Patent Grant
11879711
The invention described herein was made in the performance of official duties by employees of the U.S. Department of the Navy and may be manufactured, used, or licensed by or for the Government of the United States for any governmental purpose without payment of any royalties thereon.
The present invention relates to tools for handling explosive cutting charges, and, in particular, to a container for use above and below water to produce radial cuts in-between radial structural components.
Existing methods to produce underwater cutting rely on straight, linear cuts or axis-symmetric conical shaped charges that are rigid. These may not fit in-between structures or produce a radial cut perpendicular to a plane. Flexible linear charges exist that allow a flexible curve cut to be produced, but lack a means to attach to the target as well as an easy method to initiate the charge. Generally, underwater charges are pre-packed with explosives to provide a watertight fitment to allow the shaped charge jet to form; this can be disadvantageous to the EOD operator, as it requires logistical planning to transport and store a pre-filled charge as compared to an empty cavity container.
A container can be provided that is made from a 3D printed plastic (porous) plastic material, which is not watertight for underwater use. A blow-molded, air cavity is placed in between the bottom of the liner inside of the housing to create an air-gap for the explosive cutting jet to form as well as provide a standoff distance for the jet. The rigid curved cutting jet may have a hemi-spherical or V-shaped cross-section shaped in the radial dimensions needed. The housing is a clamshell design that allows the user to field-pack plastic explosives (e.g., C-4) into the top of the shell, place the liner, and place the airtight cavity in the bottom or other half of the clamshell enclosure.
According to an aspect of the invention, a radial cutting cavity container includes a housing that defines a chamber for a shaped explosive charge. The housing is configured to allow a user to pack explosives therein. An airtight cavity is attached to the housing. The airtight cavity defines a standoff distance for the shaped explosive charge and has a concave surface adapted to form an explosive cutting jet. A liner is located between the housing and the airtight cavity. A support stand is attached to the container to allow the container to be mounted on a surface for creating a radial cut normal to the surface.
According to an exemplary container for an explosive charge, the container includes a support stand and a housing attached to the support base. The housing is adapted to define a chamber for a shaped explosive charge. An air cavity is attached to the housing. The air cavity is adapted to create an air-gap for an explosive cutting jet to form and to define a standoff distance for the shaped explosive charge. A cavity liner is between the housing and the air cavity. The container is configured to allow a user to pack explosives into the housing cover.
According to an aspect of the invention, an explosive cutting cavity includes a housing having a first portion making up an air cavity and a second portion cooperating with the first portion to form a clamshell enclosure. A liner is situated between the first portion and the second portion. An explosive charge is packed in the second portion. The first portion is shaped with a cross-section to focus the explosive charge through the air cavity and to provide standoff distance for the explosive charge.
These and other objects, features and advantages of the present invention will become apparent upon reference to the following description of the exemplary embodiments and to the drawings, wherein corresponding reference characters indicate corresponding parts throughout the several views of the drawings and wherein:
Shaped explosive charges are designed to produce a focused shockwave of great penetrating power directed outwardly along the central axis of an outwardly divergent cavity in one face of the charge. The cavity is usually conical, frusto-conical, or sphero-conical shaped. The cavity cross-section parallel to the base may be circular but, in elongated shaped charges used for linear and curvilinear cutters, it will be rectangular or other elongate form. The explosive composition is usually disposed symmetrically with respect to the cavity axis. In use, the shaped charge is placed with the base of the cavity facing towards the target surface and at an optimum distance for maximum cutting effect. Usually, the cavity is lined with a metal material to enhance the penetrating power.
The housing of the shaped charge device generally extends beyond the base of the cavity of the explosive charge to provide the required standoff, and for underwater charges the cavity and standoff volume are sealed to exclude water. Thus, underwater shaped charge devices generally have a sealed charge casing divided into an explosive charge compartment and a standoff compartment separated by a cavity liner presenting a concave surface within the standoff compartment.
The Radial Rigid Underwater Between-structure Explosive Cutting Cavity (RRUBECC) Container concept enables an improved container for explosive cutting of metal elements underwater using shaped explosive charges and to the shaped explosive charge devices and casings used in the method.
Referring to
The first portion 106 is shaped with a cross-section to focus the explosive charge through the air cavity 109 and to provide standoff space for the explosive charge. The first portion 106 has a concave surface 117 adapted to form an explosive cutting jet when in use. The concave surface 117 can be hemi-spherical or V-shaped in cross-section.
A support stand 120 is attached to the housing 103 to allow the container 100 to be mounted on a surface for creating a radial cut normal to the surface. The support stand 120 is horizontally offset from the housing and includes a base 123. Magnets 126 may be embedded into the base 123 of the support stand 120 to allow easy attachment of the RRUBECC container 100 to magnetic (iron-based) surfaces.
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It is contemplated that the RRUBECC container 100 described herein can be manufactured of lightweight plastic and/or by 3D printing or other means now known or developed in the future. For example, some filaments that may be used for 3D printing include ABS (Acrylonitrile Butadiene Styrene) and Polylactic Acid, commonly known as PLA. When superior strength is needed, a carbon fiber-infused nylon filament may be used. The air cavity 109 may be blow-molded for underwater use. The air cavity 109 is placed in between the bottom of the liner 114 inside of the housing 103 to create an air-gap for the explosive cutting jet to form, as well as to provide a standoff distance for the cutting jet.
In use, a user can field-pack plastic explosives (e.g., C-4) into the top portion 111 of the container 100, which is curved to produce radial cuts in-between radial structural components. The liner 114 is placed in the container 103 between the upper portion 111 and the bottom portion 106. The airtight cavity is placed in the bottom portion 106 of the clamshell enclosure. A single blasting cap or detonation cord knot is inserted through the opening 129 built into the side of the upper portion 111 so the blasting cap or detonation cord knot engages the plastic explosive. The container 103 is placed on the surface of a structure where a cut is desired. When the charge is initiated, the shape of the bottom portion 106 and the shape of the liner 114 cooperate to form a cutting jet oriented normal to the surface.
In some cases, a metal liner may not be used. The user can field-pack approximately 40 grams of plastic explosives (e.g., C-4) into the top portion 111 of the container 100, which is curved. This configuration creates a curved shape to the explosive charge. The hollow air gap is located below the explosive. Upon initiation, a plasma jet may be created, which thermally erodes the desired material (target). The ratio of charge width and amount to the air gap length and width is ideal to create a plasma jet. In alternate cases, the user can field-pack a bulk charge explosives into the same location as the air gap, without a metal liner. In this manner, the explosive is in direct contact to the desired material, so that initiation of the explosive charge will break the desired material.
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The invention has been described with references to specific embodiments. While particular values, relationships, materials, and steps have been set forth for purposes of describing concepts of the invention, it will be appreciated by persons skilled in the art that numerous variations and/or modifications may be made to the invention as shown in the disclosed embodiments without departing from the spirit or scope of the basic concepts and operating principles of the invention as broadly described. It should be recognized that, in the light of the above teachings, those skilled in the art could modify those specifics without departing from the invention taught herein. Having now fully set forth certain embodiments and modifications of the concept underlying the present invention, various other embodiments as well as potential variations and modifications of the embodiments shown and described herein will obviously occur to those skilled in the art upon becoming familiar with such underlying concept. It is intended to include all such modifications, alternatives, and other embodiments insofar as they come within the scope of the appended claims or equivalents thereof. It should be understood, therefore, that the invention might be practiced otherwise than as specifically set forth herein. Consequently, the present embodiments are to be considered in all respects as illustrative and not restrictive.
The terminology used herein is for the purpose of describing particular systems and methods only and is not intended to be limiting of this disclosure. As used herein, the singular forms “a”, “an”, and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises”, “comprising”, “includes”, and/or “including”, when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. Further, the terms “automated” or “automatically” mean that once a process is started (by a machine or a user), one or more machines perform the process without further input from any user.
The corresponding structures, materials, acts, and equivalents of all means or step plus function elements in the claims below are intended to include any structure, material, or act for performing the function in combination with other claimed elements as specifically claimed. The descriptions of the various exemplary embodiments herein have been presented for purposes of illustration but are not intended to be exhaustive or limited to the embodiments disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The terminology used herein was chosen to best explain the principles of the embodiments, the practical application or technical improvement over technologies found in the marketplace, or to enable others of ordinary skill in the art to understand the embodiments disclosed herein.
For example, terms such as “right”, “left”, “vertical”, “horizontal”, “top”, “bottom”, “upper”, “lower”, “under”, “below”, “underlying”, “over”, “overlying”, “parallel”, “perpendicular”, etc., as used herein, are understood to be relative locations as they are oriented and illustrated in the drawings (unless otherwise indicated). Terms such as “touching”, “on”, “in direct contact”, “abutting”, “directly adjacent to”, etc., mean that at least one element physically contacts another element (without other elements separating the described elements).
Finally, any numerical parameters set forth in the specification and attached claims are approximations (for example, by using the term “about”) that may vary depending upon the desired properties sought to be obtained by the present invention. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of significant digits and by applying ordinary rounding.
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