Abstract:
A flange design providing improved strength, fracture resistance, and the like using corrugations extending substantially radially from an arbot aperture toward a rim portion. A spool or reel may include a tubular member to receive a stranded material wrapped therearound. A first flange comprising a core portion and an outer portion may secure to one end of the first flange engaging the tubular member. A second flange may secure to the other end of the tubular member. The core portion of a flange may comprise an arbor wall defining the perimeter of an arbor aperture. The arbor wall may be directly contacted and supported by a plurality of corrugations extending radially therefrom. The outer prortion of a flange may contact the core portion and extending radially away therefrom to an outer edge to restrain the stranded material in an axial direction.

Description:
RELATED APPLICATIONS 
       [0001]    This patent application is a divisional of co-pending U.S. patent application Ser. No. 12/498,198, filed Jul. 6, 2009, which application is a continuation of co-pending U.S. patent application Ser. No. 12/111,000, filed Apr. 28, 2008 (now U.S. Pat. No. 7,556,217, issued on Jul. 7, 2009), which application is a continuation of U.S. patent application Ser. No. 11/095,754, filed on Mar. 31, 2005 (now U.S. Pat. No. 7,364,113, issued Apr. 29, 2008), which application is a continuation of U.S. patent application Ser. No. 10/617,126, filed on Jul. 10, 2003 (now U.S. Pat. No. 6,874,726, issued Apr. 5, 2005), which application is a continuation of U.S. patent application Ser. No. 09/774,389, filed Jan. 29, 2001 (now U.S. Pat. No. 6,598,825, issued Jul. 29, 2003), which application is a continuation-in-part of U.S. patent application Ser. No. 09/434,609, filed Nov. 5, 1999 (now U.S. Pat. No. 6,179,245, issued Jan. 30, 2001), which application is a division of U.S. patent application Ser. No. 09/023,318, filed Feb. 13, 1998 (now U.S. Pat. No. 6,003,807, issued Dec. 21, 1999). Each of the foregoing is incorporated herein in its entirety by this reference. 
     
    
     BACKGROUND 
       [0002]    1. The Filed of the Invention 
         [0003]    This invention relates to spools and reels for receiving stranded materials, and, more particularly, to novel systems and methods for producing plastic flanges for reels and spools as take-up of electrical wire during manufacture. 
         [0004]    2. The Background Art 
         [0005]    Spools and reels have suffered from a lack of intelligent application of technology for many years. Spools date back hundreds if not thousands of years. Wooden spools and reels have been used in the textile industry as well as various electrical industries for many years with almost no innovation in their structures. Some use of plastic materials began a few decades ago. Nevertheless, manufacturing techniques continue to fall short of implementing all of the principles of engineering that are available. 
         [0006]    Manufacturing techniques tend to focus on the simplicity of manufacture, and the simplicity of design, rather than the optimization of strength, weight, stiffness, non-catastrophic failure modes, and the like. Some of these latter considerations have been found to be significant in the manufacture and use of plastic spools and reels. Accordingly, developments by Applicant have provided improved methods for providing spools and reels having substantially reduced weight with improved stiffness and cost. Moreover, failure modes are available to provide “graceful degradation” of performance rather than catastrophic failure of spools and reels in situations such as the dropping of loaded reels or spools. 
         [0007]    Spools and reels are used in many industries. However, in the wire and cable industry, the comparative weight of stranded material on a reel or spoon is greater than others of similar size in other industries. Fracture of flanges near an outer diameter thereof is common if dropped. Likewise, due to the conventional shapes of central tubes (hubs, cores, etc.), the junctions with flanges are not inherently resistant to fracture from impact loads caused by dropping. Dropping from a working bench is common for reels and spools. Manufacturing processes for manufacturing reels and spools, as well as manufacturing processes for wire and other stranded materials, typically compels smooth circumferential edges at the outermost diameter of a flange. Accordingly, a spool not retained on an arbor during use (using the wire, rather than manufacturing and taking up the wire) may roll easily across any flat surface. Thus, while a spool or reel is considered tare weight in shipping wire and cable, and a disposable item whose cost is to be minimized a spool or reel must function reliably and durably during its entire useful life. 
         [0008]    Otherwise, a substantial length of stranded material may be damaged beyond use. The material held on a spool or reel having a value of a few dollars may itself have a value of one thousand times the cost of a spool. A value two orders of magnitude greater than that of the spool is routine for wire of common usage. 
         [0009]    3. State of the Art 
         [0010]    Stranded materials, upon manufacture, are typically taken up directly onto a reel or spool. The take-up spool or reel receives the strand directly from the last step in the manufacturing process. Thereafter, the filled spool is effective for storage and handling purposes. Upon sale or distribution, the spool is often placed on an arbor, either alone or with other spools, for convenient dispensing of the linear or stranded material. Linear or stranded materials include electrical wire whether in single or multiple strands and cable (comprising multiple wires), rope, wire rope, hose, tubing, chain and plastic and rubber profile material (generally any polymeric or elastomeric extruded flexible material). 
         [0011]    In general, a host of elongate materials as diverse as pharmaceutical unit dose packages, fiberoptic line and log chains are stored on spools. Likewise, ribbon, thread and other stranded materials are wrapped on spools. 
         [0012]    The requirement for a spool in the manufacture and handling of wire is substantially different from spools in the textile industry. For example, the weight of wire is several times the weight of thread or rope. The bulk of wire, which translates to the inverse of density, is substantially lower for wire than for hose, tubing or even chain. 
         [0013]    Meanwhile, most spools are typically launched on a one way trip. The collection and recycling of spools is hardly worth the effort, considering that their materials are not easily recyclable. 
         [0014]    In the art, a typical spool has a tube portion extending between two flange portions positioned at either end of the tube portion. A spool may have a rounded rim or rolled edge at the outermost diameter. This rim serves structural as well as aesthetic and safety purposes. Spools may be manufactured in a variety of tube lengths. Each flange is fitted by some fixturing to one end of the tube and there retained. Details of spools are contained in the U.S. Pat. No. 5,464,171 directed to a mating spool assembly for relieving stress concentrations, incorporated herein by reference. 
         [0015]    The impact load of a spool of wire dropping from a bench or other work surface to a floor in a manufacturing environment is sufficient to fracture the spool in any of several places. Fracture may damage wire, preclude removal, or release the wire in a tangled, useless mass. 
         [0016]    Spools may break at the corner where the tube portion meets the flange portion or may fracture at an engagement portion along the tube portion. Spools may break near the corner between the flange and the tube portion where a joint bonds or otherwise connects the tube portion to the flange portion. 
         [0017]    Spools and reels experience significant breakage during drop tests when manufactured in styrene or styrene-based plastics such as ABS. Polyolefins are very tough materials. Tough means that a material can tolerate a relatively large amount of straining or stretching before rupture. By contrast, a material which is not tough will usually fracture rather than stretch extensively. As a result, when a reel of wire is dropped, the energy of impact breaks the spool. 
         [0018]    Polyolefins, by contrast, may actually be drawn past yielding into their plastic elongation region on a stress-strain chart. Polyolefins thus elongate a substantial distance. The result is that olefinic plastics will absorb a tremendous amount of energy locally without rupture. Thus, the wire on a spool which has been dropped does not become a tangled mat of loops. 
         [0019]    Given their toughness, olefinic parts will bend, strain, distort, but usually not break. Nevertheless, olefinic plastics are not typical in the art of wire spools. Polyolefin parts are not bonded into multi-piece spools. However, lack of a solvent is one problem, lack of a durable adhesive is another. Therefore, any spool would have to be manufactured as unit of a specific size. The inventory management problem created by unique spools of various sizes is untenable, although the cost of some olefinic resins is lower than that of styrene-based resins. 
         [0020]    Moreover, the cycle time of molds directly related to material properties is usually much faster for styrene-based resins. The designs available use wall thicknesses which result in warpage as well. All these factors, as well as others, combine to leave olefinic resins, and bonded parts made therefrom, largely unused in the spool industry. 
         [0021]    In drop tests, a spool may be dropped axially, radially or canted off-axis. In a radial drop, spools that break typically fail near the middle of the length of the tube. In axial drops, flanges may separate from tubes in failed spools. In an off-axis drop, flanges typically fracture, and may separate from tubes, releasing wire. 
         [0022]    Large spools are typically called reels in the wire industry. Heavy-duty reels of 12 inches in diameter and greater (6 feet and 8 feet are common) are often made of wood or metal. Plastic spools of 12-inch diameter and greater are rare and tend to be very complex. The rationale is simple. Inexpensive plastics are not sufficiently strong or tough to tolerate even ordinary use with such a large mass of wire or cable wrapped around the spool. 
         [0023]    Moreover, large flanges for reels are very difficult to manufacture. Likewise, the additional manufacturing cost of large spools is problematic. High speed molding requires quick removal after a short cycle time. Flanges are typically manufactured to have very thick walls. Increased thicknesses directly lengthen cycle times. Thus, designs do not scale up. Therefore, the flanges have very slow cooling times and molding machines have low productivity in producing them. 
         [0024]    Styrene plastic is degraded by recycling. That is, once styrene has been injection molded, the mechanical properties of the resulting plastic are degraded. Thus, if a spool is recycled, ground up into chunks or beads and re-extruded as part of another batch, the degradation in quality can be substantial. Olefinic plastics improve over styrene-based plastics in that olefinic plastics can be completely recyclable. The mechanical properties of an olefinic plastic are virtually identical for reground stock as for virgin stock. 
         [0025]    In reels, a 12-inch diameter unit is instructive. Such a spool is usually manufactured of wood. Nevertheless, a plastic spool in 12-inch diameter may also be manufactured with a pair of plastic flanges holding a layered cardboard (paperboard) tube detained therebetween. The flanges are typically bolted together axially to hold the tube within or without a circumferential detent as with wooden reels. 
         [0026]    The reels have an additional difficulty when they are dropped during use. The flanges do not stay secured. The flange and tube are often precarious wooden assemblies held together by three or more axial bolts compressing the flanges together. The tube is prone to slip with respect to the flanges, breaking, tilting or otherwise losing its integrity under excessive loads. Such loads result from the impact of dropping onto a floor from a bench height or less. For the largest reels, rolling over or into obstacles or from decks during handling is more likely to be the cause of damage. 
         [0027]    Very large cables, having an outside diameter up to several inches is taken up during manufacturing on a very large reel, from two feet to eight feet in diameter. The current state of the art dictates wooden reels comprised of flanges capturing a barrel-like tube of longitudinal slats therebetween. The two flanges are held together by a plurality of long bolts extending therethrough. 
         [0028]    Wooden reels are not typically recyclable. A splinter or blemish in a reel can damage insulation on new cable or wire wrapped therearound at the manufacturing plant. Damaged insulation destroys much of the value of a reel of cable or wire. That is, the wire must be spliced, or may have damage extending over several wrapped layers of wire. Splices segmenting the original length of wire wrapped on the reel add costs in labor, reliability, service and the like. 
         [0029]    Wood cannot be recycled and reconstructed cost effectively. In addition, the plurality of bolts and nails must be removed with other related metal hardware. The reels do not effectively burn without the labor investment of this dismantling operation. 
         [0030]    Also, a wooden reel that is slightly out of adjustment, damaged, or broken, is problematic. A broken reel leaves a large area splintered to damage wire insulation. A reel which is loose will tilt and twist as the slats shift with respect to the flanges. 
         [0031]    Steel reels tend to be more frequently recyclable. However, each must be returned in its original form to be reused. Thus, the bulk of transfer is as large as the bulk of original shipment, although the weight is less. Also, steel is heavy, subject to damage by the environment such as by stains, rust, peeling of paint, denting, accumulation of coatings or creation of small burrs on surfaces and corners. For example, when a reel is rolled over a hard surface, sharp objects, grit or rocks tend to raise small burrs on the outer edge of the flange. Similarly, contact with any sharp or hard object can raise burrs on the inside surfaces of the flanges. 
         [0032]    As with wooden reels, only to a greater extent, a burr on a steel reel tends to act like a knife, slicing through insulation and ruining wire. Perhaps the most difficult aspect of burrs is that they are hardly detectable at sizes which are nevertheless highly damaging to insulation. Of course the weight and cost of steel reels is another factor in the difficulty of employing them for delivery of cable. 
         [0033]    What is needed is a design for large (12 inches greater diameters) and small diameter (typically 6½-inch outside diameter) plastic spool flanges, which can tolerate the energy of being dropped when fully wrapped with wire. In addition, even in the standard styrene-based plastic spools, a better design is desired. What is needed in large reels of from a foot to eight feet approximately in outside flange diameter is a reel which is dimensionally stable, maintains structural integrity in service and during accidental dropping, which will not fracture or separate at a flange if it is dropped, and which is economically recyclable. 
         [0034]    In a large reel, on the order of two to eight feet in diameter, what is needed is a lightweight, high-strength reel. The reel should not tend to damage wire when scratched, gouged, or otherwise having a burr raised on any key surface. Similarly, a large reel should be resilient enough that it does not maintain a permanent set, such as a steel reel will, when damaged. A plastic reel should be formed in a design that resists fracture and of a material which is tough. The material should be flexible enough that a burr will not damage insulation. A large reel should be recyclable. Recycling is most efficient if a reel can be reground near the site of use. Empty reels are more voluminous than they are heavy. 
         [0035]    Moreover a design is needed that provides improved toughness by virtue of design, regardless of the toughness of the material. Catastrophic failure of reels and spools limits their applicability within the wire and cable industry. The risk of losing the use of the stranded material held thereon is not to be risked for the cost of using plastic spools and reels. 
       BRIEF SUMMARY AND OBJECTS OF THE INVENTION 
       [0036]    In view of the foregoing, it is a primary object of the present invention to provide spools and reels and a method of designing them that will optimize strength, stiffness, fracture, distortion, toughness, and so forth at various locations within the flanges for survival of drop tests. 
         [0037]    It is an object of the invention to provide various flange designs that can absorb shock or impact loads without completely fracturing. 
         [0038]    It is an object of the invention to provide a design of, and method for designing, flanges of spools and reels having controlled fracture and controlled distortion in order to optimize survival of flanges and the integrity of the flange-to-tube transitions in configurations of spools having minimum weight and highest produceability in molding outputs. 
         [0039]    It is an object of the invention to provide selective distortion, stiffness, and fracture of a flange in order to protect the integrity of a core or hub region of the flange. 
         [0040]    It is an object of the invention to provide an eccentric application of impact loads transmitted from a rim toward a core region of a flange connecting to a tube portion, whether the tube is initially formed integrally or separately from the flange. 
         [0041]    It is an object of the invention to provide multiple regions within the web of a flange, with the regions adapted to provide differing material properties, including different sections, moments of inertia, stiffness, strength, toughness, fracture-resistance, fracture-susceptibility, and the like. 
         [0042]    It is an object of the invention to provide increased stiffness in the web while employing thinner walls, yet such that impact loads will not separate a rim and web from a core region of a flange, but maintain mechanical integrity of the flange especially in the tube transition region. 
         [0043]    The invention solves this multiplicity of problems with flanges for plastic spools and reels formed in a multi-piece structure preferably by molding from olefinic, ABS, styrenic, and other plastics. Some of the designs may be made tough, even when manufactured of styrene-based plastics. The designs are particularly well adapted to manufacture using molded polyethylene and polypropylene or similar olefinic plastics regardless of tube (core) retention methods. 
         [0044]    The structures and methods of the invention apply to spools and reels of all sizes. However, a structure that can be injection molded in a 6½-inch flange diameter may have to be roto-molded (tumble-molded) to produce an eight foot diameter spool or reel. Consistent with the foregoing objects, and in accordance with the invention as embodied and broadly described herein, an apparatus and method are disclosed, in suitable detail to enable one of ordinary skill in the art to make and use the invention. 
         [0045]    In one presently preferred embodiment of an apparatus in accordance with the invention, a central tube or core section may be disposed between two flanges. Construction of the core and flange joints may be done in accordance with various approaches known in the art, as well as those articulated in U.S. Pat. No. 5,464,171, incorporated herein by reference. 
         [0046]    Nevertheless, a tube may be completely hollow, ribbed or corrugated, itself. Alternatively, tubes may be arranged to fit within cavities formed in flanges, or to fit outside a sleeve protruding inwardly from a flange, or both at once. In certain embodiments, a flange and tube may be molded in a single piece with a mating tube and associated flange being molded in another piece. The two pieces may then be bonded together by a suitable means to provide a complete spool or reel. 
         [0047]    Hybrid spools and reels may be formed using different materials for flanges than for tubes (cores). In other embodiments, a single material may be used for both flanges and tubes assembled from two or more parts. In one presently preferred embodiment, a cardboard tube may be adapted to fit over sleeves protruding from integrally formed flanges extending therefrom. 
         [0048]    In one embodiment, flanges may be corrugated to provide a multiplicity of beneficial features. Thickness of walls, more complete closure of cavities (on all sides but one, for example), selective fracture resistance and fracture susceptibility, stiffness, strength, rigidity, a moment of inertia, a section, and so forth may be affected. 
         [0049]    Corrugations may be arranged in a spoke-like configuration extending radially from a core or a hub portion of a flange. Alternatively, corrugations may extend radially at uniform or non-uniform circumferential angles. Corrugations may extend circumferentially between orthogonal surfaces thereto or surfaces non-orthogonal thereto in order to optimize weight, strength, stiffness, toughness, and other significant functionality. 
         [0050]    Corrugations may terminate in selective angles with respect to tangents to the hub (core) portion, and at different selected angles with respect to tangents to a rim or outer circumference of a flange. Moreover, an angle of sweep measured between a tangent of a corrugation edge proximate a core and such an angle measured proximate a rim may differ by any suitable number of degrees. Accordingly, corrugations may be formed to direct loads radially between a hub and rim portion of a flange. 
         [0051]    Alternatively, corrugations may be arranged to preclude direct transfer of loads normal to any tangents to a hub, rim, or both. Loads may include compression, tension, shear, bending, and so forth. Corrugation surfaces may be designed to provide a selected strength, stiffness, and toughness at any location within a flange. Corrugations may provide axial loading to retain stranded material, even after substantial damage to a flange. Moreover, the balance between strength, stiffness, and toughness may be designed specifically to be different at different locations within a flange. Accordingly, flanges may be designed specifically to address loading caused by different types of falls, a major source of damage in use. 
         [0052]    Eccentric and tangential interception of corrugations by a hub of a flange may be designed to promote absorption of energy of an impact, by distortion, selective fracture, or by rigid survival. However, in certain embodiments, portions of a flange may be designed to fail to a selected extent in a selected region in order to protect other portions of the flange that would result in more costly damage if allowed to fracture. 
         [0053]    Thus, for example, outer portions of a flange may be permitted to crush, bend, break, and so forth in order absorb certain loads. The rim having greater circumference, more material may be naturally provided for absorbing such damage. Meanwhile, a hub may be configured to minimize damage, since a hub may be substantially smaller than a rim (outer diameter or outermost portion) of a flange. In one presently preferred embodiment, bending loads may selectively fracture corrugation walls on one axial side, while transferring loads away to other areas. This re-distribution may reduce fractured circumference at the core, maintaining integrity while permitting fracturing of adequate length to absorb shock loads. 
         [0054]    Even near a hub, geometries of flanges may promote selective fracture. For example, selected portions of corrugations may be designed to have thicknesses, angles, and loads calculated to cause a fracture of a limited length and direction . Other nearby locations may be configured with geometries, materials, thicknesses, and so forth to virtually preclude fracture in a similar circumstance. Both features, one susceptible to ready fracture at a known location, and one resistant to expected fracture at a nearby location may provide selective fracture for absorption of energy without catastrophic failure. Catastrophic failure may be regarded as a failure that is likely to destroy the contents of a spool or reel, render it otherwise useless due to increased effort to retrieve, or create an impossibility or difficulty of supporting and retrieving stranded materials, and the like. 
         [0055]    In other embodiments, circumferential corrugations may be used. Moreover, angled or curved corrugations may be used in combination with one another, or circumferential corrugations, or with surfaces of various configurations in order to optimize fracture toughness, strength, stiffness, etc. In one embodiment, a flange may be subdivided radially to provide portions having greater or lesser resistance to fracture or energy absorption. Corrugations may have axial depth. Axial depth may be constant or variable in a radial, axial, or circumferential direction. Nevertheless, molding considerations may provide or benefit from certain uniformities. 
         [0056]    Inner surfaces of flanges, those surfaces in contact with the stranded materials stored thereon, may be smooth or corrugated. Accordingly, distances across corrugations may be uniform or non-uniform in a radial, circumferential, or axial direction. Moreover, a directorix may be defined for each corrugation, and even each surface extending in a more-or-less radial direction. Thus, adjacent surfaces or directrices defining surfaces extending radially but connected circumferentially by orthogonal or other surfaces, may have different angles, and may be angled, curved, both, or alternating. 
         [0057]    As a practical matter, inner surfaces or interior surfaces of a spool may desirably be designed to extend circumferentially a greater portion of circumference of a flange at any given radius. Thus, the inner, clear span of a stranded material between axial support surfaces will be a relatively lesser fraction of the overall circumference at any radius. Nevertheless, multiple corrugations having sufficiently high frequency to provide short clear spans may obviate any necessity for non-uniformity in a circumferential expanse of any corrugation on an inner or outer surface of a flange. Likewise, surface liners, such as a paperboard, or re-ground plastics, and other inexpensive materials may be installed during manufacture, or after manufacture, to separate wire or other stranded materials from touching an interior flange surface or from tending to escape axially into corrugations corresponding to exterior flange surfaces. 
         [0058]    Various alternative embodiments of corrugated spools and reels may be fabricated to have corrugations in various shapes, orientations, and locations. For example, corrugated core regions associated with the portion of a flange within an outer diameter of a connecting tube may be corrugated in various configurations, just as the outer portion of the flange may be corrugated in various configurations. 
         [0059]    The core and outer portion of a flange need not be corrugated in the same manner, the same pattern, the same direction, or with any other similar orientation. Moreover, the core and the outer portion of a reel may be made as separate pieces, and secured together with the same fastener that secures the intervening or connecting tube in place. Alternatively, a different fastener may hold the core and outer portion together, while a tube fastener holds the flange to the tube. 
         [0060]    In selected embodiments, a core may not require corrugations, but may have apertures to accommodate the two prongs of tools or a tool such as a stapler. A true stapler has an active prong comprising the head, which delivers the staple, and an inactive or anvil prong, for receiving the staple and bending the ends thereof. 
         [0061]    The apertures allow access to a tube by a two-prong or double prong tool (e.g. stapler), and to the portions of a reel flange designed to hold the tube. Access may be provided by an aperture and a recess (part of a corrugation) or by a pair of corrugations located radially inside and radially outside of the tube. 
         [0062]    In selected embodiments, cross-sections may be defined to run radially, and thus vary in circumferential dimension along a radius. Cross-sections may be rectangular, trapezoidal, sinusoidal, or of any variety, provided in any other corrugated system. Alternatively, corrugations may be disposed to run with cross-sections normal to a circumferential direction. That is, a corrugation may extend with its own longitudinal direction lying along a circumferential path about a flange, that is, wherein a cavity of a corrugation cross-section appears in the radially and axially extending plane with respect to the flange. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0063]    The foregoing and other objects and features of the present invention will become more fully apparent from the following description and appended claims, taken in conjunction with the accompanying drawings. Understanding that these drawings depict only typical embodiments of the invention and are, therefore, not to be considered limiting of its scope, the invention will be described with additional specificity and detail through use of the accompanying drawings in which: 
           [0064]      FIG. 1  is a perspective, exploded view of one embodiment of a spool made in accordance with the invention; 
           [0065]      FIG. 2  is a schematic end elevation view of a geometry for defining features of reels and spools made in accordance with the invention; 
           [0066]      FIG. 3  is a schematic diagram of an end elevation view of a spool in accordance with the invention having circumferential corrugations; 
           [0067]      FIG. 4  is a schematic diagram of an end elevation view of a spool and reel geometry illustrating core, sweep and rim angles for a directorix defining a corrugation path for several embodiments of an apparatus in accordance with the invention; 
           [0068]      FIG. 5  is a perspective view of one embodiment of a disassembled reel made in accordance with the invention; 
           [0069]      FIG. 6  is a schematic, side, radial, sectioned view of the reel of  FIG. 5  illustrating both inner and outer corrugation sections; 
           [0070]      FIG. 7  is a cutaway perspective view of one embodiment of a flange in accordance with the invention, having a surface protection layer and curved corrugations; 
           [0071]      FIGS. 8-12  are schematic axial views of flanges made in accordance with the invention and having differing configurations for directorix angles for core, sweep, and rim angles as well as curvature; 
           [0072]      FIG. 12  is a schematic axial view of a flange in accordance with the invention having corrugations of different core angels; 
           [0073]      FIG. 13  is a schematic axial view of a flange in accordance with the invention having two radially distinct regions for providing varying relationships between stiffness and fracture resistance as well as eccentric loading of the flange by tangential corrugations; 
           [0074]      FIG. 14  is a side elevation, sectioned view of reel in accordance with the invention having a radially tapered corrugation and illustrating inner and outer faces thereof; 
           [0075]      FIG. 15  is a schematic sectional view of a radial aspect of a flange in accordance with the invention, illustrating selected embodiments of corrugations; 
           [0076]      FIG. 16  is a schematic sectional view of one half of a radial surface of a flange in accordance with the invention, including spiral and circumferential corrugations, tapered corrugations, and corrugations of constant axial dimension; 
           [0077]      FIG. 17  is a perspective, exploded view of one alternative embodiment of a corrugated reel in accordance with the invention; 
           [0078]      FIG. 18  is a side elevation view of a flange and tube assembly for the apparatus of  FIG. 17 ; 
           [0079]      FIG. 19  is a partial, cut-away, side, elevation, cross-sectional view of one embodiment of the apparatus of  FIG. 17 , configured to promote the use of a folded staple fastening mechanism; 
           [0080]      FIG. 20  is a partial, cut-away, side, elevation, cross-sectional view of one embodiment of the apparatus of  FIG. 17 , configured to promote the use of a bolt; 
           [0081]      FIG. 21  is a perspective, exploded view of one alternative embodiment of a corrugated reel in accordance with the invention; 
           [0082]      FIG. 22  is a side elevation view of a flange and tube assembly for the apparatus of  FIG. 21 ; 
           [0083]      FIG. 23  is a perspective, exploded view of one alternative embodiment of a corrugated reel in accordance with the invention; 
           [0084]      FIG. 24  is a side elevation view of a flange and tube assembly for the apparatus of  FIG. 23 ; 
           [0085]      FIG. 25  is a partially cut-away, side, elevation, cross-sectional view of one alternative embodiment for a flange in the apparatus of  FIG. 23 , illustrating a method for fastening using two tools or a two-prong tool such as a stapler; 
           [0086]      FIGS. 26-28  are end, cross-sectional views of cut-away portions of alternative embodiments of a flange suitable for use in the apparatus of  FIGS. 17 ,  21 , and  23 , relying on molded tab portions associated with a flange, in order to secure a tubular member thereto in various orientations; 
           [0087]      FIG. 29  is a cut-away perspective view of a portion of one embodiment of a flange in accordance with the invention, including multi-dimensional corrugations; 
           [0088]      FIG. 30  is a partially cut-away, cross-sectioned, perspective view of an alternative embodiment of undulating ribs in one embodiment of a flange, also illustrating an alternative or optional closure on a flange base; 
           [0089]      FIGS. 31-38  illustrate alternative embodiments of twin sheet constructions relying on a base and closure to form a flange in at least two pieces, in which the corrugations may run in any combination of radial or circumferential directions; and 
           [0090]      FIG. 39  is a comparison of alternative embodiments of flanges incorporating various twin sheet construction concepts. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0091]    It will be readily understood that the components of the present invention, as generally described and illustrated in the Figures herein, could be arranged and designed in a wide variety of different configurations. Thus, the following more detailed description of the embodiments of the apparatus and methods of the present invention is not intended to limit the scope thereof. Rather, the scope of the invention is as broad as claimed herein. The illustrations merely represent certain, presently preferred embodiments of the invention. Embodiments of the invention will be best understood by reference to the drawings, wherein like parts are designated by like numerals throughout. 
         [0092]    Those of ordinary skill in the art will, of course, appreciate that various modifications to the details of the apparatus and methods illustrated in the Figures may easily be made without departing from the essential characteristics of the invention. Thus, the following description of the Figures is by way of example, and not limitation, and simply illustrates certain presently preferred embodiments consistent with the invention as claimed. 
         [0093]    Referring to  FIG. 1 , an apparatus  10  may be referred to as a spool  10  or reel  10 . The apparatus  10  may include flanges  12 ,  14 , each being provided with a rim  16  and web  18 . The web  18  may extend continuously or discontinuously in a radial, circumferential, axial, or all such, or any combination of such directions. The web  18  extends, whether continuously or periodically (e.g. perforated, spoked, etc.), between a region proximate a tube  20  and the rim  16  near an outermost circumference of a flange  12 . In speaking of flanges  12 ,  14 , in general, a single flange  12  may be referred to, and may be interpreted as including features that may be included in all flanges  12 ,  14 , but need not be necessarily inputted thereto in all embodiments. 
         [0094]    The web  18  extends between the rim  16  and a core  22  or hub  22  near the tube  20  and intended to engage the tube  20  in certain presently preferred embodiments. In other embodiments, the tube  20  may be formed in parts integrated with respected flanges  12 ,  14 , and bonded or otherwise fastened to form the tube  20  as an integrated portion of a single-piece spool. 
         [0095]    As a practical matter, a cap  23  may be positioned as part of the core  22  or applied thereto in order to seal, space, or otherwise serve the flange  12 . For example, the cap  23  may be a portion of the external portion of the core  22 . Meanwhile, an interior portion  24  of a core  22  may be tubular in nature, and may include multiple tubes or sleeves for capturing or otherwise engaging the tube  20  extending between the flanges  12 , 14 . 
         [0096]    The cap  23  may be provided in order to provide an aperture  26  for receiving a driver or dog from a machine on which the apparatus  10  may rotate. Other apertures  27 ,  28  may be used for other functions such as starting and tying, respectively, the stranded material (e.g. wire) wrapped about the tube  20  between the flanges  12 , 14 . 
         [0097]    Each flange  12 , 14  may be provided with corrugations  30 . Corrugations  30  may be configured to have cavities  31  on opposite, alternating sides of each respective flange  12 , 14 . The alternating nature of the cavity  31  and the surfaces  29  is somewhat arbitrary. That is, when viewing a flange  12 , 14  from one side, (e.g. axially speaking) the raised portion may be thought of as a surface  29  and the depressed portion may be thought of as a cavity  31 , not withstanding each cavity  31  is defined by a surface  29 . 
         [0098]    An arbor aperture  32  may be sized to rotate freely and support the apparatus  10  on an arbor during delivery from, or wrapping of the contained, stranded material thereon. The arbor aperture  32  may have a surface  33  operating as an arbor bearing  33  for supporting the weight of the apparatus  10  while accommodating friction, wear, and other structural requirements. 
         [0099]    A cavity  34  may be provided as part of the inside portion  24  of a core. Inside refers to the location seen from the same side of a flange  12 ,  14  as the stranded material would occupy. The cavity  34  may receive the tube  20 . Alternatively, a cavity  34  may be corrugated, ribbed, or otherwise filled. In one embodiment, the cavity  34  may be irrelevant. In such an embodiment, a rim  20  may be designed to extend over an outermost diameter of the core  22 , and more particularly an inside portion  24  of a core  22 . As noted, the cavity  34  may simply be an extension of a tube  20  made in two parts, each part integrally formed with its respective flange  12 ,  14 . 
         [0100]    Referring to  FIG. 2 , and to  FIGS. 1-16  generally, an apparatus  10  may include flanges  12 , 14  in which the web  18  extends in a variety of shapes between a rim  16  and a core  22 . In general, the direction of a specific corrugation  30  may extend in any of the directions available. Corrugations  30  may be shaped to appear like spokes  38 , although the specific functionality may be substantially different. 
         [0101]    For example, viewing the flange portion  10  of an apparatus  10  in  FIG. 2 , the core portion  22  may be surrounded by the web  18  extending in a radial direction  44 , having a thickness in an axial direction  46  at any location, and extending circumferentially  48  or in a circumferential direction  48 . The directions radially  44 , axially  46 , and circumferentially  48  may be defined with respect to a center  50  or axis  50  of the apparatus  10 . The arbor aperture  32  may be defined by an arbor radius  52  formed within the cap  23  having a capped radius  54 . 
         [0102]    Each of the corrugations  30  may extend axially, radially, and circumferentially, as needed to connect the core  22  and the rim  16 . The outermost flanged diameter  58  may be thought of as the effective outer diameter of the apparatus  10  and the flange  12 . In one presently preferred embodiment, the thickness  57  of the rim  16  may be substantially, even orders of magnitude, less than the outermost diameter  58 . Thus, the flange radius  59  about the center  50  is substantially the same on either side of the rim  16 , in such a circumstance. 
         [0103]    In certain embodiments, the rim  57  may not exist other than to be the edge of the flange  12 . However, in keeping with structural mechanics factors, a rim  16  may extend axially away from a surface  29  of a web  18 . In certain embodiments, the surface  29  may be flush with the rim  16 , axially. In other embodiments, the rim  16  may extend axially away from the surface  29  beyond that amount needed to define the cavity  31  with respect thereto. 
         [0104]    In certain selected embodiments, a flange  12  may be formed to have a core region  62  of the web  18  extending a portion of the flange radius  59  away from the core  22  (hub  22 , cap  23 , etc.). The remainder of the radius  59  may be covered by a rim region  64  of the flange  12  as illustrated by a generic flange portion  40 . The rim region  64  of a web  18  is distinct from the rim  16 . A rim  16  may typically extend orthogonally away from a surface  65  defining the web  18 . 
         [0105]    Thus, a core region  62  is that portion of a flange  12  and specifically of the web  18  of a flange  12  extending between a core  22  and some detectable or significant transition portion  60  or transition  60  of the web  18 . Between the rim  16  and the transition  60  extends the rim portion of the web  18  of the flange  12 . The transition  60  may be positioned anywhere desired for improving the structural integrity of a flange  12 . Meanwhile, in general, a spool  10  or a reel  10  may be manufactured with or without any of the apertures  26 ,  27 ,  28 ,  32  as determined to be suitable for the apparatus  10 . 
         [0106]    The significance of the transition  60 , which may be a mathematical circle or other geometry as well as a region having some radial dimension that is not insignificant, is for providing differing balances of strength, weight, stiffness, toughness, fracture-resistance, and fracture-susceptibility of the flange  12 . Moreover, the direction of corrugations may change between the core region  62  and the rim region  64 . 
         [0107]    For example, a flange  12  may have corrugations  30  extending in a completely or substantially radial direction. A flange  12  may have corrugations  30  forming the web  18  and extending exclusively in a circumferential direction. Alternatively, the flange  12  may have corrugations  30  having a circumferentially curving aspect extending between the core  22  and the rim  16  continuously or discontinuously. In one embodiment, both curved and straight corrugations may exist in a single flange. In certain embodiments, certain types of corrugations  30  may be disposed in the core region  62  of the flange  12  as compared with corrugations  30  in the rim portion  64  of the flange  12 . 
         [0108]    Moreover, the rim portion  64  may be designed to promote or resist crushing, fracture, resilience, etc. The core region  64  may be designed to resist or promote deflection, distortion, crushing, fracture, or the like. However, in one presently preferred embodiment, the core  22  must not be completely separable from the core region  62  of the flange  12 . Thus, the material characteristics of the rim region  64  and the core region  62  of the flange  12  may be designed to absorb shock, fracture, distortion, energy, and so forth without improper failures. Catastrophic failure (being rendered unusable, complete separation, rendering useless, etc.) of an apparatus  10  is to be avoided. 
         [0109]    Nevertheless, spools  10  and reels  10  are dropped periodically. Such drops should be accommodated by a selected design for a flange  12 . Accordingly, the generic flange portion  40  illustrates the transition  60  in a dashed circle indicating that it may or may not exist and it may be moved radially inward or outward. Similarly, the rim  16  is delimited by the outermost diameter  58  and a dashed circle interior thereto indicating that the construction, thickness, and even existence of a rim  16  are design parameters that may be traded off against other considerations. 
         [0110]    Thus, in general, a spool  10  or reel  10  may have a flange portion  40  of a flange  12  designed to optimize the performance of the apparatus  10  by a combination of structural stiffness, toughness, strength, weakness, distortion, energy absorption, selective fracture, and so forth. 
         [0111]    Referring to  FIG. 3 , an apparatus  10  may have corrugations  66 ,  67 ,  68 ,  69  extending in a circumferential direction  48 . A web  18  of a flange  12  may have numerous corrugations  30 . The corrugations may be disposed to have alternating surfaces  29  and cavities  31 . The extent in a radial direction  44  of any cavity  31  or surface  29  may be selected by a designer. Nevertheless, one may note that circumferential corrugations  66 - 69  may reduce the probability of transmitting a shock load directly from the rim  16  to the core  22 . 
         [0112]    Substantial fracture of the core  22  causing separation from the core  22  from the web  18  over more than about a third of the circumference of a core, will typically be regarded as a catastrophic failure. A fracture extent of half or more often releases the wire thereon. Accordingly, some mechanism for absorbing shock loads applied to a rim  16  by a drop of a spool  10  or a reel  10  resulting in an impact of a rim  16 , may profitably be accommodated by eliminating or reducing the probability of catastrophic failure between the core  22  and the web  18  from shear, bending, or the like. 
         [0113]    The rim  16  has a substantially larger aspect (size, radius, etc.) than does the core  22 . Accordingly, less material is typically available to support a force transmitted between the web  18  and the core  22  than is available to absorb a radial or bending shock at the rim  16 . Moreover, the bending moment of an axial component of a load at a rim  16  is substantially greater at the core  22  than at the rim  16 . 
         [0114]    Several factors may be accommodated in a design. However, stress levels may be far higher at any interface between the core  22  and the web  18 , for a flange  12  having a constant thickness everywhere, as is good design practice for certain methods of plastics manufacture. 
         [0115]    Referring to  FIG. 4 , and still referring generally to  FIGS. 1-16 , corrugations  30  or a particular surface  19 ,  29 ,  31  extending substantially, radially, or to some extent radially to a substantial amount of its traverse or extent, may be defined or described by a directorix  70 . Thus, a directorix  70   a,    70   b,    70   c,    70   d,    70   e,    70   f,    70   g,    70   h,  may be regarded as a defining curvature for a selected wall  19  or connector  19  portion of a corrugation  30 . One may think of a connector  19  or a wall  19  as that portion of a corrugation  30  extending from a surface  29  to the bottom of a cavity  31 . Thus, a corrugation may extend principally in a radial direction  44 , a circumferential direction  48 , or both, while a connector  19  or a wall  19  will extend principally in an axial direction  46 , and radial direction  44  to connect adjacent corrugations  30 . 
         [0116]    Each directorix  70  may have several features. Controls  72 ,  74 ,  75 ,  76  illustrate certain controlling features for defining the shape of a directorix  70  and its traverse between a core  22  and a rim  16 . The traverse of a directorix  70  may be defined in terms of a core angle  80 , a sweep angle  74 , and a rim angle  76 . The core angle  72  may be defined with respect to a directorix  70  and a tangent  78  to the core  22 . A rim angle  84  may be defined with respect to a tangent  78  and a directorix  70 . A sweep angle  82  may be defined in terms of a difference between a tangent  85   a  to a directorix  70  at a core contact point  81  and a tangent  85   b  to the same directorix  70  at a rim contact point  83 . 
         [0117]    Alternatively, a sweep angle  82  may be defined as a difference between a circumferential position of a core contact point  81  and a rim contact point  83  associated with a single directorix  70  of a corrugation  30  traversing between a core  22  and a rim  16  along a web  18 . The latter definition may provide insights into how much of a web  18  has been traversed by a directorix  70  (e.g. by a wall  19  of a corrugation  18  defined by a directorix  70 ) in a circumferential direction. Adjacent walls  19  connected by a particular corrugation  30  may have different shapes, and thus more than one directorix  70  to define them. 
         [0118]    In  FIG. 4 , the former definition of a sweep angle is used as illustrated in control  75 . The latter definition of sweep angle  82  is used in the control  74 . Each of the flanges in the controls A, B, C, D, E, F, G, H, I, J uses the former definition for sweep angle  82 . 
         [0119]    In general, a directorix  70  may be straight or curved. A directorix  70  may or may not include an inflection point  89  as illustrated in the directorix  70   e  of control E in  FIG. 4 . In certain embodiments, normals  79   a  with respect to a tangent  78  to the core  22 , and normals  79   b  with respect to the rim tangent  86  may be used to define sweeps  82  and other geometric features of any directorix  70  of a flange  12 . 
         [0120]    In general, a directorix  70 , and thus the corresponding wall  90  contacting a core  22  or rim  16  at a core angle  80  or rim angle  84 , respectively, will affect the stress and stress concentration at the core contact point  81  or rim contact point  83 , respectively. One may note that a directorix  70  approaching a core  22  fully tangent thereto may promote stress concentrations at an interior region  77   a,  while reducing them at an exterior region  77   b  with respect to the core  22  and directorix  70  (see control B, control C, and controls  72 ,  76 ). 
         [0121]    The point of designing and controlling a core angle  80 , sweep angle  82 , and rim angle  84  is to control structural design elements that may thereby control the localization of distortion, stress, fracture, toughness, and so forth in a flange  12 , and particularly at those locations where the web  18  of a flange  12  contacts a core  22  or a rim  16 . 
         [0122]    One may think of a stress concentration, such as that which may arise in a region  77   a , as an invitation to structural failure locally. One may think of a smooth transition such as may occur in a region  77   b  as promoting structural integrity by removing the directionality of forces that may tend to rupture the integrity of a flange between a directorix  70  (actually the wall  19  defined by the directorix  70 ) and the core  22 . 
         [0123]    Accordingly, a directorix  70  may be designed to promote failure in an interior region  77   a  or a corrugation wall breaking away from a core  20 . Meanwhile, the same directorix  70  may promote structural integrity with the core  22  at an exterior region  77   b  or on a axially oppositely disposed corrugated wall. Thus, during impact, a directorix  70 , meaning a wall  19  defined thereby, may selectively fracture and separate at distinct locations with respect to a core  22 , while others remain integral. 
         [0124]    In  FIGS. 1-16  several, substantially orthogonal surfaces result from the use of corrugations  30  in flanges  12 . Accordingly, orthogonal surfaces may flex with respect to one another if not stiffened by a third mutually orthogonal surface. A separation of two surfaces may affect orthogonal surfaces until flexure becomes available to a last connecting surface. A combination of a portion of a core  22  maintaining its structural integrity with respect to a wall  19  (e.g. directorix  70 ) may maintain a structural contact between each surface  29 , associated connecting wall  19 , core  22 , the cap  23 , and any combination thereof. At the same time, the same corrugation  30  may selectively fracture with respect to the core  22  at a somewhat different location. Typically a wall-thickness away or more from the integral portion, to absorb the energy of impact. Nevertheless, the integral portion and transferring loads away then maintains sufficient structural integrity of the web  18  and of the entire flange  12  to prevent loss of the contained, stranded material held by the apparatus  10 . 
         [0125]    One may note that a directorix  70 , such as a directorix  70   a  that is normal to the core tangent  78  and the rim tangent  86  will typically transfer impact loads directly to the cores  22  from the rim  16  in a radial direction  44 . By contrast, a directorix  70 , such as a directorix  70   b  may still deliver impact loads from a rim  16  to a core  22 , radially eccentrically, or in bending with additional torsion outside of an axial-radial plane. Likewise, a directorix  70 , such as a directorix  70   c,    70   d,    70   e,    70   f,    70   g  may not have a straight line path in a radial direction between a rim  16  and a core  22 . 
         [0126]    Web  18  may transfer loads through the wall  29 ,  31  (exterior or interior surfaces  29 ,  31  of corrugations  30 ). Stiffening is not readily available from the connector  19  (wall  19 , directorix  70 ) to transmit radial loads. Nevertheless, the connector  19  may be available to provide stiffness against excessive column buckling, shell buckling or distortion, and the like in a radial direction. Bending may be resisted more by radially direct walls  19 . Accordingly, the core angle  80 , sweep angle  82 , rim angle  84 , number of corrugations  30 , thicknesses thereof, and the like, may be designed to promote a selected amount of local distortion, fracture, integrity, toughness, and stiffness, and so forth within the web  18  and flange  12  generally. 
         [0127]    Perforations within the web  18  may be used selectively to promote increased or reduced stress. For example, perforations may be provided at an interior region  77   a  to promote fracture while continuous material may provide the web  18  in a wall  29  of a corrugation  30  in the region  77   b  exterior to a core contact point  81 . In one presently preferred embodiment, a bending load may fracture a corrugation  30 , but each corrugation is circumferentially discontinuous at any axial position. Thus, a corrugation may part radially and axially from a core  22  along a circumferential crack at or near the core  22 . 
         [0128]    A corrugation  30  axially opposite an adjacent fractured one, will not then experience a bending load effective to separate it from the core at the circumferential location. Core angles  80  and circumferential discontinuity of corrugations tend to control the direction of cracks, precluding extensive propagation circumferentially. Thus, a continuous crack will not propagate around the core  22  circumferentially  48 . The core  22  remains attached to the web  18 . Moreover, the corrugations provide structural strength and stiffness in three dimensions, preventing failure of the flange  12  in service. 
         [0129]    Referring to  FIG. 5 , an elevated surface  90  and a flush surface  92  or recessed surface  92  may be thought of as the surfaces themselves, or the entire walls in such locations. One may note that the flush wall  92  or the recessed wall  92 , when viewed axially from outside a flange  12  provides a contact surface  92  for supporting stranded material to be wound on a tube  20 . Accordingly, one may design the corrugations  30  such that any pair of adjacent connector walls  19  within a single corrugation  30  are spaced to promote greater circumferential distance  48  (see  FIGS. 2-3 ) than that for an elevated or exterior wall  90 . 
         [0130]    Thus, the clear span  93  of wire crossing a corrugation  30  associated with an exterior wall  90  may be minimized. Alternatively, a cover  120 , such as a paper board, or inexpensive material not integral with a flange  12  (see  FIG. 7 ), may be provided to reduce bulging or pulling of stranded materials axially  46  into a cavity  31 , interior to a particular corrugation  30 . 
         [0131]    A length  94  of a tube  20  may selected in accordance with a thickness  96  required to support the stranded material on a tube  20 . Accordingly, the ends  98  of the tube  20  may be fitted to a slot  100  designed to support the tube  20  of the associated length  94 , when fully loaded with product (stranded material), in a drop test or in an accident during operation. The core wall  102  may be designed to bond or fasten to the tube  20  in a manner calculated to maintain sufficient integrity between the tube  20  and the flange  12 ,  14  during a drop, thereafter. 
         [0132]    In order to provide minimum weight, minimum wall thicknesses, and the like for each flange  12 ,  14 , a core sleeve  104  may be designed to support the ends  98  of the tube  20 . For example, less material is available to take the force of impact at the core  22 . Accordingly, additional support about the slot  100  may be provided by a core sleeve  104  extending inside a tube  20 , as well as the core wall  102  extending over the outside surface of the end  98 . 
         [0133]    A bearing surface  106  may be formed to extend axially away from the cap  23  of a core  22 . Thus, less material may be used and wall thicknesses may be maintained at a constant value while providing additional bearing surface  106  to reduce friction and maintain integrity of the cap  23 . In large reels, typically greater than one foot in diameter  58 , and often several feet in diameter, the bearing surface  106  or bearing wall  106  (e.g. bearing  33 ) may be a critical design feature for suitable life of an apparatus  10 . 
         [0134]    As a practical matter, struts  108  may be provided inside a core  22 . In one embodiment, corrugations  30  may extend to the arbor aperture  32 . For example, the sleeve  104  may exist and extend axially away from the web  18  to receive the tube  20 . Alternatively, struts  108  may be sized to permit the core  22  to receive the tube  20  therein. Nevertheless, in one presently preferred embodiment, large reels  10  may have a slot  100  formed between a core wall  102  and a core sleeve  104 . In this latter embodiment, the struts  108  may be of any dimension desired consistent with those of the sleeve  104 . 
         [0135]    Referring to  FIGS. 6-7 , and continuing to refer to the remaining  FIGS. 1-16 , a flange  12  of a spool or reel  10  may be provided with an inside face  110  (e.g. see also surface, faces, walls, etc. including walls  90 ,  92 , and  29 ,  31 ). In the embodiment of  FIG. 6 , the inside face of a wall  111  of a corrugation  30  may be opposed to an outside face  112  thereof. Thus, an inside face  110  may be any face that is exposed to the interior of a spool  10  or a flange  10  while an exterior face  110  may be any surface exposed to an environment external to the portion of the spool  10  or reel  10  supporting or containing the stranded material. Thus, a cavity  31   a  may have an exterior surface  112  corresponding to the cavity surface  31  of  FIG. 1 . 
         [0136]    Meanwhile, the same corrugation  30   a  may have an interior surface  110  corresponding to an elevated surface  90  or outer wall  29 , depending on one&#39;s perspective. Thus, one may speak of a wall  111  of a corrugation  30  sharing or connecting to an adjacent wall  111  of an adjacent corrugation  30  by a connector  19  or connecting wall  19 . Thus, for example, a wall  111   a  of a corrugation  30   a  forming a cavity  31  a may share a connecting wall  19   ab  with a wall  111   b  of a corrugation  30   b.  Similarly, the wall  111   a  may share a connecting wall  19   ac  with a wall  111   c  of a corrugation  30   c.    
         [0137]    One may note that the region  77   a  of  FIG. 7  may form a sharp angle and a stress concentration between the connecting wall  19   ac  and the core wall  102  of the core  22 . Meanwhile, the region  77   b  is completely smooth or may be so designed for the connecting wall  19   ab  of the same corrugation  30   a.  Accordingly, for a radial load in tension, fracture may be anticipated in an area  77   a  before fracture in an area  77   b.  However, in bending, the web  18  may fracture along a line between  77   a  and  77   b  at maximum stress, but not usually at the same radial location on an adjacent corrugation  30   b,    30   c  of opposite sense (inside/outside), which is acting as a fulcrum for the fracturing process. Connecting walls  19  may fracture partially or completely in an axial direction toward a fulcrum (e.g. regions between  77   a  and  77   b  for corrugations  30   b,    30   c ). 
         [0138]    One may also note however, that the cavity  31   a  also has various relationships with both the corrugation  30   a  and the corrugation  30   b.  Accordingly, the connecting wall  19   ab  within the cavity  31   a  may also have equivalent locations having the same geometry as the areas  77   a  and  77   b  for the corrugation  30   a.    
         [0139]    However, such interior  77   a  and exterior  77   b  connecting regions will have an opposite sense on opposite sides of the respective walls  19   ac  and  19   ab , and with respect to the adjacent and corresponding corrugations  30   c,    30   b,  respectively. Thus, upon impact, a fracture may occur, partially separating a wall  111   a  from a core  22 , beginning at an area  77   a  and extending along the core  22  or the wall  102  of the core  22  toward the area  77   b . However, adjacency of corrugations  30  may prevent extensive propagation circumferentially of any crack. 
         [0140]    However, the wall  19   ab  may tend to fracture away from the core  22  within the cavity  31   a  . The corrugation  30  opposite a fractured one is acting as a fulcrum for fracture, yet maintaining its own integrity with the core  22  and particularly the core wall  102  in the area  77   b.  Thus, one may see that the dimensions of the corrugations  30  allow great design flexibility. 
         [0141]    An inside face  110  of a wall  111  may be disposed opposite an outside face  112  thereof. The inside face  110  and the inside face and outside face  112  may exist for every wall  111 , regardless of the disposition of the wall  111 , on the inside  113  of the flange thickness  114 , or on the outside  115  of the flange  12 . The inside  113  direction may be thought of as the region of the spool  10  or reel  10  that holds the stranded material (e.g. wire). 
         [0142]    Thus, the cavity depth  95  and the wall thickness  118  may typically add up to the flange thickness  114 . Nevertheless, the flange thickness  114  need not be constant in a radial direction  44 . Similarly, a wall thickness  118  need not be uniform in a radial direction  44  or a circumferential direction  48  but may be adapted to absorb or sustain loads. Nevertheless, constant wall thickness at all locations tends to promote uniformity of stress and reliable manufacture at consistent molding times for plastics. 
         [0143]    Extending in a radial direction  44 , a corrugation  30  may be tapered in order to reduce weight, balance forces, permit selected distortion, or provide more uniform impact loading, For example, near the rim  16 , more material exists in a circumferential direction  48  to absorb loading, breakage, distortion, and the like as a result of shock loads (forces, impact) when compared with a location near or at the core wall  102 . 
         [0144]    Moreover, the bending moment on a flange  12  is greatest near the core  22  in response to a load applied near the rim  16 . Thus, a tapered flange  12  having a narrower flange thickness  114  near the rim  12  may provide a closer balance or more uniform distribution of forces in the flange  12 . On the other hand, selective fracture may be designed into various corrugations, as a result of a uniform flange thickness  114 , thus focusing energy at the core  22  as it interfaces with the web  18  (e.g. walls  111  and connector walls  119 .) 
         [0145]    Referring to  FIG. 7 , one may note that a point  132  along a connector wall  19   ac  is one type of core contact point  81  or core contact line  81  for a directorix  19   ac  or connector wall  19   ac . Similarly, for the corrugation  30   a,  the core contact line  81  or core contact point  81  is identified by the point or line  130  of tangency of the connector wall  19   ab  with the core wall  102 . Thus, adjacent connector walls  19   ac ,  19   ab  operate similarly. Nevertheless, with respect to any particular corrugation  30   c,    30   a,  respectively, the connector walls  19   ac ,  19   ab  respectively, will behave differently with respect to their own individual interior  77   a  and exterior  77   b  angles at their respective contact points  132 ,  130  or contact lines  132 ,  130 . 
         [0146]    Each connecting wall  19  may have one or more radii of curvature  124  about one or more centers  126  or center points  126 . That is, the radius  124  may not be constant. Moreover, the center point  126  may not be constant. Nevertheless, in one embodiment a uniform radius  124  about a single center  126  may be selected for each connector wall  19 . The design patterns  72 - 76  and A-G of  FIG. 4  illustrate selected samples of connector walls  19 , as a directorix  70 , in each case. Thus, the corrugations  30  of the flange  12  of  FIG. 7  may be formed as a variation of the control D or pattern D of  FIG. 4 . 
         [0147]    Nevertheless, the flange of  FIG. 7  may be designed to have any combination, or all combinations, or some other combinations of core angle  80 , sweep angle  82 , and rim angle  84 , as well as inflection points  89  and one or more radii  124  of curvature about one or more centers  126  of curvature. Moreover, the relative proportion of the inner face  110  of the web  18 , as compared with the outer face  112  of various corrugations  30  may be adjusted to provide more or less stiffness or distortion. 
         [0148]    For example, if the width  133  of a corrugation  30  (e.g.  30   a ) is comparatively larger than the same dimension  133  of an adjacent corrugation  30  (e.g.  30   b,    30   c ), at any given distance  131  or radius  131  from a central axis  50  of a flange  12 , distortion may be effected. Moreover, the clear span  93  between adjacent internal corrugations  30  (e.g. on the inside face of the flange  12 ) may be reduced. The walls  111   a  having a larger dimension  133  may be more susceptible to distortion in an axial direction or a radial direction upon impact. 
         [0149]    Accordingly, non-uniform stiffness within adjacent walls  111 , corresponding to adjacent corrugations  30 , may provide absorption of energy without failure of the fundamental structure of the flange. Nevertheless, the corrugations  30  may prevent catastrophic failure with an appropriate amount of relative stiffness where needed. Corrugations  30  having a comparatively narrower width  133  may be designed to bend or spring by virtue of having an aspect ratio closer to a value of one. 
         [0150]    An aspect ratio may be thought of as the ratio of depth  95  of a cavity  31  with respect to a span  133  or width  133  of a single corrugation  30  at a particular radius  131 . Thus, for example, interior walls  111  in contact with stranded material may have comparatively larger widths  133  than exterior walls  111  not in contact with the stranded material. Moreover, provision of a sharp angle near the transition from a connector wall  19  to a corrugation wall  111  may promote selective fracture, allowing a corrugation  30  to spring separately from its adjacent corrugation. Thus, selective local failure or separation may actually protect the overall integrity of the flange  12  under impact or shock loading. 
         [0151]    Stress concentration inhibition may be provided by fillets in selective corners. Increased stress concentration factors may be provided by sharpening the angle between connected, especially orthogonal, surfaces. Fillets need not be constant along the entire length of a directorix  70  (connector wall  95 ). 
         [0152]    In one embodiment, a corrugation  30  may be formed to have a comparatively sharper angle between a wall  111  and one of the adjacent connecting walls  19  with a comparatively more rounded transition between the same wall  111  and its opposite connecting wall  19 . Thus, one connecting wall  19  will remain with one corrugation  30 , while the adjacent connecting wall  19  will remain integral with the wall  111  of the next corrugation  30 . 
         [0153]    For example, a corrugation  30   a  may remain integral with the connecting wall  19   ac , by virtue of proper location of fillets, while separating from the connector wall  19   ab  due to an absence or sharpness of fillets. Similarly, the corrugation  30   b  or  30   c  may provide selective breakage and selective integrity in order to absorb more shock with distortion and breakage. 
         [0154]    Breakage absorbs tremendous amounts of energy. Selective breakage may absorb energy of impact in areas where the contained wire or other stranded material on a tube  20  of a reel  10  or spool  10  will not be damaged or rendered unusable or inaccessible. 
         [0155]    If the connector walls  19  of the corrugations  30  of  FIG. 7  are straightened in accordance with other designs illustrated in  FIG. 4  or similar thereto, impact loads may be delivered directly from the rim  16  to the core  22 . Accordingly, breakage may occur between the corrugations  30  and the core  22 . Whereas the apparatus of  FIG. 7  may provide eccentric loading on the core  22 , reducing, absorbing, or eliminating much of the radially directed energy from the corrugations  30  to the core  22 , a straight connector wall connected normal to a core tangent  78 , may fracture from the core  22  at the core wall  102  or in the web  18 . However, as with bending loads, once fracture occurs, a corrugation can both re-distribute loads through the web  18  and resist further failure due to its shape. A comparatively longer core wall  102  (as compared with corrugation  30  thickness  114  axially) may act as a cantilevered “barrel stave,” flexing radially but not failing axially at all locations. 
         [0156]    Again, in selected embodiments, one connector wall  19  corresponding to an individual corrugation  30  may have a core angle  80  close to perpendicular. Impact may cause shearing of the core  22  or web  18  and breakage. Meanwhile, an adjacent connector wall  19  may be curved or positioned eccentrically, tangent, or the like, with respect to the core  22  or a core tangent  78 . 
         [0157]    The wall  19  may permit torsional distortion in one or more directions  44 ,  46 ,  48 . Accordingly, fracture may be reduced or eliminated for such a connector wall  19 . Thus, both fracture and toughness may be provided for absorbing impact without destroying the entire structural integrity of a corrugation  30 . In certain embodiments, adjacent corrugations  30 , meaning in this context adjacent and on the same side (e.g. inside or outside) of the flange  12 , may be disposed closer together and alternating in their impact resistance and toughness characteristics). 
         [0158]    Referring to  FIG. 8 , specifically, and to  FIGS. 7-14 , generally, a core  22  may be formed flush with an outer face  112  of a corrugation wall  111 . A cap  23  may form a fixed end axially beyond, or flush with, the exterior surfaces  112  or outer faces  112  of the various corrugations  30 . 
         [0159]    A corrugation  134  and an adjacent corrugation  136  may share a connector wall  135 , a specific instance of a wall  19 . Thus, the cavity  31  of the corrugation  136  is closed on only four sides and has a single open side. By contrast, the flanges  12  of  FIGS. 1 and 5  have five sides. 
         [0160]    Accordingly, the corrugations  30 ,  134 , 136  may be considered highly triangulated. Triangular shapes tend to be particularly rigid. Nevertheless, in view of the formation of contact areas  138  or connection areas  138 , the corrugation  134  may transition within a single surface  112  to the cap  23  of the core  22 . A corrugation  134  may tend to continue fracture and reduce or eliminate integrity between the portions of the web  18 , or between the web  18  and core  22 . However, all fracturing beginning in the corner  77   a  and proceeding circumferentially  48  a limited distance due to the circumferential discontinuity of material. 
         [0161]    Fracture beginning in the corner  77   a  or stress-concentrating region  77   a  does not become equivalent for the corrugations  134  and  136 . A corrugation  134  shares the cap  23  of the core  22 , or shares a surface with the cap  23 . By contrast, the region  77   a  does not have a surface on the inside  113  of the flange  12 . A fracture may be propagated through the face  112  from the region  77   a,  toward the corrugation  136 , across the corrugation  134 . Loading may fracture corrugations  30  from cores  22 . In bending, a more likely event is the fracture of a connector wall  135  under the force from one corrugation  134  ( 136 ) acting as a fulcrum and the other  136  ( 134 ) separating completely or partially from the core  22 . The structural strength and stiffness of the web  18  may then redistribute loading even when partially separated from the core  22  by failure under bearing loads. The web  18  remains attached to the corrugation  134  and functional. 
         [0162]    The contact region  141  under a fulcrum region of a corrugation  134  appears structurally to be continuation of the connector wall  135 . Bending may be axially inward or outward and corrugations  30  do not generally fracture the same on axially opposite sides of a flange  12 , nor in exactly the same defections. Thus overall integrity of the webs  18 , and of spools  10  or reels  10  (core  22  to web  18 ) is excellent. 
         [0163]    Fracture beginning through the region  138  and beginning at the corner  77   a  across the corrugation  134 , once started, may tend to propagate orthogonally though the core wall  102  (not seen, see  FIGS. 5-7 ), depending on core wall thickness  102 . Alternatively, cracks may propagate orthogonally along connecting walls  19 ,  135 . 
         [0164]    No flush surface is available between the core  22  and the corrugation  137  to carry a fracture circumferentially, and continuously in a single direction. However, in bending, tearing or fracturing of connecting surface  135  from the core  22  can occur. Likewise, all fracture need not occur at a core  22 , but may occur radially away therefrom. 
         [0165]    An extended length of a core  22  protruding axially in an inward direction  113  (see  FIGS. 6 ) from the corner  77   a  through the corrugation  137  may propagate only so far as distortion will allow and necessitate as loads are re-distributed. 
         [0166]    Depending on the load directions, a portion of a core wall  102  may connect to the corrugation  137 , and may not completely sever the connecting wall  19  away from the corrugation  134 . Selected fracture can occur from incipient points  77   a  in corrugations  137 , but not from the same drop or the same bending load, typically. 
         [0167]    The contact regions between a cap  23  and a corrugation  134  may tend to fracture about a core wall  102 . Similarly, in a next corrugation  136 , the region  141  may tend to be integral. A region  139  may tend to fracture, separating the outer face  112  of a corrugation  30  from the rim wall  102 . Thus, the region  141  may maintain its integrity with the web  18  and rim  22 , but typically in a drop or impact of an axially opposite sense, just as the corrugation  134  may. Thus, the corrugation  134  may tend to maintain integrity by reliance on the corrugations  136 ,  137  and the shared connector walls  19 ,  135 . 
         [0168]    Each of the corrugations  30  (e.g.  30   a,    30   b,    134 ,  136 ,  137 ) may have a fracture region  138  or a contact region  138  with the cap  23 , which region  138  may fracture. A core contact region  140  may remain intact but orthogonal thereto as an extension of a connecting wall  19 . Substantial loading may be remotely supported by the corrugations  30 . The regions  138  may be thought of as the fracture regions wherein a corrugation  30  (e.g.  30   a,    30   b,    134 ,  136 ,  137 ) separates from the core  22  or itself. A region  139 , 140  may be viewed as an area where a connector wall  19  maintains integrity with the core wall  102  orthogonal to a rupturing corrugation face  112 . In opposite bending, roles of corrugations may reverse. 
         [0169]    Rupture may propagate circumferentially across a corrugation  30 , radially through a core wall  102 , segmenting the core  22  circumferentially, if the wall  102  is comparatively thin. In the latter event, cantilevered portions may extend axially parallel to one another. Maintaining a certain portion of the core  22  near the flange web  18  free from rigid adherence to a tube  20  may promote greater durability. For example, a cardboard tube  20  tends to have great toughness, not failing in very high loadings, and most drop tests. Meanwhile, a core  22  may be able to flex substantially between axial breaks propagated from sharp corners  77   a  across outer surfaces  112 . Thickness design can control fracture. 
         [0170]    Due to the nature of stress concentrations, fractures may begin in corners  77   a  and propagate radially through core walls  102 , but may be substantially less likely to propagate to or beyond a connector wall  135 . Whether fulcrumed in bending of flanges  12 , or stripped into slatted staves by a radially and axially directed fracture sympathetic to the fractured region  138  circumferentially from a corner  77   a,  adjacent corrugations  134 ,  137  can survive and support one another. 
         [0171]    Substantial loads can be re-distributed and transferred through corrugations  30  after a fracture almost anywhere between a rim  16  and a core  22 . Nevertheless, the comparatively rigid triangulation of a corrugation  30  may tend to break near the core in bending. Radial components of forces may tend to rotate the core  22 , or resolve forces into an eccentric, tangential load applied to, the core  22  and attached tube  20 . 
         [0172]    Other dimensions of a flange  12 , and particularly of individual corrugations  30 , may be designed to crush, fracture, distort, or hold. An interior corrugation  142  may be provided with a start hole  27  for wire. The start hole  27  may be positioned to relieve stress, or to propagate or to initiate fracture in a selected region. Thus, various start holes  27  (for starting wire wrap) or small stress-relief apertures  27  may be disposed periodically about a flange  12 . 
         [0173]    A rim wall  144  may extend axially  46  to any desired flange thickness  114 . A connector wall  146  on an “inner” side of a corrugation  30   a  may maintain its integrity with the core wall  102 . The connector wall  148  may maintain its connection to the core  22  or core wall  102 , but is likely to propagate a fracture toward a corrugation  137  and cavity  31 . Meanwhile, the outer connector wall  148  will likely not maintain its connection with a connector wall  146 , except through the broken, and thus flexible, core  22 , having sympathetic fractures orthogonal to the surfaces  112 . 
         [0174]    Providing a broader width  133   a  in an interior corrugation  136 ,  148  as compared to a width  133   b  of an exterior corrugation  134 ,  149  respectively, may promote distortion in a radial direction  44  with substantial deflection in an axial direction  46  (see e.g.  FIGS. 2-3  for directions). The radius of curvature  124  of  FIG. 7  may be replaced by a comparatively rigid triangular structure directing forces eccentrically toward a core tangent  78  in  FIG. 8 . Bending a flange  12  axially may actually create a torsional component about a radius when corrugations do not run strictly radially  44 . 
         [0175]    A single point  152  may exist for each corrugation  30  of  FIG. 8  (e.g.  134 ,  136 ,  148 ,  149 ,  30   a,    30   b,    142  being specific examples). The single point  152  of  FIG. 8  corresponds to a line  132  extending axially as a contact line  132  or contact point  81  forming a vertex  81  between tangents  78  to the core wall  102  and the connector walls  19  for a particular corrugation  30 . Fileting may relieve all points  152 ,  81 , etc. 
         [0176]    Referring to  FIG. 9 , and continuing to refer to  FIGS. 8-14 , generally, various corrugations  30  (e.g. interior corrugation  136  and exterior corrugation  134 ) may be defined in terms of interior connecting walls  146  and exterior connecting walls  148 . Each connecting wall  146 ,  148  may be defined in terms of one or more radii of curvature  124   a,    124   b , measured from one or more centers of curvature  126   a,    126   b,  respectively. In the embodiment of  FIG. 9 , a rim wall  144  may be continuous, despite the alternating inside and outside corrugations  136 ,  134 , respectively. 
         [0177]    The wall  102  of the core  22 , illustrated in hidden lines, is tangent to the corrugations  30  (e.g.  134 ,  136 ) at particular contact points  152 . The connecting region  138  between the exterior or outer corrugation  134  and the core  22  may operate to be fractured selectively in order to propagate fracture from a point  152 , maintaining selective attachment of connecting walls  146  to the core wall  102 . 
         [0178]    A principal of selective proportioning of the thickness  133   a  of an inner or interior corrugation  130  in contact with the stranded material of the spool  10  or the reel  10  may provide a comparatively narrower thickness  133   b  for an exterior corrugation  134 . This may be particularly effective in an embodiment such as that illustrated for  FIG. 9 . 
         [0179]    Radial forces applied to the rim  16  may be largely resolved into circumferential forces applied to the core wall  102 , with selective fracturing at points  152 , and along connecting walls  148  (optionally), or elsewhere as desired. Bending may resolve into more torsion about a radius instead of a direct axial tension load in the web  18  or at the core  22 . Selecting an aspect ratio for each exterior corrugation  134  in order to approximately equalize axial and circumferential dimensions thereof, may again provide springs, selective fracturing, and selective deflection or distortion, of interior corrugations  136  in contact with the stranded material. 
         [0180]    In general, a completely fracture-proof spool  10  or reel  10  is not necessarily the best. All materials must distort under load. A material or design that is too stiff to accept any distortion must typically fail under less load than a similar design having more flexibility. If sufficient strength can be added to absolutely preclude rupture at operational or accidental impact loads, then selective distortion and fracture may not be required. However, a spool  10  or a reel  10  having a value two orders of magnitude less than the value of stranded material contained thereon, does not bode well for an absolutely fracture proof design. 
         [0181]    Referring to  FIG. 10 , one embodiment of an apparatus  10  may rely on a straight directorix  70  uniform in core angle  80 , sweep angle  82  and rim angle  84  for all corrugations  30  (e.g.  134 ,  136 ) defined thereby. Nevertheless, an interior point  156  or inner point  156  and an exterior point  154  may replace the single point  152  of  FIG. 9 . Moreover, the core  22  is interior with respect to the core angle  80  of every directorix  70 , connecting wall  70 ,  146 ,  148 . 
         [0182]    Note that no directorix  70  or corresponding connecting wall  19  (e.g.  146 ,  148 ) actually exists tangent to either the core  22  or the rim  16 . Nevertheless, sufficient eccentricity exists to operate similarly to the configurations of  FIGS. 8-9 . However, the straight connecting walls  19  (e.g. of which the specific examples  146 ,  148  pertain to corrugation  136 ) tend to stiffen the flange to direct loads in a straight line toward the core from the rim. Again, changing comparative widths  133   a,    133   b  to form larger interior corrugations  136  may be used to promote features here described in association with  FIGS. 6-9 . 
         [0183]    The applicability of perforations, selective filleting, selective stress concentration factors, and the like may be applied at the interior points  156  or exterior points  154  in order to provide preferential fracture in the region  141  and preferential integrity in the region  140 . Moreover, once some amount of fracture has occurred stress may be relieved. Moreover, inasmuch as three orthogonal surfaces appear at each of the corners  152 ,  154 ,  156 , a selective fracture to separate one surface from the other two, may permit flexure between the two remaining orthogonal surfaces. So long as rigidity is maintained, loads must either be supported or materials must be distorted (deflected) or fractured. Once a single surface has been fractured away from the remaining two, at a particular corner  152 ,  154 ,  156 , the flexure of the remaining two orthogonal surfaces may absorb deflection. The energy will have been absorbed by the fracture and being placed on more remote regions by virtue of that flexure. 
         [0184]    One benefit of this design in bending of flanges  12 , is that fracturing may be directed. For example, adjacent corrugations  134 ,  136  will not normally fracture circumferentially at a single radius, even across a single corrugation  134 ,  136 . Corrugations will support one another in failure. More fracture, in more directions, can be absorbed with minimum loss of functional integrity of a flange  12  and spool  10 . 
         [0185]    Referring to  FIG. 11 , a spool  10  or reel  10  may have a flange  12  in which a substantial sweep angle  82  (see  FIG. 4 ) exists. A directorix  70  may define a connecting wall  146  between an exterior corrugation  134  and an interior corrugation  136  recessed to form a cavity  31  in the end of a flange  12 . The point  152  may be designed to operate to fracture. A sufficient sweep angle with an aspect ratio between the thickness  133   b  and the thickness  133   a  much less than one can provide the selective spring, distortion, fracture, and other benefits here to for described, to an even greater degree. Bending survival may be substantially enhanced. Distortion may be traded off against stiffness in radial loading, axial bending, or both, by selection of core angle  80 , sweep angle  82 , and rim angle  84 . Discontinuous fracture may absorb energy, while corrugations transfer loads and retain structural integrity of a flange. 
         [0186]    Thus, more distortion may be provided, even avoiding fracture or excess fracture. Meanwhile, the nature of the transition between the core  22  and any individual corrugation  30  (e.g.  134 , 136 ) may promote regions  141  maintaining mechanical integrity with the core  22 . The adaptability of orthogonal surfaces being reduced from three at a point  152  or corner  152  by fracture to leave only two, may promote uncoupling of absorption of energy through fracture, and distortion of connections through flexure, in order to absorb energy but to avoid catastrophic failure (e.g. separation) and to maintain mechanical integrity. 
         [0187]    Referring to  FIG. 12 , a directorix  70   a  may define a connecting wall  135  between an outer corrugation  134  and an inner corrugation  136 . A load applied radially may still be resolved eccentrically at the core  22 . Nevertheless, a sharp interior corner  156  may be normal to a core tangent  78 , while an exterior corner  154  on the same exterior corrugation  134  may be parallel to a core tangent  78 . A bending load may be resolved into plate distortion and loads in both axial and circumferential directions. Fracture directions may be thus controlled. 
         [0188]    A point  152  may be formed by connecting walls  135 . Nevertheless, selection of the respective dimensions of the exterior corrugations  134  and interior corrugations  136  may leave a space for corners  154 ,  156  in an individual interior corrugation  136  to be separated, analogously to the structure of  FIG. 10 . Numbers, dimensions, and aspect ratios of corrugations  134 ,  136  may be selected in accordance with design choices to balance strength, rigidity, flexibility, distortion, toughness, selective fracture, and so forth as described previously. 
         [0189]    Continuous fracture of the web  18  from the core  22  can be avoided by the directionality of loadings in bending or direct radial impact. Moreover, distortion and stiffness may be balanced against each other in olefinic plastics, while fracture lengths and directions may be balanced against weight and strength in more brittle materials maintaining system integrity. 
         [0190]    Referring to  FIG. 13 , a spool  10  or reel  10  may include a flange  12  having panels  160  disposed interiorly (toward the wire or strand) or exteriorly, alternating therebetween, or in some designed pattern. In the embodiment of  FIG. 13 , the connecting walls  162  are all illustrated as viewable from the exterior as ribs  162 . Nevertheless, the ribs  162  are only so displayed for the sake of clarity. As a practical matter, all of the combinations for recessing or raising individual panels  160  cannot be shown in a single figure. Accordingly, any of the panels  160  may be raised or recessed axially as desired. Thus, the ribs  162  may represent schematically the connecting walls  162  (e.g.  19 ) between adjacent panels  160 . In the embodiment of  FIG. 13 , a core region  62  extends from a core  22  outward to a transition  60 . 
         [0191]    Between the transition  60  or transition region  60  and the rim  16 , defined by a rim wall  13  extending circumferentially  48  and axially  46 , stiffness, toughness, fracture resistance, fracture susceptibility, and the like may be traded off differently than in the core region  62 . Accordingly, the rim region  64  may be designed to have very stiff, thin, fracture-susceptible walls. Thus, in a standard drop test (e.g. from workbench height) a portion of a flange  12  may be bent, crushed, or broken by axial, off-axis, or radial loads near the rim  16  in order to preserve the integrity of connections between the core  22  and the flange  12  in the core region  62 . 
         [0192]    Alternatively, the rim region  64  of the web  18  may be adapted to provided selected distortion and deflection to absorb the energy of impact, up to some pre-designed failure point at which fracture may be precipitated. Nevertheless, in the core region  62 , flexibility, eccentricity, spring response, distortion, and the like as described with respect to other designs herein, may be appropriate. 
         [0193]    The transition regions  60  may be defined by a medial rim  164 . A medial rim  164  may be smooth, or somewhat abrupt, and may be analogous to the outer rim  16  of the flange  12 . Accordingly, specific energy absorption mechanisms may be implemented near the medial rim  164  to mollify the transmission of radial loads toward the core  22  through the core region  62  of the flange  12 . 
         [0194]    The counter-running, connecting walls  162 , tend to stiffen the flange substantially. Uniformly curved, connecting walls  162 , all oriented in a single orientation and distributed circumferentially  48 , may provide more flexibility, and less stiffness, both radially and in bending. The direction or sense of curvature of the connecting walls  162  in the rim region  164  and the connecting walls  135  in the core region  62  may be the same or opposite. Thus, either an inflected or a monotonic curvature or sense of curvature may be provided. 
         [0195]    Referring to  FIG. 14  a spool  10  or a reel  10  may be provided with tapered corrugations  30 . The components of the apparatus of  FIG. 14  correspond to those of  FIG. 6 , but show schematically a variable cavity depth  116  and flange thickness  114 . The flange thickness  114  and cavity depth  116  vary with radial  44  position along the flange  12 . Both outer corrugations  134  and inner corrugations  136  are illustrated in cross section. The larger size of the rim  16  may provide distributed or re-distribution of loads upon localized failure of the web  18  between the rim  16  and the core  22 , as described above. Wider connecting walls  19 ,  135  may absorb more energy of distortion during and preceding fracture, thus protecting a wall  111  opposite one failing in bending. 
         [0196]    Referring to  FIG. 15 . a cross-section of a flange  12 , in accordance with  FIG. 2  may illustrate various aspects of corrugations  30 . For example, a wall  111  of a corrugation  30  may have a uniform or non-uniform pitch  170 . Even with a uniform pitch  170 , the circumferential span  172  within a cavity  31  of a corrugation  30  may be different for interior and exterior corrugations  30 , For example, various patterns  174  (note, herein, that a trailing alphabetical character is simply a specific instance of the leading reference numeral that generically refers to all items of the same type or class) may have various aspect ratios of cavity depth  116  to width  172 . 
         [0197]    An aspect ratio may change dramatically as a cavity width  172  narrows near the core  22  and widens near the rim  16 . By contrast, a cavity depth  116  may be more-or-less constant. However, a non-constant or non-uniform cavity depth  116  may be employed as illustrated in  FIG. 14 . Accordingly, the aspect ratio of a corrugation  30  may change dramatically from a rim having a comparatively large circumferential dimension  172  and the smallest axial dimension  116 . Near the core  22 , the circumferential dimension  172  will be minimized, while the axial cavity depth dimension  116  will be maximized. 
         [0198]    The pattern  174   a  presumes a rectangular or perpendicular relationship between connecting walls  19  and the corresponding corrugation walls  175   a,    175   b.  The description of a wall  111  as an inner wall  175   a  and an outer wall  175   b  is merely for convenience. 
         [0199]    A trapezoidal pattern  174   b  may provide a circumferential span  172  in a cavity  31   a  interior (near the wire) that may or may not be of the same dimension when disposed exterior to the flange (away from the wire). Similarly, a cavity depth  116  may vary circumferentially according to an angle  176  at which a wall  111  extends to form a ramp  177  along a ramp span  178 . The comparative proportion or aspect ratio of both the clear span  172  (clear circumferential span or open circumferential span  172 ) and the cavity depth  116  may be designed for a specific application. 
         [0200]    Moreover, the aspect ratio of open spans  172  corresponding to exterior walls  175   b  and interior walls  175   a  of corrugations  30  may be selected to provide the various benefits defined herein. Thus, that aspect ratio need not be unity. Moreover, the aspect ratio of cavity depth  116  to clear span  172 , or even to the total pitch  170  may be designed to promote structural integrity and energy absorption. Maximum cavity depth  116  may vary from one corrugation  30  to another  30 . In one embodiment, the aspect ratio of cavity depth  116  to clear span  172  for a corrugation  30  corresponding to an exterior wall  175   b  may be of an order of magnitude of one or less. Meanwhile, the angle  176  may typically be adapted between 0 and 90 degrees accordingly. Likewise, the angle  176  will affect the span  178  associated with the ramp portion  177 . 
         [0201]    The pattern  174   c  may take on may of the attributes of the pattern  174   b.  Nevertheless, the pattern  174   c  may be seen as a degenerate form of the pattern  174   b.  The cavities  31  have collapsed (degenerate case) from trapezoids to triangles. Thus, one may compare the inside peak  179   a  corresponding to an interior wall  175   a  to the exterior or outside peak  179   b  corresponding to an interior wall  175   b  of a corrugation  30 . Accordingly, a flange thickness  114  may still be defined for all of the patterns  174 . Nevertheless, less surface area is presented to the stranded material in the design of the pattern  174   c.  Accordingly, stiff, stranded material, may be best adapted to the use of the flanges  12  of the pattern  174   c.    
         [0202]    The pattern  174   d  may be thought of as a non-uniform aspect ratio of the interior cavities  31   a  to exterior cavities  31   b  corresponding to exterior corrugation walls  175   b  and interior corrugation walls  175   a,  respectively. Thus, the span  172   a  divided by the span  172   b  may provide a circumferential aspect ratio for non-uniform corrugations  30 . Likewise, uniform corrugations  30  may have a circumferential aspect ratio of one. That is, at any given radius  131  from a center  50 , the circumferential aspect ratio is one for a uniformly distributed arrangement of corrugations  30  extending substantially radially. Again, the aspect ratio of cavity depth  116  to span  172   a,  as well as the aspect ratio of cavity depth  116  to the exterior or outer span  172   b  may be designed as described hereinabove. 
         [0203]    The pattern  174   e  may be sinusoidal or otherwise curved and inflected as desired. Many of burdens and benefits of the pattern  174   e  correspond to the pattern  174   c.  As a practical matter, the pattern  174   d,  if modified slightly to permit a draft angle (for molding) less radical than the ramp  177  of the pattern  174   b,  may provide an excellent combination of flexure, toughness, stiffness, energy absorption, spring response or resilience and so forth for a flange design. 
         [0204]    Referring to  FIG. 16 , various configurations of flanges  12  are illustrated. In general, each flange extends from a center line  50  a distance  59  or a radius  59  to the outer extremity of a rim  16 . The pattern  180   a  reflects a cross-section cut, radially through half a flange  12 . The pattern  180   a  may reflect the design of  FIG. 3 ,  FIG. 7 ,  FIG. 9 , or  FIG. 11 , in selected embodiments. That is, the walls  111  may extend to provide interior cavities and exterior cavities  31   b . Thus, the corrugations  30  may extend circumferentially, exclusively, or circumferentially and radially as illustrated in  FIGS. 1-14 . A liner  182  may be provided as illustrated in the liner  120  of  FIG. 7 . 
         [0205]    The periodicity of the cavities  31   a,    31   b  in a radial direction  44  may be governed by the frequency or circumferential pitch  170  of a directorix  70  defining corrugations  30 , regularly or irregularly, about the circumference  48  of a flange  12 . Accordingly a liner  182  of paper, or of some other material may be provided to promote or support stranded materials against bulging into the interior cavities  31   a.    
         [0206]    The pattern  180   b  illustrates a tapered corrugation  30 . The corrugations  30  may be tapered regardless of which pattern  174  (see  FIG. 15 ) is used. Similarly, the pattern  180   c  of  FIG. 16  corresponds to a uniform corrugation thickness  114 . 
         [0207]    Referring to  FIGS. 17-18 , the tube  20  may secure two flanges  12 ,  14  in which selected portions may be corrugated. For example, in the embodiment of  FIGS. 17-18 , the core  190  is itself corrugated. The core  190  may be corrugated synchronously with respect to corrugations  30  located outside (radially) of the core  190 . Thus, a recess  192  or cavity  192  corresponding to the core  190  may be juxtaposed radially across a region engaging the tube  20  from a recess  31  corresponding to the corrugation  30  of the outer region  200 . The core  190  may thus be synchronous, having the recesses  192  of the corrugation  191  aligned with, almost as if a continuation of, the recess  31  of a corresponding corrugation  30  in circumferential phase therewith. 
         [0208]    In the embodiment illustrated, a wall  198  connects the web  194  corresponding to the recess  192 , to the web  196  corresponding to the outer surface  193 . In general, however, a corrugation  191  may have any effective cross-section. Thus, an undulating sinusoidal combination of recesses (defined by the inside web  194  or recessed web  194 , with respect to a viewer) and an outside web  196  need not be so angularly defined. 
         [0209]    A sinusoidal shape has a position or displacement along a surface that is continuous. Moreover, a first derivative of that displacement is continuous. However, the first derivative of a rectangular corrugation is discontinuous. Thus, one may speak of the inside web  194  as the portion below or axially away from a viewer, and the outside web  196  as the portion of the sinusoidal shape that is closer to a viewer. 
         [0210]    In a sinusoidal embodiment, one may think of the webs  194 ,  196  as being those portions that are closest to a tangent perpendicular to an axis  46  of flange  12 . The wall  198  may be considered as the location where a tangent would be approximately or most nearly parallel to an axis  46  of the flange  12 . 
         [0211]    Referring to  FIGS. 19-20 , a core  190  and an outer region  200  of a flange  12  may be synchronous, and thus provide an alignment region  210 . In an alignment region  210 , access is available on both sides of a tube  20  (e.g. wall thereof) in order to position a fastener  212  therethrough. In the embodiment of  FIG. 19 , the fastener  212  is a staple, and the embodiment of  FIG. 20  illustrates a bolt. A screw, a rivet, or other fastener as described herein may be suitably engaged to secure the tube  20  to the flange  12 . Moreover, the fastener  212  may be installed by a double-pronged device in which the fastener  212  can be accessed on either or both sides of the wall of the tube  20 . In this manner, a rivet or staple  212  is a possible fastener. 
         [0212]    In general, access is only needed from either the cavity  192  of the corrugation of the core  190 , or from the cavity  31  of the corrugation  30  of the outer region  200 . Such an access would result in a tacking approach. For example, a screw, a staple that is not folded, or the like might be used in such a situation. However, in order to fasten a bolt  214  or fold a staple  212 , access from both cavities  31 ,  192  may be provided by fabricating the flange  12  with synchronous corrugations  30 ,  191  in order to provide the region of alignment  210 . 
         [0213]    Referring to  FIG. 20 , the concept of synchronizing or leaving unsynchronized (asynchronous) the core  190  and the outer region  200  may be implemented in fabrication of the flange  12 , as a single piece, (e.g. homogeneously molded), or by fabricating the flange  12  from distinct pieces  190 ,  200 . For example, if the core  190  is distinct, divided from the outer portion  200  by a parting line  216 , then the fastener  212  effectively assembles or fastens the core  190  to the outer portion  200 . Accordingly, the core  190  may be rotated to be synchronous or asynchronous with respect to the corrugation recesses  31 , 192 . 
         [0214]    Referring to  FIGS. 21-22 , one embodiment of a flange  12  in accordance with the invention may effectively appear to have no core  190  when viewed from certain directions. For example, from “outside” the reel  10 , the outer surfaces  90   b,  corresponding to corrugations  30  having cavities  31  or recesses  31  of the flanges  12 ,  14  appear to extend from an arbor hole  32  out to the rim  16  or edge  16 . The rim  16  may actually be a strengthened portion of a flange  12 , or simply the outermost portion of an outer diameter of a single sheet of material. Thus, the corrugations  30  may extend from the arbor hole  32  radially outward to the edge  16  or a rim  16 . Any of the cross-sections discussed herein may be used. 
         [0215]    The sleeve  104  may be configured to extend axially from the flange  12  to be received within the tube  20 , or to receive the tube  20  therewithin. Thus, the tube  20  may abut the flange face  90   a  or surface  90   a  or may penetrate the face  90   a  to extend toward or beyond the outer face  90   b.  Thus, the sleeve  104  need not extend axially inward between the flanges  12 ,  14 , beyond an inner face  90   a.    
         [0216]    Referring to  FIGS. 23-24 , in one alternative embodiment of an apparatus in accordance with the invention, the core  22  need not be corrugated. That is, the core  22  need not be a corrugated core  190 . Rather, the core  22  may be perforated to provided apertures  226  positioned circumferentially to be radially opposite the recesses  31  of the corrugations  30 . In this embodiment, two tools such as drivers or wrenches, or a double-prong tool, such as a stapler, riveter, or the like, will be able to access space both inside and outside a tube  20 , in order to fasten the tube  20  securely with respect to the flange  12 . 
         [0217]    In certain embodiments, a manufacturer may rely on one or more sleeves  104 . Sleeves provide relief for hoop stress. Hoop stresses arise due to loads inside or outside of a continuous sleeve  104 . However, due to the improved fastening methods and the increased number and types of fastening methods available in producing an apparatus in accordance with the invention, sleeves  104  are not required. Instead, discontinuous tabs  228  can be affirmatively fastened to the tube  20 . 
         [0218]    The tabs  228  may extend from one flange  12  toward another flange  14 , or may extend from a flange  12  away from a flange  14 . Fasteners capable of carrying a tensile load along their principal axes can now be used. The tabs  228  may be bound to the tube  20  with radially oriented tensile forces in a fastener  212 . Thus, in addition to holding a shearing load acting in an axial direction  46 , the fastener may now also support a tensile load within an axis (acting radially with respect to the flange  12 ) of the fastener  212  itself. 
         [0219]    Noteworthy features of the discontinuous tab  228  design include the lack of hoop stress support, which was provided by the sleeve  104 . All hoop stresses imposed, whether compressive or tensile, in the tube  20  are supported only by the tube  20 . With appropriate tolerances, the tabs  228  may resist compressive forces inducing hoop stress on the tube  20 . However, since the tabs  228  are highly compliant in bending by comparison with a closed tube  20 , which must act according to hoop stress theory, the tabs  228  primarily orient the tube  20  and secure it against axial  46  loads and are not primarily responsible for handling hoop stresses. No transfer of loads between tabs  228  is possible, without some intervening element such as a corrugation wall  198 , or the tube  20  itself. 
         [0220]    Thus, provided with apertures  226 , the core  22  may provide access for a double-prong tool for fastening, even if corrugations are not required for structural reasons, The provision of tabs  228  provides locations suitable for applying penetrating fasteners or other fasteners (glue, welding, bonding, etc.). 
         [0221]    Referring to  FIG. 25 , a stapler  232  may be configured to have one or more prongs  234 ,  236 . In the illustrated embodiment the active prong  234  comprises a head  234  or other apparatus for dispensing a fastener  212 . Meanwhile, an opposing prong  236  provides an anvil  236  for receiving the fastener  212  and folding the fastener over. Accordingly, an aperture  30 , or the synchronous corrugations  30 ,  191  of an alignment region  210 , in the core  22  provides access for the anvil prong  236 . Otherwise, the single prong  234  or head  234  of the stapler  232  renders the stapler  232  a mere tacker. 
         [0222]    Other fastening devises may be similarly operable. For example, the two prongs  234 ,  236  in other tools may represent a screwdriver and a wrench, or a wrench and another wrench. Various types of drivers having different head shapes may be suited to different types of fasteners. The prongs  234 ,  236  may be wrenches, screwdrivers, other types of shaped drivers, or the like, necessary to operate at both extrema of any particular choice of fastener  212 . 
         [0223]    Referring to  FIGS. 26-28 , a tube  20  may be fastened to a tab  228  by a fastener  212 . The fastener  212  may extend radially  44  through the tab  228  first, or through the tube  20  first. In certain embodiments, tabs  228   a,    228   b  may flank a tube  20 , and thus support both extrema of the fastener  212 . In other embodiments, the tube  20  may be radially  44  outboard of the tab  228   a,  or may be positioned in board radially  44  with respect to the tab  228   b.  If the tube  20  is inboard of the tab  228   b,  then the tab  228   b  may preferably extend from a flange  12 ,  14  away from the opposing flange  14 ,  12 , respectively. 
         [0224]    Referring to  FIGS. 29-30 , other options in corrugating flanges  12  may include corrugating in multiple dimensions. For example, in the embodiment of  FIG. 29 , corrugations  30  have side walls  19  that are themselves undulating or otherwise varying in circumferential displacement along any radial path. The corrugation walls  19  may be configured in any suitable shape. Sinusoidal shapes, rectangular, angular, acute angular, obtuse angular, trapezoidal, and the like may be suitable configurations. Moreover, the wall  19  need not extend at right angles with respect to a surface  90 . The side walls  19  may be applied to any corrugation shape discussed herein. 
         [0225]    One of the benefits of the process of corrugating the sidewall  19  is the possibility of enhancing selective breakage and distortion in order to render the entire reel  10  more survivable. That is, catastrophic failure wherein the flange  12  separates from the tube  20  or wherein the flange  12  breaks, separating the core  22  from the outer region  200 , or wherein the tube  20  breaks, releasing its containment of the stranded material held thereon. Catastrophic failure is to be avoided. Distorted, damaged, chipped, partially fractured, and other conditions of flanges  12 , 14  may leave a flange highly serviceable, so long as the tube can exert radial force on the core  22 ,  190 , and so long as the outer portion  200  may exert axial restraint on the stranded material. 
         [0226]    In certain embodiments, ribs  244  may actually be corrugated in multiple dimensions. A flange  12  may effectively provide recesses  191  flanked in a circumferential direction by adjacent ribs  244 . The adjacent ribs  244  are corrugated in any suitable shape, whether sinusoidal, circular, curved, angular, and so forth as described with respect to the embodiment of  FIG. 29 . 
         [0227]    The embodiment of  FIG. 30  may necessarily provide less stiffness in certain orientations. Nevertheless, the flange  12  of  FIG. 30  may be modified in certain embodiments to render a base  240 , fastenable to a closure  242  thereof as a second piece for stiffening and bonding. Thus, the closure  242  may bond to the base  240 , boxing in the ribs  244 , and producing significantly more stiffness. Since maximum stress is located at the outermost fiber of any structure in bending, the base  240  and closure  242  provide members suitable for supporting the bending loads experienced by the flange  12 . 
         [0228]    A cavity  246  between the base  240  and the closure  242  renders the recess  191  a completely closed box. Contact regions  248  may include the core  22 , and specifically the cap portion  23 , bonded or otherwise secured to the closure  242 . Likewise, the edge  16  may provide a suitable contact region  248  for the base  240  and the closure  242 . The ribs  244  may be bonded to the closure  242 , or may be left free. One advantage of leaving the ribs  244  non-bonded to the closure  242 , may be to reduce stiffness that might otherwise provide catastrophic failure. The ability of the ribs  244  to move independently from the closure  242  may increase controlled, limited fracture to selectively absorb a certain amount of drop energy in order to effectively maintain the dimensions and serviceability of a flange  12 . 
         [0229]    Referring to  FIGS. 31-39 , the twin sheet concept may be considered as an optional alternative to the embodiment of  FIG. 30  and may be implemented in numerous configurations. In general, a base  240  may be formed in any suitable shape. A closure  242  may be formed in any complementary shape. 
         [0230]    The cavities  246  resulting from the fastening, securing, bonding, or otherwise positioning the base  240  and closure  242  together, may be completely empty, or may be provided a rib  244  parallel to the plane of cross-section illustrated. Such a rib  244  may be angled at any suitable angle, but may preferably be designed to completely fill the cavity  246 , extending to the closure  242 . In this way, additional stiffness may be selectively added as appropriate in any given design. 
         [0231]    In general, each base  240  may secure to a closure  242  over several suitable contact regions  248 . A fastener may extend through the base  240  and closure  242 , or a bonding method may be implemented. For example, glue, solvent, welding, contact pressure, melting, rivets, screws, bolts, staples, or other fastening means may be effective to secure the closure  242  structurally to the base  240 . 
         [0232]    Referring to  FIG. 31 , while continuing to refer generally to  FIGS. 31-39 , the wall  250  may be suitable for use in the corrugated core  190 , the outer region  200 , both, or for the entire region extending between an arbor aperture  32  and the edge  16 . In general, the cross-section illustrated may be regarded as either a circumferential or radial view (line of sight of a viewer), with differing results. That is, increased stiffness is typically expected when the cross-sections illustrated (see  FIGS. 31-39 ) is normal to a radius of the flange  12 . 
         [0233]    In certain embodiments, the wall  252  may be both rectangular in cross-section, and symmetric in construction. That is, the base  240  and the closure  242  may have matching, mirror-image structures providing contact regions  248 , and enclosed cavities  246 . 
         [0234]    Referring to  FIG. 33 , a non-symmetric wall  254  relies on a rectangular cross-section for the base  240 , is secured to the closure  242  in a contact region  248  to form a wall  254  of increased stiffness. The dimensions of the base  240  and closure  242  in each of the embodiments illustrated herein may be selected to provide the precise stiffness and strength desired. Accordingly, wall thicknesses, specific dimensions of corrugations, and the overall width of the wall  250 - 272  may be selected to optimize the use of materials, the overall weight, the structural strength, and the ability to selectively fail in a particular region of a flange  12  in order to preserve the overall integrity of a reel  10  containing a strand of material. 
         [0235]    Referring to  FIG. 34 , a wall  256  may be offset or counter-symmetric. That is, the wall  240  and the closure  242  may be identical. According to certain embodiments described herein, the base  240  and the closure  242  may have a certain right-handedness or left-handedness. Accordingly, even if not offset in a circumferential direction, the base  240  and closure  242  may not be mirror images of one another, rather, they may be identical, and have a right or left handed orientation, resulting in a counter-symmetric arrangement. 
         [0236]    In certain embodiments, the wall  256  may be viewed as having two parts  240 ,  242  which in the region of the outer portion  200 , or in the region of the core  190 , or in the region from the arbor aperture  32  out to the edge  16  of the flange  12 , may be mirror images of one another. Nevertheless, by rotating about an axis  50  of the flange  12 , the base  240  and closure  242  become somewhat offset from one another. Thus, certain flexibility and certain stiffness considerations may be balanced against one another as compared to a symmetric wall  252 , or non-symmetric wall  254 . 
         [0237]    Referring to  FIG. 35 , a wall  258  may be constructed to provide a base  240  having ribs  244  producing cavities  246 , which may or may not be filled with cross ribs  244  for extending substantially parallel to the cross-sectional plane of the wall  258  illustrated. In general, a closure  242  may have contact regions  248  associated with each rib  244 , and with other selected points of contact in the flange  12 . 
         [0238]    Referring to  FIG. 36 , in an alternative embodiment, a wall  260  may be provided with symmetric or counter symmetric construction. That is, the base  240  and the closure  242  may each be provided with ribs  244  and contact regions  248  between respective ribs  244  and the opposing part  242 ,  240 . Thus, the parts  240 ,  242  may actually be identical to one another or may be symmetric with respect to one another, or may be made in a suitable arrangement for interleaving, so to speak, the ribs  244  of the base  240  and the closure  242 . 
         [0239]    Referring to  FIG. 37 , in one alternative embodiment, a triangular cross-section in a wall  262  may include non-symmetric portions, a base  240  and a closure  242 . The contact region  248  may be large or small, and may include an elongation of contacting vertices in order to preclude overly sharp angles or limited sizes of contact regions  248 . In certain embodiments, two bases  240 , or a closure  242  similar to a base  240  may be configured to produce a diamond shape. Nevertheless, in most applications of reels  10 , the desire for a flat surface along an inside face  90  of a flange  12  militates in favor of a substantially flat surface  90 , or a surface that is sufficiently small in void fraction that stranded materials do not bulge into a recess  31  of a corrugation  30  in the outer region  200 . 
         [0240]    Referring to  FIG. 38 , a wall  264  provides a construction illustrating both a closure  242  that can be completely filled in, as well as a wall  240 , which may serve as a closure  242  having a very small void fraction. Thus, the uneven distribution of the cavities  246  on alternating sides of the base  240  minimizes the opportunity for a stranded material to bulge into the cavity  246 , while still providing substantial stiffness. 
         [0241]    Referring to  FIG. 39 , a comparison of alternative embodiments of reels  266 ,  268 ,  270 ,  272  or walls  266 ,  268 ,  270 ,  272  of reels  10  illustrates orientations that may be relied upon.  FIGS. 32-38  represent radial views of cross-sections (viewer looking along a radius of a reel  10 ), whereas the views of  FIG. 39  are circumferential views. Accordingly, spiral corrugations as described hereinabove, may be implemented according to the embodiments of  FIG. 39 . Furthermore, cross-sections at specific radii that do not vary may be alternative embodiments for which the cross-sections of  FIG. 39  are suitable. 
         [0242]    The wall  266  has a rectangular cross-section from a circumferential view. Similarly, the cavity  246  may include a rib  244  substantially parallel to the cross-section illustrated. However, such a rib  244  can help according to the extent of its particular filling or bracing across the cavity  246 , and may be angled at any suitable angle in any of three dimensions, in order to provide the right balance of manufacturability, stiffness, strength, and selective fracture or distortion in order to protect the integrity of the reel  10 . 
         [0243]    The wall  268  illustrates a trapezoidal construction with an optional rib  244 , which may be deleted in certain embodiments. In the embodiments shown, the tab  228  may be replaced with a recess  286  such that the tube  20  will penetrate the flange  12 , rather than vice versa. In this embodiment, the optional rib  244  provides additional stiffness since bending moments applied to the wall  268  may reveal weak spots in the contact regions  248 . 
         [0244]    In the wall  270 , the base  240  and the closure  242  are parallel. That is, the base  240  and closure  242  extend radially parallel to one another. Alternatively, in the wall  272 , the base  240  tapers as it extends in a radial direction  44  away from the axis  50  to minimize the space in the cavity  246  or the weight of the rib  244 , if the cavity  246  is filled with an optional rib  244  at periodic locations. One may note that the base  240  may be configured to occupy the space of the closure  242 , and a closure  242  may be constructed to occupy the place of the base  240 . Nevertheless, in general, a flat surface is desired for supporting the stranded material on a reel  10 . 
         [0245]    Some of the parameters available for varying the structural stiffness, strength, weight, and over all performance, as well as the resistance to distortion may rely on altering the geometries of the walls  266 - 272 . For example, a wall thickness  274  may be varied by selecting a size for corrugations  30 ,  192  and recesses  31 ,  192  that will maximize spacing distance, in order to maximize stiffness. Alternatively, a balance may be achieved, in which a wall thickness  274  and the thickness  276  of the base  240 , along with the thickness  278  of the closure  242  may be balanced against one another to provide a combination of weight, stiffness, and strength in tension, bending, compression, and buckling. 
         [0246]    Similarly, the inner radius  280 , outer radius  282  and flange radius  284  may be selected to balance the strength of the tabs  228  against the strength of the overall wall  250 - 272  in view of the strength of a tube  20 , and the fasteners  212 . Other parameters that may be considered are the size of fastened contact regions  248 . The degree or extent of bonding or fastening may be provided in order to allow the base  240  to separate selectively from part of the closure  242 , thus absorbing impact energy and preventing catastrophic failure. 
         [0247]    Various plastic molding techniques may produce flanges in accordance with the invention. These techniques may include blow molding, injection molding, vacuum forming, roto-molding, and fabrication from various shapes of stock including sheet stock, pressing, die stamping, and the like. Conventional molding techniques lack the regions of closed cross-section wherein a base layer  240  may be secured by a suitable method such as bonding to a closure layer  242  over an extensive contact region in order to make corrugated, closed cross-sections as contemplated for the invention. 
         [0248]    Individual layers  240 ,  242  may formed by any method individually, and later assembled. Alternatively, in selected processes, such as blow molding and roto-molding, care must be exercised in the spacing of the mold in the contact region. That is, in conventional molding, the distances required for the extensive lengths of a contact region may compromise structural integrity if left at conventional sizes. Accordingly, a mold may be fashioned having suitable dimensions to support the proper structural integrity over extended lengths and widths of contact regions  248  during molding. These distances may typically not be distances used conventionally for the molding techniques identified. 
         [0249]    From the above discussion, it will be appreciated that the present invention provides a method and apparatus for balancing strength, stiffness, fracture, and toughness in reels and spools, incorporating material properties. Accordingly, corrugations may be adapted to several configurations and a design process calculated to protect stranded materials contained on a spool or reel. 
         [0250]    Cost of material, molding speeds, and the like may all be affected as desired by selection of specific design criteria in accordance with the invention. Spools and reels from small unitary sizes on the order of inches or smaller may be produced according to the invention. Likewise, reels of substantial size for supporting large amounts of heavy materials such as wire, cable, wire rope, and the like may be designed in sizes having an order of magnitude on the order of feet. 
         [0251]    The present invention may be embodied in other specific forms without departing from its basic structures, methods, or other essential characteristics as broadly described herein and claimed hereinafter. The described embodiments are to be considered in all respects only as illustrative, and not restrictive. The scope of the invention is, therefore, indicated by the appended claims, rather than by the foregoing description. All changes coming within the meaning and range of equivalency of the claims are to be embraced within their scope.