EP0055165B1 - Procédés et dispositifs pyrotechniques de découpage sous l'eau au moyen d'un cordeau détonant - Google Patents

Procédés et dispositifs pyrotechniques de découpage sous l'eau au moyen d'un cordeau détonant Download PDF

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Publication number
EP0055165B1
EP0055165B1 EP19810401970 EP81401970A EP0055165B1 EP 0055165 B1 EP0055165 B1 EP 0055165B1 EP 19810401970 EP19810401970 EP 19810401970 EP 81401970 A EP81401970 A EP 81401970A EP 0055165 B1 EP0055165 B1 EP 0055165B1
Authority
EP
European Patent Office
Prior art keywords
cavity
cord
pressure
sheath
sealed
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
EP19810401970
Other languages
German (de)
English (en)
French (fr)
Other versions
EP0055165A1 (fr
Inventor
Jacques Sala
René Chagneau
Jean-Claude Russo
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Direction General de lArmement DGA
Original Assignee
Delegation Generale pour lArmement
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Filing date
Publication date
Application filed by Delegation Generale pour lArmement filed Critical Delegation Generale pour lArmement
Publication of EP0055165A1 publication Critical patent/EP0055165A1/fr
Application granted granted Critical
Publication of EP0055165B1 publication Critical patent/EP0055165B1/fr
Expired legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
    • B63C—LAUNCHING, HAULING-OUT, OR DRY-DOCKING OF VESSELS; LIFE-SAVING IN WATER; EQUIPMENT FOR DWELLING OR WORKING UNDER WATER; MEANS FOR SALVAGING OR SEARCHING FOR UNDERWATER OBJECTS
    • B63C11/00—Equipment for dwelling or working underwater; Means for searching for underwater objects
    • B63C11/52—Tools specially adapted for working underwater, not otherwise provided for
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B26—HAND CUTTING TOOLS; CUTTING; SEVERING
    • B26F—PERFORATING; PUNCHING; CUTTING-OUT; STAMPING-OUT; SEVERING BY MEANS OTHER THAN CUTTING
    • B26F3/00—Severing by means other than cutting; Apparatus therefor
    • B26F3/04—Severing by squeezing
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F42—AMMUNITION; BLASTING
    • F42B—EXPLOSIVE CHARGES, e.g. FOR BLASTING, FIREWORKS, AMMUNITION
    • F42B3/00—Blasting cartridges, i.e. case and explosive
    • F42B3/08—Blasting cartridges, i.e. case and explosive with cavities in the charge, e.g. hollow-charge blasting cartridges

Definitions

  • the present invention relates to pyrotechnic methods and devices for cutting under water by means of a detonating cord of the linear hollow charge type.
  • the technical sector of the invention is that of the manufacture of pyrotechnic cutting devices.
  • Detonating cords which are intended to perform linear cutting of metallic structures in an aerial environment. These cords are composed of a malleable tight sheath, for example a sheath of a lead alloy, which contains a continuous pyrotechnic charge.
  • This sheath has a well-defined cross section, generally trapezoidal or triangular in shape and it delimits an open cavity on the side of the base which is applied against the surface of the part to be cut.
  • the covering of this cavity has a geometric shape such that the detonation of the pyrotechnic charge projects it towards the axis in two parts, a metal core and a dart-shaped jet, which cuts the object against which the cord is applied, for example a sheet.
  • the cords have a great flexibility which makes it possible to conform them to make them follow the most diverse lines or contours. Their implementation is very easy since they can be cut into sections of desired length, using a knife.
  • a field of application in which the use of detonating cords is particularly advantageous is that of cutting under water, for example cutting of wrecks, metal structures or submerged pipes, or cutting for military purposes.
  • French patent 2 321 680 describes such a cord in which the pyrotechnic charge is enclosed in a metal sheath containing partitions made of folded sheet metal.
  • Such a cord comprising a metal sheath is suitable for rectilinear cuts but does not allow cuts to be made on curved surfaces, in particular tube cuts, or cuts following a complex contour.
  • British patent 2,026,923 describes a detonating cord intended to cut tubes.
  • This cord comprises two semicylindrical parts which can be joined using appropriate means.
  • Each part includes a detonating cord and an envelope in which the explosive charge is conventionally housed.
  • a rubber membrane is sealingly bonded to the edges of the envelope to delimit with the covering of the load a cavity closed at the ends in a leaktight manner. This cavity can be pressurized.
  • French Patent 2,377,019 describes a detonating cord usable underwater, comprising an envelope in which the explosive charge is placed; the edges of the envelope are extended on the side of the coating of the load to delimit a cavity in which an inflatable envelope is placed.
  • the inflatable envelope consists of two sub-envelopes, one internal in rubber and the other external in abrasion-resistant material.
  • An objective of the present invention is to provide cutting means intended more particularly for work underwater, which have the same ease of implementation as the aerial cutting lines.
  • Another object of the present invention is to provide cutting cords which can be obtained easily, by a relatively simple transformation of aerial cords as found in trade, without the need for any special manufacture.
  • underwater cords as proposed in the patents analyzed above.
  • a pyrotechnic device for making cuts underwater, is of the known type comprising a detonating cord composed of a malleable sheath which contains a continuous pyrotechnic charge and which delimits an open cavity whose opening is intended for be applied against a surface to be cut.
  • detonating cords which further comprise a flexible and waterproof envelope made of a film of heat-shrinkable plastic, which forms a cover stretched across said opening and which defines, with said sheath, a sealed cavity and means for placing said sealed cavity in communication with a source of compressed gas whose pressure is equal to or slightly greater than the hydrostatic pressure at the immersion depth.
  • the sealed cavity which is delimited by the sheath and by 1 1 stretched heat-shrinkable film is connected to a source of compressed gas by means of a pressure reducer which maintains said sealed cavity under pressure or at slight overpressure with respect to the hydrostatic pressure at the depth of immersion.
  • the invention results in the possibility of performing linear cuts underwater by means of detonating cords, which can be of a common type, thanks to a transformation of these which is easy to carry out without having to resort to a special manufacturing.
  • the cords transformed according to the invention have the same malleability as the cords intended for work in the open air and they therefore allow cuts to be made on curved surfaces, in particular tube cuts even if they have a low radius of curvature. They also allow cuts to be made following sinuous contours.
  • An advantage of the cords according to the invention lies in the fact that they employ simple or common means in the field of diving. It is very easy to obtain heat-shrinkable plastic sheaths and to turn them on by heating them with a hot air generator.
  • the sealed cavity which is delimited by the sheath of the cord and by the stretched film of heat-shrinkable plastic material can be pressurized or slightly overpressured using compressed air bottles and a pressure reducer of the type used by scuba divers, that is to say a very common material on submarine sites.
  • Fig. 1 shows a cross section of a device which is composed of a cord 1 of a common type which is found commercially.
  • This cord comprises a malleable sheath 2, for example a sheath of a lead alloy which is generally an alloy of lead and antimony.
  • the sheath 2 contains a continuous pyrotechnic charge 3.
  • This charge consists for example of cyclotrimethylenetrinitramine (hexogen).
  • the weight of the explosive charge varies for example between 2.2 and 60 grams per linear meter and the cutting capacity of a mild steel sheet varies between 1.6 mm and 8 mm thick.
  • the sheath 2 has, in cross section, a well-defined shape which is a general triangular or trapezoidal shape delimiting an open cavity 4, the opening of which is applied against the surface of a piece to be cut 5.
  • This cavity 4 is delimited by walls 2a which are part of the sheath 2 and which have a geometric shape such that the detonation of the pyrotechnic charge 3 projects at very high speed, towards the axial plane x x1, in two parts, a core metallic and a dart-shaped jet which cuts piece 5 along a line.
  • the cavity 4 keeps the geometric shape provided by the manufacturer and that it remains full of air so that the cutting takes place and we cannot therefore use these detonating cords as they are under water because the cavity 4 would fill with water.
  • the cords according to the invention intended for underwater work are coated in a flexible and waterproof envelope 6 in a heat-shrinkable plastic material.
  • This envelope is for example a tubular sheath of the same type as that which is used to sheath the electric or telephone cables, having a sufficient diameter so that the cord can easily be engaged in the sheath over the entire necessary length.
  • the envelope is heated to a temperature sufficient to make it shrink.
  • the retraction temperature is for example of the order of 175 °.
  • the shrinkage operation of the envelope is carried out for example by moving a hot air generator all along the envelope.
  • the movement is fast enough for the temperature rise of the pyrotechnic charge to remain below 50 ° C, which is significantly lower than the critical temperature of the pyrotechnic charge which is of the order of 180 ° C.
  • the cover 6a fulfills several functions. First, it forms part of the sealed sheath 6 and it prevents water from entering the cavity 4. Then, it constitutes a flat surface whose thickness is small, of the order of a millimeter, of such that the presence of the cover 6a between the cord and the part 5 does not substantially modify the relative geometrical arrangement of the cord relative to the surface of the part 5.
  • the cover 6a which is a relatively thin film having a thickness of the order of 0.6 to 1 mm, could not withstand the hydrostatic pressure when the cutting to be carried out is at an immersion depth which exceeds a few meters .
  • a device according to the invention further comprises means shown diagrammatically in FIG. 2 to maintain the cavity 4 in equipression with the outside or, preferably, in slight overpressure, which has the advantage of avoiding the risk of water entering the cavity.
  • These means preferably consist of compressed gas cylinders 7, for example bottles of the type used for scuba diving, which are equipped with a two-stage regulator 8a and 8b, the stage 8b being a differential pressure regulator which delivers a gas which is constantly maintained in slight overpressure with respect to the hydrostatic pressure, for example at a pressure which exceeds the hydrostatic pressure by approximately 40 millibars.
  • the outlet of the regulator 8b is connected by a flexible tube 9 to a metal end piece 10, which is held by a heat-shrinkable sleeve 11, on one end of the cord, so that the tube 9 communicates with the cavity 4.
  • a metal end piece 10 which is held by a heat-shrinkable sleeve 11, on one end of the cord, so that the tube 9 communicates with the cavity 4.
  • the divers responsible for placing the detonating cord on a piece to be cut descend with a cord already connected to bottles, so that the regulator 8b maintains in the cavity 4, throughout the descent, a pressure substantially equal to the pressure hydrostatic which varies with the depth of immersion.
  • the detonating cord can be isolated, for example by means of a tap or a sealed valve connector 19, placed on the flexible pipe 9, which allows the bottles 7 to be moved away before firing the cord and recovering the pressurization assembly.
  • the end piece 10, 11 is located at one end of the cord and the other end is closed in leaktight manner by a cap 12 made of heat-shrinkable and self-sealing plastic material.
  • the connector 10, 11 could also be located not at one end of the cord, but at an intermediate point.
  • an initiating device which is composed of a support in the form of a clamp or of clips 13, the cross section of which takes the shape of the cord and which is pinched thereon.
  • This support comprises a cylindrical sheath 14 in which a detonator 15 is engaged which is connected by wires 16 to an exploder or to an electric generator.
  • This priming device can be quickly installed on the cord at the last moment, in order to avoid handling a primed charge.
  • FIG. 1 Also shown in FIG. 1 a device for fixing the cord on the piece to be cut, which is composed of metal hooks 17 held on the cord by a heat-shrinkable sleeve 18.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Ocean & Marine Engineering (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Forests & Forestry (AREA)
  • General Engineering & Computer Science (AREA)
  • Air Bags (AREA)
  • Perforating, Stamping-Out Or Severing By Means Other Than Cutting (AREA)
EP19810401970 1980-12-15 1981-12-10 Procédés et dispositifs pyrotechniques de découpage sous l'eau au moyen d'un cordeau détonant Expired EP0055165B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8026516 1980-12-15
FR8026516A FR2495991A1 (fr) 1980-12-15 1980-12-15 Procedes et dispositifs pyrotechniques de decoupage sous l'eau au moyen d'un cordeau detonant

Publications (2)

Publication Number Publication Date
EP0055165A1 EP0055165A1 (fr) 1982-06-30
EP0055165B1 true EP0055165B1 (fr) 1984-05-16

Family

ID=9249064

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19810401970 Expired EP0055165B1 (fr) 1980-12-15 1981-12-10 Procédés et dispositifs pyrotechniques de découpage sous l'eau au moyen d'un cordeau détonant

Country Status (3)

Country Link
EP (1) EP0055165B1 (enrdf_load_stackoverflow)
DE (1) DE3163683D1 (enrdf_load_stackoverflow)
FR (1) FR2495991A1 (enrdf_load_stackoverflow)

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2789918B1 (fr) 1999-02-19 2001-06-08 Lacroix Soc E Dispositif de rupture controlee d'une structure travaillant a la traction et equipement en faisant application
FR2806342B1 (fr) 2000-03-15 2002-08-09 Lacroix Soc E Dispositif pour la rupture controlee sans choc de structures
RU2247935C2 (ru) * 2003-03-20 2005-03-10 ООО "Самаратрансгаз" Способ резки прочных конструкций шнуровым кумулятивным зарядом
FR2925955A1 (fr) * 2007-12-26 2009-07-03 Nexter Munitions Sa Cordeau de decoupe pyrotechnique et procede de fabrication d'un tel cordeau

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2067874A5 (en) * 1969-11-19 1971-08-20 Europ Propulsion Detonating fuse for cutting under water
FR2106860A5 (enrdf_load_stackoverflow) * 1970-09-25 1972-05-05 Europ Propulsion
FR2321680A1 (fr) * 1974-01-07 1977-03-18 Poudres & Explosifs Ste Nale Dispositif pyrotechnique de decoupage a effet de charge creuse
AT341401B (de) * 1974-05-10 1978-02-10 Hagenuk & Co Gmbh Wasserdichte, koppelbare schneidladung
GB1556859A (en) * 1976-11-29 1979-11-28 Ici Ltd Shaped explosive charge device for underwater use
GB2026923A (en) * 1978-08-02 1980-02-13 Vickers Ltd Improvements in or relating to explosive devices

Also Published As

Publication number Publication date
FR2495991B1 (enrdf_load_stackoverflow) 1984-10-05
EP0055165A1 (fr) 1982-06-30
FR2495991A1 (fr) 1982-06-18
DE3163683D1 (en) 1984-06-20

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