Abstract:
A paperboard carton blank is formed into a carton from an integral sheet of foldable material, such as paperboard. The carton includes a number of sides serially connected to one another each having a top end spaced from a bottom end. A number of top and bottom flaps are each foldably connected to the top and bottom end, respectively, of one of the sides and the associated flaps combine to form top and bottom ends of the carton. One or more struts extend beyond the distal ends of at least some of the top or bottom flaps and are folded into face to face juxtaposition and secured onto an inside face of the side associated with the flap to which it is connected to thereby reinforce the associated side and inhibit deformation of the carton.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates generally to the packaging art and, more particularly, to a carton that is economical to manufacture and robust in use. 
     In recent years, a variety of consumer boxes and cartons have been developed for packaging, shipping, storing, carrying, and dispensing a variety of products. An example of such packages is a carton for carrying beverages or food products. A typical container for such products may often be formed from a paperboard carton blank. Carton manufacturers often face the challenge of providing a carton having an ergonomic construction that is sufficiently strong to withstand the stress generated by the weight of articles enclosed therein and various shipping and storage arrangements. One approach to resolving this quandary is to construct the carton from a stronger material such as paperboard or from a sheet of material of a relatively higher caliper. As fully enclosed cartons typically have six walls (top, sides, bottom, and ends) that are formed from a single sheet of material, and cost tends to increase according to the strength and thickness of material used to construct the carton walls, this approach is an expensive one because it effectively amounts to reinforcing all of the walls of the carton irrespective of the relative magnitude of the forces borne by each wall or portion of the carton. 
     According to another approach, additional material is applied to or around various areas of the carton as needed to increase its integrity. However, it is not desirable to form a carton from multiple sheets of material during production, construction and manufacture because the logistics of attaching additional components to a carton blank during processing on high speed production lines is problematic. 
     It has been difficult, however, to provide an economical carton which combines the requisite strength for handling, transport and storage and at the same time offers convenient and economical manufacturing techniques. 
     What is needed is a carton that is formed from a single blank, and which provides a reinforced areas integrated into the carton blank so that the carton walls are efficiently constructed without wasting expensive material in areas of the carton that are less likely to fail. 
     Therefore, an improved carton and carton blank is needed that satisfies these and other shortcomings associated with known carton designs. 
     SUMMARY OF THE INVENTION 
     This invention solves these and other problems and, in one embodiment, includes a paperboard carton blank, in another embodiment is a carton formed from the carton blank and in a still further embodiment is a method of constructing such a carton. Briefly, the sleeve style carton is formed from a paperboard blank into a tubular configuration with open ends. The end panels are formed from flaps which extend from the various sides, top and bottom panels of the carton. The flaps are folded onto each other and form a composite end panel. 
     In some applications, the formed carton is filled and stacked on its end with the composite end panels being on the top/bottom. To increase the compression strength of the carton in this upright configuration, this invention includes reinforcing struts attached to the distal end of each flap. The struts are folded into face-to-face juxtaposition on the respective sides of the carton and adjacent to the associated fold line joining the flap to the end of the side panel. The struts are folded onto and glued to the associated side panel. This provides added strength to the carton when it is erected and stacked on its end in an upright configuration to inhibit the side panels from being crushed in those areas. An oval or other shaped hole may be provided at the juncture of the strut and the flap on the side panels of the carton to facilitate folding and avoid binding of the carton blank material. With the struts, thinner and often less expensive paperboard can be used to make the carton blank while still providing adequate strength to avoid deformation of the carton. 
     A carton of one embodiment is formed from a single, integral sheet of foldable material, such as paperboard. The carton includes a number of sides serially connected to one another and each of the sides has a top end spaced from a bottom end. A number of top flaps are each foldably connected to the top end of one of the sides and the top flaps combine to form a top end of the carton. Similarly, a number of bottom flaps are each foldably connected to the bottom end of one of the sides and the bottom flaps combine to form a bottom end of the carton. 
     One or more struts extend from the distal ends of at least some of the top or bottom flaps and are folded into face to face juxtaposition and secured onto an inside face of the side associated with the flap to which it is connected to thereby reinforce the associated side and inhibit deformation of the carton. The carton construction and associated struts are particularly advantageous to resist buckling, crushing or deformation of the carton from a longitudinal direction and when the cartons are filled and stacked one on top of another for storage, display or shipping. 
     In a further embodiment, each strut is connected to the associated flap by a bridge and the bridge is integrally joined with the associated strut and flap. The strut may be directly adjacent to the associated flap to which it is connected when the strut is secured to the associated side of the carton. 
     In a still further embodiment, a hole in the sheet of material adjacent to the strut and positioned at a juncture between the flap to which the strut is connected and the associated side advantageously inhibits binding of the sheet of material when the flap is folded relative to the associated side. The carton may have a strut connected to each of the flaps on the top and bottom ends to provide added strength to the carton to resist deformation and buckling. 
     Due at least in part to the robust character of the carton with the reinforcing struts according to various embodiments of this invention, the paperboard used to construct the carton may be thinner than prior paperboard carton blanks while still providing a robust and crush resistant carton formed from a more economically efficient carton blank. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above-mentioned and other features and advantages of this invention, and the manner of attaining them, will become more apparent and the invention itself will be better understood by reference to the following description of embodiments of the invention taken in conjunction with the accompanying drawings, wherein: 
         FIG. 1  is a plan view of a carton blank according to one embodiment of this invention; 
         FIG. 2  is a perspective view of the carton blank of  FIG. 1  with reinforcing struts connected to various flaps on the carton blank being folded as shown by the arrows; 
         FIGS. 3-5  are sequential views of the carton blank of  FIGS. 1-2  being folded into a closed ended carton; 
         FIG. 6  is a perspective view of the carton formed from the carton blank of  FIG. 1 ; 
         FIG. 7  is a cross-sectional view taken along line  7 - 7  of  FIG. 5  showing the position of some of the struts in the open ended carton; 
         FIG. 8  is a plan view of a carton blank according to another embodiment of this invention; 
         FIG. 9  is a perspective view of the carton blank of  FIG. 8  with reinforcing struts connected to various flaps on the carton blank being folded as shown by the arrows; 
         FIGS. 10-12  are sequential views of the carton blank of  FIGS. 8-9  being folded into a closed ended carton; 
         FIG. 13  is a perspective view of the carton formed from the carton blank of  FIG. 8 ; and 
         FIG. 14  is a cross-sectional view taken along line  14 - 14  of  FIG. 12  showing the position of some of the struts in the open ended carton of this embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to  FIG. 1 , one embodiment of a carton blank  10  according to this invention is shown. The carton blank  10  is suitable for forming into a carton  12  as shown in  FIG. 6 . The carton blank  10  according to various embodiments of this invention is formed from a single sheet of paperboard which may be 0.028 inches thick of a custom kote paperboard or another type of paperboard or other material as is appropriate within the scope of this invention. The various components, elements and features of the carton blank  10  are integrally formed with each other and the blank  10  is typically stamped or cut from a single sheet of paperboard or other material. 
     The carton blank  10  includes a number of serially connected sides or side panels  14 ,  16 ,  18 ,  20 , four of which are shown in the carton blank  10  of  FIG. 1 . In the particular embodiment of the carton blank  10  shown in  FIG. 1 , each side  14 ,  16 ,  18 ,  20  has a generally rectangular configuration in which a top end  14   a ,  16   a ,  18   a ,  20   a  of the side as shown in  FIG. 1  is spaced longitudinally from a bottom end  14   b ,  16   b ,  18   b ,  20   b  of the respective side. A series of three spaced and longitudinally extending side fold lines  22 ,  24 ,  26  are each positioned between a pair of adjacent sides as shown in  FIG. 1  to allow the sides  14 ,  16 ,  18 ,  20  to be folded relative to one another when erecting the carton  12  from the carton blank  10 . A side flap  28  is joined to the lateral outer edge of one of the sides  14  via a side fold line  30 . The side flap  28  includes a glue strip  32  which attaches the side flap  28  to an inner face of the opposite side  20  to form the carton blank  10  into a tubular configuration ( FIG. 4 ) while the carton  12  is being erected from the blank  10 . In one embodiment, the strength of the carton  12  and blank  10  is increased by orienting the grain of the paperboard in a generally longitudinal direction extending between the top and bottom ends of the sides. 
     As shown in  FIG. 1 , the carton blank to includes a number of top flaps  34 ,  36 ,  38 ,  40 , each of which is connected to the top end  14   a ,  16   a ,  18   a ,  20   a  of one of the sides  14 ,  16 ,  18 ,  20  via a laterally extending flap fold line  42 ,  44 ,  46 ,  48 . Similarly, a number of bottom flaps  50 ,  52 ,  54 ,  56  are each attached to the bottom end  14   b ,  16   b ,  18   b ,  20   b  of the associated sides  14 ,  16 ,  18 ,  20  via a laterally extending flap fold line  58 ,  60 ,  62 ,  64 . The top flaps  34 ,  36 ,  38 ,  40  combine to form a top  66  of the erected carton  12  when each top flap is folded about the associated flap fold line  42 ,  44 ,  46 ,  48  to be generally perpendicular to the respective side as shown generally in  FIG. 6 . Similarly, the bottom flaps  50 ,  52 ,  54 ,  56  combine to form a bottom  68  of the carton  12  when each bottom flap is formed to be generally perpendicular about the associated fold line  58 ,  60 ,  62 ,  64  to the respective side. 
     According to various embodiments of this invention, a strut  70 ,  72 ,  74 ,  76 ,  78 ,  80 ,  82 ,  84  is connected to the distal terminal edge of each top flap  34 ,  36 ,  38 ,  40  and each bottom flap  50 ,  52 ,  54 ,  56 . While the carton blank  10  of  FIG. 1  shows a strut connected to each top and bottom flap, those of ordinary skill in the art will appreciate that other arrangements and configurations of the carton  12  and associated carton blank  10  are possible within the scope of this invention in which the struts are only on the top flaps or the bottom flaps or only on selected top or bottom flaps. Each strut  70 ,  72 ,  74 ,  76 ,  78 ,  80 ,  82 ,  84  may be connected to the respective flap via a bridge  70   a ,  72   a ,  74   a ,  76   a ,  78   a ,  80   a ,  82   a ,  84   a . Referring to  FIG. 1 , the bridges  70   a ,  78   a  associated with the top and bottom flaps  34 ,  50  are narrow elements attached to the respective flap  34 ,  50  at the outer lateral edge of the flap. Other embodiments of the bridges  72   a ,  76   a ,  80   a ,  84   a  shown in  FIG. 1  extend substantially the entire width of the associated strut  72 ,  76 ,  80 ,  84  and associated flap  36 ,  40 ,  52 ,  56 . In still other embodiments, the strut  74 ,  82  is connected to the carton blank  10  via the adjacent struts  72 ,  76  and  80 ,  84  associated with the respective flaps and sides such that flaps  38 ,  54  do not have a bridge folded thereon when the carton is erected (see  FIGS. 3-5 ). Each bridge  70 ,  72 ,  76 ,  78 ,  80 ,  84  is connected to the respective flap  34 ,  36 ,  40 ,  50 ,  52 ,  56  via a bridge fold line  70   b ,  72   b ,  76   b ,  78   b ,  80   b ,  84   b . Each strut is joined to the adjacent strut via a strut fold line  70   c ,  72   c ,  74   c ,  80   c ,  82   c ,  84   c . The struts  72 ,  76 ,  80 ,  84  which extend substantially the entire width of the associated flap  36 ,  40 ,  52 ,  56  each include a fold line  72 ,  76   d ,  80   d ,  84   d  extending laterally between the flap and the strut. Coincident with the fold line  72   d ,  76   d ,  80   d ,  84   d  is a hole  86 ,  88 ,  90 ,  92  which may be rectangular, oval or of another configuration and the purpose and function of the hole  86 ,  88 ,  90 ,  92  will be described later herein. A series of glue lines  94  are positioned proximate the top and bottom ends  14   a ,  16   a ,  18   a ,  20   a ,  14   b ,  16   b ,  18   b ,  20   b  of each side  14 ,  16 ,  18 ,  20  which will secure the associated strut  70 ,  72 ,  74 ,  76 ,  78 ,  80 ,  82 ,  84  to the side as will be described later herein. 
     Referring to  FIGS. 2-5 , one embodiment of the method for erecting the carton  12  from the carton blank  10  of  FIG. 1  is shown. Initially as shown in  FIG. 2 , the struts  70 ,  72 ,  74 ,  76  associated with the top  66  of the carton  12  are folded downwardly in the direction of arrow A and likewise the struts  78 ,  80 ,  82 ,  84  associated with the bottom  68  of the carton are folded upwardly (arrow B) as shown in  FIG. 2 . Referring to  FIG. 3 , the struts  70 ,  72 ,  74 ,  76 ,  78 ,  80 ,  82 ,  84  are adhesively secured to the associated side  14 ,  16 ,  18 ,  20  via the respective glue lines  94  on the sides  14 ,  16 ,  18 ,  20 . The struts are positioned on the sides immediately adjacent to the respective flap fold line  42 ,  44 ,  46 ,  48 ,  58 ,  60 ,  62 ,  64  and the fold lines  72   d ,  76   d ,  80   d ,  84   d  joining the respective strut  72 ,  76 ,  80 ,  84  to the bridge  72   a ,  76   a ,  80   a ,  84   a  that is coincident with the hole  86 ,  88 ,  90 ,  92  is likewise positioned coincident to the associated flap fold line  44 ,  48 ,  60 ,  64 . The holes  86 ,  88 ,  90 ,  92  are provided and positioned coincident with the associated flap fold line so that when the respective flap is folded to form the top or bottom of the carton, the blank material does not bind or inhibit the free-folding operation of the flap. 
     As shown by arrows C and D in  FIG. 3 , the sides  14 ,  16 ,  18 ,  20  are folded about the side fold lines  22 ,  24 ,  26  and the side flap  28  is folded about the side flap fold line  30  so as to be generally perpendicular relative to the adjacent sides. The glue line  22  on the side flap  28  adheres the side flap  28  to the opposite side  20  thereby forming the carton blank to into a tubular configuration as shown generally in  FIG. 4 . The bottom flaps  50 ,  52 ,  54 ,  56  are folded inwardly in the direction of arrows E and F so as to form the bottom  68  of the carton  12 . Appropriate glue deposits or strips (not shown) are utilized to secure the bottom flaps  50 ,  52 ,  54 ,  56  together to form the bottom  68  of a carton  12 . As shown in  FIG. 7 , the open top end of the carton  12  may be filled with carton contents and then the top flaps  34 ,  36 ,  38 , are folded inwardly to form the top  66  of the carton  10 . Once again, as shown in  FIGS. 4 and 5 , each hole  86 ,  88 ,  90 ,  92  adjacent the associated strut  72 ,  76 ,  80 ,  84  is aligned with and coincident to the respective flap fold line  44 ,  48 ,  60 ,  64  so that when the flap is folded inwardly to form the top or bottom of the carton, the strut and associated bridge do not bind or restrict movement of the flap  36 ,  40 ,  44 ,  48 . 
     The cross-sectional view taken along line  7 - 7  of  FIG. 5  shows the struts in  FIG. 7  being positioned adjacent to the top and bottom  66 ,  68  of the carton  12  so that after the carton  12  is loaded, the struts  70 ,  72 ,  74 ,  76 ,  78 ,  80 ,  82 ,  84  provide added strength to resist buckling and deformation of the carton  12  in the associated regions. This affords the opportunity to stack multiple cartons  12  vertically one atop another and the struts inhibit damage, deformation of buckling of the carton  12 . As such, a robust carton  12  is provided and may be formed from the carton blank  10  of thinner paperboard or other material thereby benefiting the carton  12  from a more economical carton blank  10  which still provides the requisite strength and resistance to buckling and deformation. 
     Referring to  FIGS. 8-13 , an additional embodiment of this invention is shown and the features, elements and components of this embodiment, which are similar or comparable to elements in the embodiment of  FIGS. 1-7 , are indicated by similar reference numerals in the  100  series of numbers.  FIG. 8  shows a carton blank  110  including the sides  114 ,  116 ,  118 ,  120 , associated side fold lines  122 ,  124 ,  126 , side flap  128  and associated side flap fold line  130  and the top and bottom flaps  134 ,  136 ,  138 ,  140 ,  150 ,  152 ,  154 ,  156 . Struts  170 ,  172 ,  174 ,  176 ,  178 ,  180 ,  182 ,  184  are connected to the respective flaps via bridges  170   a ,  172   a ,  176   a ,  178   a ,  180   a ,  184   a  and the various components are secured one to another via glue lines  194  as indicated in  FIG. 8 . One feature of the carton blank  110  of  FIG. 8  which is distinguishable from the carton blank  10  of  FIG. 1  is that the respective struts are separated from adjacent struts via gaps  200  or cut lines  202  unlike the fold lines which join the adjacent struts together in the carton blank  10  of  FIG. 1 . The construction and erection of the carton  112  from the carton blank  110  is shown sequentially in  FIGS. 9-12  resulting in the erected filled carton  112  as shown in  FIG. 13 . A cross-sectional view of the interior of the carton  112  is shown in  FIG. 14 . The embodiment of  FIGS. 8-14  is tailored to a pre-formed or pre-glued carton  112  rather than a carton blank which does not have the glue strips on it and the glue is added during the formation of the carton. 
     From the above disclosure of the general principles of the present invention and the preceding detailed description of at least one preferred embodiment, those skilled in the art will readily comprehend the various modifications to which this invention is susceptible. Therefore, I desire to be limited only by the scope of the following claims and equivalents thereof.