Patent Application
20200408497
The present invention relates to a method for rendering safe unexploded military ordnance items using entrainment waterjet technology. A circular plug is cut out of the casing of the ordnance item and its internal material is washed-out and recovered.
According to US Environmental Protection Agency documents, unexploded ordnance (UXO), also sometimes referred to as unexploded “munitions”, at some domestic inactive military training ranges pose an “imminent and substantial” risk to the public. The cleanup of such ordnance is estimated to cost billions of dollars. Bringing unexploded munitions, over land, to a facility that has the capacity to demilitarized them using waterjet technology would be too hazardous because of the potential for unintended detonation.
In the past, unexploded ordnance was rendered safe (demilitarized) by detonating them, or by cutting them open and recovering the internal material. Unfortunately, such methods are considered either too dangerous, or environmentally unfriendly and are no longer allowed. Abrasive entrainment waterjet technology has the potential of providing a safe and environmentally acceptable way of rendering safe unexploded military ordnance.
Therefore, there is need in the art for a portable system, that can be transported virtually anywhere on land to a location where one or more unexploded pieces of military ordnance is located.
A method for rendering safe an unexploded military ordnance item, which method comprises:
a) providing: i) a source of compressed air, ii) a source of hydraulic power, iii) a system for delivering abrasive material to a high pressure waterjet cutting head , iv) a source of electrical power, v) a source of fresh water, vi) a control system; and vii) an apparatus for deploying a tool package containing a plurality of tools for accessing and recovering internal material from said ordnance item;
b) locating an unexploded military ordnance item to render safe;
c) lowering a tool package into place above said targeted military ordnance item, which tool package is comprised of an inverted U-shaped structure containing a low profile cylindrical bases having a circular base plate having an annular through-hole of a size that will allow each tool of said tool package to reach through said through-hole to perform its intended function on a targeted military ordnance item under said through-hole, which circular base plate is supported from above by two vertical legs, 180 degrees apart, which legs, at their opposite ends, are secured at opposite ends of a cross beam, which tool package contains a plurality of tools radially positioned about a moveable turntable wherein the tools of said tool package are positioned in an array about said turntable, and which turntable also contains an annular through-hole for each tool, which though-holes are of substantially the same size as the through-hole in said circular base plate, which tools including: i) a high pressure waterjet cutting head capable of cutting a plug of casing out of said ordnance item; ii) a plug removal tool having a head capable of grabbing said plug of casing material and extracting it for disposal; iii) a waterjet head having at least one jet capable of delivering an effective jet of water at a pressure capable of washing out at least a portion of any internal material from the interior of said military ordnance item, which tool package, at its bottom contains a curved ordnance item holding structure having a radius of curvature substantially that of the targeted military ordnance item;
d) maneuvering said tool package over the targeted ordnance item so that the ordnance item holding device is directly over the targeted ordnance item;
e) lowering the tool package so that the ordnance item holding device makes contact with and secures said ordnance item;
f) rotating the turntable until the high-pressure abrasive waterjet cutting head tool is aligned with the annular through-hole in both the turntable and said circular base plate;
g) lowering the abrasive cutting head through said annular through-hole in said base plate to the surface of the casing of said targeted ordnance item,
h) activating said abrasive waterjet cutting head and cutting a predetermined diameter plug out of the casing of said ordnance item;
i) deactivating said abrasive waterjet and raising the cutting head to its resting position;
j) rotating the turntable until the plug-removal tool is aligned with said annular through-hole of the circular base;
k) lowering said plug-removal tool through the annular through-hole and removing the plug, thereby exposing the internal material within the ordnance item casing;
l) raising the plug-removal tool to above said circular base;
m) rotating the turntable until the washout waterjet head is directly over the annular through-hole of the base plate; and
n) lowering the waterjet washout head into the interior of said ordnance item and activating the washout waterjet and washing out and recovering at least a portion of the internal material from the interior of said ordnance item.
It will be understood that the terms “ordnance item” and “military ordnance item” as used herein are used generically to mean any past or present military ordnance items that are typically dropped, or fired from a gun or cannon, although some may be self-propelled. Non-limiting examples of such military ordnance items include, projectiles, shells, bombs, missiles, rockets, as well as other munitions. For purposes of this invention the term “projectiles” is sometimes used for convenience to mean any unexploded military ordnance item that is capable of being rendered safe by the practice of the present invention. Such ordnance items are typically characterized as having a covering typically referred to as the casing which is most often comprised of a metallic material such as an iron-based material, a tin based material as well as a composite material. The casing encases a warfare material, non-limiting examples of which include energetic materials, chemical weapon materials, as well as bioweapon materials.
The key feature that may have to be changed to accommodate the difference size or shape of a particular ordnance item is the holding structure of the tool package that secures the ordnance item for processing. For example, bombs typically have a greater diameter than a conventional ordnance projectile shot from a gun or a cannon so such an item would require a holding device having a radius of curvature substantially the same as the bomb.
As previously stated, the instant invention is directed to the use of an abrasive waterjet cutting and accessing system comprising a tool package containing a plurality of tools capable of being useful for cutting into the casing of an unexploded military ordnance item and washing out and retrieving the internal material contained therein.
It is considered too dangerous to handle unexploded military ordnance, many of which are decades old and most likely in an advanced condition of decay. Thus, it is important that a totally unmanned system be used to render such item safe. All the systems and equipment of the present invention are remotely controlled.
The following services at needed in order to support the use of the tool package of the present invention:
a) A control system comprising the necessary hardware such as a PLC and other I/O used to control the complete system. The abrasive delivery system; the deployment system, and the tool package of the present invention require control of a variety of valves, sensors, instruments, and motors that interface with the control system. A human/machine interface, such as a computer, is used to control all equipment. In addition, some mechanical buttons, switches, and levers, will also be interfaced for additional control features.
b) A source of compressed air that is required for actuating valves and for delivering abrasive to the cutting head. An air compressor with ballast tank can be used for this purpose. The air compressor will require electrical power.
c) A source of hydraulic power is required for operating actuators and motors. An electric hydraulic pump is preferred for this purpose.
d) An abrasive delivery system. An abrasive media is used with the waterjet cutting head for cutting the casing of the targeted ordnance item. This abrasive is pneumatically conveyed to the cutting head (below water) via the use of an abrasive metering device that controls the abrasive flow rate. The abrasive originates from a pressurized abrasive hopper that keeps the abrasive metering device full of abrasive. As a result, both air and abrasive are sent to the cutting head. The abrasive metering device is controlled by the control system.
e) A source of electrical power is provided which is required by the control system, air compressor, hydraulic unit, deployment system, water source, high-pressure pump, and tool package. A fuel-supplied generator can be used to provide the required electrical power.
f) A source of clean water is provided, which is required by the high-pressure pump for the cleaning head, cutting head, and washout head. In addition, water is required for cooling the high-pressure pump. A tank of water can be used for this purpose or a reverse osmosis (RO) unit used to generate clean water as required. It will be understood that sea water, although not preferred, can also used. Part of this fresh water system will be an appropriately sized water storage tank located above water. Fresh process water can also be stored underwater in a suitable storage device
g) A high-pressure water-jet pump for generating high-pressure water for the cleaning head, cutting head, and washout head. A variety of pump options exist that are either directly driven, such as a reciprocating pump, or a hydraulically driven pump, such as an intensifier pump. The pump generates the desired flow rate (1-5 gpm) of high-pressure (˜60 ksi) of water.
h) A deployment system including equipment to lower the tool package above the targeted ordnance item. The deployment system includes a hoist as well as the equipment necessary to properly handle all flexible lines attached to the tool package. These lines include the abrasive feed line, air lines, hydraulic lines, high-pressure water lines, control cables, etc.
The tool package is described in more detail in
Cleaning apparatus 21 provides a clean surface on the casing of the ordnance item, if needed, to enhance accessing (cutting) and capturing material generated during cutting as well as capturing washed-out internal material inside the ordnance. The tool package is maneuvered over the targeted ordnance item such that the cleaning head is positioned over one end, typically the fuse, or blunt, end of the ordnance item. The cleaning head is individually lowered to a predetermined cleaning distance above the targeted ordnance item and the entire tool package is moved, in a predetermined pattern, down the length of the ordnance item thereby removing at least of portion, preferably all, of any contaminant, including bioencrustacean growth that may have formed on the ordnance item. Also, part of the cleaning apparatus is a high-pressure water-jet cone nozzle 26 to help generate the high-velocity spray capable of removing contaminants. When cleaning is complete, the high-pressure water is turned off, the cleaning head is retracted, and the tool package moved over and lowered onto said targeted ordnance item in such a way that the ordnance item holding means is mated with the targeted ordnance item.
Also shown in this
Collection of the washed-out internal material can be performed with the use of at least one pump, preferably with use of two pumps. One pump can be used for pulling liquid from a water storage tank through the ordnance item holding, or mating device and into a collection tank. The other pump can be used to pull liquid from the water storage tank through the volume between the bottom of the tool package and the turntable. This can also be pumped to a collection tank.
Waterjets are fast, flexible, reasonably precise, and have recently become relatively easy to use. They use the technology of high-pressure water being forced through a small hole (typically called the “orifice” or “jewel”) to concentrate an extreme amount of energy through a small area. The restriction of the small orifice converts the high-pressure water into a high-velocity waterjet. The inlet (process) water for a pure waterjet is typically pressurized between 20,000 psi (138 MPa) and 150,000 psi (414 MPa). This is forced through the orifice, which is typically about 0.007″ to 0.020″ in diameter (0.18 to 0.4 mm) The result is a very high-velocity, very thin jet of water traveling in excess of the speed of sound in air.
Abrasive slurry waterjet, also known as an abrasive suspension jet, typically uses a hopper filled with abrasive, water, and a slurrying or suspension agent. This combined mixture is then pressurized and forced through the orifice of the cutting head. An abrasive slurry waterjet system must maintain the abrasive in suspension. This is typically done by the use of chemical additives and/or mechanical means, in order to prevent the abrasive from dropping out of suspension in the piping which can result in plugging and disabling of the system. Likewise, the flow of a pressurized abrasive and water slurry mix is highly erosive to piping, valves, and fittings used in the system. In addition, one or more large pressure vessels should be used to contain a sufficient amount of abrasive slurry for cutting. Consequently, an abrasive slurry waterjet system is typically limited in pressure to approximately 140 MPa, and normally operates at pressures closer to about 70 MPa.
Non-limiting examples of abrasive materials that are suitable for use in the present invention include glass, silica, alumina, silicon carbide aluminum-based materials, garnet, as well as elemental metal and metal alloy slags and grits. Preferred are garnet and aluminum-based materials. It is also preferred that the abrasive particles have either sharp edges or that they be capable of fracturing into pieces having sharp cutting edges, such as for example, octahedron or dodecahedron shaped particles. The size of the abrasive particles may be any suitable effective size. By effective size, is meant a size that will not plug the cutting head and that will be effective for removing the material of which the targeted object to be cut is made from (typically a metal alloy, such a steel) and which is effective for forming a substantially homogeneous mixture with the fluid carrier. Useful particle sizes for the abrasive material will range from about 3 mm to 55 microns, preferably from about 15 mm to 105 microns, and most preferably from about 125 microns to about 250 microns.
Abrasive entrainment waterjets use a high velocity waterjet, formed by pressurized water passing through an orifice (jewel) of the cutting head resulting in a partial vacuum in a mixing chamber downstream of the orifice that aspirates and entrains abrasive particles that are introduced into the mixing chamber. Although transport and delivery of abrasive particles is typically performed by vacuum aspiration, the abrasive transport can also be performed by pneumatic conveyance, or by a fluid conveyance as an abrasive suspension.
Abrasive entrainment waterjet technology has several advantages over abrasive slurry waterjet technology. For example, it is more reliable; it requires less maintenance; it is able to operate at internal system pressures up to about 1,000 MPa or more; it can operate in a continuous mode rather than in a batch mode; it doesn't require expensive chemical additives; and it is able to operate with significantly lower abrasive consumption.
The type of waterjet cutting head that is preferred for the practice of the practice of the present invention will be an abrasive entrainment waterjet cutting head that is generally comprised of: a metal body having an outer cylindrical surface and a central bore substantially parallel to the cylindrical surface, with an upstream direction and a downstream direction. It will have a jewel orifice mounted in the bore in the metal body. A portion of the central bore will typically be downstream of the jewel forming a mixing chamber. An inclined bore for abrasive material passes from the outer cylindrical surface to the central bore, preferably at an incline and joining the central bore downstream of the jewel at the mixing chamber. There is also typically provided a nozzle wherein the waterjet containing the abrasive further mixes and exits.
As previously mentioned, any type of waterjet pump can be used in the practice of the present invention as long as it is capable of delivering a jet of water, with entrained abrasive material, at a pressure of at least about 280 MPa to about 1000 MPa. A referred type of waterjet pumps suitable for use in the present invention is an intensifier pump. Waterjet intensifier pumps are well known in the art and utilize the so-called “intensification” principle. A waterjet intensifier pump typically operates by having pressurized hydraulic oil flow into one side of a centrally located hydraulic piston having double ended piston rods extending into the high pressure water cylinders at each end. The central hydraulic piston of the intensifier pump is typically 20 times the area of each piston rod giving a 20:1 intensification ratio. The piston rods, in turn, form the high pressure water pistons. Consequently, an application of 14 MPa hydraulic oil to the central hydraulic piston results in a twenty-fold intensification of pressure in the water cylinder and yields an outlet water pressure of 280 MPa. The outlet pressure of the water can be controlled by adjusting the inlet hydraulic oil pressure. When the centrally located hydraulic piston reaches the end of its stroke, a hydraulic valve body switches the flow of oil to the opposite side of the hydraulic piston and the process continues with the opposite water piston. The depressurized oil from the central cylinder is exhausted via the control valves to an exhaust port connected with an oil return to an oil reservoir.
| Number | Date | Country | |
|---|---|---|---|
| 62848158 | May 2019 | US |
