US3342133A - Low energy cord assemblies - Google Patents

Low energy cord assemblies Download PDF

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Publication number
US3342133A
US3342133A US430877A US43087765A US3342133A US 3342133 A US3342133 A US 3342133A US 430877 A US430877 A US 430877A US 43087765 A US43087765 A US 43087765A US 3342133 A US3342133 A US 3342133A
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US
United States
Prior art keywords
cord
low energy
charge
delay
bore
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 - Lifetime
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US430877A
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English (en)
Inventor
Strom Tor Alfons
Wetterholm Gustav Allan
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.)
Nitroglycerin AB
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Nitroglycerin AB
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Filing date
Publication date
Application filed by Nitroglycerin AB filed Critical Nitroglycerin AB
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Publication of US3342133A publication Critical patent/US3342133A/en
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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F42—AMMUNITION; BLASTING
    • F42D—BLASTING
    • F42D1/00—Blasting methods or apparatus, e.g. loading or tamping
    • F42D1/04—Arrangements for ignition
    • C—CHEMISTRY; METALLURGY
    • C06—EXPLOSIVES; MATCHES
    • C06C—DETONATING OR PRIMING DEVICES; FUSES; CHEMICAL LIGHTERS; PYROPHORIC COMPOSITIONS
    • C06C5/00—Fuses, e.g. fuse cords
    • C06C5/06—Fuse igniting means; Fuse connectors

Definitions

  • the invention relates to low energy cord assemblies of the type which comprises a length of cord consisting of a high velocity detonating explosive in the form of a continuous core surrounded by a tubular metal element and at least one layer of insulating material, a booster cap attached to and capping one end of said cord, a blasting cap attached to and capping the other end of the cord, and a cylinder-shaped distance member keeping said other end of the cord spaced from the contents of the blasting cap.
  • a low energy cord assembly of the type described above is known in the art (US. patent specification No. 3,020,844).
  • the cylinder-shaped distance or spacing member is in the form of a thin metal capsule, thus comprising a bottom portion provided with an aperture and a short, externally cylindrical portion integral therewith, this latter portion serving as the distance keeping or spacing member.
  • the metal capsule keeps the end of the detonating cord at a fixed distance from the pyrotechnical delay charge or, in a blasting cap of instantaneous action type, from the priming charge, there will be attained an improved safety against static elect-ricity.
  • the detonation wave can blow out a part of the delay charge in a delay blasting cap and this leads to a great spread of the burning time of various blasting caps, it is desirable also for this reason that the end of the detonating cord should be positioned at a certain distance from the delay charge.
  • cylindrical spacing member elongated with a narrow axial bore having a crossseetion area less than 20 sq. mm, preferably between 12 and 0.75 sq. mm., corresponding to a diameter of 5 to 1 mm. if the bore is circular.
  • a part of the delay charge is placed in the bore of the cylindrical spacing member whereby is obtained that the pyrotechnical charge can, but need not necessarily be pressed in a tube in the form of a so called delay element as is conventional in delay blasting caps with electrical initiation.
  • the delay element of a low energy cord assembly of delay type has the shape of a cylinder with axial bore, the interior of which is occupied by the pyrotechnical charge.
  • the spacing member preferably consists of a separate body, and it may be advantageous to provide a delay charge between the two parts.
  • the spacing member has a length lying within the limits 48 mm.
  • the operative reliability of the low energy cord assembly is improved and a less varying burning time is obtained.
  • the composition of the delay charge can be chosen without paying very much attention to the ignition sensitivity, and this will, among other things, facilitate the manufacture, making it easier to handle the pyrotechnical charge.
  • the cylindrical body according to the invention serving as a distance or spacing member may be made of various materials such as metal, plastic, ceramics, etc.
  • FIG. 1 is a view on a larger scale of a cut-up cord or fuse in a low energy cord assembly
  • FIG. 2 is a section through a low energy cord assembly with a spacing member of conventional design
  • FIG. 3 shows in section one end of a low energy cord assembly with a spacing member according to an embodiment of the present invention
  • FIG. 4 shows, also in section, one end of a low energy cord assembly with a spacing member according to another embodiment of the present invention.
  • the numeral 1 designates a thin core of the explosive pentaerythritol tetranitrate (PETN) having a diameter of about 0.4 mm.
  • PETN pentaerythritol tetranitrate
  • the core is enclosed in a lead tube 2 having an outer diameter of 1.0 mm., and the lead tube is surrounded by two layers of insulating material, the layer 3 nearest to the core consisting of paper, and the outer layer 4 of plastic.
  • the numeral 5 designates a metal shell in a low energy co-rd assembly in which the cord is composed as shown in FIG. 1.
  • the metal shell 5 holds an explosive charge 6, a priming explosive 7 and a pyrotechnical delay charge 8.
  • a spacing member in the form of a metal sleeve 9, the cylindrical outer wall of which rests against the inner wall of the metal shell 10 and the bottom of which is provided with an aperture through which the detonation can continue to the delay charge 8 of the blasting cap.
  • booster cap Attached to and capping the other end of the fuse is a so-called booster cap consisting of a metal shell 10 and an explosive charge 11 of secondary explosive only enclosed therein.
  • the booster cap serves to transmit the detonation from a trunk line -(not shown) consisting of conventional detonating fuse by means of a clamping device 12.
  • FIG. 3 shows a cylindrical body 13 with a bore forming a passage from the end of the detonating core 1 to the delay charge 8 in a delay type blasting cap.
  • the bore is partly occupied by the delay charge.
  • the separate cylindrical spacing body 14 with a narrower bore provides a passage from the end of the detonating core 1 to the delay charge 8.
  • the latter is disposed in a cylinder 15 with a central bore, said cylinder with contents thus constituting a separate delay element.
  • the following test series shows how the spread sinks.
  • the tests were performed with a cylindrical spacing member having a bore diameter of 3 mm. and a bore length of 7 mm.
  • a low energy cord assembly of the type which comprises a length of cord consisting of a high velocity detonating explosive in the form of a continuous core surrounded by a tubular metal element and at least one layer of insulating material, a booster cap attached to and capping one end of said cord, a blasting cap attached to and capping the other end of said cord, and a cylinder-shaped distance body for keeping said other end of said cord spaced from the contents of said blasting cap, the improvement that said distance body is elongated and has an axial bore, the cross section of which is less than about 20 mm. in open communication with said cord.

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  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Prostheses (AREA)
  • Drilling And Exploitation, And Mining Machines And Methods (AREA)
US430877A 1964-02-14 1965-02-08 Low energy cord assemblies Expired - Lifetime US3342133A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
SE1823/64A SE314935B (xx) 1964-02-14 1964-02-14

Publications (1)

Publication Number Publication Date
US3342133A true US3342133A (en) 1967-09-19

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ID=20258894

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US430877A Expired - Lifetime US3342133A (en) 1964-02-14 1965-02-08 Low energy cord assemblies

Country Status (5)

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US (1) US3342133A (xx)
AT (1) AT252773B (xx)
CH (1) CH410738A (xx)
GB (1) GB1085131A (xx)
SE (1) SE314935B (xx)

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3993001A (en) * 1975-08-18 1976-11-23 Tetra Plastics, Inc. Explosive expansion means for attaching tubes to tube sheets
US4060033A (en) * 1976-03-09 1977-11-29 Atlas Powder Company Delay booster assembly
US4060034A (en) * 1976-03-09 1977-11-29 Atlas Powder Company Delay booster assembly
US4215631A (en) * 1971-02-25 1980-08-05 The United States Of America As Represented By The Secretary Of The Navy Sealed pyrotechnic delay
US4350097A (en) * 1980-05-19 1982-09-21 Atlas Powder Company Nonelectric delay detonator with tubular connecting arrangement
US4378738A (en) * 1979-12-19 1983-04-05 Proctor Paul W Electromagnetic and electrostatic insensitive blasting caps, squibs and detonators
US4512538A (en) * 1982-03-04 1985-04-23 Societe Nationale Industrielle Et Aerospatiale Device for maintaining a detonating cord against a transparent aircraft canopy member
US4714017A (en) * 1986-09-26 1987-12-22 Cxa Ltd./Cxa Ltee Pyrotechnic variable delay connector
US5710390A (en) * 1995-08-01 1998-01-20 Ofca; William W. Shock tube initiating system for display fireworks

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NZ208080A (en) * 1983-05-20 1986-10-08 Ici Australia Ltd Connector between detonating cord and low energy impulse propagating tubing

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2707439A (en) * 1954-05-26 1955-05-03 Canadian Ind 1954 Ltd Short interval delay blasting device
US2736263A (en) * 1956-02-28 Blasting explosive device
US2796834A (en) * 1956-03-09 1957-06-25 Canadian Ind Short interval delay blasting device
US3021786A (en) * 1958-07-21 1962-02-20 Du Pont Blasting device
US3106892A (en) * 1961-12-27 1963-10-15 Du Pont Initiator
US3205818A (en) * 1963-08-02 1965-09-14 Du Pont Connector for explosive cords

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2736263A (en) * 1956-02-28 Blasting explosive device
US2707439A (en) * 1954-05-26 1955-05-03 Canadian Ind 1954 Ltd Short interval delay blasting device
US2796834A (en) * 1956-03-09 1957-06-25 Canadian Ind Short interval delay blasting device
US3021786A (en) * 1958-07-21 1962-02-20 Du Pont Blasting device
US3106892A (en) * 1961-12-27 1963-10-15 Du Pont Initiator
US3205818A (en) * 1963-08-02 1965-09-14 Du Pont Connector for explosive cords

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4215631A (en) * 1971-02-25 1980-08-05 The United States Of America As Represented By The Secretary Of The Navy Sealed pyrotechnic delay
US3993001A (en) * 1975-08-18 1976-11-23 Tetra Plastics, Inc. Explosive expansion means for attaching tubes to tube sheets
US4060033A (en) * 1976-03-09 1977-11-29 Atlas Powder Company Delay booster assembly
US4060034A (en) * 1976-03-09 1977-11-29 Atlas Powder Company Delay booster assembly
US4378738A (en) * 1979-12-19 1983-04-05 Proctor Paul W Electromagnetic and electrostatic insensitive blasting caps, squibs and detonators
US4350097A (en) * 1980-05-19 1982-09-21 Atlas Powder Company Nonelectric delay detonator with tubular connecting arrangement
US4512538A (en) * 1982-03-04 1985-04-23 Societe Nationale Industrielle Et Aerospatiale Device for maintaining a detonating cord against a transparent aircraft canopy member
US4714017A (en) * 1986-09-26 1987-12-22 Cxa Ltd./Cxa Ltee Pyrotechnic variable delay connector
US5710390A (en) * 1995-08-01 1998-01-20 Ofca; William W. Shock tube initiating system for display fireworks

Also Published As

Publication number Publication date
CH410738A (fr) 1966-03-31
AT252773B (de) 1967-03-10
GB1085131A (en) 1967-09-27
SE314935B (xx) 1969-09-15

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