US1964788A - Delay action electric detonator - Google Patents

Description

July 3, R934. J. M. COOPERY DELAY AcTrIoN EL'ECTRIC DEToNATR Filed Feb. 17'-, 1932 llllllllllllllllllllll l llllllllll lu Patented .Fully 3, 1934 i,964,7ss

DELAY ACTHON ELECTRIC DE'EONATOB James Marchbanksooper, Ardrossan, Scotland, assigner to Imperial Chemical Industries Limited, a corporation of Great Britain Application February 17, 1932, Serial No. 593,664 lin Great Britain February i9, 1931 i ci. (ci. ice-im When a delay action electric detonator functions, the following sequence of events is found: (1) The electric current from an exploder. or other source, res the electric fuse; (2) the elec- 5 tric fuse fires the delay element, and (3) the delay element fires the detonator. It can be mentioned at this point that the delay element may consist lof (a) aV metal cylinder containing pressed delay composition; or (b) lead-covered fuse; or (c) lead semi-fuse; i. e. lead-covered fuse in which the powder core is covered with spinning and countering yarn, but with no waterproofing materials; or (d) compressed or moulded composition which is positioned inthe detonator casing between the electric fuse and the detonator cap.

Between'the electric fuse and the delay element there is always a gap or space provided with one or more vents to the exterior of the debustion gases, the expansion of which would otherwise burst thecasing. When the delay action detonator begins to function both hot combustion gases and flame are produced before the delay elementuhas time to burn through to the material which is toinitiate the surrounding explosive. Suchgases and flame, if allowed to escape from the delay action detonator uncooled through the vents'will be found invariably to ignite the explosives surrounding the detonator. If gunpowder happens to be the explosive in use then a premature explosion will occur. Y

According to the invention such premature ignition, orexplosion, is prevented by masking f the gas vent or vents by means of fine mesh, e. g. SO-mesh, wire gauze,ior.wire cloth. It is to be understood that the gauze or wire cloth only masks the vent holes, and does not prevent the gases from emerging therefrom; The wire gauze, or wire cloth, may be used either in the form of a' strip 'of material wrapped outside the detonator and maskingthe gas vents externally, or it may be used in the form of a strip, or of a roll, or of a cylinder inside the detonator and masking the lay action detonator to. allow for escape of comcylinder H is an internal mask K positioned begas vents internally.' A combination of the two L methods may also be used, that is to say there the detonator surface, to affordincreased opportunity for cooling of the gases should they tend to escape between the wrapping and the detonator casing. The delay action detonator can then be embedded entirely in any explosives without any risk of a premature ignition, or explosion, of the explosives occurring.

One example of my invention is illustrated more fully in the accompanying drawing in which Figure 1 is a sectional view in elevation of a 65 detonator embracing the gas cooling means. Figure 2 is similar to Figure 1`but includes the spacing and gas cooling means on the outside of the detonator. Figure 3 is a view in cross-section of Figure 1, taken o n a line through the'exit 7u opening. andFigure 4 is a like View of Figure 2. Fig. 5 illustrates a vertical 'section showing `the application of gauze both inside and outside the tube, and, Fig. 6 shows a cross section of the same.

In Figure 1, A is the shell. or container for the Z5 fulminate-chlorate or similar composition B, and Cis the delay element comprising a metallic cyl- ,inder containing, for example, a pressed delay composition D. E is the upp`er part of the inner shell containing the electric .fuse F, and connecting with the electric wires I, and G is the waterproofing composition or mixture for sealing the upper end of the detonator. H is an outer cylinder or metal tube having a friction nt with inner casings A and E Ato` securely hold them in operative relation one .with the other. The outer cylinder H has inits side wall an exit J for the escape of gases emanating from the delay element upon ring of the detonator. Inside of the tween thelower endof the electric fuse E'and the upper end of the shell A, comprising a cylinder of wire gauze, which also functions as a spacing element between the upper and lower sections E and A of the detonator element.

In Figure 2 an external mask L is shown -which not only acts as a cooling means for the gases escaping through the exit J, butspaces the heated portion of the detonator from the explosive in which the detonator is embedded.

Since the metal containers of the various elements of the complete delay action detonator are commonly made in friction nt pieces, the width of the wire gauze as in the above example can provide a convenient method of predetermining the distance between the electric fuse and the delay element. The detonator described in the above example is suitable for initiating black powder.

AS many apparently Widely different embodi- 1151i ments of this invention may be made without departing from the spirit and scope thereof, it is lto be understood that I do not limit myself to v the specific embodiments thereof except as de- Ined in the appended claims.

I claim:

1. A delay action electric detonator having gas escape means in the portion of the casing between the electric fuse and the delay element, and gas cooling means between said fuse and delay element, comprising a metal gauze.

2. A delay action electric detonator having gas escape means in the portion of the casing between the electric fuse and the delay element, and an internal cooling means holding said fuse and delay element in spaced relation, comprising a metal gauze.

3. A delay action electric detonator having gas tively Wide area of the detonator casing to space l it from the explosive in which it is embedded and to accord increased opportunity for cooling of the gases should they tend to escape between the wrapping and the casingi JAMES MAECI-[BANKS COOPER.

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