Patent Application
20130199397
The present invention relates to penetrators and methods for their manufacture.
Penetrators are used as a weapon against airborne or land based targets. These penetrators can take the form of a metal cube, (e.g. ¼″×¼″×¼″), or an explosively formed penetrator with a 3-dimensional geometry. When explosively launched they can cause significant damage by penetrating the outer surface or skin of a target such as an aircraft, missile, tank or other vehicle owing to their momentum. As such, it is preferable to make these penetrator cubes from a heavy metal. Historically, steel (7.85 gm/cc) has been used for these penetrators. However, heavier metals such as tantalum (Ta—16.3 g/cc) or depleted uranium (U—18.9 g/cc) are also of interest. The momentum of the high density projectile gives it outstanding properties as a penetrator.
A second type of penetrator depends on reactive energy release. After penetrating the skin of the target, a fragment of reactive material can react with oxygen to create a sustainable reaction. The latter produces both a fire start capability and overpressure within the target volume. Materials with sufficient reactivity include zirconium (6.3 g/cc), aluminum (2.7 g/cc), or magnesium (1.74 g/cc). However, the relatively low density of these materials makes them less suitable as kinetic energy penetrators.
Thus, there is a need for penetrators which combine both high density for purposes of penetration, as well as reactivity.
LaRocca in U.S. Pat. No. 4,807,795 describes a method for producing a bimetallic conoid. The method consists of first explosively bonding two metal disks and then shear-forming the bonded disks into a conoidal shape simultaneously over a mandrel. McCubbin in U.S. Pat. No. 5,567,908 describes a reactive case warhead comprised of magnesium, aluminum, zinc and zirconium that is made in such a manner as to maximize blast damage once the warhead penetrates the external shell of a target. The warhead employs a hardened steel front plate made in such a way to penetrate the walls of the target and that is specially shaped to insure a ripping or tearing of the exterior walls as the warhead enters. An end-loaded fuse ignites the explosive charge and reactive case at the proper time. Both of these prior patented inventions have inherent limitations, and are difficult to manufacture.
In our earlier. U.S. Provisional Application Ser. No. 60/729,533, filed Oct. 20, 2005, we describe a bimetallic layered penetrator of Zr/Ta/Zr produced by the plasma transferred arc solid free form fabrication (PTA SFFF) process. The resulting bimetallic layered penetrator was found to have sufficient mass and momentum to penetrate a target, and carry the reactive Zr into the target, resulting in considerably more damage than a non-reactive penetrator such as steel, and was particularly suited for manufacture of cube geometry penetrators. However, the presence of non-uniformities resulting from the layered bimetallic structure can cause difficulties in the explosive launch process.
Another type of bimetallic penetrator is a shaped penetrator which has a 3-dimensional geometry and is produced by the explosive forming process. However, the presence of possible non-uniformities resulting from the layered bimetallic structure also could cause difficulties in the explosive forming process.
The present invention overcomes the aforesaid and other disadvantages of the prior art. In accordance with the present invention we provide a penetrator formed of an alloy or composite of a high density metal and a reactive material; Unlike the bimetallic structures of the prior art, a penetrator made of a composite or an alloy has a uniform structure throughout. Thus, a penetrator formed, for example, of a high density metal and a reactive metal will have sufficient mass to penetrate steel plate, and upon striking the steel plate, provide a very substantial release of energy which would be seen to compare favorably to that obtained with a penetrator formed only of a high density metal or a penetrator formed only of a reactive metal, of the same size, launched at the same speed.
Further features and advantages of the present invention will be seen from the following detailed description, taken in conjunction with the accompanying drawings, wherein like numerals depict like parts, and wherein:
The present invention provides penetrators formed of a composite or an alloy of a high density metal and a reactive material.
As used herein the term “high density metal” means a metal having a density of greater than about 13.1 g/cc or about 817 lbs./cu feet. The term “reaction material” means a material that is capable of substantial energy release, e.g., through oxidation reaction.
The homogeneity of the a composite or alloy provides an extremely uniform structure which will facilitate the manufacture of shaped penetrators by the explosive forming process. Comparable uniformity and energy release can be obtained by utilizing a particulate composite manufactured using a powder of one metal and a molten metal of a second composition, e.g. Ta metal in a Zr matrix. Other heavy and/or reactive metals can be used in the manufacture of alloy and particulate composites in accordance with the present invention, e.g. an alloy of W as the heavy metal with Zr as the reactive metal. More than two metals can be used as well, e.g. ternary, quaternary and higher composition alloys and particulate composites. The alloys and particulate composites can be manufactured by any process that melts one or more of the metals. This can include, but is not limited to, the use of a plasma torch such as a welding torch, laser, furnace melting, arc melting, and induction and e-beam melting. Alternatively hot consolidation can be employed such as hot pressing in a die, hot isostatic pressing (HIP), and cold pressing followed by sintering below or above the melting point of one of the constituents such as the active metal zirconium.
As can be seen in the examples below if a Zr penetrator can penetrate the target structure, a very high level of reaction is obtained, which is desirable for weapon lethality. With a Ta/Zr alloy, the pressure buildup in the chamber, and the extent of reaction as indicated by residue after testing indicates the alloy composition is more effective than a pure Zr layer. It is believed that the increased pressure is the result of increased surface area in the alloy fragment after impact with the target when compared to the response of a pure Zr or the layered bimetallic penetration. Compared to pure Zr, a penetrator formed of Ta/Zr alloy would have a considerably higher mass density which would result in greater penetration capability than Zr alone.
Preferred as high density metals in accordance with the present invention are Ta, W, Re, Os, Ir, Pt, Au, U, and Hf, and an alloy thereof. Preferred as reactive materials in accordance with the present invention are reactive metals such as Zr, Mg, Al, Li, Be, Ti, Sc, V, H, Sr, Y, Si, Ge, and Nd, and an alloy thereof, or a rare earth metal and an alloy thereof, e.g., La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, En, Tm, Yb and Lu. Other reactive materials include hydrogen or carbon or a metal carbide.
The invention will be further demonstrated by the following non-limiting examples:
In this test, a steel cube with dimensions of ¼″ was gun launched at a speed of 5370 ft/sec and targeted at a steel encased test chamber. The experiment was instrumented with pressure transducers attached to the target chamber, an optical pyrometer to measure temperature, and a high speed digital camera to image the energy release. The cube penetrated the 0.060″ mild steel entrance plate, and then traversed the target chamber to a ¾″ rear plate. The energy release is shown in
In this test, a Ta cube with dimensions of ¼″ was gun launched at a speed of 5818 ft/sec and targeted at a steel encased test chamber. The experiment was instrumented with pressure transducers attached to the target chamber, an optical pyrometer to measure temperature, and a high speed digital camera to image the energy release. The cube penetrated the 0.060″ mild steel entrance plate, and then traversed the target chamber to a ¾″ rear plate. The energy release as noted by optical imaging is shown in
In this test, a Zr cube with dimensions of ¼″ was gun launched at a speed of 5297 ft/sec and targeted at a steel encased test chamber. The experiment was instrumented with pressure transducers attached to the target chamber, an optical pyrometer to measure temperature, and a high speed digital camera to image the energy release. The cube penetrated the 0.060″ mild steel entrance plate, and then traversed the target chamber to a ¾″ rear plate. The energy release as noted by optical imaging is shown in
An alloy of Ta and Zr was prepared by melting Zr and Ta metals in the arc of a plasma transferred arc (PTA) welding torch and depositing the product in a graphite crucible as shown in
A layered composite of Ta and Zr was prepared by depositing a layer of Zr on each side of a ⅛″ Ta plate at a torch amperage of 225 amps. After cooling to room temperature, the alloy was machined into cubes with a dimension of ¼″ by EDM machining. The molar ratio of the Ta and the Zr in the cubes was approximately 1.3Ta:1Zr. The cubes were gun launched at a speed of 6255 ft/sec and targeted at a steel encased test chamber. The experiment was instrumented with pressure transducers attached to the target chamber, an optical pyrometer to measure temperature, and a high speed digital camera to image the energy release. The cube penetrated the 0.060″ mild steel entrance plate, and then traversed the target chamber to a ¾″ rear plate. The energy release as noted by optical imaging is shown in
An alloy of W and Zr was prepared using the experimental setup as shown in
A particulate composite of Ta and Zr was prepared using the experimental setup as shown in
It should be understood that the preceding is merely a detailed description of certain preferred embodiments of this invention and that numerous changes can be made in accordance with the disclosure herein without departing from the spirit or scope of the invention. The following examples are to be viewed as illustrative of the present invention and should not be viewed as limiting the scope of the invention as defined by the appended claims.
This application is a divisional of U.S. patent application Ser. No. 11/764,036, filed Jun. 15, 2007, and claims priority from U.S. Provisional Application Ser. No. 60/805,124, and U.S. Provisional Application Ser. No. 60/805,128, both filed Jun. 19, 2006, the contents of which are incorporated hereby reference.
This invention was made in part with Government support under contract number FA8651-05-C-0103 awarded by the U.S. Air Force. The Government may have certain rights in the invention.
| Number | Date | Country | |
|---|---|---|---|
| 60805124 | Jun 2006 | US | |
| 60805128 | Jun 2006 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 11764036 | Jun 2007 | US |
| Child | 11764106 | US |
