AU2003264628B2

AU2003264628B2 - Jet-forming Charge

Info

Publication number: AU2003264628B2
Application number: AU2003264628A
Authority: AU
Inventors: Joel Ferron; Henri Ropars
Original assignee: TDA Armements SAS
Current assignee: TDA Armements SAS
Priority date: 2002-12-13
Filing date: 2003-12-01
Publication date: 2009-12-03
Anticipated expiration: 2023-12-01
Also published as: EP1429107B1; FR2848657A1; FR2848657B1; DE60331038D1; AU2003264628A1; EP1429107A1

Description

S&F Ref: 657980 AUSTRALIA PATENTS ACT 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT Name and TDA Armements SAS Address 45 rue de villiers of Applicant: 92526 Neuilly Sur Seine France Actual Henri Ropars Inventor(s): Joel Ferron Address for Spruson & Ferguson Service: St Martins Tower Level 35 31 Market Street Sydney NSW 2000 (CCN 3710000177) Invention Title: Jet-forming Charge The following statement is a full description of this invention, including the best method of performing it known to me/us:- -1 Jet-forming charge The present invention relates to a jet-forming charge. It applies in particular to charges placed in munitions 5 which work by overflying their objective. Jet-forming charges (also known by the name of shaped charges or explosively formed penetrators (EFPs)) are explosive warheads containing a liner set in motion by 10 the detonation of an explosive warhead charge placed in a confinement (also known by the name of envelope) generally cylindrical and made of metal. The liner deforms to form a jet, projected at a speed of the order of 2000 m/s towards a target. Such charges are 15 used to form the warheads of munitions. They are also used in industry (boring, mining works, etc.). The general operating principles of the charges are described in the document "Fundamentals of Shaped Charges" by W.P. Walters and J.A. Zukas (Publisher: 20 CMCPress, ISBN: 0-471-62172-2). Armoured targets are most particularly vulnerable at their upper parts, and this is why attempts are being made at defining munitions with jet-forming charges 25 whose direction of action is more or less vertical. Patent FR2771166 describes, for example, a munition which acts by overflying the objective and which has a warhead whose direction of action is more or less 30 normal to the axis of the munition (that is to say more or less the direction of flight of the munition. The munition contains a jet-forming charge whose confinement is of more or less cylindrical shape. The liner is arranged in such a way that the direction in 35 which it is projected is perpendicular to the axis of the cylinder. One disadvantage of this solution is that the position of the liner with respect to the confinement does not 2 allow effective use of all of the explosive present in the confinement. This is the case in particular of the explosive around the periphery of the liner, the detonation of which plays no part in projecting the jet. Furthermore, the jet formed may break up into several pieces. 5 Object of the Invention It is the object of the present invention to substantially overcome or ameliorate one or more of the disadvantages of the prior art. Summary of the Invention 10 The present invention provides ajet-forming charge comprising: a confinement and a liner adapted to form a jet, wherein: the confinement generally forms a tube having an axis, the tube being open at one end, the tube having a cross section perpendicular to the axis, said cross-section falling within a rectangle having a short side and a long side, said sides being is perpendicular to the axis of the tube, the length of the confinement along the axis and the length of the short side of the rectangle being such that the confinement can be housed within a cylinder having an axis parallel to the long side of the rectangle; and wherein the liner closes the open end of the confinement in such a way that the jet formed by detonation is set in motion in a direction generally parallel to the axis of the tube. 20 One of the main advantages of the invention is that, for a given calibre of munition, it is possible to define a charge the volume of which is not limited by this calibre. The invention makes it possible, by increasing the amount of explosive and the mass of the liner, to obtain ajet that performs better than the jet of an axisymmetric jet forming charge housed similarly in the munition. In addition, this geometry makes it 25 easier to produce warhead charges the characteristics of which observe the planes of symmetry of the charge, particularly for producing warhead charges by casting or compression. The void left between the confinement and the structure of the munition can be used to house electronic modules or for the passage of electrical cables. Preferably, the length of the short side of the rectangle is substantially equal to 30 the length of the confinement along the axis of the tube. Preferably, the cross section of the tube is generally in the form of an ellipse. Preferably, the liner has two perpendicular planes of symmetry, and the intersection of said two planes forms the axis of the tube. Preferably, the liner has at least one concave face. 35 Preferably, the concave face of the liner is spherical or toric or ellipsoidal.

3 Preferably, the mean value of the radius of curvature of the concave face of the liner is within of plus or minus 20% of a nominal radius, said nominal radius being equal to twice the length of the tube along the axis of the tube. Preferably, the jet-forming charge further includes initiators placed on a surface s of the confinement facing the liner. Preferably, the jet-forming charge further includes initiators distributed symmetrically with respect to the planes of symmetry of the liner.

According to one advantageous embodiment, there are four initiators. Other features and advantages of the invention will 5 become apparent from the description which follows, given with reference to the attached drawings: - Figures 1 to 3 depict an example of a munition comprising a charge according to the invention in a side view, a view from above, and a radial view, 10 respectively; - Figure 4 depicts a horizontal section of the confinement; - Figures 5 to 8 depict an example of a charge according to the invention viewed in isometric 15 perspective, in an axial view (along the axis of the munition), viewed from above and viewed from the side, respectively; - Figure 9 depicts the liner in an isometric perspective view. 20 Reference is now made to Figures 1 to 3 which depict an example of a munition comprising a charge according to the invention. The munition 2 has a body essentially cylindrical with respect to an axis of symmetry 3. The 25 axis of symmetry 3 is more or less horizontal, aligned with the direction of travel of the munition when it is in flight. The munition 2 contains a charge 1 placed inside it. This charge has a direction of action 4 that is more or less vertical, that is to say perpendicular 30 to the axis of symmetry 3. Reference is now made to Figure 4. The charge 1 comprises a confinement 5 in which an explosive warhead charge (not depicted) is placed. The confinement may be 35 made of steel, aluminium or plastic for example. The charge further comprises at least one initiator (not visible in this figure) intended to initiate detonation of the explosive warhead charge. The confinement 5 has an opening closed by a liner 6. The liner is intended to form a jet when the explosive warhead charge is detonated. The liner may be. made of metal, such as tantalum, nickel, iron or copper for example. Advantageously, when the charge is placed in the 5 munition, the liner is on one side of the munition, within the exterior profile of the munition and flush with the latter in its outermost parts. The confinement more or less forms a tube along the 10 axis 4. The tube has, in the horizontal plane (the plane perpendicular to the axis 4) a cross section that falls within a rectangle 7. Advantageously, the section of the tube is an ellipse or almost an ellipse. The rectangle 7 has a long side 8 and a short side 9 of 15 different lengths. The long side 8 is parallel to the axis 3. As the confinement is housed in the munition 2, its length along the axis 4 and the length of the short side 9 are limited by the calibre of the munition 2. In other words, the length of the confinement along the 20 axis 4 and the length of the short side of the rectangle are such that the confinement can be housed in a cylindrical tube (portion of munition) the axis of which is parallel to the long side 8. 25 According to an advantageous embodiment, in order to maximize the useful volume of the charge for a given calibre of the munition, the length of the short side 9 is more or less equal to the length of the confinement along the axis of the tube 4. 30 Reference is now made to Figures 5 to 8. According to one advantageous embodiment, the liner has two planes of symmetry 10 and 11. These planes of symmetry are perpendicular and their intersection forms the axis of 35 the tube (axis 4). The initiators 12 may be four in number, and be positioned on the face of the confinement 5 situated facing the liner 6 symmetrically with respect to the -6 planes of symmetry 10, 11 of the liner. The liner may itself be symmetric with respect to the planes 10, 11. Thus, the explosive warhead charge detonates, forming a wave that is symmetric with respect to the planes 10, 5 11. As the liner is itself symmetric with respect to the planes 10, 11, there is obtained a jet that propagates along the axis 4 and is symmetric with respect to the planes 10, 11. 10 Reference is now made to Figure 9. According to an advantageous embodiment, the liner has at least one concave face 15. The other face of the liner 16 may be planar or convex (if the liner has a constant thickness for example) . The concave face 15 of the liner is 15 advantageously spherical, toric or ellipsoidal. Advantageously, the mean value of the radius of curvature 14 of the concave face 15 of the liner is equal to twice the length of the tube along its axis 4, 20 give or take 20%. Advantageously, the liner contains the entire cross section of the tube. In this example it therefore has a projection in a horizontal plane (plane perpendicular 25 to the axis 4) that has the shape of an ellipse 13. This makes it possible not only to form a jet more efficiently, but also makes it possible to have an area of contact between the liner and the confinement which is not limited by the thickness of the confinement 30 (contact is with the interior surface of the confinement rather than with an edge of the confinement). Of course the invention is not restricted to this 35 exemplary embodiment. The number of initiators may differ. The liner may have a variable thickness.

Claims

1. Jet-forming charge comprising: a confinement and a liner adapted to form a jet, wherein: 5 the confinement generally forms a tube having an axis, the tube being open at one end, the tube having a cross section perpendicular to the axis, said cross-section falling within a rectangle having a short side and a long side, said sides being perpendicular to the axis of the tube, the length of the confinement along the axis and the length of the short side of the rectangle being such that the confinement can be housed 10 within a cylinder having an axis parallel to the long side of the rectangle; and wherein the liner closes the open end of the confinement in such a way that the jet formed by detonation is set in motion in a direction generally parallel to the axis of the tube.

2. Jet-forming charge according to Claim 1, wherein the length of the short side of the rectangle is substantially equal to the length of the confinement along the axis is of the tube.

3. Jet-forming charge according to any one of the preceding claims, wherein the cross section of the tube is generally in the form of an ellipse.

4. Jet-forming charge according to any one of the preceding claims, wherein the liner has two perpendicular planes of symmetry, and the intersection of said 20 two planes forms the axis of the tube.

5. Jet-forming charge according to any one of the preceding claims, wherein the liner has at least one concave face.

6. Jet-forming charge according to Claim 5, wherein the concave face of the liner is spherical or toric or ellipsoidal. 25

7. Jet-forming charge according to Claim 5 or 6, wherein the mean value of the radius of curvature of the concave face of the liner is within of plus or minus 20% of a nominal radius, said nominal radius being equal to twice the length of the tube along the axis of the tube.

8. Jet-forming charge according to any one of the preceding claims, further 30 including initiators placed on a surface of the confinement facing the liner.

9. Jet-forming charge according to Claim 4, further including initiators distributed symmetrically with respect to the planes of symmetry of the liner.

10. Jet-forming charge according to Claim 9, wherein there are four initiators. 8

11. A jet-forming charge substantially as hereinbefore described with reference to any one of the embodiments as that embodiment is shown in the accompanying drawings. 5 Dated 28 October 2009 TDA Armements SAS Patent Attorneys for the Applicant/Nominated Person SPRUSON & FERGUSON