Abstract:
Shelves in a collapsible shelving structure are foldable about respective fold lines extending widthwise of respective shelves to load-bearing states.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention generally relates to erectable shelving structures constituted of a corrugated board material. 
   2. Description of the Related Art 
   Shelving structures that are movable from a collapsed position to an erected position are know. For example, U.S. Pat. No. 5,315,936 discloses a shelving structure wherein the movement of vertical side panels causes individual shelves to deploy to a load-supporting, generally horizontal state. 
   As advantageous as some of these known shelving structures are, they still occupy a relatively large amount of space, because each shelf is not foldable about a fold line extending across its width. Such a fold line tends to weaken the shelf and detracts from its load-supporting function. Instead, as disclosed in the aforementioned patent, each shelf is not foldable widthwise, but instead is lowered into position by being pivoted along a rear edge extending lengthwise of the shelf. 
   SUMMARY OF THE INVENTION 
   Objects of the Invention 
   Accordingly, one object of this invention is to advance the state of the art of erectable shelving structures. 
   Another object of this invention is to provide an erectable shelving structure having a plurality of shelves which are simultaneously moved to respective load-bearing states in a simple, convenient manner. 
   Still another object of this invention is to reduce the amount of space occupied by a collapsed shelving structure. 
   Yet another object of this invention is to fold shelves widthwise without compromising the structural strength of the shelves to bear loads. 
   FEATURES OF THE INVENTION 
   In keeping with these objects and others which will be apparent hereinafter, one feature of this invention resides, briefly stated, in a shelving structure comprising a pair of side walls, and at least one foldable shelf having opposite end regions hinged to the side walls. The side walls are movable toward and away from each other along a longitudinal axis between a collapsed position and an erected position. During this movement, each shelf is unfolded along a fold line extending transversely of the longitudinal axis from a folded state to an unfolded, load-supporting state. The fold line is midway between the opposite end regions of a respective shelf, and is midway between the side walls. 
   In accordance with this invention, each shelf has an upper shelf wall and a lower shelf wall. The upper shelf wall has a non-linear slit extending therethrough, and upper projections extending in opposite directions along the longitudinal axis across and past the fold line. The fold line is provided on the lower shelf wall and, more particularly, on an outer liner glued to a middle fluted layer where, in the preferred embodiment, the shelves, as well as the side walls, are constituted of a corrugated board material. 
   The middle fluted layer also has a non-linear slit extending therethrough, and lower projections extending in opposite directions along the longitudinal axis across and past the fold line. The lower projections alternate with the upper projections along the fold line. The upper projections abut against the lower projections to hold each shelf in the load-bearing state in which the shelf extends in a plane along the longitudinal axis between the side walls in the erected position. 
   The provision of a fold line transversely of the shelf does not compromise the strength thereof, because of the locking engagement between the upper and lower projections. Thus, the structure in its collapsed position, in which the side walls overlie and sandwich the folded-up shelves therebetween, is compact and occupies relatively little space. 
   The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view of a shelving structure in a position midway between its collapsed and erected positions; 
       FIG. 2  is a perspective view of the structure of  FIG. 1  in the erected position; 
       FIG. 3  is an enlarged, sectional view taken on line  3 — 3  of  FIG. 2 ; 
       FIG. 4  is an enlarged, sectional view taken on line  4 — 4  of  FIG. 3 ; and 
       FIG. 5  is an enlarged, sectional view taken on line  5 — 5  of FIG.  3 . 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Referring now to the drawings, reference numeral  10  identifies a shelving structure which is shown in an erected position in FIG.  2  and in a partially collapsed position in FIG.  1 . Structure  10  includes a pair of side walls  12 ,  14  of corrugated board material. Each side wall is a double wall and includes outer walls  12   a ,  14   a  and inner walls  12   b ,  14   b . Structure  10  also includes a rear wall  16  of corrugated board material and having rear wall portions  16   a ,  16   b  foldable about a vertical upright axis  18 . 
   Structure  10  still further includes a plurality of shelves  20  arranged at different elevations along the upright axis  18 . Each shelf is made of corrugated board material and is foldable about a fold line  22 , as explained in detail below. Each shelf has a first shelf section  24  and a second shelf section  26  both foldable about the fold line  22 . First section  24  has a hinge flap  28  at its outer end region adhered to inner wall  14   b  (see  FIG. 3 ) and pivotable about linear edge  30 . Second section  26  has a hinge flap  32  inserted into a cutout  34  in the inner wall  12   b  (see  FIG. 3 ) and positioned in a space between the inner and outer walls  12   b ,  12   a . Second section  26  is pivotable about linear edge  36 . 
   Thus, as seen in  FIG. 2 , the side walls  12 ,  14  are positioned apart from each other in the erected position at a predetermined distance, that is, the length of each shelf. Each shelf has its sections  24 ,  26  co-planar in a load-bearing state. The rear wall  16  is planar. Also shown is a top wall  40  hinged along linear edge  42  to the outer wall  14   a , and having a top flap  44  hinged along linear edge  46  and inserted into the space between the inner and outer walls  12   b ,  12   a.    
   In order to collapse the structure, the top flap  44  is removed from its position between the walls  12   b ,  12   a , and the side walls  12 ,  14  are brought closer together, as shown in FIG.  1 . Each shelf section  24 ,  26  folds about its respective fold line  22  which extends along the entire width of the shelf. In the fully collapsed position, each shelf section  24 ,  26  touches each other, and the side walls touch the shelf sections. The top wall  40  is folded back to overlie the side wall  14 . 
   Each shelf  20  has upper shelf wall portions  54 ,  56  separated by a non-linear slit  50  extending therethrough. The slit  50  is curvilinear, and wall portion  54  is formed with upper projections  58 ,  60 . Wall portion  56  is formed with upper projection  62  located between the projections  58 ,  60 . In the erected position, the projection  62  nests closely between the projections  58 ,  60  and, indeed, the adjacent edges of wall portions  54 ,  56  are of complementary interfitting contour. It will also be noted that projections  58 ,  60  longitudinally extend in one direction across and past the respective fold line, and that projection  62  likewise longitudinally extends across and past the fold line, but in an opposite direction. 
   Each shelf  20  has lower shelf wall portions  64 ,  66  (see  FIG. 3 ) directly underneath the upper shelf wall portions  54 ,  56  and separated by a non-linear slit  68 . The slit  68  is preferably curvilinear, and wall portion  64  has a lower projection  70 , and wall portion  66  has a pair of lower projections  72 ,  74  between which the projection  70  nests closely in the load-bearing state of the shelf. Lower projection  70  lies underneath upper projection  62 , and the projections  62 ,  70  extend in opposite directions across and past the fold line. Lower projections  72 ,  74  lie underneath upper projections  58 ,  60 , and each such pair of projections extends in opposite directions across and past the fold line. 
   Each shelf also has a base layer  80  glued to the underside of the lower shelf wall portions  64 ,  66 . The base layer  80  is not slit like the upper shelf wall portions  54 ,  56  or the lower shelf wall portions  64 ,  66 . Instead, the base layer has base portions  84 ,  86  which are foldable about the fold line  22 , which is a crease extending linearly along the entire width of the shelf. The base layer  80  supports the upper and lower shelf wall portions from below. Preferably, the base layer is a corrugated board material having a fluted layer and an outer liner. The fluted layer may be slit, but the slit does not extend through the outer liner. 
   For increased rigidity, the rear edge of each shelf has upper and lower tabs  90 ,  92  integral with the upper shelf wall portions  54 ,  56  and with the base layer  80 . The juxtaposed tabs  90 ,  92  are inserted into a locking hole  94  extending through the rear wall  16  and aid in supporting the shelf at its weakest region, i.e., at its center and on the fold line  22 . A pair of upstanding tabs  96 ,  98  on an upper edge of the rear wall  16  assists in enabling another shelving structure to be stacked on top of the structure  10 . 
   It will be understood that each of the elements described above, or two or more together, also may find a useful application in other types of constructions differing from the types described above. 
   While the invention has been illustrated and described as embodied in an erectable shelving structure, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention. 
   Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims. 
   What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims.