US20220373306A1

US20220373306A1 - Linear shaped charge backstop

Info

Publication number: US20220373306A1
Application number: US17/326,737
Authority: US
Inventors: Catherine Johnson; Jason Ho
Original assignee: University of Missouri System
Current assignee: University of Missouri System
Priority date: 2021-05-21
Filing date: 2021-05-21
Publication date: 2022-11-24

Abstract

A linear shaped charge includes a sheath having an open end and an opposite closed end. A peripheral wall extends longitudinally from an end wall a predetermined length. The peripheral wall has a first wall thickness and the end wall has a second wall thickness. The second wall thickness of the end wall is equal to or greater than the first wall thickness of the peripheral wall. The peripheral wall and the end wall cooperatively define a cavity. The linear shaped charge also includes an explosive material disposed within and substantially filling the cavity.

Description

FIELD OF THE DISCLOSURE

The embodiments described herein relate generally to linear shaped charges, and more particularly, to a linear shaped charge having an attached “backstop” to facilitate reducing run-down, thereby increasing an overall cut length of the linear shaped charge.

BACKGROUND

Generally, a linear shaped charge (LSC) is an explosive device having an explosive material sheathed in a specially shaped tube or sheath. The sheath typically has six flat faces arranged generally in an inverted “V” shape. The inner legs of the inverted “V” meet at an apex, and upon detonation of the LSC, collapse together in face-to-face contact to form a blade of sheath material.
Known LSCs are typically open-ended, which results in run-up and run-down areas. FIG. 1 depicts a sectioned target 10 including an example prior art cut profile 12 produced by a typical prior art LSC (not shown). The cut profile 12 is defined by three zones: run-up zone 14, cut zone 16, and run-down zone 18. The run-up zone 14 is the area of suboptimal cut depth on the end of the target 10 where the LSC was initiated. The cut zone 16 is the area where there was a stable, substantially horizontal cut depth. The run-down zone 18 is the area of suboptimal cut depth on the end of the target 10 opposite the initiation point. The run-down zone 18 is defined by a decrease in the cut depth from the cut zone 16 to a point where there is no longer any cut. The run-up and run-down zones 14 and 18 result a loss of a portion of the cut zone 16. This results in loss of detonation efficiency of the LSC and increased costs.

SUMMARY

This summary is provided to introduce a selection of concepts in a simplified form that are further described in the detailed description below. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. Other aspects and advantages of the present disclosure will be apparent from the following detailed description of the embodiments and the accompanying drawing figures.
In one aspect, a linear shaped charge is provided. The linear shaped charge includes a sheath having a peripheral wall extending longitudinally a predetermined length. The sheath includes an open end and an opposite closed end. The closed end is defined by an end wall. The peripheral wall has a first wall thickness and the end wall has a second wall thickness. The second wall thickness is equal to or greater than the first wall thickness. The peripheral wall and the end wall define a cavity. The linear shaped charge also includes an explosive material located within and substantially filling the cavity.
In another aspect, a method is provided. The method includes fabricating a sheath of a linear shaped charge. The sheath includes a peripheral wall including an open end and an opposite closed end. The closed end is defined by an end wall. The peripheral wall has a first wall thickness and the end wall has a second wall thickness. The second wall thickness is equal to or greater than the first wall thickness. The peripheral wall and the end wall define a cavity. The method also includes filling the cavity with an explosive material.
Advantages of these and other embodiments will become more apparent to those skilled in the art from the following description of the exemplary embodiments which have been shown and described by way of illustration. As will be realized, the present embodiments described herein may be capable of other and different embodiments, and their details are capable of modification in various respects. Accordingly, the drawings and description are to be regarded as illustrative in nature and not as restrictive.

BRIEF DESCRIPTION OF THE DRAWINGS

The Figures described below depict various aspects of systems and methods disclosed therein. It should be understood that each figure depicts an embodiment of a particular aspect of the disclosed systems and methods, and that each of the figures is intended to accord with a possible embodiment thereof. Further, wherever possible, the following description refers to the reference numerals included in the following figures, in which features depicted in multiple figures are designated with consistent reference numerals.

FIG. 1 is a sectioned target including an example prior art cut profile produced by a typical prior art linear shaped charge;

FIG. 2 is a front perspective view of an exemplary linear shaped charge (LSC), in accordance with one aspect of the present invention;

FIG. 3 is a rear perspective of the LSC of FIG. 2;

FIG. 4 is a sectional view of the LSC of FIG. 2, taken about the plane 4-4 shown in FIG. 3;

FIG. 5 depicts a sectioned target including an example cut profile produced by LSC of FIG. 2, including a backstop;

FIG. 6A is a rear perspective, partial exploded view drawing of an alternative LSC;

FIG. 6B is a perspective of an alternative backstop for use with the LSC shown in FIG. 6A;

FIG. 7 is a rear perspective, partial exploded view drawing of another alternative LSC;

FIG. 8 is a rear perspective of yet another alternative LSC;

FIG. 9 is a rear perspective, partial exploded view drawing of the alternative LSC shown in FIG. 8;

FIG. 10 is a front perspective of a cap backstop of the LSC shown in FIG. 8;

FIG. 11 is a front view of the cap backstop of FIG. 10;

FIG. 12 is a side section view of the cap backstop of FIG. 11, taken about line 12-12 shown in FIG. 11;

FIG. 13 is a front perspective of an alternative cap backstop;

FIG. 14 is a front view of the cap backstop of FIG. 13; and

FIG. 15 is a side section view of the cap backstop of FIG. 14, taken about line 14-14 shown in FIG. 14.

Unless otherwise indicated, the drawings provided herein are meant to illustrate features of embodiments of this disclosure. These features are believed to be applicable in a wide variety of systems comprising one or more embodiments of this disclosure. As such, the drawings are not meant to include all conventional features known by those of ordinary skill in the art to be required for the practice of the embodiments disclosed herein. While the drawings do not necessarily provide exact dimensions or tolerances for the illustrated components or structures, the drawings are to scale with respect to the relationships between the components of the structures illustrated in the drawings.

DETAILED DESCRIPTION

The following detailed description of embodiments of the disclosure references the accompanying figures. The embodiments are intended to describe aspects of the disclosure in sufficient detail to enable those with ordinary skill in the art to practice the disclosure. The embodiments of the disclosure are illustrated by way of example and not by way of limitation. Other embodiments may be utilized, and changes may be made without departing from the scope of the claims. The following description is, therefore, not limiting. The scope of the present disclosure is defined only by the appended claims, along with the full scope of equivalents to which such claims are entitled.
In this description, references to “one embodiment,” “an embodiment,” or “embodiments” mean that the feature or features being referred to are included in at least one embodiment of the technology. Separate references to “one embodiment,” “an embodiment,” or “embodiments” in this description do not necessarily refer to the same embodiment and are also not mutually exclusive unless so stated and/or except as will be clear to those skilled in the art from the description. For example, a feature, structure, act, etc. described in one embodiment may also be included in other embodiments but is not necessarily included. Thus, the present technology can include a variety of combinations and/or integrations of the embodiments described herein.
In the following specification and claims, reference will be made to several terms, which shall be defined to have the following meanings. The singular forms “a,” “an,” and “the” include plural references unless the context clearly dictates otherwise. “Optional” or “optionally” means that the subsequently described event or circumstance may or may not occur, and that the description includes instances where the event occurs and instances where it does not.
Approximating language, as used herein throughout the specification and the claims, may be applied to modify any quantitative representation that could permissibly vary without resulting in a change in the basic function to which it is related. Accordingly, a value modified by a term or terms, such as “about,” “approximately,” and “substantially” are not to be limited to the precise value specified. In at least some instances, the approximating language may correspond to the precision of an instrument for measuring the value. Here and throughout the specification and claims, range limitations may be combined and/or interchanged. Such ranges are identified and include all the sub-ranges contained therein unless context or language indicates otherwise.
As used herein, directional references, such as, “top,” “bottom,” “front,” “back,” “side,” “upward,” “downward,” and similar terms are used herein solely for convenience and should be understood only in relation to each other. For example, a component might in practice be oriented such that faces referred to herein as “top” and “bottom” are in practice sideways, angled, inverted, etc. relative to the chosen frame of reference.

Exemplary Linear Shaped Charge Sheath

FIG. 2 is a front perspective view of an exemplary linear shaped charge (LSC) 20, in accordance with one aspect of the present invention. FIG. 3 is a rear perspective of the LSC 20. FIG. 4 is a sectional view of the LSC 20, taken about the plane 4-4 shown in FIG. 3. In the exemplary embodiment, the LSC 20 includes a sheath 22 and an explosive material 25 encased within the sheath 22. The sheath 22 has a generally inverted V-shaped cross sectional peripheral wall 23. The sheath 22 extends longitudinally along a linear axis a predetermined length “L.” The peripheral wall 23 is substantially symmetrical about a centerline “L.” More particularly, the sheath 22 includes six (6) sides defining the peripheral wall 23: inner legs 24 and 26, sidewalls 28 and 30, and upper walls 32 and 34. In an example, the inner legs 24 and 26 are substantially parallel to the upper walls 32 and 34, respectively. In the example, the intersection of each pair of adjacent sides defines a smooth radiused transition. This facilitates manufacturing the sheath 22 by reducing cracking and/or breaking along the intersection. In certain other embodiments, for example, sheaths fabricated by additive manufacturing techniques, the intersection of each pair of adjacent sides need not include a smooth radiused transition.
In the exemplary embodiment, the LSC 20 extends longitudinally a predefined length “L,” in which the inverted V-shaped peripheral wall 23, and in particular, the inner legs 24 and 26, the sidewalls 28 and 30, and the upper walls 32 and 34 define a cavity 40 for receiving the explosive material 25 therein. While depicted herein as having an inverted V-shaped periphery, it is contemplated that the LSC 20 may have various shapes including, but not limited to, an annular-shaped periphery, a quadrilateral-shaped periphery, a polygonal-shaped periphery, and/or any other shape that enables the LSC 20 to function as described herein.
In the exemplary embodiment, the explosive material 25 substantially fills the cavity 40 of the sheath 22. The explosive material 25 is typically a high explosive with a high detonation velocity and pressure. The explosive material may include, for example, and without limitation, one or more of the following: RDX, which has a detonation rate of about eight thousand, two hundred meters per second (8,200 m/s); HMX (octogen), which has a detonation rate of about nine thousand, one hundred meters per second (9,100 m/s); PETN, which has a detonation rate of about eight thousand, three hundred meters per second (8,300 m/s); HNS, which has a detonation rate of about six thousand, nine hundred meters per second (6,900 m/s); and PYX, which has a detonation rate of about seven thousand, two hundred meters per second (7,200 m/s). It is noted, however, that the explosive material 25 may include any explosive that enables the LSC 20 to function as described herein.
In the exemplary embodiment, the LSC 20 has initiation end 36, in which the explosive material 25 is exposed (i.e., the sheath is open-ended), and a closed end 38, in which the explosive material 25 is covered by a backstop 42 (broadly, an end wall). The sheath 22 extends longitudinally between the initiation end 36 and the closed end 38. In the exemplary embodiment, the backstop 42 facilitates directing explosive energy from the explosive material 25 in a desired direction. In particular, the backstop 42 reduces or limits the explosive energy from escaping from the end of the LSC 20 opposite initiation. This facilitates increasing an amount of the explosive energy exerted on the six (6) sides of the LSC 20, and in particular, the inner legs 24 and 26, which facilitates reducing or eliminating a run-down zone of the cut profile.
FIG. 5 depicts a sectioned target 50 including an example cut profile 52 produced by LSC 20 including the backstop 42. In this example, the cut profile 52 includes two (2) zones: a run-up zone 54, and a cut zone 56. As opposed to the prior art cut profile 12 depicted in FIG. 1, the cut profile 52 does not include a run-down zone. That is, the exemplary sheath 22 of the present invention substantially eliminated the typical run-down zone of known LSC cut profiles, thereby increasing a length of the cut zone, as a percentage of the overall cut profile.
Referring to FIGS. 2-4, the inner legs 24 and 26, the sidewalls 28 and 30, and the upper walls 32 and 34 have a substantially identical wall thickness “T₁.” The backstop 42 has a wall thickness “T₂.” In one embodiment, the wall thickness T₂of the backstop 42 is greater than and including about one (1) times the wall thickness T₁. In an example, the wall thickness T₂of the backstop 42 is in a range between and including about one (1) times the wall thickness T₁and about three (3) times the wall thickness T₁. In another embodiment, the wall thickness T₂of the backstop 42 is greater than and including about two (2) times the wall thickness T₁. Additionally, in a preferred embodiment, the wall thickness T₂of the backstop 42 is in a range between and including about two (2) times the wall thickness T₁and about three (3) times the wall thickness T₁. It has been found that when the backstop 42 is 2× and 3× the wall thickness T₁of the peripheral wall 23, the percentage of cut length that can be classified as run-down is substantially less than one percent (1%).
Table 1 includes the results of several penetration tests that were performed according to the preferred embodiments of the present invention where the wall thickness T₁was seven hundredths of an inch (0.07 in).

TABLE 1

		% of Cut	Maximum	Ratio of Backstop
		Profile	Depth	Thickness to
	Density of	Length that is	Penetration	Sidewall
Test	C4 (g/cm³)	Run Down	(in)	Thickness

No	1.600	17.00%	0.54	N/A
backstop
(Control)
0.07 in	1.599	1.01%	0.64	1:1
backstop
0.14 in	1.598	0%	0.63	2:1
backstop
0.21 in	1.600	0%	0.60	3:1
backstop

As illustrated in Table 1, testing indicated that an LSC sheath, such as sheath 22, including a backstop, such as backstop 42, substantially decreases or even eliminates a run-down zone of an LSC cut profile.
In one embodiment, the sheath 22 is a unitary component fabricated using an additive manufacturing process. Typically, additive manufacturing processes involve the use of an energy source for emitting a focused energy beam to consolidate a powdered material (e.g., melting and solidifying particles of a powdered material) for forming a component, such as the sheath 22, comprising a series of layers of solidified material. Such processes produce geometrically complex components from powdered materials at a reduced cost and with improved manufacturing efficiency as compared to traditional manufacturing techniques. It is noted that the sheath 22 can be fabricated using any powder bed fusion process that enables the sheath 22 to be fabricated as described herein. For example, and without limitation, such additive manufacturing processes include Direct Metal Laser Melting (DMLM), Direct Metal Laser Sintering (DMLS), Selective Laser Sintering (SLS), Selective Laser Melting (SLM), and Electron Beam Melting (EBM) systems. However, in alternative embodiments of the present invention, the sheath 22 may be fabricated using, for example, machining, casting, molding, extrusion, and any other fabrication process that enables the sheath 22 to be fabricated as a unitary component as described herein.
In one suitable embodiment, the sheath 22 is fabricated from a metal, for example, and without limitation, steel, aluminum, titanium, and the like, using an extrusion process. Alternatively, the sheath 22 can be fabricated from any material that enables the sheath 22 to function as described herein, such as, for example, and without limitation, composite materials, ceramics, resins, fiber reinforced resins, plastics, fiber reinforced plastics, and the like.
Linear Shaped Charge Sheath with Plate Backstop
FIG. 6A is a rear perspective, partial exploded view drawing of an alternative LSC 60. In this embodiment, a sheath 62 is formed substantially similar to the sheath 22 described above. However, in the illustrated embodiment, a backstop 64 is fabricated as a separate component and is coupled to the sheath 62. In the exemplary embodiment, the sheath 62 has a periphery 66 (which is substantially the same peripheral size and shape as the peripheral wall 23, described above) defining an outer boundary of the sheath 62. The backstop 64 has a periphery 68 that is substantially the same size and shape as the periphery 66.
In the example embodiment, the wall 69 of the sheath 62 has a substantially continuous wall thickness “T₃.” The backstop 64 has a wall thickness “T_4A.” As described above with respect to the LSC 20, the wall thickness T_4Aof the backstop 64 is in a range between and including about two (2) times the wall thickness T₃and about three (3) times the wall thickness T₃.
In an example embodiment, the sheath 62 may fabricated from a metal, for example, and without limitation, steel, aluminum, titanium, and the like, using an extrusion process. For example, the metal may be formed in the described inverted V-shaped cross section and extruded or drawn to a predetermined length. The backstop 64 may be coupled to the sheath 62 via a permanent coupling method including, for example, and without limitation, an adhesive bond, a weld joint (e.g., spin welding, ultrasonic welding, laser welding, or heat staking), and the like. Alternatively, the backstop 64 and the sheath 62 may be coupled together using any connection technique that enables the LSC 60 to function as described herein. The explosive material 25 may then be packed into the cavity of the sheath, such as the cavity 40 described above, to form the LSC.
FIG. 6B is a perspective of an alternative backstop 65 for use with the LSC 60 shown in FIG. 6A. In the depicted embodiment, the backstop 65 is substantially similar to the backstop 64 (shown in FIG. 6A), except that the backstop 65 omits the inner inverted “V” shaped portion of the periphery 68 of the backstop 64. Rather, the depicted backstop 65 includes a substantially planar base wall portion 67 of a periphery 63. That is, the planar base wall portion 67 extends substantially perpendicular to a pair of substantially parallel sidewall portions of the periphery 63.
The backstop 65 has a wall thickness “T_4B.” As described above with respect to the backstop 64, the wall thickness T_4Bof the backstop 65 is in a range between and including about two (2) times the wall thickness T₃and about three (3) times the wall thickness T₃of the sheath 62.
Furthermore, like the backstop 64 above, the backstop 65 may be coupled to the sheath 62 via a permanent coupling method including, for example, and without limitation, an adhesive bond, a weld joint (e.g., spin welding, ultrasonic welding, laser welding, or heat staking), and the like. Alternatively, the backstop 65 and the sheath 62 may be coupled together using any connection technique that enables the LSC 60 to function as described herein. The explosive material 25 may then be packed into the cavity of the sheath, such as the cavity 40 described above, to form the LSC.
Linear Shaped Charge Sheath with Plug Backstop
FIG. 7 is a rear perspective, partial exploded view drawing of an alternative LSC 70. In this embodiment, a sheath 72 is fabricated substantially similar to the sheath 22 described above. However, in the illustrated embodiment, a backstop 74 is fabricated as a separate component and is coupled to the sheath 72. In the exemplary embodiment, the sheath 72 has a periphery 76 (which is substantially the same size and shape as the peripheral wall 23, described above) defining an outer boundary of the sheath 72. A wall 79 of the sheath 72 has a substantially continuous wall thickness “Ts.”
The backstop 74 has a periphery 78 that is sized and shaped to fit within an end of the sheath 72. That is, the periphery 78 has substantially the same size and shape as a wall inner surface of the wall 79. The periphery 78 is complementary to the wall inner surface to facilitate forming a seal between the sheath 72 and the backstop 74. The backstop 74 has a wall thickness “T₆.” As described above with respect to the LSC 20, the wall thickness T₆of the backstop 74 is in a range between and including about two (2) times the wall thickness Ts and about three (3) times the wall thickness Ts.
The backstop 74 may be coupled to the sheath 72 via an interference fit with or without an adhesive disposed between the periphery 78 of the backstop 74 and the sheath 72. As used herein, the phrase “interference fit” means a value of tightness between the backstop 74 and the sheath 72, i.e., an amount of clearance between the components. A negative amount of clearance is commonly referred to as a press fit, where the magnitude of interference determines whether the fit is a light interference fit or interference fit. A small amount of positive clearance is referred to as a loose, slip, or sliding fit. Alternatively, the backstop 74 may be coupled to the sheath 72 using any suitable fastening technique that enables the LSC 70 to function as described herein. For example, the backstop 74 may be coupled to the sheath 72 via a permanent coupling method including, for example, and without limitation, a weld joint (e.g., spin welding, ultrasonic welding, laser welding, or heat staking).
Linear Shaped Charge Sheath with Fixed Cap Backstop
FIG. 8 is a rear perspective of an alternative LSC 80. FIG. 9 is a rear perspective, partial exploded view drawing of the alternative LSC 80. In this embodiment, a sheath 82 is fabricated substantially similar to the sheath 22 described above. However, in the illustrated embodiment, a cap backstop 84 is fabricated as a separate component and is coupled to the sheath 82. In the exemplary embodiment, the sheath 82 has a periphery 86 (which is substantially the same size and shape as the peripheral wall 23, described above) defining an outer boundary of the sheath 82. A wall 88 of the sheath 82 has a substantially continuous wall thickness “T₇.”
FIG. 10 is a front perspective of the cap backstop 84. FIG. 11 is a front view of the cap backstop 84. FIG. 12 is a side section view of the cap backstop 84, taken about line 12-12 shown in FIG. 11. The cap backstop 84 has a peripheral wall 90 that extends longitudinally to a backstop wall 92 (broadly, an end wall) a predetermined distance “D₁.” In the exemplary embodiment, the backstop wall 92 has an inner inverted “V” shaped portion 106 that corresponds to an outer edge of the inner legs of the sheath 82.
In the depicted example, the peripheral wall 90 has a substantially continuous wall thickness “T₈,” which is the same as the wall thickness “T₇” of the sheath wall 88. The backstop wall 92 has a substantially continuous wall thickness “T₉.” As described above with respect to the LSC 20, the wall thickness T₉of the backstop wall 92 is in a range between and including about two (2) times the wall thickness T₇and about three (3) times the wall thickness T₇.
The peripheral wall 90 is substantially symmetrical about a centerline “℄,” defined by line 12-12, shown in FIG. 11. More particularly, the peripheral wall 90 includes four (4) sides: sidewalls 120 and 122; and upper walls 124 and 126, which cooperate to define an inner periphery 94, which is complementary to a portion of the periphery 86 of the sheath 82. In an example, the intersection of each pair of adjacent sides (e.g., intersection of 120 and 124, 124 and 126, and 126 and 122) defines a smooth radiused transition. This facilitates manufacturing the cap backstop 84 by reducing cracking and/or breaking along the intersection of the sides. In certain other embodiments, for example, cap backstops fabricated by additive manufacturing techniques, the intersection of each pair of adjacent sides need not include a smooth radiused transition.
Further, the sidewalls 120 and 122 include inward projecting lips 128 and 130, respectively. The lips 128 and 130 project inward a predefined distance “D₂.” As described above, the peripheral wall 90 has a substantially continuous wall thickness T₈. In the depicted embodiment, the predefined distance D₂is less than or equal to the wall thickness T₈. The lips 128 and 130 facilitate coupling the cap backstop 84 to the sheath 82 without extending any portion of the peripheral wall 90 across the area of the inverted V-shaped portion of the sheath 82. The peripheral wall 90 defines an inner peripheral surface 96 that may abut, in substantial face-to-face contact, a portion peripheral surface of the sheath 82 when the cap backstop 84 is coupled to and end of the sheath 82, as depicted in FIG. 8.
The cap backstop 84 may be coupled to the sheath 82 via an interference fit and an adhesive disposed between the periphery 86 of the sheath and the peripheral surface 96 of the cap backstop 84. Alternatively, the cap backstop 84 may be coupled to the sheath 82 using any suitable fastening technique that enables the LSC 80 to function as described herein. For example, the cap backstop 84 may be coupled to the sheath 82 via a permanent coupling method including, for example, and without limitation, a weld joint (e.g., spin welding, ultrasonic welding, laser welding, or heat staking).
Linear Shaped Charge Sheath with Fixed Cap Backstop
FIG. 13 is a front perspective of an alternative cap backstop 100. FIG. 14 is a front view of the cap backstop 100. FIG. 15 is a side section view of the cap backstop 100, taken about line 14-14 shown in FIG. 14. In this example, the cap backstop 100 has a peripheral wall 102 that extends longitudinally to a backstop wall 104 a predetermined distance “D₃.” In the depicted example, the peripheral wall 102 has a substantially continuous wall thickness “T₁₀,” which is the same as the wall thickness “T₇” of the wall 88 of the sheath 82. The backstop wall 104 has a substantially continuous wall thickness “T₁₁.” As described above with respect to the LSC 20, the wall thickness T₁₁of the backstop wall 104 is in a range between and including about two (2) times the wall thickness T₇and about three (3) times the wall thickness T₇.
In the example embodiment, the cap backstop 100 is substantially similar to the cap backstop 84, except that the backstop wall 104 omits the inner inverted “V” shaped portion 106, as illustrated in FIG. 12. Rather, the depicted cap backstop 100 includes a substantially planar base wall portion 108 of the backstop wall 104. That is, the planar base wall portion 108 extends substantially perpendicular to a pair of substantially parallel sidewall portions 110 and 112 of the peripheral wall 102. The peripheral wall 102 also includes two (2) upper wall portions 114 and 116 that continue from the sidewall portions 110 and 112 to define the peripheral wall 102.
Further, sidewall portions 110 and 112 include inward projecting lips 132 and 134, respectively. The lips 132 and 134 project inward a predefined distance “D₄.” As described above, the peripheral wall 102 has a substantially continuous wall thickness T₁₀. In the depicted embodiment, the predefined distance D₄is less than or equal to the wall thickness T₁₀. The lips 132 and 134 facilitate coupling the cap backstop 100 to the sheath 82 without extending any portion of the peripheral wall 102 across the area of the inverted V-shaped portion of the sheath 82.
The sidewall portions 110 and 112 and the upper wall portions 114 and 116 of the peripheral wall 102 define an inner peripheral surface 118 that has substantially the same size and shape as at least a complementary portion of the periphery 86 of the sheath 82. Accordingly, the inner peripheral surface 118 may abut, in substantial face-to-face contact, at least the complementary portion of the peripheral surface of the sheath 82 when the cap backstop 100 is coupled to and end of the sheath 82.
The cap backstop 100 may be coupled to the sheath 82 via an interference fit and an adhesive disposed between the periphery 86 of the sheath and the inner peripheral surface 118 of the cap backstop 100. Alternatively, the cap backstop 100 may be coupled to the sheath 82 using any suitable fastening technique that enables the LSC 80 to function as described herein. For example, the cap backstop 100 may be coupled to the sheath 82 via a permanent coupling method including, for example, and without limitation, a weld joint (e.g., spin welding, ultrasonic welding, laser welding, or heat staking).
Advantageously, embodiments of the present invention provide a liner shaped charge (LSC) with a backstop having a wall thickness of about two (2) to three (3) times the wall thickness the sheath of the LSC. The backstop of this thickness substantially eliminates the run-down of a cut profile of the LSC. The backstop LSC provided by this disclosure increases the detonation efficiency of the LSC and decreases operating costs. Operators may no longer need to specify an LSC length greater than a length of the target in order to sufficiently cut the target.
Although the above description presents features of preferred embodiments of the present invention, other preferred embodiments may also be created in keeping with the principles of the invention. Such other preferred embodiments may, for instance, be provided with features drawn from one or more of the embodiments described above. Yet further, such other preferred embodiments may include features from multiple embodiments described above, particularly where such features are compatible for use together despite having been presented independently as part of separate embodiments in the above description.
Those of ordinary skill in the art will appreciate that any suitable combination of the previously described embodiments may be made without departing from the spirit of the present invention.
The preferred forms of the invention described above are to be used as illustration only and should not be utilized in a limiting sense in interpreting the scope of the present invention. Obvious modifications to the exemplary embodiments, as hereinabove set forth, could be readily made by those skilled in the art without departing from the spirit of the present invention.

Claims

1. A linear shaped charge comprising:

a sheath having a peripheral wall extending longitudinally a predetermined length, the sheath including an open end and an opposite closed end, the closed end defined by an end wall, the peripheral wall having a first wall thickness and the end wall having a second wall thickness, the second wall thickness being equal to or greater than the first wall thickness, the peripheral wall and the end wall defining a cavity; and

an explosive material located within and substantially filling the cavity.

2. The linear shaped charge in accordance with claim 1,

the second wall thickness being equal to or greater than the first wall thickness.

3. The linear shaped charge in accordance with claim 1,

the second wall thickness being equal to or greater than two (2) times the first wall thickness.

4. The linear shaped charge in accordance with claim 1,

the second wall thickness being in a range between and including about two (2) times the first wall thickness and about three (3) times the first wall thickness.

5. The linear shaped charge in accordance with claim 1,

the sheath comprising a unitary component fabricated via an additive manufacturing process.

6. The linear shaped charge in accordance with claim 5,

the additive manufacturing process including one or more of the following: direct metal laser melting (DMLM), direct metal laser sintering (DMLS), selective laser sintering (SLS), selective laser melting (SLM), and electron beam melting (EBM).

7. The linear shaped charge in accordance with claim 1,

the peripheral wall defining a first periphery of the sheath,

the end wall having a second periphery, the second periphery being substantially the same size and shape as the first periphery,

the end wall coupled to the sheath via one of the following: an adhesive bond and a weld joint, to define the closed end.

8. The linear shaped charge in accordance with claim 1,

the peripheral wall defining a wall inner surface of the sheath,

the end wall having a second periphery, the second periphery being substantially the same size and shape as the wall inner surface,

the end wall coupled to the sheath via an interference fit.

9. The linear shaped charge in accordance with claim 8,

the end wall coupled to the sheath via an interference fit and an adhesive disposed between the second periphery and the wall inner surface.

10. The linear shaped charge in accordance with claim 1,

the peripheral wall defining a periphery of the sheath,

the end wall comprising a backstop wall and a backstop peripheral wall that extends longitudinally from the backstop wall, the backstop peripheral wall defining an inner backstop peripheral surface, at least a portion of the inner backstop peripheral surface being substantially the same size and shape as at least a portion of the periphery of the sheath,

the end wall coupled to the sheath such that the least a portion of the backstop inner peripheral surface is in substantial face-to-face contact with the at least a portion of the periphery of the sheath.

11. The linear shaped charge in accordance with claim 10,

the end wall coupled to the sheath via an interference fit.

12. The linear shaped charge in accordance with claim 11,

the end wall coupled to the sheath via an interference fit and an adhesive disposed between the inner peripheral surface and the peripheral wall of the sheath.

13. The linear shaped charge in accordance with claim 10,

the end wall coupled to the sheath via one of the following: an adhesive bond, a slip fit with an adhesive, and a weld joint.

14. The linear shaped charge in accordance with claim 1,

the end wall comprising a substantially planar base wall portion that extends substantially perpendicular to a pair of parallel sidewall portions.

15. The linear shaped charge in accordance with claim 1,

the peripheral wall defining a V-shaped cross sectional shape of the sheath.

16. The linear shaped charge in accordance with claim 15,

the V-shaped cross sectional shape being substantially symmetrical about a centerline, the peripheral wall including six (6) sides, including a symmetrical pair of inner legs, a symmetrical pair of sidewalls, and a symmetrical pair of upper walls.

17. A method comprising:

fabricating a sheath of a linear shaped charge, the sheath comprising a peripheral wall including an open end and an opposite closed end, the closed end defined by an end wall, the peripheral wall having a first wall thickness and the end wall having a second wall thickness, the second wall thickness being equal to or greater than the first wall thickness, the peripheral wall and the end wall defining a cavity; and

filling the cavity with an explosive material.

18. The method in accordance with claim 17,

the operation of fabricating the sheath comprises forming the second wall thickness in a range between and including about two (2) times the first wall thickness and about three (3) times the first wall thickness.

19. The method in accordance with claim 17,

the operation of fabricating the sheath comprises melting and solidifying particles of a powdered material.

20. The method in accordance with claim 19,

the operation of melting and solidifying being performed via one of the following processes: direct metal laser melting (DMLM), direct metal laser sintering (DMLS), selective laser sintering (SLS), selective laser melting (SLM), and electron beam melting (EBM).