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Publication numberUS3205818 A
Publication typeGrant
Publication dateSep 14, 1965
Filing dateAug 2, 1963
Priority dateAug 2, 1963
Publication numberUS 3205818 A, US 3205818A, US-A-3205818, US3205818 A, US3205818A
InventorsCoulson John R
Original AssigneeDu Pont
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Connector for explosive cords
US 3205818 A
Abstract  available in
Images(1)
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Claims  available in
Description  (OCR text may contain errors)

Sept. 14, 1965 J. COULSON CONNECTOR FOR EXPLOSIVE CORDS Filed Aug. 2, 1963 INVENTOR JOHN R. COULSON United States Patent 3,205,818 CONNECTOR FOR EXPLOSIVE CGRDS John R. Coulson, Wayne, NJ., assiguor to E. I. du Pont de Nemours and Company, Wilmington, Del., a corporation of Delaware Filed Aug. 2, 1963, Ser. No. 299,603 4 Claims. (Cl. 102-47) This invention relates to a device for effectively and safely securing a length of low energy connecting cord and a detonating fuse in operative relationship to one another so that a detonation stimulus can be propagated from the fuse to the cord or, conversely, from the cord to the fuse.

Recently, a novel detonation transmitting cord, termed low-energy connecting cord, has been developed. Such cord is described in U.S. Patent 2,982,210 and comprises a continuous core of a detonating explosive, e.g., PETN, RDX, nitromannite, HMX, lead azide, picryl sulfone, etc., at a loading of from 0.5 to 2 grains per foot of length, contained within a sheath of a ductile metal which is subsequently covered with one or more layers of reinforcing and/ or waterproofing material. Due to its ability to propagate a detonation impulse without attendant brisance and because it is free frornthe hazards associated with electric initiators, in many explosive applications, such as blasting operations, this cord has replaced conventional detonating fuse, i.e., Primacord, and electrical initiators. In many applications, it is desirable to use this cord in conjunction with detonating fuse, the low-energy connecting cord being used in sections of the blasting assembly where brisance would be undesirable and the detonating fuse being used where a detonation stimulus of greater magnitude is needed or, in any case, would not be objectionable. In such assemblies, it is necessary to secure the ends of the lengths of the low energy connecting cord and the detonating fuse together in abutting relationship so that the detonation impulse from one detonation-transmitting means, i.e., the fuse or the cord, will be reliably propagated to the other detonation transmitting means. Heretofore the ends have been held in the requisite abutting relationship by metal clips, for example, of the clothespin type, which have not been satisfactory. Not only do clips of this type fail in many cases to hold the cord and fuse in operative arrangement, they provide a unit in which there is a relatively great susceptibility to accidental actuation by stray electric currents and which will shatter to produce undesirable shrapnel upon detonation.

These and other deficiencies are overcome by this invention which provides a connector for explosive cords which comprises a tube of an electrically nonconductive material having at least one open end, a transverse slot intermediate the ends of the tube and communicating with its bore, the walls of the slot providing means for accepting and engaging a first explosive cord in a recessed position in the tube at substantially right angles to its longitudinal axis, and means in said bore for retaining the end of a second explosive cord in said tube in propa gating relationship to said first cord.

In a particularly preferred embodiment of this invention, a booster charge of high velocity detonating explosive is interposed between, and in propagating relationship to, the end of the second cord in the bore of the tube and the slot for the firstcord, the booster charge being adapted to transmit a detonation stimulus from one of said cords to the other.

The term explosive cord as used herein is meant to include both the newly developed low-energy connecting cord and conventional detonating fuse.

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The term transverse slot is intended to require that the slot extend completely across the tube at an angle to its longitudinal axis.

The first cord should be recessed sufiiciently to allow propagation between it and the second explosive cord or between it and a booster charge if a booster charge is required. Although it is not essential in all cases, it is preferred that the exposed core of the second cord be essentially in contact with the wall of the first cord. For example, low energy connecting cord having a core of PETN will pick up the detonation from Primacord if it is flush or nearly flush; however, low energy connecting cord having a core of 2 gr./ft. lead azide will pick up a detonation from a cord having a cord of PETN at a loading of a 4 gr./ft. contained in a sheath of rayon braid and a polyethylene jacket across a space of about one inch.

The parts of the connector may be more clearly illustrated by reference to the accompanying drawings in which:

FIGURE 1 is a view of one form of a connector in accordance with this invention in longitudinal cross section;

FIGURE 2 is a perspective view of the assembly with a length of detonating fuse and a length of connecting cord inserted;

FIGURE 3 is a view in partial cross-section of an alternative embodiment of the connector of this invention;

FIGURE 4 is a view in partial cross-section of still another embodiment of the connector of this invention; and

FIGURE 5 is an enlarged perspective view of the retaining clip in the connector of FIGURE 4.

Referring to the drawings in more detail, in FIGURE 1, 1 is a tube of a nonconductive material having an open extremity A and a closed extremity B. Slot 2 is provided near extremity B and is essentially perpendicular to the longitudinal axis of the shell. The slot is provided with resilient projections 3 and terminates in recessed channel 4- which is here shown as circular and which is adapted to receive detonating fuse transversely therethrough. The bore 5 of the tube 1 proceeds from open extremity A and communicates with channel 4 through opening 6. A booster charge 7 of a high velocity detonating explosive is contained in capsule 16 which is crimped to the end of low energy connecting cord 8 within the shell and is contiguous to opening 6 which corrnnunicates with channel 4 provided for the detonating fuse. As may be seen from the partial cut away view, the low energy connecting cord comprises core 9 of detonating composition, metal sheath l0 and .a countering 11 of a waterproof composition. Shoulder projection 17, which may be one continuous annular projection or a plurality of individual projections, provides means in the bore which permit forceful insertion of capsule 16 from the open end A of tube 1 but resist its withdrawal thereby retaining cord 8 in the bore of tube 1.

In FIGURE 2, the connector of FIGURE 1 is shown with a length of detonating fuse 15 in channel 4 and held in place by projections 3. Low energy connecting cord is contained in bore 5 of tube 1.

In FIGURE 3, the elements are again as in FIGURE 1, however, in this embodiment, both ends of the tube are open and therefore slot 2 is best defined as terminating in two aligned apertures 4a, one at each of its ends. The alignment of these apertures is such that they position the explosive cord, e.g., detonating fuse, with respect to booster capsule 7 in the same manner as channel 4 (FIGURE 1). In addition, slot 2 is angled to provide greater holding power and one or more ribs 19 are provided to insure a snug fit between the booster capsule and the inner wall of tube 1. A thin rib or rudder 2t reinforces the slotted portion of the tube and strengthens the grip of the tubular connector on the detonating fuse. This strengthening also could be accomplished by increasing the wall thickness or by using a more rigid nonconductive material.

In FIGURE 4, the elements are again as in FIGURE 1, however, in this embodiment the booster charge 7 is a pressed pellet contiguous to opening 6 which communicates between bore and channel 4. Clip 12 is provided to engage the low-energy connecting cord with its cut end in propagating relationship to the booster charge 7. The clip has projections 13 which extend from its interior surface and cut into the countering of the low energy connecting cord and an oppositely disposed serrated edge 14 which grips the inner wall of tube 1.

FIGURE 5 is an enlarged perspective view of the clip.

In operation, the low-energy connecting cord is inserted into the bore of the tubular shell so that the cut end of the cord is in propagating relationship to the slot for the detonating fuse, either directly or through booster charge 7. As shown, booster charge 7 can be contained in a capsule which is crimped to the inserted end of the low-energy connecting cord or may be a pressed pellet of an explosive composition. When the booster charge is contained in a capsule, the cord may be forcefully inserted into the bore of the tube past shoulder projections 17 with the capsule containing the booster charge already crimped on the end of the cord. Alternatively, in embodiments where the tube is open at both ends, as in FIGURE 3, the cord is inserted into the bore of the tube past shoulder 17, i.e., the tube may be slipped over the cord, the capsule containing the booster charge crimped on the end of the cord and the capsule positioned in the bore of the tube with the shoulder 17 and the rib I9 retaining the cord in the bore of the tube. The detonating fuse is inserted into slot 2 which preferably is flared for easy insertion of the fuse and is pulled down past resilient projections 3 which retain the fuse in aperture 4. According to the requirements of the blasting assembly, either the detonating fuse or the low-energy connecting cord can be the main line, the other cord then being the branch line. In situations in which the low-energy connecting cord is used as the main line, the detonation impulse is propagated to booster charge 7 by the explosive core 9 of cord 8. When booster charge 7 is initiated, the detonation impulse produced is suflicient to initiate the detonating fuse. On the other hand, if the detonating fuse is the main line, the brisance of this fuse, as a detonation impulse passes through opening 6, initiates the core 9 of cord 8 directly so there is no need for a booster charge.

The connector of this invention is particularly useful in nonelectric delay blasting assemblies which provide insurance from cut offs due to ground movement and also permit bottom hole priming while avoiding the hazards of accidental actuation by stray electric currents, e.g., electrostatic discharges, radio frequency energy, and stray currents encountered with electric initiators. Since shell 1 is of an electrically nonconductive plastic material, there is no danger of accidental, premature initiation of the assembly due to the build-up of charges or instantaneous surges of electricity through the unit. Disintegration of the plastic material of the shell upon detonation of the cords is not hazardous to persons or equipment in the vicinity.

The tubular nonconductive shell which is critical to our invention must have sufficient flexibility to enable the cords to be connected with relative ease yet must be rigid enough to withstand pressures and abrasive action present in blasting operations. Accordingly, plastic materials such as high density polyethylene, polypropylene, acetal resins, polytetrafiuoroethylene, nylon, unplasticized polyvinyl chloride, polystyrene, acrylic polymers, and phenolic resins having characteristics of rigidity, tear resistance, and a flexibility are suitable for use as tube 1. These materials are particularly suitable because of their high resistance to sear and deterioration in outside use. The shell of the connectors can be machined or, preferably, formed by injection molding.

The booster charge present to insure initiation of the receptor charge is a pressed, high velocity detonating explosive, for example a pellet of pressed waxed RDX or a pellet of pressed pentolite or a similar composition. Placing the booster charge in a tubular capsule, which is attached, e.g., by crimping, to the end of the low energy connecting cord, insures against damage to the ends of the cord and maintains a waterproof seal at the ends. The loading of the booster charge will preferably be about 1.5 to 2.0 grains. A booster charge of 1.8 grains of finely divided PETN in a coined bottom shell is particularly preferred.

Many variations of the above described assembly are within the scope of the invention. It is intended therefore to be limited only by the following claims.

What is claimed is:

1. In combination, a connector comprising an electrically-nonconductive tube having a substantially cylindrical bore extending its entire length; a transverse slot for accepting a length of detonating fuse, extending through the side of the tube intermediate its ends in a direction generally normal to the bores longitudinal axis and terminating in two aligned apertures, one at each end of the slot, the alignment being such that a straight line connecting the apertures intersects the longitudinal axis of said bore at substantially right angles, and the Walls of said slot providing resilient projections for positioning and firmly engaging said fuse in said apertures; reinforcing means integral with the exterior surface of said tube opposite said slot and extending in the direction of said longitudinal axis; a single length of low-energy connecting cord extending into said bore through its first end; and a. booster capsule snugly seated in said bore and having an integrally closed extremity contiguous to the side of said apertures nearest the bores said first end, said capsule containing a booster charge at its closed extremity in propagating relationship to the end of said cord in the bore and having its other extremity crimped on said cord; the said first end of the bore being provided with at least one integral projection for abutting the crimped extremity of the capsule and preventing its withdrawal from said first end, said bore being of sufficient diameter from its second end to said projection at its other end to permit insertion of said capsule into the bore through said second end and its passage past the slot until said integrally closed extremity is contiguous to said nearest side of the apertures.

2. The combination of claim 1 wherein the detonating fuse is firmly engaged in said apertures in propagating relationship to said booster charge.

3. In combination, a connector comprising an electrically-nonconductive tube closed at one end and having a substantially cylindrical bore extending through its other end and running part of its length; a transverse slot between said closed end and the internal end of said bore for accepting a length of detonating fuse, said slot extending through a side of the tube in a direction generally normal to the bores longitudinal axis and terminating in a channel which communicates with said bore and intersects said axis at substantially right angles, the walls of said slot providing at least one resilient projection intermediate said channel and the outside surface of the tube for positioning and firmly engaging said fuse in said channel at substantially right angles to said axis; a single length of low-energy connecting cord extending into said bore through its open end; and a booster capsule snugly seated in said bore and having an integrally closed extremity adjacent to the side of said channel nearest the bores open end, said capsule containing a booster charge at its closed extremity in propagating relationship to the end of said cord in the bore and having its other extremity crimped on said cord; the open end of said bore being provided with at least one integral projecting means for permitting forceful insertion of said crimped capsule into the bore, said means abutting the crimped extremity of the inserted capsule and resisting its withdrawal from the bore, and said booster charge within the inserted capsule being in propagating relationship to said channel.

4. The combination of claim 3 wherein the detonating fuse is firmly engaged in said channel in propagating relationship to said booster charge.

References Cited by the Examiner UNITED STATES PATENTS 1,021,934 4/12 Kellogg 102-27 2,587,694 3/52 Chalmers et al 102-27 2,715,365 8/55 Godchaux et a1. 10227 2,952,206 9/60 Becksted 10227 3,020,844 2/62 Miller 10227 FOREIGN PATENTS 741,868 12/55 Great Britain.

SAMUEL FEINBERG, Primary Examiner. SAMUEL W. ENGLE, Examiner.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US1021934 *Aug 3, 1911Apr 2, 1912W B KelloggCap and fuse holder for dynamite cartridges.
US2587694 *Oct 1, 1949Mar 4, 1952Canadian Safety Fuse Company LFuse igniting and connecting device
US2715365 *May 9, 1947Aug 16, 1955Borcher Charles ADemolition firing device
US2952206 *May 10, 1957Sep 13, 1960Austin Powder CoFuse connector
US3020844 *Dec 29, 1958Feb 13, 1962Du PontExplosive device
GB741868A * Title not available
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3342133 *Feb 8, 1965Sep 19, 1967Nitroglycerin AbLow energy cord assemblies
US3426681 *Jun 15, 1967Feb 11, 1969Combustion EngExpansion of tubes into tube sheet by use of explosives
US3455242 *Aug 24, 1967Jul 15, 1969Atlas Chem IndSelf-adjusting detachable fuse clip for cartridges
US3789761 *Feb 2, 1973Feb 5, 1974Us ArmyPropagation transfer arrangement
US3993001 *Aug 18, 1975Nov 23, 1976Tetra Plastics, Inc.Explosive expansion means for attaching tubes to tube sheets
US4112845 *Jul 28, 1976Sep 12, 1978The United States Of America As Represented By The Secretary Of The NavyApparatus for detonating across a gap
US4248152 *Jan 24, 1979Feb 3, 1981E. I. Du Pont De Nemours & CompanyField-connected explosive booster for propagating a detonation in connected detonating cord assemblies containing low-energy detonating cord
US4299167 *Apr 28, 1980Nov 10, 1981E. I. Du Pont De Nemours & Co.Nonelectric delay initiator
US4442776 *Apr 21, 1982Apr 17, 1984The United States Of America As Represented By The Secretary Of The Air ForceDetonator block
US4495867 *Jun 18, 1982Jan 29, 1985E. I. Du Pont De Nemours And CompanyAssembly for initiating explosives with low-energy detonating cord
US4681036 *Jan 7, 1986Jul 21, 1987Bintech (Pty) Ltd.Delay starters
US4714017 *May 4, 1987Dec 22, 1987Cxa Ltd./Cxa LteePyrotechnic variable delay connector
US4815382 *Nov 25, 1987Mar 28, 1989Eti Explosives Technologies International Inc.Connector and detonator/connector assembly for initiating explosive primers with low-energy detonating cord
US5171935 *Nov 5, 1992Dec 15, 1992The Ensign-Bickford CompanyLow-energy blasting initiation system method and surface connection thereof
US5423263 *Apr 1, 1994Jun 13, 1995Dyno Nobel, Inc.Detonator-to-shock tube ignition transfer connector
US5463955 *Feb 8, 1994Nov 7, 1995Ici Canada Inc.Transmission tube connector
US5499581 *May 26, 1994Mar 19, 1996The Ensign-Bickford CompanyMolded article having integral displaceable member or members and method of use
US5524547 *Jun 3, 1994Jun 11, 1996Ici Canada Inc.Signal tube and detonator cord connector
US5594196 *Apr 20, 1995Jan 14, 1997Ireco, Inc.Shock tube surface connector
US5703319 *Oct 27, 1995Dec 30, 1997The Ensign-Bickford CompanyConnector block for blast initiation systems
US5703320 *Jan 18, 1996Dec 30, 1997The Ensign Bickford CompanyConnector for blast initiation system
US5792975 *Oct 26, 1995Aug 11, 1998The Ensign-Bickford CompanyConnector block having detonator-positioning locking means
US6123025 *Dec 1, 1992Sep 26, 2000Orica Explosives Technology Pty Ltd.Low noise, low shrapnel detonator assembly for initiating signal transmission lines
US6513437Apr 28, 2000Feb 4, 2003Orica Explosives Technology Pty Ltd.Blast initiation device
US7699004 *May 16, 2005Apr 20, 2010Maxamcorp, S.A.U.Direct load, detonator-less connector for shock tubes
US8033222 *Sep 26, 2007Oct 11, 2011Dyno Nobel Inc.Line-locking connector clip
US20040055494 *Sep 25, 2002Mar 25, 2004O'brien John P.Detonator junction for blasting networks
US20080257191 *May 16, 2005Oct 23, 2008Jose Maria Ayensa MuroDirect Load, Detonator-Less Connector For Shock Tubes
DE2255106A1 *Nov 10, 1972Jun 7, 1973Nitro Nobel AbVerbindungselement zum zuenden einer niederenergiezuendschnur
EP0015067A1 *Jan 24, 1980Sep 3, 1980E.I. Du Pont De Nemours And CompanyField-connected explosive booster, booster-connector assembly and detonating cord assembly comprising such booster-connector assembly
WO1996011375A1 *Oct 10, 1995Apr 18, 1996Austin Powder CompanyMethod and apparatus for transmission of a detonator initiation to a detonating cord
WO1997015537A1 *Sep 24, 1996May 1, 1997The Ensign-Bickford CompanyConnector block for blast initiation systems
WO2001084070A1 *Apr 27, 2001Nov 8, 2001Orica Explosives Technology Pty LtdBlast initiation device
Classifications
U.S. Classification102/275.4, 102/275.7
International ClassificationF42D1/00, F42D1/04
Cooperative ClassificationF42D1/043
European ClassificationF42D1/04F