Frangible projectile and method of manufacture

FIELD OF THE INVENTION

0001This invention pertains generally to a low ricochet, non-toxic projectile, such as an air gun or slingshot projectile, that can be attracted and retained by a magnet, and a method of manufacturing the same.

BACKGROUND

0002It is desirable to manufacture low ricochet, non-toxic projectiles, such as air gun or slingshot projectiles, that break apart into small pieces when striking a hard surface, such as a rock, a steel plate or a concrete wall upon impact. For example, air gun projectiles must have enough integrity in their composition that they will not materially deteriorate or break part while passing through the barrel of an air gun or its magazine. It is also desirable for low ricochet, non-toxic air gun projectiles to have the capability of being attracted and retained by a magnet in order to function in air guns that depend upon a magnet to hold the projectile in position prior to firing.

0003Currently, many projectiles, such as BBs, are made of steel, iron or lead. The steel or iron projectiles tend to ricochet when striking a hard surface which can be dangerous, and lead projectiles do not function in air guns that use a magnet to keep the projectile in place prior to firing. Lead projectiles may also expose the shooter or others to high levels of lead if the shooting area is not properly ventilated or maintained. Further, lead poisoning may result if a young shooter, pet or other animal were to place a lead BB in their mouth or otherwise ingest the same, as they are known to do.

0004Consequently, there exists a long felt need in the art for a low ricochet, non-toxic projectile that can be attracted and retained by a magnet until fired. There is also a long felt need in the art for a projectile that breaks apart into small pieces or fragments when striking a hard surface such as a rock, a steel plate or a concrete wall upon impact. Finally, there is a long felt need in the art for a frangible, low ricochet projectile that accomplishes all of the forgoing objectives, is lead-free, and that is relatively inexpensive to manufacture and safe and easy to use.

SUMMARY

0005The following presents a simplified summary in order to provide a basic understanding of some aspects of the disclosed innovation. This summary is not an extensive overview, and it is not intended to identify key/critical elements or to delineate the scope thereof. Its sole purpose is to present some concepts in a simplified form as a prelude to the more detailed description that is presented later.

0006The subject matter disclosed and claimed herein, in one aspect thereof, comprises a low ricochet, non-toxic air gun or slingshot projectile that is capable of being attracted and retained by a magnet and that is comprised of a plurality of particles that are attracted by said magnet and one or more of the following: (a) a plurality of metal particles that are not attracted by said magnet; (b) an elastomer; (c) an elastomer adhesive; (d) a polymer; (e) an organic material; and (f) an inorganic material.

0007Also disclosed herein is a method for manufacturing a lead free, frangible air gun projectile comprising the steps of: (a) blending a plurality of metal particles with a flow agent to form a homogenous mixture; and (b) placing said homogenous mixture in a die. In a further preferred embodiment of the present invention, the method may further comprise one or more of the following steps of (c) swaging the homogenous mixture in said die with a punch to form said air gun projectile; (d) sintering the air gun projectile; and (e) tumbling the air gun projectile.

0008In accordance with an embodiment of the invention there is provided a projectile that is capable of being attracted and retained by a magnet and that is comprised of a plurality of particles that are attracted by said magnet.

0009Said plurality of particles may be mixed with a plurality of metal particles that are not attracted by a magnet.

0010Said plurality of particles may be mixed with an elastomer.

0011Said plurality of particles may be mixed with a polymer.

0012Said plurality of particles may be mixed with an organic material.

0013Said plurality of particles may be mixed with an inorganic material.

0014In accordance with another embodiment of the invention there is provided a low ricochet, non-toxic projectile that is capable of being attracted and retained by a magnet and that is comprised of a plurality of particles that are attracted by said magnet and one or more of the following: <ul id="ul0001" list-style="none" compact="compact"><li>a plurality of metal particles that are not attracted by a magnet;</li><li>an elastomer;</li><li>an elastomer adhesive;</li><li>a polymer;</li><li>an organic material; and</li><li>an inorganic material.</li></ul>

0015Said elastomer may be silicone.

0016Said polymer may be latex.

0017The projectile may further comprise a belly band.

0018The projectile may further comprise at least one fracture in an outer surface of said projectile.

0019In accordance with another embodiment of the invention there is provided a method for manufacturing a projectile comprising the steps of: <ul id="ul0002" list-style="none" compact="compact"><li>blending a plurality of metal particles with a flow agent to form a homogenous mixture;</li><li>placing said homogenous mixture in a die; and</li><li>operating said die to form said projectile.</li></ul>

0020The method may further comprise at least one of the following steps: <ul id="ul0003" list-style="none" compact="compact"><li>swaging the homogenous mixture in said die with a punch to form said projectile;</li><li>sintering the projectile; and</li><li>tumbling the projectile after it has been removed from said die.</li></ul>

0021Said plurality of metal particles may be comprised of one or more of the following metals: copper, bronze, brass, tin, zinc, steel, tungsten, tungsten carbide, ferrotungsten, aluminum and bismuth.

0022Said plurality of metal particles may be in the form of a powder, granule, flake, chip or a combination thereof.

0023Said air gun projectile may break apart when it strikes a hard surface.

0024Said homogenous mixture may further comprise an elastomer or an elastomer adhesive.

0025Said homogenous mixture may further comprise a polymer.

0026Said homogenous mixture may further comprise an organic material or an inorganic material.

0027Said flow agent may be N, N' Ethylene Bisstearamide.

0028To the accomplishment of the foregoing and related ends, certain illustrative aspects of the disclosed innovation are described herein in connection with the following description and the annexed drawings. These aspects are indicative, however, of but a few of the various ways in which the principles disclosed herein can be employed and is intended to include all such aspects and their equivalents. Other advantages and novel features will become apparent from the following detailed description when considered in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

0029<ul id="ul0004" list-style="none" compact="compact"><li><figref idref="f0001">FIG. 1</figref> is a perspective view of a projectile capable of being attracted by a magnet mixed with metal particles that are not attracted by a magnet.</li><li><figref idref="f0001">FIG. 2A</figref> is a perspective view of a projectile comprised of particles capable of being attracted by a magnet and a dried liquid elastomer.</li><li><figref idref="f0002">FIG. 2B</figref> is a perspective view of the projectile of <figref idref="f0001">FIG. 2A</figref>, with the belly band partially removed.</li><li><figref idref="f0002">FIG. 3</figref> is a perspective view of a tumbled projectile without a center band.</li><li><figref idref="f0003">FIG. 4</figref> is a perspective view of a single stage press and associated die/punch with the homogenous mixture filling the cavity of the die.</li><li><figref idref="f0003">FIG. 5</figref> is a perspective view of a single stage press and associated die/punch with the lower punch being at its lowest point and excess homogenous mixture ready to be removed.</li><li><figref idref="f0003">FIG. 6</figref> is a perspective view of a projectile being formed in the single stage press of <figref idref="f0003">FIG. 5</figref>.</li><li><figref idref="f0004">FIG. 7A</figref> is a front perspective view of a frangible slingshot projectile of the present invention.</li><li><figref idref="f0004">FIG. 7B</figref> is a side perspective view of the frangible projectile of <figref idref="f0004">FIG. 7A</figref>.</li></ul>

DETAILED DESCRIPTION

0030The innovation is now described with reference to the drawings, wherein like reference numerals are used to refer to like elements throughout. In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding thereof. It may be evident, however, that the innovation can be practiced without these specific details. In other instances, well-known structures and devices are shown in block diagram form in order to facilitate a description thereof.

0031<figref idref="f0001">FIG. 1</figref> is a perspective view of a projectile 100 having a belly band 105 and that is capable of being attracted by a magnet (not shown) mixed with metal particles that are not attracted by a magnet. More specifically, a low ricochet, non-toxic projectile 100, such as an air gun BB or a slingshot projectile, that can be attracted and retained by a magnet (not shown), is comprised of particles 110 that are attracted by both a magnet and by other particles 110 and one or more of the following: (a) metal particles 120 that are not attracted by a magnet; (b) one or more elastomers 130; (c) one or more polymers 140; (d) one or more elastomer adhesives 150; (e) one or more organic materials 160; and (f) one or more inorganic materials 170. Notwithstanding, it is also contemplated that projectile 100 could be comprised solely of materials that are not attracted to a magnet.

0032Particles 110 may be magnetic, such as magnetized iron. Particles 100 are preferably substantially spherical in shape with a preferred diameter of between 100-150 microns. Metal particles 120 that are not attracted by a magnet may include zinc, tin and/or copper particles. Metal particles 120 are preferably greater than 100 microns in diameter.

0033Elastomers 130, such as silicone or natural rubber, may be in liquid and/or powdered form. In liquid form, elastomers 130 should have a viscosity of approximately between 2 and 14 centipoise. In powder form, elastomer particles 130 should have a particle size of between 50-75 microns.

0034Polymers 140, such as latex, high density polyethylene (HDPE) and high density polyethylene (LDPE), may be in liquid and/or powdered form. In liquid form, polymers 140 should have a viscosity of approximately between 2 and 14 centipoise. In powder form, polymer particles 140 should have a particle size of between 50-75 microns.

0035Elastomer adhesives 150, such as Chloroprene Rubber Cemedine 575 or Master Bond X17, may be used and should have a viscosity of approximately between 2 and 14 centipoise.

0036Organic material 160, such as honey or maple syrup, may be in liquid and/or powdered form. In liquid form, organic material 160 should have a viscosity of approximately between 2 and 14 centipoise. In powder form, organic material 160 should have a particle size of between 50-75 microns. It is also contemplated that other non-toxic organic materials that decrease fines within a mixture can be used. Inorganic material 170, such as salt, may be in liquid and/or powdered form. For example, if salt is dissolved in a suitable liquid such as water, the viscosity of the resulting liquid should be approximately between 2 and 14 centipoise. It is also contemplated that other non-toxic inorganic materials that decrease fines within a mixture can be used. Further, nonmetallic particles will preferably have low temperature sintering properties.

0037Additionally, with regard to the powdered versions of elastomers 130, polymers 140, organic materials 160 and inorganic materials 170, the particles should be small enough so that they mix evenly with the magnetic metal particles 110 and/or nonmagnetic metal materials 120. It was found that the size of these particles should be between 50-75 microns in diameter. With regard to the liquid versions of elastomers 130, polymers 140, organic materials 160 and inorganic materials 170, it was determined through experimental testing that the viscosity should be approximately 3.0 centipoise. It was further determined that additives, such as water or xylene, may be added as to make said liquid versions of elastomers 130, polymers 140, organic materials 160 and inorganic materials 170 less viscous.

0038Projectiles 100 may also be swaged to a desired size and hardness and tumbled using suitable equipment known in the art for accomplishing said tasks. For example, projectiles 100 for use with air guns preferably have a diameter of between 0.169 to 0.5 of an inch and a preferred hardness that is capable of withstanding between 32 and 40 Kp of force, as measured by a tablet hardness tester.

0039When a desired liquid and/or solid component(s) or combinations thereof are mixed with suitable particles and the mixture is then dried or hardened by tumbling, it was found that the dried mixture would need to be roller compacted and processed accordingly in order to achieve the flow rate required for high speed production of projectile 100. More specifically, the homogeneous mixture is tumbled until all of the liquids have evaporated and/or solidified, and the metal particles are suspended within the residue of the evaporated liquids. The desired flow rate for high speed production is 35 seconds for 50 grams to flow through a Hall flowmeter (ASTM B213, MPIF No. 4, ISO No. 39231 with a 0.1 inch diameter calibrated orifice).

0040Agents such as magnesium stearate (not shown) may be added to roller compacted mixtures and non-roller compacted mixtures in order to increase the flow rate of the mixtures if need be. More specifically, it is contemplated that magnesium stearate in powdered form that is 0.001% to 35% of the homogenous mixture by weight could be used.

0041It should be noted that materials in liquid and/or powdered form(s) such as: (a) elastomers 130; (b) polymers 140; (c) elastomer adhesives 150; (d) organic materials 160; and (e) inorganic materials 170 help reduce particle fines when mixed with particles that have a high percentage of fines. Particle fines can accumulate on the tooling and cause serious damage to expensive equipment. The above listed materials, when mixed with particles 110 and metal particles 120, also help reduce the density of air gun projectiles 100, if so desired.

0042The following examples are offered solely to better explain the present invention and nothing contained therein should be construed as a limitation.

Example 1

0043Iron (93.5% by weight), zinc (4% by weight) and copper powders (2% by weight) are combined with 0.5% magnesium stearate (by weight) and mixed. The mixture is converted into suitable air gun projectiles 100 using a single stage or rotary press (not shown). The resulting projectiles 100 may also be tumbled to increase their roundness and lubricated with a non-toxic rust preventative as is well known in the art. The product of this example would be best suited for an air gun having a less powerful spring.

Example 2

0044Iron (94.15% by weight), tin (4% by weight), HDPE powder (0.75% by weight), liquid latex (1%) and N, N' Ethylene Bisstearamide (0.1% by weight) are combined and mixed, and the resulting mixture is processed through a commercial roller compactor in order to increase the flow rate of the mixture. The desired flow rate for high speed production is 35 seconds for 50 grams to flow through a Hall flowmeter. The roller compacted mixture is then converted into suitable air gun or sling shot projectiles 100 using a single stage press or rotary press (not shown). The projectiles 100 may also be tumbled to increase their roundness and lubricated with a non-toxic rust preventative as is well known in the art.

0045It should be noted that projectiles 100 suitable for air guns made by the methods of this invention should have a resulting diameter of between 0.169 to 0.5 of an inch. The air gun projectiles 100 may also be plated with copper or zinc after the tumbling phase if desired. Plating increases the hardness of the projectiles 100, and improves their aesthetics. If harder projectiles 100 are required, projectiles 100 may be swaged or compressed to a desired hardness using a suitable die or other tools or processes currently known in the art. Projectiles 100 may also be sintered by processes known in the art, and plated with copper or zinc if desired.

0046More specifically, sintering the frangible projectile of the present invention will help prevent rust, and is similar to a cold bluing process. Sintering temperatures for both air gun and slingshot projectiles should be in a range of between 200-1,600°F, though sintering of slingshot projectiles is not necessarily preferred.

0047In a further preferred embodiment of the present invention, projectiles 100 are lead free, and metal particles 120 may be from one type of metal or a combination of particles of various metal types. Copper, bronze, brass, tin, zinc, steel, tungsten, tungsten carbide, ferrotungsten, aluminum and bismuth are examples of suitable metal particles 120. Metal particles 120 may be in the form or shape of a powder, granules, flake, chip, or other compactable particulate forms or a combination thereof.

0048Having now generally described the preferred composition of projectiles 100, a preferred method of manufacture will now be described. More specifically, as shown in <figref idref="f0001">FIG. 2A</figref>, metal particles 120 may be mixed with a suitable non-toxic (meaning pharmaceutical grade) flow agent 200 and mixed until a homogenous mixture 220 is obtained. Flow agent 200 is preferably N, N' Ethylene Bisstearamide, but other types of flow agents may also be used without affecting the overall concept of the present invention. The amount of flow agent 200 added to the metal particles 120 will depend on the preferred rate of flow the mixture 220 requires for maximum production rate efficiency, and also the desired frangibility of the resulting air gun or slingshot projectile 100. An addition of 0.2% (weight of the total weight of the particles) of flow agent 200 is a good starting point. By way of example, a suitable flow rate would be less than 35 seconds for 50 grams of homogenous mixture 220 flowing through a professional flow meter.

0049Like the projectile shown in <figref idref="f0001">FIG. 1</figref>, the projectile of <figref idref="f0001">FIG. 2A</figref> also has a belly band 205 that may extend around the circumference of the projectile. <figref idref="f0002">FIG. 2B</figref> is a perspective view of the projectile of <figref idref="f0001">FIG. 2A</figref> with belly band 205 partially removed.

0050A pre-measured amount of homogenous mixture 220 is then placed inside of a suitable die (not shown) having the dimensions of the desired resulting projectile 100. Homogenous mixture 220 is then swaged or compressed inside the die using corresponding internal and external punches (also not shown). One or more dies (not shown) may be used in the swaging process. As described more fully below, a single stage press may be used or a press having multiple dies may also be used, such as a rotary table press. The resultant projectile 100, such as a BB, pellet or slingshot projectile, breaks apart into small pieces when striking a hard surface such as a rock, a steel plate or concrete.

0051The minimum diameter of the preferred embodiment of projectile 100, such as a BB or pellet, will be 4.3 MM or .171 of an inch, and the maximum diameter of the preferred embodiment of BB or pellet 100 will be 12.7 MM or 0.5 of an inch. Air gun BB or pellet 100 may have the shape of a conventional copper or zinc plated iron BB or any pellet shape commonly known in the art. The preferred size of the slingshot projectiles will be .25 of an inch up to .75 of an inch, and the shape will be similar to BB or air gun projectiles. The slingshot projectiles may be sintered if desired but tumbling is not recommended, as a sharp belly band will create more trauma if these projectiles are used for hunting.

0052<figref idref="f0003">FIG. 4</figref> is a perspective view of a single stage press comprised of an upper punch 400, a die 410, a homogenous mixture 420 (which includes the flow agent) and a lower punch 430. <figref idref="f0003">FIG. 5</figref> illustrates the single stage press of <figref idref="f0003">FIG. 4</figref>, but with lower punch 430 being at its lowest point and excess homogenous mixture 420 ready to be removed from said press. <figref idref="f0003">FIG. 6</figref> is a perspective view of projectile 100 being formed in the single stage press of <figref idref="f0003">FIG. 5</figref>. Ideally, the single stage press will impart 4.8 Kn to 6 Kn of force with minimal dwell time to create an air gun projectile and 4.8 Kn to 6 Kn of force with minimal dwell time to create a slingshot projectile.

0053<figref idref="f0004">FIG. 7A</figref> is a front perspective view of a frangible slingshot projectile 700 of the present invention. Projectile 700 is generally spherical, but comprises a belly band 702 and at least one fracture, notch or groove 704 in an outer surface 706 of projectile 700. Belly band 702 may extend along the circumference of projectile 700. Fractures 704 aid in the disintegration of projectile 700 upon impact with its target, and are preferably comprised of a groove or series of grooves, as best shown in <figref idref="f0004">FIG. 7B</figref>, which is a side perspective view of the frangible projectile 700 of <figref idref="f0004">FIG. 7A</figref>.

0054With respect to air gun projectiles, it has been determined through testing that the resulting projectiles will be frangible enough to break apart into smaller pieces when striking a hard surface (such as a steel plate) from approximately 15 feet away at velocities as low as 150 feet per second, but durable enough to withstand a reasonably strong air gun magazine spring. By comparison, conventional air gun projectiles tend to stay intact and ricochet off a hard surface, oftentimes striking the air gun user, when fired from a similar distance and at a similar velocity.

0055By way of example, the following fragment size analysis was conducted on projectiles of the present invention striking a steel plate having a thickness of approximately 0.092 of an inch from a distance of approximately 15 feet at velocities ranging from 235-550 feet per second: <tables id="tabl0001" num="0001"><table frame="all"><tgroup cols="4"><colspec colnum="1" colname="col1" colwidth="20mm" /><colspec colnum="2" colname="col2" colwidth="18mm" /><colspec colnum="3" colname="col3" colwidth="47mm" /><colspec colnum="4" colname="col4" colwidth="46mm" /><thead><row><entry align="center" valign="top"><b>Sieve size</b></entry><entry align="center" valign="top"><b>Microns</b></entry><entry align="center" valign="top"><b>Amount Recovered (grams)</b></entry><entry align="center" valign="top"><b>Percentage of Total Amount</b></entry></row></thead><tbody><row><entry align="center">60</entry><entry align="center">250</entry><entry align="center">50.5</entry><entry align="center">68.6%</entry></row><row><entry align="center">80</entry><entry align="center">177</entry><entry align="center">22.9</entry><entry align="center">31.1%</entry></row><row><entry align="center">100</entry><entry align="center">150</entry><entry align="center">0.12</entry><entry align="center">0.16%</entry></row><row><entry align="center">150</entry><entry align="center">100</entry><entry align="center">0.09</entry><entry align="center">0.14%</entry></row></tbody></tgroup></table></tables>

0056What has been described above includes examples of the claimed subject matter. It is, of course, not possible to describe every conceivable combination of components or methodologies for purposes of describing the claimed subject matter, but one of ordinary skill in the art may recognize that many further combinations and permutations of the claimed subject matter are possible. Accordingly, the claimed subject matter is intended to embrace all such alterations, modifications and variations that fall within the spirit and scope of the appended claims. Furthermore, to the extent that the term "includes" is used in either the detailed description or the claims, such term is intended to be inclusive in a manner similar to the term "comprising" as "comprising" is interpreted when employed as a transitional word in a claim.