FR2641371A1 - DEVICE FOR REMOTELY CUTTING SOLID STRUCTURES BY PROJECTION ORIENTED WITH FLOCKS - Google Patents

Abstract

Device for remote cutting of solid structures by the explosion of a charge 1 and with a projectile 10 in the form of a plate thinned in the center and which is deformed into a ring whose diameter is defined by that of the perimeter 11. Application to cuts of steel or composite plates.

Description

DEVICE FOR REMOTELY CUTTING STRUCTURES

  SOLIDS BY ORIENTED PROJECTIONS OF CRASHES

DESCRIPTION

  The invention relates to a device

  remote cutting of solid structures, in particular

  thick metal plates by projections

oriented flakes.

  A number of documents describe various methods of machining, forming or plating

  o the energy produced by an explosion is exploited.

  It is known for example to put a punch in motion or to project a coating plate on a surface

  to cover it with brazing due to heating.

  We also know the use of hollow charges, where an explosive charge is hollowed out following a conical impression and lined with a projectile.

  Conical envelope shape of the same opening. The implosion

  sion of this cone by detonation of the explosive creates

  a filiform metal jet on the axis of the load.

  This metal jet has the property of perforating thick solid targets over great depths. These hollow charges are mainly used to pierce shields. We see during the trajectory

  that the energy of the explosion makes the projectile

  tick and that its matter is animated with a centripetal component, so that it ends up accumulating in the form of a thin jet on the axis of the trajectory

  and that the cone is nearly abolished.

  The invention aims rather to perforate the target along a closed contour such as circular, which causes greater damage and, in the case of plates, allows cuts to diameters

33 decided by the user.

  The device according to the invention comprises a projectile and an explosive charge located behind the projectile relative to the solid. The projectile is disk-shaped having a perimeter similar to the closed contour, a pierced center and a thickness decreasing from the perimeter to the center; the explosive charge is itself able to produce a wave

  substantially flat shock to the plate.

  The projectile thus possibly has a conical concave face. It can be provided with lines

  less radial or circumferential resistance.

  The explosive charge is advantageously provided with a substantially flat face directed towards the

  projectile and separated from it by a layer of air.

  We will now describe the invention more

  in detail with the aid of the appended figures for illustrative

  tratif and not limiting: - Figure 1 is a diametrical section of an embodiment of the device having a symmetry of revolution; - Figure 2 explains the operation of the device; and - Figures 3 to 6 represent front

various forms for the projectile.

  FIG. 1 distinguishes an explosive charge I of cylindroconic shape having a

  cylindrical part 2 at the front and a truncated part

  conical 3 limited by a rear face 6 at the rear,

  constituting the plane detonation wave generator.

  A detonator 5 is located on the rear face 6. The cylindrical portion 2 is terminated by a flat front face 7; a spacer ring 8 separates it from a projectile 10 in the form of a disk which exactly covers the front face 7. The gaseous layer 9 between the charge 1 and the projectile 10 makes it possible to avoid the almost immediate disintegration of the latter at the time

  of the explosion and is therefore a shock absorber.

  The projectile 10 has an outer perimeter 11 and a bore 12 set on its central portion.

  tral. The thickness of the projectile 10 diminishes

  gressively from perimeter 11 to piercing 12; it is marked Ep and Ec respectively. This can be achieved by building it with a back face 13

  plane and a front face 14 concave and conical.

  Figure 2 shows that following the explosion

  the projectile 10, initially in the form of a disc a- as we have just seen, is deformed by opening as it gets closer to the target,

  here a plate 20 to be cut in a circular outline

  21, to take the shape first of a cone 10b and finally a crown 10c. More specifically, the plane shock wave created by the explosive charge 1 projects the material of the projectile 10 at increasing speed with the proximity of the bore 12, so that the material which was at the beginning in the center comes to the front and finds more animated a

  centrifugal speed which makes it progressively closer to

  The trajectory followed by the points of the perimeter 11. Approximately, for each radial section of the projectile 10, a rotation in the plane of the section around the adjacent portion is observed.

  at the perimeter 11; no bead of material

  Raat. Centrifugal velocity of the points located near

  perimeter 11 is low or zero.

  In a concrete example, it was sought to pierce a steel shield target 40 mm thick. Load I and projectile 10 were placed 1 m from target 20. The load was approximately cylindrical, 150 mm in diameter and composed of 2.5 kg of Octolite. The projectile 10 was also 150 mm in diameter, its thickness Ep was 5 mm and its thickness Ec 2.5 mm. The angle

  C was 20 and the bore diameter was 10 mm.

  A cut-out 21 of nearly 150 mm of dia-

  on the target 20. Many other solutions

tables are of course possible.

  For other digital applications, the results obtained from simulations

  from two-dimensional hydrodynamic computation

  or applying, for example, the usable formula

  for the projection of a projectile by a detonation

  frontal: Up / Uc = (Z-1) / (Z + 1) where Z is equal to the square root of 1+ (32r / 27), where r is the ratio of the local surface density

  of the charge on that of the projectile, perpendicular-

  at the wave front, Uc the detonation velocity

  load and Up the local velocity of the projectile.

  By increasing or on the contrary by decreasing the angle C, it is possible to reduce or on the contrary greatly increase, by several meters for example, the distance

  optimum d of perforation shown in Figure 2.

  This optimum distance d corresponds to the flying distance of the chips from which these

  The last ones are almost aligned in a crown.

  The opening of the projectile 10 can be favored

  rid of them with lines of least resistance (Figure 3). These lines may be radial radii 22 and extend from the perimeter 11 to the central bore 12, or circumferential 23 and extend on a closed curve between the perimeter 11 and the central bore

  12. They may be made by mechanical grooving

  nique, electronic or laser bombardment.

  So far we have spoken of projectiles in the form of circular disks. As shown in FIGS. 4 to 6, the projectile may be in the shape of a non-circular disc: FIG. 4 shows an equilateral triangular projectile 104, the figure is a square 105 projectile, and FIG. 6 is a hexagonal projectile 106. Any irregular polygonal shape

  or not is eligible. All the above description

  dente applies to these projectiles. Their interest is to allow to make cuts following

  closed contours similar to their respective perimeters.

114, 115 and 116.

  The front face of the load 2 may not be perfectly conical and have a slight

  curvature in one direction or the other.

  The method can be used, besides

  the cutting of plates, in particular of

  sites, for the destruction of structural elements

  concrete (dismantling of installations) or of

  for the perforation of the casing of a well as well as to disintegrate around this well the

rocks impregnated with oil.

26 4 1371

Claims (5)

  1. Device for remote cutting of solid structures and in particular for cutting a plate (20) in a closed contour (21) comprising a projectile (10) and an explosive charge (1) located behind the projectile (10) relative to the solid (20), characterized in that the projectile (10) is disk-shaped having a perimeter (11) similar to the closed contour (21), a pierced center (12) and a thinner thickness of the equimeter towards the center,   and in that the explosive charge (1) is capable of pro-   to draw a substantially plane shock wave towards the plate. 2. Device according to claim 1, characterized in that the explosive charge (1) has   a substantially planar face (7) facing the projection   tile (10) and separated from the projectile (10) by a layer of gas (9).   3. Device according to any one of   1 or 2, characterized in that the projection   tile has a concave face 14).   4. Device according to any one of   1 to 3, characterized in that the projection   tile (10) has lines of least resistance   (22) joining the perimeter (11) to the center (12).   5. Device according to any one of   Claims I to 4, characterized in that the projection   tile (10) is provided with lines of weakness (23) with a closed contour between the perimeter (11) and the center (12).