WO2009025573A1

WO2009025573A1 - Hollow charge

Info

Publication number: WO2009025573A1
Application number: PCT/RU2007/000452
Authority: WO
Inventors: Sergey Ivanovich Zonenko
Original assignee: Germanov, Evgeny Pavlovich
Priority date: 2007-08-21
Filing date: 2007-08-21
Publication date: 2009-02-26
Also published as: CN101836069A; WO2009025573A8

Abstract

The inventive hollow charge comprises a body (1) in the form of an open shell, explosive material (2) which is placed therein and is provided with a hollow cavity arranged in the open section of the body (1), a triggering device (3) arranged in the closed section of the body (1) and a lining (4) which is adjacent to the hollow cavity and has a relief formed by irregularities (5) dependent on the undulations of the shape and the thickness thereof. One or more pads (6) which in part or totally separate the explosive material (2) from the charge body (1) can be placed layer-by-layer without gap on the inner surface of the body (1). A lining (4)is designed in the form of a solid body which is adjacent to the hollow cavity and is limited by two surfaces, the thickness of which is less than the other sizes thereof, in general, the thickness of lining being variable. The corrugated lining can be considered as a special case of a relief lining when the reliefs of the two lining surfaces are in agreement with each other. The optimal distribution of distances between the relief strips is determined the material of the lining (4), the thickness thereof at different sections and by a pressure generated by explosion of the explosive material (2). The best piecing results are obtained when the middle wavy line of the lining (4) sections along the generating lines of the relief have a wavelengths within a range of (0,3÷0,7)hlin.L/H, and a bent having a length of (0,5÷1,5)hlin.L/H is formed on the side of the open section of the body, where hlin. is the mean thickness of the lining (4) at the wavelength of interest, L is the wavelength of the initial disturbances of a plate, with a thickness H, increasing most rapidly, and the L/H ratio between a specific material and the used explosive material is determined by statistically treating the results of corresponding experiments. Said invention makes it possible to increase the performance characteristics and the piercing capacity of the charge, to simultaneously reduce the production cost and provide the stability of the results of use thereof.

Description

Cumulative charge Field of the invention The invention relates to the field of devices for explosive impact on condensed matter and can be used for secondary opening of formations during oil and gas production, for creating holes and channels in solid materials, for explosive cutting of metals and other durable materials, for drilling holes when tunneling in hard rocks, for crushing oversized materials, for the destruction of material objects, during emergency recovery, geophysical, seismic, construction and other works.

BACKGROUND OF THE INVENTION Most of the known cumulative explosive devices are based on explosive compression of a conical cladding (or spherical, parabolic, “bell-shaped”, “tulip-shaped”, etc.) close to it. The so-called "impact nuclei" and all kinds of "projectile-forming charges" differ little in principle from traditional charges. All known cumulative charges have the same drawbacks: low target exposure compared to the energy stored in the explosive used (even after subtracting all the heat and other losses), and the large spread in the results of the charges is instability. When designing cumulative charges, most attention is paid to the shape and distribution of the thickness of the lining. Due to this, they seek to increase the efficiency of charges and expand the range of parameters of their work. Bilayer and multilayer claddings are also used, which complicate the manufacture and increase the cost of cumulative charges without significantly increasing their breakdown ability. The most common because of their effectiveness, accessibility and knowledge are copper cladding. In their manufacture, special attention is paid to the isotropy of the metal, surface cleanliness, manufacturing accuracy and other technological factors.

The possibility of increasing the efficiency of cumulative charges is associated with the use of more expensive metals and their alloys: tungsten, depleted uranium, etc. Complex processing technologies are also proposed that affect the structure of metals and the resulting alloys: crystal lattice, granularity, etc.

The use of these metals, alloys and their processing technologies does not eliminate the problem of pest formation under the action of traditional cumulative charges, which is of great importance in the perforation of oil and gas wells. To solve this problem, facings made of powder materials are used, the manufacture of which is also quite time-consuming. Moreover, charges with powder coatings are less stable in operation than charges with metal coatings.

It is more efficient to use liners with cumulative initial charges in the form of inhomogeneities of shape, thickness, and other parameters.

Known is a cumulative charge containing a body in the form of an open shell, an explosive placed inside it, an initiating device located in the closed part of the body, and a throwing element located in the open part made in the form of a round plate, and the area adjacent to the edge of the plate is made heterogeneous in the circumferential direction and bent forward by 5-20 ° relative to the plane of the central part (RU Ns 2253830, 2005).

Setting initial disturbances of the propelling element in the form of a wavy edge, variable thickness, variable density, etc. - helps to reduce the growth of chaotic disturbances during the explosion, but does not completely eliminate them. The disadvantages of this charge are the loss of the explosive energy of the charge as a result of the inevitable short-wave spontaneous instability, acceleration instability, and the absence of an explicit perforating rod capable of forming a channel in the target with a shape quite close to cylindrical.

Known cumulative charge containing a housing in the form of an open shell, an explosive placed inside it, an initiation device located in an opening in the closed part of the housing, and a lining, which is a shell with a density greater than 7 r / cm ³ , on one or two surfaces of which is made relief of triangular or hexagonal convex elements, and the distances between the centers of adjacent convex elements are at least 4 average thicknesses of the cladding, and the height of the relief elements does not exceed the average thickness o blitzing (RU Ns 2277167, 2006).

The creation of this relief leads in the process of explosive throwing of the cladding to the formation of ordered three-wave structures and a more effective cumulative effect on the obstacle; but it is not possible to minimize the dissipation of energy. The disadvantages of this charge are the relatively low efficiency of the use of explosive energy.

Known closest to the claimed cumulative charge, comprising a housing in the form of an open shell, an explosive placed inside it with a cumulative recess located in the open part of the body, an initiating device located in the closed part of the body, and a lining adjacent to the cumulative recess facing the explosive the surface material of which there is a relief made of protrusions or recesses in the form of strips forming polygons (RU NQ 2303232, publ. July 20, 2007, prototype). In the particular case of the indicated relief, it can have generatrix lines, and along them sections with wavy center lines and sections with center lines without waves, while the wavy center lines can be smooth or stepped (see Fig. 2-4 of this description). Similarly, the center lines can be formed in planes perpendicular to the axis of the cladding, if these strips of relief are directed along the parallels of the cladding.

The lining performed with the relief proposed in this information source plays the role of a kind of spatial modulator in the path of the high-pressure wave front that occurs at the time of the explosion. As a result, standing waves are formed on the cladding, which reduce spontaneous vibrations, reduce energy dissipation and, ultimately, increase the breakdown ability of a charge. The disadvantage of this charge is that during its operation it is only possible to reduce to a small extent the energy dissipation associated with fluctuations and an increase in the initial perturbations, and, therefore, to slightly increase the efficiency, accuracy and stability of explosive throwing, at the same time it is not possible to provide the formation of a homogeneous perforating rod of the optimal (bullet-shaped) configuration. Disclosure of invention

An object of the invention is the creation of an effective design of the cumulative charge, as well as the expansion of the arsenal of cumulative charges.

The technical result that provides a solution to the problem is to increase the efficiency and breakdown ability of the charge by eliminating energy losses associated with fluctuations and an increase in initial disturbances, as well as improving the accuracy and stability of explosive throwing of the cladding with the formation of a uniform perforating rod of an optimal bullet configuration that can create a channel with a shape close to cylindrical in the target, achieved due to the presence of specially created optimized heterogeneities (relief) on corresponding cladding surfaces and the presence of bumps on the surface of the explosive from the side of the body, formed, for example, by means of a gasket. At the same time, manufacturing costs are reduced and the stability of the results of use is ensured.

The essence of the invention lies in the fact that the cumulative charge comprises a body in the form of an open shell, an explosive placed inside it with a cumulative recess located in the open part of the body, an initiation device located in the closed part of the body, and a relief cladding adjacent to the cumulative recess so that the middle lines of the cladding sections along the generatrix lines of the relief, as well as the middle lines of the cladding sections by planes perpendicular to the axis of the cladding, are about wavy lines, or lines without waves, while the wavy middle lines can be smooth or stepped, and the relief is made either on the facing surface facing the open part of the body, or on both surfaces of the facing.

The cladding can be made corrugated when the reliefs on both surfaces of the cladding coincide, while the protrusion of the relief on the opposite surface of the cladding corresponds to the deepening of the relief on one surface.

In preferred embodiments, the wavy lines mean facing sections forming relief along lines having wavelengths in the range (0,3 ÷ 0,7) h p.L _Ob / H, where: h _SSB. - the average thickness of the lining at the considered wavelength,

L is the wavelength of the fastest growing initial perturbations of the plate with a thickness H taken in the range of (0.5 ÷ 1, 5) / 7 _Obl ., Made of the same material as the cladding material, empirically determined from the greatest depth of the craters in targets obtained by throwing a plate on a target located on a distance of 20H ÷ 50H from the plate, using explosives used in a cumulative charge. The initial perturbations of the plate are created due to the undulation of the form or due to the relief; in the latter case, the relief is performed on the surface of the plate adjacent to the explosive block.

To improve the charge at the edge of the cladding from the side of the open part of the housing along the cladding, a bend with a length

(0.5 ⁺ 1, 5) LoL / H.

In special cases of implementation, the lining is performed in the form of a lateral surface of a truncated cone with a relief in the form of recesses and protrusions, the distances between the midpoints of adjacent recesses and the distances between the midpoints of adjacent protrusions counted along the generatrices of the cone are in the range (0.3-10.7) Λ _O bl./- In the simplest case, the facing is made from the workpiece in the form of a flat annular sector by folding, and the relief on the workpiece is by stamping on a flat ring matrix.

The lining can be made of a sheet of copper or its alloys with a thickness of 0.4 ÷ 4.0 mm, and the ratio LIH increases with increasing hardness of the material of the sheet and decreases with its decrease within 11 ÷ 15.

In order to break the front of the detonation wave incident on the charge body, the surface of the explosive from the body side is made with protruding or recessed elements. In the particular case, BB can fill in the bumps made on the inner surface of the housing.

The cumulative charge can be equipped with one or more gaskets located between the explosive and the casing, partially or completely separating the explosive and the casing of the charge, while the gasket adjacent to the inner side of the casing is made of a material softer than the casing material. The gasket adjacent to the explosive can be made with holes or recesses, and explosive fill these holes or recesses in the gasket. In optimal embodiments, the size of the perforation holes or recesses in the gasket is (0.5 ÷ 2) d _cr ., And the distance between them is (1 ÷ 5) d _cr ., Where c / _cr. - the critical diameter of the detonation used in the charge BB.

List of drawings

In the drawing of FIG. 1, 2 shows a structural diagram of a cumulative charge: in FIG. 1 is a general view, in FIG. 2 - charge cross section. In FIG. 3-10 illustrate some possible patterns for the relief of the cladding. For clarity, reliefs are shown on the outer surface of the conical lining adjacent after being charged to the explosive; a similar relief is made on the inner surface; note that the relief may not be present on the outer surface. In FIG. 11, 12 show the results of experiments to determine the fastest growing initial perturbations of a plate thrown by an explosion. In FIG. 13-15 are examples of cladding sections along the generatrix lines of the relief and the corresponding middle lines, which are highlighted in white. In FIG. 16 is a scan view of a conical cladding with a 60 ° opening angle made of a copper sheet. In FIG. 17 is a three-dimensional image of a copper conical lining with a relief on the inner surface and a bend near the base of the cone, and in FIG. 18 is a three-dimensional image of a similar lead conical lining; the generatrix lines of the relief of the cladding shown coincide with the generatrix of the cone and are straight. In FIG. 19-22 show embodiments of the cumulative charge, of which: in FIG. 19 - without laying with an uneven surface of the explosive from the side of the body; in FIG. 20 - without gasket, the inner surface of the body has protruding or recessed elements, the explosive fills these irregularities; in FIG. 21 - with a single layer soft gasket and uneven BB surface; in FIG. 22 - with single layer soft perforated gasket, BB fills the perforations. In FIG. 23,24 depicts flat reamers of gaskets with different perforations.

The best options for implementing the invention

The cumulative charge (Fig. 1, 2) contains the housing 1 in the form of an open outer shell, an explosive (BB) 2 placed inside it with a cumulative recess (not indicated) located in the open part of the housing 1, the initiation device 3 located in the closed part case 1, and facing 4 adjacent to the cumulative recess, having a relief formed by irregularities 5 associated with the waviness of its shape and thickness. On the inner side of the housing 1, one or more gaskets 6 can be layered in layers without a gap, partially or completely separating BB 2 and the charge housing 1.

Cladding 4 hereinafter means a solid adjacent to the cumulative recess, bounded by two surfaces, having a small thickness compared to other dimensions, while the thickness of the cladding is generally variable. For example, the implementation of the relief on one or two surfaces of the cladding can lead to a change in its thickness. Corrugated cladding can be considered as a special case of embossed, when the reliefs on both surfaces coincide, while the relief protrusion on one surface of the cladding corresponds to the protrusion of the relief on its opposite side (Fig. 15).

To describe the relief of cladding 4, the concept of generatrix lines of relief is used, which is largely similar to the concept of generators of a surface of revolution.

The surface of rotation is formed by the rotation of the line around a fixed line, called the axis of the surface of rotation. This line is called the generatrix, as well as all the lines obtained by its rotation around the specified axis. The forming surface of the rotation can be spatial or flat curve (lying in some plane), for a conical surface - a straight line.

The forming lines of the relief are the lines on the surface of the cladding along which the relief is formed. They can be spatial or flat. In this case, the generatrix of the relief when turning relative to the axis of the lining can change their shape, creating waves in the circumferential direction; for surfaces of revolution, such circumferential lines are called parallels, and they have no shape waves. It is necessary to distinguish between forming surfaces and forming relief lines. For the same surface of revolution (and, accordingly, its generators), it is possible to form different generatrix lines of the relief, in the general case, not flat. For example, in FIG. 3 and 4, the shape of the cladding is conical, the cone generators are straight (not shown), and the relief generators are helical lines directed in different directions.

In a particular case, the forming relief lines are the lines of intersection of the surface of the cladding with the planes passing through the axis of the cladding; for surfaces of revolution such lines are called meridians.

The set of all meridians or parallels is a continuous framework of the surface of revolution. Through each point of the surface passes one parallel and one meridian. Similarly, for embossed cladding, the set of all forming relief lines or the set of all parallels of the relief make up the relief surface. However, the lining surfaces, taking into account the relief, are not surfaces of revolution, and in the general case are not even axisymmetric surfaces. In this case, the cladding has an axis, during rotation around which a relief is formed on one or two surfaces of the cladding.

The section of the cladding along the line is a part of the surface passing through a given line perpendicular to the cladding at all points of this a line bounded by the front facing the open part of the charge, and the rear, adjacent to the BB, the lining surfaces.

The middle line of the cladding section is the line passing through the section, at all points equidistant from the inner and outer surfaces of the cladding.

By the waviness of the line is meant the presence of alternating deviations of the line in one direction and in the opposite direction, and the wavelength is the distance between two maximum deviations in one direction. The wavy line can be smooth or stepped. Relief strip - an elongated section of the lining along the generatrix lines of the relief or along parallels, in the sections of which the middle lines are the same. The relief strip may be wavy or waveless in accordance with the mid-lines of the sections.

Stripes of relief without waves are separated by waves of shape and thickness of the lining, going in the direction transverse to these stripes. Stripes of relief without waves visually clearly stand out on the surface of the cladding and give a visual representation of the configuration of the relief; in FIG. 3-10, the relief bands without waves are highlighted in light color.

The implementation of the forming lines of the relief in the form of helical lines is preferable for charges operating in flight with rotation, while the direction and size of the twisting of the lines should be consistent with the direction of rotation of the charge, its longitudinal and angular velocity, as well as the detonation velocity BB.

Cladding with forming relief lines, formed by planes passing through the axis of the cladding (as, for example, in Fig. 17,18), it is advisable to apply for concentrated cumulative charges operating in stationary conditions.

On the lining of FIG. 8-10, two oppositely directed families of generatrix relief lines are made, and, accordingly, two families of relief bands along the facings.

The optimal distribution of the distances between the strips of relief is determined by the material of the cladding 4, its thickness at different areas, as well as the pressure arising from the explosion used BB 2, which depends on its composition and density. The best penetration results are achieved when the wavy middle lines of the sections of the cladding 4 along the generatrix lines of the relief have wavelengths in the range of (0.3 ÷ 0.7) h _obp. UH, where h _o5p. - the average thickness of the lining 4 at the considered wavelength. The ratio UH is determined before calculating the embodiment of the relief of the cladding 4 as described below.

Initial perturbations with a wavelength of L are performed on several plates with a thickness H taken in the range of (0.5 ÷ 1, 5) / 7 _Vol ., Made of the same material as the cladding material. The initial perturbations of the plate are created due to waviness of the form or due to the relief; in the latter case, the relief is performed on the plate surface adjacent to the BB. The easiest way to fulfill the initial perturbations is to grind straight stripes (for example, by milling) on the surface of the plate that will be adjacent to the BB during the explosion.

Each plate is mounted on the end of a piece of the same explosive as used in a cumulative charge and with the same average density; By exploding the checkers, the plate is thrown at a target (for example, a steel plate) located at a distance of 20H ÷ 50H from the plate.

Several of these experiments are carried out, in which either the length of the created initial perturbations L varies with a constant thickness H, or H varies with a constant L. After that, L is selected from the greatest depth of the craters obtained in the target - the wavelength of the most rapidly growing initial perturbations of the plate with a thickness H - and, accordingly, the dimensionless ratio LIH.

In FIG. 11, 12 show the results of experiments to determine the fastest growing initial perturbations of blast-throwing plates. For these experiments, on round plates with a diameter of D = 45 mm and different thicknesses H, taken in the range from 1 to 2 mm, 6 sectors separated by milling with three diametrical strips with a depth of 0.2-0.5 mm and a width of 2-5 mm. Such plates were thrown by cylindrical checkers of phlegmatized RDX with a density of about 1.6 g / cm ³ and a mass of about 80 g from different distances: from 20 to 100 mm. The greatest depth of the craters obtained in the armor plate (Fig. 11) was observed at H = 1, 5 mm and amounted to about 20 mm (Fig. 12). In this setting, L = Yz D cos (tr / 6), and the ratio LIH is 13.

For other sheets of copper and its alloys, depending on the composition of the material and the hardness obtained in the manufacture of the sheets, the LIH ratio varied within 11–15, and the LIH ratio increases with increasing hardness of the sheet material and decreases with its decrease.

If we take into account the above approximate values of the LIH ratio, then for its determination for a specific sheet and used BB it is enough to conduct 5-10 experiments; Of course, the more experiments carried out, the more accurately this parameter can be determined. To straighten the front of the detonation wave in the checker BB, you can install lenses or screens.

In experiments on explosive throwing of metal plates other than copper, it was noted that the indicated ratio for lead plates is less than for copper, and for steel and tungsten - more.

The detonation properties of BB are determined by the detonation velocity and pressure of the detonation products, mainly depending on the composition and density of BB. The kinematic properties of the cladding are the features of mass and momentum transfer caused by the movement of the cladding particles at different points in time: from the start of the detonation wave falling on the cladding to the complete formation of a perforating rod of a certain shape with a certain velocity gradient.

The theoretical solution to the multifactorial problem of matching the detonation properties of the used BB and the kinematic properties of the lining of a specific cumulative charge is associated with great difficulties. However, it has been observed that performing a certain bend on the edge of the cladding from the side of the open part of the housing significantly contributes to the practical solution of this problem. The best results were obtained cumulative charges when performing bending of a length (0,5 ÷ 1, 5) / 7 _obl ./-/H along the lining. In FIG. 13-15 are examples of cladding sections along the generatrix lines of the relief: in FIG. 13 - with a wavy stepped middle line and a bend for facing with a one-sided relief; in FIG. 14 - with the middle line without waves, but with a bend, in FIG. 15 - with a wavy stepped middle line and a bend for corrugated cladding with bilateral relief. The wavelengths along the midline of the cross section I _n generally change for n = 1, 2,3, ..., Λ /, in the preferred cases the condition 0, Zh ₀ Q _n LlH ≤ I _n ≤ OJh _05n UH is _fulfilled . For FIG. 13.15 L / = 9, for other facings N can be any positive integer, in the most common cases the condition 5 <L / <15 is realized.

It is advisable to lining 4 to perform in the form of a lateral surface of a truncated cone, rolled from the workpiece in the form of a flat annular sector. The relief on the workpiece can be made by stamping on a flat ring matrix, for example, in the form of recessed annular sections, alternating with gaps of constant thickness and width, as in FIG. 16.

In FIG. 17 and FIG. 18 shows volumetric images of copper and lead conical linings with a relief on the inner surface and a bend near the base of the cone, which is the preferred manufacturing option. It is also possible to perform cladding in the form of other bodies of revolution: a spherical segment, part of the ellipsoid of revolution, etc.

Qualitative analysis and experiments have shown that a longer maintenance of a high explosion pressure leads to a more effective throwing of the lining and increase the efficiency charge.

When performing the surface of the explosive 2 from the side of the housing 1 with protruding or recessed elements occurs the impact directed along the housing 1, as a result, the impact directed along the normal to the housing is reduced, which helps to maintain the integrity of the charge housing 1 for a longer time. The same effect can be obtained if the inner surface of the housing 1 is made with protruding or recessed elements, and BB 2 is placed in the indicated irregularities during the charge equipment.

It is possible to use a synergistic effect when creating an uneven surface of the explosive from the side of the casing and placing gaskets made of material softer than the casing material on the inner surface of the casing. In this case, the damping of detonation and shock waves incident on the body increases. If a large number of holes or recesses of a sufficiently small diameter are created in the gasket 6, then during an explosion due to the interference of shock waves emanating from different holes or recesses, a curtain is formed that attenuates the waves incident on the body 1 — the “detonation curtain”. The optimum size of the holes or recesses is determined by the detonation ability of the applied BB, a measure of which is the critical detonation diameter d _kp. - the smallest diameter of a cylindrical charge at which detonation still propagates, despite the dispersion of matter from the reaction zone. The detonation ability of BB is greater, the smaller the critical diameter d _kp. . For modern brisant BB d _{cp is} usually a few millimeters.

The experiments showed that the detonation curtain is effective when the size of the perforations or recesses of the gasket is (0.5 ÷ 2) d _cr ., And the distance between them is (1 ÷ 5) d _cr .

In FIG. 23 and 24 show flat reamers (blanks) of gaskets with an angle of the annular sector of 108 ° with different perforations. At when folded, they form gaskets 6 with a solution angle of a truncated cone of 35 °.

Justification of the invention

The lining of the cumulative charge is a working fluid, with the help of which the energy BB is transferred into the work being done. Of most interest are thin metal cladding, as when they are thrown, it is better to transfer momentum from detonation products to the lining, and also, due to the low surface density, high throwing speeds are achieved. In this case, the density of the resulting rod (the density of the metal used) is high enough for effective penetration of the barrier.

Two approaches are mainly used to calculate the explosive compression of thin linings. In one approach, it is assumed that a solid lining material under the influence of a large pressure drop instantly turns into a liquid, and a model of an ideal incompressible liquid is used. With another approach, on the contrary, despite the fact that the pressure drop is much larger than the plastic elastic limit of the material, it is implicitly accepted that the material does not undergo radical rheological changes, and numerical methods based on models of material behavior under ordinary conditions are used.

However, new theoretical and experimental studies have established the following. When the detonation wave falls on the surface of the lining and the further passage of the shock and reflected waves, numerous spalls occur, as a result of which the lining material delaminates. It acquires a structure similar to a liquid crystal. (This refers to the analogy with the fact that liquid crystals do not have a rigid crystal lattice, but have a partial spatial order of molecules in some directions.)

In this regard, for the design and calculation of cumulative charges in order to achieve the best technical result it is advisable to use a model of weakly elastic lining, in which it is assumed that at the very early stage of acceleration of the lining new properties of an elastoplastic material are developed, namely, longitudinal elasticity with an elastic modulus proportional to the applied explosion pressure.

When calculating the intersection of the trajectories of the particles of the lining, a model of absolutely inelastic impact is used; those. it is assumed that upon collision of the cladding areas, the particles stick together, as a result of which rods, rings or cores are formed. In order to get rid of the consideration of possible gas leakage onto the front surface of the cladding and the analysis of the resulting rarefaction waves, we consider the cladding placed in a channel of the corresponding shape, i.e. deformable piston.

The conducted experimental studies have shown that there is a material constant that is not related to ordinary elastic modules characterizing the indicated weak elasticity - a constant of weak elasticity. The determination of this constant based on the kinetics of destruction (spalling) is difficult and irrational. Moreover, this constant depends not only on the cladding material and applied pressure, but also on the manufacturing process (for example, a sheet of copper can be in a solid, semi-solid and soft state). It does not depend only on the thickness (of course, for sufficiently thin linings, for example, for copper - less than 4 mm). It is easier to conduct a series of experiments and determine the constant of weak elasticity for a particular material and used BB by statistical processing of the experimental results.

For a mathematical description of the above facts, we introduce the Cartesian coordinate system x '(/ = 1,2,3), and let r be the radius vector of the particles of the cladding with the Euler components x ^ι . Then the equations of motion of the weakly elastic lining have the form , 2 αβ,

Here σ is the surface density of the cladding, n is the unit normal vector, directed towards the absence of pressure. The subscript t denotes the time derivative with constant Lagrangian coordinates ξ ^α (α = l, 2), and the subscript β denotes the derivative with respect to ξ. The symbol V means the covariant derivative along the surface.

The pressure p _{Q is} further considered constant. The value of c is the characteristic of the longitudinal elasticity of the cladding material. It is introduced by the formula c = ee /? ₀ / p, where p (ξ ^α ) is the density of the cladding material (considered incompressible), ae is the constant of weak elasticity, dimensionless coefficient, for metal cladding of the order of 1; the value of c can conditionally be called the square of the speed of sound in the cladding material. We also introduce the thickness of the lining h - σ / p.

Note that we obtain the model of purely inertial throwing by formally setting c - 0.

Let a _a p be the components of the metric tensor of the facing surface

Here δ ^ is the Kronecker symbol, X ^ are the components of the tangent vectors

of the surface l ^* _α , so that = = Γ, x T ₂ / | R, x Y ₂ \, and

I g, χ r ₂ | = (det (α _αβ )) ≡ JΞ.

The symbol I _Q denotes the initial contravariant components of the metric surface tensor that are used with

2 by coefficient c as components of the specific tensor of elastic constants. We note that all the elements of the theory of finite cladding deformation without linearization are sequentially taken into account here, although ultimately the elastic component of the stress tensor is linear. Indeed, by the law of conservation of mass, the Lagrange formula is valid

The zero index, as above, marks the corresponding initial quantities - the functions ξ ^α . As a result, we obtain the vector equation

σo 4 ^® o ^{~ r} , _t = Po ^r i ^xr 2 + (V ^ σ ₀ c ² < ^p g _p

3 about. 2 In the case of a plane problem, we have x = ς, all other variables are functions ξ and t. We introduce the complex Euler

the variable z = x + ix, and also, to simplify the equations, we use the following mass variable as the Lagrangian coordinate:

7 ^{I / 2} μ = рώ- rfξ ¹ .

Po

Moreover, σ = Po / \ ^z _μ I - The dimension of the variable μ is equal to the dimension t ² .

Then the equations of motion take the form zu = ^{/ z} μ ⁺ (c ² (μИ) _μ > c ² = ze ≠ o / p _o - This complex equation is a system of two hyperbolic equations, but even with a constant value c it has a strong dispersion, which in many respects characterizes the unusual behavior of solutions with different initial data.

Indeed, in the case c = SOPSt we consider an elementary solution that locally corresponds to cylinder deformation. Let be Z = A ₀ Qxp (λt - i кμ), σ = - - - exp (-Reλ t),

14, 1 * where A _ϋ , λ are complex constants, k> 0 is a real constant. Then we get the dispersion equation

which shows the following.

There is a critical wave number k _cr - \ / c, corresponding to the equilibrium state λ = 0. For wave numbers k <k _{cr, the} constant λ is real, which corresponds to either an increase or decay of the wave amplitude A ₀ QXpXt with time. There is only one maximum.

λ with k = k _cr / 2. So there is a wave with

mass length 4πc, called the "resonance", with the fastest growing amplitude, which characterizes the maximum instability of the process. In ordinary linear variables, this gives the relation

4πaeσ _o / z _o = σ _o α _o 1/2 d jξ ^j - 1 = const,

which is approximate (since the value of σ _o α _o , generally speaking, is not constant) corresponds to the wavelength / _g «4πae / ^. When k -> 0, the amplitude growth rate decreases to zero.

In the case k> k _{ct, the} parameter λ becomes purely imaginary: λ = / ω, where CO is the frequency of the oscillations of the amplitude that is periodic in time.

Thus, the qualitative behavior of a relief lining during explosive throwing is characterized by the wavelength of the initial disturbances due to the shape and relief of the lining. The process of development of short waves occurs in an oscillatory mode. Must keep in mind that for the application of the theory, the real wavelength should be much larger than the characteristic thickness of the cladding, which limits the spectrum of wavelengths from below.

Further, as it increases, there is a critical wavelength when the oscillation frequency vanishes. When creating perturbations with a critical wavelength, perturbations do not grow, and spontaneous ones are suppressed if their amplitude is sufficiently small compared to the amplitude of artificially created ones.

When creating initial disturbances with a wavelength greater than the critical disturbances grow; this range, in turn, has a resonant wavelength equal to twice the critical, with the largest growth increment. With a further increase in the wavelength, the increment decreases to zero.

The main problem that developers face when designing explosive devices with thin linings is their dynamic instability (it is also called the Rayleigh-Taylor instability or accelerator instability).

An inertia force acts in the reference system associated with the median surface of the throwable cladding, which, roughly speaking, presses the front (in the throwing direction) surface of the cladding, but makes its back surface, initially adjacent to BB, unstable, from which significant parts of the cladding material can be separated .

Therefore, to create large deformations of the cladding, it is advisable to perform the initial perturbations on the surface adjacent to the BB — this is necessary to determine the resonant wavelength equal to twice the critical; and in order to suppress fluctuations and increase initial disturbances, the lining waviness required to create a critical throwing regime must be created due to the relief on the front side of the lining.

The solution to the problem of acceleration instability is as follows: for any cladding and used BB there the critical length of the initial perturbations, at which they do not grow, and the growth of spontaneous perturbations is suppressed if their amplitude is sufficiently small compared to the amplitude of artificially generated ones.

The work of the proposed device The proposed cumulative charge works as follows. When the triggering device 3 is triggered, detonation BB 2 and explosive throwing of the relief cladding 4 occur. When performing on the surface facing the open part of the body of the relief cladding aimed at the formation of wavy middle lines in the respective sections of the cladding, after detonation BB there are deformation conditions favorable to reduce instability facing, and in the case of creating a wavelength close to critical - to the most possible elimination of oscillations and growth of disturbances. In this case, energy dissipation associated with fluctuations and an increase in spontaneous perturbations decreases, a more accurate throwing of the lining occurs, the formation of a perforating rod of an optimal shape with calculated parameters, and the efficiency increases charge and stability of its work. Using the solution of the problem of throwing a cladding of a given shape with explosion pressure, taking into account the finiteness of the detonation velocity, it is possible to realize the most uniform deformation of the cladding when it passes to the perforating rod.

A perforating rod provides hole formation (perforation), for example, in a well casing. The charge housing 1, usually made of steel or other durable material, serves to reliably install the charge in a suitable device near the target (for example, in a perforator housing inside the borehole) and to keep the explosion pressure; gaskets 6 reduce the explosive effect on the charge body 1, which leads to an increase in the energy directed to throwing the cladding 4. To solve the problem, the real possibility is used to set the optimal process for the development of the initial perturbations of the cladding 4 at high accelerations arising from the explosion. The shape of the lining 4 is consistent with the solution of the problem of throwing and dispersing the initially resting lining.

As a result, the material of the original cladding 4 during the movement flows into a fairly homogeneous low-gradient (meaning the velocity gradient) perforating rod of an optimal bullet shape with a high momentum. In addition, the specified rod has good aerodynamic characteristics, but this advantage is usually not used due to the tightness of the conditions for the use of cumulative charges. In addition to increasing efficiency and stability, the proposed cumulative charge has the following advantages.

There is no need to design complex claddings. It is enough to choose the simplest and most technologically advanced form (for example, a conical cladding with a solution angle of 39 °, rolled from a copper sector with an angle of 120 °), but due to the caliber, thickness and relief of the cladding, the required penetration parameters can be obtained in the widest range, while the volume of the obtained channel in the target can exceed the volume of penetration of a traditional charge with the same mass BB by 2-2.5 times. This increases the stability of the charges: from 7-8 successful shots from 10 shots (for currently used) to 9 out of 10 (for the proposed charge). Successful shots are usually taken as those in which the deviations of the hole diameter and channel depth from the required values are no more than 10%. You can lower the requirements for workmanship. A cut on the lining at the junction of the edges of the workpiece, if it is made along the relief line, does not affect the work of the cumulative charge; for smooth cladding, the incision leads to negative consequences. Relief cladding 4 can be performed from a sheet (tape) in a simple mechanical way (cutting, stamping, convolution and mandrel), and smooth cladding requires more complex operations (rolling, drawing, etc.). Reducing the requirements for the quality of manufacture of cladding reduces the cost of manufacturing embossed cladding, however, it becomes extremely important the exact execution of the relief. An error in the relief of 10 μm leads to a deterioration in the parameters of penetration (although high stability is maintained). The issue of the quality of the relief is solved by the exact calculation and manufacture of stamping dies, which at the current level of development of computer technology and metalworking equipment does not present great difficulties. High results of the proposed charge are achieved without the use of expensive metals and alloys. Increased penetration and stability are achieved by eliminating instability during compression of the cladding, reducing energy dissipation and increasing momentum without increasing the cost of the cladding material. In addition, the relief cladding can be calculated and performed so that when it is compressed there will be neither a thin unstable stream nor a low-speed pestle.

Industrial applicability The declared cumulative charge can be mass-produced in industrial production using existing equipment and the use of modern manufacturing technology. Technological means of implementing the invention at the current level of production development are quite diverse.

Examples of the implementation of the proposed device Example 1. To compare the efficiency and stability of the cumulative charges with reliefs made on different sides of the lining was made a batch of cumulative charges. Each charge contained a steel case with a diameter of 48 mm, a length of 60 mm, with a shape similar to that shown in FIG. 1. Inside the housing was placed 24 g of BB based on RDX phlegmatized with an average density of about 1.6 g / cm ³ . The initiation system consisted of an electric detonator adjacent to it a detonating cord and an intermediate detonator in the form of a compressed crystalline hexogen.

Of the copper sheet with a thickness of 0.6 mm, 10 billets were made with an angle of the annular sector of 120 °, an outer diameter of 125.5 mm and an inner diameter of 38 mm. On the blanks by stamping on a flat ring matrix, the same relief was made, similar to that shown in FIG. 16, with a wavelength of about 4 mm. Then half of them were folded in relief outward, and half - inward relief. The surface opposite to the one on which the relief was made was smooth. The angle of the solution of the truncated cone was 39 °, the diameter of the base was 42 mm, the diameter of the upper part was 13 mm, the height was 41.5 mm, and the mass was about 19 g. A bend with a length of 8 mm and an amplitude was made from the base of the cone along its generators 0.5 mm Each of the facings manufactured in this way was pressed into a cumulative recess with an angle of 39 °, previously made in BB by pressing from the side of the open part of the housing. On the inner wall of the charge casing before pressing BB, a perforated gasket was rolled up from a copper billet with a thickness of 0.8 mm, made according to the sketch of FIG. 23, in the form of a lateral surface of a truncated cone with a solution angle of 35 °.

The target consisted (from bottom to top) of a steel column with a diameter of 70 mm, a steel sleeve filled with water, 12.5 mm high and a 5 mm thick steel plate. The charge was mounted on the specified target with a focal length of 9 mm. Such tests are carried out to debug the perforating charges used for the secondary opening of oil and gas reservoirs. In particular, these charges relate to “Big HoIe” punch charges.

The channels obtained in steel columns were measured with a caliper with a depth gauge. The measurement results are summarized in table. one.

Table 1

Given in the table. 1 results indicate the following.

If the relief is located outside the lining, and after it is pressed into the cumulative recess, the relief is adjacent to this recess, then low values and a large scatter of the results of penetration of the targets are observed. If the relief is located inside the lining, and after pressing it in, the relief faces the open part of the charge body, then high efficiency and stability of the charges are observed.

Example 2. To experimentally confirm the results of a theoretical analysis of optimizing the wavelength of the initial perturbations of the cladding, a batch of cumulative charges similar to those described in Example 1 was manufactured with exactly the same bodies, BBs, gaskets and claddings with a relief on the front side. The difference was that the middle lines of the cladding sections along the generatrix lines of the relief had different wavelengths on different claddings. In preliminary experiments, it was found that for the cladding material and BB used in these charges, LIH = 13.5, / 7 _Obl . = 0.6 mm. The results of breaking through the above targets are shown in table. 2. table 2

Given in the table. 2 results indicate the following.

When the wavelengths of the middle lines of the sections of the linings along the generatrix lines of the relief are greater than OJh ₀ Q _n UH (8 mm and 6 mm), the results of the charges are low, the spread is large. In the range of relief wavelengths (0.3 ÷ 0.7) h _ОБП L / H (5 mm, 4 mm, 3.5 mm and 3 mm), the charges work more efficiently and more stably; waves less than 0, Зh _O Q _П L / H for copper are too short. The best results are observed at a wavelength of relief close to 0.5h _o6l UH (4 mm). This confirms the theoretical conclusions about the feasibility of implementing a critical regime of explosive throwing of facings. Example 3. To perforate a steel plate with a thickness of 300 mm, charges were made with an outer diameter and height of 48 mm and 80 mm, respectively. Weighed charges - 35 g of phlegmatized RDX. Facings were made of copper sheet with a thickness of 0.6 mm in the form of a lateral surface of a truncated cone with a solution angle of 19 °; the diameter of the base was 40 mm, the diameter of the upper part was 21 mm, the height was 58 mm, and the mass was 28.5 g. On the front side there is a relief similar to that shown in FIG. 16.

After undermining these charges mounted on a steel plate, through holes with inlet and outlet diameters of 15 mm and 10 mm, respectively, were formed in it.

Example 4. When carrying out emergency repairs, cumulative charges were used, similar in shape to those described in Example 1, containing 50 g phlegmatized octogen, two gaskets (lead on the body and perforated copper adjacent to BB) and copper linings with a thickness of 0, 8 mm, made in the form of a spherical segment with a solution angle of 120 °, with a relief on the inside facing the open part of the housing; the diameter of the base of the cladding was 50 mm; the wavelength of the relief was about 5 mm.

20 of these charges, inserted into a plastic tape with holes for installing charges, were placed close to each other and mounted in the form of a circle on a brick-concrete wall with a thickness of about 500 mm. From the closed part of the charges, a detonating cord with an electric detonator and wires brought to a safe place was strengthened. After a simultaneous explosion of charges, a hole with a diameter of about 500 mm was formed in the plate.

Example 5. Charges similar to those described in example 4 were used to separate steel plates. The charges were placed close to each other along the cutting lines and were initiated simultaneously by a detonating cord. Cylindrical holes with diameters close to the gauge of charges were formed in the plates, and in bridges strong spalling processes took place between them. As a result, steel plates were divided along predetermined lines.

To create the 1 m section in the specified way in steel to a depth of about 100 mm, 5-10 times less BB is required compared to traditional elongated cumulative charges.

Example 6. When carrying out construction work, a charge with a copper corrugated lining with a thickness of 1.5 mm was used as part of a rotation ellipsoid. The mass of the BB charge was 300 g, the diameter of the base of the cladding was 100 mm, and the wavelength of the relief was about 10 mm. After undermining this charge, a hole was formed in the rock with a diameter of about 50 mm and a depth of more than 1 m, in which a BB charge was placed for blasting operations to discharge.

The above examples do not exhaust the possibility of using the proposed cumulative charge. At the same time increased efficiency and breakdown ability of the charge by eliminating energy losses associated with fluctuations and an increase in initial disturbances, as well as increased accuracy and stability of explosive throwing of the cladding with the formation of a uniform perforating rod of an optimal bullet configuration, achieved due to the presence of specially created optimized inhomogeneities (relief) on the corresponding surfaces of the cladding and the presence of irregularities on the surface of the explosive, formed, for example, using a gasket. At the same time, manufacturing costs are reduced and the stability of the results of use is ensured.

Claims

Claim

1. A cumulative charge containing an enclosure in the form of an open shell, an explosive placed inside it with a cumulative recess located in the open part of the body, an initiation device located in the closed part of the body, and a relief cladding adjacent to the cumulative recess, such that the medium the lines of the cladding sections along the generatrix lines of the relief, as well as the middle lines of the cladding sections by planes perpendicular to the axis of the cladding, are either wavy lines or lines without flax, while the wavy center lines can be smooth or stepped, characterized in that the relief is made either on the facing surface facing the open part of the body, or on both surfaces of the facing. 2. The cumulative charge according to claim 1, characterized in that the cladding is corrugated, that is, the reliefs on both surfaces of the cladding coincide, while the relief protruding on one surface corresponds to the protrusion of the relief on the opposite surface of the cladding. 3. The cumulative charge according to any one of paragraph 1,

2, characterized in that the wavy middle lines of the cladding sections along the generatrix lines of the relief have wavelengths in the range (0,

3 ÷ 0.7) h _ObP. L / H, where: h _Obp is the average thickness of the lining at the considered wavelength, L is the wavelength of the most rapidly growing initial perturbations of the plate with a thickness H taken in the range (0.5 ÷ 1.5) L _O bl made from the same material as the cladding material, empirically determined by the greatest depth of craters in the target, obtained by throwing a plate on a target located at a distance of 20H ÷ 50H from the plate using an explosive used in a cumulative charge. The initial perturbations of the plate are created due to the undulation of the form or due to the relief; at in the latter case, the relief is performed on the surface of the plate adjacent to the explosive block.

4. The cumulative charge according to p. 3, characterized in that on the edge of the cladding from the side of the open part of the housing along the cladding, a bend with a length of (0.5 ÷ 1.5) /? _About l UH.

5. The cumulative charge according to claim 3, characterized in that the lining is made in the form of a lateral surface of a truncated cone with a relief in the form of recesses and protrusions, the distances between the midpoints of adjacent recesses and the distances between the midpoints of adjacent protrusions measured along the generatrices of the cone (0.3 ÷ 0.7) / 7 _O bl UH.

6. The cumulative charge according to claim 5, characterized in that the lining is made of a workpiece in the form of a flat ring sector by folding, and the relief on the workpiece is made by stamping on a flat ring matrix.

7. The cumulative charge according to any one of paragraphs. 3-6, characterized in that the lining is made of a sheet of copper or its alloys with a thickness of 0.4 ÷ 4.0 mm, and the ratio LIH increases with increasing hardness of the sheet material and decreases with its decrease in the range of 11 ÷ 15.

8. The cumulative charge according to claim 1, characterized in that the surface of the explosive from the side of the shell is made with protruding or recessed elements.

9. The cumulative charge according to claim 1, characterized in that the inner surface of the housing is made with protruding or recessed elements, and the explosive fills these irregularities.

10. The cumulative charge according to claim 1, characterized in that it is provided with one or more gaskets located between the explosive and the body, partially or completely separating the explosive and the charge body, the gasket adjacent to the inner side of the body being made of a softer material, than the body material.

11. The cumulative charge according to claim 10, characterized in that the gasket adjacent to the explosive is made with holes or recesses, and the explosive fills these holes or recesses in the gasket.

12. The cumulative charge according to claim 11, characterized in that the size of the perforations or recesses in the gasket is (0.5 ÷ 2) o'cr., And the distance between them is (1 ÷ 5) d _K p-, where d _kp . - the critical diameter of the detonation used in the charge BB.