DE2043945A1 - Electric explosive tinder - Google Patents

Description

Case Nippon Kogei-6.

1 A- 187.

Nippon Kogei Kogyo Company, Limited

Electric detonator

The invention relates to an electric detonator

with a pair of electrostatically insulated ignition wires ;. λ

a fuse head and a primer.

Such electric detonators are already known. In However, the past encountered numerous unexpected ones Accidents due to uncontrolled ignition and exploding of the explosives. These uncontrolled ignitions are based on electrostatic discharges, which are caused, for example, by friction with clothing, dust or the like will"

In tunneling, for example, one method of removing suspended particles and dust is to charge the particles by means of a strong electrostatic charge between the tunnel wall and an electrode. In such a dust removal operation, conventional detonators will experience numerous accidental explosions of the explosive in the area concerned. These explosions are based on electrostatic discharges between the ignition head and the ignition cap of the ignition-acx-a through electrostatic induction. ·

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Thus, it is the object of the present invention to provide an electric detonator which against Ignitions by accidental, artificial friction, natural friction by dust, electrical induction from the sparks of electrical devices or trains or due to the electrostatic influence during removal discharges caused by suspended particles from the tunnel atmosphere are completely secured.

This object is achieved according to the invention in that at least one of the two ignition wires is in the insulation at least one of the primer or a component electrically connected to the primer opposite Passage is provided so that a possibly between of the primer and at least one of the primer wires formed high electrostatic potential across the passage discharges.

According to the invention, a holder can also be provided, which the ignition head at a safe distance from the Holds primer, and which also supports the insulated primer wires and holds them in place.

The ignition head can be of the bridge igniter type, in which the current is transferred through a glow wire, which is immediately surrounded by easily flammable substances, as well as the type of gap igniter, which has more or less conductive substances in the primer take over the power line.

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The invention is explained in more detail below with reference to drawings and examples.

Show it

FIG. 1 shows a longitudinal section through a conventional igniter;

FIG. 2 shows a longitudinal section through a preferred embodiment of the igniter according to the invention and

Figure 3 is a schematic representation of various measurements methods to give away the insulation of the ignition wire according to Figure 2 with passages.

The inventive electric detonator for explosives I

is thawed in such a way that the detonator head is electrostatic is isolated from the inner surface of the primer by placing between the primer and the primer head a predetermined distance is maintained and by covering the ignition head with an electrostatic isolator, e.g. shielded by an insulator with a resistance of 2000 KOhm / mm is. There are one or more passages in the electrostatically insulating sheath of the ignition wires provided so that substantially all of the static electricity, if any, is removed from the detonating wires is discharged towards the primer.

It is especially beneficial when looking for the fuse head a holder provides that the firing head in a predetermined Distance from the primer. It has also been found beneficial if the bracket is shaped in this way is that the insulated ignition wires of the detonator are kept in contact with the outer capsule of the detonator, although of course many other forms of mounts

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- 4 can be applied.

The bracket can, for. Consist of an electrostatic insulator such as a polyolefin resin, a Polyvinyl resin or other plastic materials. Further In certain cases, the holder can be made of a metal, for example, which is connected to the primer is in communication and is arranged so that the passages of the ignition wires face the bracket. In the case of a metal bracket, however, the The ignition head must be electrostatically separated from the holder.

It should also be noted that the detonator head can be shielded by removing the outer capsule in the area of the ignition head with a coating of e.g. epoxy resin, polyvinyl resin or the like. Further The passages of the primer wires should be arranged in such a way that they connect to the primer or one with the primer connected component opposite.

The ignition head can be shielded by covering it directly with an electrostatic insulator or wrapped such as an insulator made of rubber, polyvinyl resins, polyolefin resins, polyester resins or the like. The insulator should preferably have a dielectric strength of more than ten times the dielectric strength Have the strength of the air.

The passage or passages which are appropriately spaced from the firing head in predetermined areas of the Sheathing of the two ignition wires are provided, can easily by handling, by knife cuts, by electrical Discharge, melting, chemical etching or the like. Be formed. Am such a

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gangway, the "Goebo.1t" can have an invisibly fine hole. Any static electricity that is applied to the two ignition wires can be discharged through the passages to the capsule, which in turn is connected to Hv <lc . ,

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It must be noted that usually a majority of Explosive rods or cartridges are connected in series. Thus, the two ignition wires the multitude of explosive rods or cartridges connected in series and if random If one of the ignition wires is grounded according to the present invention, the explosive will not be ignited. the thin passages in the sheath of the wires are formed in such a way that grounding is avoided and that on the other hand, any static electricity is discharged through these holes or passages. When an electrostatic charge is generated and attached to the ignition wire accumulates, so will the air in the appropriate passages ionized so that between the wire and the primer a discharge takes place through these passages. It must also be noted that a smooth Electrostatic discharge occurs when the passageways are small. If, on the other hand, the passageways are large, an intermittent discharge occurs. It has been found that electrostatic discharge is preferable should run smoothly. It is also important that the electrical current not pass through any of the passages closes in the wire cover. It is sufficient if £ in passage in a wire sheath opposite the Primer or a component connected to the primer Advantageously, however, every ignition wire has in the casing has a passage which is opposite the primer or a component connected to it.

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To shorten the distance between the primer an ignition wire in the area of a passage, a holder is provided which holds the wire in such a way that the The insulation shell of the same in the area of the passage is in contact with the primer. Preferably im Area of the passage a metal plate can be wrapped, which in turn connects to the primer stands. On the other hand, the passage can be arranged so that it faces a conductor or a semiconductor, which in turn is connected to the primer.

According to the invention, the ignition head can be electrostatically isolated by isolating a holder from a * - the material used. The ignition head can also be electrostatically isolated from the capsule by using a Inserting insulator into the primer by coating the primer itself with an insulator by inserting wrapped an insulator around the ignition head or by other suitable means.

In the drawings, the same reference symbols denote identical or corresponding components. In Figure 1, a conventional electric igniter is shown, which has a capsule made of copper. A propellant charge 2, an initial explosive 3 and a delay powder 4 are provided in the capsule. The initial explosive 3 is located in an inner tube 5. A detonator 6 is provided between the ends of wires 8 and 8 '. These wires have a sheath made of insulating material 7 and 7 ¹ . The ignition head further comprises an ignition wire 9 which is connected to the ends of the wires 8 and 8. Furthermore, the ignition wire 9 is surrounded with a filler. The ignition head 6 is at some distance from the delay powder 4 by the insulated wires 7 and 7 ^1.

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keep. The insulated wires 7 and 7 'are supported by a * ¹ sealing plug 10 seated in the capsule 1 in position.

In Figures "-2" is a preferred embodiment of the present Invention shown, the squib 6 of a bracket 11 is held in position. The holder 11 serves the ignition head 6 at a certain distance to keep from capsule 1. Both insulated wires 8 and 8 'are also held by the holder 11 in such a way that each of the insulating sheaths in the area of Passages 12 in the insulation of wires 8 and 8 'with the capsule 1 is in contact. If the holder 11 has a parabolic shape around the ignition head 6, in this way, upon ignition, the energy of the ignition head 6 is uniformly transferred to the retardation powder.

As illustrated in Figure 3, the passages in the insulating sheath 7 of the wire 8 has the shape of a pinhole 13, which by entering a tfadel 14, or by a high voltage discharge from a needle electrode 14 connected to a high voltage generator 15 is can be generated. Alternatively, a passage in the insulating sheath 7 of the wire 8 by means of a knife 17 or in numerous other ways, such as by rather: .- sches Etching can be generated in the form of a slot. In the capsule 1 there is also the propellant charge 2, the ignition means 3 and the retardation powder 4, although these parts are not shown in FIG. "

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The ignition head 6 according to Figure 2 can be electrostatically isolated from the capsule 1 of the igniter by wrapped or coated with an insulating material. Alternatively or additionally, the ignition head 6 can be opposite of the capsule 1 can be electrostatically isolated by placing the inner surface of the capsule 1 in the vicinity of the ignition head coated or clad with insulating material. It must be noted that the passages 12 necessarily either the capsule 1 or a component which is electrostatically connected to the capsule 1 stands opposite. However, the present invention is not limited to a specific holder 11. Rather, the holder 11 can be completely eliminated if the ignition head 6 is electrostatically removed from the capsule ΐ is insulated and if the passages 12 either of the capsule 1 or a component connected to the capsule 1 opposite. Thus, the area around the passages 12 can be covered with a conductive or semiconductive material Form of a powder or a paint are filled so that the passages 12 face an electrostatic with the Capsule 1 connected component lie.

In the following, the invention is explained in more detail with the aid of exemplary embodiments.

In each of the following embodiments, both ignition wires were connected to the through a 500 megohm resistor negative connection of a negative direct current high voltage generator with a voltage variable from 0 to -120 kilovolts connected. The positive connection of the generator and the cap are earthed. When increasing the negative With a voltage of the generator from 0 to -120 kilovolts, the ignition voltage of the ignition head of each igniter is tested. The voltage applied to test the ignition of an ignition head is measured. A detonator, which not ignited at a voltage of -120 kilovolts is given the sign X.

109885/1061 ' ⁹ '

example 1 Test specimen;

(A) As a control specimen, 15 conventional electrical Detonators with a copper capsule 6 mm in diameter selected at random. / ■■■ -.

(B) Another 15 copies of the same fuse type were statistical selected and a pinhole was made in a detonating wire the same by means of a 0.3 mm diameter thread stabbed. The position of the needle hole was chosen so that it was opposite the detonator capsule and a holder was used to keep the detonator head at a distance from the capsule keep. In the table below, d means the distance between the ignition wire at the pinhole passage and the Inner surface of the capsule. 1 is the distance between the surface of the firing head and the passage. In this example applies d = 1 mmj 1 = 6 mm.

(C) There were another 15 detonators of the same type statistically was selected and the ignition wire was cut into the sheath by a knife. The knife had a cutting edge 0.95 mm thick and the slit faced the capsule. The values d = 1mm and 1-6 mm applied.

The results are compiled in the following table.

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(A) Sample No. 12 3 4 5 6 7 8

Applied ignition voltage (-KV) 80 100 60 1.20 120 5 92

Ignition OOOXXOO X

Room temperature: 23 ° C; Humidity = 56 fo;
0: ignition; X: no ignition;

(B) Sample Fo. 12 3 4 5 6 7 8

Applied ignition voltage (-KT) 120 120 120 120 120 120 120

Ignition XX X X X XX X

d = 1mm; l = 6mm; Room temperature: 24 ° Oj Humid 50? 6; 0: ignition; X: no ignition.

(C) Sample No. 12 3 4 5 6 7 8 Increased ignition ~

voltage (-KV) 120 120 120 120 120 120 120

Ignition XXXXXXXX

d = 1mm; l = 6mm; Room temperature? 26 ° C; Humidity: 51 $> \ 0: ignition; X: no ignition;

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(A) Sample No. 9 10 11 12 13 14 15

Created
Ignition voltage
(-KV) 40 40 20th 120 11 12th 30th 30th 30th ignition O 0 0 X 20th 120 0 0 0 Room temperature O: ^r C; Humidity =
Ignition; X: none X X = 56 #;
ignition (B) Sample No. 9 10 13th 14th 15th Created
Ignition voltage
C-KV) 120 120 1 120 120 120 ignition X X X X X

d = 1 mm; 1 = 6 mm; Room temperature: 24 ° C; Humidity: $ 50; Oi ignition; X: no ignition.

Sample No. 9 10 11 12th 13th 14th 15th Created
Ignition voltage
(-KV) ■. . . . 120 120 120 120 120 120 120 Bundling X X X X X X X d = 1 mm; 1 = 6 mm; Room temperature: 26 ° C; Humid

speed! 51 #; 0: ignition; X: no ignition.

In the test series (A) it can be seen that 70 $> of the tested detonators were ignited after applying a voltage of less than -100 KV. This shows a high probability of accidents with the conventional detonators due to ignition by an electrostatic effect. On the other hand, none of the detonators in test series (B) and (C) was ignited even with an applied voltage of - 120 KV. This shows that the detonator according to the present invention for the prevention of accidents by the above

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prevents electrostatic ignition in an effective manner.

Example 2

The tests with the detonators according to the test series (B) were repeated around the influence of the distance between the surface of the primer and the passage in the wire cladding to prevent electrostatic discharge to investigate induced ignition of the firing head. The distance from the inner surface of the capsule to the passage in the Wire wrap has been changed, however. The following values were valid: d = 2.5 mm and 1 = 8 mm. The following results were obtained achieved:

(D) Sample No. 1 2 3 4 5

Applied ignition voltage (-KV) 120 10 80 20 10

Ignition X 0 0 0 0

Room temperature: 24 ° C / Humidity: 50 # «

The same tests were repeated with the detonators according to the test series (C), with the distance between the The inner surface of the capsule and the wire covering in the area of the slot opening was changed. The values counted d = 2.5 mm and 1 = 8 mm.

The following results were achieved:

(E) Sample No. 12 3 4 5

Created "Zünd ^ · '~

voltage (-KV) 120 10 30 120 43

zündu ^ "" "LT" "1 '" Z-ZJf-' "Zp. '. ρ" Ζ.? Z Zo

Room temperature: 26 ° Cj Humidity: 51 #.

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When comparing the test series (B) and (D) as well as the Series of experiments (C) and (E) can easily be found that the distance d of the wire from the capsule is a substantial one Effect on the ignition. Ea must therefore be stated that at a distance d above the specified limit a complete security against ignition of the Ignition head cannot be expected due to electrostatic induction. All for the test series (B), (O) -, Primers used in (D) and (E) had one. Diameter of 6 mm. SOmit was in experiments (B) and (C), where d = 1 mm, the exposed wire area of the capsule surface closer than the fuse head. In the case of samples (D) and (E) with d = 2.5 mm, however, the ignition head was on the capsule surface closer than the exposed wire area.

Accordingly, in experiments (B) and (C), the potential gradient between the exposed wire area and the

higher
Capsule surface / as the potential gradient between the ignition head and the capsule surface, so that a discharge leads to an increase in the potential between the exposed wire area and the capsule surface. In samples (D) and (S), however, the potential gradient between the exposed wire area and the capsule surface is less than the potential gradient between the ignition head and the capsule surface, so that a discharge takes place between the ignition head and the capsule surface. det. It can be clearly seen that in the latter case the effect of preventing an ignition caused by electrostatic induction is lost.

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According to these results, the distance d between the exposed wire and the surface of the squib should be large be low in order to completely avoid accidental ignition of the ignition head. Accidental ignition can cause electrostatic induction can be effected even if the ignition head is electrostatically isolated from the capsule, for example by using a shield, coating or wrapping with insulating material falla the pinhole or the slot in the wire covering does not face the primer or if the distance d is too great.

Example 3

Then the influence of the size of the slit or dee Pinholes in the wire wrap for the ability to prevent ignition by electrostatic induction checked. The slot width of the test series (C) was changed to 0.5 mm and 1 mm. This series of experiments was repeated with these values. There was no ignition of the samples and therefore no effect on the Variation of the slot width found. To check the influence of the hole size, especially holes with With a diameter of less than 0.3 mm, the hole was made by means of an electrical discharge in a wire covering of a detonator (B). The thickness of the wire wrap was 0.3 mm. The samples were found to be affected by discharge under an applied voltage hole generated by more than 60 KV did not lead to inflammation. However, when the samples are under tension of less than 40 KV were treated, such an ignition prevention effect was noticeable. Because the size the duroh electrical discharge created holes from the

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Dioke and the properties of the insulating jacket the ZunddrShte and the size of the applied voltage depends, the experimental data are only exemplary.

The samples (B) with openings created by needles were sure they made however due to the discharge in between the exposed wire area and the capsule a brush-like noise, on the other hand, lalls through the passages electrical discharge with 60 KV were produced, so the detonator was also secure, but it turned up between the exposed wire area during discharge and the capsule emits a continuous sound.

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Claims (1)

- 4b - PATENT CLAIMS 1. Electric detonator with a pair of electrostatically insulated detonation wires, a detonator head and a detonator Ignition capsule, characterized in that at least one of the two in the insulation (7) Ignition wires (8) at least one of the ignition capsule (1) or one electrically connected to the ignition capsule (1) Component opposite passage (12, 13, 16) provided is, so that a possibly formed between the ignition cap (1) and at least one of the ignition wires (8) high electrostatic potential across the passage (12, 13, 16) discharges. 2. Electric detonator according to claim 1, characterized marked that isolation (7) at least one of the ignition wires (8) with the ignition cap (1) or a component that is electrically connected to the primer (1). 3 » Electric detonator according to one of claims 1 or 2, characterized by a holder (11) to hold the ignition head (6) inside the ignition cap (1) at a given distance from the inner surface of the ignition cap (1). 4. Electric detonator according to claim 3, dadur ch characterized in that the holder (11) holds the ignition wires (8) in such a way that at least one passage (12, 13, 16) opposite the primer (1). 109885/1061 5. Electric detonator according to one of claims 3 or 4, characterized in that that the holder (11) surrounds the ignition head (6) with a parabolic shape, Bi- electric detonator naph one of claims 1 to 5, characterized in that the passage (12, 13, 16) is produced by piercing with a needle (14). 7. Electric detonator according to one of claims 1 to 5, characterized in that - _f that the passage (12, 13, 16) is produced by slitting with a knife (17). 8. Electric detonator according to one of claims 1 to 5, da durchgeke η η ζ e ic h η et that the passage (12, 13, 16) is generated by chemical etching. 9. Electric detonator according to one of claims 1 to 5 »dadurchgek β η η ζ eich η et - ₉ that the passage (12, 13, 16) is generated by electrical discharge. 109885/1061 A2 Blank page