US3657958A

US3657958A - Safe-armed explosive initiation device

Info

Publication number: US3657958A
Application number: US865702A
Authority: US
Inventors: John L Wells
Original assignee: Explosive Technology Inc
Current assignee: Explosive Technology Inc
Priority date: 1969-10-13
Filing date: 1969-10-13
Publication date: 1972-04-25
Anticipated expiration: 1989-04-25

Abstract

A safe-armed explosive initiation device carried in a housing and defined by a firing mechanism, a donor charge pivotally mounted within the housing and normally held out of alignment with the firing mechanism, spring means for moving the donor charge into alignment with the firing mechanism upon actuation of the firing mechanism, and an acceptor charge positioned in line with the donor charge when the latter is pivoted to the armed firing position.

Description

United States Patent [151 3,657,958

Wells 51 Apr. 25, 1972 54] SAFE-ARMED EXPLOSIVE INITIATION 2,845,002 7/1958 Ackermann, Jr. et a1 ..s9/1 a DEVICE 3,129,663 4/1964 Schnepfe, Jr. ...|02/70 x 3,386,334 6/1968 Temple et a1 ..89/] B [72] Inventor: John L. Wells, Vacavrlle, Calif.

1 I i T h l I F 1d, Primary Examiner-Samuel W. Engle [73 1 Ass'gnee 222: Attorney-Flehr, Hohbach, Test, Albritton & Herbert [22] Filed: Oct. 13, 1969 [57] ABSTRACT [21] Appl. No.: 865,702 A safe-armed explosive initiation device carried in a housing and defined by a firing mechanism, a donor charge pivotally mounted within the housing and normally held out of align- [52] US. Cl ..89/l B, 102/27, 102/76 ment with the firing mechanism p g means for moving the l Cl "F42b 3/10 donor charge into alignment with the firing mechanism upon [58] Fleld of Search 89/1, 1 B; 102/70, 27,78, actuation of the firing mechanism and an acceptor charge 5 1 positioned in line with the donor charge when the latter is pivoted to the armed firing position.

[56] References Cited 9 Claims, 4 Drawing Figures UNITED STATES PATENTS 2,709,962 6/1955 Funk, Jr. et a1 102/78 BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to the field of safe-armed explosive initiation devices in which a donor charge is initially and normally located in an inoperative position when the device is in a safe condition and in whichthe donor charge is automatically located in an operative position upon actuation of the firing mechanism of the device so that, upon firing of the donor charge, an acceptor charge located adjacent thereto is activated to propogate a controlled detonation. More specifically, this invention relates to the field of one-way explosive transfer devices in which an initially unarmed device is automatically armed and fired in rapid sequence upon actuation of the firing mechanism of the device.

2. Description of the Prior Art So far as is known, asafe-armed explosive initiation device of the type disclosed herein has not been utilized in the art heretofore. While explosive transfer safe-armed devices have been generally known heretofore, the particular construction disclosed herein, in which a movable donor charge is normally held in an inoperative safe orientation to be subsequently oriented automatically to an armed orientation upon actuation of a firing mechanism, has been unknown heretofore.

The present device is extremely safe in that it is constructed so that the same cannot detonate in the presence of fire, rough handling, or. the like. Also, the present device is fast acting and automatic and may be rapidly changed from the unarmed to the armed condition upon the firing mechanism being actuated. Thus, the present device has the important safety features essential in a detonating device coupled with fast acting characteristics which adapt such a device for the varied uses in which safe-armed mechanisms are normally employed. The present device is designed to be inexpensively produced from readily available materials and is embodied in a simple yet substantially fool-proof automatic system which is easy to operate.

The present device requires only a single actuation of the firing mechanism, in contrast to prior known safe-armed devices which require two or more distinct manuevers or functions before they complete their intended purpose. That is, the present device effects both arming and detonating operations in rapid sequence in response to actuation of the firing mechanism.

SUMMARY OF THE INVENTION The present safe-armed explosive initiation device is embodied in a simple yet fool proof and inexpensive construction in which a donor charge is normally held out of alignment with a firing mechanism when the device is in the unarmed condition with the donor charge being automatically oriented to arm the device upon actuation of the firing mechanism. When in the latter position, the donor charge is interposed between and aligned with a firing pin and an acceptor charge so that detonation of the donor charge by the firing mechanism produces detonation of the acceptor charge, the latter then performing any desired function for which explosive transfer devices of the subject type are commonly utilized.

From the foregoing, it should be understood that objects of this invention include the provision of an improved safearmed explosive detonation transfer device; the provision of such a device in which a donor charge may be automatically positioned to detonate an acceptor charge; the provision in a safe-armed device of a movable donor charge normally held out of alignment with the firing pin of a firing mechanism; the provision of selectively and automatically alignable donor and acceptor charges in a safe-armed one way explosive transfer device; the provision of a safe-armed explosive initiation device in which a normally unarmed device is automatically armed and fired in response to movement of the firing mechanism of the device; and the provision of a safe-armed device which may be recharged for reuse after detonation.

These and other objects of this invention will become apparent from a study of the following disclosure in which reference is directed to the appended drawings.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal sectional view of the subject safearmed device showing the same in the safe, unarmed condition.

FIG. 2 is a sectional view corresponding generally to FIG. 1 showing the device in the armed, ready for firing condition.

FIG. 3 is a transverse sectional view through the device taken in the plane of line 33 of FIG. 1.

FIG. 4 is an isometric view of the carrier casing for the donor charge of the subject device.

DESCRIPTION OF THE PREFERRED EMBODIMENT The subject safe'armed explosive initiation device, generally designated 1, is self-contained and is defined by a generally cylindrical housing 2, formed of a suitable metal such as aluminum,'which in the embodiment illustrated is circular in transverse cross-sectional configuration. The housing has an elongated enlarged bore 3 therein extending from one end thereof which imparts a substantially hollow configuration to the housing. The bore extends for substantially the full length of the housing and terminates adjacent the opposite end in an internal shoulder 4.

At its first mentioned end, bore 3 is provided with internal threads 6 by means of which an elongated cylindrical metal fitting 7, of aluminum or other suitable metal, is threadedly received within the bore. The fitting defines a carrier for the explosive initiation mechanism of the device. At its inner end 8, fitting 7 contacts the seat 4 defined by the inner end of the bore as seen in FIG. 1. For the purpose to be described hereinafter, the inner end of the fitting is provided with a pair of diametrically opposed longitudinally extending slots 9 which project from inner end 8 thereof a substantial distance towards the threaded end thereof.

To permit insertion and removal of the fitting from the housing, a pair of opposed recesses 11 extend into the fitting 7 from its outer end. Such recesses are provided to to accommodate therein a spanner wrench in known fashion. By providing a spanner type screw arrangement as shown, no portion of the fitting projects beyond the housing which could interfere with mounting of the housing in the operative position desired.

The fitting 7 is generally hollow and includes an elongated chamber 12 designed to accommodate therein a portion of the firing mechanism of the device as will be described. Communicating with chamber 12 and extending through the enlarged threaded end of the fitting 7 is a reduced diameter guide way 13 through which another portion of the firing mechanism extends so as to be accessible from the exterior of the housing 2.

The preferred embodiment of the firing mechanism illustrated comprises an elongated cylindrical shank 14 which terminates at its inner end in a generally circular enlarged firing pin supporting portion defined by skirt 16. Positioned coaxially with shank 14 and located generally centrally of the skirt is a firing pin 17 positioned to detonate a donor charge to be selectively aligned therewith as will be described. Skirt 16 is contoured and dimensioned so as to have a smooth sliding fit with the wall defining chamber 12 of the fitting 7. The shank and skirt are normally urged longitudinally of chamber 12 away from the threaded end of the fitting by means of a coil spring 18 which surrounds shank 14 and is interposed between the skirt and seat 15 defined by the upper limit of chamber 12. The shank 14 is slidably received within the aforementioned guide way 13 as noted in FIGS. 1 and 2.

As best seen in FIG. 2, guide way 13 opens into an enlarged recess 18 which normally receives therein the enlarged

flange portions

19 and 21 of a scar 22 which serves as the trigger means of the device. The sear has an aperture 23 therethrough to accommodate a lanyard by means of which the sear may be grasped and withdrawn relative to the housing 2 to actuate the device.

The

flange portions

19 and 21 of the sear define an intermediate annular groove 24 therebetween. Such groove provides a seat for safety means preferably included in the device which precludes inadvertent actuation of the firing mechanism. Such safety means in the embodiment illustrated comprises a shear pin 26 which is positioned within a lateral bore 27 extending from the threaded outer periphery of the enlarged portion of the fitting 7 through and into the enlarged recess 18 therein. When the device is assembled, shear pin 26 is engaged in groove 24 prior to the fitting being threadedly positioned in the housing. It should be understood that upon forcible movement of the sear, the shear pin will be severed to permit the sear to be moved outwardly of the housing.

Preferably a sealing O-ring 28 of rubber or the like, is positioned within another annular groove 29 formed in the sear. The O-ring is normally positioned to engage the wall of recess 18 as best seen in FIG. 1 prior to actuation of the device and precludes entry of foreign matter into chamber 12 of the fitting.

The sear is integrally connected with shank 14 by means of a shoulder portion 31 on the shaft interfitted with a shoulder portion 32 on the inner end of the sear. When spring 18 holds skirt l6 and shank 14 in the position shown in FIG. 1, interengagement of the sear and shank shoulder positions precludes separation thereof because of their orientation within the restricted confines of guide way 13. However, upon the compressing of spring 18 when the sear is pulled outwardly, separation of the sear from the shank is effected as soon as the

shoulder portions

31 and 32 are oriented within the enlarged recess 18 at the outer end of fitting 7. It is such movement of the sear and the shank therewith which arms the device and also results in firing the same in a substantially continuous one step operation incorporating two separate functions as will be described.

Actuation of the device produces detonation in rapid sequence of the donor charge, generally designated 36, and the acceptor charge, generally designated 37. The donor charge is movably mounted in housing 2 and is normally positioned out of alignment with the firing mechanism and, more specifically, with the firing pin 17 thereof. In that regard, as noted from FIGS. 1 and 2, the donor charge is pivotally mounted so that the same may be reoriented from the safe, out-of-line position of FIG. 1 into the armed, in-line position of FIG. 2. When in the latter position, the donor charge is axially aligned with both the firing pin 17 and the acceptor charge 37.

The donor charge, in the form of an explosive train defined by a mass of any suitable known explosive 38, such as RDX or PETN by way of example, is received within a cylindrical metal casing 39. A pair of pivot pins 41 project in opposite directions from the casing and form an axis about which the casing is rotatable. At one end the explosive donor charge includes a standard percussion type primer cap 42 within the casing which is engageable by the firing pin 17 when the donor charge is oriented for firing. Contact of the primer cap by the firing pin detonates the explosive train 38 in known fashion. At its opposite end, the casing is enclosed by a suitable metal cap 43 which maintains the explosive charge within the casing and precludes contamination thereof prior to use.

The casing 39 is pivotally mounted in the hollow interior of fitting 7 between the slotted portions 9 thereof, as best seen in FIG. 3. In that connection, two mating hollow screw members, designated 44 and 46 respectively, form an axle for the pivot pins 41 which project in opposite directions from the casing. The

screws

44 and 46 extend transversely of the fitting and receive the pivot pins 41 therein.

Extending transversely of the fitting in parallel relationship to the axis of casing 39 is stop means in the form of a rigid pin 47 received through opposed

apertures

48 and 49 in the cylindrical wall of the fittign as seen in FIG. 3. The stop pin 47 further serves as an anchor for one end of a coil spring 50 positioned therearound as seen in FIGS. 1 and 3. The coil spring in turn is wound around the axle screws 44 and 46 and its opposite end is hooked over casing 39. Thus, the spring 50 normally urges the casing in a counterclockwise direction as viewed in FIGS. 1 and 2.

It will be noted from FIG. 1 that the tendency of the casing to be rotated counterclockwise is resisted and positively precluded under normal safe conditions of the device by engagement of the skirt 16 of the firing mechanism with the easing. That is, spring 18 which urges the skirt into engagement with the casing holds the casing and its contained donor charge extending generally transversely of the axis of the firing mechanism so that the primer cap 42 and the firing pin 17 are positively maintained out of alignment with and therefore out of accidental contact with each other.

However, upon withdrawal of sear 22 outwardly of the enlarged end 7 of the fitting, coil spring 18 is compressed and skirt 16 is moved upwardly out of contact with casing 39 of the donor charge so that the casing may be pivoted counterclockwise under the effects of spring 50 into contact with stop pin 47 into the in-line armed position shown in FIG. 2. Continued movement of the sear outwardly of the housing results in the sear becoming separated from the remainder of the firing mechanism so that coil spring 18 may urge the skirt and its integral firing pin rapidly inwardly to drive the firing pin into firing contact with the primer cap 42 which in turn detonates the explosive train of the donor charge. Thus, arming and firing of the device, while two separate sequential operations, are effected substantially instantaneously in response to separation of the sear from the remainder of the firing mechanism.

The acceptor charge 37 may take various forms and in the embodiment illustrated is defined by a length of secondary explosive detonating cord, such as a shielded mild detonating cord assembly (SMDC) manufactured and distributed by Explosive Technology, Inc. of Fairfield, California. Such an assembly comprises a metal tube 51, such as stainless steel, within which a length of detonating cord explosive, such as RDX, PETN, I-INS or DIPAM, is positioned. Such an explosive cord effects a point-to-point energy transfer while retaining all detonation by products within the tube 51.

A fitting nut 52 is rotatable relative to tube 51 and includes integral therewith a threaded extension 53 from which projects a sealing ferrule portion 54 terminating in a booster cup 56. The threaded portion of the fitting is received in a threaded bore 57 which communicates with the aforementioned elongated enlarged bore 3 of the housing 2. Bore 57 is stepped as noted to accommodate the acceptor charge assembly therein. Preferably an O-ring seal 58 is positioned on a tapered portion of the fitting to preclude entry of foreign matter into the interior of the housing.

The stepped bore 57 is axially aligned with the axis of shank l4 and the firing pin 17 carried thereby as well as with the longitudinal axis of the donor charge when the latter is pivoted to its armed position. Upon detonation of the donor charge, the detonating cord of the acceptor charge will be detonated in known fashion.

The subject device is designed so that it can be recharged for reuse after inspection has determined no damage has occurred to the housing 2 or fitting 7. To recharge it is merely necessary to remove the carrier fitting 7 from the housing, carrying the donor charge therewith. Upon removing the axle screws 44 and 46, casing 39 may be removed and recharged or replaced with a new casing. Reinsertion of a charged casing into the fitting then prepares the device for reuse, after the acceptor charge cord assembly has similarly been replaced with a fresh charge. The device can be recocked by holding the coil spring 18 compressed while the sear 22 and shank 14 are reengaged, after which the carrier fitting may be reinserted into the housing.

From the foregoing, it should be understood that this invention includes a safe-armed explosive initiation and transfer device in which a donor charge is normally positioned out of alignment with a firing mechanism in such fashion that the same may be automatically moved into alignment with the firing mechanism when it is desired to actuate the device.

Having thus made a full disclosure of this invention, reference is directed to the appended claims for the scope of protection to be afforded thereto.

lclaim:

l. A rapid acting safe-armed explosive transfer device for initiating a controlled detonation in response to actuation of the firing mechanism thereof, comprising a housing having a bore extending thereinto from one end thereof; an acceptor charge positioned at the other end of said housing in operative communication with said bore; a carrier fitting removably received in said bore; firing mechanism within said fitting including trigger means, a firing pin supported by a portion of said firing mechanism positioned to move relative to said fitting, and a spring interposed between said fitting and said firing pin supporting portion; a donor charge pivotally mounted on said fitting; and spring means for urging said donor charge from a first unarmed position in which the same is out of alignment with said firing pin toward a second armed position in which the same is in alignment with said firing pin; said firing pin supporting portion normally engaging said donor charge and maintaining the same in said first out-of-line position until said trigger means is actuated at which time said spring means positively urges said donor charge to said second in-line position, said donor charge being automatically moved to said secondposition substantially simultaneously with actuation of said trigger means; said fitting being removable from said housing following controlled detonation of said donor charge and acceptor charge to permit rearming of said device.

2. The device of claim 1 in which said donor charge is pivotally mounted within said fitting and normally is held by said firing pin supporting portion to extend transversely of said firing mechanism out of detonatable contact therewith, said donor charge being pivotal to extend generally longitudinal of said fitting when moved to said second position by said spring means.

3. The device of claim 1 in which said donor charge comprises a casing, an explosive train within said casing, and pivot pins projecting in opposite directions from said casing, and in which said spring means for moving said donor charge into alignment with said firing mechanism comprises a spring engaged with said casing, said casing being pivotally mounted in said fitting by means of said pivot pins.

4. The device of claim 1 in which said donor charge comprises an explosive train pivotally mounted in said fitting, and in which said acceptor charge comprises a length of detonating cord one end of which is mounted in said housing in line with said donor charge when said donor charge is moved into said armed position in which it is aligned with said firing mechanism.

5. A rapid acting safe-armed explosive transfer device for initiating a controlled detonation at a location spaced from said device in response to actuation of the firing mechanism thereof, comprising a housing having a bore extending thereinto from one end thereof; an acceptor charge positioned at the other end of said housing in operative communication with said bore; said acceptor charge including structure for effecting transfer of explosive energy from said device to said spaced location in controlled fashion; a carrier fitting removably received in said bore; firing mechanism within said fitting and including a sear at one end thereof accessible for outside said housing, a firing pin and a surrounding skirt at the other end thereof positioned to move relative to said fitting, and a spring interposed between said fitting and said skirt; a donor charge pivotally mounted on said fitting adjacent an inner end thereof, and a spring for urging said donor charge from a first unarmed position in which the same is out of alignment with said firing pin toward a second armed position in which the same is in alignment with said firing pin; said skirt normally en aging said donor charge and maintaining the same in sal first out-of-line post 10!] until said sear lS withdrawn relative to said fitting at which time such spring positively urges said donor charge to said second in-line position, said donor charge being automatically moved to said second position substantially simultaneously with withdrawal of said sear; said fitting being removable from said housing following controlled detonation of said donor charge and acceptor charge to permit rearming of said device.

6. The device of claim 5 in which said sear is separable from said skirt when withdrawn at predetermined distance from said fitting so that said skirt and said firing pin thereafter are urged toward said donor charge under the effects of said first mentioned spring to detonate said donor charge.

7. The device of claim 5 which includes stop means with which said donor charge is engageable when said sear is withdrawn and said charge is pivoted to said second position, said stop means maintaining said charge properly aligned with said firing pin.

8. The device of claim 5 in which said donor charge comprises an explosive train positioned in a casing which is pivotally mounted on said fitting, and in which said acceptor charge comprises a length of detonating cord.

9. The device of claim 5 which includes severable safety means extending through said fitting into engagement with said sear to preclude inadvertent withdrawal of said sear from said fitting.

Claims

1. A rapid acting safe-armed explosive transfer device for initiating a controlled detonation in response to actuation of the firing mechanism thereof, comprising a housing having a bore extending thereinto from one end thereof; an acceptor charge positioned at the other end of said housing in operative communication with said bore; a carrier fitting removably received in said bore; firing mechanism within said fitting including trigger means, a firing pin supported by a portion of said firing mechanism positioned to move relative to said fitting, and a spring interposed between said fitting and said firing pin supporting portion; a donor charge pivotally mounted on said fitting; and spring means for urging said donor charge from a first unarmed position in which the same is out of alignment with said firing pin toward a second armed position in which the same is in alignment with said firing pin; said firing pin supporting portion normally engaging said donor charge and maintaining the same in said first out-of-line position until said trigger means is actuated at which time said spring means positively urges said donor charge to said second in-line position, said donor charge being automatically moved to said secondposition substantially simultaneously with actuation of said trigger means; said fitting being removable from said housing following controlled detonation of said donor charge and acceptor charge to permit rearming of said device.

5. A rapid acting safe-armed explosive transfer device for initiating a controlled detonation at a location spaced from said device in response to actuation of the firing mechanism thereof, comprising a housing having a bore extending thereinto from one end thereof; an acceptor charge positioned at the other end of said housing in operative communication with said bore; said acceptor charge including structure for effecting transfer of explosive energy from said device to said spaced location in controlled fashion; a carrier fitting removably received in said bore; firing mechanism within said fitting and including a sear at one end thereof accessible for outside said housing, a firing pin and a surrounding skirt at the other end thereof positioned to move relative to said fitting, and a spring interposed between said fitting and said skirt; a donor charge pivotally mounted on said fitting adjacent an inner end thereof, and a spring for urging said donor charge from a first unarmed position in which the same is out of alignment with said firing pin toward a second armed position in which the same is in alignment with said firing pin; said skirt normally engaging said donor charge and maintaining the same in said first out-of-line position until said sear is withdrawn relative to said fitting at which time such spring positively urges said donor charge to said second in-line position, said donor charge being automatically moved to said second position substantially simultaneously with withdrawal of said sear; said fitting being removable from said housing following controlled detonation of said donor charge and acceptor charge to permit rearming of said device.

6. The device of claim 5 in which said sear is separable from said skirt when withdrawn a predetermined distance from said fitting so that said skirt and said firing pin thereafter are urged toward said donor charge under the effects of said first mentioned spring to detonate said donor charge.