Abstract:
A high strength low density multi-purpose panel. The preferred panel is made of a plurality of boxes, organized into rows and columns, and each preferably including four alternately inverted voids. The voids are preferably triangular in cross-section and rounded at their apex and corners. The box sides are preferably four solid panels. Cross panels, extending between opposite corners and between the faces of each box, intersect at each box center, resulting in an X-shaped cross in each box. Each box is rotated ninety degrees with respect to each adjacent box. Each box shares sides with four adjacent boxes and corners with four cater-corned boxes. The common sides create perpendicular sets of parallel braces running the panel&#39;s length and width. The shared corners align and join the X-shaped cross panels with the X-shaped cross panels of their cater-cornered neighbors, creating diagonal braces that run across the entire panel.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The invention relates to structural panels in general and to high strength low density panels in particular.  
         [0003]     2. Prior Art  
         [0004]     Construction panels that include void spaces in order to save on material and/or weight are well known in the prior art. However, many of these panels are deficient in at least one of several areas. The void spaces in many prior art panels are poorly designed. The internal shape of the void spaces are seldom configured to enhance the strength of the structure. Furthermore, the positioning of most prior art void spaces within the panel are not selected to facilitate reinforcement of the other void spaces. To the extent that the prior art panels have reinforcing members at all, the reinforcing members seldom extend across the entire panels in every direction. Thus, loads applied to an area of the prior art panels often must be borne by that area in isolation rather than distributing the load across the entire panel. Because of these design deficiencies, greater amounts of material are typically required to achieve the desired panel strength in the prior art. As a result, the prior art panels frequently either are not as economical as possible in terms of cost and weight or their desired strength is sacrificed to achieve weight and/or economic goals. Accordingly, a multipurpose panel meeting the following objectives is desired.  
       OBJECTS OF THE INVENTION  
       [0005]     It is an object of the invention to provide a construction panel that is relatively high in strength.  
         [0006]     It is another object of the invention to provide a construction panel that is relatively low in density.  
         [0007]     It is another object of the invention to provide a construction panel that is relatively economical in terms of material used.  
         [0008]     It is still another object of the invention to provide a construction panel having reinforcing braces extending the length and width of the panel.  
         [0009]     It is yet another object of the invention to provide a construction panel having reinforcing braces extending diagonally across the panel.  
         [0010]     It is still another object of the invention to provide a construction panel having reinforcing members extending the depth of the panel.  
         [0011]     It is yet another object of the invention to provide a construction panel whose void spaces are arched to maximize their weight bearing ability.  
       SUMMARY OF THE INVENTION  
       [0012]     The invention comprises a high strength low density panel. The panel comprises a plurality of boxes each of which preferably include four void spaces. The void spaces are rounded at their apex and three sided. The corners of the void spaces are preferably rounded. The void spaces are preferably alternately inverted with respect to each other in a radial fashion: up-down-up-down. The perimeter of each box is preferably made of four solid side panels, extending from the upper face to the lower face all the way around each box. Cross panels also extend from each corner of each box to the opposite corner. Like the side panels, the cross panels also extend from the upper to the lower face of each box. The cross panels meet and intersect at the center of each box, resulting in a generally X-shaped cross running from corner to corner in each box. A solid triangular panel is preferably positioned on the upper and lower face of each box, above each apex of each void space. The triangular panels meet in the middle of each face to create a generally hourglass shape. However, the triangular panels in the upper and lower faces are preferably rotated approximately ninety degrees with respect to each other.  
         [0013]     The boxes are organized in rows and columns. Each box is rotated approximately ninety degrees with respect to each adjacent box in its column and its row. This will result in each box sharing one side with each of the four adjacent boxes and sharing a corner with each of the four cater-corned boxes. By sharing sides with the row and column adjacent boxes, the common sides will create perpendicular sets of parallel braces that run across the length and width of the panel, repeatedly intersecting with one another. By sharing a corner with the adjacent cater-cornered boxes, the X-shaped cross panels of each box will align and join with the X-shaped cross panels of their cater-cornered neighbors, resulting in a set of diagonal braces that runs across the entire panel and which intersects and reinforces the other braces at the corner of each box, to provide a construction panel that is high in strength but low in density and weight. 
     
    
     BRIEF DESCRIPTION OF THE FIGURES  
       [0014]      FIG. 1  is perspective view of a preferred embodiment of a high strength low density panel according to the present invention  
         [0015]      FIG. 1A  is a perspective cut-away view of the preferred embodiment of the high strength low density panel of  FIG. 1  cut along line  1 A and with the preferred position of some of the braces illustrated in dashed lines.  
         [0016]      FIG. 2  is a perspective view of one half of a mold for forming a preferred embodiment of the high strength low density panel according to the present invention.  
         [0017]      FIG. 3A  is a cut-away side view of an open mold for forming a preferred embodiment of the high strength low density panel according to the present invention.  
         [0018]      FIG. 3B  is a cut-away side view of a closed mold for forming a preferred embodiment of the high strength low density panel according to the present invention.  
         [0019]      FIG. 4  is a top plan view of a preferred embodiment of a high strength low density panel according to the present invention with the preferred position of some of the bracing shown in dashed lines.  
         [0020]      FIG. 5  is a plan mirror image of the bottom of the high strength low density panel shown in  FIG. 4 .  
         [0021]      FIG. 6  is a perspective view of a box component of a preferred embodiment of a high strength low density panel according to the present invention.  
         [0022]      FIG. 6A  is a perspective view of the box component of  FIG. 6  rotated ninety degrees such that upper surface  11  is turned away from the viewer.  
         [0023]      FIG. 6B  is a top plan view of a box component of a preferred embodiment of a high strength low density panel according to the present invention.  
         [0024]      FIG. 6C  is a perspective cut-away view of the box component of  FIG. 6B  cut along line  6 C.  
         [0025]      FIG. 6D  is a perspective cut-away view of the box component of  FIG. 6B  cut along line  6 D.  
         [0026]      FIG. 6E  is a perspective cut-away view of the box component of  FIG. 6B  cut along line  6 E.  
         [0027]      FIG. 7  is a side cut-away and partially exploded view of the preferred embodiment of the high strength low density panel shown in  FIG. 1 , cut along line  7  and having laminated faces and flame retardant sound proofing material in its void spaces.  
         [0028]      FIG. 8  is a perspective view of a preferred embodiment of a high strength low density panel wherein the panel is curved. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0029]     The invention comprises a high strength low density structural panel  1 . Panel  1  may be flat or curved as desired. In the preferred embodiment, panel  1  is formed from a mold  2 . Mold  2  comprises a first plate  3  and a second plate  4 . A plurality of inserts  5  will be positioned on plates  3 ,  4 . Inserts  5  will preferably have a three sided conical or pyramidal shape, such that they will be generally triangular in cross section. Each side of inserts  5 , except the base, will preferably angle in toward one another. Each insert  5  will have three corners  7 . In the preferred embodiment, corners  7  will be rounded. The ends of inserts  5  distal from the plate  3  or  4  on which insert  5  is mounted will also be rounded.  
         [0030]     Inserts  5  will preferably be arranged on plates  3  and  4  in corresponding pairs and sets of pairs. Each pair of inserts  6  will comprise two inserts  5 . The inserts  5  of each pair  6  will preferably be positioned so that one of the corners  7  on one insert  5  faces one of the corners  7  on the other insert  5  in the pair. An opposing pair  8  of inserts  5  will be mounted on the opposite plate  3 ,  4  from the first insert pair  6 . The opposing pair  8  will be rotated approximately ninety degrees from the first pair  6 . When plates  3 ,  4  of mold  2  come together, the inserts  5  of each set of pairs  6 ,  8  will come together in an up-down-up-down radial pattern. The pairs  6 ,  8  will be organized on plates  3 ,  4  in rows and columns. Each pair  6 ,  8  will preferably be rotated about ninety degrees with respect to each adjacent pair  6 ,  8  in both the rows and the columns. As a result, each set of pairs  6 ,  8  will also be rotated approximately ninety degrees with respect to each adjacent set of pairs  6 ,  8 . The length and circumference of the inserts  5  may vary as desired.  
         [0031]     During the preferred manufacturing process, mold  2  will be closed, bringing plates  3 ,  4  together to the desired closeness. Mold  2  will then be filled with plastic, rubber, foam, cement, steel, aluminum, or any other moldable material. Once the material has hardened and/or cured, mold  2  will open leaving the desired high strength low density panel  1 .  
         [0032]     High strength low density panel  1  is comprised of a plurality of box shaped sections  10 . It will be appreciated by those skilled in the art that in the preferred embodiment boxes  10  will not be physically distinct from one another. Rather, each box  10  will preferably be joined seamlessly with its neighbors so that an integral panel  1  is provided. Thus, the side panels  16  (discussed below) of each box  10  will preferably be shared with adjacent boxes  10  as will corners  14  and corner edges  18  (also discussed below). However, for purposes of discussing panel  1 , it is convenient to consider the sections corresponding to each group of inserts  5  as boxes  10 .  
         [0033]     Each box section  10  has an upper face  11  and a lower face  12 . Upper face  11  and lower face  12  each have a midpoint  13 U and  13 L. Upper face  11  and lower face  12  are preferably generally rectangular and most preferably generally square in shape. Preferably, upper face  11  and lower face  12  will each have four corners  14  and be about the same size and shape.  
         [0034]     By positioning inserts  5  as described above in mold  2 , a continuous band of material  15  will extend from each corner  14  through midpoint  13 U or  13 L to the opposite corner  14 . These continuous bands of material  15  will thus extend generally diagonally across each face  11 ,  12  of each box section  10 , in a generally X-shaped pattern. Continuous bands of material  15  will strengthen each box  10 . Moreover, boxes  10  are positioned in panel  1  so that the corners  14  of one box  10  are adjacent to the corners  14  of three adjacent boxes  10 . At each corner intersection, each box  10  will share a side panel  16  with two radially adjacent boxes  10  but will touch the other adjacent, but non-radially adjacent, box  10  only at a corner  14 —i.e., the cater-corner box  10 . Continuous bands of material  15  in one box  10  will join with continuous bands of material  15  in the non-radially adjacent (cater-corner) box  10 . This will result in continuous bands of material  15  running diagonally across the upper and lower faces of the entire panel  1 , rather than simply across each individual box  10 . Thus, continuous bands of material  15  will provide reinforcement to the entire panel  1 .  
         [0035]     By making the external circumference of each set of insert pairs  6 ,  8  at least slightly smaller than the perimeter of each corresponding box  10 , a continuous column of material  17  will be provided at each corner edge  18 —that is that portion of each box  10  extending from one corner  14  of upper face  11  to the corresponding corner  14  of lower face  12 . The continuous columns  17  will provide compression strength to panel  1  in the dimension perpendicular to upper and lower faces  11 ,  12 . It will be understood that by “column” the inventor does not mean to imply that a smooth rod of material having a circular cross section will or must be found. To the contrary, the inventor means to encompass continuous sections of solid material of indeterminate and/or varying cross section in panel  1  where “columns” are recited.  
         [0036]     Another advantage that arises from making the external circumference of each set of insert pairs  6 , 8  at least slightly smaller than the perimeter of each corresponding box  10  is that a solid side panel  16 , extending from upper face  11  to lower face  12 , will be formed between each set of adjacent corner edges  18 . Solid side panels  16  will provide a solid perimeter  40  around each box  10 . Solid side panels  16  will incorporate continuous columns  17  and will provide compression strength to panel  1  in the same manner as columns  17 . Additionally, by arranging boxes  10  in panel  1  in rows  30  and columns  31  and by positioning boxes  10  so that each side panel  16  is shared with an adjacent box  10  (except at the edges of panel  1 ), the side panels  16  of each box  10  will align with and connect to the side panels  16  of the adjacent boxes  10  in each row and column. The result is a plurality of braces  21 A and  21 B running the length and width of panel  1 . Braces  21 A will be generally parallel to each other as will braces  21 B, but braces  21 A and  21 B will be generally perpendicular to one another and will interlock at the intersections.  
         [0037]     By positioning and sizing each set of insert pairs  6 ,  8  so that they do not touch at their inside surfaces facing one another, a central column of material  19  will be formed along the central axis  20  of each box  10 . These central columns  19  will strengthen panel  1  against compressive forces in the same manner as columns  17 .  
         [0038]     By positioning and sizing each set of insert pairs  6 ,  8  so that they do not touch at all, a pair of cross panels  22  will be formed in each box  10 . Cross panels  22  will extend from the interior surface of each corner edge  18  to the interior surface of the opposite corner edge  18  through and encompassing central column  19 , where cross panels  22  will intersect and interlock. Cross panels  22  will preferably extend from upper face  11  to lower face  12  of box  10 . Accordingly, cross panels  22  will further strengthen panel  1  against compressive forces in same manner as columns  19  and  17 . However, by arranging boxes  10  in panel  1  so that each box  10  is cater-corner to another box  10  (i.e., such that certain boxes  10  will share a corner edge  18  and only a corner edge  18 ), cross panels  22  of one box  10  may be aligned and joined with cross panels  22  of cater-corner boxes  10 , thereby forming a plurality of diagonal braces  23  extending across panel  1 . As with braces  21 A and  21 B, diagonal braces  23  will consist of two sub-sets of braces  23 A and  23 B, each generally parallel to the other members of the sub-set but generally perpendicular to the members of the other sub-set. Diagonal braces  23  and braces  21 A and  21 B will intersect with one another at the corner edges  18  of each box, thereby creating a continuously reinforced latticework throughout panel  1 . It will be noted that cross panels  22  are essentially vertical extensions of continuous bands  15 , described above.  
         [0039]     Each insert  5  will leave a corresponding void space  24  in boxes  10 . Each void space  24  will have a base  25  opposite an apex  26 , an interior  27 , and a longitudinal axis  28  extending from base  25  to apex  26  and positioned substantially parallel to central axis  20  of each box  10 . Inserts  5  will preferably be positioned and sized so that they do not extend the full depth of box  10 . Accordingly, in the preferred embodiment, apexes  26  of void spaces  24  will be contained within box  10  between upper face  11  and lower face  12 . Apexes  26  will preferably be concave with respect to interior  27 , and void spaces  24  will preferably taper from base  25  to apex  26 . This will provide an arched or domed effect to each void space  24 , which will help to distribute loads directed parallel to longitudinal axis  28 . Because inserts  5  are preferably triangular in cross-section, void spaces  24  will be triangular in cross-section as well. This will serve to inherently strengthen void spaces  24  and thus panel  1 .  
         [0040]     Although in the preferred embodiment, void spaces  24  have concave apexes and sides that angle inwardly, it would be possible to utilize inserts  5  that were essentially prism shaped, with straight walls and a flat end, to form void spaces  24 . This would result in a loss of strength in void spaces  24  as well as in the surrounding panel. However, the advantages gained from interconnecting diagonal braces  23  and braces  21 A and  21 B would still be present, as they are not dependent upon the shape of inserts  5  or void spaces  24 .  
         [0041]     By organizing inserts  5  into opposing pairs  6 ,  8 , void spaces  24  may be positioned so that their respective longitudinal axes  28  alternate in orientation—that is, so that void spaces  24  are inverted with respect to each radially adjacent void space  24  within each box  10 . This will help distribute compressive forces, perpendicular to upper and lower faces  11 ,  12 , throughout each box  10  as well as panel  1 . It will also create a solid section of material  29  in each upper face  11  and lower face  12  “over” each apex  26 , where “up” is in reference to (and away from) each base  25 . In upper face  11 , a solid section  29  will preferably extend from two adjacent corners  14  to about midpoint  13 U. A second solid section  29  will extend from the other two corners  14  of upper face  11  to about midpoint  13 U. Both solid sections  29  in upper face  11  will preferably be generally triangular in shape and will together cover about half of upper face  11 . Solid sections  29  will preferably meet at midpoint  13 U and will together have the shape of an hourglass. Solid sections  29  will preferably have substantially the same shape and configuration in lower face  12  except that solid sections  29  in lower face  12  will be rotated approximately ninety degrees about central axis  20  with respect to solid sections  29  in upper face  11 . It will be appreciated that in the preferred embodiment, solid sections  29  will generally be bounded on two sides by continuous bands  15  and that continuous bands  15  will be incorporated into solid sections  29 . Solid sections  29  will serve to brace and reinforce each box  10  as well as panel  1 .  
         [0042]     As noted above, sets of pairs  6 ,  8  will preferably be organized in mold  2  in rows and columns. As a result, boxes  10  will be organized in rows  30  and columns  31 , as well. By rotating each set of pairs  6 ,  8  of inserts  5  approximately ninety degrees with respect to each adjacent set of pairs  6 ,  8  of inserts  5 , each box  10  will also be rotated approximately ninety degrees about its central axis  20  with respect to each adjacent box  10  sharing a row  30  or a column  31  with original box  10 . Furthermore, it will also result in each adjacent box  10  not sharing a row  30  or a column  31  with original box  10  (i.e., each cater-corner box  10 ) being in rotational alignment with original box  10 . This will facilitate the connection of continuous bands  15  and cross panels  22  from one box  10  to another, and thus the reinforcement of the entire panel  1 .  
         [0043]     In one embodiment, each void space  24  is less than half the length of each central axis  20 . This will result in a central solid section of material, generally parallel to upper and lower faces  11 ,  12  extending through the middle of each box  10  and connecting to adjacent central solid sections of material in adjacent boxes  10  throughout panel  1 , further strengthening panel  1 .  
         [0044]     It will be appreciated that in the preferred embodiment, each box  10  is interconnected with each adjacent box  10 . Thus, when mold  2  is filled, all of the interstitial spaces between inserts  5  will be filled, and the resultant panel  1  will be one continuous piece.  
         [0045]     It will be further appreciated that, in general, the strength of panel  1  will vary in inverse relationship to the overall size of void spaces  24 . Thus, the strength of panel  1  may be generally increased by decreasing the size of inserts  5 . Although the drawings of the preferred embodiments of panel  1  illustrate void spaces  24  as being uniform in size and relative spacing, that does not have to be the case. If greater strength is desired in certain sections of panel  1 , inserts  5  may be diminished in size, moved closer together, or removed altogether in those sections.  
         [0046]     Panel  1  may be used to construct any structure where high strength and low density is important, either because of weight concerns or for reasons of economy. Examples include skis; surfboards; shelving; construction panels for buildings, aircraft, spacecraft, automobiles, boats, and etc. If desirable in the particular application, specific or general purpose fillers  50  may be added to some or all of void spaces  24  in panel  1 . Examples of filler material include sound dampening material such as polyether urethane or fire retardant materials such as asbestos, phenolic based foams, and gypsum sand. A laminated surface  51  may be applied over the upper and/or lower face of panel  1  for aesthetic, aerodynamic, hydrodynamic, or other reasons, as desired.  
         [0047]     Although the invention has been described in terms of its preferred embodiment, other embodiments will be apparent to those of skill in the art from a review of the foregoing. Those embodiments as well as the preferred embodiments are intended to be encompassed by the scope and spirit of the following claims.