Abstract:
A spool has a spirally-wound, elongated channel having a C-shaped cross-section with a pair of arms extending from a central web. The channel is oriented with the pair of arms parallel to the axis of the spool and with the central web extending radially, relative to the axis of the spool. The channel has a plurality of adjacent windings, a first and second of the arms of spirally-wound channel cumulatively forming the inner and outer surfaces of the spool. The arms are spaced apart a distance approximating the width of the central web, such that the central web of the windings of the channel is received between the arms of adjacent windings and is retained therein to establish an overlap of windings in the axial direction. Other embodiments feature S, B and E-shaped channels to form the spool, some embodiments having inner and outer layers of channel. The spool is suitable for holding wound, thin metal stock, such as aluminum for making beverage cans, having a smooth outer surface which preserves the smoothness of the wound stock.

Description:
FIELD 
       [0001]    The present invention relates to spools or “cores” around which thin stock materials, such as sheet metal, metal foil, wire, fabric or rope, may be wound to allow storage, transportation and/or handling of such stock materials, and more particularly, to such spools made from spirally wound material. 
       BACKGROUND 
       [0002]    Coiled products, such as aluminum sheet and foil, must be stored on and transported to customers using a central spool or core about which the product is wrapped. The dimensions and characteristics of such cores are generally specified by the customers, and must be compatible with the customers&#39; coil handling systems and minimize product damage during shipping and handling. For example, for high-volume, coiled aluminum sheet products, such as can stock, end stock and tab stock (all used in the manufacture of the aluminum beverage can), the cores used are typically thick walled tubes of laminated Kraft paper. Alternatives to paper cores, e.g., metal cores constructed by overlapping a corrugated strip into a spiral form around a mandrel are known. 
       SUMMARY 
       [0003]    The disclosed subject matter overcomes the disadvantages and shortcomings of the prior art by providing a spool having an axis, an axial length, an inner surface and a curved outer surface about which material may be wound. The spool has a spirally wound, elongated channel having a C-shaped cross-section with a pair of arms extending from a central web, the channel being oriented with the pair of arms having a component of extension parallel to the axial length of the spool and with the central web extending radially relative to the axis of the spool. The channel has a plurality of adjacent windings, a first of the arms of spirally wound channel cumulatively forming the outer surface and a second of the arms of spirally wound channel cumulatively forming the inner surface, the first arm and the second arm spaced apart a distance approximating the width of the central web, such that the central web of the windings of the channel is receivable between the arms of adjacent windings and is retainable therein to establish an overlap of windings of the channel in the axial direction. 
         [0004]    In accordance with an embodiment of the present disclosure, each of the first arm and the second arm has a first portion extending from the central web and a second portion extending from a free end of the arm to a transition portion extending between the first portion and the second portion, the second portion of the first arm and the second portion of the second arm having a first spacing there between approximating a second spacing between an exterior surface of the first portion of the first arm and an exterior surface of the first portion of the second arm. 
         [0005]    In accordance with another embodiment of the present disclosure, the channel exhibits a third spacing between an exterior surface of the second portion of the first arm and an exterior surface of the second portion of the second arm and the difference between the second spacing and the third spacing approximates a radial thickness of the second portion. 
         [0006]    In accordance with another embodiment of the present disclosure, the outer surface of the spool is cylindrical and smooth. 
         [0007]    In accordance with another embodiment of the present disclosure, at least one of the first arm and the second arm has an undulating form in cross-section, an interior surface of the undulating form engaging and mating with an exterior surface of an undulating form of an adjacent winding of the channel of the spool. 
         [0008]    In accordance with another embodiment of the present disclosure, both of the first arm and the second arm have an undulating form in cross-section. 
         [0009]    In accordance with another embodiment of the present disclosure, the undulating form has first and second bulges separated by a valley, the first bulge extending from the central web. 
         [0010]    In accordance with another embodiment of the present disclosure, the channel has at least one slot extending into the central web, the slot capable of receiving an end of at least one of the first arm and the second arm of an adjacent winding of the channel. 
         [0011]    In accordance with another embodiment of the present disclosure, the slot is blind and is angled at an acute interior angle relative to the central web. 
         [0012]    In accordance with another embodiment of the present disclosure, the channel has a pair of slots, a first slot disposed proximate a junction of the first arm with the central web and a second slot disposed proximate a junction of the second arm with the central web. 
         [0013]    In accordance with another embodiment of the present disclosure, the first arm and the second arm each have an angled portion proximate a free end thereof which inserts into a corresponding one of the first slot and the second slot of an adjacent winding of the channel. 
         [0014]    In accordance with another embodiment of the present disclosure, the channel has at least one groove in at least one of the first arm and the second arm disposed proximate the central web, and wherein at least one of the first arm and the second arm has an angled portion proximate a free end thereof which inserts into the groove of an adjacent winding of the channel. 
         [0015]    In accordance with another embodiment of the present disclosure, the at least one groove is disposed between the central web and the first arm. 
         [0016]    In accordance with another embodiment of the present disclosure, the at least one groove has a generally V-shaped cross-section. 
         [0017]    In accordance with another embodiment of the present disclosure, at least one of the first arm and the second arm has a plurality of openings formed therein and from which a tab depends at an angle relative thereto proximate at least one of the openings, at least one of the plurality of openings aligning with the tab of an adjacent winding of the channel, the tab inserting into the aligned opening and aiding in securing adjacent windings of the channel in relative juxtaposition. 
         [0018]    In accordance with another embodiment of the present disclosure, a spool has an axis, an axial length, an inner surface and a curved outer surface about which material may be wound and a spirally wound, elongated channel having an S-shaped cross-section with a pair of arms extending from a central web and having a component of extension in opposite directions. A first arm of the pair of arms has a first extension extending from an end of the first arm distal to the central web at an angle relative to the first arm and forming a top portion of the S-shape. A second arm of the pair of arms has a second extension extending from an end of the second arm distal to the central web at an angle relative to the second arm and forming a bottom portion of the S-shape, the second extension pointing towards a portion of the central web. A distal end of the second extension is distal to the second arm and is spaced from the central web by a first spacing, the channel being oriented with the pair of arms having a component of extension parallel to the axial length of the spool and with the central web extending radially relative to the axis of the spool. The channel has a plurality of adjacent windings, the first arm of adjacent windings of spirally wound channel cumulatively forming the outer surface and the second arm of adjacent windings of spirally wound channel cumulatively forming the inner surface, the first extension being receivable between the distal end of the second extension and the central web of an adjacent winding to interlock therewith and establish an overlap in the axial direction. 
         [0019]    In accordance with another embodiment of the present disclosure, the distal end of the second extension pushes the first extension of an adjacent winding of the channel toward the central web. 
         [0020]    In accordance with another embodiment of the present disclosure, a pushing arm extending from the distal end of the second extension, the pushing arm being captured in the interior angle formed between the first extension and the first arm. 
         [0021]    In accordance with another embodiment of the present disclosure, a spool having an axis, an axial length, an inner surface and a curved outer surface about which material may be wound has a spirally wound, elongated inner channel with a first central web and a first pair of arms spaced a first distance from one another. The inner channel is oriented with the first central web having a component of extension parallel to the axial length of the spool and with the first pair of arms extending therefrom at least partially in a radial direction away from the axis of the spool. The inner channel has a plurality of adjacent windings, the first central web of adjacent windings of spirally wound inner channel cumulatively forming the inner surface. A spirally wound, elongated outer channel has a second central web and a second pair of arms spaced a second distance from one another. The outer channel is oriented with the second central web generally parallel to the axial length of the spool and with the second pair of arms extending therefrom at least partially in a radial direction towards the axis of the spool. The outer channel has a plurality of adjacent windings, the second central web of adjacent windings of spirally wound outer channel cumulatively forming the outer surface. The outer channel is wound over the inner channel with one of the first pair of arms positioned between the second pair of arms, such that adjacent windings of spirally wound outer channel bridge adjacent windings of spirally wound inner channel limiting axial motion of the outer channel relative to the inner channel and limiting spacing between adjacent windings of the inner channel and spacing between adjacent windings of the outer channel. 
         [0022]    In accordance with another embodiment of the present disclosure, the first pair of arms converge towards one another at a distal end thereof and the second pair of arms converge towards one another at a distal end thereof, the first pair of arms with the first central web forming a triangular shape and the second pair of arms with the second central web forming a triangular shape. 
         [0023]    In accordance with another embodiment of the present disclosure, a first arm of a first adjacent winding of the outer channel and a second arm of a second adjacent winding of the outer channel are disposed within a first triangular shape of a first adjacent winding of the inner channel. 
         [0024]    In accordance with another embodiment of the present disclosure, a plurality of adjacent windings of the inner channel each capture the first arm and the second arm of adjacent windings of the outer channel within the triangular shape, thereby interlocking the inner channel and the outer channel. 
         [0025]    In accordance with another embodiment of the present disclosure, a plurality of adjacent windings of the outer channel each capture the first arm and the second arm of adjacent windings of the inner channel within the triangular shape, thereby interlocking the inner channel and the outer channel. 
         [0026]    In accordance with another embodiment of the present disclosure, the inner channel has a groove structure formed from a compound fold in the central web, the groove structure being disposed intermediate the first arm and the second arm, the groove structure of the inner channel defining an outwardly facing groove into which at least one of the first arm and the second arm of the outer channel is receivable. 
         [0027]    In accordance with another embodiment of the present disclosure, the outer channel has a groove structure formed from a compound fold in the central web, the groove structure being disposed intermediate the first arm and the second arm, the groove structure of the outer channel defining an inwardly facing groove into which at least one of the first arm and the second arm of the inner channel is receivable. 
         [0028]    In accordance with another embodiment of the present disclosure, the inner channel has a groove structure formed from a compound fold in the central web, the groove structure being disposed intermediate the first arm and the second arm. The groove structure of the inner channel defining an outwardly facing groove into which at least one of the first arm and the second arm of the outer channel is receivable. The outer channel having a groove structure formed from a compound fold in the central web, the groove structure being disposed intermediate the first arm and the second arm, the groove structure of the outer channel defining an inwardly facing groove into which at least one of the first arm and the second arm of the inner channel is receivable. 
         [0029]    In accordance with another embodiment of the present disclosure, the outwardly facing groove is dimensioned to receive the first arm and the second arm of adjacent windings of the outer channel and the inwardly facing groove is dimensioned to receive the first arm and the second arm of adjacent windings of the inner channel. 
         [0030]    In accordance with another embodiment of the present disclosure, at least one of the first arm and the second arm has a plurality of openings formed therein and from which a tab depends at an angle relative thereto proximate at least one of the openings, at least one of the plurality of openings aligning with the tab of an adjacent winding of the channel, the tab inserting into the aligned opening and aiding in securing adjacent windings of the channel in relative juxtaposition. 
         [0031]    In accordance with another embodiment of the present disclosure, a spool has an axis, an axial length, an inner surface and a curved outer surface about which material may be wound. 
         [0032]    A spirally wound, elongated inner channel has a first central web and a first pair of arms spaced a first distance from one another, the inner channel being oriented with the first central web parallel to the axial length of the spool and with the first pair of arms extending therefrom at least partially in a radial direction away from the axis of the spool. The inner channel has a plurality of adjacent windings, the first central web of adjacent windings of spirally wound inner channel cumulatively forming the inner surface. A spirally wound, elongated outer channel has a second central web and a second pair of arms spaced a second distance from one another, The outer channel is oriented with the second central web parallel to the axial length of the spool and with the second pair of arms extending therefrom at least partially in a radial direction towards the axis of the spool. The outer channel has a plurality of adjacent windings, the second central web of adjacent windings of spirally wound outer channel cumulatively forming the outer surface. At least one of the first arm and the second arm of at least one of the inner channel and the outer channel being scrolled inwardly toward the central web. 
         [0033]    In accordance with another embodiment of the present disclosure, both the first arm and the second arm of at least one of the inner channel and the outer channel are scrolled inwardly toward the central web imparting a B-shaped cross-sectional shape. 
         [0034]    In accordance with another embodiment of the present disclosure, both the first arm and the second arm of both the inner channel and the outer channel are scrolled inwardly toward the central web imparting a B-shaped cross-sectional shape, at least one of the inner channel and the outer channel having a spacing between the first arm and the second arm to accommodate at least one of the first arm and the second arm of the other of the inner channel and the outer channel therebetween. 
         [0035]    In accordance with another embodiment of the present disclosure, both the inner channel and the outer channel have a spacing between the first arm and the second arm to accommodate at least one of the first arm and the second arm of the other of the inner channel and the outer channel therebetween. The outer channel is wound over the inner channel with one of the first pair of arms positioned between the second pair of arms, such that adjacent windings of spirally wound outer channel bridge adjacent windings of spirally wound inner channel limiting axial motion of the outer channel relative to the inner channel and limiting spacing between adjacent windings of the inner channel and spacing between adjacent windings of the outer channel. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0036]    For a more complete understanding of the present invention, reference is made to the following detailed description of exemplary embodiments considered in conjunction with the accompanying drawings. 
           [0037]      FIG. 1  is a diagrammatic sequence showing the transition of a flat strip into a modified C-shaped channel through a sequence of bending steps in accordance with an embodiment of the present disclosure. 
           [0038]      FIG. 2  is a perspective, partially diagrammatic view of the fabrication of a spirally wound core in accordance with an embodiment of the present disclosure. 
           [0039]      FIG. 3  is a cross-sectional view of the spirally wound core of  FIG. 2  taken along section lines III-III and looking in the direction of the arrows. 
           [0040]      FIG. 4  is a cross-sectional view of a spirally wound core like that of  FIG. 3 , but utilizing a channel shape in accordance with another embodiment of the present disclosure. 
           [0041]      FIG. 5  is a cross-sectional view of a spirally wound core like that of  FIGS. 2 and 3 , but utilizing a channel shape in accordance with another embodiment of the present disclosure. 
           [0042]      FIG. 6  is a diagrammatic sequence showing the transition of a flat strip into a modified C-shaped channel through a sequence of bending steps and the winding of the resultant C-channel on a mandrel, in accordance with another embodiment of the present disclosure. 
           [0043]      FIG. 7  is partially diagrammatic view of two steps in the sequence of the fabrication of a spirally wound core using the modified C-channel of  FIG. 6  in accordance with an embodiment of the present disclosure. 
           [0044]      FIG. 8  is a diagrammatic sequence showing the transition of a flat strip into a modified C-shaped channel through a sequence of bending steps in accordance with an embodiment of the present disclosure. 
           [0045]      FIG. 9  is a perspective view of a modified C-channel in accordance with an embodiment of the present disclosure. 
           [0046]      FIG. 10  is a cross-sectional view of a spirally wound core like that of  FIGS. 2 and 3 , but utilizing a channel shape as shown in  FIG. 9 . 
           [0047]      FIG. 11  is a diagrammatic view of an apparatus for forming a spirally wound core from channel in accordance with an embodiment of the present disclosure. 
           [0048]      FIG. 12  is a cross-sectional view of internal windings of a spirally wound composite core in accordance with another exemplary embodiment of the present disclosure. 
           [0049]      FIG. 13  is a cross-sectional view of a spirally wound composite core of  FIG. 12 , but including exterior windings. 
           [0050]      FIG. 14  is a cross-sectional view of a spirally wound composite core in accordance with another exemplary embodiment of the present disclosure and positioned on a mandrel. 
           [0051]      FIG. 15  is a cross-sectional view of a spirally wound composite core showing interior and exterior windings in accordance with another exemplary embodiment of the present disclosure. 
           [0052]      FIG. 16  is a cross-sectional view of a spirally wound composite core showing interior and exterior windings in accordance with another exemplary embodiment of the present disclosure. 
           [0053]      FIG. 17  is a cross-sectional view of a spirally wound core made from modified channel in accordance with another exemplary embodiment of the present disclosure. 
           [0054]      FIG. 18  is a cross-sectional view of a spirally wound core made from modified channel in accordance with another exemplary embodiment of the present disclosure. 
           [0055]      FIG. 19  is a diagrammatic view of a structure for securing adjacent channels of a spirally wound core. 
       
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
       [0056]      FIG. 1  shows an end-on view of a strip  10 , e.g., made from a metal like aluminum, brass, copper or a polymer. In the case of a metal strip  10 , the strip  10  is bent continuously or in a sequence of steps into a modified strip or pre-form  12 , which, in cross-section (or as seen from an end-on view), has a recessed central web  14  from which extends a pair of straight extensions  16 ,  18 . 
         [0057]    The pre-form  12  is then bent (as shown by arrows A, B, C, D) into a modified C-shaped channel  20 , which in cross-section, has two arms  22 ,  24  co-extensively extending away from the central web  14  in the same direction, approximately perpendicular thereto. Opposing end portions  22   a ,  24   a  of the web  14  of the pre-form  12 , when bent, form portions of the arms proximate the central web  14 , which have a spacing S 1  between the outer surfaces of end portions  22   a ,  24   a , approximating the interior spacing S 2  between the arms  22 ,  24  proximate the opening of the C-shape. This bending to transition between the strip  10 , to the pre-form  12 , to the C-channel  20 , can be accomplished by passing the strip  10  through roller dies (not shown) or a pulling it through a lubricated stationary die (not shown) or by or other conventional metal forming methods. 
         [0058]    In the case of plastic, the C-channel  20  can be formed as a continuous extrusion from a melt or formed from a strip  10  that is deformable and settable, e.g., a thermoplastic via the application of bending and heating. 
         [0059]      FIG. 2  shows the formation of a spirally wound core  26 . More particularly, the C-shaped channel  20  is oriented with the arms  22 ,  24  approximately parallel to the outer cylindrical surface  28   s  of a mandrel  28  and is wound about the mandrel  28  or otherwise urged (e.g., by a set of roller dies configuring a virtual mandrel) into a spiral shape. As successive turns/windings  20   a ,  20   b , . . .  20   x  of the spirally wound C-shaped channel  20  are wrapped about the mandrel  28 , the open end of the C-shape defined by the spaced arms  22 ,  24  (with spacing  52 ) is pushed over the central web  14  and the portions  22   a ,  24   a  of the arms  22 ,  24  (with a spacing S 1  separating the outer surfaces thereof) of the C-channel  20  already wound on the mandrel  28 , such that succeeding windings, e.g.,  20   b  of the C-channel  20  overlap and grip previous windings, e.g.,  20   a , at the overlap, via friction, surface features or adhesive. 
         [0060]    A guide roller  30  urged by force E, e.g., exerted via a resilient member or hydraulic actuation, may optionally assist in pressing the succeeding windings  20   a ,  20   b  . . .  20   x  of the C-channel  20  into an overlapping relationship to form the core  26 . Alternatively, a guide surface tapering toward the core  26  and urging the C-channel  20  in the direction indicated by force E, may be used. A counteracting force F may be applied by a spring-loaded, rotatable, axially displaceable plate  311  (See  FIG. 11 ) to oppose the force E, to compress the adjacent turns  20   a ,  20   b  . . .  20   x  into overlapping engagement. Alternatively, the core  26  may be compressed by an assembly of rolls. As a further alternative, the C-channel  20  may be partially or completely pre-bent into an arc (to form the spirally wound cylindrically-shaped core  26 ) by bending rollers, such as  32   a ,  32   b ,  32   c . After a given length of core  26  has been built up from the winding of C-channel  20   a ,  20   b  . . .  20   x , a saw  34 , a cutting torch (not shown) or other cutting apparatus, is used to separate a portion of core  26  from the remainder present on the mandrel  28  allowing continuous winding of C-channel  20  and the cutting of successive segments of core  26  for a given application, e.g., for use as spools to wind sheet aluminum. 
         [0061]      FIG. 3  shows a portion of a wall  36  of the core  26  in cross-section, showing a plurality of side-by-side, overlapping C-channel windings  20   a ,  20   b  . . .  20   x  with the outer arms  24   a  . . .  24   x  forming an outer surface  38  of the wall  36  of the core  26  (See  FIG. 2 ) and the inner arms  22   a  . . .  22   x  forming an inner surface  40  of the wall  36  of the core  26 . Each of the C-channel windings  20   a  . . .  20   x  either overlap, are overlapped, or both, by an adjacent channel winding(s)  20   b  . . .  20   x −1. The extent of one overlap  42   x  (of channel winding  20   x  and  20   x −1) is depicted in dotted lines. The webs  14   a  . . .  14   x  provide a radially extending support, which resists radial forces exerted on the core  26 .  FIG. 3  illustrates that the outer surface  38  and the inner surface  40  are substantially continuous and flat, interrupted only by the joints between adjacent C-channel turns  20   a  . . .  20   x . The joints may be minimized by the geometry of the C-channel  20  (to provide a mating fit at the overlap  42 ) and by the degree that the overlapping C-channel windings  20   a  . . .  20   x  are pushed (compressed) into proximity. 
         [0062]      FIGS. 4 and 5  illustrate that the dimensions of the C-channel  20  may be varied to adjust the attributes of the resultant core  26 . More specifically,  FIG. 4  shows that the length of arms  22 ′ and  24 ′ may be reduced relative to arm portions  22   a ′ and  24   a ′ (e.g., in comparison to the relative sizing shown in  FIGS. 1 and 3 ), such that a given length of wall  36 ′ has more C-channel windings  20   a ′ . . .  20   x ′ and a greater number of webs  14 ′ providing support in a radial direction, given a similar overlap  42 ′. 
         [0063]      FIG. 5  shows that the overlap  42 ″ may be increased by enlarging the length of the arm portions  22   a ″ and  24   a ″ relative to the length of the arms  22 ″ and  24 ″, the overlap  42 ″representing a double thickness of C-channel  20 ″ in the area of the wall  36 ″ defined by the overlap  42 ″. 
         [0064]      FIG. 6  shows an end-on view of a strip  110 , e.g., made from materials and by methods similar to those described above with respect to the embodiment shown in  FIG. 1 . The strip  110  may be bent continuously, or in a sequence of steps, into a modified strip or pre-form  112 , which, in cross-section (or as seen from an end-on view), has a recessed central web  114  from which extends a pair of faceted extensions  116 ,  118 . The pre-form  112  is then bent into a modified C-shaped channel  120 , which, in cross-section, has two undulating arms  122 ,  124  co-extensively extending away from the central web  114  in the same general direction, approximately perpendicular thereto. The undulating arms  122 ,  124  of the C-channel  120  each have a pair of outwardly directed bulges  122   a ,  122   b  and  124   a ,  124   b , respectively. A first bulge  122   a ,  124   a , respectively, is near the central web  114  and a second bulge  122   b ,  124   b , respectively, is near the open end of the C-shape and separated from first bulge  112   a ,  124   a  by an inwardly directed bulge  122   c ,  124   c , respectively. 
         [0065]    The C-channel  120  is oriented with the arms  122 ,  124  generally parallel to the outer cylindrical surface of a mandrel  128  and is wound about the mandrel  128  or otherwise urged (e.g., by a set of roller dies configuring a virtual mandrel) into a spiral shape. As shown in  FIG. 7 , as successive turns of the spirally wound C-shaped channel  120  are wrapped about the mandrel  128 , the open end of the C-shape (defined by the spaced, undulating arms  122 ,  124 ) is pushed over the central web  114  of a portion of the C-channel  120  already on the mandrel  128 , in a manner similar to that described above relative to  FIG. 2 , such that succeeding windings of the C-channel  120  overlap.  FIG. 7  shows the overlapping of C-channel windings  120   a  and  120   b  to form a portion of a wall  136  of a core like wall  36  of core  26  of  FIG. 2 , but utilizing the C-channels  120  of  FIG. 6 . 
         [0066]    As shown in  FIG. 7 , the second bulges e.g.,  122   b ,  124   b  of each C-channel winding  120   a ,  120   b  . . .  120   x  has a shape similar to the first bulges e.g.,  122   a ,  124   a , but is dimensioned such that the open end of the C-shape of the C-channel windings  120   a ,  120   b  allows easy insertion of the central web  114  of an adjacent turn of the C-channel, e.g.,  120   a  therein, to build-up a spirally wound core, i.e., dimension S 1  is less than S 2 . 
         [0067]    As shown in  FIG. 7 , subsequent to the insertion/overlapping of adjacent turns of the C-channel  120   a ,  120   b  . . .  120   x , the second bulges  122   b ,  124   b  of each of the arms  122 ,  124 , respectively, of the C-channels  120   a  . . .  120   x  are urged towards each other by a set of roller dies  144 ,  146  or equivalent means to clamp the over-lapping second bulges  122   b ,  124   b  of a given C-channel, e.g.,  120   b , over the first bulges  122   a ,  124   a  of the adjacent C-channel turn, e.g.,  120   a , locking the adjacent turns  120   a ,  120   b  together to resist disassociation by forces exerted on the resultant winding core (like  26  of  FIG. 1 ) in a direction parallel to the axis of the core  26 . The over-lapping second bulges  122   b ,  124   b  are dimensioned and shaped such that when they are clamped over the first bulges  122   a ,  124   a , the mating surfaces thereof are complementarily shaped and substantially parallel. 
         [0068]      FIG. 8  shows an end-on view of a strip  210 , e.g., made from materials and by methods similar to those described above with respect to the embodiment shown in  FIGS. 1-7 . The strip  210  may be bent continuously or in a sequence of steps into a series of modified strips or pre-forms  212   a - 212   e  and finally, into a modified C-shaped channel  220 . The C-channel  220  has a central web  214  bounded by two angled slots  215 ,  217 , formed by walls  215   a ,  215   b ,  215   c  and  217   a ,  217   b  and  217   c , respectively. Two arms  222 ,  224  extend away from the slot walls  215   c  and  217   c , respectively, generally co-extensively and perpendicular to the web  214  and in the same general direction. The arms  222 ,  224  each have an inwardly directed lip  223  and  225 , respectively, at the open end of the C-shape, having an angle relative to a corresponding arm  222 ,  224  approximating that of the slots  215 ,  217 . 
         [0069]      FIG. 9  shows the C-channel  220  prior to bending. As in the above-described embodiments, the C-channel is oriented with the arms  222 ,  224  generally parallel to the outer cylindrical surface of a mandrel  28  and is wound about the mandrel  28  or otherwise urged (e.g., by a set of roller dies  32   a - 32   c  configuring a virtual mandrel) into a spiral shape. 
         [0070]      FIG. 10  shows that as successive turns of the spirally wound C-channel  220   a ,  220   b  . . .  220   x  are wrapped about the mandrel  228 , the inwardly directed lips, e.g.,  223   b ,  225   b  proximate the open end of the C-channel  220   b  are urged/guided into the angled slots  215   a ,  217   a  in the central web  214   a  portion of the C-channel  220   a  already on the mandrel  228  by temporary deformation, followed by relaxation of the deformation to allow a return to an un-deformed configuration via elastic memory. As elastic memory exerts itself, the lips, e.g.,  223   b ,  225   b  converge towards one another in the respective slots  215   a ,  217   a  and pull successive windings of the C-channel  220   a  . . .  220   x  toward one another in a self-induced elastic compression. The temporary deformation of the lips  223 ,  225  and arms  222 ,  224  may be done by roller guides or stationary tapered dies that guide a C-channel  220  into the deformed position at the time it encounters the mating slots. 
         [0071]    Optionally, the slots  215 ,  217  may be crimped down onto the inwardly directed lips  223 ,  225  by a die acting internally to the C-channel  220   b  as it is coupled to the prior winding of C-channel  220   a , i.e., by pressing against central web  214   a . Crimping may also be accomplished by a crimping roller pressing the windings  220   a  . . .  220   x  against the mandrel  228  to diminish the distance between walls  222 ,  224 , either independently, or in combination with crimping by an internal die. 
         [0072]      FIG. 11  shows an apparatus  300  for forming cores  326  from C-channel  20 ,  120 ,  220 . More particularly, a mandrel  328  is turned by a motor  301  or other drive means, pulling C-channel strand  320  onto the mandrel  328 . In order to start the continuous production of cores  326 , the strand must be clamped to the mandrel  328  until sufficient frictional interaction exists between the strand  320  and the mandrel  328  to draw and bend the strand over the mandrel  328 . As the strand of C-channel  320  is drawn onto the mandrel  328 , one or more rollers  330   a ,  330   b  push successive windings of C-channel into overlapping condition, as described above. The formative, continuous core  326   f  may be supported on the mandrel  328  and or rotated with the mandrel by rollers  303 ,  305  that may be driven or free turning. Brakes  307 ,  309  may be utilized to restrain the axial movement of the formative core  326   f  to allow compression of the C-channel windings and/or stop the rotation of the mandrel  328  to allow cutting of a core  326  from the formative core  326   f  by cutter  334 . Alternatively, a core restraint  311 , which is selectively rotatable and projectable/retractable in an axial direction, may be used to press against the formative core  326   f  to promote compression of the C-channel windings and/or to apply a braking force to stop the core  326   f  for cutting. As a further alternative, cores  326  may be cut from the formative core  326   f  as the formative core  326   f  is turned, e.g., by a cutting torch that is moved axially to compensate for the axially advancing formative core  326   f , in order to make a straight cut. 
         [0073]      FIGS. 12 and 13  show an alternative embodiment of the present disclosure having a core  426  with a wall  436  formed from interior windings  420   a  . . .  420   x  and exterior windings  431   a  . . .  431   x −1 of C-channel ( 420  and  431  generally, respectively) shown in cross-section and wound on a mandrel  428 , an outer surface  428 S of which is depicted by a dotted line. The C-channel  420  and  431  may optionally be identical, but oriented in opposite orientations when wound. The C-channel  420  is wound with the central web  414  thereof oriented generally parallel to the outer surface  428 S of the mandrel  428 . The arms  422 ,  424  of the C-channel  420  extend away from the mandrel  428  and are bent toward one another (as shown by the arrows on arms  422   x  and  424   x  of winding  420   x  in  FIG. 12 ) either before being wound on the mandrel or afterward, to form an open triangular shape in cross-section (see  420   a  . . .  420   x −1 in  FIG. 12 ). As shown in  FIG. 13 , outer windings  431   a  . . .  431   x −1 of C-channel  431  are wound about the interior windings  420   a  . . .  420   x  with the arms  433 ,  435  (See e.g.,  431   x −1) pointed toward the mandrel  428  and positioned between the open triangular shape of two adjacent interior windings  420 . Subsequent to the winding of the outer C-channel  431  onto the interior C-channel  420 , in the bridging configuration shown, the arms  433 ,  435  of the outer C-channel  431  and the arms  422 ,  424  of the inner C-channel  420  are bent to approximate a triangular shape (relative to respective webs  437 ,  414 ), interlocking the spirally wound C-channels  420 ,  431 . The webs  437   a  . . .  437   x −1 form the exterior wall surface  439  and the webs  414   a  . . .  414   x  form the interior wall surface  441  of the core  426 . The bending of the respective C-channels  420 ,  431  into a triangular cross-sectional shape may be facilitated by compressing the outer surface  439  toward the inner surface  441 . Displacements of the C-channels  420 ,  431  in a compressive direction are limited by the arms  422 ,  424 ,  433 ,  435  of the respective channels  420 ,  431  reaching a limit of travel at respective interior acute angles of the triangularly-shaped, mating C-channel. 
         [0074]      FIG. 14  shows an alternative embodiment of the present disclosure for making a core  526  on mandrel  528  with a wall  536  formed from interior windings  550   a  . . .  550   x −1 and exterior windings  550   a ′ . . .  550   x −1′ of E-channel ( 550  and  550 ′ generally, respectively, with exterior windings  550   a ′ . . .  550   x −1′ shown in phantom) wound on a mandrel  528 , having an outer surface  528 S. The E-channel  550  has a pair of arms  553 ,  555  extending from corresponding web portions  557 ,  559 . A central U-portion  561  defines a central cavity  563 . A pair of return U-portions  565 ,  567  connect the central U-portion  561  to the web portions  557 ,  559 , respectively. The E-channel  550  and  550 ′ may optionally be identical and have the same type of arms,  553 ,  555 , web portions  557 ,  559 , U-portion  561  and return U-portions  565 ,  567 , but oriented oppositely when wound to form the core  526 . While the E-channel  550 ,  550 ′ depicted in  FIG. 14  is symmetrical about the U-portion  561 , which is denominated a “central U-portion,” optionally, the U-portion  561  could be shifted off-center, such that web portions  557  and  559  would be of unequal length. 
         [0075]    The E-channel  550  is wound with the web portions  557 ,  559  thereof oriented generally parallel to the outer surface  5285  of the mandrel  528   a  and with the arms  553 ,  555  extending away from the mandrel  528 . Successive windings  550   a ,  550   b ,  550   x −1, etc. are wound in close proximity, one to another, such that the arms, e.g.,  553   b ,  555   a  of adjacent E channel windings  550   a  and  550   b  touch, or are closely spaced. Since the core  526  shown in  FIG. 14  is a spirally wound structure, the lower portion of the core  526  on the mandrel  528  has the same structures that are present on the opposite side of the core  526 , displaced axially. Once the inner windings  550   a  . . .  550   x −1 are wound onto the mandrel  528 , outer windings  550   a ′ . . .  550   x −1′ of E-channel  550 ′ are wound about the interior windings  550   a  . . .  550   x  with the arms  553 ′,  555 ′ pointed toward the mandrel  528  and positioned to be received in the central cavity  563  of central U-portions  561  of the inner windings of E-channel  550  already on the mandrel  528 . For example, arm  555   a ′ of winding  550   a ′ is received in central cavity  563   a  of E-channel  550   a . Simultaneously, arm  555   a  of winding  550   a  and arm  553   b  of winding  550   b  are received in central cavity  563   a ′ of outer winding  550   a ′. Central cavity  563   a ′ may optionally be dimensioned to squeeze arms  553   b  and  555   a  together and the U-portions  563   a ′,  565   a ′ and  567   a ′ may exhibit elasticity to enable deformation of U-portion  563   a ′ to accommodate arms  553   b  and  555   a , which are then urged together under the influence of elastic memory. This relationship between arms  553 ,  555  and U-portion  561  is exhibited along the width of the core  526 , alternatively, by the inner and outer windings of E-channel  550 ,  550   a , drawing the core  526  into axial compression. The webs  557 ′ and 559′ form the majority of the exterior wall surface  539  and the webs  557  and  559  form the interior wall surface  541  of the core  526 . In the case of both the outer wall surface  539  and the inner wall surface  541 , the central U-portions  561  and central U-portions  561 ′ form a minor portion of the respective surfaces. The overlaying/meshing of the respective E-channels  550 ,  550 ′ may be facilitated by compressing the outer surface  539  toward the inner surface  541 , e.g., with a press roller or tapered guide surface (not shown) or by exerting a tension on the E-channel  550 ′ as it is wound to make the core  526 . The length of the arms  553 ,  555  and web portions  557 ,  559  can be varied to provide a selected number of radial supports for a given length of core  526  and for controlling the wall  536  thickness, each mating junction of arms, e.g., 553, 555 with central U-portions  561 ′ and return U-portions  565 ′,  567 ′ providing six radial support members. 
         [0076]      FIG. 15  shows an alternative embodiment of the present disclosure wherein a core  626  has a wall  636  formed from inner and outer windings, e.g.,  670   a ,  670   a ′ of B-channel  670 . The B-channel  670  has a central web  672  bounded by end scrolls  674 ,  676 . The interior windings  670   a  . . .  670   d  of B-channel  670  are spirally wound on a mandrel  628 —like mandrel  528  of  FIG. 14 , with the web, e.g.,  672   a  facing the mandrel and the scrolls, e.g.,  674   a ,  676   a  pointing away from the mandrel  628 . One or more exterior windings  670   a ′ . . .  670   c ′ of exterior B channel  670  are wound over the interior B-channel  670  with the webs  672   a ′ . . .  672   c ′ thereof pointed away from the mandrel  628  and the scrolls, e.g.,  674   a ′ and  676   a ′ pointed toward the mandrel  628 . As shown, the scrolls  674   a ′ . . .  674   c ′ and  676   a ′ . . .  676   e  of the outer windings  670   a ′ . . .  670   c ′ insert between the scrolls  674   a  . . .  674   d  and  676   a  . . .  676   d  of the inner windings  670   a  . . .  670   d , each bridging the adjacent windings of the other and with the scrolls interleaved. For example, outer winding  670   a ′ bridges adjacent inner windings  670   a  and  670   b , with scroll  676   a ′ inserted between scrolls  674   a  and  676   a  interleaved with scroll  674   a . Scroll  674   a ′ is interleaved with scroll  676   b  of inner winding  670   b . The composite core  626  has an inner wall surface  641  formed by the webs  672   a  . . .  672   d  of the interior B-channel windings  670   a  . . .  670   d  and an exterior surface  639  formed by the webs  672   a ′ . . .  672   e  of the exterior windings  670   a ′ . . .  670   e  of the B-channel  670 . In this embodiment, as in other embodiments of the present disclosure, the exterior windings  670   a ′ . . .  670   c ′ of the B-channel  670  and/or the interior windings  670   a  . . .  670   d  of the B-channel  670  may be secured to one another by welding, riveting, adhesives or fasteners at one or more locations, e.g., at the ends, to prevent unwinding. 
         [0077]      FIG. 16  shows an alternative embodiment of the present disclosure similar in some ways to that of  FIG. 15 , in that the inner B-channels  770   a  . . .  770   c  are similarly dimensioned as the exterior B-channels  774   a  . . .  774   c , e.g., identical, but reversed in orientation during winding. The distance W 3  between the scrolls  777 ,  779  may optionally be approximately twice that of the width W 4  of the scrolls  777 ,  779 , such that the scrolls  777 ,  779  of adjacent interior B-channels  770  may be accommodated between the spacing of width W 3  between scrolls of an exterior B-channel and vice versa, without interleaving. The scrolls, e.g.,  777 ,  779  of the B-channel  774 , provide radial reinforcement of the core  726  when wound to form composite wall  736 , but also retain elasticity since the scrolls  777 ,  779  are not attached to web  775 , lending resistance to radial deformation of the core  726 , as well as a degree of elasticity permitting deformation and recovery after deforming forces are removed. 
         [0078]      FIG. 17  shows an alternative embodiment of the present disclosure having a core  826  with a wall  836  formed from a spirally wound, modified S-channel  827 . The core  826  is wound around a mandrel  828 , as in previously described embodiments. The S-channel, in cross-section, features a central web  814  from which extends top arm  822  and bottom arm  824 , the bottom arm  824  extending away from the central web  814  in a substantially opposite direction compared to the top arm  822 . An abutment arm  829  extends from an end of the top arm  822  distal to the central web  814 . A diagonal arm  833  extends at an acute angle from the end of the bottom arm  824  and directed back toward the central web  814 . A pushing arm  835  extends from the end of the diagonal arm  833  distal to the bottom arm  824 . The modified S-channel  827  is wound on the mandrel  828  with the top and bottom arms  822 ,  824  thereof oriented generally parallel to the outer surface  8285 . Subsequent windings, e.g.,  827   b  overlap prior windings, e.g.,  827   a  with the abutment arm  829   b  inserting between the junction of the diagonal arm  833   a  and pushing arm  835   a  and the web  814   a  of the previous winding  827   a  of modified S-channel. As the subsequent winding, e.g.,  827   b  is drawn down tightly onto the mandrel  828 , the pushing arm, e.g.,  835   a  of the prior winding of modified S-channel, e.g.,  827   a  is trapped in the corner formed between abutment arm  829   b  and top arm  822   b , such that the diagonal arm  833   a  pushes the winding  827   b  in an axial direction toward the prior winding  827   a . The top arms  822   a  . . .  822   c  and the bottom arms  824   a  . . .  824   c , respectively, form the exterior wall surface  839  and the interior wall surface  841  of the core  826 . Displacements of the core  826  in a radially compressive direction are limited by the central webs  814   a  . . .  814   c , as well as by the diagonal arms  833   a  . . .  833   c  and the pushing arms  835   a  . . .  835   c , the latter two elements having a degree of elasticity and elastic memory that may absorb energy and restore in response to compressive forces. 
         [0079]      FIG. 18  shows an alternative embodiment of the present disclosure wherein a wall  936  of the core  926  in cross-section, has a plurality of side-by-side, overlapping modified C-channel windings  920   a ,  920   b  . . .  920   x . The outer arms  924   a  . . .  924   x  form an outer surface  938  of the wall  936  of the core  926  and the inner arms  922   a  . . .  922   x  form an inner surface  940  of the wall  936  of the core  926 . Each of the C-channel windings  920   a  . . .  920   x  either overlap, are overlapped, or both, by an adjacent channel winding(s)  920   b  . . .  920   x  similar to the embodiment shown and described above in  FIGS. 1 and 3 . The outer arms  924   a  . . .  924   x  have an inwardly directed grip arm  925   a  . . .  925   x  that is received in a groove  927   a  . . .  927   x  on the adjacent winding, e.g., grip arm  925   b  is received in groove  927   a . The angle of the grip arm  925   x  relative to the outer arm  924   x  may be varied. As shown by winding  920   x , the C-channel may be wound onto the mandrel  928  and positioned against an adjacent winding  920   x −1 with the outer arm  924   x  displaced upwardly, out of parallel with the inner arm  922   x  to facilitate adjacent positioning. The outer arm  924   x  is then bent down, e.g., by a pressure roller or guide surface, such that the grip arm  925   x  enters the groove  927   x −1. Alternatively, rollers and guide surfaces can be omitted if the C-channel  920  is fed onto the mandrel  828  with the arms  922   a  . . .  922   x  distal to the mandrel and the arms  924   a  . . .  924   x  proximate the mandrel, such that the arms  924   a  . . .  924   x  are flattened down as winding takes place. As shown in  FIG. 18 , the spirally wound C-channel  920  defines a continuous spiral hollow  950  which extends through the core  926 . This type of hollow may be also be observed in the embodiments described above relative to  FIGS. 1-17 . 
         [0080]      FIG. 19  shows a channel  1020  in accordance with an alternative embodiment of the present disclosure and having at least one opening  1081  punched therein leaving a hanging tab  1083  attached at one edge  1082 . The tab  1083  may be formed in a portion  1024  of the channel  1020  that, when wound to form a spiral core, overlaps another portion  1024   a  of the adjacent channel  1020  winding. As shown in  FIG. 19  the other portion  1024   a  which is overlapped may also have an opening  1087  or openings formed therein, such that the tab  1083  of the overlapping portion  1024  extends into the opening  1087  made in the overlapped portion  1024   a , stabilizing relative motion in the direction S between the overlapping portion  1024  and the overlapped portion  1024   a . More particularly, the periphery of the opening  1087  in the overlapped portion  1024   a  will encounter the tab  1083  of the overlapping portion  1024  to limit the relative motion. This feature can be utilized in areas of overlap such as the overlap  42  shown in  FIG. 5 , where the upper arm  24 ″ and the reduced spacing portion  24   a ″ can be punched to create one or more tabs  1083 ,  1085  and openings  1081 ,  1087 , respectively, which can be aligned, such that the tab  1083  of the overlapping portion  24 ″ extends into the opening  1087  formed in the overlapped portion  24   a ″. In this application, the tab  1083  will aid in preventing adjacent windings of C-channel from disassociating. The openings  1081 ,  1087 /tabs  1083 ,  1085  may be formed prior to bending or winding the C-channel, during winding, or after winding. The aligned tabs  1083  and openings  1087  may also be utilized with other of the embodiments depicted and described herein. 
         [0081]    As described above and shown in the Figures, the term “C-channel” has been used and is intended to describe a variety of channels having a C or modified C shape. The C-shape of the above-described C-channels has a pair of arms extending from a web, with each arm having a direction of extension with a component of direction parallel to the other arm of the pair. The arms are, in this sense, “parallel.” One or both of the arms may have one or more facets or curves, such that they are not completely straight, but nevertheless can be observed to have an average or general direction. Alternatively, the arms may be straight. An aspect of the cores described above which are formed from a spirally wound C-channel with the arms extending in a direction having a component of extension in parallel with the axis of the resultant core is that the webs thereof extend outwardly from the axis of the resultant spool/core with a component of extension perpendicular to the axis. The term “radial” is therefore intended to encompass extension perpendicular to the axis or extension which has at least a component of direction perpendicular to the axis of the spool/core. Cores made from the disclosed C-channel e.g.,  20 ,  120 ,  220 ,  320 ,  420 ,  550 ,  671 ,  770 ,  827 ,  927  provide advantages in that the outer surface of the core (that which is in contact with the wound sheet or foil product) can be manufactured with a smooth face. This smoothness prevents the loss of inner windings of product that is wrapped on the core, e.g.,  26 ,  827 ,  326 . The webs, e.g.,  14 ,  114 ,  214  provide an “I-beam” structure, a radially oriented spiral web, making the core stronger and more rigid for a given weight. The interlocking C-channels, e.g.,  20 ,  120 ,  220 ,  320 ,  927  can be wound onto the mandrel  28  with a specified axial overlapping, such that the spacing of the radial webs  14 ,  114 ,  214  and the wall  36 ,  136 ,  236  bending stiffness are easily adjusted/set for a given application. Optionally, the axial overlap of C-channels, e.g.,  20 ,  120  could vary across the axial length of the core. This provides the option of making a portion of the core, e.g., the ends, stronger relative to the remainder, attributable to greater overlap. The cores, e.g.,  26 ,  326 ,  926  have a smooth inside diameter (ID), reducing the chance that the ID of the core will be damaged by handling equipment and facilitating interaction between the core  26 ,  326  and handling. 
         [0082]    Cores  26 ,  326  made from the disclosed C-channel  20 ,  120  provide a double walled thickness to the desired degree via a selective degree of overlap. Double wrapped or composite cores  426 ,  526 ,  626  and  726  provide a double thickness wall  436 ,  536 ,  636 ,  736  with a variety of intermediate structural features to enhance strength and rigidity. The cores  626 ,  726  and  826  have resilient members that impart a degree of resilience to deformation forces. The core, e.g.,  26 ,  326 ,  826  may be made from recyclable material and may be formed from the same composition as the sheet product being shipped. For example, an aluminum core  26 ,  326 ,  736  may be used to hold aluminum sheet. It is possible to construct cores  26 ,  326 ,  736  using sheet metal, which for various reasons, such as width, gauge, crystallographic texture, or staining, does not meet customer specifications and which would be scrapped. Use of scrap coils provides inexpensive and readily available feedstock material for the manufacture of the winding cores  26 ,  326 . An all-metal core  26 ,  326 ,  626 ,  826  e.g., an all-aluminum core, can be conveniently recycled if it is constructed of the same or similar alloy from which the sheet product is produced, e.g., unused portions of the coils of sheet product on the core  26 ,  326  can be recycled together with the core  26 ,  326 . 
         [0083]    It is understood that the embodiments described herein are merely exemplary and that a person skilled in the art may make many variations and modifications without departing from the spirit and scope of the claimed subject matter. All such variations and modifications are intended to be included within the scope of the appended claims.