WO2001094218A1

WO2001094218A1 - Stackable container

Info

Publication number: WO2001094218A1
Application number: PCT/US2001/018412
Authority: WO
Inventors: Benjamin W. Quaintance
Original assignee: International Paper Co
Current assignee: International Paper Co
Priority date: 2000-06-07
Filing date: 2001-06-06
Publication date: 2001-12-13
Anticipated expiration: 2002-12-07
Also published as: AU2001265389B2; CA2413967A1; AU6538901A; AR030697A1; NZ523145A; MXPA02011989A

Abstract

A container formed from a blank to define indexing longer walls having an inward incline but a double thickness provided by a fold at the tops thereof so that the indexing projections (12) are receivable within corresponding openings in the base (2) of a corresponding stacked container. Each part of the indexing walls has an extension (16, 18) such that at each end thereof one extension (18) attaches to the outside of an end wall while the other (16) attaches to the inside of an end wall. Preferably, the extension (16) attaches to the inside of the end wall through a pair of parallel vertical folds (22) providing a support at least in part for the weight of a corresponding stacked container. Each indexing wall has a cut-out (28) associated with the opening in the base (2) to facilitate placing the extension (12) into the opening of the base (2).

Description

STACKABLE CONTAINER

RELATED APPLICATIONS The present application claims priority to U.S. Provisional application no.

60/209,786, filed June 7, 2000 and also claims priority to U.S. Provisional application no. 60/211,530, filed June 15, 2000, both of which are incorporated by reference.

FIELD OF THE INVENTION The present invention relates to improvements in and/or relating to containers cartons, blanks therefor, related packs and methods of use. The present invention relates to a pack formed from a paperboard (preferably a paperboard which is a laminate involving a fluted paperboard medium) which provides a stackable container where a top of one is indexable reproducibly into the base of another.

BACKGROUND OF THE INVENTION Flat sheets of corrugated paperboard have been used many years as the starting material in forming containers. Corrugated paperboard generally refers to a multilayer sheet material comprised of two sheets of liner bonded to a middle corrugated layer of medium. Usually, the corrugated container plant of today is located relatively close to its customer base and includes a corrugating and laminating machine to form the paperboard and thereafter, usually in-line, slitter-slotter-scoring machines and printing and packaging machines. The liner and medium paper rolls will normally come from paper mills which generally tend to be located close to their source for raw materials. One style of container is the single-piece tray type where a single piece of corrugated paperboard will be cut and scored to form a flat blank which will then be erected into a container with four sides and a bottom. Oftentimes, closure flaps will be designed into the single-piece style. Some of these designs are provided with features to allow hand setup at a using facility while others are designed for machine setup where cooperating adjoining portions are adhesively bonded to form the container. Quite commonly, these types of containers are used for holding fresh fruits and produce from packing and shipping to display at the retail level.

Usually when packing a particular product such as poultry, tomatoes, and the like there is a typical size requirement in that the container volume is sized to hold a certain amount of product. There is also a strength requirement given the weight of product packed and the stacking, shipping and handling requirements. Of course, the paperboard material provides the structural strength depending on the grade of paper used in its formation and on the design of the box. Heavier paper grades provide greater strength in stacking and bursting. The structure of the container can add greatly to its strength properties.

Typically a packed container of produce will hold a weight suitable for handling by an individual. Such containers will be generally rectangular and have a variable height dimension ranging from three to twelve inches. Further, these containers will normally be stacked for transport and storage.

Given the basic size requirement specified by the customer it is then an effort to provide the structural stacking strength with the optimum amount of corrugated paperboard. A typical well known single piece container design is one having a bottom, two side walls hinged to the bottom and at least two end walls hinged to the bottom. To form the container the walls are folded upwardly from the bottom and then connected to form the containment volume within the four walls. Variations are well known where top closure flaps are hinged to the top edges of the side walls and for stacking strength a second end wall can be hinged to the top edge of first end wall to then form a double layer of paperboard thereby enhancing the stacking strength. Additional known features used in such containers include, for example, additional panels hinged to the end wall side edges which are used to form vertical inclined corner posts and additional layers along the side walls to likewise enhance stacking strength. When even greater stacking strength is required, additional foldable panels can be added to yield three or four ply end wall variations. When providing such containers, it is an objective to provide the maximum stacking strength utilizing the least amount of material while at the same time providing all of the other features specified by the customer, such as stacking tabs, hand holds, vent holes and the like. Exemplary stackable boxes formed from blanks are described in U.S. Patent

5,860,590, the entire disclosure of which is incorporated herein by reference.

One objective of the present invention is to provide a single piece container blank which utilizes reduced material with the enhanced stackability. Another objective is to provide a container with multiple end walls utilizing less material which has the same or enhanced strength. Yet another objective is to provide a design such that the multiple upstanding stack tabs are a part of the wall construction with sufficient structure to resist "fold over" during use. These and other objects of the invention will become apparent upon reading the specification to follow in combination with the attached drawings. SUMMARY OF THE INVENTION The present invention however is directed to preferably at least a substantially lidless form capable of providing a stable stack of like containers with their loads where the weight is capable of being taken through the wall structures of such containers without any substantial passage of stress into the load of the containers themselves.

A pack form in accordance with the present invention is useful for heavy produce, including, for example, processed poultry.

In a first aspect the present invention consists in a container formed from a blank, said container having a rectangular base, a flap sequence of two flaps (hereafter the "indexing wall flaps") from each of two opposing sides of said base, a first flap being hingedly connected to the base by a fold line, and the second flap being hingedly connected to the first flap by a fold line preferably through bridge like regions. Each indexing wall flap of each flap sequence has at least one indexing extension extending, when the box is constructed, beyond the support members of the indexing sides. In a preferred embodiment the top-most portion of the indexing extension is at a fold-line or fold-lines (preferably one only) substantially parallel to the folding line connecting the base to the indexing wall first flap. An extension flap hingedly connected to the exterior indexing wall flap is sized and positioned to fit between two flaps of the non-indexing wall. The base includes a plurality of openings inwardly and outwardly of the fold line connecting the exterior indexing wall flaps, wherein each opening receives a projecting indexing extension from a box underneath in at least the portion of the openings that is formed in the base of the box.

When the blank is erected to a walled form with the indexing walls, a plurality of upwardly directed indexing extensions or projections (preferably formed from said bridge like regions of the blank) are indexable in through the openings of the base of a like erected container. The indexing walls are inclined inwardly slightly. The opening adapted to accept the indexing extension extends to the exterior indexing wall flap, forming thereon a groove and a flap which assist in guiding an indexing extension tab into position. In a further aspect the present invention consists in a blank suitable for construction and/or erection to provide a container as previously set forth. In still a further aspect the present invention consists in as a stack a plurality of containers as previously set forth.

In yet a further aspect the present invention consists in adjacent stacks as previously set forth where the inwardly inclined indexing walls are adjacent one to another thereby providing a wedge shape gap which facilitates for cooling, and/or for other purposes, the movement of air. In yet a further aspect the present invention consists in the use of a container in accordance with the present invention.

BRIEF DESCRIPTION OF DRAWINGS Preferred forms of the present invention will now be described with reference to the accompanying drawings.

Figure 1 is a view of a preferred blank in accordance with the present invention. Figures 2 to 4 are views of blanks in accordance with the present invention. Figure 5 is a view of two stacked boxes of the present invention, wherein the inner indexing wall flap is only partially shown so that the relationship between the opening slot and the indexing extension tab can be shown.

Figure 6 is a view of an embodiment of a indexable slot wherein the tab from the exterior indexing tab wall is cut so that the depending tab includes a portion of the base, so that the tab extends below the base when the container is erected.

DETAILED DESCRIPTION OF THE INVENTION The invention includes a container formed from a blank. The container has a rectangular base, a flap sequence of two flaps (hereafter the "indexing wall flaps") from each of two opposing sides of said base. The first flap, also called the exterior indexing wall flap, is hingedly connected to the base by a fold line, and the second flap, also called the interior indexing wall flap, is hingedly connected to the first flap by a fold line, preferably through bridge like regions. Each indexing wall flap of each flap sequence has at least one indexing extension extending, when the box is constructed, beyond the support members of the indexing sides. In a preferred embodiment the top-most portion of the indexing extension is at a fold-line or fold-lines (preferably one only) substantially parallel to the folding line connecting the base to the indexing wall first flap. An extension flap hingedly connected to the exterior indexing wall flap is sized and positioned to fit between two flaps of the non-indexing wall. The base includes inwardly and outwardly of the fold line connecting the exterior indexing wall flaps a plurality of openings, wherein each receives a projecting indexing extension from a box underneath in the portion of the openings that is formed in the base of the box. When the blank is erected to a walled form with the indexing walls a plurality of upwardly directed indexing extensions or projections (preferably formed from the bridge like regions of the blank) are indexable in through the openings of the base of a like erected container. The indexing walls are inclined inwardly slightly. The opening adapted to accept the indexing extension extends to the exterior indexing wall flap, forming thereon a groove and a flap which assist in guiding an indexing extension tab into position.

The base forms a parallelogram, preferably a rectangle.

In some less preferred forms "rectangular" may approach or be "square". Preferably the blank is of a laminate which includes a flute-providing medium and the flute direction is such that the flutes extend substantially vertically in said indexing walls.

Preferably the extensions of each of the second flap of an indexing wall flap sequence folds inwardly and are secured adjacent to or inwardly of a non indexing wall flap, and provides with part of the flap thereof (preferably between substantially parallel fold lines) a gusset or other support feature at the corner.

Preferably each non indexing wall is provided with a recess from the upper extremity thereof to facilitate air flow therethrough and to facilitate unstacking and carrying of the containers. Preferably the angling in of the indexing walls is such as to provide a top to top distance between the indexing walls that is of the order of about 8 mm less than that between the fold lines of the first flap of the flap sequences from said base. For example preferably an angle of the order of 2 degrees is provided where the spacing between the fold lines from the base of said indexing wall flap sequences is of the order of 396 mm. Figure 1 shows the blank form of the present invention with the base 2 being provided with a plurality of openings 4. Foldably attached to the base 2 along fold line 8 are exterior indexing wall flaps 6. Foldably attached to the exterior indexing wall flaps 6 are interior indexing wall flaps 10. Between the exterior indexing wall flaps 6 and the interior indexing wall flaps 10 are indexing extensions 12 that preferably comprise two layers corresponding to the interior and exterior indexing walls that are joined at the fold lines 14. Any mechanical equivalent to a bridge form projection can if desired be employed (e.g., pop-ups from a fold line) but these will offer less certainty in indexing. Such a form has reduced adhesion, usefulness and overall strength.

Each of the flaps 6 includes an extension flap 18 while each of the flaps 10 includes an extension 16. The extensions 18 are connected by a fold line 20 to the first flaps 6 while the extensions 16 are connected, preferably, by between two and four fold lines 22 so as to provide a gusset form feature.50 best seen in one selected corner of a box shown in Figure 5, or other supporting structure such as a rectangular or triangular pillar. Where however the paired fold lines 22 are not provided a single fold line 22 can instead be provided substantially aligned with the fold line 20. The fold lines of such extensions are angled as required relative to the base axes.

The interior indexing flap 10 has a plurality, preferably between 3 and 5, connecting tabs 24 that, when the box is constructed, lockably engage slots 26 in base 2. There are

5 preferably small cuts 27 extending from slots 26 that can bend down when the indexing wall flap 10 is being folded in position, thereby allowing the connecting tabs 24 to more easily enter the slots 26 and providing a positive locking mechanism when the connecting tabs are in place. That is, these cuts 27 define a small tab that may be pushed down when the connecting tabs 24 pass along them to the slots 26, and partially rebound back toward

10 the original position once the connecting tabs 24 are in the slots 26.

The curvilinear cut-outs 28 extend asymmetrically on both sides of the fold lines 8. There are a plurality of cut-outs 28, corresponding in number and position to indexing extensions 12. There are preferably from two to ten, more preferably from four to six, matched sets of indexing extensions 12 and cut-outs 28 per box. The cut-outs 28 preferably

15 are bounded by a flap 30 in the base 2 adjacent to the cutout 28, defined on one side by a cut 32, which provides flexibility and positive locking when an indexing extension 12 from another box enters the cut-out 28. It is preferred that the cut-out 28 be sized and positioned so that an indexing extension 12 can fit snugly into the cut-out 28. That is, the base of the indexing extension 12 has approximately the same width and length as the portion of the

20 cut-out 28 that is removed from the base 2.

While the cut-outs 28 can be formed from intersecting straight lines, such as is shown in cut-out 28 in Figures 2 and 4, it is preferred that the cut-out boundary be formed from straight non-intersecting lines and a curvilinear shape.

It is preferred that the slots 28 typically have rounded ends. In comparison, the slots

25 26 have oval ends.

It is even more preferred that the cut-out 28 from the exterior indexing wall 6 be formed from three intersecting arcs, that is, two smaller radius arcs that begin the cut-out and a larger radius arc that forms the tab. For example, a straight line or curvilinear line extending from the base 2 toward the interior indexing wall 10, that becomes a small radius,

30 i.e., between about 0.05 inches to about 1 inch, preferably from about 0.1 inches to about 0.5 inches, curve to turn back more than 90 degrees, say, for example, between about 100 degrees and about 150 degrees, such that the line is now traveling in a direction toward the base 2. The cut-out line then enters a larger radius curve, i.e., between about 0.8 inches to about 4 inches, preferably between about 1 inch to about 2 inches, that curves the cut back

35 away from the base and forms a depending tab 46. Finally, another small radius curve curves the cut back toward the base. The large radius depending portion 46 and small radius portion returning the depending portion to the vertical sides of the cut-out 28 may be connected by additional straight-line segments as needed. The intersection of straight cut lines cause difficulty with cutting apparatus. Also, such an arrangement results in a tab formed by the larger radius curve that has no sharp point that may be easily bent over or snagged on another box during handling. In a particularly advantageous form of the invention shown in Figure 6, the larger radius curve which makes up the depending tab(s) 46 extends beyond fold line 8, for example, approximately one-eighth to three thirty-secondths of an inch when the blank is flat (see partial detail view, Figure la ). Thus the tab 46 extends slightly below the lowermost (under) surface of base 2 when the container is fully erected. This extension facilitates "blind" positioning of one container with respect to another immediately below it as the containers are being stacked by causing the extension to engage an indexing extension 12.

It is preferred that the indexing extensions 12 be formed from mirror image bridging sections, and furthermore that the bridging sections have sides 13 that are angled with respect to the top of the box, preferably between about 2 degrees and 20 degrees off of perpendicular, such that the portion of the indexing extensions 12 have a narrower profile at the top, that is, the portion first inserted into the cut-outs 28 of another box, of the indexing extensions to facilitate placing the indexing extensions 12 into the slots 28. To that end, the sides of slots 28 are preferably complementarily sloped away from perpendicular.

Each slot is sized to accept the tab extending into the slot. Preferably, corners of slots that are not adjacent to locking tabs are formed by arcs of small radius, for example between 0.1 and 0.5 inches in radius.

The non-indexing exterior wall flaps 34 are foldably attached to the base 2 at fold line 36. The non-indexing interior wall flaps 38 are foldably attached to the non-indexing interior wall flaps 24 at fold lines 40. While fold lines 40 can be a single fold line, it is preferred that the fold lines 40 be a plurality, preferably 2, of closely spaced parallel fold lines. The non-indexing interior wall flaps 38 have tab 42 sized and positioned to engage slot 44 in the base 2 when the box is constructed. Preferably, a tab 43 is sized and positioned on extension flap 18 so that the tab 43 also engages slot 44 in base 2 when the box is constructed.

Preferably said non indexing wall flaps are vertical from the base in a constructed box. The flap 18 is advantageously sized to fit between the non-indexing exterior wall flaps 34 and the non-indexing interior wall flaps 24, and also between the fold line36 and the fold lines 40. The erecting arrangement is such that the flaps 18 are each sandwiched by the non-indexing exterior wall flaps 34 and the non-indexing interior wall flaps 38. The base of the box is advantageously between about 12 inches and about 36 inches, preferably between about 20 inches and about 28 inches, in length, and between about 10 inches and about 24 inches, preferably between about 12 inches and about 20 inches, in width. The height of the box when assembled, excluding the indexing extensions 12, is between about 2 inches and about 8 inches, preferably between about 3 inches and about 5 inches. The indexing extensions 12 have a height of between about 0.24 inches and about 2 inches, preferably between about 0.5 inches and about 1 inch, extending above the top of the box.

The connecting tabs 24 are of a height sufficient to engage the slots 26, for example between about 0.2 and 0.5 inches in height. There are preferably between about 4 to about 24 holes 4 in the base 2 of the box.

Each hole should be of sufficient size that the material intended to be in the box, i.e., processed chicken or other produce, will not pass through the holes 4. Like other cut-outs, it is preferred that the holes be formed of curvilinear lines such as short radius arcs optionally joined by straight-line segments. There is advantageously a gap between the top of the non-indexing wall defined by the fold lines 40 and the next box. Finally, there is advantageously circular or semicircular holes on the indexing walls. These holes provide needed ventilation for temperature control. In one embodiment, the hole on the non-indexing walls extends for the entire length of the walls. Placing these holes at the top of both the indexing and non-indexing walls allows for easier manipulation of a stack of boxes.

The indexing walls are angled inward so that the top of the indexing extension 12 fits into the slot 28 cut into the base 2. The flap that is formed in slot 28 by the three aforementioned intersecting arcs provides flexibility to guide the indexing extension 12 from a lower box into the slot 28. The box can be constructed without adhesive. The optional gusset assembly formed by the extending flaps 16 may be held in place by being sandwiched between the non- indexing wall flaps 18, 34 and 38, and/or also may have a tab that engages slot 44, or it may remain in place by abutting interior non-indexing wall flap 38.

Figure 1 shows the embodiment of the invention wherein the flap 46 is formed by three intersecting arcs joining side cuts that are between about 1 and 20 degrees from perpendicular to the fold line 8. Figure 2 shows an embodiment wherein the tab 46 is formed by one continuous arc. Figure 3 shows an embodiment wherein the arc forming the slot 28 in the exterior indexing wall is in the shape of a semicircle, where the edge of the circle rather than the tab 46 guides the incoming indexing extension 12. Figure 4 shows an embodiment wherein the tab 46 is triangular in shape.

In the arrangement as depicted the structure is such that in the flute running direction the width of a preferred container is about 16 inches from fold line 8 to fold line 8. The tops of the indexing extensions 12 are approximately 8 mm closer together than they would be if the indexing walls were vertical from the base. In an erected carton as depicted in Figure 5 the box has an advantage of strength owing to the construction, the stacking strength coming from the indexing of wall to wall using the male protuberances 12.

The tabs formed adjacent to the slots, i.e., to the indexing slots 28, provide positive locking that fits with the male member, i.e. the indexing extensions 12. It is preferred that the longer opposing walls be the indexing walls.

In addition where a support structure is provided such as a gusset is formed in a corner there is additional strengthening owing to greater resistance to racking forces as well as more vertical structural support. Nevertheless even in the forms without the corner feature a container of acceptable strength is provided. This is because the various relief features and openings substantially as shown allows a throughput of air through a container above its produce or other load and under the base of a stacked on top container while additional airflows are possible around the stack owing to the fact that the indexing walls are inclined slightly.

While the type of produce placed within the container is not a part of the invention, the presently disclosed embodiment is particularly useful for packaging foodstuffs including processed poultry or vegetables. The embodiment depicted is for manual setup in the field when ready for use. This is opposed to machine setup where automated equipment will fold and join container parts (usually with adhesives) into a permanent box form. Once formed into the open container fresh fruits, produce, or any other product can be placed within the walls of the box. After use, a container can readily be returned to its flat form for recycling. Typically, although not essential for the present invention the blank material is corrugated paperboard where a corrugated medium layer has liner sheets bonded thereto forming the three layer flat paperboard blank. In order to provide the stacking strength the corrugations run from top to bottom as will be well understood by those with ordinary skill in the art. A preferred material from which such a container can be made is a dual arch (2 xl60 grams per square meter) semi chemical pulp paper corrugated board with outside lines of 290 grams per square meter kraft.

Persons skilled in the art will appreciate the alternatives that a structure in the accordance with the present invention provides.

Claims

THE CLAIMS What is claimed is:

1. A container formed from a blank, said container comprising: a parallelogram base having four sides; an indexing flap sequence of two indexing wall flaps extending from first opposed sides of said rectangular base comprising an exterior indexing wall flap hingedly connected to the base by a first fold line; an interior indexing wall flap hingedly connected to the first flap by a second fold line, wherein the second fold line is interrupted by at least one cut-out and has at least two bridging areas defining at least two indexing extensions; and at least two indexing slots each positioned in space relation along the first fold line, wherein each slot is sized and positioned to receive the indexing extensions from a subjacent erected container in a stacking configuration, and the slot is cut from a portion of the base and a portion of the exterior indexing wall flap, with the cut portion of at least the exterior indexing wall forming a structure that assists in guiding an indexing extension of the subjacent container into the indexing slot, and wherein each indexing flap sequence forms an indexing wall.

2. The container of claim 1 wherein the base forms a rectangle, and further comprising a non-indexing flap sequence of two non-indexing wall flaps extending from second opposing sides of said rectangular base comprising an exterior non-indexing wall flap hingedly connected to the base by a third fold line, and an interior non-indexing wall flap hingedly connected to the first non- indexing wall flap by a fourth fold line, wherein in each flap sequence the distance between the third fold line and the fourth fold line is less than the distance between the first fold line and the second fold line, wherein each non-indexing flap sequence forms a non-indexing wall having at least two indexing slots and at least two indexing extensions.

3. The container of claim 1 wherein the indexing slot comprises first and second side cuts extending distally away from the first fold line on each side of the slot and a joining cut connecting the distal ends of each side cut.

4. The container of claim 3 wherein the joining cut is an arcuate cut.

5. The container of claim 4 wherein the arcuate cut extends from each side cut toward the first folding line.

6. The container of claim 3 wherein the first and second side cuts of an indexing slot are substantially perpendicular to the first fold line and are joined by an arcuate cut that extends from each side cut toward the first folding line.

7. The container of claim 3 wherein the joining cut comprises a convex arcuate cut joined on each end to the side cuts by concave arcuate cuts.

8. The container of claim 7 wherein the convex arcuate cut has a radius greater than the radius of each of the two concave arcuate cuts.

9. The container of claim 1 wherein the joining cut extends from the distal end of each side cut toward the first folding line.

10. The container of claim 1 wherein the interior indexing wall flap further comprises at least one protrusion distal from the second fold line, and wherein the base further comprises a connecting slot sized and positioned to accept the protrusion.

11. The container of claim 1 wherein the base further comprises a plurality of vent holes and each indexing wall comprises vent holes in the form of a semi-circle or semi-oval shape extending from an upper extremity thereof to facilitate air flow therethrough.

12. The container of claim 1 further comprising at least one support member in at least one corner.

13. The container of claim 1 wherein the support member is a gusset formed from gusset flaps hingedly connected to the interior indexing wall flap by a fifth fold line, said gusset flaps comprising at least one additional fold line, so that when erected, in at least one corner of the erected container, the gusset flaps on each of the second indexing wall flaps fold inwardly to define a gusset configuration, and said gusset flaps being sized to be sandwiched between the third and the fourth fold lines and between the interior non- indexing wall flap and the exterior non-indexing wall flap, and when additional erected containers are stacked, each wall of the longer sides of the base is indexed into a superimposed base and each superimposed base, under load, is in part supported at said gusset configuration. 5

14. The container of claim 1 wherein the blank is a laminate including a flute providing medium having a flute direction such that the flutes extend substantially vertically in said indexing walls.

10 15. The container of claim 1 further comprising bendable tabs extending from the indexable slot in the base, wherein the tab forms a positive locking action when an indexing extension is placed in the indexing slot.

16. The container of claim 1 wherein the cut portion of the exterior indexing wall and 15 the base form a structure that assists in guiding an indexing extension of the subjacent container into the indexing slot, and wherein the structure extends below the bottom of the base when the container is erected.

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