Lightweight armor plates with a ceramic component, systems including same and methods of use thereof

0001[0001] This application is a continuation in part of U.S. patent application Ser. No. 10/155,670 filed on May 28, 2002 and currently pending which claimed priority from U.S. patent application Ser. No. 60/343,213 filed on Dec. 31, 2001 and now abandoned.

FIELD AND BACKGROUND OF THE INVENTION

0002[0002] The present invention relates to lightweight armor plates with a ceramic component, systems including same and methods of use thereof and, more particularly, to an armor plate with a ceramic component which may be reversibly attached to protect a target from a projectile.

0003[0003] The recent increase in political unrest, financially motivated crime and/or terrorism in many areas of the world has caused many people to fear that they are potential targets for attack with firearms or explosive devices.

0004[0004] Typically, protection from bullets or shrapnel required use of expensive and heavy armor. True armored vehicles, such as tanks and other vehicles designed to withstand artillery shells and rockets are obviously ill suited to urban travel.

0005[0005] Previously available armor for normal vehicles was typically so heavy that it required use of very large motors and/or all wheel drive transmission systems. This meant that retrofitting a typical passenger vehicle with armor was virtually infeasible.

0006[0006] Further, the cost of typical armoring for a vehicle is prohibitive, owing in part to the types of materials employed and in part to the amount of armor employed.

0007[0007] These considerations also apply to armoring static targets such as buildings, windows and bus stops. Similarly, portable bulletproof protection has typically been limited to “flack jackets” and helmets which offer no protection for the face and often leave arms and legs unprotected.

0008[0008] There is thus a widely recognized need for, and it would be highly advantageous to have, lightweight armor plates with a ceramic component, systems including same and methods of use thereof devoid of the above limitations.

SUMMARY OF THE INVENTION

0009[0009] According to one aspect of the present invention there is provided a lightweight opaque armor plate. The plate includes:(a) a ceramic layer, the ceramic being designed and constructed to absorb and disperse energy from a projectile, and (b) a hardened metal layer, the hardened metal layer situated behind the ceramic layer and being designed and constructed to prevent penetration by the projectile. A total weight of the plate is less than approximately exactly 43 kg/M²of the plate.

0010[0010] According to one aspect of the present invention there is provided a system for protecting a target from impact by a projectile The system includes: (a) at least one lightweight opaque armor plate including: (i) a ceramic layer designed and constructed to absorb and disperse energy from a projectile, and (ii) a hardened metal layer situated behind the ceramic layer and designed and constructed to prevent penetration by the projectile; and (b) a positioning device designed and constructed to engage and retain the at least one lightweight armor plate in a position between the target and the projectile The total weight of the armor plate is less than approximately exactly 43 kg/M².

0011[0011] According to another additional aspect of the present invention there is provided a method of protecting a target from impact by a projectile. The method includes: (a) ascertaining at least one source from which a projectile is likely to emanate; and (b) employing a positioning device to engage and retain at least one lightweight opaque armor plate in a position between the target and the at least one source from which a projectile is likely to emanate; wherein the lightweight opaque armor plate includes: (i) a ceramic layer designed and constructed to absorb and disperse energy from a projectile, (ii) a hardened metal layer situated behind the ceramic layer and designed and constructed to prevent penetration by the projectile. The total weight of the plate is less than approximately exactly 43 kg/M².

0012[0012] According to further features in preferred embodiments of the invention described below, a total thickness of the hardened metal layer and the ceramic layer is in the range of approximately 12 to approximately 18 mm more preferably in the range of approximately 6 to approximately 12 mm.

0013[0013] According to still further features in the described preferred embodiments the hardened metal layer is constructed of a material selected from the group consisting of heat treated aluminum and a heat-treated alloy.

0014[0014] According to still further features in the described preferred embodiments the hardened metal layer contains at least one material selected from the group consisting of aluminum, magnesium, silicon, titanium, copper, manganese and chromium.

0015[0015] According to still further features in the described preferred embodiments the opaque plate further includes a reversible attachment device.

0016[0016] According to still further features in the described preferred embodiments the ceramic layer includes primarily at least one material material selected from the group consisting of Alumina (Al₂O₃) and Magnesia (MgO).

0017[0017] According to still further features in the described preferred embodiments the opaque plate further includes a coating.

0018[0018] According to still further features in the described preferred embodiments the system further includes at least one item selected from the group consisting of (c) a transparent armor plate including; (i) at least one glass layer placed to receive an initial impact from a projectile; (ii) at least one plastic layer, the plastic layer situated behind the glass layer and designed and constructed to be impenetrable by the projectile, the plastic layer includes at least approximately 50% of the total weight of the plate. (iii) at least one adhesive, the adhesive bonding two of the layers together; wherein a degree of transparency thereof permits visibility therethrough by a user thereof; and (d) an opaque armor plate including: (i) a first hardened metal layer, the first hardened metal layer placed to receive an initial impact from a projectile; (ii) a force dissipating layer, the force dissipating layer situated behind the first hardened metal layer and being designed and constructed to absorb and disperse energy from the projectile, (iii) a second hardened metal layer, the second hardened metal layer situated behind the force dissipating layer and being designed and constructed to prevent penetration by the projectile.

0019[0019] According to still further features in the described preferred embodiments the positioning device includes at least one item selected from the group consisting of a reversible attachment device, a permanent attachment device, a base and an article of clothing modified to accommodate the at least one lightweight armor plate.

0020[0020] According to still further features in the described preferred embodiments the method further includes providing at least one additional lightweight armor plate, wherein the additional lightweight armor plate includes at least one item selected from the group consisting of: (i) a transparent armor plate includes; (1) at least one glass layer placed to receive an initial impact from a projectile; (2) at least one plastic layer, the plastic layer situated behind the glass layer and designed and constructed to be impenetrable by the projectile, the plastic layer includes at least approximately 50% of the total weight of the plate. (3) at least one adhesive, the adhesive bonding two of the layers together; wherein a degree of transparency thereof permits visibility therethrough by a user thereof; and (ii) an opaque armor plate includes:(1) a first hardened metal layer, the first hardened metal layer placed to receive an initial impact from a projectile; (2) a force dissipating layer, the force dissipating layer situated behind the first hardened metal layer and being designed and constructed to absorb and disperse energy from the projectile, (3) a second hardened metal layer, the second hardened metal layer situated behind the force dissipating layer and being designed and constructed to prevent penetration by the projectile.

0021[0021] According to still further features in the described preferred embodiments employing a positioning device includes employing at least one item selected from the group consisting of a reversible attachment device, a permanent attachment device, a base and an article of clothing modified to accommodate the at least one lightweight armor plate.

0022[0022] The present invention successfully addresses the shortcomings of the presently known configurations by providing portable lightweight armor plates which includes only two layers, one of which is a ceramic layer, systems including the two layer plates and methods of use thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

0023[0023] The invention is herein described, by way of example only, with reference to the accompanying drawings. With specific reference now to the drawings in detail, it is stressed that the particulars shown are by way of example and for purposes of illustrative discussion of the preferred embodiments of the present invention only, and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the invention. In this regard, no attempt is made to show structural details of the invention in more detail than is necessary for a fundamental understanding of the invention, the description taken with the drawings making apparent to those skilled in the art how the several forms of the invention may be embodied in practice.

0024[0024] In the drawings:

0025[0025]FIG. 1 is a cross section of a lightweight transparent armor plate employed in some embodiments of the present invention;

0026[0026]FIG. 2 is a cross section of a lightweight opaque armor plate according various preferred embodiments of the present invention;

0027[0027]FIG. 3 is a perspective view of a reversible attachment device according to the present invention;

0028[0028]FIG. 4 is a perspective view of a carrying case for a portable armoring system;

0029[0029]FIG. 5 is a simplified flow diagram illustrating a sequence of steps in a method according to the present invention; and

0030[0030]FIG. 6 is a perspective view of a portable shelter constructed of armor plates according to the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

0031[0031] The present invention is of lightweight armor plates with a ceramic component systems including same and methods of use thereof which can be employed to protect a target from damage caused by projectiles including, but not limited to, bullets.

0032[0032] Specifically, the present invention can be used to armor a vehicle or a portion thereof. Alternately, or additionally, the present invention may be employed to protect a structure such as a building or bus stop, or a portion thereof such as a window or a door. Alternately, the present invention may be employed as a portable bulletproof shelter for one or more people. Alternately, the present invention may be employed in construction of improved bulletproof clothing.

0033[0033] The principles and operation of lightweight armor plates, systems including same and methods of use thereof according to the present invention may be better understood with reference to the drawings and accompanying descriptions.

0034[0034] Before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments or of being practiced or carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein is for the purpose of description and should not be regarded as limiting.

0035[0035] For purposes of this specification and the accompanying claims, the term “projectile” includes, but is not limited to, a bullet fired from a weapon such as, for example, an M-16, an AK-47 (i.e. Kalashnikov), a Galil assault rifle, an Uzi machine gun, a pistol, a rifle or similar. Projectile further includes a collection of small projectiles, for example buckshot fired from a shotgun shell or shrapnel from an explosive device. The following bullets are specifically included in the definition of projectile: AK-47 7.62×39AP; AK-47 7.62×51AP NATO; M16 5.56×45 33-109 and M-80 Ball 7.62×51.

0036[0036] For purposes of this specification and the accompanying claims, the term “explosive device” includes, but is not limited to, a hand grenade, a pipe bomb and an explosive packet worn or carried by a suicide bomber. Specifically, suicide bombers are known to include small metal pieces (e.g. screws, nails) within the explosive packet to produce shrapnel. These small metal pieces are included within the definition of projectile.

0037[0037] For purposes of this specification and the accompanying claims, the term “impenetrable” indicates a capability of preventing penetration by a projectile fired from a weapon at a distance of fifty meters, more preferably four to five meters, most preferably zero to one meter from the armor plate.

0038[0038] Referring now to the drawings, FIG. 2 depicts a lightweight opaque armor plate <b>40</b> including a ceramic layer <b>44</b>. Ceramic layer <b>44</b> is designed and constructed to absorb and disperse energy from a projectile <b>34</b>. Plate <b>40</b> further includes a hardened metal layer <b>46</b> situated behind ceramic layer <b>44</b> and designed and constructed to prevent penetration by projectile <b>34</b>. A total weight of plate <b>40</b> is less than approximately exactly 43 kg/M². Preferably, a total thickness of hardened metal layer <b>46</b> and ceramic layer <b>44</b> is in the range of approximately <b>12</b> to approximately 18 mm more preferably in the range of approximately 6 to approximately 12 mm. Preferably, hardened metal layer <b>46</b> is constructed of heat treated aluminum or a heat-treated alloy as described in more dtail hereinbelow. For example, hardened metal layer <b>46</b> maycontain materials including, but not limited to, aluminum, magnesium, silicon, titanium, copper, manganese and chromium.

0039[0039] Preferably opaque plate <b>40</b> further includes a reversible attachment device <b>38</b> and/or a coating <b>48</b> as described in more detail hereinbelow.

0040[0040] Preferably, ceramic layer <b>44</b> includes primarily Alumina (Al₂O₃), Magnesia (MgO) or a combination thereof. Preferably layer <b>44</b> is 96% Alumina, more preferably 98% Alumina, most preferably between 98% and Alumina.

0041[0041] The present invention is further embodied by a system for protecting a target from impact by a projectile. The system includes at least one lightweight opaque armor plate including <b>40</b> including a ceramic layer <b>44</b> and a hardened metal layer <b>46</b> as detailed hereinabove and a positioning device (e.g <b>38</b> or <b>60</b> as detailed hereinbelow) designed and constructed to engage and retain the at least one lightweight armor plate <b>40</b> in a position between the target and projectile <b>34</b>.

0042[0042] Preferably the system further includes a transparent armor plate <b>20</b> (FIG. 1) as detailed hereinbelow and /or an opaque armor plate <b>40</b> including a first hardened metal layer <b>42</b>, a force dissipating layer <b>44</b>, and a second hardened metal layer <b>46</b> as detailed hereinbelow.

0043[0043] The positioning device may be, for example, a reversible attachment device <b>38</b> or <b>60</b>, a permanent attachment device, a base or an article of clothing modified to accommodate plate <b>40</b>.

0044[0044] The present invention is further embodied by a method <b>100</b> (FIG. 5) protecting a target from impact by projectile <b>34</b>. Method <b>100</b> includes ascertaining <b>102</b> at least one source from which a projectile is likely to emanate and employing <b>104</b> a positioning device (e.g. <b>38</b> or <b>60</b>) to engage and retain at least one lightweight opaque armor plate <b>40</b> in a position between the target and the at least one source from which a projectile is likely to emanate. According to method <b>100</b>, the lightweight opaque armor plate <b>40</b> is as described hereinabove and includes a ceramic layer <b>44</b> and hardened metal layer <b>46</b>.

0045[0045] Preferably, method <b>100</b> further includes providing at least one additional lightweight armor plate, such as, for example transparent armor plate <b>20</b> as detailed hereinbelow and/or an opaque armor plate <b>40</b> including a first hardened metal layer <b>42</b>, a force dissipating layer <b>44</b>, and a second hardened metal layer <b>46</b> as detailed hereinbelow.

0046[0046] Preferably, employing a positioning device includes employing, for example, reversible attachment device <b>38</b>, a permanent attachment device <b>110</b>, a base <b>116</b> and an article of clothing <b>114</b> modified to accommodate the at least one lightweight armor plate (<b>20</b> or <b>40</b>).

0047[0047]FIG. 1 illustrates a lightweight transparent armor plate <b>20</b>. Plate <b>20</b> includes at least one glass layer <b>22</b> placed to receive an initial impact from a projectile <b>34</b> (pictured as an arrow) on an impact surface <b>36</b>. Plate <b>20</b> further includes at least one plastic layer <b>26</b> or <b>28</b> situated behind glass layer <b>22</b> and designed and constructed to be impenetrable by projectile <b>34</b> which is typically, but not always, a bullet fired from a gun at close range as detailed hereinabove. Plastic layer <b>26</b> or <b>28</b> constitutes at least approximately 50% of a total weight of plate <b>20</b>. Plate <b>20</b> further includes at least one adhesive <b>30</b> or <b>32</b>. Adhesive <b>30</b> or <b>32</b> bonds two of the layers of plate <b>20</b> together. Plate <b>20</b> is further designed and constructed so that a total weight of the plate is less than approximately exactly 50 kg/M². Preferably plate <b>20</b> is supplied in relatively small pieces so that a total weight of each piece does not exceed 20 kg, more preferably 15 kg, still more preferably 10 kg, most preferably 5 kg. The degree of transparency of the plate permits visibility therethrough by a user thereof. This means that plate <b>20</b> may be used as, for example, a face-shield of a helmet or a window of a building or a vehicle. Preferably, plate <b>20</b> is used in conjunction with an existing window, most preferably plate <b>20</b> is reversibly attachable to an existing window to render it bulletproof. For these purposes, larger plates <b>20</b> or <b>40</b> may be preferred, for example plates having dimensions of 1×2 M. Such large plates will weigh approximately 100 kilos and would potentially require two people to install. Alternately or additionally, a single person operating installation equipment might be employed.

0048[0048] Plate <b>20</b> preferably has a total thickness in the range of approximately 30 to approximately 40 mm. This includes the thickness of at least one glass layer <b>22</b> and <b>24</b>, the at least one plastic layer <b>26</b> and/or <b>28</b> and the at least one adhesive <b>30</b> and <b>32</b>.

0049[0049]FIG. 1 depicts a preferred embodiment of plate <b>20</b> which includes at least one glass layer composed of at least two glass layers <b>22</b> and <b>24</b>. In this preferred embodiment of plate <b>20</b>, at least one plastic layer <b>26</b> or <b>28</b> includes at least two plastic layers <b>26</b> and <b>28</b>. The plastic layer may be constructed of a material selected from the group consisting of an acrylic plastic (e.g. <b>26</b>) and polycarbonate (e.g. <b>28</b>). Each plastic layer <b>26</b> or <b>28</b> may optionally be constructed of a number of thinner sheets of plastic bonded together until a desired thickness is achieved.

0050[0050] Preferably plate <b>20</b> further includes a reversible attachment device <b>38</b>. For purposes of this specification and the accompanying claims, the phrase “reversible attachment device” includes, but is not limited to, at least one hook, at least one snap, at least one grommet, at least one cotter pin, Velcro™, at least one magnet, at least one suction cup, at least one button, at least one mounting bracket, at least one flexible strap, at least one engageable edge or combinations thereof Reversibility of attachment may be achieved, for example, by installing a first portion of a reversible attachment device at a desired point of attachment and a companion portion of the reversible attachment device on the armor plate. Alternately, a reversible attachment device <b>38</b> may be reversibly attachable to both plate <b>20</b> and a desired point of attachment as depicted in FIG. 3 of sling <b>60</b>. Reversible attachment device <b>38</b> in the form of sling <b>60</b> includes at least one pocket <b>62</b> designed and constructed to engage and retain plate <b>20</b>. Plate <b>20</b> may then be reversibly mounted, for example in a door of an automobile so that it covers a side window, by means of hooks <b>38</b> which slip over the doorframe surrounding the window. Preferably sling <b>60</b> includes additional pockets e.g. <b>64</b> and <b>66</b> attached by fasteners <b>70</b>. Pockets <b>64</b> and <b>66</b> may accommodate additional plates <b>20</b> or <b>40</b> (FIG. 2) to increase the area protected from projectile <b>34</b>. Sling <b>60</b> may be mounted either on an exterior side or anterior side of a surface such as a car door. Plates <b>20</b> and <b>40</b> will conform to the size of the specific car door, or, more preferably, to a generic car door dimension. Modifications in dimensions can easily produce slings <b>60</b> suited to a variety of purposes including protection of various windows in a vehicle and windows or doors of buildings.

0051[0051] Layers of plate <b>20</b> are preferably bonded one to another with at least one adhesive such as, for example, PVB <b>30</b> or polyurethane <b>32</b>. PVB <b>30</b> is typically supplied as thin sheets which are heat-sealed to, for example, two layers of glass <b>22</b> and <b>24</b> or a glass layer <b>24</b> and a plastic layer (e.g. <b>26</b> or <b>28</b>). Polyurethane <b>32</b> may be applied as, for example, a liquid glue to bond acrylic <b>26</b> and/or polycarbonate <b>28</b> layers to each other. Alternately, or additionally polyurethane <b>32</b> may be supplied as thin sheets which are heat-sealed to bond two layers.

0052[0052] The present invention is further embodied by a lightweight opaque armor plate <b>40</b> (FIG. 2). Plate <b>40</b> includes a first hardened metal layer <b>42</b>, placed to receive an initial impact from a projectile <b>34</b> on an impact surface <b>36</b>. Plate <b>40</b> further includes a force-dissipating layer, the force-dissipating layer <b>44</b> situated behind first hardened metal layer <b>42</b>. Force dissipating layer <b>44</b> is designed and constructed to absorb and disperse energy from projectile <b>34</b>. Force dissipating layer <b>44</b> may be constructed of a material such as, for example polyurethane, Keviar™, dynima, magnesium, aluminum, an acrylic plastic or iron. Plate <b>40</b> further includes a second hardened metal layer <b>46</b> situated behind force dissipating layer <b>44</b> and designed and constructed to prevent penetration by projectile <b>34</b>. Preferably, the total weight of plate <b>40</b> is less than approximately exactly 50 kg/M Preferably plate <b>40</b> is supplied in relatively small pieces so that a total weight of each piece does not exceed 20 kg, more preferably 15 kg, still more preferably 10 kg, most preferably 5 kg. Plate <b>40</b> may be used as, for example, a body shield, a portion of a helmet or a portable protective wall. Preferably, plate <b>40</b> is used in conjunction with an existing surface such as, for example, a car door. Most preferably plate <b>40</b> is reversibly attachable to an existing surface to render it bulletproof.

0053[0053] Preferably a total thickness of plate <b>40</b> is in the range of approximately 12 to approximately 18 mm in order tp provide protection from a rifle bullet. Thinner plates, for example 6 mm to 12 mm may be employed to provide protection from pistol bullets. These thicknesses include the thicknesses of first and second hardened metal layers (<b>42</b> and <b>46</b>) and force dissipating layer <b>44</b>. Preferably first and second hardened metal layers (<b>42</b> and <b>46</b>) are each constructed of, for example, heat-treated aluminum or a heat-treated alloy (e.g. aluminum alloy). Thus, layers <b>42</b> and <b>46</b> may be similar in composition or different in composition.

0054[0054] The heat-treated aluminum alloy may include, for example, magnesium, copper, silicon or combinations thereof. Thus, according different preferred embodiments of the invention, the first and second hardened metal layers <b>42</b> and <b>46</b> may each independently contain materials including, but not limited to aluminum, magnesium, silicon, titanium, copper, manganese and chromium.

0055[0055] Examples of alloys known to be useful in construction hardened metal layers <b>42</b> and <b>46</b> are provided in table 1. These compositions are provided as examples only and are not intended to limit the scope of the invention. One ordinarily skilled in the art of metallurgy will be able to adjust the exact composition of an alloy to slightly alter weight or elasticity by adding, for example, rare earth metals such as tungsten, molybdenum or beryllium according to guidelines set fort in metallurgy texts. Addition of small quantities of such metals to the alloy is within the scope of the present invention. <tables id="TABLE-US-00001" num="1"><table frame="none" colsep="0" rowsep="0"><tgroup align="left" colsep="0" rowsep="0" cols="1"><colspec colname="1" colwidth="217PT" align="center" /><thead><row><entry namest="1" nameend="1" align="center">TABLE 1</entry></row></thead><tbody valign="top"><row><entry /></row><row><entry namest="1" nameend="1" align="center" rowsep="1" /></row><row><entry>Alloys useful in construction of hardened metal layers</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="3"><colspec colname="OFFSET" colwidth="28PT" align="left" /><colspec colname="1" colwidth="119PT" align="left" /><colspec colname="2" colwidth="70PT" align="center" /><tbody valign="top"><row><entry /><entry>MATERIAL</entry><entry>WEIGHT PERCENTAGE</entry></row><row><entry /><entry namest="OFFSET" nameend="2" align="center" rowsep="1" /></row><row><entry /><entry>Magnesium (Mg)</entry><entry>0.3-3.0</entry></row><row><entry /><entry>Silicon (Si)</entry><entry>0.0-8.0</entry></row><row><entry /><entry>Titanium (Ti)</entry><entry>0.0-1.0</entry></row><row><entry /><entry>Copper (Cu)</entry><entry>0.0-5.0</entry></row><row><entry /><entry>Manganese (Mn)</entry><entry>0.0-1.0</entry></row><row><entry /><entry>Chromium (Cr)</entry><entry>0.0-5.0</entry></row><row><entry /><entry>Aluminum (Al)</entry><entry> 70.0-100.0</entry></row><row><entry /><entry namest="OFFSET" nameend="2" align="center" rowsep="1" /></row></tbody></tgroup></table></tables>

0056[0056] Thus, according to some preferred embodiments of the invention hardened metal layers <b>42</b> or <b>46</b> may include 0.45 to 0.6% magnesium; 6.7 to 7.5% silicon; approximately 0.2% titanium and aluminum, for example 91.7 to 92.65% aluminum.

0057[0057] According to alternate preferred embodiments of the invention hardened metal layers <b>42</b> or <b>46</b> may include 2.1 to 2.9% magnesium; 1.2 to 2% copper; approximately 0.3% manganese; 0.18 to 0.35% chromium and aluminum, for example 94.45 to 96.22% aluminum.

0058[0058] According to additional alternate preferred embodiments of the invention hardened metal layers <b>42</b> or <b>46</b> may include 1.2% to 1.8% magnesium; 3.8 to 4.9% copper; approximately 0.3 to 0.9% manganese; and aluminum, for example 92.4 to 94.7% aluminum.

0059[0059] According to further additional alternate preferred embodiments of the invention hardened metal layers <b>42</b> or <b>46</b> may include 0.8 to 1.2% magnesium; 0.15 to 0.4% copper; approximately 0.4 to 0.8% silicon; and aluminum, for example 97.6 to 98.65% aluminum.

0060[0060] Methods for preparation of alloys are well known in the art and detailed description of common methods may be found, for example, in “Principles of Metal Casting” (eds. Heine and Rosenthal, McGraw Hill Book Co.; 1955). and in “Symposium on Principles of Gating” published by the American Foundrymen's Society (1951) or in “Casting Aluminum” by C. W. Ammen (Tab Books Inc.;1985) or in “Metallurgy of Aluminum Alloys by M. van Lancker (Chapman and Hall Ltd.; 1967). Each of these texts is fully included herein by reference.

0061[0061] The term “heat treatment” or “heat treated” as used herein preferably refers to a process which includes precipitation hardening, tempering, solution treatment or combinations thereof. As used herein, the term “tempering” specifically includes rapid cooling, for example by immersion in a chilled water bath or ice and water slurry.

0062[0062] Thus, one method for preparation of a hardened metal alloy according to the present invention includes solution treatment followed by tempering in an ice/water bath followed by precipitation hardening. This process imparts previously unachieved properties to the resultant alloy, for example elongation of 11%.

0063[0063] Solution treatment may be accomplished, for example by heating the alloy (e.g. Aluminum alloy) to a temperature in excess of 500 degrees centigrade, more preferably 540 to 550 degrees centigrade, most preferably approximately 543 degrees centigrade a period of two to eighteen hours. The alloy is subsequently cooled to less than 60 degrees centigrade, more preferably 20 to 30 degrees centigrade by immersion in a liquid bath, for example an ice/water bath or chilled acetone/ethanol bath for four to ten seconds. This process imparts a “potential hardness” to the alloy.

0064[0064] Precipitation hardening may be accomplished by, for example, heating the alloy to a moderate temperature, preferably 150 to 170 degrees more preferably 155 to 165 degrees centigrade. Preferably, precipitation hardening is performed 24 hours or more after solution treatment.

0065[0065] These industrial processes are described in greater detail in American Standards MIL-A-21180 (casting); MIL-A-6088 (heat treatment) and MIL-ASTM-B26 ASTM-B26 (all published by the U.S. Government Printing office; 1971) which are fully incorporated herein by reference.

0066[0066] Preferably plate <b>40</b> further includes a reversible attachment device <b>38</b> as defined hereinabove. Thus, attachment device <b>38</b>may be, for example, sling <b>60</b> as pictured in FIG. 3 and described hereinabove. Alternately, but also preferably, attachment device <b>38</b> may take the form of suction cups as pictured in FIG. 2.

0067[0067] In order to facilitate ease of handling, plate <b>40</b> further includes a coating <b>48</b>. Coating <b>48</b> may be, for example, rubber, plastic or fabric. Preferably fabric coatings are bonded to plate <b>40</b> with a suitable adhesive.

0068[0068] The present invention is further embodied by a system for protecting a target from impact by a projectile <b>34</b>. The system includes at least one lightweight armor plate (e.g. <b>20</b> or <b>40</b>; as described hereinabove) and a positioning device (e.g. <b>60</b> or <b>38</b>) designed and constructed to engage and retain at least one lightweight armor plate <b>20</b> and/or <b>40</b> in a position between the target and projectile <b>34</b>. Preferably, a total weight of the armor plate is less than approximately exactly 50 kg/M², more preferably less than approximately exactly 43 kg/M²and the armor plate is supplied in lightweight easily handled pieces as described hereinabove.

0069[0069] Positioning device <b>60</b> may alternately be embodied by a reversible attachment device <b>38</b> as defined hereinabove, a permanent attachment device (e.g. screws, nails, rivets, cement or glue), a base and an article of clothing modified to accommodate the at least one lightweight armor plate.

0070[0070] A base may be, for example a polygonal solid with an opening designed to engage and retain at least a portion of an edge of plate <b>20</b> or <b>40</b>. Alternately, a base may be an assembly of legs, preferably collapsible legs.

0071[0071] An article of clothing modified to accommodate the at least one lightweight armor plate <b>20</b> or <b>40</b> may be produced, for example, by incorporating pockets designed to engage and retain plates <b>20</b> or <b>40</b> into, for example, the legs of a pair of trousers. Alternately, or additionally, plates <b>20</b> or <b>40</b> may be sown between layers of fabric when manufacturing a garment. The garment, in these cases, functions as reversible attachment device <b>38</b>.

0072[0072] Alternately, or additionally, the invention may take the form of a portable bulletproof shelter <b>58</b> as depicted in FIG. 6. Shelter <b>58</b> includes rigid supports <b>72</b> upon which pockets <b>62</b>, <b>64</b>, and <b>66</b> are arranged. Plates <b>20</b> and <b>40</b> are installed in pockets <b>62</b>, <b>64</b>, and <b>66</b>, Wheels <b>74</b> allow a user of shelter <b>58</b> to easily adjust the location and or position of shelter <b>58</b> during use. Transparent plate <b>20</b> allows visibility during use. Opaque plates <b>40</b> are employed in areas where visibility is not required. Reversible attachment devices <b>38</b> allow removal and insertion of plates <b>20</b> or <b>40</b>. This facilitates assembly. Shelter <b>58</b> is preferably supplied in one or more carrying cases <b>80</b> as depicted in FIG. 4.

0073[0073] The present invention is further embodied by a method <b>100</b> of protecting a target from impact by a projectile <b>34</b>. Method <b>100</b> includes ascertaining <b>102</b> at least one source from which a projectile <b>34</b> is likely to emanate and employing <b>104</b> a positioning device to engage and retain at least one lightweight armor plate (e.g. <b>20</b> or <b>40</b>) in a position between the target and the at least one source from which a projectile is likely to emanate.

0074[0074] Method <b>100</b> preferably further includes causing <b>106</b> a total weight of the armor plate to be less than approximately exactly 43 kg/M². This may be accomplished, for example providing <b>108</b> a transparent armor plate <b>20</b> as described hereinabove and or an opaque armor plate <b>40</b> as described hereinabove.

0075[0075] Employing <b>104</b> a positioning device may include employing, for example, a reversible <b>112</b> attachment device <b>38</b> as described hereinabove, a permanent <b>110</b> attachment device, a base (e.g. wheels <b>74</b> in FIG. 6) or an article of clothing <b>114</b> modified to accommodate the at least one lightweight armor plate.

0076[0076] As an illustrative, non-limiting, example of use of the armored plates, system and method of the present invention, the following story of a telephone repairman is provided. The repairman typically drives his repair truck within the city limits of Utopia, where no shooting has occurred in recent memory. However, the outlying suburb of Chaos is within his service area and, occasionally he must travel north along a highway which passes past the village of Hades. Inhabitants of Hades habitually shoot at vehicles passing their village on the highway.

0077[0077] The repairman uses one of twenty repair trucks in the fleet of the telephone company. Each day he is assigned an available vehicle when he reports to work. The phone company has equipped all twenty vehicles with reversible attachment devices <b>38</b> in the form of metal snaps. The cost of installing snaps on all twenty vehicles was negligible compared to the cost of a single workmen's compensation lawsuit from an employee injured or killed by gunfire. Snaps are installed on the interior of the driver side door, the interior of the passenger side door and the interior of the frame surrounding the front windscreen and the midline of the ceiling over the front seat.

0078[0078] One day, the repairman reports for work and sees that he has a repair call in Chaos on his list of stops. Before beginning his daily rounds he stops at the dispatcher's office and requests one of three armoring kits purchased by the phone company to serve their twenty vehicles. The kit includes two suitcases <b>80</b> (FIG. 4), each of which is equipped with a handle <b>82</b> and a closure means (e.g. zipper <b>79</b>). One suitcase contains a sling <b>60</b> with a small transparent armored plate <b>20</b> and two opaque armored plates <b>40</b>. The total weight of this case, including contents is about 20 kilos. The second case contains a transparent plate <b>20</b>, designed to cover a third, more preferably a half, of the front windscreen of the repair truck and weighing 10-30 kilos, more preferably 11-16 kilos. The repairman loads the two cases into the back of his truck.

0079[0079] As he approaches the city limits of Utopia, he stops the truck and assembles the armor system. Assembly and mounting is accomplished quickly, preferably in less than 2 minutes, more preferably in approximately 1 minute or less. He first mounts sling <b>60</b> on the interior of the driver side door. He then inserts a transparent plate <b>20</b> into pocket <b>62</b> of sling <b>60</b> and two opaque plates <b>40</b> into pockets <b>64</b> and <b>66</b> of sling <b>60</b>. An additional transparent plate <b>20</b> is affixed to snaps on the interior frame of the front windscreen so that the left (driver's) side of the front windscreen is armored. The repairmen has chosen to employ <b>104</b> this configuration of positioning devices for plates <b>20</b> and <b>40</b> because he has ascertained <b>102</b> that projectiles <b>34</b> are most likely to emanate from Hades, which will be on his left as he travels north from Utopia to Chaos. The repairman travels without incident to Chaos.

0080[0080] Prior to returning to Utopia, the repairman moves sling <b>60</b> so that it hangs from snaps along the midline of the cabin interior. This positioning <b>104</b> is chosen because Hades will be on his right side as he travels south from Chaos to Utopia. Plate <b>20</b> on the front windscreen is not moved for the return trip. On his return trip, a sniper crouching in bushes three meters from the highway opens fire on the repair truck with an automatic rifle. Four projectiles <b>34</b> hit the repair truck. The first projectile <b>34</b> hits the left side of the front windscreen where it is stopped by plate <b>20</b> installed there, the second projectile <b>34</b> hits the right side of the front windscreen and then plate <b>40</b> in sling <b>60</b> hanging in the center of the passenger cabin. The third projectile hits the right front window of the truck and is similarly stopped by plate <b>40</b> in sling <b>60</b> hanging in the center of the passenger cabin. The fourth projectile hits the rear portion of the right side of the truck and passes through the truck behind the driver.

0081[0081] The glass layer <b>22</b> of plate <b>20</b> installed in the front windscreen is preferably replaced as it is cracked from the impact of the first projectile. Similarly, the front windscreen and front passenger side window of the truck are preferably replaced. However, the repairman has not been injured by projectiles <b>34</b> or glass shrapnel.

0082[0082] It will be appreciated that, if the repairman lived in Chaos, he could use the same armoring kit (plates <b>20</b> and <b>40</b>, sling <b>60</b> and cases <b>80</b>, for his own car and for his repair truck provided that reversible attachment devices are available in both vehicles. Alternately, or additionally, if the repairman visited Chaos frequently, he might choose to leave one or more components of the armioring kit installed all the time, instead of assembling and mounting them for specific trips.

0083[0083] Alternately, or additionally, two people traveling in the same vehicle could combine two kits to armor the full front windscreen and both front doors. Additional armoring kits could add protection to additional portions of a vehicle since the system of the present invention is fully modular.

0084[0084] Although the invention has been described in conjunction with specific embodiments thereof, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art. Accordingly, it is intended to embrace all such alternatives, modifications and variations that fall within the spirit and broad scope of the appended claims.