CS228107B2 - Detonating bickford fuse with low energy,method of its manufacture and equipment for making same - Google Patents

Abstract

The improved low-energy detonating fuse is lightweight, flexible, strong and non-conducting. It detonates at a high rate and is adapted to modern rapid production methods. It has a continuous core (2) made of deformable, bound explosive containing a crystalline high-explosive compound, preferably fine-particulate pentaerythritol tetranitrate mixed with a binder. The crystalline, high-explosive compound is present in an amount of approximately 0.1 to 2 g/m. The core is surrounded by a plastic protective sleeve (4) which is approximately 0.13 to 3.18 mm thick. Preferably the binder-containing explosive core is reinforced at its circumference between the core and the plastic sheath by at least one yarn strand (3); in particular the fuse contains a core reinforcement consisting of at least one endless yarn strand at the circumference of the core and extending virtually parallel to the longitudinal axis of the core, the reinforcement having a tensile strength such that the core is prevented from contracting to the yield point under the effect of the forces normally occurring during charging of a borehole. <IMAGE>

Description

BACKGROUND OF THE INVENTION The present invention relates to a low energy detonating fuse, a method for producing the same and an apparatus for carrying out the method. A detonation fuse is used to transfer detonation to a tear charge.

The hazards associated with the use of electrical firing systems, i.e., the risk of premature firing by stray or external electrical energy, such as lightning, static electricity and electrical current of galvanic origin, stray currents, radio transmitters and transmission from trunk lines, are well known. For this reason, non-electric firing by means of a suitable detonator or fuse is considered a prospective solution. A conventional detonation fuse has a nominal detonation velocity of about 6000 m / sec. and consists of a core containing 6 to 10 g of pentaerythrite tetranitrate (PETN) per meter of length, which is covered by various combinations of materials, for example, water-impermeable textile materials, plastics and the like. However, the intensity of noise arising from detonation of a detonating fuse with such a content of pentaerythrite tetranitrate (pEtN) on the ground surface, for example in trunk lines, is often unacceptable in blasting operations in populated areas. In addition, the detonation energy of such a detonation fuse may be sufficient for the detonation pulse to be transmitted laterally to adjacent sections of the detonation fuse or to a tear charge mass around which, for example, the detonation fuse runs. In the latter case, the detonation fuse cannot be used to launch a detonation charge at the bottom of a well (the so - called ignition technique at the bottom of a well),. which is sometimes required.

In order to cope with the noise and high detonation energy problems of said detonating fuses containing 6-10 g of pentaerythrite tetranitrate per meter of fuse length, low energy detonating fuses have been developed. These detonating fuses have an explosive core containing only about 0.02 to 2 g of explosive per meter of length, most typically only about 0.4 g per meter of length. Such a detonation fuse is characterized by low detonation energy and low explosion noise intensity, so that it can be used as a stem line when the noise is to be limited to a minimum value and as a vertical line in the case of blasting charges on the bottom of a well.

The low energy detonation inflammation disclosed in U.S. Pat. No. 2,982,210 comprises a continuous detonator-sensitive granular explosive core, for example pen228107 taerythrite tetranitrate, which contains 0.02 to 0.4 g explosive per meter of length. The core is enclosed in a metal sheath, which may be covered with a fabric cover or a plastic cover. At this low explosive content, the metal shell is reportedly important for the propagation of detonation in the explosive core.

Low-energy detonating fuses fitted with a metal sheath are not suitable for continuous production in unlimited lengths and are conductive as a result of this metal sheath. Therefore, attempts have been made to eliminate this metal sheath and to find a way to replace its effect. However, these attempts have not always achieved full success, especially in the case of detonating fuses with an explosive content in the core of about 0.4 g per meter of length or less. For example, U.S. Patent No. 3,125,024 states that even detonation velocities can be achieved with a granular pentaerythrit tetranitrate core of 0.32 to 2 g explosive per meter of distance without the use of a metal sheath if the specific surface area of the pentaerythrit tetranitrate is approximately from 900 from 3400 cm ² per gram and the granular core is enclosed in a woven sheath enclosed in a protective and reinforcing cover, for example a thermoplastic layer, or in another sheath of waterproof and reinforcing material. However, woven or wound sheaths are applied in a relatively costly manner, both in terms of the required machinery and due to the low production rate of the detonating fuse. In addition, even with a high specific surface area of pentaerythrite tetranitrate and the constraints associated with the woven fabric sheath and thermoplastic cover, a high detonation rate is not reliably achieved when the pentaerythrite tetranitrate content is near the lower limit of said range.

British Patent No. 815,534 and U.S. Patent No. 3,311,056 disclose low energy detonating fuses whose explosive core is housed in a polymeric sheath. British Patent Specification No. 815,534 discloses a detonating fuse with a granular core of finely divided explosive and a content of 0.4 to 3 grams of explosive per meter of length enclosed in a flexible sheath of thermoplastic polymer which can be wrapped with fabric and veins enhancing its strength and abrasion resistance. The detonation fuse disclosed in U.S. Pat. No. 3,311,056 is a very solid type of detonation fuse, which is conditioned by a thick sheath of elastomeric polyurethane in which the explosive core is enclosed. The ratio of the amount of explosive in grams per meter of length to mantle thickness in cm is less than 11/1, preferably in the range of about 0.8 / 1 to 8/1. The contents of the core explosive in the range of 0.2 to 80 and preferably 0.4 to 20 g / m in length are described, so that said patent discloses both a high energy detonation fuse and a low energy detonation fuse. In the disclosed detonating fuse having an explosive content of 0.4 to 4 grams / m, the core of pentaerythrit tetranitrate is enclosed in a lead jacket. Although explosive cores made of self-supporting components used in leaf explosives, i.e. the explosives described in U.S. Patents 2,292,087 and 2,299,743, are described, low energy detonating fuse cores of 1-2 g explosive per meter of length are made of granulated explosives. The cores are enclosed in lead shells, the ratio of explosive contents to polyurethane sheath thickness is low (0.4 and 1.7 g explosive per meter length per centimeter sheath thickness).

U.S. Pat. No. 3,384,688 discloses the manufacture of a textile-coated detonating fuse having increased sensitivity to side ignition and increased ability to transmit detonation at a low explosive content in the core, which is achieved using particularly finely divided granular pentaerythrite tetranitrate in an amount of 2. g · per meter of detonation fuse length. U.S. Patent 3,382,802 is required in the largest particle size of 100 _(microns, at least half of the particles are less than 50 for the explosive used in the core containing from 1 to. 2 g of explosive per meter, which is enclosed in a housing of a spiral elements made of metal or of thermoplastic material, in spiral-wound sheaths and in an outer casing of thermoplastic material.

It is apparent from the aforementioned patents that granulated explosives are exclusively used for detonating fuses with cores containing 2 g of explosive per meter of length or less. In addition, a metal or heavy textile jacket is recommended in most cases, especially when the explosive content is less than 0.4 g per meter length. The self-supporting explosive mixture in which the crystalline explosive component is mixed with the binder can be extruded in the form of a fuse at high speed, which, compared to the production speeds achievable in the manufacture of granular core detonating fuses, allows a higher production rate. In addition, the cemented explosive composition has a high density and may explode at a higher rate at a given diameter compared to lower density explosives. However, since the sealed explosive compositions contain less sensitive materials, these compositions are less sensitive to ignition than whole explosive granulated compositions and it is not expected that these sealed compositions will always explode under the same conditions as the granulated compositions. Therefore, although in US Pat. No. 311,056 discloses detonating fuses with cemented explosive cores, low explosive content cores consisting of pentaerythrit tetranitrate and lead azide with aluminum and are also armored with lead. It is therefore known that in the case of self-supporting leaf explosive

With the mixture by which the explosion is to be propagated at a high uniform speed, the diameter of the fuse and the explosive content of the fuse must be sufficiently high. U.S. Pat. No. 2,992,087 discloses the manufacture of a fuse by extruding pentaerythrite nitrocellulose-based pentaerythrite tetranitrate up to a content of 4 g of explosive per meter of length which detonates at a rate of over 6400 m / sec. U.S. Pat. No. 3,311,056 discloses sealed explosive cores containing 3.7 and 4 g of pentaerythrite tetranitrate per meter of length. However, detonated fuses with cemented explosive cores containing 2 g of explosive per meter of length or less are not described, although detonation fuses with granular pentaerythrit tetranitrate may work at these low explosive contents. U.S. Patent Nos. 3,338,764, 3,401,215, 3,407,731, and 3,428,502 disclose the production of a detonating fuse containing 10 to 40 grams of explosive per meter. The manufacture is carried out by extruding an explosive mixture cemented with a flexible elastomer, preferably around a centrally located reinforcing fiber or vein. Wrapping the extruded core with reinforcing bundles or fabric from the outside, for example a braided structure, and bonding bundles in the core using a latex or liquid polymer are said to be less suitable than the internal reinforcement elements.

In the manufacture of detonating fuses, fibers are also used to facilitate sheathing of powder explosive cores. U.S. Pat. No. 3,683,742, for example, describes the circular guidance of one or more of the roughened fibers through a hopper, through which a powdered explosive is fed into a casing continuously manufactured at the bottom of the hopper. The fibers are deviated from the vertical axis of the hopper and fed into the housing along with the explosive. The fibers pull down the powder explosive and introduce it into the sheath so that a granular explosive core is formed around the inner fiber.

British Patent Specification No. 1,416,128 and Belgian Patent Specification No. 815,257 disclose inserting a dry powder explosive column into a sheath composed of axially extending and interconnected fibers and introducing the fiber explosive column into a press apparatus where the fibers are simultaneously stretched, so that the core of the detonator is formed. The core thus formed, in which the explosive is surrounded by an envelope of fibers, is then wrapped with a reinforcing layer of wound textile material, which is protected by a waterproof plastic layer.

U.S. Pat. No. 2,687,553 discloses the use of longitudinal fibers reinforcing detonating firing pins and a sheath of thermoplastic material which is itself conventional. The resulting detonating fuse consists of an explosive core enclosed in a sheath of thermoplastic material in which long fibers are deposited in the longitudinal direction. The entire periphery of the explosive core is in direct contact with the sheath of thermoplastic material and the fibers are surrounded by the thermoplastic material.

The disadvantages of the known detonation fuses are eliminated by a low energy detonation fuse consisting of a continuous solid core of a detonation explosive, reinforcing elements of the core and a protective sheath covering the core and reinforcing elements according to the invention in that the explosive is a malleable explosive mixture. Containing at least 55% by weight of a detonator-sensitive crystalline explosive component selected from the group consisting of organic polynitrates and polynitramines mixed with a binder, the largest particle size of the crystalline explosive component in the binder is in the range 0.1 to 50 μηι and the core contains 0.1 to 2 g of the crystalline explosive component per meter of length, the reinforcing elements are arranged outside the core and the protective sheath consisting of at least one layer is of plastic material, which is ductile at a temperature not exceeding the melting point of the crystalline explosive component more than 75 ° C ..

The core reinforcing elements are formed by at least one continuous fiber bundle disposed on the periphery of the core and extending approximately parallel to the longitudinal axis of the core, the fiber bundle having a core elimination strength under the forces commonly encountered when inserting into boreholes to an unacceptable failure rate.

The core reinforcing elements consist of at least four fiber bundles distributed uniformly over and adjacent to the periphery of the core, the fiber bundles having a tensile strength of at least 44 N with the core and surrounded by a protective sheath together with the core.

Also preferred is an embodiment in which the fiber is multiple and its living is distributed around the core.

The crystalline explosive component of spring is preferably selected from the group consisting of pentaerythritol tetranitrate and cyclotrimethylenetrinitramine, and the explosive composition comprises at least 70% by weight of pentaerythritol tetranitrate, the core comprises at least 0.4 g pentaerythritol tetranitrate per meter of length and the protective sheath is thermoplastic material.

The binder of the explosive mixture is preferably plasticized nitrocellulose.

The thermoplastic sheath material is a polyolefin that is malleable at temperatures up to 200 degrees C, for example polyethylene, and the wall thickness of the sheath is in the range of 0.051-0.127 cm.

An embodiment in which the wall thickness of the protective sheath is in the range of 0.013 to 0.318 cm is preferred.

The drawbacks of the known detonating fuses are eliminated by forming a detonating fuse by molding a continuous core from a detonation explosive and applying a protective sheath to the core of the invention, which is characterized in that the core is formed from a detonator-sensitive crystalline explosive component with a binder. the fiber bundles are pulled to form a moving screen roller with approximately parallel longitudinal bundles between which a core carried by the screen roller is introduced without changing the diameter, onto which a layer of soft plastic is applied and subsequently cured.

The core is extruded into the net roller and the plastic net is extruded around the net net roller, or the net net roller is wrapped around a plastic tube, for example by conducting a net net roller with a current. a protective sheath around the net cylinder with the core.

The core is vacuum-formed from the detonation explosive and particles larger than 25% of the core diameter are removed from the detonation explosive.

The deficiencies of the known detonating fuse manufacturing apparatus are eliminated by a device consisting of a continuous solid core production device from a detonation explosive and a protective coating device on the core according to the invention, which consists of a first extruder for shaping a mass of the malleable explosive mixture into a continuous solid core, from the device for orienting the fiber bundles into a circular arrangement in which the fiber bundles are approximately parallel to each other. Further, from the tensioning device for approximately parallel fiber bundles by a tension sufficient to form the fiber bundles into a moving screen cylinder, the fiber bundle orientation device being arranged relative to the first extruder such that the screen cylinder surrounds and entrains the core projecting from the first extruder, a second extruder for applying a soft plastic in the form of a sheath to a substrate passing through the second extruder, wherein the second extruder and the fiber bundle orientation device are arranged such that the core provided with a mesh roller passing through the second extruder is the substrate , wherein there is no previous, continuous or subsequent reduction of the core diameter and finally from the plastic hardening vessel provided with the core provided with mesh roller and sheath.

The first extruders are provided with an extrusion chamber provided with a suction tube for applying vacuum.

In the extrusion chamber, a device is provided for separating particles having a dimension greater than 25% of the core diameter from the core.

Preferably, the first extruder is provided with a plunger extruder comprising a heated chamber.

A sensing device of the operation of the first extruder for controlling the fiber bundle tensioning device is connected to the first extruder and the fiber bundle tensioning device.

A new and higher effect of the invention is that detonating fuses detonate without interruption while all the sheath material is digested. The average detonation speed of all detonation fuses is 7300 m / sec.

In the manufacturing process according to the invention, there is no significant change in diameter after the core has been formed. This produces a high-density core which does not need to be reduced in diameter, as is the case, for example, in the manufacture of detonating fuses with granular explosive cores. Eliminating core diameter variations during manufacture simplifies production control with a view to achieving the desired final explosive content in the core and prevents the fiber bundles surrounding the core from entering the core.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 and 5 are partial axial sections of various embodiments of a detonating fuse according to the invention; FIG. 2 is a schematic of a device according to the invention; and FIGS. various embodiments of parts of the apparatus shown in FIG. 2.

FIG. 5 shows a cross section of a low energy detonation firing pin 1. In this section, a continuous solid core 2 of a ductile cemented explosive mixture, for example a very fine pentaerythrite tetranitrate mixed with a binder, for example plasticized nitrocellulose, is visible. The diameter and the content of the explosive in the core 2 are such that approximately 0.1 to 2 g of the explosive is located within one meter of the length of the detonating fuse 1. Further, FIG. 5 shows a protective grip 4 of approximately 0.127 to 1.905 mm thick surrounding the core 2.

FIG. 1 also shows a cross-section of a detonating firing pin 1 in which the core 2 is surrounded by reinforcing elements 3 consisting of fibers composed of multiple fibers. These reinforcing elements 3 abut the periphery of the core 2 and extend parallel to the longitudinal axis of the core 2. Thus, the protective sheath 4 covers the core 2 and the reinforcing elements 3 of the core 2. In one part of FIG. Also in part of FIG. 1, the protective sheath 4 is removed so that the arrangement of the reinforcing elements 3 on the core 2 is evident and, after removal of the reinforcing elements 3, the shape of the periphery of the core 2.

The low energy detonating fuse 1 according to the invention is a combination of a continuous solid core 2 of a ductile cemented explosive mixture of low explosive content per meter of length, i.e. 0.1 to 2 g per meter of fuse length, and a lightweight protective sheath 4 of plastic covering the core. 2. A malleable explosive mixture consists of a crystalline explosive bonded by a binder. Another feature of the detonation fuse 1 according to the invention is the outer longitudinal reinforcement of the core 2 by the reinforcing elements 3. It has been found that a low energy detonation fuse 1, contrary to the prior art, can reliably transmit the detonation at blasting speed, i.e. above 4000 m / sec. even if the content of the explosive in the detonation fuses is below 1 to 2 g per meter of length of detonation fuse 1. There is no need to enclose the detonation fuses 1 into a metal or braided textile sheath, spirally wound textile material, plastic or metal fiber bundles or thick plastic sheath. It has been found that said sheathing is necessary when the core 2 consists of a continuous solid rod of a cemented explosive, for example a plastic-filled explosive, containing at least about 55% by weight of the explosive and a "very fine" crystalline explosive component. and if there are no reinforcing elements at the periphery of the core 2. In the detonation firing pin 1 of the invention, the explosive particles in the core 2 are bound to each other by a binder, e.g. a blend of organic polymers, which has been found to favorably ensure uniform high density. which increases the reliability of detonation. The high density of the core 2 is particularly important in detonating fuses 1 of small diameter and low explosive content. With respect to the sealed core 2, it has been found that the central internal reinforcements recommended in high explosive detonating igniters made from self-supporting explosives - see U.S. Pat. No. 3,338,764 - can be in the case of low explosive detonating fuses with a core of this explosive. In this case, the cemented explosive core 2 of the detonating fuse 1 according to the invention is reinforced. The outer elements 3, for example textile fibers, preferably extend longitudinally. This construction of detonating fuse 1 'is particularly suitable for manufacturing on continuously operating high speed production machines, which is not possible in the case of low energy detonating fuses according to the older embodiment with woven or wound textile stiffeners.

The cemented explosive mixture constituting the explosive core 2 of the detonating fuse 1 comprises at least one finely divided detonator-sensitive crystalline explosive component, which may be an organic polynitrate, for example pentaerythrite tetranitrate or mannithexanitrate, or a polynitramine, for example cyclotrimethylenetetriamine. Of these, pentaerythritol tetranitrate is the most available, the properties of which are satisfactory when used under conditions typically encountered in blasting operations. For these reasons, the use of pentaerythrite tetranitrate in the cemented explosive core 2 is preferred.

The crystalline explosive component is mixed with a binder, which may be, for example, soluble nitrocellulose described in U.S. Patent No. 2,992,087 or a mixture of organic rubber and a thermoplastic terpene hydrocarbon resin disclosed in U.S. Patent No. 2,999,743. The publications may be used to manufacture the core of the detonating fuse of the invention, and the reader refers to the descriptions of these patents. Other additives may also be present in the compositions, for example additives used to plasticize the binder or to thicken the composition. Other useful compositions are those described in U.S. Patent Nos. 3,338,764 and 3,428,502, the disclosures of which are also incorporated herein by reference.

The detonation fuse 1 according to the invention is the so-called "low energy" detonation fuse, that is to say detonation fuse 1, which produces a relatively low noise and a relatively low explosive energy during detonation. The diameter of the core 2 is therefore at a given composition. of the core 2 such that 0.1 to 2, preferably about 0.4 g of the crystalline explosive component is contained in the meter of the length of the detonating fuse 1. For high energy detonator fuse lines, noise intensity is a serious problem in certain areas. Below the explosive content of 0.1 g per meter length, the reliability of detonation transmission is low if:. the core mixture 2 does not contain a high energy binder or plasticizer. Using such mixtures, i.e. mixtures containing a highly viscous nitrocellulose binder plasticized with trimethylol ethane trinitrate as described in U.S. Patent No. 3,943,017, detonation fuses having a content of less than 0.02 g of a special explosive per meter of detonation fuse length are feasible . It was. It has been found that 0.4 to 2 g of explosive per detonator fuse length tester is particularly suitable for vertical lines and detonating fuses used as stem lines. For explosive cores. low explosive content, as is the case with the detonating fuse · 1 according to the invention, it is very important that the crystalline explosive component consists of "very fine" particles, i.e. particles whose maximum dimension is in the range of approximately 0.1 to 50 μπι. The average largest particle size should typically not be greater than about 20 µm. Larger explosive particles, extreme particle size variations, and foreign matter particles are undesirable as they adversely affect the uniform spread of detonation in the core 2. For use. in core 2, a microporous explosive, the method of manufacture of which is described in U.S. Pat. No. 3,754,061, the disclosure of which is incorporated herein by reference, is particularly suitable.

The content of the explosive in the core 2 depends on the content of the crystalline explosive component in the cemented composition and the diameter of the core. 2. The content of the crystalline explosive component may vary from about. 55 to about 99 weight percent. The low content of the explosive component in the mixture can be compensated for in this range by the larger diameter, core 2. However, at a given explosive content per meter of detonation fuse length 1, the transfer is. detonation is most reliable when the content of the explosive component in the composition is as high as possible, preferably at least about 70% by weight. In the case of an explosive content in the range of about 55 to 90% by weight and a core 2 diameter in the range of about 0.025 cm to 0.152 cm, a content of 0.1 to 2 g explosive per meter of core length 2 can be achieved. 4 g of explosive per meter of length of detonating fuse 1 using a core diameter of approximately 0.069 cm. In addition, the explosive composition comprises 1 to 10% by weight and preferably 2 to 5% by weight of a binder and, if necessary, a plasticizing agent which allows the mixture to be extruded and to ensure the cohesion of the core 2.

The density of the core 2 varies depending on the explosive and binder used and their relative ratio. In addition, iralto specific gravity varies depending on the nature and amount of the other ingredients, if any. The cores 2 made from the compositions described in the aforementioned U.S. Pat. Nos. 2,992,087 and 2,999,743 have a specific gravity usually in the range of about 1.5 g / cm ³ . The specific gravity of this value, compared to the specific gravities of about 1.2 grams / brick attainable using granulated cores, has the advantage of achieving better transmission of the detonation wave and hence a higher detonation velocity at a given core diameter. The cross-section of the core 2 is not critical to the proper functioning of the detonating fuse 1. However, cores 2 with a circular cross-section are preferred, which facilitate the manufacture of conventional detonating fuses 1 with a circular cross-section.

The core 2 is enclosed in a protective sheath 4, which protects the core 2 from abrasion or other damage that might occur during the preparation of blasting operations. Since the main function of the protective sheath 4 is the protection of the core 2, the protective sheath 4 is relatively thin, that is in the range of approximately 0.013 to 0.091 cm. However, in the event that the detonating fuse 1 is to be washed away with particularly adverse stress, a protective sheath 4 of up to 0.318 cm in thickness may be used. With the use of protective shells 4 thinner than about 0.013 cm, it is very difficult to achieve sufficient core protection 2. In the case of the detonation fuse 1 according to the invention, it is unnecessary to use protective shells 4 thicker than 0.318 cm. Furthermore, these thick protective sheaths 4 reduce the flexibility of the detonation fuse 1 and make it difficult to insert the detonation fuse 1 into small diameter boreholes. In view of the ease of application to the core 2 and the sufficient protection of the core 2, the thickness of the protective sheath 4 in the range of approximately 0.051 to 0.127 cm is particularly preferred. When using a preferred explosive content in the core 2 in the range of 0.4 to g per meter of detonation fuse length 1, and with a preferred protective jacket thickness 4 of 0.051 to 0.127 cm, the ratio of core explosive content 2 (g / m) to protective jacket thickness 4 in the range of 3/1 to 39/1.

Within the useful thickness range of the protective sheath 4, it is often desirable to select the thickness of the protective sheath 4 near the upper limit of this range if the explosive content in core 2 per meter of core length 2 is near the lower limit of explosive content. In this way, reliable ignition and transmission of detonation is ensured in these cases.

With a higher explosive content in the core 2, the increased thickness of the protective sheath 4 can provide a reliable transfer of detonation by the nodes and half-loops possibly on the detonation fuses 1.

The protective sheath 4 consists only of one or more plastic layers. That is, all the layers constituting the protective sheath 4 are of plastic and that the protective sheath 4 therefore does not contain any metal layer or woven fabric layer.

The protective sheath 4 is made of plastic, i.e. a deformable substance which is malleable, i.e. it can be extruded at temperatures not substantially exceeding the melting point of the explosive in the core 2. The plastic of the protective sheath 4 is to be extruded at temperatures not exceeding substantially the melting point of the explosive. core 2 by more than about 75 ° C. Thus, it is possible that the protective plastic sheath 4 can be applied to the core 2, for example by extrusion or other conventional deposition method, without undesirable changes in the explosive. The plastic may be resilient and tough after curing. The temperature of the plastic useful in applying the protective sheath 4 to the core 2 may vary depending on the contact time of the core 2 with the applied plastic, the heat exchange rate between the core 2 and the plastic, and the stability of the binder used in the core. on a core 2 containing pentaerythrite tetranitrate, the plastic should not be applied at temperatures exceeding approximately 200 ° C. The plastic may be a thermoset, for example rubber or another elastomer, or a thermoplastic material, for example wax, asphalt, or one or more polyolefins, for example polyethylene or polypropylene, polyesters, for example polyethylene terephthalate; polyamides such as nylon; polyvinyl chloride, ionomer resins and the like, metal salts of copolymers of ethylene and methacrylic acid, and the like. Particularly preferred are protective sheaths 4 of thermoplastic materials, in particular polyethylene, which is available and easy to apply.

Order yourself. The detonation fuse 1 has retained its structure and dimensions even in field conditions, it is advantageous to increase the tensile strength of the detonation fuse 1 and to avoid strangulation of the detonation fuse 1 by using reinforcing elements 3 which prevent damage to the detonation fuse 1 under normal forces. wells. This reinforcement can be carried out with a deposited material

228197 in the plastic layers of the protective sheath 4, for example the fibers or bundles of fibers contained therein, as described in U.S. Pat. No. 2,687,553. The reinforcement of the detonating fuse 1 can also be provided by reinforcements located on the outer periphery of the protective sheath 4. However, it is preferred to reinforce the core 2 with at least one and usually preferably four or more continuous fiber bundles 9, 10 which substantially abut the periphery of the core 2 and extend approximately parallel to the longitudinal axis of the core 2.

The use of fiber bundles 9, 10 positioned between the core 2 and the protective sheath 4 is more advantageous compared to the bundles located in the plastic sheath of the protective sheath, since heat transfer from the plastic to the core 2 is more difficult when applying hot plastic to the core 2. fiber 'as used herein means within the meaning of the Standards of Terminating to Textile Maiterials, ASTM standard D 123-74a, where' fiber 'represents the generic name of continuous thread of textile fibers, or a material occurring as twisted fibers, as together non-twisted deposited fibers as co-deposited fibers that are more or less twisted, single twisted or non-twisted fibers, one or more strips obtained by longitudinal film splitting, for example of natural or synthetic twisted or non-twisted polymers. The individual fiber variants included in this definition are individual fibers, knitted fibers, rope yarn, strand, thread, yarn, etc. The position of the fiber bundles 9, 10 on the core 2 is maintained by the protective plastic sheath 4 surrounding the core 2. and fiber bundles 9, 10 on its periphery. For this purpose, any fiber having such tensile strength can be used to prevent strangulation of the detonation fuse 1 by the forces normally encountered when depositing the detonation fuse 1 in a well. Detonation in detonation fuses 1 should be avoided. A detonation fuse 1 is usually required to have a tensile strength of detonation fuse 1 of at least about 44.5 N. In the event that detonation fuse 1 is to withstand extreme stresses, a minimum is recommended. a tensile strength of about 89 N. The fiber material, the number of fibers and the denier of the fibers are selected so as to provide the required tensile strength of the detonating fuse 1.

Fibers composed of a plurality of individual fibers are particularly preferred, as they tend to decompose around the periphery of the core 2, unlike the individual fibers, which provides thermal insulation when applying the protective sheath 4 of plastic. In addition, the fibers composed of individual fibers make it easier to form a screen roller 14. A smaller number of bundles of thicker fibers may also be used. Fibers thicker than 100 grams of denier are not recommended as they are not uniform in the thickness of the detonating fuse 1. Fibers of natural materials may be used in the bundles, however, it is recommended to use synthetic fibers of polyesters, polyamides and polyacrylic type fibers having an unusual strength. Particularly preferred is the use of nylon, polyethylene terephthalate and aromatic polyamides produced by the condensation of terephthalic acid and phenylenediamine. These fibers having a denier of 40 g or higher have a tensile strength of at least about 44.5. Thus, one fiber bundle 9 of this material can be used in the detonation firing pin 1. However, the use of other fibers contributes to increasing the tensile strength, so it is also desirable. Fibers of smaller thicknesses may also be used, for example below a denier value of 20 g. In a preferred embodiment of the detonating fuse 1, at least four bundles 9, 10 of fibers are approximately equally spaced around the periphery of the core 2 to achieve uniform distribution of the core reinforcements. 9, 10 of the fibers in the net roll 14 just prior to the application of the plastic protective sheath 4 does not present a significant advantage, since the drawing of the net roll 14 and the plastic application results in the spreading of the fibers in the bundles. Therefore, taking into account the circumference of the core 2 and the fiber denier, it is unnecessary to use more than about 12 fiber bundles 9, 10. Typically, the thickness of the fiber layer will not be more than about 0.025 cm.

Especially suitable for reinforcing the core 2 are the woven and multiple fibers described, for example, in U.S. Pat. No. 3,338,764, since these fibers bind firmly to the protective sheath 4 of plastic surrounding them. The bonding between the fibers and the protective sheath 4 of plastic also improves the use of an adhesive agent, for example by applying soft wax ⁽ to the bundles of 9,10 fibers. This adhesive reduces the fiber mobility and the potential adverse effect of this mobility on the core 2. against peeling.

The method and apparatus according to the invention are described below with reference to Figures 2 to 4. Figures 2 and 3 show a first extruder 5 equipped with a piston 6 with an extrusion chamber 29 which is wrapped with a heating coil 7. The extrusion chamber 29 is provided with a suction tube 25 and a sieve 26 which is disposed on one side of the perforated support plate 27. The extrusion chamber 29 contains a mass of a ductile cemented explosive mixture 28 that has already entered the holes in the support plate 27. The other side of the support plate 27 faces the tapered extrusion portion. an extrusion chamber 29 into which the mass of the ductile explosive mixture 28 is pressed by the action of the piston 6 and where a solid rod or core 2 is formed.

In the extrusion die of the first extruder 5, a device 8 is provided for orienting the fiber bundles 9, 18 into a circular arrangement in which the individual bundles

9, 10 of the fibers run approximately parallel. The machine 8 is provided with an axial bore and radial grooves for individual fiber bundles 9, 10 are formed on the surface of the machine 8 which is connected to said axial bore. The transition of the grooved surface of the device 8 into the axial bore is gradual. The machine 8 is positioned such that its groove surface converges with the surface of the first extruder 5 so that the axial bore of the device 8 is coaxial with the core 2 extending from the extrusion die of the first extruder 5, caused by the movement of the piston 6. and 10 of fibers are unwound from respective spools 11, 12 by a tensioning device 13, which bundles 9 and. The 10 fibers pull and tension with a force sufficient to form a moving mesh roller 14 from these fiber bundles 9 and 10. The core 2 extending from the first extruder 5 is enclosed in the screen roller 14 and is moved therewith. The tensioning machine 13 extends through the net cylinder 14 and the core 2 enclosed therein by the extrusion die of the second extruder 15, where a plastic in the form of a protective sheath 4 is applied to the net cylinder 14. The second extruder 15 consists of a cylindrical outer portion 17 and an inner tubular member 16 positioned so that the soft plastic 30 fed by known means - not shown - is through the opening in the outer cylindrical portion 17 between opposite surfaces of the outer cylindrical portion 17 and the inner The tubular member 16 is formed in a tube. The screen roller 14 is moved by an axial opening in the inner tubular element 16. A suction channel 18 passes through the wall of the inner tubular element 16 and opens into an axial opening in the inner tubular element 16. The inner tubular element 16 and the device 8 for orienting the bundles 9, 10 coaxial and spaced apart. Their connection is effected by a connecting tube 19 through which the net cylinder 14 passes in the space between the device 8 and the inner tubular element 16.

The protective sheath 4 provided with the net cylinder 14 comprising the core 2 of the detonation fuse 1 exiting the second extruder 15 passes through a container 20, for example with water, which serves to cure the plastic of the protective sheath 4. The detonation fuse 1 is wound after passing through the tensioning device 13 The winding of the detonation fuse -1 is facilitated by the tension control device 21 through which the detonation fuse 1 passes.

The piston 6 is connected to a sensing device 23 which senses the speed of the piston 6 and sends corresponding signals to a control computer 24, which is coupled to the drive mechanism of the tensioning device 13 and the drive mechanism of the winding drum 22 and controls their speed according to the signal received from sensing device 23.

FIG. 4 shows an alternative embodiment of a second extruder 15 that can be coupled to a first core extruder 5 in a device according to the invention. This particular embodiment of the second extruder 15 comprises means for orienting the fiber bundles 9, 10. to a circular arrangement in which the individual fiber bundles 9, 10 are approximately parallel so that it can be used in the device shown in Fig. 2 without the device 8 for orienting the fiber bundles 9, 10. In this embodiment, the axial bore in the second extruder 15 consists of a cylindrical portion 31 and a conical portion 32. The hollow tapered insert 33 is - in the tapered - portion 32 of the second extruder 15 positioned so that there is only a small gap between the opposing surfaces. The tensioning machine 13 extends through the fiber bundles 9, 10 through openings in the ring 34 for distributing the fiber bundles 9, 10, which are thus drawn along the inner surface of the tapered insert 33. The fiber bundles 9, 10 converge in the tapered portion of the insert 33 so that oriented parallel to each other and passing through the cylindrical portion of the tapered insert 33 then forms a mesh roller 14.

The core 2 entering the cylindrical portion of the tapered insert 33 is enclosed by a mesh roller 14 formed there. The plastic 30 is introduced into the torus space formed between the walls of the tapered insert 33 and the second extruder 15. This torus space is connected to the cylindrical portion 31 of the axial bore by the space between the tapered portion 32 of this axial bore and the apex of the tapered insert 33. 33 is coaxially connected to the cylindrical portion 31 of the axial bore. The screen cylinder 14 formed in the cylindrical portion of the tapered insert 33 and comprising the core 2 is drawn by a stream of plastic 30 which flows through the cylindrical portion 31 of the axial bore that comes from the space between the tapered portion 32 of the axial bore and the apex of the tapered insert 33. The insert 33 is coaxially connected to the cylindrical portion 31 of the axial bore. The screen cylinder 14 formed in the cylindrical portion of the tapered insert 33 and comprising the core 2 is drawn by a stream of plastic 30 that flows through the cylindrical portion 31 of the axial bore that comes from the space between the tapered portion 32 and the apex of the tapered insert. forms a protective sheath 4 on the core 2 surrounded by the screen cylinder 14, so that a detonating fuse 1 is formed.

The preparation of a preferred embodiment of the detonating fuse 1 according to the invention will be further described by the following examples.

Example 1

A. In the extrusion chamber 29 of FIG. 3, there is a mass of a ductile cemented explosive mixture 28 having a weight of 455 g, consisting of a mixture of 76.5% ultra fine pentaerythritol, lithium citrate, 20.2% acatyltributyl citrate, and 3.3. Micropores are dispersed in the ultra fine pentaerythrite tetranitrate in the ultra fine pentaerythrite tetranitrate, and is prepared as described in U.S. Pat.

754 061. The average particle size is less than 15 μΐη, all particles being less than 44 μΐη. The temperature of the extrusion chamber 29 is maintained at 63 ° C by the heating winding 7, which aids the extrusion of the explosive mixture. After placing the explosive charge into the extrusion chamber 29, the piston 6 is sealed to the extrusion chamber 29. A suction tube 25 generates a vacuum of —98.650 Pa, which is maintained for 1 minute. This is done to prevent air from becoming trapped in the explosive mixture 28, which could cause discontinuity of the extruded core 2, which would adversely affect its ability to transmit detonation. The piston 6 is then moved further until the explosive mixture 28 is compressed. The piston 6 is only moved so far that the explosive mass is not yet displaced.

The fiber bundles 9, 10 and four other fiber bundles (not shown) are threaded into radial grooves in the device 8 and passed through the axial bore in the device 8 and the inner tubular element 16, which is accomplished by switching on the drive of the tensioning device 13. Each of the six fiber bundles consists of a 50 g denier of polyethylene terephthalate yarn. The tension of each of these bundles 9, 10 and others is maintained by the tension control device 21 at a value of 1.1 N. The plastic supply means 30. This plastic compound 30 is composed of a low density polyethylene having a temperature of 150 ° C. The container 20 consists of two parts. In the first compartment through which the detonating fuse 1 passes, there is water at 81 ° C, in the second compartment there is water at 21 ° C. This two-stage cooling contributes to the even cooling of the protective sheath 4 of plastic, and promotes a closer fit of the protective sheath 4 on the sieve roller 14. The diameter of the portion of the first extruder 5 where the core 2 is formed is 0.076 cm. The gap between the opposing surfaces of the outer cylindrical portion 17 and the inner and backsheet element 16 of the first extruder 15 is such that a polyethylene protective sheath of 0.089 cm thickness is formed.

After actuating the tensioning device 13, the tension control device 21, the winding drum 22 and the container 20 are in operation, the piston 6 is moved at a speed of 1.270 cm per minute. The explosive mixture 28 is forced through a sieve 28 to trap and discard particles larger than 25 μη. The explosive mixture 28 further passes through the holes in the support plate 27 and is formed into a solid core 2 with a diameter of 0.076 cm. The core 2 exits the first extruder 5 at a speed of 75 m / min. and the speed of the net cylinder 14 moved by the tensioning device 13 and wound onto the winding drum 22 is controlled by signals received from the control computer 24 as a function of the exit speed of the core 2. The suction channel 18 generates a vacuum to assist adhesion of the protective sheath 4 to the net a cylinder 14 comprising a core 2 as it passes through the inner tubular element 16. In the inner tubular element. 16, a vacuum of 20,000 Pa is maintained.

The detonating fuse 1 wound on the winding drum 22 has an outer diameter of 0.254 cm, a core diameter of 2.076 cm. and a polyethylene protective sheath 4 having a thickness of 0.089 cm. The content of pentaerythrite ietraimate in the core 2 is 0.533 grams / m in length, the ratio of the content of pentaerythrite tetranitrate in meters of length to centimeter of the thickness of the protective sheath 4 is 6/1 and the specific gravity of the core 2 is 1.5 g / cm ³ . The fibers of the fiber bundles 9, 10 and others substantially completely surround the core 2 as shown in Fig. 1. The detonating fuse 1 is flexible and light, its tensile strength is 440 N.

Detonating fuse 1 ignited by detonator No. 6, whose end coaxially abuts one end of detonating fuse 1, detonates at a speed of 6900 m / sec. Detonating fuses 1 tangled to each other along their length do not ignite each other. Detonation in the continuous section of detonation fuse 1 also spreads through knots of different kinds. The detonation fuses 1 can also hardly be ignited if the detonation fuse 1 is not aligned with the detonator.

B. The same detonating fuse 1 is produced as in the procedure described in Part A., except that the fiber bundle orientation device 8 and 10 of FIG. 3 is replaced by a second extruder 15 of FIG. For tensioning, the cylindrical portion of the tapered insert 33 extends through the four fiber bundles 9, 10 with a force that allows the fiber bundles 9, 10 to be grouped in a moving mesh roller 14 with approximately parallel fiber bundles 9, 10. 14 containing the core 2 is drawn through the polyethylene stream through the cylindrical portion 31 of the axial bore, whereby a soft polyethylene protective sheath is applied to the screen roller 14. As in the case of Part A., there is no appreciable reduction in the diameter of the core 2 when the protective sheath 4 is applied to the core 2.

By appropriate selection of die size and extrusion speeds, detonating fuses can be manufactured by the methods described. 1 with different core diameters 2, different protective sheath thicknesses 4 and different number of fiber bundles 9, 19.

The use of the low energy detonating fuse 1 according to the invention and the influence of various parameters such as the explosive content in the core 2, the core diameter 3, the thickness of the protective sheath 4 and the composition of this protective sheath 4 and

Example 2

In a pressed aluminum cup having a wall thickness of 0.08 mm, 0.26 g of the very fine pentaerythrite tetranitrate described in Example 1 is placed. The end of the cup is adjacent to the side of the 3 meter long detonation fuse 1 described in Example 1A. 1, in this case, the core 2 has a diameter of 0.120 cm and the content of penitaeiryithrite teitrainitrate in the core 2 is 1.49 g / m in length. This detonation fuse 1 serves as a stem guide. One 1.5 meter long end of the detonation fuse 1 described in Example 1A is inserted into an aluminum shell (damper) that contacts the detonation fuse 1. The other end of the detonation fuse 1 abuts laterally on an impact-sensitive element, such as a shock delay detonator. The detonation is transmitted from the stem line to the silencer, from the silencer to the vertical line and by the vertical line to the delayed impact detonator.

These results were achieved with a stem line made up of detonating firing pin 1 containing 2.13 g and 0.938 g explosives per meter of length, corresponding to a core diameter of 2 0.152 cm and 0.102 cm. The same results were also obtained for vertical ducts made up of 0.638 g and 0.469 g explosives per meter of length, corresponding to cores of 2.084 cm and 0.07 cm, respectively.

Example 3

The following tests describe the types of adverse stresses, such as kinking, tensile and abrasion, which the detonating fuse 1 of the invention can successfully withstand.

A. One end of the 18 m long vertical conduit formed by the detonating firing pin 1 described in Example 1A is laterally applied to the delay detonator. This detonator is housed in a 0.9 kg cartridge (a tube of resilient material with press-fit ends) having a diameter of 5 cm and a length of 41 cm and containing a non-explosive mixture simulating a water gel explosive. Mutual position of detonator and detonation fuse 1 is in the cartridge secured by two half loops. The cartridge is lowered into a 15 m deep model borehole, which is done by various insertion methods that may occur in field conditions. The model (simulated) borehole consists of the inside of a vertical steel tube with a diameter of 13 cm. The other end of the 0.53 g explosive per meter length of vertical line is attached to the silencer and to the 1.5 g explosive per meter length line described in Example 2. After the tube has been filled as described, the stem line is ignited as described in Example 2. The entire vertical conduit detonates and the impact delay detonator detonates after the nominal time has elapsed, although the combination of the vertical conduit, detonator and cartridge has previously been subjected to the following load tests:

I. The cartridge is allowed to fall freely over the entire length of the vertical guide.

II. The free-fall of the cartridge is halted after every 4.6 mieitrú.

III. The detonating fuse 1 rubs against the coarse edge of the steel pipe when the tube is lowered.

IV. Combination of stresses from points II. а III.

In the tests of points I, II, III and IV, a 3.2 kg sand bag is repeatedly lowered and pulled along the detonator and cartridge casing in the tube. Lowering and pulling is repeated a total of 5X, the sand bag in its fall scuffs detonation fighters i.

B. A knot is tightened to the detonation fuses 1 described in Example 1A and a 3.2 kg mass is suspended at the end of the detonation fuse 1. The weight is lowered into the 15 m long tube described in Part A of the example, whereby the free fall of the weight is stopped 5X to achieve a better knot tightening. It gradually detonated 5 detonation fuses 1 modified in this way without interrupting the detonation in the nodes.

Example 4

The use of the detonation fuses 1 described in Examples 1 and 2 to transmit the detonation to the lower charge of the blast column in the wells is as follows:

Each of the wells having a depth of 7.6 m and a diameter of 7.6 cm is provided with three mutually covering cartridges of 5 x 41 cm, consisting of a water gel explosive described in U.S. Pat. No. 3,431,155 embedded in a polyechylene terephthalate film. The boreholes are six and are 2.4 m apart. In the lower case of each bore there is an impact delay detonator connected to the detonation fuse 1 (vertical guide) described in Example IB as described in Example 2. The remaining ends of each vertical guide are connected to by the stem conduit described in Example 2 (except that it has four bundles of 9, 10 fibers), as described in Example 2. No plugs are used. The stem line detonation induces a gradual detonation of the charges in the boreholes, always starting with the lower charge. The detonation procedure is determined by the timing of the individual detonators. Column violation noticeable.

Examples 5 - 10

Detonating fuses 1 are manufactured as described in Example 1. The explosive core 2 composition has the following composition: 76.1% by weight of very fine pentaerythrite teitramate, 20.3% by weight of acetyl-tributyl citrate and 3.6% by weight of nitrocellulose. The four fiber bundles 9, 10 described in Example 1 are used. The same material composition of the protective sheath 4 is used as in Example 1. The core 2 is extruded at different diameters and protective sheaths 4 of different thicknesses are applied. The detonating fuse 1 ignited as described in Example 1 behaves as follows:

example diameter content detonation speed (m / sec) detonation fuses on external core PETN diameter in cm (cm) (g / m) 0,178 0,203 0.229 0.254 0.318 5 0,033a) 0,107 6600 6 0.051 0.213 6700 6600 6600 7 0,076 0.533 6800 6800 6600 6700 6700 8 0,102 0,938 6800 6800 6800 7200 9 0,127 1.49 7000 10 0.152 2.13 7000

The abbreviation PETN stands for pentaerythrite tetranitrate

a) This detonation fuse 1 was ignited and transmitted detonation in 50% of the experiments performed; all other detonating fuses. detonated reliably.

These examples show that the detonation rate of the tested detonation fuses 1 is in the range of 6900 m per second + 5 ^; % independently of the pentaerythrite tetranitrate content per meter of length and the thickness of the protective sheath 4 of plastic. However, at this core composition 2 and a protective sheath thickness 4 of 0.112 centimeter, the reliability of detonation at the smallest pentaerythrit tetranitrate content and the smallest core diameter 2 is somewhat reduced.

Examples 11-14

The detonation fuse 1 described in Examples 5 to 10 is tested for three different explosive contents in core 2 and core diameters to determine the reliability of ignition and transmission of detonation at minimum protective sheath thicknesses 4.

Example PETN content (g / IU average number of missed launches from 10 experiments at core thickness in cm (cm) 0 0,025 0,038 0,064

11 0,107 0,033 0 10 12 0.213 0.051 4 10 13 0.533 0,076 8 10 14 1.49 0,127 10

These examples show that as the core diameter 2 and the pentaerythrite tetranitrate content per meter of length increase, the protective plastic sheath 4 has a negative effect on the detonation fuse 1's ability to ignite and transfer detonation.

Example 15

The detonation fuse 1 described in Examples 5 to 10 with a core diameter 2 of 0.076 cm is manufactured with various protective sheath materials 4 and protective sheath thickness 4. All samples (at least 46 m long) of the detonation fuse 1 with protective sheath thickness 4 0.051 cm, 0.071 cm and 0.084 cm of low density polyethylene, high density polyethylene and a metal salt of an ethylene-methacrylic acid copolymer (ion exchange resin) reliably detonated at a rate of about 7200 m / sec. with both four and eight fiber bundles 9, 10. In the application of high density polyethylene, the extrusion die temperature is 175 ° C, while in the ionomer resin application the temperature is 135 ° C.

The minimum tensile strength of all samples made with four bundles 9, 10 fibers is 315 N. The minimum tensile strength of all samples made with eight bundles 9, 10 fibers is 630 N. All samples detonated independently of the thickness of the protective sheath material 4 and its type as follows: 2.7 kg of mass is suspended at one end of the detonating fuse 1. The detonation fuse 1 is pulled over the edge of the concrete block by this weight, whereupon the detonation fuse 1 is pulled back to its initial position. This procedure is repeated five times.

24

Examples 16-19 of the fuse 1 described in Examples 5 to 10 when nodes are formed thereon, which may

The effect of explosive content in core 2 and thickness occurring in field conditions, describes the protective shell 4 on the detonation behavior of the following table:

example PETN content (g / m) core diameter (cm) sheath thickness (cm) conceived of successful detonation transmissions half-loops node 16 0.533 0,076 0,089 15 ^(a ) 5 ^) 17 0.638 0,084 0,086 15 ^(a ) 5 ^b ) 16 0,723 0,089 0,084 13 ^a ) 2 ^(b ) 19 Dec 0,853 0,102 0.109 14 ^a ] 4b)

The abbreviation PETN stands for pentaerythrite tetra nitrate

a) from 15 attempts

b) knot tightened by 44.5 N, out of 5 attempts

These examples show that the detonation fuses 1 carry detonation through the nodes and do not interrupt the transmission of detonation in the nodes due to excess explosive energy. It also follows from the example that increasing the thickness of the protective sheath 4 will provide detonation transmission through the nodes as the explosive content of the core 2 increases.

PET eg fibers number of aramid yarn bundles

Examples 20 - 24

The detonating fuse 1 described in Examples 5 to 10 with a core diameter of 0.076 cm is made with a different number of polyethylene terephthalate bundles. fibers and aramid yarn made from a condensation polymer of terephthalic acid and phenylenediamine (fiber denier 50 g). The influence of these structures on the strength of the detonation fuse 1 and the ability of the detonation fuse 1 to transmit detonation through the nodes is described in the following table:

fort det. number of detonations. transmitted fuses through nodes in a thrust (N) half-loop node

20 May 2 195 4a) 0, 0, 0, 0 ^b ) 21 4 360 (10a) 0, 0, 0, 0 ^b ) 22nd 8 665 (10a) 3, 3, 3, 0b) 23 2 470 9 ^a ) 1, 0, 0b) 24 4 880 (10a) 3, 3, 3, 3b)

PET stands for polyethylene terephthalate

a) from 10 attempts

b) knots tightened with 44 N, 89 N, 133 N and 178 N, out of 3 attempts for each force value

The example shows that the tensile strength of the detonating fuse 1 at a given number of fiber bundles 9, 10 of the same denier depends on the tensile strength of the fibers. In this case, the aramid yarn guarantees a higher tensile strength of the detonating fuse 1 with less bundles than polyester. The example also shows that multiple bundles of certain fibers or thicker fibers increase the ability of the detonation fuse 1 to transmit detonation through more tightened nodes.

Example 25

A continuous solid core 2 of a cemented explosive mixture consisting of 75% by weight of very fine pentaerythrite tetranitrate and 25% by weight of a binder represented by a copolymer of butadiene, acrylonitrile and methacrylic acid (described in U.S. Pat. condensation polymer of terephthalic acid and phenyldiamine. The core 2 and the reinforcement bundle are co-threaded through an extrusion die which applies a 0.064 cm thick low density polyethylene protective sleeve 4 thereto. The resulting detonation fuse 1 having a pentaerythrite tetranitrate content of 1.49 grams / m in length, deionizes at a rate of approximately 7000 rn / sec if ignited by the method described in Example 1. The tensile strength of the deformation fuse 1 is about 335 N.

Example 1 a d 2 6

The malleable explosive mixture described in Example 1 (except that the content of ultra fine pentaerythrite tetranitrate is 76%, 20% acetyl tributyl citrate and 4% nitrocellulose) is extruded to form dest 1.2 km long cores 2, of which five have a diameter of 0.076 cm (0.533 g / m pentaerythrit tetranite

228167 (1.49 g / m &lt; 2 &gt; pentaerythrite tetranitrate). The extruded cores 2 are threaded into a low density polyethylene tube having an inner diameter of 0.152 cm and an outer diameter of 0.20 cm. The ratios of the core explosive content to the wall thickness of the detonating fuses are 18/1 and 50/1 (explosive content in g / m, jacket thickness in cm). All these detonating fuses 1 have a tensile strength of about 44 N.

Detonation fuses 1 are ignited by detonator No. 6, the end of which coaxially abuts one of the ends of detonation fuse 1. All of these detonation fuses 1 detonate without interruption while all protective sheath material is digested. The average detonation speed of all ten detonation fuses is · 7300 m / sec.

In the process according to the invention, after the core has been formed, there is no substantial change in its diameter. This produces a high-density core which does not need to be reduced in diameter, as is the case, for example, in the manufacture of detonating fuses with granular explosive cores. Eliminating core diameter variations during manufacture simplifies production control with a view to achieving the desired final explosive content in the core and prevents the fiber bundles surrounding the core from entering the core.

In detonating fuses with small diameter cores and low explosive content per meter of length, the presence of foreign matter particles, such as sand, metal and the like, may be an obstacle to detonation if the particles are reasonably large. An important part of the process according to the invention is therefore to avoid the presence of such particles in the core, which is achieved by a method of preparing a mixture using a sieve on a core extruder. For cores with a diameter of about 0.076 cm or greater, there should be no particles larger than about 33% of the core diameter in the core. For small diameter cores, particles larger than about 0.013 cm should not be present in the core.

In the manner in which the fiber bundles and the explosive core enter the extruder forming the plastic sheath separately, the sieve roller to be manufactured usually surrounds the core and the sheath is then formed on the core provided with the sieve roller. However, the formation of the mesh roller, the introduction of the core into the jacket and the application of the jacket can be carried out substantially separately. Also, two extruders of the device, i.e. the core extruder and the sheath forming machine, may be separate or may be arranged together in a single combined extruder.

Claims (21)

SUBJECT 1. A low-energy detonating fuse, consisting of a continuous solid core of a detonation explosive, a reinforcement element therefor and a protective sheath covering the core and reinforcement elements, characterized in that the detonation explosive is a malleable explosive mixture containing at least 55% by weight of crystalline explosive component. detonator sensitive, selected from the group consisting of organic polynitrates and polynitramines mixed with a binder, the largest dimension? the particles of crystalline explosive component in the binder range from 0.1 to 50 μηι and the core (2) contains 0.1 to 2 g of crystalline explosive component per meter of length, the reinforcing elements (3) being arranged outside the core (2) and the protective sheath ( (4) consisting of at least one layer consisting of a plastic material which is malleable at a temperature not exceeding the melting point of the crystalline explosive component by more than 75 ° C. Detonating fuse according to claim 1, characterized in that the reinforcing elements (3) of the core (2) consist of at least one continuous fiber bundle (9, 10) arranged on the periphery of the core (2) and running approximately parallel to the longitudinal axis of the core (2). 2), wherein the fiber bundle (9, 10) has a strength eliminating the strangulation of the core (2) due to forces occurring during insertion into the boreholes to an unacceptable failure rate. Detonating fuse according to claim 2, characterized in that the core reinforcing elements (3) OF THE INVENTION (2) consists of at least four fiber bundles (9, 10) distributed uniformly over and adjacent to the periphery of the core (2), the fiber bundles (9, 10) having a tensile strength such that together with the core (2) ) have a tensile strength of at least 44 N and are surrounded by a protective sheath (4) together with the core (2). 4. Detonation. fuse according to claim 3, characterized in that the fiber is multiple and its veins are distributed around the core (2). Detonating fuse according to claim 1, characterized in that the crystalline explosive component of the core (2) is selected from the group consisting of pentaerythritol tetranitrate and cyclotrimethylenetinitramine. 6. Detonating fuse according to claim 5, characterized in that the explosive mixture contains at least 70% by weight of pentaerythrite tetranitrate, the core (2) contains at least 0.4 grams of pentaerythritite tetranitrate per meter of length and the protective sheath (4) is of thermoplastic material. 7. The detonating fuse of claim 1, wherein the binder is plasticized non-cellulose. Detonating fuse according to claim 6, characterized in that the thermoplastic material of the protective sheath (4) is a polyolefin malleable at a temperature of up to 200 ° C. 9. Detonating fuse according to claim 8, characterized in that the thermoplastic material of the protective sheath (4) is polyethylene and the wall thickness of the protective sheath (4) is in the range 0.051-0.127 cm. Detonating fuse according to claim 6, characterized in that the wall thickness of the protective sheath (4) ranges from 0.013 to 0.318 cm. 11. A method for producing a detonating fuse by shaping a continuous core from a detonating explosive and applying a protective sheath to the core, wherein the core is formed from a detonator-sensitive crystalline explosive component with a binder and forming a moving mesh roll with approximately parallel longitudinal bundles, between which a core is introduced without changing the diameter, so carried by this net roller, onto which a layer of soft plastic is applied, which subsequently cures. 12. The method of claim 11, wherein the core is extruded into the mesh roller and the plastic is extruded around the core mesh roller. Method according to claim 11, characterized in that the core net cylinder is surrounded by a plastic tube. Method according to claim 11, characterized in that the core net cylinder is guided by a stream of plastic from which a protective sheath is formed around the core net cylinder. 15. The method of claim 11, wherein the detonation explosive core is vacuum formed. 16. The method of claim 11, wherein particles larger than 25% of the core diameter are removed from the detonation explosive. Apparatus for the production of a detonating fuse, comprising a device for producing a continuous solid core from a detonation explosive and a device for applying a protective sheath to the core, characterized in that it comprises a first extruder (5) for shaping the mass of a malleable explosive mixture (28) in a continuous solid core (2), from the device (8) for orienting the fiber bundles (9, 10) to a circular arrangement in which the fiber bundles (9, 10) are approximately parallel to each other, further from the device (13) for tensioning approximately parallel fiber bundles (9, 10) by pulling sufficient to form the fiber bundles (9, 10) into a moving screen roller (14), the fiber bundle (9, 10) being oriented (8) relative to the first extruder machine (5) arranged so that the net roller (14) surrounds and entrains the core (2) protruding from the first extruder ( 5), further from a second extruder (15) for applying a soft plastic in the form of a sheath (4) to a substrate (2, 14) passing through said second extruder (15), the second extruder (15) and the device (8) for orienting the fiber bundles (9, 10) are arranged such that the core (2) provided with a mesh roller (14) passing through the second extruder (15) is the substrate for applying the sheath (4), avoiding previous, continuous or subsequent diameter reduction the core (2), and finally from the container (20) for curing the plastic of the sheath (4) of the supplied core (2) provided with a mesh roller (14) and the sheath (4). Apparatus according to claim 17, characterized in that the first extruder (5) is provided with an extrusion chamber (29) provided with a suction tube (25) for applying a vacuum. Apparatus according to claim 18, characterized in that a means (26, 27) for separating particles having a dimension greater than 25% of the diameter of the core (2) from the core (2) is provided in the extrusion chamber (29). Apparatus according to claim 17, characterized in that the first extruder (5) is provided with a plunger extruder comprising a heated extrusion chamber (29). Apparatus according to claim 17, characterized in that the first extruder (5) with a device (13) for tensioning the fiber bundles (9, 10) is connected to a sensor (23) for operating the first extruder (5) for controlling the device. (13) for tensioning the fiber bundles (9, 10).