Corrugated container

A self-squaring corrugated container employs alignment markings on and adjacent to the manufacturing joint to allow quick visual inspection of placement and orientation of the manufacturing joint, and employs interlocking contoured peripheral edges on the major bottom flaps to allow consistent, quick, and easy formation of a container which is square, non-skewed to within small, strict tolerances. Both the alignment markings and contoured bottom flaps are die cut into the carton blank to insure uniform container alignment. Additional container features include employment of a hinged, partially detached top flap to accommodate use of the container to packaged bottles. Method steps are provided for forming the self-squaring container using the innovative features.

BACKGROUND OF THE INVENTION

In product packaging using corrugated containers, formation of containers having flaps which are correctly aligned and non-skewed is required to meet manufacturer specifications and to provide packaging which is secure, protective, and of pleasing appearance. Certain applications require containers which are consistently and uniformly square and non-skewed. One such application is the use of corrugated containers to package bottled photographic processing chemicals, where the both the container and its bottled chemicals are inserted into a dedicated opening within a photographic processing machine. In this application, the container must be square and non-skewed within extremely tight tolerances. If the container is malformed, that is, out of square and or skewed out side of the required tolerances, it will not fit into the dedicated opening. Containers which are formed nearly within the required tolerances may possibly be inserted within the dedicated opening, but the chemicals may not be correctly aligned within the machine, causing machine malfunction.

Conventional rectangular corrugated containers are typically manufactured from a single piece of corrugated board, corrugated board, or similar material. They are die cut into a blank having a predetermined pattern and provided with indented fold lines to facilitate folding into a rectangular container. The container manufacturer usually folds the corrugated board blank along two of the fold lines so as to overlap and seal the leading and trailing lateral edges, forming a manufacturing joint. This process results in a flattened, or knock-down, product. A random sample of knocked-down containers are inspected by manual measurement using a ruler to insure that the product is formed to packager specifications and within required tolerances. Once the measurements are complete, the measured results are compared to the specifications. Containers measuring within the specifications are retained, and all remaining containers are discarded. Typically, product is shipped to the packaging facility in this compact, knocked-down form.

In instances where consistent and uniformly square and non-skewed containers are required, samples of the knocked-down corrugated board product are again inspected upon arrival at the packaging facility, and additional samples are inspected prior to use on forming-and-filling assembly lines. Upon passing inspections, the knocked-down corrugated board product is erected into a hollow tubular shape, filled, and then the bottom and top flaps are folded and sealed.

In this manufacturing process, there are two stages at which the quality of square and skew of the container are determined. The first stage is the folding of the corrugated board blank to form the manufacturing joint. If the blank is over folded, under folded, or folded so that the edges are not correctly aligned, the resulting container will not be square or will be skewed, or a combination of both. The second stage is when the bottom and top flaps of the tubular, filled container are folded and sealed. If these flaps are not correctly aligned with each other and with the side walls of the container, the container will not be square or will be skewed, or a combination of both. Typically, manufacturers of corrugated containers have difficulty providing containers which are properly aligned and non-skewed, and have no simple way to see that each and every container meets specifications.

Improvements in container design which allow containers to be more easily formed having square and aligned components would greatly improve packaging efficiency and quality. Specifically, a container design which addresses the issue of improvements in consistency in formation of both the manufacturing joint and the top and bottom flap fold are key to creating a consistently and uniformly square and non-skewed corrugated container.

SUMMARY OF THE INVENTION

An innovative self-squaring corrugated container is disclosed herein which employs alignment markings on and adjacent to the manufacturing joint to allow quick visual inspection of placement and orientation of the manufacturing joint, thus eliminating the need for manual inspection of knocked down containers using rulers or other external measurement tools and which would allow every person handling the container, from line operator to quality control inspector, to visually check that containers meet manufacturing specifications. The container further employs interlocking contoured peripheral edges on the major bottom flaps to allow consistent, quick, and easy formation of a container which is square and non-skewed to within small, strict tolerances. As the container is formed, the interlocking finger-like projections of the respective bottom flaps engage each other and automatically squarely align and lock the flaps in such a way as to prevent relative motion between the bottom flaps, preventing the squarely formed container from skewing. Both the alignment markings and contoured bottom flaps are die cut into the carton blank to insure uniform container alignment.

Additional container features include employment of a hinged, partially detached top flap to accommodate use of the container to packaged bottles.

Method steps are provided for forming the self-squaring container using the innovative features.

DETAILED DESCRIPTION

To accommodate the use of a consistently square and non-skewed container10to package bottled photographic processing chemicals, where container10and the enclosed bottled photographic chemicals are inserted as a unit into a photographic processing machine, container10is provided with several innovative design features. In this application, the bottles5are provided with a necked portion7which receives a cap or bottle closure6, where cap6is much larger in diameter than neck7. Neck7and cap6extend above the top edge of container10when container10is completely folded (FIG. 1).

Improvements in container design, which are not limited to this specific application and may be applied generally to container manufacturing, include use of alignment markings and interlocking contoured peripheral edges on bottom flaps to allow consistent, quick, and easy formation of a container which is square, non-skewed to within small, strict tolerances. Improvements in container design, specific to the use of a consistently square and non-skewed carton to package bottled photographic processing chemicals for use in photographic processing machines, and which also has general applications, consist of the following: Rear side top flap40is detached from rear side wall24except at hinge65, rear side top flap40is provided with semicircular openings92in its peripheral edge to receive and surround the necks7of bottles5, and front side top flap42is provided with circular openings90to allow the caps6of bottles5to pass therethrough.

Referring now to the drawings, and initially toFIGS. 1 and 5, the inventive container10is formed by die cutting blank20from a sheet of corrugated board stock. This corrugated board stock may be paper board, or plastic board, and may be of single- or multiple-ply. The preferred material is a single-ply corrugated board of 3.1 mm (0.122 inch) thickness. However, it is well within the scope of this invention to use corrugated board of approximately two or three times this thickness. It is also well within the scope of this invention to use corrugated board which is as thin as 0.47 mm ( 1/64 inch) thickness.

Blank20has a predetermined, generally rectangular pattern and is provided with plural indented longitudinal and transverse fold lines to facilitate folding into a container. The indented longitudinal fold lines extend parallel to the longitudinal axis of container10, and the indented transverse fold lines extend perpendicularly to the indented longitudinal fold lines. Each blank20is provided with a first longitudinal fold line70which separates the first end wall22from the rear side wall24, a second longitudinal fold line72which separates the rear side wall24from the second end wall26, a third longitudinal fold line74which separates the second end wall26from the front side wall28, and a fourth longitudinal fold line76which separates the front side wall28from the end wall flange38.

Each blank20is further provided with an upper transverse fold line60and a lower transverse fold line62. Upper transverse fold line60defines the upper edge of container10and separates the rear side top flap40from the rear side wall24, and separates the front side top flap42from the front side wall28. The lower transverse fold line62defines the lower edge of the container and hingedly separates the rear side bottom flap32from the rear side wall24, hingedly separates the front side bottom flap36from the front side wall28, hingedly separates the first end bottom flap30from the first end wall22, and hingedly separates the second end bottom flap34from the second end wall26.

Blank20is provided with a first face12which corresponds to the exterior surface of the container, and a second face14which is opposed to the first face and which corresponds to the interior surface of the container. The respective first12and second faces14are spaced apart from each a distance which corresponds to the thickness of the corrugated board sheet.

Container10is provided by the manufacturer in a knocked-down, or flattened, tubular configuration (FIG. 12). Blank20is formed into this tubular configuration as follows: Blank20is folded along first longitudinal fold line70so that second face14of first end wall22overlies and confronts a portion of second face14of rear side wall24adjacent first longitudinal fold line70. Blank20is then folded along third longitudinal fold line74so that second face14of front side wall28overlies and confronts second face14of second end wall26and a second portion of rear side wall24, and so that second face14of end wall flange38overlies first face12of first end wall22. Second face14of end wall flange38is secured to the first face of the first end wall. Securement is accomplished by any conventional means, preferably by application of glue between end wall flange38and first end wall22. This securement of opposed lateral ends of blank20results in what is known as manufacturing joint25.

Alignment markings are die cut into blank20at strategic locations so as to allow instant visual determination of whether a knocked-down container has a properly aligned manufacturing joint. Four sets80,82,84,86of alignment markings are provided on blank20in the region of manufacturing joint25.

The first set80of alignment markings is located on first end wall22adjacent to but spaced apart from its top edge, or upper transverse fold line60. The second set82of alignment markings is located on first end wall22adjacent to but spaced apart from its bottom edge, or lower transverse fold line62. First set80and second set82are identical and are longitudinally aligned on first end wall22. Each respective first set80and second set82consists of two parallel cut lines which are aligned with the longitudinal axis of container10. The two lines are adjacent to each other and spaced apart a first distance.

The first set80and second set82of alignment markings are located and oriented on blank20so that when manufacturing joint25is correctly formed, the longitudinally aligned peripheral edge54of end wall flange38resides between the two lines of both first set80and second set82(FIG. 13). Thus, the markings of first set80and second set82provide a measure of transverse tolerance for placement of manufacturing joint25, as well as defining a range of allowable positions for joint placement in the transverse direction. The first distance, or relative spacing of the two markings, is determined by the allowable transverse error in placement of end wall flange38on first end wall22. In the preferred embodiment, this first distance is 5 mm. However, the first distance is dependent on the specific requirements of a given application, and thus may be greater than 5 mm in applications which container shape is less critical, and may be less than 5 mm in applications in which container shape is more critical.

FIGS. 14–16disclose a second embodiment180,184of the first set80and the second set84of alignment markings. In this second embodiment, the pair of parallel, longitudinally aligned cut lines is replaced with a rectangular shaped through cut hole. The rectangular hole is oriented on first end wall22such that the longitudinal axis of the rectangle is aligned with the longitudinal axis of container10. The transverse dimension of the rectangular hole is equal to the first distance, that is, it is determined by the allowable transverse error in placement of end wall flange38on first end wall22. Use of a through cut rectangular hole provides improved visualization of the markings, and their positional relationship to the manufacturing joint25.

The third set84of alignment markings is centered on first end wall22such that it lies midway between the upper and lower transverse fold lines60,62, and such that it lies midway between first longitudinal fold line70and the longitudinally aligned peripheral edge52of first end wall22. Third set84consists of three transversely aligned parallel lines: An upper marking, a center marking, and a lower marking. The upper marking and lower marking are each spaced apart a second distance from the center marking. The center marking is slightly longer than the upper and lower markings to improve visual differentiation between the three markings.

The fourth set86of alignment markings is located on end wall flange38such that it coincides with and extends inward from the longitudinally aligned peripheral edge54of end wall flange38, and is located midway between the upper and lower transverse fold lines60,62. Fourth set86also consists of three transversely aligned parallel lines comprising three markings, the three markings comprising an upper marking, a center marking, and a lower marking. The upper marking and lower marking are each spaced apart a second distance from the center marking. The center marking is slightly longer than the upper and lower markings to improve visual differentiation between the three markings.

The third84and fourth86sets of alignment markings are located and oriented on blank20so that when manufacturing joint25is correctly formed, the three markings of third set84are transversely aligned with the three markings of fourth set86. Specifically, the center line of third set84must lie between the upper and lower markings of fourth set86, and the center line of fourth set86must lie between the upper and lower markings of third set84(FIGS. 13–15). Thus, the markings of third set84and fourth set86provide a measure of longitudinal tolerance for placement of manufacturing joint25, as well as defining a range of allowable positions for joint placement in the longitudinal direction. The second distance, or relative spacing of the three markings, is determined by the allowable longitudinal error in placement of end wall flange38on first end wall22. In the preferred embodiment, this second distance is 3 mm. However, the second distance is dependent on the specific requirements of a given application, and thus may be greater in applications which container shape is less critical, and may be less in applications in which container shape is more critical.

Use of differing styles of alignment markings at different locations about manufacturing joint25is directly related to the criticality of the alignment at that location. Specifically, the three transversely aligned parallel lines of the third84and fourth86alignment sets provide a more fine gauge than the two longitudinally aligned parallel lines of the first82and second84alignment sets. However, it is within the scope of this invention to substitute a set of two transversely aligned parallel lines for the three-line embodiment of the third84and fourth86alignment sets, so that all four alignment sets80,82,84,86are identical. It is also within the scope of the invention to use the three-line paradigm for all four alignment sets.

In the preferred embodiment, the cut lines of each respective set of alignment markings are die cut completely through blank20such that both first face12and second face14are marked. By die cutting the markings into blank20concurrent with formation of blank20, the markings are inherently properly aligned with the longitudinal and transverse axes of blank20. Alignment errors which would be introduced in a two-step marking process, such as in the case of stamping out blank20and then imprinting alignment markings thereon, are avoided in this preferred embodiment. Die cutting the alignment markings completely through blank20also allows inspection of the carton from either the inside or the outside. However, it is well within the scope of this invention to die cut the alignment markings so that the cut line extends only partially through the thickness of the blank, as may be more practical when the blank is formed of very thick stock.

Improper alignment of manufacturing joint25is immediately determined by visual inspection. If the longitudinally aligned peripheral edge54of end wall flange38does not reside between the two lines of either first set80and/or second set82(FIGS. 15 and 16), the resulting container10will be non square, skewed, or both. If the three markings of third set84are not transversely aligned, as described above, with the three markings of fourth set86, but instead are longitudinally offset (FIG. 16), the resulting container10will be non square, skewed, or both. In any case, containers which, upon a simple visual inspection, do not have a properly located and aligned manufacturing joint can be discarded.

Once the knocked-down container is correctly formed so that the manufacturing joint25is properly located and aligned, it can be erected, or opened into a tubular form (FIG. 6) and filled. In order to ensure that the erected container is square and non-skewed, inventive bottom flaps32,36having squaring means are provided.

Front side bottom flap36is defined by lower transverse fold line62which separates it from front side wall28, and a free peripheral edge58which is opposed to lower transverse fold line62and separated from it by the body of the front side bottom flap36. Rear side bottom flap32is defined by lower transverse fold line62which separates it from rear side wall24, and a free peripheral edge56which is opposed to lower transverse fold line62and separated from it by the body of the rear side bottom flap32. Free peripheral edge58of the front side bottom flap36is provided with a thickness and a curvilinear contour. Free peripheral edge56of rear side bottom flap32is provided with a thickness and a curvilinear contour which is identical to the curvilinear contour of free peripheral edge58of front side bottom flap36, except that the curvilinear contour of free peripheral edge56of rear side bottom flap32is the negative of the curvilinear contour of free peripheral edge58of front side bottom flap36. That is to say that the contours are identical and shifted relative to one another so that they are 180 degrees out of phase.

Respective rear side bottom flap32and front side bottom flap36are folded toward each other along the lower transverse fold line62to an orientation which is perpendicular to the longitudinal axis of the packaging container such that both respective bottom flaps32,36lie in a single plane. Each respective rear side bottom flap32and front side bottom flap36are provided in a length that allows the free peripheral edge56of rear side bottom flap32to abuttingly confront the free peripheral edge58of front side bottom flap36when folded. Additionally, the contoured arcs of free peripheral edge56interlock and engage with the contoured arcs of free peripheral edge58so that the respective bottom flaps32,36are prevented from relative motion within the plane of the bottom of the packaging container, and so that respective side walls and end walls of said packaging container are easily formed into and maintained at right angles to and in a non skewed configuration relative to each other. In the preferred embodiment, the respective free peripheral edges56,58are shaped so that the respective free peripheral edges are in mutual contact along their entire length.

In the preferred embodiment, the curvilinear contour is provided in the shape of a sinuate semicircular arc (FIGS. 5 and 17). However, it is well within the scope of this invention to provide the interlocking curvilinear contour in alternative shapes, including square, arcuate, triangular, or some combination or modification of these shapes. Additionally, the amplitude and frequency of the interlocking shape can be modified to accommodate more or less skew correction as required.

In the preferred embodiment, the peripheral edges56,58of the major bottom flaps (rear side bottom flap32and front side bottom flap36) are provided with the interlocking curvilinear contour. However, it is well within the scope of this invention to provide the peripheral edges55,57of the respective minor flaps (first end bottom flap30and second end bottom flap34) with an interlocking curvilinear contour instead of, or in addition to that of the major bottom flaps.

Referring now to FIGS.4and8–10, innovative features on respective front side42and rear side40top flaps will now be discussed. Front side top flap42is defined by upper transverse fold line60which separates it from front side wall28, and a free peripheral edge53which is opposed to upper transverse fold line60and separated from it by the body of the front side top flap42. Front side top flap flange44comprises a narrow portion of front side top flap42immediately adjacent free peripheral edge53, and is provided with an indented transverse fold line64to permit folding of flange44relative to front side top flap42. Plural circular openings90are formed in the body of front side top flap42which are sized to allow bottle caps7to pass therethrough as front side top flap42is folded down to form the top surface of container10. Front side top flap42is provided in a length which allows transverse fold line64to overlie the top edge of rear side wall24when front side top flap42is folded, and which allows flange44to fold about transverse fold line64so that it overlies and confronts an upper portion of rear side wall24.

Rear side top flap40is defined by upper transverse fold line60which separates it from rear side wall24, and a free peripheral edge55which is opposed to upper transverse fold line60and separated from it by the body of the rear side top flap40. Free peripheral edge55is provided with plural semicircular openings92, or crenulations. Openings92are sized to receive the necks7of bottles5therewithin and thus are smaller in dimension than circular openings90of front side top flap42. Rear side top flap40is provided in a length which is approximately ⅔ the distance between front side wall28and rear side wall24.

Rear side top flap40is partially detached from rear side wall24due to die cuts66,67along upper transverse fold line60between first longitudinal fold line70and second longitudinal fold line72. Rear side wall24is provided with a hinge65positioned at transverse fold line60mid way between first longitudinal fold line70and second longitudinal fold line72.

Hinge65connects rear side wall24with rear side top flap40. It consists of an upper transverse perforation line68which coincides with upper transverse fold line60, and a lower transverse perforation line69which lies spaced apart from, parallel to, and below upper transverse perforation line68. Upper transverse perforation line68and lower transverse perforation line69each extend along the middle third of the top edge of rear side wall24, from respective first ends to respective second ends. Each perforation line68,69is provided with evenly space perforations which extend through the thickness of blank20from first face12to second face14. Hinge65further consists of a first longitudinal cut line61which extends between the respective first ends of upper transverse perforation line68and lower transverse perforation line69, and a second longitudinal cut line63which extends between the respective second ends of upper transverse perforation line68and lower transverse perforation line69. First61and second63longitudinal cut lines provide slits in blank20which extend through blank20from first face12to second face14.

Thus, rear side top flap40is detached from rear side wall24along upper transverse fold line60except at hinge65, which provides a pivotable bridge between rear side wall24and rear side top flap40. In use, rear side top flap40is moved laterally outward away from the top edge of rear side wall20(FIG. 9) by pivoting about the lower transverse perforation line69. Then rear side top flap40is pivoted about upper transverse perforation line68such that rear side top flap40lies in the horizontal plane and the semicircular openings92can be inserted about and between necks7of bottles5by urging rear side top flap40toward front side wall28(FIG. 10). Positioning rear side top flap40laterally apart from the rear side wall allows peripheral edge55to avoid interference with bottle caps6as rear side top flap40is folded to the horizontal plane, and eases the insertion of semicircular opening92about necks7of bottles5.

Method steps for forming a container which is consistently square and non-skewed to within strict tolerances will now be described.1. Provide a flat sheet of material from which container10will be formed.2. Die cut the flat sheet of container material into blank20(FIG. 5).3. Apply glue to second face14of end wall flange38.4. Fold blank20along first longitudinal fold line70so that second face14of first end wall22overlies and confronts a first portion of second face14of rear side wall24(FIG. 11).5. Fold blank20along third longitudinal fold line74(FIG. 12)so that second face14of front side wall28overlies and confronts both second face14of second end wall26and a second portion of rear side wall24, andso that second face14of end wall flange38overlies first face12of first end wall22.6. Align longitudinal peripheral edge54of end wall flange38between the cut lines of both the first set80and second set82of alignment markings (FIG. 13).7. Align the center line of third set84of alignment markings between the upper and lower markings of fourth set86of alignment markings, and the center line of fourth set86of alignment markings between the upper and lower markings of third set84of alignment markings (FIG. 13).8. Secure second face14of end wall flange38to first face12of first end wall22by adhesion of glue to form manufacturing joint25on knocked-down container10(FIG. 12).9. Check resulting knocked-down container10to insure that end wall flange38is correctly positioned relative to each respective first, second, third, and fourth set80,82,84,86of alignment markings.10. Erect knocked down container10into an open, hollow tube configuration (FIG. 6).11. Fold first end bottom flap30and second end bottom flap34toward each other along lower transverse fold line62so that first end bottom flap30and second end bottom flap34lie adjacent each other in an orientation which is perpendicular to the longitudinal axis of the packaging container (FIG. 7).12. Fold front side bottom flap36and rear side bottom flap32toward each other along lower transverse fold line62so that front side bottom flap36and rear side bottom flap32lie adjacent each other in an orientation which is perpendicular to the longitudinal axis of the packaging container.13. Position rear side bottom flap32and front side bottom flap36within a single plane so that the curvilinear contour of free peripheral edge58of front side bottom flap36abuttingly engages and interlocks with the complimentary curvilinear contour of free peripheral edge56of rear side bottom flap32, the resulting interlocked configuration preventing the respective bottom flaps32,36from relative motion within the plane of the bottom of container10(FIG. 17).14. Inserting the container contents into the interior space formed within the open, hollow tube of container10such that they rest on respective bottom flaps30,34(FIG. 3).15. Move rear side top flap40laterally outward away from the top edge of rear side wall24by pivoting about lower transverse perforation line69(FIG. 9).16. Fold rear side top flap40to an orientation which is perpendicular to the longitudinal axis of the packaging container by pivoting inward along upper transverse perforation line68.17. Insert crenulated free peripheral edge55of rear side top flap40toward front side wall28so that the crenulations of free peripheral top edge55are inserted between and around the upper portions of the package contents (FIG. 10).18. Fold front side top flap42along upper transverse fold line60toward rear side wall24to an orientation which is perpendicular to the longitudinal axis of the packaging container (FIG. 4).19. Fold front side top flap flange44downward along indented transverse fold line64to overlie and confront first face12of rear side wall24(FIGS. 9 and 10).20. Seal the folded top and bottom ends of container10.