Abstract:
Disclosed herein is a high strength container particularly suited for containing heavy materials and being stacked when fill and nested when emptied. The container includes a receptacle having tapered upright walls that are capped by a lid. The receptacle has an abruptly enlarged upper perimeter joined to a lower perimeter by a horizontal ledge, which resists bulging of the walls under heavy loading. The lid has grooves at stacking support surfaces in which reinforcing members are disposed. The reinforcing members can include winged saddles to disposed in indentations in the lid that are designed to better distribute loads through the receptacle.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims benefit to U.S. provisional application Ser. No. 60/185,803, filed Feb. 29, 2000. 
    
    
     STATEMENT CONCERNING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not applicable. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to molded plastic containers which are made to be stacked one on top of another. 
     2. Discussion of Prior Art 
     Bulk boxes or containers for shipment and storage may, when filled, weigh many hundreds, or even a few thousand, pounds. To conserve space in transit and storage, it is desirable that these containers be stacked one on top of another. Therefore, the load supported on the bottom container may be many thousands of pounds. 
     These containers are often molded of plastic materials and are made to be reusable. They must, therefore, be capable of supporting the weight without permanent deformation. It is also desirable that such boxes be nestable, so that when they are emptied they may be nested inside one another and returned for refilling. 
     SUMMARY OF THE INVENTION 
     The invention provides a bulk container, including a lid, which is capable of bearing high stacking loads when one container is stacked on top of the lid of the next lower container. 
     Specifically, the present invention provides a plastic container for carrying heavy loads having a receptacle and a lid. The receptacle is formed of upright walls joined together at a lower edge by a bottom so as to define an open cavity closable by the lid. The lid has a support surface on which the bottom of a second container stacked thereon is supported. An elongated reinforcing member is secured to the lid beneath the bottom of the second container so as to support the second container. The reinforcing member substantially spans the upright walls on opposite sides of the receptacle and is supported above the upright walls by a saddle which cradles the reinforcing member and distributes loading from the reinforcing member to the lid. 
     In a preferred embodiment, the receptacle bottom has three flat feet that project downwardly and the support surface of the lid defines three recessed surfaces sized to receive the feet of a second receptacle stacked thereon. The feet are spaced apart in parallel to define a pair of channels sized to receive forks from a forklift. Three reinforcing members are disposed in grooves extending substantially along the middle of the recessed surfaces so as to underlie said feet of receptacle stacked thereon. The saddles are recessed in portions of the lid. Each saddle has a generally U-shaped center portion, and wings extending laterally outwardly from upper ends of the center portion. Lower surfaces of the center portion and wings bear against surfaces of the lid. 
     One feature of the container that contributes to its high stacking-strength is that it includes the rigid reinforcing members disposed in the lid. Forces are transferred from the lid at the ends of the reinforcing members to the container walls below. The members extend long enough all the way across the width of the container so as to overlap the lower container&#39;s side walls at the ends of the members. Forces are transferred from the ends of the members to the lid by the saddles which extends below each member up along the sides of the member and out laterally from the sides of the member. 
     Another feature of the invention which contributes to the high stacking strength of the container is that the upper portion of the container is abruptly enlarged in relation to the lower portion. The abrupt enlargement creates a horizontal convolution which encircles the container for 360° and contributes to the ability of the sides of the container to resist bulging. It does this while permitting the use of generally vertically running convolutions in the side walls of the container, both in the lower portion and in the upper portion. However, the vertical convolutions in the upper portion are preferably offset from the convolutions in the lower portion to provide horizontal surfaces or cross sections that resist bulging and buckling of the side walls of the container. 
     Still another strength enhancing feature is that the corners of the container, where the top portion transitions to the smaller portion, are more gradually transitioned to the smaller portion than the sides of the container. This may be done with a sloping surface, or a generally conical section of a surface to join the enlarged top portion of the container to the relatively smaller bottom portion of the container at the corners of the container. Thus, the ability of the corners to withstand vertical loading is significantly increased to resist collapse of the corners. 
     These and other advantages of the invention will be apparent from the detailed description and drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a container and lid of the invention, the lid being illustrated without reinforcing members or saddles; 
     FIG. 2 is a perspective view of the container with the lid removed; 
     FIG. 3 is a side elevation view of the container; 
     FIG. 4 is an end elevation view of the container; 
     FIG. 5 is a top elevation view of the container; 
     FIG. 6 is a perspective view of the lid for the container, illustrated without reinforcing members or saddles; 
     FIG. 7 is a top plan view of the lid shown without reinforcing members or saddles; 
     FIG. 8 is a sectional view from the plane of the line  8 — 8  of FIG. 7, shown with a reinforcing member and saddle installed (one of three members and one of six saddles); 
     FIG. 9 is a sectional view from the plane of the line  9 — 9  of FIG. 7 showing the container, lid, reinforcing member and saddle assembly; 
     FIG. 10 is a sectional view from the plane of the line  10 — 10  of FIG. 7 showing the lid alone; 
     FIG. 11 is a sectional view from the plane of the line  11 — 11  of FIG. 7 showing the lid alone; 
     FIG. 12 is a sectional view from the plane of the line  12 — 12  of FIG. 7 showing the lid alone; 
     FIG. 13 is a sectional view from the plane of the line  13 — 13  of FIG. 7 showing the lid alone; and 
     FIG. 14 is a sectional view from the plane of the line  14 — 14  of FIG. 7 showing the lid alone. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIG. 1, a container  10  of the invention includes a receptacle  12  and a lid  14 . The container  10  also preferably is provided with three reinforcing members  18  (FIGS.  8  and  9 ), one provided in each of the grooves  20  provided in the lid  14 , and one saddle  22  received in the lid at each end of each of the members  18  with a total of six saddles per lid and three members per lid. The receptacle  12  and lid  14  are molded plastic, e.g. polypropylene, which may be made by a roto molding process, the members  18  are square steel tubes, and the saddles  22  are solid steel made from strap or bar stock. The dimensions of the receptacle  10 , are, for example, 45.25″×44.5″ at the top, and it is about 49″ tall. 
     Still referring to FIG. 1, the receptacle  12  has three feet  24 ,  26 ,  28  which run the width of the receptacle  12  at the bottom and define between them fork slots for the container  10  to be picked up by a forklift. The bottoms of the feet  24 ,  26 ,  28  are flat, as are the recessed surfaces  30 ,  32 ,  34  in the lid  14 . The surfaces  30 ,  32 ,  34  are recessed and large enough to receive the respective feet  24 ,  26 ,  28 . The grooves  20  are provided generally down the middle of the surfaces  30 ,  32 ,  34  and are approximately the height of the reinforcing members  18 , so that the top of the reinforcing members are flush with the surfaces  30 ,  32 ,  34 . As such, most of the weight exerted through the feet  24 ,  26 ,  28  is born by the reinforcing members  18 . 
     Referring also to FIGS. 2-5, the receptacle  12  tapers top to bottom, which is why the feet  24 ,  26 ,  28  can fit within the recessed surfaces  30 ,  32 ,  34 . This also permits one receptacle  12  to be nested inside of another with nesting stops provided by ledges  54 . The ledge  54  of the upper container has lower surfaces which abut the upper surfaces of the ledge  54  of the lower container when two receptacles  12  are nested together. Providing the nesting stops makes denesting containers easier. 
     One feature of the receptacle  12  which increases its ability to contain heavy loads of flowable materials, such as small items, is that the walls of the receptacle  12  are resistant to bulging. This includes the end walls  40 ,  42  and the side walls  44 ,  46 . What makes the walls  40 ,  42 ,  44 ,  46  resistant to bulging is that the upper portion  50  of the receptacle  12  is abruptly larger than the lower portion  52  at the ledge  54  which goes all the way around the receptacle  12 . The ledge  54  essentially provides a horizontal convolution which increases the resistance to bending in the horizontal direction of each of the walls  40 , 42 , 44 , and  46 . Vertical convolutions  57 , 59  are provided in the walls of the receptacle  12  as illustrated. The vertical convolutions  57  provided in the upper portion  50  are offset from the vertical convolutions  59  provided in the lower portion  52  since if they were not offset they would interrupt the ledge  54  to such an extent so as to create a weak point at which the wall could bend or bulge outwardly if loaded with a heavy, flowable load. 
     The upper portion  50  of the receptacle  12  has inwardly projecting ribs  65  that extend down to intersect the ledge  54 .(see FIG.  2 ). At the end walls  44  and  46  there are two taller ribs  65  spaced apart on opposite sides of a shorter rib  65  at the center of the walls. The other end walls  40  and  42  have two taller ribs  65  spaced apart along the width of the sides. These ribs  65  are structural vertical members of the upper portion  50  that are tied to the ledge  54 . This helps to transfer loads from the upper portion  50  through the ledge  54  to the walls of the lower portion  52 . 
     The size of the upper portion  50  changes abruptly from the size of the lower portion  52  at the ledge  54 , except at the corners  60  of the receptacle  12 . As illustrated, at each corner  60  there is a gradual transition provided from the lower portion  52  to the upper portion  50 . This transition is provided in the shape of a section of a cone, although any suitable shape could be provided which is capable of exerting a vertical load through the corner of the receptacle  12  without undue bending of the material at the corner. If an abrupt transition is provided at the corners of the receptacle  12 , the vertical load exerted on the corner when containers are stacked can cause the corners to bend or buckle. Thus, the gradual transition of the corners  60  provides substantial vertical loads to be transmitted from the upper portion  50  to the lower portion  52  through the corners. 
     The upper edge of each of the side walls  44 ,  46  is notched in three places at  64  so as to receive the grooves  20  in the notches  64 . The lid  14  has a peripheral lip  66  which runs all of the way around the lid  14  and receives within it the upper edge of the receptacle  12  for 360°, which also helps resist bulging of the side walls and end walls of the container  12 , especially at the top. 
     Referring particularly to FIGS.  1  and  7 - 14 , at the end of each groove  20 , an indentation  66  is formed which indentation is in the shape of the saddle  22 . The saddle  22  is trapped between the indentation  66  in the lid  14  and the reinforcing member  18 . The reinforcing member is secured to the lid  14  by any suitable means, such as one or more rivets, bolts, or other suitable means. As shown in FIG. 9, between the indentations  66 , the bottom of the groove  20  raises up so as to touch or be in close proximity to the bottom of the reinforcing members  18 . The top of the members  18 , as stated above, is flush with the surfaces  30 ,  32 ,  34  on which rest the feet  24 ,  26 ,  28  when two containers  10  are stacked on top of one another. As shown in FIG. 9, the members  18  are long enough to extend out to the upper edge of the side walls  44 , 46 , so that the load supported by the member  18  is transferred directly from the end of the member  18 , down through the saddle  22 , through the lower wall  70  of the depression  66  and to the top edge of the receptacle  12 , both in the center of the notch  64  and to the sides of the notch  64 , since the saddle  22  has wings  72 ,  76  which extend to the sides of each notch  64 . If desired, the saddle  22  may be formed so that weight from the end of the member  18  is first transferred to the wings  72  and  76  directly down through the side walls of the receptacle  12  to the sides of the notch  64 , before the bottom leg  78  of the saddle contacts or transfers any significant weight to the receptacle  12  in the middle of the notch  64 . This helps assure more equal loading along the length of the saddle  22 . 
     A preferred embodiment of the invention has been described in considerable detail. Many modifications and variations to the preferred embodiment will be apparent to those skilled in the art, which will be within the spirit and scope of the invention. Therefore, the invention should not be limited to the described embodiment. To ascertain the full scope of the invention, the following claims should be referenced.