具体实施方式：
[0031]In an embodiment, this disclosure is directed to manufacturing a snow sliding device, such as a ski or snowboard, to include a material exhibiting shear rate-dependent shear resistance. The material, which may be non-Newtonian, may be incorporated in any of various elements of snow sliding device, either integrally or by insertion in voids within the device. The snow sliding device is shaped and laminated together. The resulting snow sliding device exhibits greater vibration control, durability, and flexibility than existing snow sliding devices.
[0032]Non-Newtonian materials have properties that distinguish them from other materials. As used herein, non-Newtonian materials are materials having a shear response that varies by shear rate. When subjected to an increase rate of shear deformation, non-Newtonian materials undergo a change in apparent rigidity and/or apparent viscosity. Non-Newtonian materials as described herein may belong to one of two general classifications: (1) non-Newtonian materials classified as pseudoplastic or shear-thinning materials demonstrate decreased apparent rigidity and/or apparent viscosity in response to an increasing shear rate; and (2) non-Newtonian materials classified as dilatant or shear-thickening materials demonstrate increased apparent rigidity and/or apparent viscosity in response to an increasing shear rate. For example, a dilatant material may behave like low viscosity fluid under small or absent shear deformation but behave as a highly viscous fluid under higher rates of shear deformation. Other dilatant materials may behave as a solid or quasi-solid material when subjected to high rates of shear deformation, while behaving as a low-viscosity fluid under low or absent shear deformation. Still other dilatant materials may behave as flexible or elastomeric solids or quasi-solids when subjected to little or no shear deformation, but as highly rigid solids under high shear deformation rates.
[0033]The normal or resting condition of a non-Newtonian material (i.e., the condition where the non-Newtonian material is experiencing little or no shear deformation) and the opposite or ending point where the non-Newtonian material is subjected to a high rate of shear deformation may define the endpoints of a portion of a spectrum; one end of the spectrum may be described as “fluidity,” while the other may represent “rigidity.” Some non-Newtonian materials may cover the full range of the spectrum, while others may cover only part of the spectrum. For instance, a non-fluid non-Newtonian material may range from soft, elastic or flexible at one extreme along the spectrum to a rigid solid at the other end, but may not arrive at a fluid or apparently fluid form, at least in the temperature range in which it is tested; the non-fluid non-Newtonian material in this example may still be defined as lying on the spectrum, as its softer extreme is closer in form to fluid than its more rigid extreme. Adjustment of forces that act on a non-Newtonian material, the types of ingredients in the non-Newtonian material, or the quantities of ingredients in the non-Newtonian material may shift the region on the spectrum represented by the non-Newtonian material toward the rigid or fluid end of the spectrum, or increase or decrease the span of the region on the spectrum for that material. As an example, a dilatant material subjected to a high rate of shear deformation may be driven in the direction of rigidity on the spectrum, while cessation of the shear deformation may drive the material toward fluidity.
[0034]As movement along the spectrum is affected by shear rate, the timescale over which shear force is applied to a non-Newtonian material may affect its movement along the spectrum. For instance, a gradually applied shear force to a dilatant material may result in a small or negligible increase in viscosity or rigidity, while a shear force applied rapidly may result in a drastic increase in viscosity or rigidity. As an example, a dilatant suspension of cornstarch in water, sometimes known as “Oobleck,” may support a person stepping rapidly or “dancing” on its surface, while allowing a person who stands or walks slowly on the surface to sink into the material; the opposite effect is observed in water-impregnated “quick-sand,” which demonstrates pseudoplastic properties, causing a swimmer trapped in the quicksand to sink faster when struggling harder. Timescale limits under which non-Newtonian behavior is observable may depend upon various factors, including characteristics of the force applied to the material, and the type of non-Newtonian material involved.
[0035]Non-Newtonian materials may be modeled according to a “power law,” wherein the apparent viscosity of the material, defined as viscosity in liquids or more generally viscosity-like resistance to shear forces, is characterized by the equation η=K{dot over (γ)}n-1, where η is the apparent viscosity of the material, K is a positive material-specific constant, and {dot over (γ)} is the applied shear rate. Where n is less than 1, the material represented in the equation is pseudoplastic, and the apparent viscosity of the material is proportional to a negative power of the applied shear rate. Where n is greater than 1, the material represented in the equation is dilatant, and the apparent viscosity of the material is proportional to a positive power of the applied shear rate. Note that the positive power may be a non-constant positive power; that is, the positive power may be approximately constant or may vary while still exceeding zero. For instance, (n−1) may vary between 0.5 and 3, but remain greater than zero, and still be considered a positive power for the purposes herein. Similar variations may be observed with regard to negative powers. Persons skilled in the art will also be aware that material properties of any material can be described by a single equation only within a limited range of parameters, and that a property described for a material is described for the material as subjected to parameters of typical use; thus, for instance, a dilatant material used in a snow-sliding apparatus is a material exhibiting shear-thickening behavior within the range of temperatures and forces to which that form of snow-sliding apparatus is subjected during intended use, i.e. during motion through or navigation through the range of forces and impacts presented by bodies of water. Similarly, a material described as elastic is a material that behaves in an elastic manner within the intended range of temperatures and forces, and, for instance, may become rigid at very low temperatures, fluid at very high temperatures, and unable to rebound from excessive forces.
[0036]A Newtonian material, in contrast to non-Newtonian materials as described above, is a material whose shear resistance may be modeled as constant, or essentially constant, over a range of conditions corresponding to its typical or intended use. Thus, as used in this disclosure a material is not non-Newtonian if its shear resistance is apparently constant under shear rates that may occur when such material is used as a component of a snow-sliding apparatus as described in this disclosure, even if the material may be shown to evince a slight variation in shear resistance based on shear rate; if for the purposes of its us in a snow-sliding apparatus the variation in shear resistance is small enough that the relationship appears constant without advanced testing equipment, the material is not non-Newtonian. Similarly, a material having essentially constant shear resistance across shear rates as measured in use consistent with a snow-sliding apparatus is not a non-Newtonian material for purposes herein, even if under significantly different temperatures, pressures, or other physical effects the material may be induced to behave in a non-Newtonian manner. As a non-limiting example, a plastic material that has been melted to the point where it behaves as a liquid may exhibit non-Newtonian responses at low shear rates, but may not exhibit non-Newtonian responses when in a solid form; this material would not be non-Newtonian, for purposes herein, if the material were solid at pressures and temperatures experienced during use in a snow-sliding apparatus.
[0037]Various mechanisms may cause dilatant behavior in a material, independently or in combination. In shear-induced ordering, alignment of particles in the dilatant material may increase as a shearing force is applied; increasingly aligned particles may behave in an increasingly rigid manner. In addition, or alternatively, particles within the dilatant material maybe ordered at low shear rates, and become increasingly disordered at higher shear rates, resulting in greater apparent viscosity or rigidity. Another factor which may contribute to dilatant behavior may be change in volume of one or more ingredients, such as molecules whose volume expands under shear forces; this increase in volume may increase apparent rigidity or viscosity of dilatant material. Another factor which may increase apparent rigidity and/or apparent viscosity in dilatant material may be friction between particles that increases with increased shear rate, inhibiting movement of particles past each other. An additional factor that may increase apparent viscosity or apparent rigidity with increased shear rate may be attraction between molecules that increases with application of shear force. Another factor that may cause dilatant behavior may be a shear force overcoming repulsive forces between particles, allowing them to clump together. In suspensions of particles in liquids or gels, increases in shear rate may cause micro assembly clusters that increase resistance to shear and viscosity.
[0038]An additional factor that may cause dilatant behavior may be observed in certain polymeric materials, wherein shear-induced crosslinking between molecular elements may increase viscosity and/or resistance to shear force. Another factor that may contribute to dilatant behavior may be the formation of shear-induced non-Gauss chains in polymeric materials. An additional factor that may contribute to dilatant behavior in polymeric materials may be the formation of space network structure in response to shear rate increases. It should be understood that the above list of interactions and mechanisms is not intended to be exhaustive, and that shear thickening behavior may be the result of any phenomenon or interaction, or combination of phenomena or interactions including those listed above and any others, as would be apparent to one skilled in the art. A non-limiting example of a dilatant polymer material is polyborodimethylsiloxane and chemical and physical analogs thereof.
[0039]In some embodiments, decrease in shear rate, for instance by reduction or removal of shearing force, may have the opposite effect in non-Newtonian material of increasing shear rate. For example, a dilatant material under a high shearing force may be apparently solid or viscous and may become increasingly soft or fluid as the shearing force is reduced or removed. A pseudoplastic material may become increasingly stiff or viscous as a shearing force is reduced or removed.
[0040]Several categories of non-Newtonian materials will now be described. It should be understood that this list is not intended to be exhaustive, and any suitable types of dilatant material are contemplated for use in the disclosed embodiments.
[0041]Non-Newtonian materials may include dilatant fluids. A dilatant fluid may possess the characteristics of a fluid until it encounters a shear force, whereupon the dilatant fluid will thicken (e.g., move toward rigidity), and behave more like a higher viscosity fluid, quasi-solid, or solid. The shear force may be supplied by any suitable form of agitation, including without limitation direct or indirect impact of an object against the dilatant fluid. The dilatant fluid may return to a lower-viscosity or more liquid state upon cessation or reduction of the shear force. Dilatant fluid may include a colloid, composed of suspended particles in a liquid medium. A non-limiting example of a liquid medium may be polyethylene glycol; a non-limiting example of particles suspended in the liquid medium may be silica particles. Any suitable medium or particles may be used. In the absence of shear force, or when being acted on by shear forces applied slowly, the particles may float freely in the liquid medium without clumping or settling, owing to a slight mutual repulsion between the particles. An increase in shear rate, for instance due to a sudden impact, may overcome the repulsion, allowing the particles to clump together, increasing viscosity or apparently solid properties. When the shear rate decreases, the repulsion may push the clumps apart, causing fluid-like behavior again. Dilatant fluids may be used to make films, resins, finishes, and coatings that exhibit dilatant behavior. Persons skilled in the art will be familiar with methods used to make films, finishes, and coatings using fluids.
[0042]Conversely, a pseudoplastic fluid may possess the characteristics of a higher-viscosity fluid, solid, or quasi-solid until it encounters a shear force, whereupon the pseudoplastic fluid will thin (e.g., move away from rigidity), and behave more like a lower viscosity fluid, or softer solid or quasi-solid. These types of non-Newtonian fluids may be incorporated in adhesives, such as glue or epoxy. Persons skilled in the art will be familiar with methods used to make films, finishes, and coatings using fluids.
[0043]Non-Newtonian materials may include dilatant gels. Dilatant gels may have the characteristics of high-viscosity fluids, quasi-solids, or intermediate forms. Such non-Newtonian gels may have a similar composition to non-Newtonian fluids but may exhibit higher apparent viscosity or rigidity. In some embodiments, dilatant gels have the same ingredients as non-Newtonian fluids but may exist in a gel form due to one or more of various factors, including additional ingredients that cause the liquid medium to become gelatinous or environmental conditions. Non-Newtonian gels may exhibit similar qualities to jellies, putties, or clays. At low or absent shear rates, dilatant gels may be deformed with application of little or no force, while at higher shear rates such as those resultant from the energy of a sudden impact, dilatant gels may become increasingly rigid, with an improving resistance to deformation. The mechanisms that cause dilatant behavior in other dilatant materials may cause dilatant behavior in dilatant gels. On the other hand, pseudoplastic gels may be rigid at low or absent shear rates, with a strong resistance to deformation, while at higher shear rates may be more readily deformed. The mechanisms that cause pseudoplastic behavior in other pseudoplastic materials may cause pseudoplastic behavior in pseudoplastic gels.
[0044]Dilatant fluids or gels may be encapsulated to produce another non-Newtonian material. Encapsulated dilatant fluids or gels may include containers filled with dilatant fluids or gels. Containers may include one or more flexible or rigid walls; walls may also be constructed wholly or in part of such non-Newtonian material. Containers may be designed to receive vibrations or impact forces and transmit the vibrations or impact forces to the dilatant fluid or gels. The resulting increase in viscosity or rigidity of enclosed dilatant fluids or gels may cause the apparent rigidity of the containers to increase, while the enclosed pseudoplastic fluids or gels may respond with a decrease in apparent rigidity.
[0045]Dilatant foams are another kind of non-Newtonian material. Dilatant foam may be formed by confining physically or chemically produced bubbles of gas in dilatant gel or fluid. The resulting material may be solidified. Dilatant foam may have similar behavior to other non-Newtonian materials; for instance, increased shear rate caused by a sudden impact or other event may cause dilatant foam to become more rigid, while under reduced shear rates the dilatant foam may be softer or more flexible, and pseudoplastic foams may exhibit an inverse response as described above.
[0046]Dilatant solids are another category of non-Newtonian materials. Dilatant solids may be produced by solidifying non-Newtonian gels or fluids, or by introducing dilatant material into solid objects. Processes such as extrusion or injection molding may be used to dilatant solids. Such non-Newtonian solids may exhibit similar behavior to other non-Newtonian materials; for instance a dilatant solid may be relatively flexible or elastic under lower shear rates but may be more rigid or hard when subjected to high shear rates, such as those resultant from a sudden impact. Similar mechanisms to those causing shear thickening in other dilatant materials may produce shear-thickening behavior in dilatant solids.
[0047]An additional kind of non-Newtonian material includes dilatant filaments. A dilatant filament may be formed by any suitable processes, or combination of processes, including, for example, injection molding, extrusion, or spinning out of a melt. The dilatant filament may exhibit the characteristics of a dilatant solid.
[0048]An additional kind of non-Newtonian material includes impregnated fibers. An impregnated fiber may include, for example, a fiber or yarn that has absorbed, and/or is coated with, a dilatant material. The fiber may include a high strength polymeric fiber. Such non-Newtonian material may be a fluid and may retain its fluid characteristics after impregnation. This may help to ensure that the impregnated fiber will remain flexible, while endowing the fiber with non-Newtonian properties. Non-Newtonian-impregnated fibers and non-Newtonian filaments may be used in combination with or in lieu of any other fiber in any textile, endowing the textile with the non-Newtonian properties of the fibers and/or filaments, in combination with any additional properties of the textile.
[0049]An additional kind of non-Newtonian material includes impregnated fiber reinforced materials. An impregnated fiber reinforced material may include, for example, a fabric that has absorbed, and/or is coated with, a dilatant material. Additionally or alternatively, the impregnated fiber reinforced material may include previously impregnated fibers woven together to form a fabric. It is also contemplated that the impregnated fiber reinforced material may include a fabric made by weaving together non-Newtonian filaments and/or impregnated fibers. It is further contemplated that the fabric or fibers may be set into another medium to reinforce that medium. It is also contemplated that dilatant materials may be mixed in with the medium to impart non-Newtonian properties to the medium.
[0050]The impregnated fiber reinforced material may exhibit dilatant behaviors, similar to those described above with respect to the other categories of dilatant materials. For example, the coefficient of friction between the fibers, and/or between the fibers and the medium, may increase during an impact event, causing the fibers and/or medium to become more rigid, resulting in dilatant behavior. It is further contemplated that the fibers may form a substrate that, when a dilatant material permeates the fibers, holds particles of the dilatant material in place. When an object suddenly strikes the impregnated fiber reinforced material, the dilatant material will immediately thicken or harden, imparting its hardness to the overall construction. The flexibility of the overall construction will return upon removal of the force. Similarly, fibers of a fiber-reinforced material incorporating pseudoplastic material may act as a substrate retaining the pseudoplastic material at high shear rates, where the flexibility or elasticity of the fiber-reinforce material will increase in response to the high shear rates.
[0051]Non-Newtonian textile represents another category of non-Newtonian material. A non-Newtonian textile may be formed using any non-Newtonian fibers, non-Newtonian fiber-reinforced materials, or fibers impregnated with non-Newtonian material. Fibers or fiber-reinforced material may be formed into non-Newtonian textile by any suitable process for combining fibers or fiber-reinforced materials into textiles, including without limitation weaving fibers or fiber-reinforced materials and matting fibers or fiber-reinforced materials.
[0052]An additional kind of non-Newtonian material includes dilatant composites. A dilatant composite may include, for example, a solid foamed synthetic polymer. The solid foamed synthetic polymer may include an elastic, and/or an elastomeric matrix. The elastomeric matrix may retain its own boundaries without need of a container. The composite may also include a polymer-based non-Newtonian different from the solid foamed synthetic polymer. The polymer-based dilatant may be distributed through the matrix and incorporated therein during manufacture. The composite may also include a fluid distributed through the matrix. The combination of the matrix, non-Newtonian, and fluid may be selected such that the composite may be resiliently compressible (i.e., display resistance to compressive set), and preferably also flexible.
[0053]Another dilatant composite may include a solid, closed cell foam matrix and a polymer-based non-Newtonian, different from the matrix, distributed through the matrix. The composite may also include a fluid distributed through the matrix. The combination of matrix, dilatant, and fluid may be selected such that the composite may be resiliently compressible.
[0054]In either of the dilatant composites described above, any suitable solid materials may be used as the matrix, including, for example, elastomers. This may include natural elastomers, as well as synthetic elastomers, including synthetic thermoplastic elastomers. These may include elastomeric polyurethanes, silicone rubbers, and ethylene-propylene rubbers. Any polymer-based non-Newtonian that may be incorporated into the matrix may be used in the dilatant composites. The for instance, a dilatant polymer may be selected from silicone polymer-based materials, such as borated silicone polymers. The dilatant may be combined with other components in addition to the components providing the non-Newtonian behavior, including, for example, fillers, plasticisers, colorants, lubricants and thinners. The fillers may be particulates (including microspheres), fibrous, or a mixture of the two. It is contemplated that a borated siloxane-based material may be used as a dilatant.
[0055]An additional kind of non-Newtonian material includes dilatant layers. A non-Newtonian layer may include a layer of material formed from one of, or a combination of, the above categories of non-Newtonian materials. The non-Newtonian layer may be combined with layers having other properties, such that the combined layers may exhibit some form of non-Newtonian behavior as a result.
[0056]The use of the terms “non-Newtonian materials,”“pseudoplastic materials,” and/or “dilatant materials” in the following description of snow-sliding apparatuses is meant to cover all categories of non-Newtonian, pseudoplastic, and/or dilatant materials known to those skilled in the art, including without limitation the categories and examples of non-Newtonian, pseudoplastic, and/or dilatant materials described herein.
[0057]Some embodiments described herein are directed to snow-sliding apparatuses, and methods for manufacture of snow-sliding apparatuses. As defined herein, a snow-sliding apparatus is a recreational device used by a person to traverse snowy surfaces by sliding on a substantially flat bottom surface. A snowy surface, as used in this disclosure, is a surface formed by the deposition of ice crystals and agglomerations of ice crystals on a solid substrate such as ground, frozen water, human-made surfaces, and the like. The snowy surface may be formed by natural precipitation of snow, sleet, freezing rain, and other precipitation depositing frozen water or freezing water in any forms or combinations. Snow may be deposited using artificial means, such as snow-producing machines commonly used on alpine and cross-country ski trails. A snowy surface may have crusts or layers of ice, compacted snow, fluffy or powered snow, nodules of ice, snow that has melted and refrozen one or more times to form granules of ice, and the like. A snowy surface may be groomed, where grooming is a process performed by humans, machines, or combinations thereof to make the snowy surface more suitable for one or more forms of snow-sliding or other recreation. Grooming may include, without limitation, grading or leveling, compacting, raking, forming into topographical features such as moguls, ramps, jumps, half-pipes, and the like. A snowy surface may be ungroomed, or “natural,” as well, where an ungroomed surface is a surface formed solely by deposition of precipitation, natural processes affecting deposited precipitation (for instance, drifting because of wind, melting and thawing, avalanches, or the like), and the passage of snow-sliding apparatuses as the surface is used for recreational purposes; a snowy surface may also be formed by a grooming-like process that emulates the conditions of a natural surface. A snowy surface may also include artificial surfaces created to imitate one or more characteristics of snowy surfaces as described above, using a combination of manufactured elements including textiles, polymers, and the like.
[0058]Particular features and forms of snow-sliding devices in various embodiments will be illustrated below. A snow-sliding device typically includes a base surface that slides on top of the snowy surface. The base surface is typically designed to slide on the snowy surface with low friction; the base surface may also include higher-friction zones or elements to grip the snowy surface and propel the snow-sliding device over the snowy surface. A snow-sliding device may include a device to secure one or more feet of a user to the snow-sliding device; devices may include “bindings” that engage specialized or generic footwear. Snow-sliding devices may include without limitation cross-country skis, skate skis, downhill or “alpine” skis of any type, telemark skis, and snowboards.
[0059]Turning now to FIG. 1, an exemplary embodiment of a method 100 of manufacturing a snow sliding device is illustrated. At step 105, a core is formed. An exemplary embodiment of a core 200, as seen from one side, is illustrated in FIG. 2A. Forming core 200 may include forming a core body 204. Core body 204 may be composed of any suitable material or combination of materials, including without limitation wood such as maple, ash, beech, poplar, okume, or other wood, plywood, fiberglass, laminated fiberglass, metal such as steel, titanium, aluminum, combinations of metals, or alloys of metals, composite honeycomb, foam, resin, carbon fiber, graphene, polyurethane, polyethylene, epoxy, or any other material combination usable to provide desired material properties to the core 200. Core body 204 may include an upper surface 208 and lower surface 212, which represent surfaces nearer to, respectively, a sliding surface and a surface on which a user stands. Core body 204 has a first thickness defining a first vertical distance from at least a first point 216 on the upper surface 208 to a corresponding at least a first point 220 on the lower surface 212.
[0060]At step 110, and still referring to FIG. 1, forming core 200 includes shaping core body 204 to include the first thickness and a second thickness, the second thickness defining a second vertical distance from at least a second point 224 on the upper surface to a corresponding at least a second point 228 on the lower surface, as illustrated in FIG. 2A. Second thickness may be less than first thickness: for example, first thickness may be a thickness at or near a point where a user stands on the snow-sliding device, which may be a point where there are bindings, for instance. Second thickness may be a thickness of a forward section of core 200, where a thinner construction for snow-sliding device is desired to permit some degree of flexibility. Core body 204 may be further shaped to include a third thickness, which may, for instance, be a thickness of a rearward section of core 200. Third thickness may be larger or smaller than second thickness. Third thickness may be greater or lesser than first thickness. As a non-limiting example, traversing core body 204 from front to back, a front section of second thickness may widen to a middle section of first thickness, and then taper down to a rear section of third thickness, which is slightly thicker than the front section.
[0061]In reference to FIG. 2A, forming the core body 204 may be performed in the same process as shaping the core body 204, or in a different process. In one embodiment, core body 204 may be formed using molding, such as injection molding; for instance, a mold having the shape of core body 204 may be prepared and filled with a liquified resin or metal, or a froth that is then cured or allowed to harden into resin, metal or foam. Curing may be performed by modifications of temperature of the mold contents, by passage of time, by exposure to additional chemicals, by exposure to air, or by irradiation including but not limited to irradiation with ultraviolet radiation. Core body 204 may then be removed or extracted from the mold. Shaping the core body 204 may be accomplished by the shape of the mold; that is, upon extraction of the core body 204 from the mold, core body 204 may already have first and second thicknesses. Core body 204 may be subjected to additional shaping after extraction, for instance by machining, shaving, or otherwise removing material to further shape core body 204; additional steps may alternatively include addition of material to core body 204 by additive means as described below, impregnation of core body 204 with one or more materials, sealing of an exterior surface of core body 204, lamination of one or more exterior layers to core body 204, or the like. As further non-limiting example, core body 204 may be initially formed as a hollow body, for instance using blow-molding or additive manufacture, and then filled with additional material, including without limitation resin, gel, foam, liquid, epoxy, or other material.
[0062]With continued reference to FIG. 2A, core body 204 may be formed by subtractive manufacturing. As used herein, subtractive manufacturing is any process that creates a part or product, such as core body 204, by removal of material from a previously existent object, which may have any shape. Subtractive manufacturing may be performed manually, for instance by cutting, sawing, or rasping material. Subtractive manufacturing may be mechanized, defined herein as performed using a device that restricts material-removal tools to one or more specific degrees of freedom, such as sliding or rotary motions; a non-limiting example is a lathe, a plane or knife constrained to a track, or a saw that slides or has material slid past on a track. A further example is a milling machine tool, which may include one or more rotary tools for material removal and one or more slides or other items for moving the one or more rotary tools relative to the object from which material is to be removed. Subtractive manufacturing may be performed using an automated manufacturing device, which may be any device that is controlled by an automated process; automated manufacturing device may be controlled by a logic circuit including one or more logic gates, by a finite state machine, a processor using Vonn Neumann or Harvard architecture with reference to a digital storage memory, a computer or computing device, a microprocessor, an analog circuit responding to one or more feedback systems, a mechanized automated system, any control system, or the like. As a non-limiting example, automated manufacturing device may include a computer numerical control (CNC) machine.
[0063]As shown for illustrative purposes in FIG. 2A, a core blank 232 may be provided, which may be composed of any material or combination of materials suitable for construction of core body 204 as described above. Core blank 232 may be initially formed by cutting or machining core blank 232 from a larger block of material. As a non-limiting example, a machine tool such as a CNC machine or hand-