WO2007093979A2

WO2007093979A2 - Strengthening stackable corrugated cardboard containers

Info

Publication number: WO2007093979A2
Application number: PCT/IL2006/001243
Authority: WO
Inventors: Yosi Shabi
Original assignee: Cargal Ltd.
Priority date: 2006-02-14
Filing date: 2006-10-29
Publication date: 2007-08-23
Also published as: IL173732A0; WO2007093979A3

Abstract

A reinforced corrugated cardboard container formed from a folded up corrugated cardboard blank (100) includes a bottom formed from a central generally rectangular area (110) of the blank and four walls formed by folding upward flaps (120, 130) extending from the rectangular area of the blank, four corners each formed by folding over an extension piece (160) of a folded upward flap (120, 130), which extends in size beyond the rectangular area and attaching the extension piece (160) to the folded upward flap of an adjacent wall of the container. One or more of the corners are reinforced by additionally folding the extension piece of the folded upward flap forming the corner to form an indentation to the container wall it is attached to, such that a void (145) is formed by the extension piece of the flap between the resulting wall and a virtual straight wall defined by the central generally rectangular area.

Description

STRENGTHENING STACKABLE CORRUGATED CARDBOARD

CONTAINERS

FIELD OF THE INVENTION The present invention relates generally to strengthening the ability of stackable corrugated cardboard containers to withstand a load.

BACKGROUND OF THE INVENTION

Corrugated cardboard containers are commonly used for marketing products, for example fruits and vegetables, poultry and meat, and other items.

Typically during transport a plurality of containers are stacked up one on top of each other and multiple stacks are placed next to each other on a platform, so that they can readily be moved with a fork-lift.

In order for the products to be transported without damage the containers are required to be able to withstand heavy loads. Typically, a container on the bottom of a stack may need to withstand loads as great as a hundred kilograms or more.

Typically it is desired that the containers be created from a single blank cut from a sheet of laminated corrugated cardboard, in order to simplify manufacture of the containers. In order to provide the containers with sufficient strength to withstand loads as mentioned above a first common practice is to reinforce the sides and/or corners by designing the blank to be folded over to form a container with sides and corners with two layers of cardboard. Another common practice is to have at least two sides and the reinforced corners made of corrugated cardboard with the flute run direction running perpendicular to the stacking plane.

US patent application publication 2004/0256448 the disclosure of which is incorporated herein by reference describes a container formed from a single blank that incorporates the common practices described above. Another consideration in designing containers which may be in contradiction to the strength consideration is to provide for air flow with access of the air to all containers when stacked up in multiple rows and columns. Airflow is especially important for products which are transported in refrigerated containers or that require fresh air to preserve freshness. Typically the blank may be designed with certain portions cut out, to allow air to reach all the containers even those in the inner stacks. Some of the cut out portions may serve a dual purpose, for example to allow a person to hold the container and/or to match stack indexes, which help maintain the stack-ability of the containers by preventing the containers from moving relative to each other.

SUMMARY OF THE INVENTION

An aspect of an embodiment of the invention relates to a corrugated cardboard container with reinforced corners that is produced from a folded up blank of corrugated cardboard. The blank is pre-cut to a specific layout that is provided with a central generally rectangular area to serve as the bottom of the container, with flaps extending from the bottom to be folded up to form the walls of the container. A corner is formed by folding over an extension of a flap beyond the length/width of the rectangular area that it is folded up from and attaching the folded over extension to an adjacent wall formed from a different flap. In order to reinforce the corner the folded over flap is further folded forming an indentation that forms a void with a projection over the generally rectangular bottom. The indentation disturbs the generally rectangular shape of the walls of the container, while the corner points maintain the generally rectangular shape of the container.

Optionally, the projection of the void on the bottom forms an arc, semi-circle, trapezoid or a triangle.

In an exemplary embodiment of the invention, the indentation of a single corner offsets up to 20 percent of the length of the affected wall. Alternatively, the indentation of a single corner offsets up to 50 percent of the length of the affected wall. Optionally, the minimum cross section of the void formed by the indentation is at least twice as thick as the thickness of the corrugated cardboard, in order to effectively reinforce a corner. The maximum cross section of the void is less than a third or a fourth of the length of the wall perpendicular to the offset wall, so that the container can be used for storage.

In some embodiments of the invention, additional pieces of cardboard are attached to the folded up container to preserve its form. In some embodiments of the invention, the shape. of the central rectangular area is precut to remove the area formed by the projection of the void on the bottom of the container to enhance airflow. Alternatively, the central rectangular area remains rectangular regardless of the shape of the void formed by indenting the wall of the container to block airflow. In some embodiments of the invention, the flaps comprise additional extensions which are folded over and glued to the internal walls to reinforce them, for example by forming double layered walls and/or providing an overhead support to preserve the structure of the container. In some embodiments of the invention, all corners are reinforced.

Alternatively only selected corners are reinforced. In some embodiments of the invention, different corners have different size reinforcements, for example forming different sized voids and/or in different positions near the comer.

There is thus provided according to an exemplary embodiment of the invention, a reinforced corrugated cardboard container formed from a folded up corrugated cardboard blank, including: a bottom formed from a central generally rectangular area of the blank, four walls formed by folding upward flaps extending from the rectangular area of the blank, four corners each formed by folding over an extension piece of a folded upward flap, which extends in size beyond the rectangular area, and attaching the extension piece to the folded upward flap of an adjacent wall of the container, wherein one or more of the corners are reinforced by additionally folding the extension piece of the folded upward flap forming the corner, to form an indentation to the container wall it is attached to. such that a void is formed by the extension piece of the flap between the resulting wall and a virtual straight wall defined by the central generally rectangular area. Optionally, the projection of the void on the bottom forms a triangle. Alternatively, the projection of the void on the bottom form a semi-circle.

Further alternatively, the projection of the void on the bottom form a trapezoid.

In some embodiments of the invention, the indentation offsets up to 20 percent of the wall with the indentation. Alternatively, the indentation offsets up to 50 percent of the wall with the indentation. Optionally, the indentation position is next to the corner in the first quarter of the length of the container. In some embodiments of the invention, the cross section of the void formed by the indentation is at least twice the size of the thickness of the corrugated cardboard. Optionally, the projection of said void on the bottom is precut from the blank. In some embodiments of the invention, part of the cardboard forming the indentation is adhesively attached to the other wall of the comer.

In some embodiments of the invention, the indentation is secured by a flap attached to the top of the indentation. Optionally, the securing flap is part of the blank. Alternatively, the securing flap is not part of the blank. In some embodiments of the invention, the container further comprises an extension to one or more flaps to form a container with double layered walls. Optionally, the container further comprises an extension to one or more flaps to secure the indentation. In some embodiments of the invention, all corners of the container are reinforced. Optionally, the reinforcement of the corners is performed by one indentation to each wall of the container. In some embodiments of the invention, the reinforcement of the corners is performed by two indentations to two walls of the container. Alternatively, selected corners of the container are reinforced. In some embodiments of the invention, the length and width of the generally rectangular bottom are substantially identical.

There is additionally provided in accordance with an exemplary embodiment of the invention, a method of producing a corrugated cardboard container with reinforced corners, including: providing a corrugated cardboard blank with a central generally rectangular area and flaps extending from the four sides of the generally rectangular are, folding up the flaps to create wall for the container, creating corners for the container by folding over an extension piece of a folded upward flap, which extends in size beyond the rectangular area, and attaching the extension piece to the folded upward flap of an adjacent wall of the container, reinforcing the corners by additionally folding the extension piece of the folded upward flap forming the corner, to form an indentation to the container wall it is attached to, such that a void is formed by the extension piece of the flap between the resulting wall and a virtual straight wall defined by the central generally rectangular area. Optionally, the reinforcing is performed after creating the container with non-reinforced corners. In some embodiments of the invention, the reinforcing is performed by applying a force to the external side of the walls of the container. Optionally, the indentation also bends the flap forming the adjacent wall.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be understood and appreciated more fully from the following detailed description taken in conjunction with the drawings.

Identical structures, elements or parts, which appear in more than one figure, are generally labeled with the same or similar number in all the figures in which they appear, wherein:

Fig. 1 is a schematic illustration of the layout of a blank for preparing corrugated cardboard containers with reinforced corners, according to an ^• exemplary embodiment of the invention; Fig. 2 is a schematic illustration of a corrugated cardboard container with reinforced corners created from the blank of Fig. 1, according to an exemplary embodiment of the invention;

Fig. 3 is a schematic illustration of a corrugated cardboard container with reinforced corners and a position securing flap, according to an exemplary embodiment of the invention;

Fig. 4 is a schematic illustration of the layout of a blank for preparing corrugated cardboard containers with double layered walls and with reinforced corners, according to an exemplary embodiment of the invention;

Fig. 5 is a schematic illustration of a corrugated cardboard container with double layered walls and with reinforced comers created from the blank of Fig. 4, according to an exemplar}' embodiment of the invention;

Fig. 6 is a schematic illustration of a stack of containers on a platform, according to an exemplary embodiment of the invention; and

Fig. 7 is a schematic illustration of an alternative layout of a blank for preparing corrugated cardboard containers with reinforced corners, according to an exemplary embodiment of the invention. DETAILED DESCRIPTION

Fig. 1 is a schematic illustration of the layout of a blank 100 for preparing corrugated cardboard containers with reinforced corners, according to an exemplary embodiment of the invention. In an exemplary embodiment of the invention, blank 100 comprises a central generally rectangular area 110 with flaps 120 and 130 extending from the four sides of area 110. Flaps 130 are designed to produce two walls of the cardboard container with reinforced comers by folding them up from the plane of blank 100. Optionally, flaps 120 are also folded up and attached (e.g. adhesively or with other means such as staples) to the corners that are formed from flaps 130. In an exemplary embodiment of the invention, flaps 130 extend with an excess piece 160 beyond the extent (length/width) of the side of the generally rectangular area 110 they extend from in order to provide a complete wall surrounding the container.

Typically in prior art container production, excess piece 160 is folded at a right angle along a crease line 140, relative to flap 130 to produce a corner for the container. In an exemplary embodiment of the invention, excess piece 160 is folded over to form an obtuse angle, for example approximately 135 degrees or approximately 180 degrees instead of 90 degrees. Then excess piece 160 is folded back at an acute angle along a second crease line 150 to form a corner with an indentation relative to the general rectangular shape of area 1 10. Optionally, flaps

120 are folded up to form walls perpendicular to the walls formed from flaps 130.

In an exemplar}' embodiment of the invention, an end of excess piece 160 is folded along crease line 155 and attached (e.g. adhesively or with other means such as staples) to an end piece of flap 120 folded along crease line 125. In an exemplary embodiment of the invention, the folded corner forms a void with a projection on area 110, which defines a base 145 in the shape of a triangle. In some embodiments of the invention, blank 100 is prepared with base 145 cut out from blank 100 to enhance airflow. Alternatively, blank 100 may be provided as a rectangle without cutting out base 145. In some embodiments of the invention, a cross section of base 145 is at least twice the size of the thickness of the corrugated cardboard. Optionally, the length of the wall offset by the indentation is up to 20 percent of the length of the indented wall. Alternatively, the length of the wall offset by the indentation is up to 50 percent of the length of the indented wall. In an exemplary embodiment of the invention, the indentation position is next to the corner in the first quarter or the first third of the length of the container.

In some embodiments of the invention, reinforcement of the corner is performed after producing a container with non-reinforced corners and then applying a force from the external side of the container to form the indentation. Optionally, the corners are held together using slow drying glue so that the indentation is formed before the glue hardens.

In some embodiments of the invention, the flap 120 is also folded as part of the indentation at the attachment point with excess piece 160.

Fig. 2 is a schematic illustration of a corrugated cardboard container 200 with reinforced corners created from the blank of Fig. 1 as described above, according to an exemplary embodiment of the invention. In some embodiments of the invention excess piece 160 is partially attached to flap 130 and partially attached to flap 120 as shown in Fig. 2 in order to preserve its position. In some embodiments of the invention, excess piece 160 is folded to form a void with base 145 in the shape of an arc or other shapes other than a triangle.

In an exemplary embodiment of the invention, the flute direction for preparing blanks 100 is selected so that flaps 130, when folded up to form a container, will be perpendicular to the plain of area 110, which serves as the base of the container. This selection provides the walls of the container with the maximum strength for supporting stacks of containers or other loads. In an exemplar}' embodiment of the invention, the strength of the corners is reinforced as described above by rearranging their geometry without addition of extra material. Compression tests have shown that the above reinforcement of a corner adds at least 10-25% to the strength of the corner. Compression tests are typically performed using a compression machine such as a compression load tester manufactured by Testing Machines Inc. (www.testinamachines.com). which pushes down on a container with an increasing force until it collapses. Such compression tests have shown for example that a container which crushes at 1.2 tons would withstand up to 1.45 tons when reinforcing the corners. In some embodiments of the invention, blank 100 for forming containers 200 is provided with a hand grasp hole 180, which enhances the ability to cany containers 200. In some embodiments of the invention, blank 100 is provided with a stack index 170 and matching stack holes 190 to support stacking of containers 200 while preventing them from moving relative to each other. In some embodiments of the invention, blank 100 is provided with additional airflow holes 195 to enhance airflow, for example when containers 200 are stacked up.

In some embodiments of the invention, the containers 200 can be folded by hand or with the help of hand tools. Alternatively, dedicated machines for folding up boxes such as manufactured by Boix (www.orupoboix.com) are used to create the reinforced containers. Optionally, by adding a solid piece of material to specific places of a folding machine, the machine is amended to automatically form an indentation to the external walls of the container while folding up and attaching the walls of the container as described above.

Fig. 3 is a schematic illustration of a corrugated cardboard container 300 with reinforced corners and position securing flaps 330, according to an exemplary embodiment of the invention. Fig. 3 shows 2 position securing flaps 330 one for each end of the container. One of position securing flaps 330 is shown before being attached to the container and the other is shown after being attached. Optionally, position securing flaps 330 provide additional .support to maintain the indentation position formed to reinforce the corners of the corrugated cardboard containers as described above. In some embodiments of the invention, position securing flap 330 is an integral part of blank 100 stemming from flap 130. Alternatively, position securing flap 330 is an external piece of corrugated cardboard which is added on to the container. Fig. 4 is a schematic illustration of the layout of a blank 400 for preparing corrugated cardboard containers with double layered walls and with reinforced corners, according to an exemplary embodiment of the invention. Fig.

5 is a schematic illustration of a corrugated cardboard container with double layered walls and with reinforced corners created from the blank of Fig. 4, according to an exemplary embodiment of the invention. In an exemplary embodiment of the invention, blank 400 is provided with a layout for producing a corrugated cardboard container 500, which is similar to corrugated cardboard container 200, except that blank 400 is provided with a larger flap with two parts: a lower pail 420 for producing the external wall of corrugated cardboard container

500 and an upper part 410 for producing an inner wall of corrugated cardboard container 500. Corrugated cardboard container 500 provides enhanced strength by doubling the thickness of the walls. In some embodiments of the invention, the inner walls are used to provide truncated corners so as not to interfere with the reinforcement of the outer walls. Alternatively, the inner walls may be coupled to the outer walls. Optionally, when the inner walls form truncated comers the reinforced corners do not affect the volume of the container since the indentation is performed in a position which is external to the inner wall of the container.

Fig. 6 is a schematic illustration of a stack of containers 600 on a platform 640, according to an exemplary embodiment of the invention. Some products are transported with refrigeration or with heating or require fresh air to preserve freshness of the produce being transported. Optionally, the void formed by reinforcing the corners when the base under the void is cut out from the blank used to create the container, provides additional paths for air flow. These paths enhance even distribution of air to the products being transported in addition to standard air flow holes such as 620 and 630 shown in Fig. 6.

Fig. 7 is a schematic illustration of an alternative layout of a blank for preparing corrugated cardboard containers with reinforced corners, according to an exemplary embodiment of the invention. In an exemplary embodiment of the invention, the indentation for reinforcing the corners may be on any side of a corner depending on the position of the extension to the length of the flap that forms the adjacent wall of the container, since it is the extension piece of the flap that is folded to form an indentation before being attached to the adjacent wall. In an exemplaiy embodiment of the invention, a blank 700, illustrates a layout for forming one reinforced corner on each wall of the container. Optionally, blank

700 comprises a central generally rectangular area 710 with flaps 720 extending from the generally rectangular area. Optionally, each flap extends in length beyond the size of the generally rectangular area 710 with an extension part 750.

Optionally, when folding up blank 700 to form a container the extension part 750 is folded at fold lines 730, 740 and 745 to form an indentation to reinforce the corner as described above. In some embodiments of the invention, the walls of container 700 are of equal length, so that generally rectangular area 710 forms a generally square bottom. In some embodiments of the invention, all corners of a container are reinforced to maximize the containers durability. Alternatively, some corners are reinforced and some are not, depending on the required use of the container.

It should be appreciated that the above described methods and apparatus may be varied in many ways, including omitting or adding steps, changing the order of steps and the type of devices used. It should be appreciated that different features may be combined in different ways. In particular, not all the features shown above in a particular embodiment are necessary in every embodiment of the invention. Further combinations of the above features are also considered to be within the scope of some embodiments of the invention.

Section headings are provided for assistance in navigation and should not be considered as necessarily limiting the contents of the section.

It will be appreciated by persons skilled in the art that the present invention is not limited to what has been particularly shown and described hereinabove. Rather the scope of the present invention is defined only by the claims, which follow.

Claims

1. A reinforced corrugated cardboard container formed from a folded up corrugated cardboard blank, comprising: a bottom formed from a central generally rectangular area of the blank; four walls formed by folding upward flaps extending from the rectangular area of the blank; four corners each formed by folding over an extension piece of a folded upward flap, which extends in size beyond the rectangular area, and attaching the extension piece to the folded upward flap of an adjacent wall of said container; wherein one or more of said corners are reinforced by additionally folding the extension piece of the folded upward flap forming the corner, to form an indentation to the container wall it is attached to, such that a void is formed by the extension piece of the flap between the resulting wall and a virtual straight wall defined by the central generally rectangular area.

2. A container according to claim 1, wherein the projection of said void on the bottom forms a triangle.

3. A container according to claim 1, wherein the projection of said void on the bottom form a semi-circle.

4. A container according to claim 1, wherein the projection of said void on the bottom form a trapezoid.

5. A container according to claim 1. wherein the indentation offsets up to 20 percent of the wall with the indentation.

6. A container according to claim 1, wherein the indentation offsets up to 50 percent of the wall with the indentation.

7. A container according to claim 1, wherein the indentation position is next to the corner in the first quarter of the length of the container.

8. A container according to claim 1, wherein the cross section of the void formed by said indentation is at least twice the size of the thickness of the corrugated cardboard.

9. A container according to claim 1, wherein the projection of said void on the bottom is precut from the blank.

10. A container according to claim 1, wherein part of the cardboard forming said indentation is adhesively attached to the other wall of the corner.

1 1. A container according to claim 1, wherein the indentation is secured by a flap attached to the top of the indentation.

12. A container according to claim 10, wherein said securing flap is part of the blank.

13. A container according to claim 10, wherein said securing flap is not part of the blank.

14. A container according to claim 1, further comprising an extension to one or more flaps to form a container with double layered walls.

15. A container according to claim 1, further comprising an extension to one or more flaps to secure the indentation.

16. A Container according to claim 1, wherein all corners of the container are reinforced.

17. A container according to claim 16, wherein reinforcement of the corners is performed by one indentation to each wall of the container.

18. A container according to claim 16, wherein reinforcement of the corners is performed by two indentations to two walls of the container.

19. A container according to claim 1, wherein selected corners of the container are reinforced.

20. A container according to claim 1, wherein the length and width of the generally rectangular bottom are substantially identical.

21. A method of producing a corrugated cardboard container with reinforced corners, comprising: providing a corrugated cardboard blank with a central generally rectangular area and flaps extending from the four sides of the generally rectangular are; folding up the flaps to create wall for the container; creating corners for the container by folding over an extension piece of a folded upward flap, which extends in size beyond the rectangular area, and attaching the extension piece to the folded upward flap of an adjacent wall of said container; reinforcing the corners by additionally folding the extension piece of the folded upward flap forming the corner, to form an indentation to the container wall it is attached to, such that a void is formed by the extension piece of the flap between the resulting wall and a virtual straight wall defined by the central generally rectangular area.

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SUBSTITUTE SHEET (RULE 28]

22. A method according to claim 21, wherein said reinforcing is performed after creating the container with non-reinforced comers.

23. A method according to claim 21, wherein said reinforcing is performed by applying a force to the external side of the walls of the container.

24. A method according to claim 21, wherein said indentation also bends the flap forming the adjacent wall.