US3059576A

US3059576A - Electrically fired detonator

Info

Publication number: US3059576A
Application number: US763700A
Authority: US
Inventors: Arthur E Haefner
Original assignee: Conax Corp
Current assignee: Conax Corp
Priority date: 1958-09-26
Filing date: 1958-09-26
Publication date: 1962-10-23
Anticipated expiration: 1979-10-23

Description

Oct. 23, 1962 A. E. HAEF N ER 3,059,576

ELECTRICALLY FIRED DETONATOR Filed Sept. 26, 1958 INVENTOR.

United States Patent Ofifice atsas rt Patented Get. 23, 1962 3,059,576 ELECTRICALLY FIRED DETONATOR Arthur E. Haefner, Snyder, N .Y., assignor to Conax Corporation, Buffalo, N.Y., a corporation of New York Filed Sept. 26, 1958, Ser. No. 763,700 6 Claims. (Cl. 162-28) This invention relates to improvements in electrically fired detonators.

Electrically fired detonators are used for various purposes, such as in explosive actuated valves in which a ram is driven through a diaphragm separating inlet and outlet chambers of a normally closed valve, or the ram is driven to close off a passage in a normally open valve. Instead of using the ram to open or close a valve, it might be/adapted as a pull-pin in an explosive latch pin device. "An example of an electrically fired detonator used in a single operation normally closed explosive actuated valve is disclosed in United States Patent No. 2,815,882.

Detonators of this general class as heretofore constructed had various disadvantages which are overcome by a detonator constructed in accordance with the principles of the present invention. Some of these disadvantages included difiicultyof manufacture to produce uniform firing characteristics from detonator to detonator of the same size and type, and blow back of gases around the lead in wires requiring special sealing means to prevent such blow back and involving the assembly of various parts when the detonator was mounted on a supporting member.

An important object of the present invention is to provide an improved electrically fired detonator in which when fired the escape of gases around the lead in wires is effectively sealed in a simple and improved manner.

Another object is to provide such a detonator which is compact in size and 'weight, this being an important advantage in certain applications such as on guided missiles and the like where available space is limited and weight is restricted.

Another object is to provide such a detonator which is a fully assembled unitary structure or instrumentality which can be quickly and easily attached to a member with which the detonator is intended to be operatively associated.

A further aim is to provide such a detonator which is easy to manufacture in quantity with the firing characteristics being uniform from one to another of the same lot and which is dependable in performance.

A further object is to provide such a detonator to which it is easy to make an electrical connection to a source of electrical energy.

Other objects and advantages of the present invention will be apparent from the following detailed description and accompanying drawing in which:

FIG. 1 is a longitudinal central sectional view of an improved electrically fired detonator constructed in accordance with the principles of the present invention and showing the same mounted on a supporting member illustrated as a cylinder for a ram.

FIG. 2 is a transverse sectional view thereof, taken on line 22 of FIG. 1.

FIGS. 3 through 9 are longitudinal central sectional views of an intermediate portion of the detonator of FIG. 1 but on a reduced scale as com-pared thereto, and

illustrating various stages through which the detonator goes in its method of manufacture.

FIG. 10 is an end View, similar to FIG. 2, and showing a first modified form of detonator provided with a single lead in wire.

FIG. 11 is a similar view but showing a second modified form having three lead in wires.

FIG. 12 is a similar view but showing a third modified form having four lead in wires. I

FIG. 13 is a fragmentary view of the left end portion of the detonator shown in FIG. 1 but modified to illustrate a socket type structure for electrical connection instead of a prong type structure as illustrated in FIG. 1.

Referring to FIG. 1, the improved detonator comprises a body 20; one or more lead in wires, two being shown at 21 and 22; a ceramic body 23 in which the lead in wires are embedded and housed within the main body 20; one or more bridge wires connecting the ends of the lead in wires, one being shown at 24; a sleeve 25 surrounding the bridge wire; an ignitor body 26 arranged in the sleeve 25; and a cup-shaped shell 27 connected to the main body 20 and containing the main charge 28.

The main body 20 is shown as an elongated tubular metallic member having a centrally located longitudinal cylindrical stepped bore, larger at its inner end as indicated at 29 than at its outer end 30 and connected by an intermediate annular shoulder 31 which faces inwardly or to the right as viewed in FIG. 1. Plugging this stepped bore is the ceramic body 23, preferably glass, through which the lead in

wires

21 and 22 extend longitudinally from end to end in spaced relation to each other. The ceramic plug 23 is fused to the surrounding wall of the detonator body 20 completely filling the stepped bore thereof and thereby having an annular shoulder 32 engaging the shoulder 31 on the body. The ceramic plug 23 is also fused to the lead in

wires

21 and 22 and serves to insulate them from each other and from the detonator body.

The corresponding ends of the main body 20, ceramic body 23 and lead in

wires

21 and 22 lie in a common transverse plane forming a flat face 33 against which the bridge wire 24 is arranged. This bridge wire is very fine as compared to the lead in

wires

21 and 22 and its ends are severally soldered to the exposed end faces of these lead in wires.

The sleeve 25 is a cylindrical tubular member, preferably made of fibre board, which embraces a neck portion 34 of reduced diameter formed on the inner end of the main body 20. Adjacent the neck 34 but axially spaced therefrom and remote from the bridge wire 25, the main body 20 is provided with an annular external groove 35 which receives the turned in annular flange 36 formed on the rim portion of the cup shaped shell 27.

The main body 20 is shown as having an external thread 38 for a portion of its length and arranged intermediate the crimping groove 35 and an enlarged portion 37. The root diameter of the thread 38 is slightly larger than the external diameter of the shell 27. The periphery of the enlarged portion 37 is suitably formed to permit the application of a tool (not shown) for turning the main body 20 about its longitudinal axis. Conveniently such periphery may be hexagonal in shape in order to permit the application of an ordinary wrench. v

In FIG. 1, the outer ends of the lead in

wires

21 and 22 are shown as connected to

prongs

39 and 40, respectively, which form enlarged axial extensions of the lead in wires partially embedded in the ceramic body 23. The main body 20 is shown as formed with an integral tubular, externally threaded, extension 41 which surrounds the exposed portions of the

prongs

39 and 40 and in spaced relation thereto. This extension 41 is adapted to receive a receptacle (not shown) having sockets into which the a different type of electrical connection. As there shown, the outer ends of the lead in

wires

21 and 22 may be formed as

socket members

42 and 43, respectively, arranged in an enlarged recess 44 in the tail or outer end of the detonator body and adapted to receive the prongs of an electrical plug (not shown).

Referring again to FIG. 1, the detonator is shown as mounted on a cylinder 45 having a chamber 46 receiving the shell 27 of the detonator, a bore 48 of slightly reduced diameter in which a ram 49 is movably arranged and adapted to be driven to the right or away from the detonator when the latter is fired. In order to fasten the detonator to the cylinder 45, the outer portion of the chamber 46 of the latter is internally threaded as indicated at '50 to receive the external thread 38 on the detonator body. It will be noted that the detonator is screwed into the ram cylinder 45 until the inner face of the enlarged portion 37 of the detonator body 20 abuts the outer end face of this cylinder, thereby giving good sealing to the outer end of the chamber 46.

With the lead in

wires

21 and 22 of the detonator connected to a source of electrical energy, as previously described, when a sufficient current is passed through the bridge wire 24, depending upon its resistance, this wire glows and ignites the ignitor charge 26 which in turn sets off the main charge 28. The resulting detonation ruptures and blows out the end Wall of the shell 27 permitting the gases generated to drive the ram 49 or equivalent device forwardly.

Any suitable chemical or mixture of chemicals may be used for the ignitor charge 26 and main charge 28. Excellent results have been obtained with diazodinitrophenol with 1% nitrostarch added as binder, for the ignitor charge 26; and 100% diazodinitrophenol for the main charge 28. The electrical input required to fire a detonator depends upon the bridge wire resistance and the composition of the ignitor charge. The power obtained from a detonator is deter-mined by the size and composition of the base charge 28 which may be varied to meet particular needs.

The design of detonator described lends itself to an easy method of manufacture which assures uniformity in the firing characteristics of similar detonators and provides functional reliability. Firing characteristics, aside from the variables previously mentioned, depend upon the compaction or compression of the ignitor and base charges during assembly of the detonator; and dependability involves protection of the fragile one or more bridge wires.

The method of assembling the two lead in wire detonators shown in FIG. 1 is outlined in FIGS. 3 through 9. A preformed ceramic plug arranged in the stepped bore of the detonator body 20 and having spaced holes through which the lead in

wires

21 and 22 extend, is heated to fuse the ceramic body 23 to the detonator body and also to the lead in wires, as depicted in FIG. 3. The end of this sub-assembly is then rendered smooth as by grinding to provide the flat transverse end face 33 shown in FIG. 4. The bridge wire 24 is then placed against the fiat face 33 and soldered at its ends to the exposed ends of the lead in

wires

21 and 22. Following this the sleeve 25 is slipped on the neck 34, as shown in FIG. 6. The outwardly projecting part of the sleeve 25 and the flat face 33 jointly form a recess into which the ignitor charge 26 is buttered, as shown in FIG. 7. The shell 27 which is preferably of copper and containing a predetermined amount of powder forming the main charge 28 is then slipped over the sleeve with the rim of the shell overlapping the crimping groove 35, as shown in FIG. 8. With the ignitor and main charges compressed to a predetermined degree by pressing the shell 27 axially toward the detonator body 20, the rim portion of the shell is rolled over or crirnped in the groove 35, as shown in FIG. 9, thus completing the assembly. Crimping may be effected by any suitable tool.

It is to be noted that the bridge wire 24, or additional ones if used, are arranged against the supporting fiat face 33, facilitating soldering and also minimizing breaking or dislodgement of the wire or wires when the ignitor charge is subsequently applied or even when the ignitor and main charges are compressed against the wire or wires.

It will also be observed that the ceramic body 23 because of its inner end portion being larger than its outer end portion is prevented from being blown out of the detonator body when the detonator is fired. Also, because fused both to the detonator body and lead in wires, effective sealing is provided.

As previously explained, one or more lead in wires may be employed. Instead of the two lead in wires arrangement shown in FIGS. 1 and 2, there may be one, three or four lead in wires used as shown in FIGS. 10, 11 and 12, respectively. Multiple lead in wires may be desired to insure the detonator being fired.

In FIG. 10, the single lead in wire 55 is connected by a bridge wire 56 to the detonator :body 20. In this arrangement, the bridge wire is grounded to the detonator body.

In FIG. 11, three lead in

wires

57, 58 and 59 are shown as connected in a delta arrangement by three

bridge wires

60, 61 and 62. Current passed through any pair of lead in wires and the associated bridge wire will fire the detonator.

In FIG. 12, four lead in

wires

63, 64, 65, and 66 are shown as connected in a square arrangement by four

bridge wires

67, 68, 69 and 70. Current through any pair of lead in wires and the intermediate bridge wire will fire the detonator.

In all the cases of FIGS. 2, 10, 1'1 and 12, the lead in wires are embedded in a ceramic body, in turn fused to the detonator body. This effectively prevents rearward escape of gases.

From the foregoing it will be seen that the construction of the detonator described achieves the various stated objects of the invention.

I claim:

1. In an electrically fired detonator, the combination comprising a mountable tubular main body, a ceramic body arranged completely within said main body and having an end face, at least one lead in wire extending through said ceramic body to said end face, said ceramic body being fused to said main body and also to said lead in wire, at least one bridge Wire arranged against said end face and electrically connected to said lead in wire, a shell embracing a portion of said main body and secured thereto, a main charge contained within said shell, and an ignitor charge arranged between said main charge and said bridge wire and in contact with both.

2. In an electrically fired detonator, the combination comprising a mountable tubular main body, a ceramic body arranged within said main body and having an end face, means arranged to prevent axial displacement of said ceramic body relative to said main body in at least one direction, at least one lead in wire extending through said ceramic body to said end face, said ceramic body being fused to said main body and also to said lead in wire, at least one bridge wire arranged against said end face and electrically connected to said lead in wire, a shell embracing a portion of said main body and secured thereto, a main charge contained within said shell, and an ignitor charge arranged between said main charge and said bridge wire and in contact with both.

3. In an electrically fired detonator, the combination comprising a mountable tubular main body having a stepped bore larger at one end, a ceramic body plugging said bore and conforming to the shape thereof and having an end face flush with an end of said main body, at least one lead in Wire extending through said ceramic body to said end face, said ceramic body being fused to said main body and also to said lead in wire, at least one bridge wire arranged against said end face and electrically connected to said lea-d in wire, a shell embracing a portion of said main body and secured thereto, a main charge contained Within said shell, and an ignitor charge arranged between said main charge and said bridge wire and in contact with both.

4. In an electrically fired detonator, the combination comprising a tubular main body, a ceramic body plugging said body and having an end face flush with an end of said main body, at least one lead in wire extending through said ceramic body to said end face, said ceramic body being fused to said main body and also to said lead in Wire, at least one bridge wire arranged against said end face and electrically connected to said lead in wire, a reduced neck on the end of said main body, a sleeve member partially arranged on said neck, an ignitor charge surrounded by said sleeve member and contacting said bridge wire, a shell surrounding said sleeve member and secured to said main body, and a main charge contained within said shell and contacting said ignitor charge.

5. In an electrically fired detonator, the combination comprising a tubular main body, a ceramic body plugging said body and having an end face flush with an end of said main body, at least one lead in wire extending through said ceramic body to said end face, said ceramic body being fused to said main body and also to said lead in wire, at least one bridge Wire arranged against said end face and electrically connected to said lead in wire, a reduced neck on the inner end of said main body, a sleeve member partially arranged on said neck, an ignitor charge surrounded by said sleeve member and contacting said bridge wire, an annular groove arranged in the exterior of said main body adjacent said sleeve member, a cup-shaped shell surrounding said sleeve member and having an inturned rim portion received in said groove, and a main charge contained within said shell and contacting said ignitor charge.

6. An electrically fired detonator, comprising a tubular main body having an externally threaded portion and another external portion adapted to receive a tool for turning the same, a ceramic body arranged within said main body and having an end face, at least one lead in wire extending through said ceramic body to said end face, said ceramic body being fused to said main body and also to said lead in wire, means adapted to make an electrical connection with said lead in wire, at least one bridge wire arranged against said end face and electrically connected to the said lead in wire, a cup-shaped cylindrical shell embracing a portion of said main body and secured thereto, the outside diameter of said shell being no greater than the root diameter of said externally threaded portion, a main charge contained Within said shell, and an ignitor charge arranged between said main charge and said bridge wire and in contact with both.

References Cited in the file of this patent UNITED STATES PATENTS 164,921 Kalmback June 29, 1875 1,975,608 Kirst Oct. 2, 1934 2,386,211 Grant Oct. 9, 1945 2,393,629 Grant June 29, 1946 2,687,667 Gunther Aug. 31, 1954 2,801,585 Smith Aug. 6, 1957 2,842,059 Plumley July 8, 1958 2,880,671 Lutz et al. Apr. 7, 1959 2,881,703 Volpert Apr. 14, 1959 2,915,012 Hengel Dec. 1, 1959 FOREIGN PATENTS 982,837 France June 15, 1951