Safety And Arming Device

Abstract

A safety and arming device having a mild detonating explosive fuze train of insensitive heat resistant explosives for centrally detonating a very large explosive charge and being separated in a safe, unarmed position from an initiating detonator by an electrically actuated normally out-of-line interrupter.

Description

BACKGROUND OF THE INVENTION

This invention generally relates to arming devices and more particularly to a mild detonating explosive fuze train for detonating a very large explosive charge at the center thereof.

There are many important requirements for arming devices being used for setting off very large explosive charges in military ordinance applications. They include high reliability and, most importantly, for insuring maximum efficiency in detonation of the charge, means for detonating the charge at its center. Heretofore, sheet explosives have been used with a safety and arming device and a very large detonator to accomplish this desired end. Such explosives have included, for example, PETN suspended in a rubber or plasticlike matrix having a thickness and flexibility proximate to that of an innertube of an automobile tire. It has been strung through the large explosive charge. This method has been found to be inadequate, however, because it has been unreliable, unsafe in many instances and because the large explosive charge is not detonated at its center when it is used.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a reliable safety and arming device for efficiently detonating a large explosive charge.

Another object of the present invention is to provide an arming device for detonating a large explosive charge at the center thereof.

A further object of the invention is the provision of a mild detonating explosive train for detonating a large explosive charge at its center.

Yet another object of the invention is the provision of an electrically actuated safe and reliable mild detonating explosive train for centrally detonating a large explosive charge.

Briefly, in accordance with one embodiment of the invention, the foregoing and other objects are attained by a safety and arming device having an insensitive detonator, an electrically actuated rotor for moving an insensitive heat resistant explosive from a safe, out-of-line position to an armed position wherein it is aligned with the detonator and a mild detonating cord leading to a booster positioned within the large explosive charge, and an insensitive heat resistant explosive booster at each end of the detonating cord. Among the heat resistant explosives which have been used and proven dependable in devices constructed in accordance with the teachings of this invention are those in the polynitro-aromatic group of explosives.

BRIEF DESCRIPTION OF THE DRAWING

A more complete appreciation of the invention and many of its attendant advantages will be readily apparent as the same becomes better understood by reference to the detailed description when considered in connection with the accompanying drawing wherein:

FIG. 1 is a sectional view of a preferred embodiment of the present invention showing the interrupter-rotor in its out-of-line safe, or unarmed, position; and

FIG. 2 is a sectional view of the interrupter-rotor portion only of the device illustrated in FIG. 1, rotated 90.degree. to the aligned, or armed, position thereof.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to the drawing, reference numeral 10 designates generally a substantially cylindrical support having an axial bore 11 therethrough in which is positioned a cylindrical rotor 12 adapted to be rotated therein about its longitudinal axis by an electric motor 13 mounted on one end of support 10. Positioned in the sidewall of the support 10 along a line parallel to the longitudinal axis of the support are a pair of parallel radial bores 14, 14' opening into the axial bore 11. Diametrically opposed to the radial bores 14, 14' in the support 10 there is provided a second pair of parallel radial bores 15, 15' opening into the axial bore 11 and aligned respectively with radial bores 14, 14'.

The rotor 12 is provided with a pair of through bores 16, 16' transverse to the longitudinal axis thereof and lying in a plane containing said axis. These transverse bores 16, 16' are positioned at right angles to the radial bores 14, 14' and 15, 15' in the wall of support 10 in one position of the rotor 12, as illustrated in FIG. 1, and are aligned with the radial bores 14, 14' and 15, 15', respectively, when rotor 12 is rotated to a second predetermined position 90.degree. from that of the first position by the electric motor 13, as illustrated in FIG. 2. Positioned within the rotor 12 transverse to the longitudinal axis thereof and parallel to the other transverse bores 16, 16' therein is a third through bore 17, the purpose of which will become more apparent as the description proceeds.

A pair of detonator assemblies generally indicated by numerals 18, 18', and each comprising a sleeve 19 having an electroresponsive detonator 20 secured therein in any well-known manner, are secured in threaded engagement with the support 10 in the radial bores 14, 14', respectively, thereof. Each detonator is provided with a pair of terminals 21 for establishing an external electrical connection thereto whereupon the detonator may be fired in response to an electrical impulse received thereby.

Arranged within the transverse bores 16, 16' of the rotor 12 are a pair of lead-in charges 22, comprised of any suitable insensitive heat resistant explosive material such as, for example, hexanitrostilbene, hereinafter referred to as HNS. The term "heat resistant explosive" as used herein includes those explosives which have a melting point in excess of 300.degree. C., a vacuum thermal stability such that they decompose at a rate less than 2.0 cc./g./hr. at 260.degree. C., a particle size ranging from 10 to 725 microns, and which exhibit substantially no weight loss when subjected to temperatures of 210.degree. C. for a period of 48 hours.

The preparation of HNS has been described in the application of Kathryn G. Shipp, Ser. No. 365,572, filed May 5, 1964 and involves a one-step reaction which comprises the addition of a solution of 2,4,6-trinitrotoluene to an aqueous solution of an alkaline metal hypochlorite and then recovering the resulting product.

When the arming rotor 12 is moved to the armed position of FIG. 2 the HNS-leads 22 are brought into alignment with the detonators 20 and with a pair of HNS-end boosters 23 positioned within radial bores 15, 15' of support 10 and secured therein in any well known manner.

A metallic tubing 24 may be used to provide a path from the end boosters 23 in the support 10 to a second pair of end boosters 25, which may also be comprised of HNS-explosive, securably fastened within a support 26 for a sub-booster charge 27 positioned centrally in a large explosive, which it is desired to detonate in a safe, reliable and efficient manner. The tubing 24 is filled with an insensitive heat resistant explosive, preferably dipicramid, hereinafter referred to as DIPAM, thereby forming a mild detonating cord or fuze between the HNS-end boosters 23 and 25.

DIPAM may be prepared according to any of a number of known methods such as, for example, the methods disclosed by Mortimer J. Kamlet et al in U.S. Pat. No. 3,320,320 and by Robert E. Oesterling et al in U.S. Pat. No. 3,404,184.

The operation of the device will be readily apparent from the foregoing description. An arming wire 29 inserted in transverse bore 17 of rotor 12 and through a cooperating aperture or bore in the support 10 for preventing any relative movement therebetween and so maintaining the rotor in a safe position during handling is removed therefrom before the device is to be armed. By actuating the electric motor 13, the rotor 12 is rotated from its safe position shown in FIG. 1 to its armed position shown in FIG. 2, wherein the detonators 20, HNS-leads 22 and HNS-end boosters 23 are properly aligned. Initiation of the detonators 20 by an electrical impulse received thereby creates a detonation front which travels via the path defined by HNS-leads 22, HNS-end boosters 23, the DIPAM mild detonating cord 24, and HNS-end boosters 25 to the sub-booster 27. The explosive force along this path is of such a low magnitude that the metallic tubing 24 is not ruptured, thus enabling an explosion to be safely conducted along a path from an interrupter to a large explosive charge.

Briefly stated in summary, according to the present invention, a safety and arming device is provided for use in detonating a very large explosive charge at its center in which an explosive fuze train having insensitive heat resistant-explosive end boosters and an intermediate mild detonating cord is provided beyond the interrupter.

Obviously many modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

Claims

What is claimed as new and desired to be secured by Letters Patent of the United States is:

1. A device for detonating a large explosive charge comprising:

a sub-booster charge displaceable within said large explosive charge,

an explosive train including first and second end boosters of heat resistant explosive material explosively coupled together by a metallic tube filled with mild detonating explosive material, said second end booster being positioned to detonate said sub-booster,

detonator means for actuating said first end booster,

arming means coupled between said detonator means and said first end booster and operative in an initial safe position to interrupt the explosive path therebetween and in a subsequent arming position to explosively connect said detonator means to said first end booster, and

drive means for moving said arming means from said initial safe position to said arming position.

2. A device according to claim 1 wherein said arming means includes a cylindrical support having an axial bore therethrough,

a rotor positioned within said axial bore and connected to said drive means for rotation thereby,

said support having diametrically opposed radial bores therein communicating with said axial bore for housing said detonator means and said first end booster,

said rotor having a through bore transverse to said axial bore,

an explosive lead in said transverse bore,

and said transverse bore being out-of-line with said radial bores in said initial position of said rotor and aligned therewith when said rotor is in said armed position.

3. A device according to claim 1 wherein said heat resistant explosive material in said end boosters is hexanitrostilbene.

4. A device according to claim 1 wherein said mild detonating explosive material in said metallic tube is dipicramid.

5. A device according to claim 2 wherein said drive means for moving said rotor is an electric motor fixedly secured to said cylindrical support.

6. A device according to claim 5 wherein said detonator means is an electroresponsive detonator.

7. A device according to claim 2 wherein said heat resistant explosive material in said end boosters is hexanitrostilbene,

said mild detonating explosive material is dipicramid, and

said explosive lead in said transverse bore is hexanitrostilbene.

8. A device according to claim 7 wherein said rotor is provided with a removable safety arming wire to prevent relative movement between said rotor and said cylindrical support during handling and storage thereof.