Abstract:
A box blank for a pizza carton or other food carton that comprises one or more of the following features: (1) a structure that enables multiple blanks to be mated end-to-end for a material savings, (2) a rigidizing fold line structure for connecting a flap to a wall panel in a way that minimizes flap movement during box blank manuf acture, and (3) a frictionizing slot-forming slit that creates a tight-gripping cover flap receiving slot in the erected carton.

Description:
FIELD OF THE INVENTION 
     This invention relates to packaging in general and in particular to box blanks for pizza cartons and other food cartons made of semi-rigid, foldable material. 
     BACKGROUND OF THE INVENTION 
     In the pizza and food-to-go industries there are numerous types of cartons made of foldable material. Perhaps the most prevalent of these materials is corrugated paperboard. Cartons made of corrugated paperboard are erected from a flat sheet of material known as a box blank, or blank, for short. 
     At least three problems exist with many of the current types of blanks used for pizza and food cartons. First, the blank can require a relatively large amount of material, particularly the blanks for those cartons that utilize the traditional double-panel, or roll-over, front wall structure. 
     Second, during manufacture, corner flaps attached to the ends of side walls at a fold line tend to bend at the fold line as the blanks are released from the cutting dies and as they proceed down the production line. This is especially the case with blanks made of thinner types of corrugated paperboard, such as E-flute and F-flute. A folded, or unaligned, flap can cause problems in production, sometimes requiring the production line to be slowed down or stopped. 
     Third, some blanks use a cover-locking structure that involves inserting a cover front flap into a flap-receiving slot in the front wall of the carton. In order for the slot to tightly grip the cover flap, the slot must be relatively narrow in the front-to-back, or width-type, dimension. However, with this configuration it can be difficult and time-consuming to fit the cover flap into the slot. To make it easier to quickly fit the cover flap into the slot, a wider flap-receiving slot can be used. However, when this is done the slot often fails to tightly grip and hold the cover flap in place, particularly after the carton has been opened and then re-closed. 
     Regarding the first problem (i.e., use of excessive material for making the blank), box manufacturers have designed the structure of box blanks so that multiple side-by-side blanks mate, or nest, together during the die-cutting phase of manufacture. This reduces the amount of material needed for manufacture of each blank. The process of mating adjacent blanks has been used as a material-reduction technique for the last hundred years or so. As a result, hundreds of mated side-by-side arrangements of multiple blanks have been invented. However, no arrangement has been created that accommodates the typical structure of a pizza carton or food carton. That structure comprises a bottom panel, a rear wall attached to the bottom panel, a cover panel attached to the rear wall, a cover front flap attached to the front edge of the cover panel, and a front wall structure opposing the rear wall and comprising a front wall and an ancillary panel structure attached to the front wall. So there has remained a need for a mating arrangement for typical food carton box blanks that effects a savings of material in manufacture of the blanks. 
     Regarding the second problem (i.e., the folding or misalignment of corner flaps during blank manufacture), the typical solution has been to create a “tack,” or narrow strip of material, between the flap and an adjacent panel of the blank. However, this requires the end-user to have to take the time to break the “tack” before erecting the blank into a box. As a result, there has remained a need for “rigidized” corner flaps on a box blank without resorting to the inconvenient “tack.” The typical fold line used for connecting a corner flap to a, wall panel consists of either (a) a score (i.e., crease) in the board or (b) a series of aligned slits, sometimes referred to as a perforation line, or perf line. A fold line of aligned slits usually takes the form of either one-quarter inch slits separated by a one-quarter inch score or one-eighth inch slits separated by a one-eighth inch score. There has been no inventive prior art pertaining to fold line structure. So there has remained a need for a fold line structure that results in rigidizing or holding corner flaps in place during manufacture of the blank. 
     Regarding the third problem (i.e., lack of a slot-forming structure that results in a flap-receiving slot that&#39;s both easy to insert the cover flap into and tight-gripping enough to hold the flap within the slot once it&#39;s inserted), as regards double-panel wall structures where an inner wall panel is disposed parallel to an outer wall panel, there has been no inventive prior art pertaining to cover flap receiving slots. So there has remained a need for a slot-forming structure that results in a flap-receiving slot that is both easy to use and tight-gripping of the cover flap. 
     Accordingly, it would be highly desirable to provide a box blank that overcomes one, two, or all three of the above-described problems. None of the three problems have been solved by the prior art, but they are solved by my invention. 
     SUMMARY OF THE INVENTION 
     My invention is a box blank that provides one or more of the following three features: 
     1. End-to-end mating of multiple blanks wherein a cover front flap of a first blank is disposed within a notch in the front wall structure of a second blank, thereby effecting a savings of material; 
     2. A rigidizing fold line used in attaching a flap to an end of a wall panel, wherein the rigidizing fold line comprises at least one indentation portion and at least one non-indentation portion, thereby reducing movement of the flap while in the manufacturing process; and 
     3. A frictionizing slot-forming slit disposed within a multi-panel wall structure of a box blank, wherein the frictionizing slot-forming slit has a central-slit portion and at least one end-slit portion that&#39;s disposed at an obtuse angle to the central-slit portion, thereby providing for a trapezoidal-shaped flap-receiving slot with an acutely angled end section in the erected carton, and which, in turn, enables the slot to grip, or pinch, the side edge of a cover flap and hold it within the slot. 
     My invention typically would be associated with blanks used for creating cartons for food products; however, it could take other forms for other purposes, as well. 
     A complete understanding of the invention can be obtained from the detailed description that follows. 
     OBJECT AND ADVANTAGES 
     The main object of my invention is (a) a material efficient box blank that&#39;s (b) easy to manufacture and (c) which provides for a cover-locking slot that allows for easy cover flap insertion while also providing a tight grip on the flap. 
     The advantages of my invention are cost savings, production simplicity, and cover closure enhancement on a food carton. 
     Further objects and advantages of the invention will become apparent from consideration of the following detailed description, related drawings, and appended claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a plan view of multiple box blanks of a preferred embodiment of the invention. 
     FIG. 2 is a prior art configuration of a slot-forming slit. 
     FIG. 3 shows a trapezoidal-shape of a flap-receiving slot resulting from the preferred slot-forming slit. 
    
    
     LIST OF REFERENCE NUMERALS 
       10  first blank of the preferred embodiment 
       12  second blank of the preferred embodiment 
       20  bottom panel 
       22  rear wall 
       30  side wall structure 
       32  wall panel 
       34  front corner flap 
       36  rear corner flap 
       38  indentation portion of rigidizing fold line 
       39  non-indentation portion of rigidizing fold line 
       40  front wall structure 
       42  front wall 
       44  ancillary panel structure 
       46  inner wall panel 
       47  width of notch 
       48  connector strip 
       49  notch 
       50  frictionizing slot-forming slit 
       52  central-slit portion 
       54  end-slit portion 
       56  obtuse angle 
       58  length of slot-forming slit 
       59  width-type dimension of slot-forming slit 
       60  cover 
       62  cover panel 
       64  cover front flap 
       66  side edge of cover front flap 
       68  width of cover front flap 
       70  prior art slot-forming slit 
       72  trapezoidal shape of flap-receiving slot 
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to FIG. 1, there is illustrated a preferred embodiment of the invention in the format of first and second corrugated paperboard blanks in a mated end-to-end arrangement. The intended use for the embodiment is as a food carton. However, it will be appreciated, as the description proceeds, that my invention may be realized in different embodiments and may be used in other applications. 
     FIG. 1 shows a first box blank  10  and a second box blank  12 . For simplicity, only a partial section of blank  12  is shown. However, it is to be understood that the remaining (unshown) structure of blank  12  is the same as that of blank  10 . Therefore, whatever is shown and described pertaining to blank  10  also applies to blank  12 . 
     Further, it is noted that the blanks are bilaterally symmetrical. Therefore, pairs of opposing like components are to be found, with one item of the pair on each side of the blank. For simplicity of labeling, each component of the opposing pair will have the same reference numeral. Also, a pair may be indicated by a numeral on one side of the drawing only. Where this occurs, it is to be understood that the discussion also applies to the corresponding component on the other side, even though that component may not be numerically labeled. 
     Referring now to blank  10 , there is a bottom panel  20 , a rear wall  22  hingedly attached to bottom panel  20 , opposing left and right side wall structures  30 , a front wall structure  40  opposing rear wall  22 , and a cover  60 . 
     Cover  60  comprises a cover panel  62  hingedly attached to rear wall  22  and a cover front flap  64  hingedly attached to a front edge of cover panel  62 . Flap  64  has left and right side edges  66  and a width  68 . 
     Side wall structure  30  comprises a wall panel  32  and front and rear corner flaps  34  and  36 , respectively. Each of the corner flaps is attached to the wall panel at a rigidizing fold line. 
     As defined herein, a “rigidizing fold line” is a fold line that comprises at least one indentation portion and at least one non-indentation portion. An “indentation portion” of a fold line is that part of the fold line resulting from some sort of alteration to the board. The typical alterations are (a) a score, or crease, and (b) a perforation line (i.e., series of aligned slits). A “non-indentation portion” of a fold line is that part of the fold line that has no alteration or indentation to the board. 
     As used herein, to qualify as a non-indentation portion, that portion of unaltered board must be at least eight millimeters long. The space that exists between the slits of a perforation line do not qualify as a non-indentation portion of a fold line. In side wall structure  30 , the indentation portions of the rigidized fold line that connects flaps  34 ,  36  to wall panel  32  are designated by the numeral  38 . The non-indentation portion of the fold line is designated by numeral  39  and, even though it has no visible characteristic, it is assumed that it exists in the space between the indentation portions  38 . Non-indentation portion  39  is at least eight millimeters long and, preferably, at least fifteen millimeters long. During manufacture of the blank, non-indentation portion  39  provides rigidity to flaps  34 ,  36  and, thereby, helps to keep them in place, or coplanar with the rest of the blank, during the die-cutting and production process. 
     Front wall structure  40  comprises a front wall  42 , an ancillary panel structure  44 , and a frictionizing slot-forming slit  50 . Ancillary panel structure  44  comprises an inner wall panel  46  and a pair of connector strips  48  that connect wall panel  46  to the top edge of front wall  42 . Along the outer edge of inner wall panel  46  is a notch. The general space created by the notch is indicated by numeral  49 . So, in effect, the notch is designated by numeral  49 . Notch  49  has a width  47 , which happens to be equal to cover flap width  68 . 
     After blank  10  has been erected into a carton, front wall structure  40  constitutes a double-panel wall structure in which front wall  42  is an outer wall panel that&#39;s perpendicular to bottom panel  20 , inner wall panel  46  is an inner panel that&#39;s parallel to front wall  42  and disposed interior to it, and connector strips  48  are perpendicular to the front wall and the inner wall panel. In the carton format, corner flaps  34  are disposed between front wall  42  and inner wall panel  46 . 
     As defined herein, a “slot-forming slit” is a slit in the blank that opens into a flap-receiving slot in the carton after the blank has been erected into a carton. 
     A “frictionizing slot-forming slit” is a slot-forming slit that comprises a central-slit portion and at least one end-slit portion. An “end-slit portion” is a portion of the slit that is disposed at the end of the central-end portion and is at least six millimeters long and disposed at an obtuse angle to the central-slit portion. In frictionizing slot-forming slit  50 , the central-slit portion is designated by numeral  52  and the end-slit portion is designated by numeral  54 . There are a pair of end-slit portions  54 , one at each end of central-slit portion  52  (although only one end-slit portion is labeled). To compare slot-forming slit  50  to a standard slot-forming slit, view FIG. 2 which shows a typical prior art slot-forming slit  70 . 
     Slot-forming slit  50  is disposed between connector strips  48  and is approximately aligned therewith. Further, slot-forming slit  50  has a length  58  and a width-type dimension  59  (which are labeled on blank  12 ). Length  58  is equal to cover flap width  68 . Finally, width-type dimension  59  is at least one and one-half (1.5) times the length of the thickness of the corrugated sheet used for making the blank, and is preferably two times the length of the thickness. So, for example, if the thickness of the corrugated sheet is one-eighth inch thick it is recommended that the width-type dimension of the slot-forming slit (and, hence, also the width of the connector strips) be at least one-fourth inch. This will result in the flap-receiving slot having a width dimension that accommodates easy insertion of the cover flap after the blank has been erected into a carton. As a concluding note, it should be understood that the proportional size of the components shown in the drawing of blank  10  are not necessarily recommended proportional sizes but, to the contrary, are exaggerated proportions provided for the purpose of clear illustration of the invention. 
     When blank  10  is erected into a carton, frictionizing slot-forming slit  50  opens into a flap-receiving slot along the top edge of front wall structure  40 . When viewed from the top, the slot will be of a non-rectangular shape. Specifically, it will be of a trapezoidal shape and contain an acute angle at each end of the trapezoid. The particular shape of the slot will resemble that of trapezoid  72  shown in FIG.  3 . By comparison, when the slot created from prior art slot-forming slit  70  is viewed from the top, it will be of a substantially rectangular shape. When cover flap  64  is inserted into the trapezoidal slot created from frictionizing slot-forming slit  50 , side edges  66  of the flap are pinched within the acute angles at the end of the trapezoidal slot, thereby serving to hold the flap within the slot due to increased friction on the side edges of the cover flap. 
     Mated End-to-end Arrangement 
     As can be seen in FIG. 1, the instant invention accommodates the configuration of multiple blanks ( 10  and  12 ) in a mated end-to-end arrangement. Cover front flap  64  of blank  10  is disposed within notch  49  of blank  12 . In the preferred embodiment, notch  49  is the exact shape of cover front flap  64 . So notch  49  of blank  12  is completely filled by cover front flap  64  of blank  10 . Accordingly, the space associated with notch  49  of blank  12  cannot be labeled in the drawing. (However, the corresponding space associated with notch  49  of blank  10  can be seen.) It should be understood that it&#39;s possible for notch  49  to have a contour different from that of cover flap  64 . If this were to occur, the alternate configuration would still be considered to fall within the scope of the instant invention. In conclusion, the result of this particular mating arrangement is that it effects a savings of material in the manufacture of multiple blanks. 
     Erecting the Blank into a Carton 
     Blank  10  is erected into a carton using the same procedure as employed for erecting a standard square pizza box having a double-panel, or roll-over, front wall. That procedure is essentially as follows. First, fold side wall panels  32  to an upright position and fold front corner flaps  34  inward. Second, fold front wall  42  to an upright position and then fold inner wall panel  46  downward until the outer edge of the panel engages with bottom panel  20  and, thereby, holds panel  46  parallel to front wall  42 . Third, fold rear corner flaps  36  inward. Finally, pull cover panel  62  forward and insert cover front flap  64  into the slot created by slot-forming slit  50 . 
     An Alternate Embodiment of the Invention 
     Other embodiments of the invention are possible. For example, an alternate embodiment can be created by eliminating connector strips  48  in ancillary panel structure  44  and, consequently, attaching inner wall panel  46  directly to front wall  42 . With this arrangement, panel  46  would likely be disposed perpendicular (as opposed to parallel) to front wall  42  after blank  10  has been erected into a carton. 
     Within the drawing of the blank, a fold line between component parts of the invention is depicted with a dashed line. Within the context of this invention, a fold line can be created by a number of means such as, for example, by a crease or score in the board, by a series of aligned spaced short slits in the board, and by a combination of aligned spaced short and long slits. Nonetheless, the entire combination of slits is considered to constitute a single fold line unless otherwise indicated. 
     In conclusion, as referred to herein, a fold line is any line between two points on the blank along which the board is intended to be folded when the blank is being erected into a carton or when the carton is being manipulated as described herein. The type of fold lines shown in the drawings are presently preferred but it will be appreciated that other methods known to those skilled in the art may be used. 
     CONCLUSION, RAMIFICATIONS, AND SCOPE 
     I have disclosed a box blank that provides one or more of the following three features: 
     1. End-to-end mating of multiple blanks wherein a cover front flap of a first blank is disposed within a notch in the front wall structure of a second blank; 
     2. A rigidizing fold line that comprises at least one indentation portion and at least one non-indentation portion; and 
     3. A frictionizing slot-forming slit that has a central-slit portion and at least one end-slit portion that&#39;s disposed at an obtuse angle to the central-slit portion. 
     The illustrated number, size, shape, type, and placement of components represent the preferred embodiment; however, many other combinations and configurations are possible within the scope of the invention. 
     The foregoing discussion has pertained mainly to packaging food products such as pizza, breadsticks, and the like. However, it should be realized that my invention could be used for other purposes, as well. In conclusion, it is understood that the invention is not to be limited to the disclosed embodiments but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims, which scope is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures as is permitted under the law.