US3793954A

US3793954A - Dynamite detonator assembly

Info

Publication number: US3793954A
Application number: US00237851A
Authority: US
Inventors: M Johnston
Original assignee: Individual
Current assignee: Individual
Priority date: 1972-03-24
Filing date: 1972-03-24
Publication date: 1974-02-26
Anticipated expiration: 1991-02-26

Abstract

A detonator assembly for sticks of dynamite which includes a cup-like housing having a pointed tubular prong therein which contains a detonator, whereby when the housing is forced onto the end of the dynamite, the prong with the detonator therein becomes embedded in the dynamite. In one embodiment, the detonator is activated by a powder fuse which extends from the housing, and in another embodiment it is activated electrically through conductors which extend from the housing. The electrical embodiment also includes by-pass filter means for preventing the detonator from being prematurely activated by extraneous alternating electro-magnetic impulses.

Description

United States Patent [191 Johnston Feb. 26, 1974 DYNAMITE DETONATOR ASSEMBLY Primary Examiner-Verlin R, Pendegrass [76] Inventor: Mack S. Johnston, 26 Hitching Post [22] Filed: 1972 A detonator assembly for sticks of dynamite which in- [21] Appl. No.; 237,851 cludes a cup-like housing having a pointed tubular prong therein which contains a detonator, whereby when the housing is forced onto the end of the dyna- [52] U.S. Cl. 102/28 R, 102/24 R mite the prong with the detonator therein becomes [51] Int. Cl. F42b 3/10, F42b 3/18 embedded in the dynamite In one embodiment the Fle'd 0f Search 28, detonator is activated y a powder fuse which extends from the housing, and in another embodiment it is ac- [56] References cued tivated electrically through conductors which extend UNITED STATES PATENTS from the housing. The electrical embodiment also inl,512,714 10/1924 Saucier 102/24 cludes by-pass filter means for preventing the detona- 2,754,756 7/.1956 Duesing 102/24 tor from being prematurely activated by extraneous 2,755,735 7/1956 l-larter, .lr. 102/24 alternating electro-magnefic impulses, 3,018,733 l/l962 Johnson lO2/70.2

12 Claims, 6 Drawing Figures DYNAMITE DETONATOR ASSEMBLY BACKGROUND OF THE INVENTION The present invention relates generally to the explosives art, and more particularly to a novel dynamite detonator assembly for use with either electrical or black powder ignitors.

As is well known in the art, explosive charges such as sticks of dynamite are widely used in mining operations and surface construction projects such as road building and the like, where it is necessary to fracture and/or dislodge large masses of rock and/or ore-bearing strata.

Furthermore, it is well known that such explosive charges are usually set off" or activated by a highly sensitive detonator such as a small tubular container of fulminate of mercury, which, in turn, is activated by an electrical current or by burning black powder.

One of the problems when using sticks of dynamite as the explosive charge, is that it is necessary to physically embed the detonator in one end of a stick of dynamite, as by gouging out a hole with a small pointed tool. This procedure has many disadvantages; it is timeconsuming, the breaking of the paper covering over the end of the dynamite permits moisture to enter the dynamite, and special precautions must be taken to securely anchor the detonator in the dynamite.

Although the use of an electrical current to actuate the detonator has many advantages over a black powder fuse, the primary disadvantage of using the electrical means is that the detonator is very sensitive and very minute, extraneous high-frequency electromagnetic impulses such as those eminating from the radio equipment of a low-flying aircraft or from the ignition system of an automobile, can activate the detonator and cause a premature explosion with attendant disastrous consequences.

SUMMARY OF THE INVENTION With the aforementioned limitations and deficiencies of prior detonator arrangements in mind, it is a primary object of the present invention to provide a novel dynamite detonator assembly which houses a detonator and which can be easily and quickly applied to one end of a stick of dynamite, such that the detonator is embedded in the end of the dynamite in a relatively moistureproof manner. More particularly, it is an object to provide such an assembly which includes a sleeve-like housing which is adapted to slip over the end of the dynamite in sealing relationship therewith and which includes a prong-like housing for the detonator, whereby the act of forcing the sleeve over the end of the dynamite causes the detonator to be embedded in the end of the dynamite.

Another object is to provide an electrically activated dynamite detonator assembly which cannot be inadvertently activated by extraneous electrical impulses from aircraft and/or nearby automotive equipment. More particularly, it is an object to provide such an electrical detonator assembly which includes a by-pass circuit for preventing such extraneous alternating impusles from reaching the detonator.

A further object is to provide such a detonator assembly which can be easily and quickly fastened to a stick of dynamite by inexperienced personnel, after very little instruction.

Yet another object is to provide a novel dynamite detonator assembly which is simple in construction and relatively inexpensive to manufacture.

An additional object is to provide such a detonator assembly in which the detonator material, such as fulminate of mercury, can be housed in a cavity contained in said assembly, without requiring a separate shell or container therefor.

I have discovered that the foregoing objects and advantages are achieved by a novel detonator assembly which includes a cup-like housing adapted to be forced over the end of a dynamite stick, and which supports a pointed tubular prong therein which is forced through the end of the dynamite and becomes embedded therein, said tubular spring containing the detonator for exploding the dynamite. In one embodiment, the detonator is activated by a powder fuse which extends from the housing, and in another embodiment it is activated by direct current through conductors which extend from the housing. In the second or electrical embodiment, the circuit within the housing is provided with a filter for by-passing extraneous alternating electro-magnetic impulses, and with a low amphere fuse which must be blown before current can reach the detonator.

BRIEF DESCRIPTION OF THE DRAWING In the drawing:

FIG. 1 is a perspective view of a stick of dynamite provided with a detonator assembly embodying the teachings of the present invention, with the sealing cap removed, which assembly is of the type wherein the detonator is activated by burning powder:

FIG. 2 is an enlarged, fragmentary, vertical sectional view of the upper end of the assembly shown in FIG. 1;

FIG. 3 is an perspective view of a stick of dynamite provided with a detonator assembly which is of the type wherein the detonator is activated by an electrical current;

FIG. 4 is an enlarged, fragmentary, vertical sectional view of the upper end of the assembly shown in FIG. 3;

FIG. 5 is an exploded view, in perspective, of the components of the detonator assembly shown in FIG. 4; and

FIG. 6 is an schematic diagram of the electrical circuit for use with the detonator assembly shown in FIGS. 3-5.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawing more particularly by reference numerals, and specifically to FIGS. 1 and 2, the number 10 indicates generally the powder-igniting form of dynamite detonator assembly constructed in accordance with the teachings of the present invention, shown applied to a stick 12 of dynamite of conventional cylindrical construction encased in a paper covering and which includes an end surface 14 and a side peripheral surface 16.

The detonator assembly 10, which is preferably made from a plastic material, comprises a cylindrical housing 18 with an inner side surface 20, and a longitudinally extending hollow ridge 22 which provides a passageway 24 for a length 26 of black powder fuse which is connected to a detonator 28 of conventional construction.

A domed end wall 30 extends over the upper or outer end of the housing 18 to adjacent the ridge 22, and supports a depending tubular prong 32 which is open at its upper end and which receives the detonator 28. The tubular prong 32 is positioned adjacent the inner surface 20 diametrically opposite to the ridge 22 and has a pointed inner end 34 for a purpose to appear, and opposed apertures 36 adjacent said end. The axis of the prong 32 is substantially parallel with the longitudinal axis of the cylindrical housing 18.

The domed end wall 30 also supports an arcuate channel 38 which extends from the upper end of the tubular prong 32, toward the upper open end of the ridge 22 so as to receive and support a portion of the black powder fuse 26.

Extending over the domed end wall 30, the arcuate channel 38 and the upper end of the longitudinal passage 24, is a cap 40 also of plastic material, which is cemented in position to provide a moisture-proof end seal.

To prepare the novel detonator assembly for use and prior to cementing the cap 40 in position a detonator 28 (with a short length of black powder fuse attached thereto) is inserted in the tubular prong 32 so that the lower end of the detonator is adjacent the apertures 36. The free end of the fuse is then inserted downwardly through the passageway 24 in the ridge 22, and the intermediate portion of the powder fuse is pressed into the channel 38. The cap 40 is then cemented in position, thereby sealing the upper or outer end of the assembly.

As an alternative construction, in place of the separate detonator 28, a measured amount of the detonator material such as fulminate of mercury can be deposited in the tubular prong 32 and one end of the fuse 26 inserted into it. This further decreases the cost of the assembly, and makes it more economically desirable.

In use, the pointed inner end 34 of the tubular prong 32 is positioned against the end surface 14 of the dynamite, close to the side peripheral surface 16, and the housing 18 is then forced downwardly over the end of the dynamite so that the tubular prong 32 penetrates into and becomes embedded in the interior of the dynamite, with the inner surface 20 of the housing 18 being in engagement with the outer peripheral surface 16 of the dynamite.

The inside diameter of the housing 18 is only slightly larger than the outside diameter of the dynamite stick 12, whereby there is a very close fit between the housing and the dynamite to provide a substantially moisture-proof seal.

If desired, spaced-apart annular ridges or serrations 42 can be provided on the inner surface 20 to improve the sealing engagement of the housing 18 with the outer surface of the dynamite.

At the mine or construction site, the free end of the powder fuse 26 is connected to one end of a longer length of fuse 42 by a conventional metal sleeve 45 which is then crimped as at 43 with a crimping tool.

It will be readily apparent that when the powder fuse 42 is ignited, the burning black powder activates the detonator 28 which fires through the apertures 36 (and also bursts the tubular prong 32), thereby igniting the dynamite 12.

Referring To FIGS. 3-5, an electrical detonator assembly 45 of similar construction is adapted to be used with the dynamite stick 12 in substantially the same manner as previously described.

The assembly 45 is also preferably made from a plastic material, and includes a cylindrical housing 46 which is opened at both ends and which has a transversely extending wall 48 intermediate the ends thereof.

A detonator-receiving opening 50 is provided in the wall 48 adjacent to the inner surface of the housing, and depending from the wall 48 in alignment with said opening is a tubular prong 52 which has a pointed lower or inner end 54 with opposed apertures 56 adjacent said lower end. As in the other embodiment, the axis of the tubular prong is substantially parallel with the longitudinal axis of the housing 46.

A smaller wire-receiving opening 58 is contained in the wall 48 adjacent to the detonator opening 50.

Spaced above the wall 48 is an internal shoulder 60 which receives and supports a disc-like wiring board 62 containing electrical components which will be described more fully hereinafter, and two solder-less connectors 64 which engage the wire leads 66 and 67 of a detonator 68 which is received in the tubular prong 52 in the manner previously described relative to the detonator assembly of FIGS. 1 and 2.

A cap 70 is provided to seal the upper or outer end of the housing 46 after the detonator 68 and wiring board 62 have been positioned within the housing.

Referring to FIGS. 5 and 6, the components on the wiring board 62 include a one micro-henry choke 72 connected in series circuit with and adjacent to the detonator 68, and a one-eighth amphere fuse 74, a five micro-farad capacitor 76 and a 500-1 ,000 pico-farad capacitor 78 connected in parallel circuit across the leads to the choke and the detonator.

Extending from the board 62 (FIG. 5) are two

conductors

80 and 82, approximately 6 feet in length, which pass through the wire opening 58 in the wall 48 and thence between the outer surface of the dynamite l2 and the inner surface of the housing 46.

As shown in FIGS. 6, prior to firing, the

conductors

80 and 82 are connected through a battery 84 and a switch 86.

It will be understood that when the electrical-type dynamite detonator assembly 45 is received at the work site, the detonator 68 will have been inserted in the tubular prong 52 and the

leads

66 and 67 pressed into the solder-less connectors 64, the

conductors

80 and 82 will be extending from the housing 46, and the board 62 and the cap 72 will have been cemented in position.

As previously described relative to the embodiment shown in FIGS. 1 and 2, the detonator material such as mercury fulminate can be deposited directly into the tubular prong 52 without using a separate container, thereby further reducing the cost of the assembly.

Accordingly, with the detonator and the activator therefor being assembled in one housing, it is only necessary for the workman to press the pointed end of the prong 52 against the end of the dynamite stick, and push on the assembly 45 until the prong enters and becomes embedded in the dynamite, with the housing 48 slipping over the end of the dynamite as shown in FIGS. 3 and 4.

As in the construction previously described (FIG. 2), the inner surface of the tubular housing 46 is in close engagement with the outer surface of the dynamite, and said inner surface can be provided with spacedapart ridges or serrations 90, if desired, to increase the sealing relationship between the housing and the outer peripheral surface of the dynamite stick, and to achieve an increased moisture-proof seal.

As mentioned hereinabove, one of the major problems with prior electrical detonators is that they are prematurely activated by extraneous electro-magnetic impulses from low-flying aircraft or automotive equipment. However, with the circuit illustrated in FIG. 6, any extraneous currents above 100 cycles per second in the

conductors

80 and 82, will pass through the double-capacitor filter, without reaching the fuse 74 or the detonator 68.

Whenever it is desired to explode the dynamite, the switch 86 is closed and a surge of direct current from the battery 84 first causes the fuse 74 to melt (in less than about 5 milliseconds), and then passes through the detonator 68, causing it to be activated and to explode the dynamite.

Thus, it is apparent that there have been provided two embodiments of a dynamite detonator assembly one to be activated by a black powder fuse and the other by an electrical current which fulfill all of the objects and advantages sought therefor. Both are simple in construction and relatively inexpensive to manufacture, and provide a substantially moisture-proof and clean assembly for quickly and easily embedding a detonator in the end of a dynamite stick a I claim:

1. An explosive assembly, comprising, in combination:

an explosive charge of cylindrical configuration having an end portion and an end wall;

a rigid tubular housing with a side wall having one end thereof positioned over the end portion of the explosive charge in telescoping relationship therewith;

closure means at the other end of said housing providing a moisture-proof seal with the side wall thereof;

a tubular prong in the housing and supported thereby, said prong being embedded in the explosive charge inwardly of the end wall thereof;

explosive detonating means in said tubular prong;

and

means connected to said detonating means and extending exteriorly of said housing between the side walls thereof and the explosive charge for activating the detonating means.

2. An explosive assembly as described in claim 1 in which the tubular prong is supported by a wall which extends transversely of the housing inwardly of said closure means.

3. An explosive assembly as described in claim 1 in which the tubular prong is positioned adjacent to, but spaced from the side wall of the tubular housing, and said activating means extends from said prong to adjacent the side wall of the housing generally opposite therefrom.

4. An explosive assembly as described in claim 1 in which the explosive detonating means in the tubular prong comprises a charge of explosive material which is in direct contact with the inner surface of said prong.

5. An explosive assembly as described in claim 1 in which the means for activating the detonating means is mounted on a wall intermediate the closure means and the prong and includes two electrical conductors, a filter connected across said conductors for bypassing alternating currents, a fuse connected across the conductors intermediate the detonating means and said filter, and an electrical choke in series circuit with one conductor intermediate the detonating means and the filter.

6. A detonator assembly comprising:

a rigid cup-like housing including a side wall and a closed end, and with an open end to fit over an end of a rigid cylindrical explosive charge which has an outer peripheral surface and an end wall, with the side wall of said housing in engagement with said peripheral surface;

a tubular prong in said housing and supported thereby, the axis of said prong being generally parallel with the longitudinal axis of the housing;

explosive detonating means in said tubular prong;

and

means connected to said detonating means for extending exteriorly of said housing between said side wall and said peripheral surface, for activating the detonating means.

7. A detonator assembly as described in claim 6 in which the detonator activating means is supported on a wall within the housing and includes two electrical conductors, a filter connected across said conductor for by-passing alternating currents, and a fuse connected across the conductors intermediate the detonating means and said filter.

8. A detonator assembly as described in claim 6, in which the detonating means comprises a charge of explosive material which is in direct contact with the inner surface of said prong.

9. A detonator assembly as described in claim 6, which further includes a wall spaced from said closed end and containing electrical connectors for receiving ends of electrical conductors.

10. A detonator assembly as described in claim 6, in which the tubular prong is supported by a flange portion extending from said side wall of the housing, and which further includes a wall intermediate the closed end and said tubular prong, and electrical connectors supported on said wall for receiving ends of electrical conductors.

11. A detonator assembly as described in claim 6, which includes a wall adjacent said closed end, which wall supports said tubular prong and contains a channel extending from the prong for receiving the activating means.

12. A detonator assembly as described in claim 6, in which said closed end comprises a wall which supports the tubular prong and which contains a channel extending from said prong for receiving the activating means; and a cap member in sealing engagement with said wall and the side wall of the housing.

Claims

1. An explosive assembly, comprising, in combination: an explosive charge of cylindrical configuration having an end portion and an end wall; a rigid tubular housing with a side wall having one end thereof positioned over the end portion of the explosive charge in telescoping relationship therewith; closure means at the other end of said housing providing a moisture-proof seal with the side wall thereof; a tubular prong in the housing and supported thereby, said prong being embedded in the explosive charge inwardly of the end wall thereof; explosive detonating means in said tuBular prong; and means connected to said detonating means and extending exteriorly of said housing between the side walls thereof and the explosive charge for activating the detonating means.

6. A detonator assembly comprising: a rigid cup-like housing including a side wall and a closed end, and with an open end to fit over an end of a rigid cylindrical explosive charge which has an outer peripheral surface and an end wall, with the side wall of said housing in engagement with said peripheral surface; a tubular prong in said housing and supported thereby, the axis of said prong being generally parallel with the longitudinal axis of the housing; explosive detonating means in said tubular prong; and means connected to said detonating means for extending exteriorly of said housing between said side wall and said peripheral surface, for activating the detonating means.