Abstract:
A shipping pallet compatible with fork-lifts and pallet-trucks is made from stamped or die cut flat corrugated board. Stringer and cross-braces from an interlocking grid work to which a top and bottom flat sheet are attached by an adhesive. The pallet may be recycled as paper and not returned to the sender. Additional reinforcement structures may be added for heavier loads.

Description:
FIELD OF THE INVENTION 
   This invention relates to high strength recyclable corrugated pallets. 
   BACKGROUND AND PRIOR ART 
   Corrugated paper dates to the mid-19 th  century and corrugated paper for shipping pallets dates to the early 1970&#39;s in Japan. Most are based upon multiplying folded corrugated sheets to approximate the wooden stringers of conventional pallets. Wozniacki, U.S. Pat. No. 5,184,558 and Hutchison, U.S. Pat. No. 5,568,774 are representative. Such construction is suitable for most pallets used for shipping consumer items but is difficult to assemble without expensive automation and also difficult to ship in knock-down form. 
   Corrugated pallets have many advantages. Unlike wooden, plastic, or metal pallets, corrugated can be recycled at the recipient&#39;s location as paper/card board and does not have to be returned for reuse. Even so called “pallet pools” ship a lot of air. 
   Exported pallets pose two problems. Return is nearly impossible and the International Plant Protection Convention, as well as local laws in the EU, China and Australia effectively implement a ban on wood pallets which have not been certified to be fumigated by heat or pressure treatment with chemicals. Corrugated pallets, because of their processing, do not require fumigation and offer clear cost advantages in foreign shipping. 
   There exists a need for simple corrugated pallet designs which are strong but do not require expensive multiple-step die cutting and folding steps, do not require excessive adhesive to assemble and which can be assembled at the user&#39;s site by minimally skilled laborers. 
   BRIEF DESCRIPTION OF THE INVENTION 
   It is a first object of this invention to provide a rigid corrugated pallet for shipping and handling materials. 
   It is a second object of this invention to provide a corrugated pallet which can be shipped to the user in knock-down form. It is a third object of the invention to provide components for a corrugated container which require a minimal investment by manufacturers. 
   It is a fourth object of this invention to provide a corrugated pallet which is compatible with both fork lifts and pallet trucks. A fifth object of this invention is a corrugated pallet which is reinforced to allow stack heights equivalent to that obtained with wood and plastic pallets conventionally in use. 
   These and other objects may be obtained by forming a corrugated pallet using a single die cut sheet of corrugated for each stringer; a single die cut corrugated sheet for cross-bracing; and two flat corrugated sheets for the top and bottom faces. Additional sheets may be added to interdigitate with the basic stringers and cross-braces to increase load bearing capacity for heavier cases and higher stackings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  shows a stamped flat cross-brace for a corrugated pallet. 
       FIG. 2  shows a stamped flat stringer for a corrugated pallet. 
       FIG. 3  is an exploded view showing how the stringers and cross-braces interlock. 
       FIG. 4  is a partial cut-away of a completed corrugated pallet. 
       FIG. 5  is a stamped base support for a pallet with cut-outs for the wheels of a pallet truck. 
       FIG. 6  is a stamped reinforcement sheet for use in combination with a stringer and cross-brace grid. 
       FIG. 7A  is an exploded view of a pallet according to a second embodiment of the invention. 
       FIG. 7B  is a partially assembled pallet according to the second embodiment. 
       FIG. 7C  is a completed support system for a second embodiment of the invention. 
       FIG. 8  shows a cross-brace for the support system for a second embodiment according to  FIG. 7C . 
       FIG. 9  shows a stringer for the second embodiment. 
       FIG. 10A  shows a blank for a central brace for the second embodiment. 
       FIG. 10B  shows the blank of  FIG. 10A  after a first fold sequence. 
       FIG. 10C  shows the final fold to form the brace for the second embodiment. 
       FIG. 11A  is an exploded view of a central brace. 
       FIG. 11B  illustrates the assembled brace. 
       FIGS. 12A and 12B  are details of the fitment of the stringer and central brace. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   An easily assembled, light weight recyclable corrugated pallet can be assembled from three stampings. The size of each stamping would change with the size of the pallet, typically in full, half and quarter-pallet sizes, based on a common 40″×48″ standard (nominally 1.0×1.2m). In most circumstances, industry standard single wall (double face) corrugated board may be used although double wall and tri-wall board is readily available and suitable for heavier use. It is critical that the board be cut so that the flutes in the walls are arranged in the upright or vertical orientation in both the stringers and cross-braces when viewed in the plan-view of the deck. 
   The type and amount of adhesive and the paper quality of the cardboard depend upon intended use. Maritime transport calls for wet strength paper and water-resistant glue. Glue guns are most convenient for applying adhesive but brushes and rollers are suitable. 
     FIG. 1  shows the standard pattern for a cross-brace  1 . The blank  3 , the length of which conforms to the short side of the pallet face, is stamped to provide cut-outs  5  to receive the walls of the stringers. Between the cut-outs, the width of the blank is reduced at  7  to avoid interference with the stringer. 
   Cut outs  9  are cut from the width of the blank to fold lines  11 . When the blank is folded along the fold lines, the distance  13  between the fold lines  11  becomes the width of the cross-brace. 
   The flute direction is indicated by arrow  15 . The cut outs  9 , where the blank is folded along the fold line, form the cut out for the tines of a fork lift or pallet truck. 
   Stringer  21  is formed from a blank  23 , the length of which conforms to that of the long side of the finished pallet. Cut outs  25  are arranged to interdigitate with the cross-braces and the space  27  between cut outs  25  are relieved to mesh with the cross-braces. Fold lines  31  are formed so that the blank may be folded to form a rectangular stringer. The flute direction is indicated by arrow  35 . 
   When the cross-braces  2  and stringers  21  are folded along their respective fold lines and assembled as indicated in  FIG. 3 , a rectilinear gridwork is formed. Adhesive is then applied to the outer surfaces between the respective fold lines and flat corrugated panels applied to the adhesive. Preferably, adhesive is also applied to points of contact between cross-braces and stingers. 
   When the flat panels  29  and  31  have been adhered to the grid work, the result is that illustrated in  FIG. 4 . It is noted that the cut-outs  9 , aligned, provide openings for entry of tines of a fork lift or other fork-based warehouse handling systems. Additional cut-out  33  may be present to accommodate load wheels of a pallet truck. 
   The pallets may be printed with a bar code or an RFID may be used to assist in tracking in a plant, warehouse or loading dock. 
   For heavier loads or high stack heights, additional stampings may be incorporated into the basic structure.  FIG. 5 . illustrates a reinforcement section  51  formed from a blank  53  which has been cut-out to form three sections  54 ,  55  and  57 , separated by creases  61 ,  63 . When folded at the creases, the width of section  53 , together with the thickness of sections  55 ,  57 , fits the space between stringers. Cut-outs  65  align with the end cross-brace  1 , the cutouts  67  align with interior sections of cross-braces. An optional pair of open rectangular area  69  are available to receive the load wheels of a pallet truck. The ends  71  are cut to the full length of the pallet in section  54 , but shorter in sections  55 ,  57  to accommodate the stringers. 
   A second reinforcing section  81  is formed from a blank  83  and notched at the sides at  85  in the same pattern as in  FIG. 5 . The ends  87  are cut to be the full length of the pallet while accommodating the junction of stringer and cross-bracing. 
     FIG. 7A  is an exploded view of how the reinforcement pieces for  FIGS. 5 and 6  are assembled. Flat section  83  from  FIG. 6  is pressed into position parallel to the stringer below the top of the flutes of stringer  21  and below cross-brace  1 , with ends  87  projecting the full length of the stringers. The reinforcing pieces  51  are bent at creases  61 ,  63 . The sections  55 ,  57  become additional flutes which reinforce stringers  21  and cross-braces  1 , as shown in  FIG. 7B . 
   The assembled frameworks  89  is seen in  FIG. 7C . The space between section  54  and section  83  is sufficient for form openings  91  which will accept the tines of a forklift. A deck in the form of a flat panel  29  and a floor in the form of a flat panel  31  then are adhered to the top and bottom of the framework  89  to complete the pallet. Pallets of this construction have been shown to support over 6,000 pounds (2700 kg). 
   In another embodiment, a tubular reinforcing is employed. In this embodiment, a separate flat panel base or floor is not required. In this embodiment, tines of a forklift may enter the pallet on all four sides. 
     FIG. 8  shows the first element of this embodiment, a cross-brace  101 . The cross-brace is stamped from a blank  103 . Slots  105  and  106  are formed in section  102 , which ultimately becomes a flute. The length of the flute is limited at  107  to perfect interference with the stringer when assembled. Notched slots  108  assist in aligning tabs from the stringer, as will be described below. A deeper cut  109  provides space for passage of a tine. Crease line  111  is the fold line for forming flutes  102  and defines the width of the cross-brace as  113 . The flute direction is  115 . 
     FIG. 9  shows the stringer  121  according to this embodiment. The blank  123  is stamped to from slots  125  and  126  to form flutes  122 . The flute length is reduced at  127  to prevent interference with the cross-braces when assembled and notched slots  128  are made for ease of assembly in like manner as notches  108 . Deeper cuts are made at  129  to provide for passage of tines. Crease line  131  is the fold line for forming flutes  122  and defines the width of the stringer as  131 . The flute direction is  135 . 
   It is noted that the stampings produce two distinct sets of tabs on both cross-brace and stringer, broad tabs  117  and  137  and narrow tabs  119  and  139 . When assembled, it will be seen that these tabs insert into broad slots  105  and  125  and short slots  106  and  126 . 
     FIG. 10  shows the third component of this embodiment, a central brace  151  which becomes a rectangular brace between stringers when assembly is completed. A blank  153  is created at fold lines  155 ,  155 ′,  157  and  157 ′ to form a central base  159 , a pair of flute portions  161 ,  161 ′ and a pair of top sections  163 ,  163 ′. Holes are cut at  165  for the wheels of a pallet truck. Tine clearance is provided at  167 . Clearance for flutes  102  is provided by cuts at  169  and  171 . 
   The fourth component is flat panel  181  which forms the top surface of the pallet. 
   When the pallet is built the preferred method is to first assemble the cross-braces and stringers. A jig is used to hold one component, usually the stringers which have been folded along creases  131  to form flutes  122 . The cross-braces are folded along creases  111  to form flute  102  when pressed together, the tabs formed by cut  108  slides into slots  126  and the tab formed by slit  128  fits into slot  106 . For a full size pallet, three stringers and four cross-braces are used. 
   Next the central brace is folded along crease lines  155 ,  155 ′,  157  and  157 ′ to form a rectangular tube along the  121  direction and is pressed between the stringers. Slot  169  accepts the flange formed between slots  105  and  106  and the end of the cross-brace or the flange formed between slots  105  and  106  and the cut-out  109 . 
   After the cross-braces are assembled and prior to insertion of the central brace, it is preferred to spray surfaces of the cross-braces and stringers which will contact the central brace with a fast-drying adhesive. When assembled, as shown in  FIG. 11 , the central base  151  is flush with the exposed surface  123  of the stringers and the folded tops  163 ,  163 ′ abut in contact with the (reverse) face of stringer  103 . The top surface of cross-braces  101  and tops  163 ,  163 ′ is sprayed with adhesive and top surface  165  is applied. The detail of how the cross-braces stringers and central brace are fitted is shown in  FIGS. 12A and 12B . 
   The invention has been described in terms of preferred embodiments, which are exemplary but not limitative of the invention. Modifications apparent to a person of skill in the art are subsumed within the purview of the invention. 
   For recycling, the pallets may be crushed, shredded or otherwise modified for ease of shipment to a recycling plant. 
   INDUSTRIAL UTILITY 
   The corrugated pallets of this invention are easily shipped to a user in knock-down form for on-site assembly. The pallets are easily recycled and more economical than wood or plastic alternatives, especially for international commerce. 
   This invention has been described in terms of the preferred embodiment. Modifications and additions obvious to those skilled in the art are included within the sprit and scope of the invention.