Abstract:
A mechanical lock assembly for a wrap-around carton. The mechanical lock assembly has a primary variable lock belt, which both prevents withdrawal of a locking tab after it has been inserted into a locking opening of an associated overlapping panel flap, and enables the lock to adjust according to the size carried items. A secondary locking system prevents the primary locking system from disengaging.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates generally to mechanical locks for holding overlapping flaps of a wrap-around carton in place. More particularly, it relates to a belt lock that provides a variable lock size. 
     2. Prior Art 
     When fabricating a carton from a paperboard blank, opposite ends of the blank are conventionally attached to each other by glue or by a mechanical lock to form the bottom panel of the carton. In the case of a wrap-around carton, flaps located on the ends of the blank typically are overlapped and engaged with one another by mechanical locks formed in the flaps to form the bottom panel of the carton. Since the bottom panel must maintain its integrity throughout the use of the carton, it is essential that the locking system be capable of supporting the weight of the packaged articles, and remain engaged during shipping and handling of the constructed carton. 
     One approach to provide such a stable mechanical lock assembly utilizes primary and secondary locks. The primary locks connect the ends of the carton together via the flaps, while the secondary locks function to maintain the engaged flaps in place in order to provide a “backup” locking system to prevent the primary locks from separating. 
     A superior locking system that overcomes many of the deficiencies of prior art locks is disclosed in U.S. Pat. No. 5,443,203 to Sutherland, which describes a mechanical locking system that does not require secondary male locking tabs to extend beyond the end edges of the blank, but which system effectively locks the tabs in place and resists withdrawal of the tabs. Yet, neither this mechanical locking system, nor other prior art systems, incorporate the ability to adjust to the variation in size of the bottles contained by the carton. That is, prior art carton blanks are stamped for a particular sized bottle. Variations in bottle size or out of round bottles necessitate a new carton to accommodate the change. 
     It would be advantageous to provide a variable mechanical locking system that can adjust for bottle growth or out of round bottles. This type of assembly would allow a single carton to contain a range of different bottle sizes. The present invention and its preferred embodiments provide such variable locking, while they also provide a superior flap engagement assembly. 
     SUMMARY OF THE INVENTION 
     Briefly described, in a preferred form, the objects of this invention are achieved by providing both primary and secondary lock systems. The primary lock system allows for container growth or out of round containers in the carton. The primary lock system incorporates two primary locks of different sizes located in the carton&#39;s outer bottom panel flap so that at least one of these locks will engage with the female sloped lock ledge of the carton&#39;s inner bottom panel flap. Both of these primary locks will be engaged when the containers are of normal size. If the containers are oversized or out of round, then only the larger of the primary locks will be engaged. 
     The primary locks of this invention are secured in the engaged position by the provision of a secondary lock system that prevents the withdrawal of the primary male locks. A secondary male lock is located in the inner bottom panel flap and connected to the panel by a fold line spaced from the end edge of the flap. An intermediate fold line divides the secondary male lock into an outer portion that extends through a secondary female lock opening in the outer bottom panel flap when the carton is locked. The female lock opening has an edge of a retainer tab that assists in holding the secondary male lock in position. This retainer tab flap prevents the withdrawal of the secondary male lock, which maintains the primary lock system in locked condition. 
     Primary locking of the carton includes the engagement of at least one primary lock with the novel female sloped lock ledge that forms one end of the primary female lock tab aperture in the inner bottom panel flap. This configuration allows for product growth or out of round products contained in the carton. A carton for containing six (6) containers usually has three (3) sets of two (2) primary male locks, three (3) corresponding primary female lock tab apertures, three (3) secondary male locks and three (3) corresponding secondary female lock openings. 
     It is an object of the present invention to provide variable carton lock assemblies that are capable of a range of adjustment, yet throughout adjustment, the lock assemblies remain locked. These lock assemblies secure the inner and outer bottom panel flaps of the carton together without the use of glue and the like. 
     It is a further object of the present invention to provide at least one of the lock assemblies that is self adjusting to allow for container growth or out of round containers, and yet remain in the locked position at all times. 
     These and other objects, features, and advantages of the present invention will become more apparent upon reading the following specification in conjunction with the accompanying drawing figures. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a preferred carton in a set up condition and containing bottles, which carton incorporates the variable locking features of the present invention. 
     FIG. 2 is a plan view of a blank from which the carton of FIG. 1 is formed; 
     FIG. 3 is a plan view of the side panel and inner bottom panel flap of the blank of FIG. 2; 
     FIG. 4 is a perspective view of a secondary male lock and a primary female lock tab aperture of the present locking assembly according to a preferred embodiment; 
     FIG. 5 is a plan view of the side panel and outer bottom panel flap of the blank of FIG. 2; 
     FIG. 6 is a pictorial view of the bottom of a preferred carton, with the bottles removed for the purpose of clarity, demonstrating the first phase of the formation of the bottom panel; 
     FIG. 7 is a pictorial view similar to that of FIG. 6 but showing the bottom panel flaps at a next intermediate stage of bottom panel formation; 
     FIG. 8 is a schematic view of the overlapping relationship of the inner and outer bottom panel flaps when two primary locks engage the female sloped lock ledge of the present invention. 
     FIG. 9 is a schematic view of the overlapping relationship of the inner and outer bottom panel flaps when only one of two primary locks engages the female sloped lock ledge of the present invention. 
     FIG. 10 is a partial pictorial view illustrating a secondary male lock in position to be inserted into a secondary female lock opening; 
     FIG. 11 is an enlarged transverse sectional view of FIG. 10 just prior to secondary male lock insertion into secondary female lock ledge opening; 
     FIG. 12 is a partial pictorial view similar to that of FIG. 10, but illustrating the secondary male lock at a later intermediate position during formation of the bottom panel; 
     FIG. 13 is an enlarged transverse sectional view of FIG. 12; 
     FIG. 14 is a partial pictorial view similar to that of FIG. 10, but illustrating the secondary male lock in its fully inserted position; and 
     FIG. 15 is an enlarged transverse sectional view of FIG.  14 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The present invention is intended primarily for use with wrap-around cartons containing bottles of the types used to contain soft drinks, beer and the like. A typical example of such a bottle has a generally cylindrical body with an upper portion and a bottom, a tapering shoulder smoothly continuous with the upper portion of the body, and a neck formed on the shoulder having a smaller diameter than the body. This conventional bottle B also has a neck flange projecting outwardly from the neck, and a cap attached to the upper end of the neck flange. 
     A constructed wrap-around carton  10  is illustrated in FIG. 1 containing six beverage bottles B arranged in two rows of three each. The bottles B are packaged in the wrap-around carton  10  that is illustrated in blank form in FIG.  2 . The blank is formed from a foldable sheet material, such as paperboard. The carton  10  preferably is comprised of upper side panels  12 , lower side panels  14  and top panel  16 . Finger gripping apertures  22  and  24 , preferably formed by folding finger grip tabs  26  and  28 , are formed in the top panel  16  for the purpose of holding the carton  10 . Alternatively, finger gripping apertures  22  and  24  may be formed upon original die stamping of the carton  10 , wherein tabs  26  and  28  are removed at that time. 
     The carton  10  further comprises bottle neck openings  32  to permit the extension of a portion of both the neck of the bottle B and the bottle cap outside the body of the carton  10 . The carton  10  also includes heel restraining assemblies  34  adjacent the bottom panel, and the bottom panel is comprised of overlapping flaps  42  and  44 . 
     It will be understood by those in the art that the preferable carton  10  is symmetrical about a horizontal line of bisection, as viewed when FIG. 2 is rotated lengthwise. This symmetry aids in the efficient production of the present carton. The carton need not have such symmetry, although it is preferred. As shown, the blank is rectangular in shape and includes straight edges, which also makes for an efficient layout of the blanks in a web from which the blanks are cut. 
     Referring now to FIG. 2, the top panel  16  is foldably joined to upper side panels  12  by fold lines  52 . Fold lines  52  are interrupted by bottle neck openings  32 . Upper side panels  12  are in turn foldably joined to lower side panels  14  by fold lines  54 . Flaps  42 ,  44  are foldably joined to lower side panels  14  by fold lines  56 . Fold lines  56  are interrupted by the heel restraining assemblies  34 . 
     Referring specifically to FIGS.  2 - 4 , the inner bottom panel flap  42  includes secondary male locks  92 , one located opposite each heel restraining assembly  34 , and connected to the inner bottom panel flap  42  by fold line  94 . First and second tab cutouts  96 ,  98  are located to either side of the secondary male locks  92 . Upon lifting lock  92  about fold line  94 , cutouts  96 ,  98  merge into an integral primary female lock tab aperture  100 , shown in FIG.  4 . The outermost end of aperture  100  is formed by an offset lock ledge, or female sloped lock ledge,  102 . The slope of offset lock ledge  102  provides the present locking systems with a range of varying locking positions when ledge  102  is in engagement with first or second primary male locks of outer bottom panel flap  44 , described below. 
     As shown in FIG. 3, the main body of each secondary male lock  92  is formed by slits  104 ,  106  extending outwardly from the ends of the fold line  94 , and transverse slit  108 . Slit  108  forms the middle portion of offset lock ledge  102 . Slits  104 ,  106 , fold line  94  and offset lock ledge  102  bound aperture  100  when tab  92  is lifted, as illustrated in FIG.  4 . Secondary male lock  92  is divided into two portions by fold line  112 . The lock portion  114  of the secondary male lock  92  extends outwardly of the fold line  112  ends at slit  108  of offset lock ledge  102 . 
     As shown in FIGS. 2 and 5, the outer bottom panel flap  44  includes a locking panel section  60  connected to the main body of the flap  44  by a fold line  46 . Locking panel section  60  can be divided into primary lock panel sections  61  by slits  63 . Preferably, the number of primary lock panel sections  61  equals the number of heel restraining assemblies  34 , and each primary lock panel section  61  is of an equal size and shape. The slits  63  between the primary lock panel sections  61  permit small adjustments in the carton size. The bottle size may vary between primary lock panel sections  61  which enables each lock panel section to adjust to the size of the bottles immediately above the primary lock panel section  61 . Interrupting the fold line  46  opposite each heel restraining assembly  34  are spaced slits  62 , each slit  62  forming first and second primary locks  64 ,  66 . 
     Located in the locking panel section  60  opposite each set of first and second primary locks  64 ,  66  are slits  68 , each of which includes an outwardly extending accurate portion  72  forming a small retainer tab  74 . The slits  68  form secondary female lock openings which function in conjunction with the secondary male locks  92  as explained in more detail below. Fold lines  76  are outwardly spaced from the slits  68 , and the ends of the fold lines  76  and the slits  68  are connected by transverse slits  78 , which extend slightly beyond the slits  68 . This arrangement forms retaining flaps  82  adjacent the slits  68 . 
     The locking systems of the present invention as described include both a primary locking system and a secondary locking system. The primary locking system is the locking arrangement between the first and second primary locks  64 ,  66  of primary lock panel sections  61 , and the female sloped lock ledge  102  forming an end of primary female lock tab aperture  100 . The secondary locking system is the locking arrangement between the secondary female lock openings (slit  68 ), and the secondary male locks  92 . 
     The wrap-around carton  10  of FIG. 1 is formed by moving the top panel  16  of the blank so that a portion of the necks of a group of bottles B extend up through the bottle neck openings  32 . The blank is pulled tight about the bottles B and the bottom panel flaps  42 ,  44  are overlapped. The primary lock panel sections  61  of locking panel section  60  and the secondary male locks  92  of inner bottom panel flap  42  are then folded back as shown in FIG. 6 (which omits the bottles B for the purpose of clarity), after which the primary lock panel sections  61  are folded down into final position as shown in FIG.  7 . Either or both first and second primary locks  64 ,  66  are placed into primary female lock tab aperture  100  in proximity to offset lock ledge  102 . As primary lock panel sections  61  are folded down, one or both of the first and second primary locks  64 ,  66  engage the offset lock ledge  102 , and in their final position are located beneath the inner bottom panel flap  42  as viewed in FIGS. 6 and 7. 
     FIG. 8 illustrates both first and second primary locks  64 ,  66  tucked under inner bottom flap  42 . This would be possible when, for example, bottles B are neither too large nor out of round. If bottles B necessitate that the bottom panel of the carton  10  be wider to contain bottles B, flaps  42 ,  44  can move in opposite directions, as referenced by arrows A, thus widening the bottom panel. Yet, the primary locking system of the present invention will remain locked even if lock  66  disengages offset lock ledge  102 , as shown in FIG. 9, as lock  64  remains tucked under offset lock ledge  102  because lock  64  extends further than lock  66 . 
     It will be understood by those in the art that while slit  62  is shown in FIG. 5 forming two locking tabs, slit  62  can form more than two locking tabs, each providing another range of locking positions. 
     FIGS. 8 and 9 also illustrate the novel aspect of providing the carton  10  with a offset lock ledge  102 , thus enabling the bottom panel to vary in a range of widths and still remain locked. Further, this variability does not require a new blank design each time the bottle size changes within the range of bottom panel widths provided by the offset lock ledge  102 . Additionally, the variability of bottom panel sizes does not interfere with the locking relationship of bottom flaps  42 ,  44 . 
     Since offset lock ledge  102  is sloped, and since the size of the bottom panel is defined by the engagement between locks  64 ,  66  and offset lock ledge  102 , it is apparent that the size of the bottom panel will vary according to the location of engagement of locks  64 ,  66  along the length of offset lock ledge  102 . FIGS. 3 and 8 illustrate a representative embodiment of offset lock ledge  102  as related to the end of inner bottom panel  42  opposite fold line  56 . The distance between offset lock ledge  102  and the end of panel  42  varies between the distances X and Y. Although offset lock ledge  102  is depicted with a constant slope, it will be understood that this need not be the case. Generally, the bottom panel of carton  10  can vary in size by the approximate distance of Y-X. Depending on where one or both of the first and second primary locks  64 ,  66  engage offset, or sloped, lock ledge  102  along its length, the bottom panel can adjust between a range that is determined mainly by the difference in distances X and Y, being the ends of the offset lock ledge  102 . 
     Further, the carton  10  is self-adjusting, as locking tabs  64 ,  66  will shift along the length of offset lock ledge  102  in the direction of arrows B or C when the carton  10  with bottles B is raised by top panel  16 . 
     Thus, the present invention can accommodate a range of sizes of bottles B, without the need to modify the blank of the carton  10 . The varying lengths of locks  64 ,  66 , as well as the sloping offset lock ledge  102 , provide the range of bottom panel sizes. 
     The secondary locking system is shown in FIGS.  10 - 15 . As illustrated in FIGS. 10 and 11, the secondary male locks  92  are pivoted forward about the fold lines  94  and their outer portion  114  is folded about the fold line  112  to position the end of the outer portion  114  over the retaining flaps  82  of the secondary female lock openings adjacent the retainer tabs  74 . The secondary male locks  92  are then pushed toward the interior of the carton  10 , causing the flaps  82  to slightly pivot about their fold lines  76  to permit the angular entry of the outer portions  114  into the space created between the retaining flaps  82  and the edge formed by slits  68 . The transverse slits  78  allow adjacent portions of the locking panel section  60  to yield slightly to permit continued downward passage of the outer portion  114  of secondary male locks  92 . The relationship of the various locking elements to each other during this intermediate phase of the locking process is illustrated in FIGS. 12 and 13. 
     Continued movement of the secondary male locks  92  results in the outer portions  114  being fully inserted into the secondary lock openings as shown in FIGS. 14 and 15. During movement of the outer portions  114  of the secondary male locks  92  through the secondary lock openings, the angle between the outer portions  114  and the bottom panel flaps  42 ,  44  progresses toward a right angle. This can be seen by comparing FIGS. 11,  13  and  15 . The contact between the retaining flaps  82  and the outer portions  114  continually biases the outer portions  114  during their movement through the secondary locking openings toward the edges formed by the slits  68 . As a result, the outer portions  114  contact and slide past the retaining tabs  74 . When relative movement between the secondary locking tab portions  114  and the retainer tabs  74  brings the fold line  112  in proximity to tabs  74 , the secondary locking of the locking system of the present invention is established. At the same time, the secondary male locks  92  can slide along the length of slit  68 , in step with any sliding of locks  64 ,  66  along offset lock ledge  102 . The fold line  112  can incorporate a knife cut  113 , shown in FIG. 3, which would enable tab  74  to insert through cut  113 . 
     It will be understood that flap  42  need not incorporate apertures  100 , but only needs offset lock ledge  102  (being a slit cut in panel  42 ), to lock the primary locking subsystem of the carton  10 . 
     While the locking system of the present invention has been described, below is the preferred embodiment of further elements of the carton  10 . 
     The heels of the contained bottles B are restrained from movement by the provision of heel restraining assemblies  34  of the carton  10 , or any other suitable means for restraining the heels of the bottles from falling out of the open ends of the carton  10 . It is particularly important to restrain the outside bottles from movement as they in turn will restrain the movement of the inner bottles in the carton  10 . A preferred type of heel restraining assembly  34  is illustrated in FIG.  3 . Heel doors  122  are provided in the bottom of each lower side panel  14  and extend into the corresponding inner and outer bottom panel flaps  42 ,  44  through fold lines  56 . These doors open inwardly during the erection of the carton  10  from a cut line  124  between each set of heel doors. These doors are hinged to the panels and flaps by fold lines  126 . These fold lines  126  permit the heel doors  122  of the carton  10  to be swung inwardly during erection. This permits each bottle B to be nested between a set of adjacent heel doors  122  of each heel restraining assembly  34 . This facilitates holding each bottle B in proper position, as illustrated in FIG.  1 . More importantly, these doors tend to restrain tearing around the heel apertures that are formed by these doors. Without these doors  122  there would only be cuts that could easily be torn. Further, these doors provide a flexible buffer against which the heel of the bottle can abut without tearing the carton panel surrounding the heel restraining aperture. 
     Accurate cut lines  130  may be formed at the top of each set of doors to permit the carton to be stretched more tightly over the heels of the bottles. Perpendicular cut lines  132  may also be provided to reduce the stress on the paperboard around the heel of the bottle. The door opening effect allows a relatively large portion of the heel of the bottles to be inserted into the aperture formed by the doors&#39; opening, thereby enabling a relatively strong pack to tighten while minimizing the risk of tearing. As it is important to tighten the carton  10  tightly around the bottles, tightening apertures  140  are provided as extensions into the bottom flaps of the apertures formed by heel doors  122 . The tightening apertures  140  allow mechanical tightening fingers to enter and tighten the carton during erection. 
     While the invention has been disclosed in its preferred forms, it will be apparent to those skilled in the art that many modifications, additions, and deletions can be made therein without departing from the spirit and scope of the invention and its equivalents as set forth in the following claims.