Abstract:
A container for carrying produce having dove tail locks is created from a container blank having nonsymmetrical, offset dove tail locks on the edges of the blank. When the blank is on a larger paperboard substrate having multiple blanks, the dove tail locks of a blank border the dove tail locks of an adjacent blank in a configuration that eliminates pinch points. The elimination of pinch points is achieved by having dove tail locks wherein the sides of the dove tail lock diverge from each other at different angles and for different horizontal vectors.

Description:
RELATED APPLICATION  
       [0001]    This application claims priority from U.S. Provisional Application Serial No. 60/394,754, filed Mar. 14, 2002. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    The present invention relates to a paper or paperboard container having dove tail locks, wherein the paperboard container is created form a blank having offset, non-symmetrical dove tail locks. Further, the present invention relates to a paperboard substrate having multiple contiguous paperboard blanks, wherein the dove tail locks of one blank border the dove tail locks of an adjacent blank in a configuration that eliminates angles of less than 90 degrees.  
         BACKGROUND OF THE INVENTION  
         [0003]    Corrugated paperboard is typically used in many different applications, for example, to form containers, boxes, cartons, or dividers for holding, storing or shipping various items such as agricultural produce.  
           [0004]    Typically, such containers have a bottom and four side walls, and are formed from a blank scored with score lines or cut lines. The blanks are most often formed by automated machines in a continuous in-line process involving scoring and cutting a large substrate of paperboard into blanks of a desired configuration. During scoring and cutting, multiple, virtually identical container blanks are contiguously formed on a large, single substrate of paperboard. The automated machines separate the substrate into individual blanks by severing common intermediate cut lines with cutting knives. The resultant individual blanks are then folded along the score lines or cut lines to form functional containers. The blanks may be folded into a container manually or by an automated machine.  
           [0005]    An individual container blank, on its own, often contains knife recesses or other cut out formations along the outer edges of the blank. However, during severance from a large paperboard substrate, the outer edge of the blank borders a virtually identical blank along an intermediate common cut line. In these circumstances, the die cut recesses or other cut out formations touch each other across the intermediate common cut line, essentially forming a combined cut out shape. For example, a blank may include dove tail locks, which are recesses having a flat base and two angled side walls that extend from the base to an open mouth top at the edge of the side wall, and may further have identical recesses on an opposing side edge. When this happens on contiguous blanks on a larger paperboard substrate, the open mouth of the dove tail lock on one blank will border the open mouth of a dovetail lock on an adjacent blank. As a result, the two bordering locks form a single, larger cut out shape that traverses the intermediate common cut line. When the blanks are fully separated across the intermediate common cut line, the individual blanks once again have separate dove tail locks.  
           [0006]    However, to account for the thickness of the blank&#39;s panels when they are folded over one another during the formation of the container, the recesses cut out of one end of a blank are sometimes offset from the recesses on the opposite end of the blank by moving one recess a small lateral distance as opposed to the other. For example, the dove tail lock on one end of a blank can be laterally spaced ⅛ inch from a dove tail lock on the opposing edge. Stemming from that offset, when the blanks are arranged adjacently on a single substrate, the dove tail locks on one blank are offset from the bordering dove tail lock on the adjacent blank. That is to say, the open mouth top of the dove tail lock on one blank does not perfectly align with the open mouth top of the adjacent dove tail lock. This results in a combined cut out shape having sharp angles of less than 90°, called pinch points, which are undesirable because they are difficult to properly cut, leaving frayed edges and causing extra wear and tear on the cutting knife.  
           [0007]    Therefore, it is an object of this invention to provide a paperboard blank that eliminates pinch points when aligned with an adjacent, identical blank on the same paperboard substrate.  
         SUMMARY OF THE INVENTION  
         [0008]    The present invention comprises a paperboard container formed from a paperboard blank, wherein the blank contains non-symmetrical offset dove tail locks, which eliminate pinch points and increase the ease of separating the blank from a larger paperboard substrate.  
           [0009]    The container is a corrugated box of a type often used for transporting food items, with a bottom side, two side walls, two end walls and a removable lid. The container further contains dove tail locks on the end walls to facilitate the locking of the container in an upright, erect position. A dove tail lock, as stated above, is a cut recess wherein the shape of the recess resembles a tail of a bird, that is to say, it is a recess with a base line, two angled slope lines moving in diverging or converging paths, and an open mouth top.  
           [0010]    When the container is in its blank form, the dove tail locks are cut into opposing sides of the container blank. Each dove tail lock is offset from its opposing dove tail lock by a small lateral distance to account for the thickness of the paperboard during folding. However, the offset opposing dove tail locks are non-symmetrical, such that each slope line of the dove tail locks extend at different horizontal distances (vectors). The different vectors result in each slope line extending a different horizontal distance during its path from the base line to the open top than its corresponding, opposing slope line. The difference in the horizontal distances eliminates pinch points by aligning the open mouth tops of two adjacent dove tail locks together.  
           [0011]    One embodiment of the invention includes dove tail locks having a base line, two slope lines and an open mouth top, wherein the slope lines of the locks are single lines that angle divergently away from each other at different angles relative to the base line. Each slope line of the dove tail locks crosses different horizontal vectors, creating a non-symmetrical lock that eliminates pinch points when multiple blanks are contiguously scored and cut on a single paperboard substrate.  
           [0012]    Further embodiments include dove tail locks wherein the slope lines of the locks are segmented. In these embodiments, one segment extends perpendicular to the base and in parallel to a corresponding segment on the opposing side of the lock. The parallel segments combine with second segments that extend divergently away from each other at different angles relative to the base line and the first segments. This embodiment also results in each slope line of the dove tail lock traveling different horizontal vectors, eliminating pinch points when the blank borders an adjacent blank on a paperboard substrate.  
           [0013]    Other objects, embodiments, features and advantages of the present invention will be apparent when the description of a preferred embodiment of the invention is considered in conjunction with the annexed drawings, which should be construed in an illustrative and not limiting sense. 
       
    
    
     BRIEF DESCRIPTION OF THE FIGURES/DRAWINGS  
       [0014]    [0014]FIG. 1 is a plan view of a prior art paperboard blank.  
         [0015]    [0015]FIG. 2 is a partial view of two adjacent prior art blanks on a paperboard substrate.  
         [0016]    [0016]FIG. 3 is a plan view of a paperboard blank.  
         [0017]    [0017]FIG. 4 is a plan view of an alternate embodiment of a paperboard blank.  
         [0018]    [0018]FIG. 5 is a partial view of two end panels of FIG. 3 and their respective dove tail locks overlapping.  
         [0019]    [0019]FIG. 6 is a partial view of two adjacent blanks on a paperboard substrate.  
         [0020]    [0020]FIGS. 7 a - 7   b  are perspective views of the container blanks of FIGS. 3 and 4 folded and erected into a container. 
     
    
     DETAILED DESCRIPTION  
       [0021]    [0021]FIGS. 1 and 2 show prior art blank  10  scored and cut from a larger corrugated substrate, wherein the corrugated substrate contains multiple substrates in a contiguous arrangement. Blank  10  is a poultry container with a base panel  28 , end panels  24  foldably attached to base panel  28  along opposite, parallel fold lines  32 , and side panels  20  and  40 , foldably attached to base panel  28  along opposite, parallel fold lines  30 . Each side panel has two end flaps,  22  or  26 , foldably attached to the side panel along opposite fold lines  36  and  38 .  
         [0022]    Each end flap has at least one dove tail lock  2 . The dove tail locks are die cut recesses, cut from the outer edge of the side panels. Referring to FIG. 2, die cut recesses are generally trapezoidal in shape, with a base line  34 , two slope lines  42  and  44  diagonally diverging at identical vectors and angles relative to the base line, and an open mouth top. Slope lines  42  and  44  are segmented, wherein the first segments extend perpendicular from the base line and parallel to each other, and the second segment diverge at identical vectors X relative to the base line. In other prior art embodiments, slope lines  42  and  44  may be a single line with a vector X, without any segmentation.  
         [0023]    To erect the container, end panels  20  and  40  of FIG. 1 are first folded about a horizontal axis  30 , upwards about 90°, out of the plane of the base panel. Second, end flaps  22  and  26  are folded along vertical fold lines  36  and  38  toward the base panel about 90°, wherein they overlap each other in a face-to-face arrangement, such that their respective dove tail locks similarly overlap one another. Third, end panels  24  are folded upwards, out of the plane of the base panel. End panel  24  overlaps end flaps  22  and  26  in a face-to-face-to-face arrangement, resulting in a three-ply end wall that is triple the thickness of the blank.  
         [0024]    To overlap properly, however, the thickness of the paperboard must be accounted for. Failing to do so would result in end panel  22  and end panel  26  obstructing each other by attempting to fold into the same location. Avoiding this requires the length of end panel  22  to be slightly different than the length of end panel  26 . As a result of this length difference, each end panel naturally folds next each other without interference.  
         [0025]    Corresponding with the length differences of the end panels, the dove tail locks on end panels  22  are offset a small lateral distance as compared to the dove tail locks on end panels  26 . This offset accounts for the thickness of the paperboard and allows the dove tail locks to properly align with each other when overlapped on the end wall.  
         [0026]    Prior art blank  10  is generally scored and cut on a large paperboard substrate with multiple other blanks in a continuous in-line process. FIG. 2 shows the prior art with a partial view of two adjacent paperboard blanks,  10  and  10 A, particularly their end flaps  22  and  26 . The open top mouth of the dove tail locks on blank  10  are adjacent to the open top mouth of dove tail locks on blank  10 A. Due to slightly different lengths of the end flap and corresponding offset of the dove tail locks, the open ended sides of the dove tail locks are offset a small distance X, in the present example about ⅛ inch. The result of this offset are small cut-out shapes  46  that have angles of less than 90°, called pinch points, which are undesirable because they are difficult to properly cut when the adjacent blanks are severed along intermediate common cut line  4 , creating frayed edges and causing extra wear and tear on the cutting knife.  
         [0027]    One embodiment of the present invention is shown in FIG. 3. Blank  10 ′ is a blank scored and cut from a larger corrugated substrate, wherein the substrate contains multiple container blanks adjacent to one another. Blank  10 ′ has a base panel  28 , end panels  24  foldably attached to base panel  28  along opposite, parallel fold lines  32 , and side panels  20  and  40  foldably attached to base panel  28  along opposite, parallel fold lines  30 . Side panels  20  and  40  each have two side flaps foldably attached to the side panel along opposite fold lines  36  and  38 . Side flaps  22  foldably attach along fold line  36 , and side flaps  26  foldably attach along fold line  38 . The length of side flaps  22  and  26  are slightly different to account for the thickness of the flaps when they are folded over one another in a face-to-face arrangement when the container is erected. For example, in the current example, side flap  22  is ⅛ of an inch longer than side flap  26 .  
         [0028]    Each side flap has at least one dove tail lock  2 . The dove tail locks are die cut recesses, cut out from the outer edge of the side panels. The die cut recesses are generally trapezoidal in shape, with a base line  34 , two opposing slope lines  42  and  44  diagonally diverging at different angles relative to the base line, and an open mouth top. The different angles of the opposing slope lines result in different horizontal vectors of the slope lines, i.e., the slope lines travel different horizontal distances as they extend from the base line to the open top mouth. For example, in the present example, slope line  42  has a horizontal vector of ¼ inch, while slope line  44  has a horizontal vector of ⅛ inch. In general, the difference of the horizontal vectors of the two slope lines is equivalent to the difference in length of end flap  22  and end flap  26 .  
         [0029]    In the embodiment shown in FIGS.  3 - 6 , each slope line is made up of two segments. The first segment of each slop line extends perpendicularly from base line  34 . The second segment of each slope line extends at an angle from the end of the first segments to the top edge of the end panel. The second segments diverge at different angles relative to the base line and the first segment, resulting in a horizontal vector of the second segment of slope line  42  being different than the second segment of slope line  44 . In the present example, the second segment of slope line  42  has a horizontal vector of ¼ inch, whereas the second segment of slope line  44  has a horizontal vector of ⅛ inch.  
         [0030]    To erect the container of FIG. 3, end panels  20  and  40  are first folded about a horizontal axis  30 , upwards 90°, out of the plane of the base panel. Second, end flaps  22  and  26  are folded along vertical axis  36  and  38  toward the base panel about 90°, overlapping each other. As shown in FIG. 5 , when end panels  22  and  26  overlap one another, the dove tail locks of the end panels similarly overlap one another, creating a thicker combined recess in the end wall. To align evenly, the slope line with a horizontal vector X on panel  22  matches with the corresponding slope line of the same vector on panel  26 . Likewise, the slope line with a horizontal vector Y on panel  22  aligns with the corresponding slope line of the horizontal vector on panel  26 . The resultant combined recess is asymmetrical yet aligned without excess paperboard of one panel protruding into the recess of an adjacent panel.  
         [0031]    Third, end panels  24  are folded about horizontal axis  32  upwards 90° out of the plane. The end flaps  22  and  26  overlap each other and end panel  24  in a face-to-face-to-face arrangement, resulting in a three-ply end wall that is triple the thickness of the blank. The locking flap  60  is then pulled down through the dove tail locks of flaps  22  and  26 , locking the container in an erect position, shown in FIG. 7A.  
         [0032]    An alternate embodiment is shown in FIG. 4. Middle panels  50  and  52  are located between each side panel and their respective side flaps. Flaps  22  and  26  foldably attach to middle panels  50  and  52  along score lines  54  and  56 . To account for the thickness of the paperboard during folding, the length of middle panel  50  is slightly different than the length of middle panel  52  (about ⅛ of an inch in the present example). As a result, opposing end panels  22  and  26  and their respective dove tail locks are laterally offset from each other. However, slope lines  42  and  44  of dove tail locks  2  extend different horizontal distances, accounting for the offset, eliminating pinch points when cutting on a larger paperboard substrate. When the blank shown in FIG. 4 is erected, the result is the container shown in FIG. 7B.  
         [0033]    When blank  10 ′ of FIG. 3 or  4  is scored and cut on a paperboard substrate in a continuous in-line process, multiple blanks are scored and cut on the same substrate, wherein the intermediate cut line is cut simultaneously with the cutting of the dove tail locks. FIG. 6 shows a partial view of two adjacent paperboard blanks,  10 ′ and  10 A′, particularly their end flaps  22  and  26 , post cutting. The dove tail locks  2  on blank  10 ′ lie adjacent to dove tail locks  2  on blank  10 A′. Due to slightly different lengths of the side flaps, base lines  34  of the dove tail locks are laterally offset. However, the offset is accounted for by the horizontal vector Y of slope line  42 , which, unlike the prior art, is different than the horizontal vector X of slope line  44 . Ideally, the horizontal vector Y of slope line  42  is altered so that the top of slope line  42  abuts the top of slope line  44  on the adjacent blank. Thus, the slope lines  42  and  44  will touch at the same point on intermediate common cut line  4 . As a result, corners  46  do not contain pinch points, i.e. angles of less than 90°, resulting in less wear and tear on the cutting knife during cutting of dove tail lock  2  and intermediate cut line  4 , and fewer frayed edges on the blanks after the cutting.  
         [0034]    In alternate embodiments, slope lines  42  and  44  may have different geometric arrangements, for example, containing only a angled segment without a first segment that extends perpendicular to the base line. However, in these embodiments, the integrity of the horizontal vector of sides  42  and  44  are maintained. That is to say, side  42  would still have the same horizontal vector Y, whereas slope line  44  would have an horizontal vector X, different from that of Y, resulting in the elimination of corners with angles of less than 90° when adjacent container blanks touch on a larger paperboard substrate.  
         [0035]    Although the invention has been described with reference to preferred embodiments, it will be appreciated by one of ordinary skill in the art that numerous modifications are possible in light of the above disclosure. For example, the base line of the dove tail locks may be cut non-parallel to the edge of the blank or intermediate cut line. Further, the slope lines of the dove tail locks may be further segmented. All such variations and modifications are intended to be within the scope and spirit of the invention as defined in the claims appended hereto.