equal to 200 J / cm2, an elongation rate greater than or equal to 22% and

  a tensile strength greater than or equal to 1000 Mpa.

  The envelope can be made of a tungsten alloy having: a resilience of 380 J / cm2, an elongation rate of 35% and a breaking strength of 1020 Mpa, or a resilience of 320 J / cm2, a rate of 7 elongation of 30% and a tensile strength of 1060 Mpa, or a resilience of 200 J / cm2 r an elongation rate of 22G

  and a breaking strength of 1150 Mpa.

  Advantageously, the thickness of the envelope will be understood

between 2 mm and mm.

  The envelope can carry a network of lines of embrittlement. This embrittlement can be carried out over a depth of between 2% and 50% of the thickness of the envelope. The invention also relates to an explosive charge generating fragments incorporating such an envelope as well.

  an ammunition comprising such an explosive charge.

  The charge according to the invention has a higher efficiency than that of known flash charges because it generates

  homogeneous flakes and of higher mass.

  In addition it incorporates a generator generator envelope which can have a simple geometric, thus facilitating

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  industrial implementation, and allowing the carrying of a large explosive charge mass' which increases the speed of the fragments, therefore their efficiency. Thus the explosive charge generating fragments according to the invention comprises an explosive charge placed in a flash generator envelope as well as at least one initiator for this loading, it is characterized in that the chip generator envelope is made of a tungsten alloy having a resilience greater than 120 J / cm2, an elongation rate greater than 10% and a tensile strength greater than 930 Mpa Preferably, the envelope will be made of a tungsten alloy having a resilience greater than or equal to 200 J / cm2, an elongation rate greater than or equal to 22% and a

  tensile strength greater than or equal to 1000 Mpa.

  The envelope can be made of a tungsten alloy having: a resilience of 380 J / cm2, an elongation rate of 35% and a breaking strength of 1020 Mpa, or a resilience of 320 J / cm2 / un elongation rate of 30% and a tensile strength of 1060 Mpa, or a resilience of 200 J / cm2 F an elongation rate of 22%

  and a breaking strength of 1150 Mpa.

  The fragment-generating envelope may have a thickness of between 2 mm and 8 mm and carry a network of

lines of weakness.

  The embrittlement can be carried out over a depth between 2% and 50% of the thickness of the envelope Advantageously the envelope can be closed by at least one cover having a cylindrical bearing at the level of which it is positioned, cover including the envelope will be made integral by transverse screws,

by laser welding or by soldering.

  Preferably at least one cover will be made of a material with a density lower than that of the material.

  casing, for example stainless steel.

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  The munition according to the invention is characterized in that the envelope provides the mechanical connection between a front part and a rear part of the ammunition thus forming a

  part of the structure of the ammunition body.

  s The invention will be better understood on reading the

  description which follows of particular modes of

  realization 'description made with reference to the figures

  annexed and in which o - Figure 1 is a longitudinal section of an explosive charge according to a first embodiment of the inventionr - Figure 2 is a longitudinal section of an explosive charge according to a second embodiment of the invention '- Figure 3 is a longitudinal section of an explosive charge according to a third embodiment of the invention, - Figures 4 and 5 are external views of a charge according to the invention showing the geometric lines of weakness, - Figure 6 shows in partial longitudinal half section a munition incorporating a charge according to

the invention.

  Figure 1 shows an explosive charge 1 comprising a 2s envelope 2 closed at each end by a cover 3 and 5

  and containing an explosive charge 4.

  The cover 5 carries a detonator 6 as well as one or more detonation relays 7 of suitable mass and shape. In accordance with the invention, the casing 2 is made of a tungsten alloy having a resilience greater than 120 J / cm2, an elongation rate greater than 10% and a tensile strength greater than 930 MPa (mega pascals). The density of the tungsten alloy will be between 3s 17 and 18.8, which corresponds to a tungsten rate included

between 90% and 98%.

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  The thickness of the envelope 7 will preferably be between 2 and 8 mm. This thickness will of course be determined

  depending on the size of the load considered.

  The covers 3 and 5 will preferably be made of a material S having a density lower than that of the envelope material. Indeed, if these covers participating in the confinement of the explosive charge 4, the fragments or fragments which they generate do not participate in the effectiveness of the charge lo The covers will therefore be made in order to be as light as possible which will improve the effective mass to total mass ratio of the explosive charge 1. It will thus be possible to produce the covers 3 and 5 in aluminum alloy

  made of titanium or steel, for example stainless steel.

  The choice of envelope material 2 proposed by the invention makes it possible, surprisingly, to ensure a natural fragmentation of the envelope of tungsten alloy in the form of relatively homogeneous fragments of approximately 0.5 grams to 8 grams of mass depending on the alloy used. This last value (8 g) corresponds to a 90 mm load of caliber with a 4 mm thick envelope. Virtually no tungsten dust is

done by the detonation.

  This results in a significant perforating efficiency for 2s the load and an effective mass ratio of the load on

the total mass which is important.

  A number of comparative tests of materials were thus carried out by manufacturing charge envelopes having a mass ratio to be projected onto mass of explosive equal to four. All the envelopes were loaded with 60/40 hexolite (60% hexogene, 40% tolerance). The results of the wind tests summarized in the following table: 3s

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  N of Resilience Elongation Resistance Average mass of material (J / cm2) (%) at the level of the bursts tested rupture generated (in (Mega milligram) Pascal)

1,120 25,935 55

2,320 30 1,060 74

3 10 7 600 <2

4 85 20 720 <2

60 15 730 <2

6 380 35 1020 73

7,200 22 1,150 75

8,200 14 1,300 63

  The envelopes were produced by sintering under isostatic compression of a powder comprising at least 90% of tungsten as well as addition materials and having a density after sintering of between 17 and 18.8. Materials exhibiting such mechanical characteristics can easily be obtained from special industrialists in the sintered tungsten process. It was found that only if the samples present at the same time have a resilience greater than 120 J / cm2, an elongation rate greater than 10% and a tensile strength greater than 930 Mpa make it possible to obtain splinters.

  homogeneous in natural fragmentation.

  IS The average masses of shards of wind are particularly interesting (greater than 70 mg) with alloys having at the same time a resilience greater than 200 J / cm2, a rate of elongation greater than 22% and a resistance to

breaking greater than 1000 Mpa.

  The best wind and sample alloys: N 2 resilience 320 J / cm2, elongation 30%, resistance to

breaking 1060 Mpa.

  N 6 resilience 380 J / cm2 / elongation 35%, resistance to

breaking 1020 Mpa.

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  N 7 resilience 200 J / cm2 F elongation 22% 'resistance to

breaking 1150 Mpa.

  The results obtained are surprising given the teachings of the prior art which propose S projectiles with a tungsten envelope providing a mixture of fragments and tungsten dust and which can bring a blast (or incendiary effect on the fuel tanks) this which is usually the main effect

research with such projectiles.

  In fact, the charges known today and designed to project tungsten flakes with perforating capacity, put your preformed flakes (balls or cubes) placed between two protective envelopes. An internal envelope is in particular necessary to absorb IS the shock wave generated by the explosive and to prevent the

destruction of preformed shards.

  The known loads therefore have complex and costly realization and they have a reduced efficiency by the obligation which is made to absorb the effects of the shockwave on the

preformed chips.

  The shrapnel-generating envelope 2 according to the invention therefore makes it possible to considerably simplify the architecture of the explosive charge. In fact, the envelope is made of a homogeneous material whose reasonable thickness (2 to 8 mm 2s depending on the caliber) allows a significant explosive load and a

optimal efficiency.

  The envelope 2 described in FIG. 1 is here produced in the form of a cylindrical tube of axis 8. Any other envelope geometric would obviously be possible. In particular, the envelope may be produced in the form of a projectile body (for example of large caliber shells or an air / ground bomb) having an aerodynamic external profile. This profile may be in one piece and possibly closed at the level of its part.

before warhead.

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  Figures 2, 3, 4 and 5 show variants of the invention in which we carried out on the envelope 2

  generator of shards a network 9 of lines of weakness.

  FIG. 2 shows a network 9 of weakening lines S obtained by machining grooves on the external surface of the envelope. FIG. 3 shows a network 9 obtained by treatment

  thermal localizes from the outer surface of the envelope.

  Heating or machining will in all cases be carried out according to a network 9 comprising lines: straight lines 10 (parallel to the axis 8 of the load) and circular lines 11 (centered on the axis 8 of the load) (see FIG. 4) or

helicoidales 12 (Figure 5).

  Like. s fragile networks are well known to those skilled in the art. They can also be performed on the

inner surface of the envelope.

  The thermal or mechanical treatment can be carried out by laser, electronic bombardment, surface treatment

localizes (such as carburetion).

  Such a network makes it possible to more precisely control the geometric, therefore the mass of fragments generated by the charge. We can for example refer to patent FR2438686 which describes various methods of weakening envelopes of

steel explosive charges.

  These procedures are adaptable to the envelope load

tungsten according to the invention.

  The parameters of the fragi l i sation will of course be adapted by the skilled person depending on the nature of the material used and the dimensions of the load to be manufactured. It will suffice for a tungsten envelope load according to the invention to achieve embrittlement over a depth

  between 2% and 50% of the thickness of the envelope.

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  In the case of machining, grooves will therefore be made over a depth of between 2% and 50% of the thickness of the envelope. In the case of heat treatment, localized heating will be carried out, causing the material to be annealed over a depth of between 2% and 10% of the thickness of the envelope. Figure 6 shows ammunition incorporating a charge

explosive 1 according to the invention.

  The envelope 2 carries a network 9 of embrittlement by heat or surface treatment and it is closed at each end by a cover 3, 5 This mode of embrittlement is here preferred for machining so as not to degrade the mechanical resistance of the 'casing 2 to flexionO Each cover has a cylindrical bearing surface 13, 15 which receives the casing 2. The casing 2 is made integral with the covers by transverse screws 14 (only the axis is shown here) OL' the axis of the screws is arranged at a distance D from the end of the casing 2 which is greater than or equal to the diameter of the screws, so as not to weaken excessively

  the casing at the level of the fixing screws 14.

  It would also be possible to secure the casing 2 and the covers by laser welding or by brazing. Welding or brazing will be carried out in line with the cylindrical bearings 13 and 15 for example according to the

direction of axes 14.

  We can do this with steel covers

  comprising nickel, for example stainless steel.

  The tungsten alloy also incorporating nickel, the fusion of this element both in the envelope and in the

  cover during laser welding will ensure soldering.

  The ammunition represented in FIG. 6 comprises a front part 16 (which contains for example a seeker and / or a target detector) as well as a rear part 17 which

contains, for example, a propellant.

  The front 16 and rear 17 parts are made integral with the front cover 3, or rear 5 respectively by means of fixing means which are not shown (screwing, welding). In accordance with the invention, the envelope 2 linked to the covers 3 and 5 provides the mechanical connection between the front part 16 and the rear part 17 of the ammunition. The envelope 2 thus alone forms a section of the structure of the body of the munitionO Such an arrangement is made possible thanks to the envelope according to the invention, the mechanical strength (in particular of bending) is sufficient to ensure IS such a connection while ensuring, however, the formation of desired splinters. Furthermore, the rear cover 5 which carries the detonator 6 has a cylindrical bearing surface 15 having the same diameter as the casing 2 and the rear part 17. Thus the axial forces are transmitted directly of envelope 2 a

  the rear part 17 without constraining the rear cover 5.

  It is no longer necessary with the envelope according to the invention to produce an ammunition body ensuring the structural mechanical hold of the ammunition and inside which would be an envelope generating preformed shards. The envelope according to the invention therefore allows the production of ammunition of extremely simple mechanical structure. 1i 2840402

Claims (14)

  1- Enclosure (2) generating generators for explosive charge / envelope characterized in that it is made of a tungsten alloy having a resilience greater than J / cm2, an elongation rate greater than 10% and a   breaking strength greater than 930 Mpa.   2- envelope according to claim 1, characterized in that it is made of a tungsten alloy having a resilience greater than or equal to 200 J / cm2 r an elongation rate greater than or equal to 22% and a resistance to   rupture greater than or equal to 1000 Mpa.   3- The envelope of claim 2, characterized in that it is made of a tungsten alloy having a resilience of 380 J / cm2, an elongation rate of 35% and a   tensile strength of 1020 Mpa.   4- The envelope of claim 2, characterized in that it is made of a tungsten alloy having a resilience of 320 J / cm2, an elongation rate of 30% and a   tensile strength of 1060 Mpa.   - Envelope according to claim 2, characterized in that it is made of a tungsten alloy having a resilience of 200 J / cm2 f an elongation rate of 22% and a   breaking strength of 1150 Mpa.   2s 6- Envelope according to one of claims 1 to 5,   characterized in that it has a thickness of between 2 mm and 8 mm.   7- envelope (2) according to one of claims 1 to 6,   characterized in that it carries a network (9) of lines of embrittlement.   8- envelope according to claim 7, characterized in that the embrittlement (9) is achieved over a depth   between 2% and 50% of the thickness of the envelope (2).   9- Explosive charge (1) burst generator comprising an explosive charge (4) placed in an envelope (2) burst generator as well as at least one initiator (6) for 12 2840402   this loading, charge characterized in that the shell generating (2) flares is made of a tungsten alloy having a resilience greater than 120 J / cm2, an elongation rate greater than 10% and a tensile strength greater than 930 Mpa. - Explosive charge according to claim 9, characterized in that the envelope (2) is made of a tungsten alloy having a resilience greater than or equal to 200 J / cm2, an elongation rate greater than or equal to 22% and   a tensile strength greater than or equal to 1000 Mpa.   11- Explosive charge according to one of claims 9 or   , characterized in that the casing (2) is made of a tungsten alloy having a resilience of 380 J / cm2, an elongation rate of 35% and a breaking strength of 1020 Mpa.   12- Explosive charge according to one of claims 9 or   , characterized in that the casing (2) is made of a tungsten alloy having a resilience of 320 J / cm2, an elongation rate of 30% and a breaking strength of 1060 Mpa.   13- Explosive charge according to one of claims 9 or   , characterized in that the casing (2) is made of a tungsten alloy having a resilience of 200 J / cm2, an elongation rate of 22% and a breaking strength of 1150 Mpa.   14- Explosive charge according to one of claims 9 to 13,   characterized in that the casing (2) generating splinters has   a thickness between 2 mm and 8 mm.   - Explosive charge according to one of claims 9 to 14,   characterized in that the casing (2) generating splinters   carries a network (9) of weakening lines.   16- Explosive charge according to claim 15, characterized in that the embrittlement (9) is carried out over a depth between 2% and 50% of the thickness of the envelope 13 2840402   17- Explosive charge according to one of claims 9 to 16,   characterized in that the envelope (2) is closed by at least one cover- (3j5) having a cylindrical bearing surface (1315) at the level of which it is positioned, cover s of which the envelope is made integral by transverse screws ( 14), by laser welding or by soldering 18- Explosive charge according to claim 17 r characterized in that at least one cover (3,5) is made of a material with a density lower than that of the material of the envelope (2).   19- Explosive charge according to claim 18, characterized in that at least one cover (3,5) is produced Stainless steel.   - Ammunition incorporating an explosive charge (1) according to   one of claims 9 to 19, characterized in that   the cover (2) provides the mechanical connection between a front part (16) and a rear part (17) of the munition forming