Abstract:
The invention provides a nestable box spring foundation having a generally rectangular perimeter divided into a plurality of rectangular openings by a grid of longitudinally and laterally extending wires. Support is provided by a pair of generally U-shaped wire members mounted at their ends to adjacent grid wires. The members are of simple configuration and accordingly inexpensive to manufacture, simple to attach such as by welding and by virtue of their symmetry provide good lateral strength.

Description:
FIELD OF THE INVENTION  
       [0001]     This invention relates generally to bedding. More specifically this invention relates to box spring foundations, and in particular to nestably stackable box spring foundations.  
       BACKGROUND TO THE INVENTION  
       [0002]     In the past, box spring foundations comprised a pair of generally rectangular border wires which were spaced apart by coil or bent wire spring modules. A problem with such earlier designs is that they are bulky to ship to a bedding manufacturer for securement to a slat base and the application of padding and covering. The bulkiness results from having an open wire structure with no capability of nestable stacking.  
         [0003]     Early foundation designs were resiliently collapsed (compressed) for shipping and held in the collapsed state with ties. This however required both the application and removal of ties which is both time consuming and wasteful. Furthermore, such a degree of resiliency may be undesirable at least in some applications.  
         [0004]     In order to avoid having to compress and restore a foundation, later designs provided for either nestably stackable configurations or hingedly collapsible arrangements. U.S. Pat. Nos. 5,346,188 to Rodgers et al and 5,622,357 to Schulz Jr. et al are examples of a folding arrangement. U.S. Pat. Nos. 6,484,339B2 to Mossbeck et al and 5,967,499 to McGraw et al are examples of the latter arrangement.  
         [0005]     The foregoing designs each have shortcomings. The hingedly collapsible arrangements tend to be more complex as hinging must be provided to enable collapse. Once erected however hinging is no longer desirable as it affects the inherent lateral stability of the design. Some of the nesting designs have complicated (and therefore more difficult and costly to manufacture) support elements. Others are less laterally stable than might be desirable. Still others have relatively labour intensive attachment arrangements for connecting the structural elements.  
         [0006]     Objects of the present invention include providing a nestably stackable box spring foundation which is simple to manufacture, cost effective and robust.  
       SUMMARY OF THE INVENTION  
       [0007]     In very general terms, the invention provides a nestable box spring foundation having a generally rectangular perimeter divided into a plurality of rectangular openings by a grid of longitudinally and laterally extending wires. Support is provided by a pair of generally U-shaped wire members mounted at their ends to adjacent grid wires. The members are of simple configuration, inexpensive to manufacture, simple to attach such as by welding and, by virtue of their symmetrical pyramidal shape, provide good lateral strength.  
         [0008]     More particularly, a nestable box spring foundation is provided which has a generally rectangular perimeter frame and a grid having longitudinally and laterally extending grid wires secured at opposite ends to the perimeter frame to define a plurality of generally rectangular openings across the perimeter frame. The foundation has generally U-shaped support members each having a pair of legs joined at respective base ends thereof to a base member and spaced apart at respective outer ends thereof opposite the respective base ends. The support members are mounted in pairs within at least some of the openings with the outer ends being secured to the grid wires and the base ends of the pairs adjacent, to define a plurality of open, generally pyramidal supports opening toward but extending away from the grid for supporting the grid and in turn the perimeter frame. The supports are nestable in corresponding supports of an adjacent nestable box spring foundation.  
         [0009]     The support members may be mounted in the aforesaid pairs in alternate of the rectangular openings.  
         [0010]     The legs of the support members may diverge toward the outer ends and the outer ends may be secured either to the longitudinally extending grid wires or to the laterally extending grid wires.  
         [0011]     The perimeter frame may have opposite sides and opposite ends. The longitudinally extending grid wires may be generally parallel to the sides and the latterly extending grid wires may be generally parallel to the ends.  
         [0012]     The grid wires may be secured to one another and to the perimeter of the frame by welding. The outer ends of the legs may be secured to the grid wires by welding.  
         [0013]     The legs of the support members may bend towards the grid wires to which they attach adjacent their outer ends.  
         [0014]     The support members may attach to the longitudinally extending grid wires.  
         [0015]     Characterized in another way, a nestably stackable box spring foundation is provided which has a generally rectangular perimeter frame having opposite sides and opposite ends. The foundation further has a grid having longitudinally and laterally extending wires to define grid openings, the longitudinally extending wires being generally parallel to the sides and secured to the ends, the laterally extending wires being generally parallel to the ends and secured to the sides. A plurality of nestable supports extend away from the grid to support the grid and in turn the perimeter frame. The supports further have a pair of generally U-shaped support members each of the generally U-shaped support members having a pair of legs extending away from respective adjacent base portions toward respective outer ends thereof and each of the generally U-shaped support members being attached at its respective outer ends to a different one of an adjacent pair of the laterally extending or the longitudinally extending wires.  
         [0016]     The supports may be arranged in rows and columns with adjacent of the supports being spaced apart from each other by a grid opening.  
         [0017]     The legs of each support member may diverge from the base toward the outer ends. The legs and support members may be bent adjacent their outer ends toward the wires to which they attach.  
         [0018]     The grid wires may be secured to one another and the perimeter frame by welding and the outer ends may be attached to the wires by welding. 
     
    
     DESCRIPTION OF DRAWINGS  
       [0019]     Preferred embodiments of the invention are described in detail below with reference to the accompanying illustrations in which:  
         [0020]      FIG. 1  is a perspective view from above of a nestable box spring foundation according to the present invention;  
         [0021]      FIG. 2  is a top plan view corresponding to  FIG. 1 ;  
         [0022]      FIG. 3  is a side elevation corresponding to the arrow  3  in  FIG. 1 , the view would be the same from either side;  
         [0023]      FIG. 4  is an end elevation corresponding to the arrow  4  in  FIG. 1 , the opposite end would appear similar;  
         [0024]      FIG. 5  is a partial sectional view on line  5 - 5  of view  FIG. 3  showing two of the units in the process of being stacked;  
         [0025]      FIG. 6  is a partial sectional view on line  6 - 6  of  FIG. 3  showing two of the units in the process of being stacked; and,  
         [0026]      FIG. 7  is a perspective view of one embodiment of a generally U-shaped support member according to the present invention. 
     
    
     DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0027]     A nestable box spring foundation according to the present invention is generally indicated by reference  10  in the accompanying illustrations. The nestable box spring foundation has a generally rectangular perimeter frame  12  having opposite sides  14  and opposite ends  16 . A grid  20  is secured to the frame. The grid has longitudinally extending wires  22  and laterally extending wires  24 . The longitudinally extending wires  22  extend between and are secured to the opposite ends  16  and run generally parallel to the opposite sides  14 . The laterally extending wires  24  extend between and are secured to the opposite sides  14  and run generally parallel to the opposite ends  16 .  
         [0028]     Generally U-shaped support members  30  are provided in pairs to define nestable supports  40 . The nestable supports  40  are secured to the grid  20  to support the grid and in turn the perimeter frame  12  above an underlying surface. Each of the U-shaped members  30  has a pair of legs  32  joined at respective base ends  34  to a base member  36 . The legs  32  further have outer ends  38  opposite the base ends  34  which are spaced apart.  
         [0029]     The generally U-shaped support members  30  would typically each be bent from a single piece of wire. Securement to the grid would be typically by welding, such as spot welding to the grid wires. In order to facilitate welding and improve resiliency, the legs  32  may bend toward the grid wires as illustrated at  42 .  
         [0030]     The pair of generally U-shaped members  30  in the nestable supports  32  need not be attached at the respective base portions  36  although they may be should this be desired. Generally the nestable box spring foundation  10  will be secured to a base member having wooden slats (not illustrated) with the base portions  36  stapled or otherwise secured to the slats. Accordingly, the base portions  36  may be held in alignment through further securement to a slat rather than by direct connection one to the other.  
         [0031]     The legs  32  diverge from each other from the base end toward the outer end and accordingly the resulting nestable supports  40  generally resemble a pyramid, albeit flattened at one end. Although the expression “generally U-shaped” is utilized it is not intended to be limiting. The structures illustrated may also be considered at a “flattened V”. Generally what is intended is a structure that has two legs  32  which are either parallel or diverging with the legs joined at one end and having spaced apart ends opposite the joined end. The expression “joined” does not require that the members be made up of individual parts, but may define a structure which is continuous and which may, as suggested above, be formed by bending.  
         [0032]     Various arrangements exist for joining wire in box spring foundations. Although most of these could be used in the present arrangement, from the standpoint of maximizing manufacturing speed and minimizing cost it is expected that welding will be utilized. Other methods may include the use of clips or winding one of the wires about another.  
         [0033]     The structure of the box spring foundation  10  is illustrated as having the ends  38  of the generally U-shaped members  30  secured to the longitudinally extending wires  22 . While this is a present and preferred embodiment, the nestable supports  40  may be rotated 90 degrees from what is illustrated to have the ends  38  secured to the laterally extending grid wires  24 .  
         [0034]     It is generally not necessary to have a nestable support  40  beneath each of the grid openings  26 . Accordingly the nestable supports  40  would typically be spaced apart by one grid opening both longitudinally and laterally. Longitudinal spacing would generally be a function of the slat spacing of the underlying frame (not illustrated). Lateral spacing would generally be determined by the number of grid openings which in turn would be a function of the desired degree of rigidity balanced with minimizing material usage.  
         [0035]     Nestable stacking of the box spring foundations  0  is illustrated in  FIGS. 5 and 6  and is made possible by virtue of the open grid structure and pyramidal upwardly opening nestable supports  40  and the grid openings  26 .  
         [0036]     The generally U-shaped support members  30 , the longitudinally extending grid wires and laterally extending wires  24  may be made from wire having a similar thickness. This may for example be (without being limiting), steel wire having a gauge of from 10 to 6, with 10 gauge presently being preferred from a cost versus strength consideration.  
         [0037]     Although not entirely necessary, it is generally expected that the rectangular perimeter frame  12  will be of a heavier gauge material than the grid  20  and the nestable supports  40 . Generally stiffness is expected from the rectangular perimeter frame whereas the grid  20  and nestable supports  40  preferentially have more resiliency in order to maximize comfort. Accordingly, by way of example (without being limiting), the perimeter frame may be steel wire of from 3 to 6 gauge with 6 gauge presently being preferred.  
         [0038]     The above description is intended in an illustrative rather than a restrictive sense and variations to the specific structure as described may be apparent to those skilled in the art without departing from the invention which is defined in the claims set out below.  
       PARTS LIST  
       [0039]    
       
         
               
               
               
             
           
               
                   
                   
               
               
                   
                   
               
             
             
               
                   
                 10 
                 nestable box spring foundation 
               
               
                   
                 12 
                 rectangular perimeter frame 
               
               
                   
                 14 
                 sides (of frame) 
               
               
                   
                 16 
                 ends (of frame) 
               
               
                   
                 20 
                 grid 
               
               
                   
                 22 
                 longitudinally extending wires 
               
               
                   
                 24 
                 laterally extending wires 
               
               
                   
                 26 
                 grid openings 
               
               
                   
                 30 
                 generally U-shaped member 
               
               
                   
                 32 
                 legs 
               
               
                   
                 34 
                 base end of legs 
               
               
                   
                 36 
                 base portions 
               
               
                   
                 38 
                 outer end of legs 
               
               
                   
                 40 
                 nestable support 
               
               
                   
                 42 
                 outwardly bent ends