Multi-ply collapsible bulk container

Abstract

A bulk container is disclosed, having a plurality of substantially planar walls, a plurality of corners connecting the walls, and a top and a bottom both formed by a plurality of foldable flaps. A first corner and a second corner opposite the first corner each have two substantially parallel score lines on an inner side of each corner allowing the corners to fold at an angle of substantially 0° while maintaining the structural integrity of the container. The walls of the container are constructed from a multi-ply corrugated cardboard sleeve made up of two layers of multi-ply corrugated cardboard laminated to each other. Two corrugated cardboard inserts, each having foldable top and bottom flaps are laminated to the sleeve. Also disclosed is a method of manufacturing the container using a number of blanks and inserts.

Description

TECHNICAL FIELD

The invention relates generally to a bulk container, and more specifically to a collapsible cardboard container adapted to hold a flowable substance contained in a bag.

BACKGROUND OF THE INVENTION

Large bulk containers are often formed from a generally rectangular blank, usually flat, which has been suitably scored and crushed, by folding certain panels of the blank and then joining the ends of the blank to form a flattened tube structure. After the formation of the blank into a collapsed tube by joining its opposite ends, the packager or final user of the bulk container then unfolds or erects the flattened tube structure into its expanded, tubular condition or configuration, to thereby form a bulk container of generally rectangular configuration. Along those portions of the bulk container which are to be folded to a 0° angle (often termed a reverse fold) in passing from the original, planar blank to the collapsed or knocked down tube, there is, in prior art bulk containers of this type, often significant damage to the structural integrity of the container. The most common such damage is a distortion and tearing caused by compression and/or tension of the paperboard material at these vertically extending edges of the bulk container, where the 0° folds become 90° folds or edges upon refolding 90° attendant set-up or erection. The strength of the erected container is diminished by this damage and the appearance of the container at these folds is also marred.

Increasing the thickness of a container wall increases the compressive, tensile, and shear strength of the wall. Thus, it is desirable to design a container in which walls of greater thickness can be used. However, thicker walls experience greater stresses at the fold lines, particularly when folded to angles approaching 0°. Scoring or crushing corners are known methods to ease the pressure created at a fold line, but prior scoring arrangements and methods have drawbacks. Some are effective only on walls of certain limited thickness. Other designs do not fold tightly, leaving space on the inside of the collapsed container and, more importantly, creating bulges in the material near the reverse fold line. Thus, there exists a need for a container having walls of great thickness that are able to be easily folded flat to an angle of 0° without damage to the structural integrity of the container.

The present invention is provided to solve the problems discussed above and other problems, and to provide advantages and aspects not provided by prior bulk containers of this type. A full discussion of the features and advantages of the present invention is deferred to the following detailed description, which proceeds with reference to the accompanying drawings.

SUMMARY OF THE INVENTION

The present invention provides a bulk container having a plurality of substantially planar walls, a plurality of corners connecting the walls, and a top and a bottom both formed by a plurality of foldable flaps. A first corner and a second corner opposite the first corner each have two substantially parallel score lines on an inner side of each corner allowing the corners to fold at an angle of substantially 0° while maintaining the structural integrity of the container.

In one embodiment, the walls of the container are formed of at least two three-ply corrugated cardboard blanks and at least two two-ply corrugated cardboard inserts, wherein the inserts do not overlap each other. In another embodiment, the walls are formed of two additional three-ply corrugated cardboard blanks. In another embodiment, the walls are formed of at least eight-ply corrugated cardboard sheet. In another embodiment, a third inner corner and a fourth inner corner each have a score line allowing each of the third and fourth corners to fold at an angle of at least 90° while maintaining the structural integrity of the container.

In one embodiment, the inserts are located on an interior of the container. In another embodiment, the inserts are located on an exterior of the container.

The present invention also provides a bulk container constructed from a multi-ply corrugated cardboard sleeve made up of two layers of multi-ply corrugated cardboard laminated to each other. The sleeve is folded to form a plurality of walls and a plurality of corners defining the perimeter of the container. Two corrugated cardboard inserts, each having a foldable top flap and a foldable bottom flap, are laminated to a surface of the sleeve, with each insert extending approximately half the perimeter.

In one embodiment, a first corner and a second corner opposite the first corner each have two substantially parallel score lines on an inner side allowing the first and second corners to fold at an angle of substantially 0° while maintaining the structural integrity of the container. In another embodiment, a third corner and a fourth corner each have a score line allowing each of the third corner and the fourth corner to fold at an angle of at least 90° while maintaining the structural integrity of the container.

In one embodiment, the inserts are laminated to an interior surface of the sleeve. In another embodiment, the inserts are laminated to an exterior surface of the sleeve.

The present invention also provides a method of constructing a bulk container having a top, a bottom, and a plurality of walls. In this method, two cardboard blanks are provided, each having two panels separated by a fold line created by a pair of substantially parallel score lines. An insert is also provided, having a top flap, a bottom flap, and two panels separated by a fold line. First, a surface of the first blank is attached to a surface of the second blank so that the fold line of the first blank is substantially aligned with the fold line of the second blank. Next, a surface of the insert is attached to a surface of the second blank such that one panel of the insert is substantially aligned with one panel of the second blank. Finally, the blanks and the insert are folded at the fold lines to create a number of the walls of the bulk container.

In one embodiment, two additional blanks are provided, each having two panels separated by a fold line created by a pair of substantially parallel score lines. A second insert is also provided, having a top flap, a bottom flap, and two panels separated by a fold line. In this embodiment, a surface of the third blank is attached to a surface of the fourth blank such that the fold line of the third blank is substantially aligned with the fold line of the fourth blank. Then, a surface of the second insert is attached to a surface of the fourth blank such that one panel of the second insert is substantially aligned with one panel of the fourth blank. Next, these additional blanks and inserts are folded at the fold lines to create a number of the walls of the bulk container. Finally, the two container portions are attached to each other to create four walls and four substantially 90° corners of the bulk container.

In another embodiment, the first blank also has a third panel, separated from the second panel by a second fold line created by a score line, and a fourth panel, separated from the third panel by a third fold line created by a pair of substantially parallel score lines, and the second blank also has a third panel, separated from the second panel by a second fold line created by a score line, and a fourth panel, separated from the third panel by a third fold line created by a pair of substantially parallel score lines. A second insert is also provided, having a top flap, a bottom flap, and two panels separated by a fold line. In this embodiment, a surface of the first blank is attached to a surface of the second blank such that the fold lines of each blank are substantially aligned with those of the other blank. Next, a surface of the second insert is attached to a surface of the second blank such that one panel of the second insert is substantially aligned with one panel of the second blank. Finally, the blanks and inserts are folded at the fold lines to create four walls and four substantially 90° corners of the bulk container.

In another embodiment, the pair of substantially parallel score lines allow the first blank and the second blank to fold at substantially a 180° angle while maintaining the structural integrity of the container. In another embodiment, the blanks are each constructed of three-ply corrugated cardboard, and the insert is constructed of two-ply corrugated cardboard. In another embodiment, one blank further comprises a second fold line creating a connecting flap, and the blanks are attached in an offset manner, allowing the connecting flap to fold at the second fold line. In another embodiment, the insert and the blanks are folded such that the first insert is located on an exterior of the bulk container. In another embodiment, the insert and the blanks are attached by laminating with an adhesive.

BRIEF DESCRIPTION OF THE DRAWINGS

To understand the present invention, it will now be described by way of example, with reference to the accompanying drawings in which:

FIG. 1 is a perspective view of a collapsible bulk container having a closed top;

FIG. 2 is a side elevation view of the container of FIG. 1;

FIG. 3 is a perspective view of the container of FIG. 1 having an open top;

FIG. 4 is a cross-section view of the container of FIGS. 1-3, taken along line 4-4 of FIG. 3;

FIG. 5 is an isometric view of the container of FIG. 1 in a collapsed state;

FIG. 6 is a cross-section view of the box of FIG. 4 in a partially collapsed state;

FIG. 7 is a plan view of an insert for use in constructing a collapsible bulk container;

FIG. 8 is a schematic view of a step in a method of manufacturing a collapsible bulk container using a first blank having four fold lines and a similar blank having three fold lines;

FIG. 9 is a plan view of the first blank of FIG. 8, having four fold lines;

FIG. 10 is a schematic view of a step in the method of manufacturing a collapsible bulk container, using the insert of FIG. 7, the blanks of FIG. 8;

FIG. 11 is a plan view of the container of FIG. 1 in a collapsed state;

FIG. 12 is a magnified cross-sectional view of a corner of the collapsed container of FIG. 5;

FIG. 13 is an isometric view of the container of FIG. 1, having an outer layer partially peeled away to illustrate the connection between the layers;

FIG. 14 is a perspective view of a second embodiment of a collapsible bulk container having a closed top;

FIG. 15 is a cross-section view of the container of FIG. 14, taken along line 15-15 of FIG. 14;

FIG. 16 is an isometric view of the container of FIG. 14 in a collapsed state;

FIG. 17 is a magnified cross-sectional view of a corner of the collapsed container of FIG. 16;

FIG. 18 is an isometric view of the container of FIG. 14, having an insert partially peeled away to illustrate the connection between the layers;

FIG. 19 is a schematic view of a step in a second embodiment of a method of manufacturing a collapsible bulk container using two blanks having two fold lines each and two blanks having a single fold line each;

FIG. 20 is a plan view of one blank of FIG. 19 having two fold lines and one blank of FIG. 19 having a single fold line; and

FIG. 21 is a schematic view of a step in the method of manufacturing a collapsible bulk container shown in FIG. 19, using the blanks of FIG. 20 and an insert similar to the insert of FIG. 7.

DETAILED DESCRIPTION

While this invention is susceptible of embodiments in many different forms, there are shown in the drawings and will herein be described in detail preferred embodiments of the invention with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the broad aspect of the invention to the embodiments illustrated.

Referring now to FIGS. 1-21, and initially to FIGS. 1 and 14, there is shown a bulk container 10 having four substantially planar walls 12 and four corners 28, each corner 28 connecting two walls 12, a top 16 formed by four foldable flaps 20, and a bottom 18 formed by four foldable flaps 20. A preferred embodiment is depicted in FIGS. 1-13, and the most preferred embodiment is depicted in FIGS. 14-21. The walls 12 of the container 10 are formed of a sheet material, preferably cardboard. As shown in FIGS. 1 and 14, the container 10 is rectangular, having bi-lateral symmetry (i.e., not square). However, in another embodiment, the container 10 is square. In still further embodiments, the container 10 has a larger or smaller number of walls 12 and corners 28, and one skilled in the art would recognize how to design the container 10 accordingly. The container 10 disclosed is particularly useful for holding a storage bag (not shown) for holding a flowable substance, preferably a storage bag contained in a foldable cardboard cartridge (not shown). In the container 10 shown in FIGS. 1 and 14, the top 16 does not completely enclose the interior, leaving a space 22 to allow for filling the bag inside with liquid or another flowable substance. The bottom 18 is similarly constructed, but the space 23 in the bottom 18 is preferably covered by the cardboard cartridge as the bag is filled. Alternately, the top 16 and/or the bottom 18 can be designed to close completely. Additionally, the container 10 has a drain hole 24 near the bottom of one of the walls 12 to accommodate a drainage spout (not shown) near the bottom of the inner bag. Preferably, the container 10 is collapsible so that it is nearly or completely flat, as illustrated in FIGS. 5-6 and 11. As described below, score lines at the corners 28 of the container 10 facilitate collapsing of the container 10.

Two of the corners 28 each have two substantially parallel score lines 26, which are preferably spaced 2⅝″ apart in the embodiment shown in FIGS. 1-13 and 2¼″ apart in the embodiment shown in FIGS. 14-21. These double-scored corners are indicated by “DS” generally in the FIGS. As shown in FIGS. 12 and 17, the double-scored corners 28 can be folded at an angle of substantially 0°, with little free space remaining. Additionally, the structural integrity of the container 10 is maintained due to the presence of the two score lines 26, and there is little or no crushing, tearing, bulging, distortion, or other permanent damage done to the container 10 by folding at such a sharp angle. In other words, the two score lines 26 allow their respective corners 28 to fold at an angle of substantially 0° while maintaining the structural integrity of the container 10. The other two corners 28 each have a single score line 26 allowing each of those corners 28 to fold at an angle of at least 90° while maintaining the structural integrity of the container 10, as shown in FIGS. 4 and 15. These single-scored corners are indicated by “SS” generally in the FIGS. Preferably, the two double-scored corners 28 are located opposite each other (i.e. diagonally), and the two single-scored corners 28 are located opposite each other as well, as shown in FIGS. 4 and 15. This configuration permits the box to be collapsed into a flattened container 10, as shown in FIGS. 5-6. In the flattened container 10, the two double-scored corners 28 are folded at angles of substantially 0°, and the two single scored corners 28 are unfolded (i.e. are at an angle of substantially 180°). In other embodiments, other scoring arrangements are used, and all corners 28 can be single-scored or double-scored, or may not be scored at all.

In the preferred embodiments, the inner side of each corner 28 is scored, as illustrated in FIGS. 4 and 15. In other words, the inner surface 13 of the container 10 proximate each corner 28 is scored. Since the walls 12 of the container 10 are thick, scoring on the inside may not be visible or detectable from the outside of the container 10. The preferred container 10 has relatively deep score lines 26 on the inner surface 13 of the container 10, extending through most of the thickness of the walls 12 to create the greatest ease of folding.

As shown in FIGS. 12 and 17, the double-scored corners 28 fold tightly and squarely to a 0° angle. Little, if any, discernable space is left on the inside of the collapsed container 10. Further, the outside of the collapsed corner 28 is squared, rather than rounded, and the surface of the collapsed container 10 is flat from edge to edge. This flatness facilitates stacking multiple flattened containers 10, because the completed stack will not wobble due to space between the edges of the containers 10.

Generally, the walls 12 of the container 10 are formed of a sheet material, and are preferably constructed from at least two blanks 30,32 (at least one inner blank 30 and at least one outer blank 32) and two inserts 34, all made of a flexible sheet material. Preferably, the blanks 30,32 and inserts 34 are made from multi-ply corrugated cardboard laminate. Most preferably, the walls 12 of the bulk container 10 are formed of eight-ply corrugated cardboard sheet, as shown in FIGS. 12 and 17. In total, the eight-ply walls 12 are 1⅝″ thick in the preferred embodiment. In other embodiments, other sheet materials are used, including, without limitation, polymers, fiberglass, wood, metal, or combinations thereof. In the eight-ply embodiment shown in FIG. 1, two three-ply blanks 30,32 form the four walls 12 of the container 10, each extending around the entire perimeter of the container 10, and two two-ply inserts 34 are laminated to the inside of the inner blank 30 so that each goes half-way around the perimeter and does not overlap the other. In the most preferred embodiment, four three-ply blanks 30,32 form the four walls 12 of the container 10, each extending half-way around the entire perimeter of the container 10 and overlapping one another, and two two-ply inserts 34 are laminated to the outside of the outer blanks 32 so that each goes half-way around the perimeter and does not overlap the other. In other embodiments, a different number of blanks 30,32 and/or inserts 34 are used, and the blanks 30,32 and inserts 34 have different thicknesses.

The blanks 30,32 are preferably formed from multi-ply corrugated cardboard laminate, most preferably from CAA triple-walled board. In the embodiment shown in FIGS. 1-13, the inner blank 30 and the outer blank 32 are the same length, and have four panels 36 created by three fold lines 14, as shown in FIG. 9. Preferably, two of these fold lines 14 are double-scored and the third fold line 14 is single-scored and located between the two double-scored fold lines 14. As discussed herein, other scoring arrangements are possible. In the embodiment shown in FIGS. 14-21, the inner blanks 30 and the outer blanks 32 are the same length, and have two panels 36 created by a single fold line 14, as shown in FIGS. 19-20. Preferably, this fold line 14 is double-scored. In other embodiments, the blanks 30,32 have a different number of panels 36 and fold lines 14, particularly if the blanks 30,32 are being used to create a container 10 having more than four sides 12. In still further embodiments, the number of panels 36 and fold lines 14 in the outer blanks 32 and the inner blanks 30 can differ. For example, one large outer blank 32 and two or more smaller inner blanks 30 can be used.

Additionally, the outer blank 30 preferably has a small connecting flap 38 created by an additional, single-scored fold line 14. In the preferred embodiments, the inner blank 30 and outer blank 32 are attached so they are slightly offset from one another. In the assembled container 10 shown in FIG. 13, the connecting flap 38 overlaps the opposite end 39 of the inner blank 30 to create more strength and stability in the seam. In the most preferred container 10, the connecting flap 38 of one outer blank 32 overlaps a portion 39 of the second inner blank 30 when the container 10 is assembled, as shown in FIG. 19. In such arrangements, the score lines 26 of the inner 30 and outer blank 32 are also offset to ensure that the score lines 26 of the inner blank 30 are aligned with the score lines 26 of the outer blank 32. In other embodiments, the blanks 30,32 are not offset and no connecting flap 38 is present. In still further embodiments, the offset is more exaggerated, and both blanks 30,32 have a foldable connecting flap 38.

The preferred inserts 34 incorporated in the present container 10 are all very similar to each other. Each insert 34 preferably has two panels 36 created by a single fold line 14, which is single-scored, as shown in FIGS. 7 and 21. One panel 36 is preferably larger than the other, since the preferred container 10 is rectangular. In an alternate embodiment, the panels 36 are of equal size, particularly when the container 10 is shaped as a square or other regular polygon. In some embodiments, only one insert 34 is used, and in other embodiments, more than two inserts 34 are used. In still other embodiments, the inserts 34 have a greater or smaller number of panels 36, particularly if the container 10 has a different number of walls 12, if a different number of inserts 34 are used, or if the inserts 34 overlap each other.

The top flaps 20 and the bottom flaps 20 are preferably formed by foldable portions of the inserts 34, with each insert 34 having two top flaps 20 and two bottom flaps 20. Thus, the thickness of these flaps 20 is smaller than the material of the rest of the container 10, allowing the flaps 20 to be freely foldable without the use of scoring. However, in an alternate embodiment, the fold lines of the flaps 20 are scored. In further embodiments, the flaps 20 have a greater or smaller thickness. In the preferred embodiments, the top and bottom flaps 20 are identical to each other. Each of the top flaps 20 has either two flanges 40 or slots 42 to interlock with the respective slots 42 or flanges 40 of the adjacent flaps 20 when the flaps 20 are folded inward. Once interlocked, these top flaps 20 form the top 16 of the container 10. The bottom flaps 20 are similarly constructed to form the bottom 18 of the container 10. The preferred inserts 34 have one flanged top flap 20, one slotted top flap 20, one flanged bottom flap 20, and one slotted bottom flap 20. One skilled in the art would recognize that the orientation of the flaps 20 shown in FIG. 7 can be switched by flipping the insert 34 over (i.e. 180°). Additionally, various means of interlocking or otherwise connecting flaps 20 to close the top 16 of a container 10 are known and may be used. Further, in other embodiments, no top and/or bottom flaps 20 are present, and other means to close the container 10 can be used. In still other embodiments, the top flaps 20 and bottom flaps 20 are very different from each other.

In the embodiment shown in FIGS. 1-13, the two inserts 34 used are preferably identical to each other. Likewise, the inserts 34 used in the embodiment shown in FIGS. 14-21 are preferably identical to each other. However, the inserts 34 used in each of these embodiments differs slightly from those used in the other, as can be seen by observing FIGS. 7 and 21. Primarily, the flaps 20 in FIG. 7 are more widely spaced near the fold line 14, but extend farther from the outer edge of the insert 34, than the flaps 20 shown in FIG. 21.

When assembled, the inner blanks 30 are connected to the inner surfaces of the outer blanks 32, preferably by laminating with glue or other adhesive 44. The connected inner 30 and outer blanks 32 form a sleeve 46. Preferably, the inner blank(s) 30 form an inner layer 48 extending completely around the perimeter of the container 10, and the outer blank(s) 32 form an outer layer 50 extending completely around the perimeter. All corners 28, as well as the shape of the container 10, are, therefore, preferably defined by the sleeve 46. In the preferred embodiments, the sleeve 46, as well as each layer 48,50, is made of multi-ply corrugated cardboard and defines the four corners 28 and the rectangular perimeter of the container 10. Most preferably, the sleeve 46 is made of six-ply corrugated cardboard, or two layers 48,50 of three-ply corrugated cardboard. In the preferred embodiments, the sleeve 46 has two single-scored corners 28 and two double-scored corners 28, as described above.

In the embodiment illustrated in FIGS. 1-13, both the inner 30 and outer blanks 32 extend around the perimeter of the container 10. The connecting flap 38 of the outer blank 32 overlaps the opposite end 39 of the inner blank 30 to form a secure connection, as shown in FIG. 13. In the embodiment shown in FIGS. 14-21, each blank 30,32 extends half-way around the perimeter of the container 10. Each inner-outer blank pair 30,32 (as shown in FIG. 21) forms a half-container 11, which is attached to another half-container 11 to form a full container 10. The connecting flap 38 of each half-container 11 overlaps a portion 39 of the inner blank 30 of the other half-container 11 to ensure strong connection. If a greater number of blanks 30,32 are used, each blank 30,32 will extend around a smaller fraction of the perimeter.

The inserts 34 are connected to a surface of the sleeve 46, preferably by laminating. In the embodiment shown in FIGS. 1-13, the two inserts 34 are laminated to the inner surface of the sleeve 46. Conversely, in the embodiment shown in FIGS. 14-21, the two inserts 34 are laminated to the outer surface of the sleeve 46. Preferably, neither of the two inserts 34 extends completely around the perimeter of the container 10 nor overlaps the other insert 34. In other embodiments, the inserts 34 overlap each other, and can extend around the complete perimeter of the container 10. In still other embodiments, adhesive is not used to connect the blanks and inserts 34, and any suitable means of connection known in the art can be used. In the embodiment of FIGS. 1-13, the score line 26 of each insert 34 is aligned with the single-scored fold lines 14 of the blanks 30,32. In the most preferred embodiment, the score line 26 of each insert 34 is aligned with the single-scored fold line 14 of each outer blank 32, adjacent the connecting flap 38. The edges of the inner blanks 30 form a juncture in alignment with the single-scored fold line 14, so no additional scoring of the inner blank 30 is necessary. Since the fold lines 14 of the blanks 30,32 and inserts 34 are aligned in the assembled container 10, the panels 36 of the inserts 34 are dimensioned to be approximately the same size as the corresponding panels 36 of the blanks 30,32. In this arrangement, each insert 34 covers two panels 36 of the inner blank 30, extending substantially to the double-scored fold lines 14, but not farther. Thus, the inserts 34 leave the double-scored corners 28 of the container 10 uncovered, so as not to interfere with the 0° fold, as illustrated in FIGS. 12 and 17. In other embodiments, the inserts 34 cover the double-scored corners 28 and can have double-scored fold lines. Further, if different blanks 30,32 or inserts 34 are used, the blanks and inserts 34 are connected in other manners.

In the most preferred embodiment, the inserts 34 are on the outside of the container 10, as described above. Thus, the flaps 20 extend over the inner plies of the container 10 towards the center of the blank, covering the entire thickness of the container walls 12 and protecting their edges from damage, as shown in FIG. 14. In some cases, the edges may sustain damage during stacking and transporting. Accordingly, this embodiment is well-suited to prevent such damage. In the other preferred embodiment, shown in FIG. 1, the inserts 34 are on the inside of the container 10 and do not overlap the rest of the wall 12.

Additionally, the inner blank 30, the outer blank 32, and at least one of the inserts 34 preferably has a hole 24 near the bottom 18 to create the drain hole 24 in the container wall 12, and each of these holes 24 are aligned in the assembled container 10.

One preferred method of manufacturing the container 10 utilizes two four-panel 36 blanks 30,32 and two two-panel 36 inserts 34, as described above, and is illustrated in FIGS. 7-10. This method may be used to create the container 10 illustrated in FIGS. 1-6 and 11 -13. The outer blank 32 has four fold lines 14 creating four panels 36 and a connecting flap 38, and the inner blank 30 has three fold lines 14 creating four panels 36, as shown in FIGS. 8 and 9. The outer blank 32 and the inner blank 30 are attached together in an offset manner as shown in FIG. 8. The first insert 34 is then attached to the surface of the inner blank 30 so that the single-scored fold line 14 of the insert 34 is aligned with the single scored fold line 14 of the inner blank. In this arrangement, the two panels 36 of the first insert 34 cover two of the panels 36 of the inner blank 30, leaving two other panels 36 of the inner blank 30 uncovered, illustrated in FIG. 10. Preferably, the coverage of the insert 34 extends from one double-scored fold line 14 to the other double-scored fold line 14, but does not cover either of the two double-scored fold lines 14, as described above.

After the first insert 34 has been attached to the inner blank 30, the second insert 34 is lain on the first insert 34, preferably flipped over (180°), as shown in FIG. 10. The two free, uncovered panels 36 of the inner blank 30 are then folded inward to cover the second insert 34, thereby attaching the inner blank 30 to the second insert 34. The outer blank 32 is also folded inward during this step, since it is attached to the inner blank 30, and the connecting flap 38 overlaps, and is attached to, a portion of the inner blank 30. Completion of this step forms a flattened container 10, as described above, having four walls 12 (two on the top side, two on the underside) with four fold lines 14, as shown in FIGS. 5 and 11. Two of the fold lines 14 are at the edges of the flattened container 10, folded at substantially 0° angles, and the other two fold lines 14 are proximate the middle of the flattened container 10, unfolded to substantially 180° angles. Finally, the bulk container 10 is formed by folding the four fold lines 14 to an angle of 90° to form a four-walled rectangular container 10, shown in FIGS. 1-3. The container 10 is shown in a partially-collapsed state in FIG. 6, to illustrate how the container 10 folds and unfolds between expanded and collapsed states. Preferably, the three fold lines 14 of the inner blank 30 and the fold line 14 of the connecting flap 38 form the four corners 28 of the assembled container 10.

The most preferred method of manufacturing the container 10 of the present invention is illustrated in FIGS. 19-21, and utilizes four two-panel 36 blanks (two inner 30 and two outer blanks 32) and two two-panel 36 inserts 34, as described above. This method may be used to create the container 10 illustrated in FIGS. 14-18. Each outer blank 32 has two fold lines 14 creating two panels 36 and a connecting flap 38, and each inner blank 30 has one fold line 14 creating two panels 36, as shown in FIGS. 19-20. Each outer blank 32 is attached to one of the inner blanks 30 in an offset manner as shown in FIG. 19. Each insert 34 is then attached to the outer surface of one of the outer blanks 32 so that the single-scored fold line 14 of the insert 34 is aligned with the single-scored fold line 14 at the connecting flap 38. In this arrangement, one panel 36 of the insert 34 covers one panel 36 of the outer blank 32, while the other panel 36 of the insert 34 covers only the connecting flap 38, with a portion 52 of the insert 34 extending past the outer edge of both the inner 30 and outer blanks 32, as shown in FIG. 21. Preferably, the coverage of the insert 34 extends to the double-scored fold line 14 of each blank, but does not cover the double-scored fold line 14, as described above.

After this step, two identical half-containers 11 have been created, each containing one inner blank 30, one outer blank 32, and one insert 34. One such half-container 11 is depicted in FIG. 21. The final step in manufacturing is to connect the two half-containers 11 together to form a full container 10, as illustrated in FIG. 18. In this connection, the connecting flap 38 of the outer blank 32 of each half-container 11 attaches to the overlapping portion 39 of the inner blank 30 of the other half-container 11, and the overlapping portion 50 of the insert 34 of each half-container 11 connects to the uncovered panel 36 of the outer blank 32 of the other half-container 11. Preferably, the two double-scored fold lines 14 and the two single scored fold lines 14 adjacent the connecting flaps 38 form the four corners 28 of the assembled container 10. This assembled container 10 collapses and expands as described above, and illustrated in FIGS. 16 and 17.

In the preferred methods of manufacturing the bulk container 10, the blanks 30,32 and inserts 34 are attached together by laminating with glue or other adhesive 44. However, many other suitable means of attaching such structures together are known in the art, and can be used with the disclosed method. Further, the most effective means of attachment can vary, if a different material is used for the blanks 30,32 and inserts 34.

The present method also preferably includes scoring the blanks 30,32 and inserts 34, preferably by die-cutting straight lines 26 in the surface of the cardboard with a scoring tool. This tool causes deep compression in the walls 12 along the score lines 26. In multi-ply walls 12, the scoring preferably extends through each ply of the walls 12, as shown in FIGS. 4, 12, 15, and 17. Any other known scoring method is suitable for use in the disclosed method, including blade-cutting or pressing. As discussed above, one preferred inner blank 30 has three scored fold lines 14, as shown in FIGS. 9-10. Two of the fold lines 14 are double-scored, i.e., having a set of two parallel score lines 26 on the surface of the blank 30. A third fold line 14, preferably located between the first and second fold lines 14, is single-scored, having only a single score line 26. The corresponding outer blank 32 has the same three scored fold lines 14 as the inner blank, but contains an additional single-scored fold line 14 at the connecting flap 38, as shown in FIG. 10. In the most preferred embodiment, each inner blank 30 has one double-scored fold line 14, and each outer blank 32 has one double-scored fold line 14 and an additional single-scored fold line 14 at the connecting flap 38, as described above and illustrated in FIG. 20.

Each insert 34 preferably has a single fold line 14 that is single-scored, also illustrated in FIG. 10. Preferably, all score lines 26 are straight and parallel to their respective fold lines 14, however other score line 26 configurations may be used with the present container 10. Scoring can be done at any point during the manufacturing process. In the most preferred method, the blanks 30,32 and inserts 34 are scored prior to assembly, and measured carefully to ensure the score lines 26 will all be aligned properly when assembled. In other embodiments, the blanks 30,32 and inserts 34 are scored after assembly or at some point during the assembly process.

The disclosed method can be modified without departing from the scope of the present invention. Most importantly, the present invention contemplates the addition of other steps and components to the method. For example, although the preferred method calls for the use of two blanks 30,32 and two inserts 34, additional blanks 30,32 and/or inserts 34 can be used. Also, the method can incorporate differently-sized blanks 30,32 and inserts 34. Indeed, since the disclosed method is useful in manufacturing containers having shapes other than rectangular, the use of other blanks 30,32 or inserts 34 is desirable in many embodiments. One skilled in the art would understand how to attach and score these additional blanks 30,32 and inserts 34 in keeping with the disclosed method. Similarly, additional or fewer folding or scoring steps are used in some embodiments, particularly in containers of different shapes and if a different size or number of blanks 30,32 or inserts 34 are used. In another embodiment, the flaps 20 are separate and must be attached to the container 10 as well.

The disclosed container is particularly useful for handling liquids or other flowable materials contained in an impermeable bag held within the container. Most advantageously, the bag is held within a cardboard cartridge configured to sit at the bottom of the container when the bag is filled, covering the open bottom. Such bags, when filled, often weigh around 2000 lb. The open top allows for the bag to be filled and the drain hole allows for draining liquid from the bag, preferably through a drain spout. The strength created by the eight-ply corrugated cardboard walls of the container increase the vertical compressive strength of the container, maximizing stacking height. The added strength also helps to protect and support the bag contained within.

A chief benefit of the disclosed container is the ease of collapsing, stacking, and storing the container. The score lines allow the container, despite having thick, sturdy walls, to collapse to a flattened shape having a minimum possible thickness with no gaps between the material. This collapsed container 10 is shown in FIG. 6. Once flattened, the container can be stably stacked with other collapsed containers for easy, compact storage and transporting. When needed, the collapsed container is quickly and readily expandable to its working form.

The terms “first,” “second,” “third,” “fourth,” etc., as used herein are intended for illustrative purposes only and do not limit the embodiments in any way. Further, the term “plurality” as used herein indicates any number greater than one, either disjunctively or conjunctively, as necessary, up to an infinite number.

While the specific embodiments have been illustrated and described, numerous modifications come to mind without significantly departing from the spirit of the invention, and the scope of protection is only limited by the scope of the accompanying claims.

Claims

1. A bulk container comprising:

a plurality of substantially planar walls;

a plurality of corners, each corner connecting two walls, wherein a first corner and a second corner opposite the first corner each have two substantially parallel score lines on an inner side allowing the first and second corners to fold at an angle of substantially 0° while maintaining the structural integrity of the container;

a top formed by a plurality of foldable flaps; and

a bottom formed by a plurality of foldable flaps.

2. The bulk container of claim 1 wherein the walls are comprised of at least first and second three-ply corrugated cardboard blanks and at least first and second two-ply corrugated cardboard inserts, wherein the inserts do not overlap each other.

3. The bulk container of claim 2, wherein the walls are further comprised of at least third and fourth three-ply corrugated cardboard blanks.

4. The bulk container of claim 3, wherein the inserts are located on an interior of the container.

5. The bulk container of claim 3, wherein the inserts are located on an exterior of the container.

6. The bulk container of claim 1, wherein a third inner corner and a fourth inner corner each have a score line allowing each of the third and fourth corners to fold at an angle of at least 90° while maintaining the structural integrity of the container.

7. The bulk container of claim 1, wherein each wall is formed of at least eight-ply corrugated cardboard sheet.

8. A bulk container comprising:

a multi-ply corrugated cardboard sleeve comprised of a first layer of multi-ply corrugated cardboard laminated to a second layer of multi-ply corrugated cardboard, the sleeve folded to form a plurality of walls and a plurality of corners defining a perimeter;

a first corrugated cardboard insert comprising a foldable top flap and a foldable bottom flap and laminated to a surface of the sleeve, the first insert extending approximately half the perimeter; and

a second corrugated cardboard insert comprising a foldable top flap and a foldable bottom flap and laminated to a surface of the sleeve, the second insert extending approximately half the perimeter and separate from the first insert,

wherein the top flaps fold inward to form a top of the container and the bottom flaps fold inward to form a bottom of the container.

9. The bulk container of claim 8, wherein the first and second inserts are laminated to an interior surface of the sleeve.

10. The bulk container of claim 8, wherein the first and second inserts are laminated to an exterior surface of the sleeve.

11. The bulk container of claim 8, wherein a first corner and a second corner opposite the first corner each have two substantially parallel score lines on an inner side allowing the first and second corners to fold at an angle of substantially 0° while maintaining the structural integrity of the container.

12. The bulk container of claim 11, wherein a third corner and a fourth corner each have a score line allowing each of the third corner and the fourth corner to fold at an angle of at least 90° while maintaining the structural integrity of the container.

13. A method of constructing a bulk container having a top, a bottom, and a plurality of walls, comprising the steps of:

providing a first blank comprising a first panel and a second panel separated by a first fold line comprising a pair of substantially parallel score lines;

providing a second blank comprising a first panel and a second panel separated by a first fold line comprising a pair of substantially parallel score lines;

attaching a surface of the first blank to a surface of the second blank such that the fold line of the first blank is substantially aligned with the fold line of the second blank;

providing a first insert comprising a top flap, a bottom flap, and a first panel and a second panel separated by a fold line;

attaching a surface of the first insert to a surface of the second blank such that the first panel of the first insert is substantially aligned with one of the first panel and the second panel of the second blank; and

folding the first blank, the second blank, and the first insert at the fold lines to create a number of the walls of the bulk container.

14. The method of claim 13, further comprising the steps of:

providing a third blank comprising a first panel and a second panel separated by a fold line comprising a pair of substantially parallel score lines;

providing a fourth blank comprising a first panel and a second panel separated by a fold line comprising a pair of substantially parallel score lines;

attaching a surface of the third blank to a surface of the fourth blank such that the fold line of the third blank is substantially aligned with the fold line of the fourth blank;

providing a second insert comprising a top flap, a bottom flap, and a first panel and a second panel separated by a fold line;

attaching a surface of the second insert to a surface of the fourth blank such that the first panel of the second insert is substantially aligned with the first panel of the fourth blank;

folding the third blank, the fourth blank, and the second insert at the fold lines to create a number of the walls of the bulk container; and

attaching the number of walls created by the first blank, the second blank, and the first insert to the number of walls created by the third blank, the fourth blank, and the second insert to create four walls and four substantially 90° corners of the bulk container.

15. The method of claim 13, wherein the first blank further comprises a third panel, separated from the second panel by a second fold line comprising a score line, and a fourth panel, separated from the third panel by a third fold line comprising a pair of substantially parallel score lines, and the second blank further comprises a third panel, separated from the second panel by a second fold line comprising a score line, and a fourth panel, separated from the third panel by a third fold line comprising a pair of substantially parallel score lines, further comprising the steps of:

attaching a surface of the first blank to a surface of the second blank such that the first fold line of the first blank is substantially aligned with the first fold line of the second blank, the second fold line of the first blank is substantially aligned with the second fold line of the second blank, and the third fold line of the first blank is substantially aligned with the third fold line of the second blank;

providing a second insert comprising a top flap, a bottom flap, and a first panel and a second panel separated by a fold line;

attaching a surface of the second insert to a surface of the second blank such that the first panel of the second insert is substantially aligned with one of the third panel and the fourth panel of the second blank; and

folding the first blank, the second blank, the first insert, and the second insert at the fold lines to create four walls and four substantially 90° corners of the bulk container.

16. The method of claim 13, wherein the pair of substantially parallel score lines allow the first blank and the second blank to fold at substantially a 180° angle while maintaining the structural integrity of the container.

17. The method of claim 13, wherein the first blank is comprised of three-ply corrugated cardboard, the second blank is comprised of three-ply corrugated cardboard, and the insert is comprised of two-ply corrugated cardboard.

18. The method of claim 13, wherein the second blank further comprises a second fold line creating a connecting flap, and the first blank and the second blank are attached in an offset manner, allowing the connecting flap to fold at the second fold line.

19. The method of claim 13, wherein the first blank, the second blank, and the first insert are folded such that the first insert is located on an exterior of the bulk container.

20. The method of claim 13, wherein the first blank, the second blank, and the first insert are attached by laminating with an adhesive.