Stackable cardboard tray

Abstract

 A box of cardboard, in particular of solid cardboard, comprising a rectangular bottom panel (2) and four upright side wall panels (3a,3b,4a,4b) connected via folding lines with the bottom panel, in which at least two facing side wall panels are provided at their vertical ends with fastening strips (20,21,22) that are connected therewith and with which adjoining side wall panels are attached to each other in the corner areas, in which at least two facing side wall panels (3b,4b) merge at their horizontal upper edge in a horizontal, inwardly extending longitudinal strip (8b) connected thereto via a folding line, which longitudinal strip merges at the inner longitudinal edge in an at least downwardly extending stiffening strip (8b,9b) connected thereto via a folding line, which stiffening strip (8b,9b) is itself connected to an attaching strip (10b) that is attached to the inner surface of the side wall panel concerned, the horizontal longitudinal strip and the longitudinal strip which extends at least downwards forming part of a longitudinal sleeve.

Description

[0001] The invention relates to a stackable box that is suitable for being incorporated in a stack of corresponding boxes, as well as a blank therefor.

[0002] Cardboard boxes filled with certain kinds of vegetables or fruit are transported from the auction to distribution centres where they are combined in groups or with other boxes with other contents to stacks supported by pallets. These combinations are made in accordance with orders placed by the retailers concerned. The finished stacks are then transported by lorry to the retailers, where the boxes are removed from the pallets and are displayed or kept in storage together with the pallet.

[0003] Here use is generally made of boxes measuring 60 cm by 40 cm, for paprika's, cucumber, lettuce and so on, for example, and boxes measuring 30 cm by 40 cm for tomatoes, for example.

[0004] In a suchlike combined stack it is of the greatest importance that the boxes support each other well. During formation of the stacks, during transport and during storage the boxes can take up positions vis-á-vis one another, for example as a result of a slight shift, that the transmission of forces does not occur at the intended places and deformation of the boxes concerned takes place. These boxes are then unfit for display. There is furthermore the risk that the contents of these boxes gets damaged and is unsaleable. In addition, the existing boxes are prone to deformation as a result of horizontal forces, which causes the transmission of forces from box to box not to take place in an optimal way and further deformation to occur. These problems arise especially if boxes of various sizes are incorporated in the stack. It has been shown in particular that the boxes measuring 60 cm by 40 cm form a weak point in those stacks.

[0005] It is an object of the invention to provide a box, which is suitable for incorporating in combined stacks as above.

[0006] It is a further object of the invention to provide a cardboard box with an increased stability.

[0007] For attaining these objects the present invention provides a box of cardboard, in particular of solid cardboard, comprising a rectangular bottom panel and four upright side wall panels connected via folding lines with the bottom panel, in which at least two facing side wall panels are provided at their vertical ends with fastening strips that are connected therewith and with which adjoining side wall panels are attached to each other in the corner areas, in which at least two facing side wall panels merge at their horizontal upper edge in a horizontal, inwardly extending longitudinal strip connected thereto via a folding line, which longitudinal strip merges at the inner longitudinal edge in an at least downwardly extending stiffening strip connected thereto via a folding line, which stiffening strip is itself connected to a fastening strip that is attached to the inner surface of the side wall panel concerned, the horizontal longitudinal strip and the longitudinal strip which extends at least downwards forming part of a longitudinal sleeve.

[0008] The horizontal, inwardly extending longitudinal strip provides a stable supporting face for other boxes to be arranged on top of the box. In the case of a 60 x 40 box with horizontal longitudinal strips along the long sides, two 30 x 40 boxes could be arranged in a stable way on to that. Because the said longitudinal strip is part of a longitudinal sleeve, the middle of the longitudinal strip which serves as supporting strip is given enough support, thus preventing collapse and thus slanting of the top boxes. Because of the longitudinal sleeves, the strength vis-á-vis sidewardly exerted forces perpendicular to the side wall concerned is increased.

[0009] Preferably the longitudinal sleeve is of a height which is the order of magnitude of the width of the horizontal longitudinal strip. In the main, despite the presence of the longitudinal sleeve, sufficient receiving space is thereby realized in the box.

[0010] The longitudinal sleeves can have any suitable cross-section, for example square/rectangular, but the longitudinal sleeve preferably has a triangular cross-section. A suchlike longitudinal sleeve is simple in shape and has high shape retention.

[0011] In a preferred embodiment the fastening strip forms a wall of the longitudinal sleeve. Thus the longitudinal sleeve has a double wall thickness on the side panel side, whereby the solidity and the resistance to impact loads is enhanced.

[0012] As an alternative the fastening strip can be located outside the longitudinal sleeve, which can be advantageous when setting up the box from a blank. The fastening strip can, in that case, extend to at least the vicinity of the bottom panel, whereby both the bending and buckling strength of the side wall panel are considerably increased.

[0013] A particularly advantageous result is obtained if the longitudinal sleeves in the box according to the invention are combined with corner columns or sleeves (known per se), in such a way that the upper edges of the corner sleeves reach to at least the vicinity of the lower surface of the horizontal longitudinal strip of the longitudinal sleeves and are preferably entirely covered by the horizontal longitudinal strip. On the one hand the corner sleeves thereby provide additional support for the longitudinal sleeves, the corner sleeves are, on the other hand, protected by the horizontal longitudinal strip of the longitudinal sleeves. The cooperation longitudinal sleeves/corner sleeves gives the box according to the invention an increased resistance to warping.

[0014] Preferably, the longitudinal sleeves are cut at their longitudinal end such that they are designed to correspond to the corner sleeves so as to abut vertical surfaces of the corner sleeves. Because of this the resistance to warping is further enlarged and a box with a very high rate of shape retention is provided. The longitudinal ends of the longitudinal sleeves can thereby transmit horizontal forces to the side walls of the corner sleeves and vice versa.

[0015] In the box according to the invention longitudinal sleeves on one pair of opposing sides can be combined with common bridge strips on the other opposing sides. This can be particularly advantageous in the case of the 60 x 40 cm box, because the support surface for 30 x 40 boxes is enlarged, be it that those additional support surfaces do not have the same stability as the horizontal longitudinal strips of the longitudinal sleeves.

[0016] In the case of a 60 x 40 box the longitudinal strips extend preferably along the side wall panels having the greatest length. Two 30 x 40 boxes can be supported on this with their long sides (40 cm) facing each other.

[0017] The invention will now be described in more detail on the basis of the exemplary embodiment shown in the accompanying drawings.

Figure 1 shows a blank of an exemplary embodiment of a box according to the invention;

figure 2 shows a detail of a corner of the box according to the invention;

figure 2A shows an alternative cross-sectional shape of the longitudinal sleeves in the box according to the invention;

figure 3 shows a stack formed of boxes according to the invention.

[0018] The blank 1 of solid cardboard comprises a rectangular bottom panel 2, to which long side wall panels 3a and 3b are connected by folding lines 2a and 2b and short side wall panels 4a and 4b by folding lines 2c and 2d. The short side wall panels 4a and 4b are connected to bridge strips 14a and 14b via folding lines 13a and 13b, respectively, which bridge strips are themselves connected by folding lines at their longitudinal ends to adhesive flaps 15a, 16a and 15b, 16b, respectively. At their longitudinal ends the short side wall panels 4a and 4b are connected by folding lines to strips from which corner sleeves are shaped.

[0019] For simplicity's sake only the two lower corner sleeve strips will be considered below. The corner sleeve strips each comprise a first sleeve wall 20a, 20b, which is connected on the one hand by folding line 17a, 17b with the side wall panels 4a, 4b and connected, on the other hand, by folding line 18a, 18b with the second sleeve wall 21a, 21b, which itself is connected by folding lines 19a, 19b to the adhesive strip 20a, 20b. The second sleeve wall 21a, 21b is, as seen in the position of use, extended slightly downwardly with regard to the first sleeve wall 20a, 20b, in order to provide a line support 23 (figure 2) for the corner sleeve on the bottom panel 2.

[0020] For simplicity's sake only one of the long side wall panels will be considered, too. The long side wall panel 3b merges into the first longitudinal sleeve strip 8b by folding line 5b, which first longitudinal sleeve strip is connected by folding line 6b to the second longitudinal sleeve strip 9b, which is in turn connected to the attaching strip 10b by folding line 7b. In the material of the strips 9b and 10b incisions 12b have been made at an angle of, for instance, 45° and triangular portions 11b have been removed.

[0021] If the box according to the invention is formed from the blank of figure 1 then the corner sleeves are on the one hand formed by an upward turning movement about the folding lines 17a, b, 18a, b and 19 a, b in such a way that the first sleeve wall 20a, b is perpendicular to the short side wall panels 4a, 4b. At the position of the adhesive strips 20a, 20b adhesion takes place on the inner surface (or the top surface) of the short side wall panels 4a, 4b. On the long side wall panels 3a, 3b sleeve formation also occurs by folding about the folding lines 5b, 6b and 7b, whereby the outer edge of the attaching strip lob ends approximately at the location of the folding line 2b and the attaching strip 10b gets adhered to the top surface of the longitudinal side wall panel 3b. In doing this the first longitudinal sleeve strip 8b will be perpendicular with regard to the long side wall panel 3b. The shaded portions S of the attaching strip 10b are also adhered to the long side wall panel 3b. The second longitudinal sleeve strip 9b is allowed to retreat upwards in a slanting way from the folding line 7b because of the incisions 12b. In that way a vertical space is reserved at the ends of the formed longitudinal sleeve, which is triangular in the horizontal cross-section, in accordance with the cross-section of the corner sleeve.

[0022] When actually setting up the box the upper portions of the corner sleeves consequently fit in the cut-back ends of the longitudinal sleeves and the two corner sleeve walls 21a, 21b are provided on their lower surface, as seen in the blank of figure 1, with an adhesive and are adhered therewith to the lower surface of the attaching strip 10b, as seen in the blank of figure 1. Then the bridge strips are turned over about folding lines 13a, 13b into a horizontal position, in which they extend over the corner areas and are attached with the help of adhesive flaps 15a, b and 16a, b on the outer surface of the long side wall panels 3a, 3b.

[0023] In the finished box, as shown in figure 2 (for clarity's sake the bridge strip with adhesive flaps has been omitted in figure 2), the longitudinal sleeve and the corner sleeve interlock, as it were, and transmission of force can take place via line-shaped contact 40 between the lower surface of the first longitudinal sleeve 8b and the upper edge of the second corner sleeve wall 21b, for taking up vertical forces, and via line-shaped contact 30 between the end edge of the second longitudinal sleeve strip 9b and the inwardly facing surface of the second corner sleeve wall 21b. A high resistance towards deformation by warping is thus obtained.

[0024] The incisions 12b are made in accordance with the selected corner sleeve shape, in particular - in this example - the angle under which the wall 21a, b extends with regard to the panel 3b. The widened portions 11b prevent a portion being there which would have to be folded against the lower side of the longitudinal strip 8b.

[0025] In figure 2A an alternative construction of the side wall of the box according to the invention is shown, in which the attaching strip 10b' is turned towards the inside of the longitudinal sleeve and is adhered to the inner surface of the side wall panel 3b'. Because of this the strength of the sleeve is optimal. In this case the incisions will be also made in conformity with 12 in figure 1. Removing the portions 11b does not seem to be essential although it could be considered cutting away the portions S as well. In addition - for reasons of uniformity of wall construction (several layers) - continuing the incisions 12b in both cases according to a line (12b') perpendicular to the folding line 7b up to the end longitudinal edge of the strip 10b could be considered. The cut-away portion then has a width which corresponds to the width of the strips 20a, 20b.

[0026] In figure 3 it is shown how various sizes of boxes according to the invention can be combined. The boxes are free of projections. A box 50 measuring 60 by 40 cm is placed at the bottom and on top of that, diagonally, two boxes 60a, b of 30 cm by 40 cm are placed. The long sides of the lowest box are fitted with the longitudinal sleeves according to the invention and offer a stable support for the two smaller boxes placed above it. The outer dimensions are substantially constant in a vertical direction, which is conducive to handling and incorporating in stacks.

[0027] The small boxes of 30 cm by 40 cm are preferably also fitted on their long sides with longitudinal sleeves, in order to provide a box of 60 cm by 40 cm possibly placed above that with a stable central support.

[0028] The boxes according to the invention are suitable for garden produce, and particularly the boxes of 60 by 40 cm are possibly also suitable for fish produce.

Claims

1. A box of cardboard, in particular of solid cardboard, comprising a rectangular bottom panel and four upright side wall panels connected via folding lines with the bottom panel, in which at least two facing side wall panels are provided at their vertical ends with fastening strips that are connected therewith and with which adjoining side wall panels are attached to each other in the corner areas, in which at least two facing side wall panels merge at their horizontal upper edge in a horizontal, inwardly extending longitudinal strip connected thereto via a folding line, which longitudinal strip merges at the inner longitudinal edge in an at least downwardly extending stiffening strip connected thereto via a folding line, which stiffening strip is itself connected to an attaching strip that is attached to the inner surface of the side wall panel concerned, the horizontal longitudinal strip and the longitudinal strip which extends at least downwards forming part of a longitudinal sleeve.

2. Box according to claim 1, in which the longitudinal sleeve has a height which is in the order of magnitude of the width of the horizontal longitudinal strip.

3. Box according to claim 1 or 2, in which the longitudinal sleeve has a triangular cross section.

4. Box according to claim 1, 2 or 3, in which the fastening strip forms a wall of the longitudinal sleeve.

5. Box according to claim 1, 2 or 3, in which the fastening strip is located outside the longitudinal sleeve.

6. Box according to claim 5, in which the fastening strip extends from the longitudinal sleeve to at least in the vicinity of the bottom panel.

7. Box according to any one of the preceding claims, in which the fastening strips on the vertical ends of the side wall panels form part of the corner sleeve shaped structures, the upper edges of which reach to at least in the vicinity of the lower surface of the horizontal longitudinal strip of the longitudinal sleeves, and are preferably entirely covered by the horizontal longitudinal strip.

8. Box according to claim 7, in which the corner sleeves extend with their lower edges to near the top surface of the bottom panel.

9. Box according to claim 7 or 8, in which the longitudinal sleeves are cut at their longitudinal ends such that they are designed to correspond to the corner sleeve structures so as to abut vertical surfaces of the corner sleeve structures.

10. Box according to any one of the preceding claims, in which one pair of opposing side wall panels is provided with longitudinal sleeves and the other set of side wall panels is provided with bridge strips extending along the top edge thereof, which bridge strips are attached to the remaining part of the box by means of attaching strips connected to their longitudinal ends by folding lines.

11. Box according to any one of the preceding claims, in which the box is free of projections.

12. Box according to any one of the preceding claims, in which the bottom panel measures 60 cm by 40 cm and the longitudinal strips extend along the side wall panels having the greatest length.

13. Box according to any one of the claims 1-11, in which the bottom panel measures 30 cm by 40 cm and the longitudinal strips extend along the side wall panels having the greatest length.

14. System comprising a plurality of boxes according to claim 12 and a plurality of boxes according to claim 13.

15. Blank, evidently suitable for conversion into a box according to any one of the claims 1-13.

16. Box of solid cardboard, comprising a rectangular bottom panel and four upright side wall panels, in which the box is provided with corner sleeves and with upper longitudinal sleeves on at least two side walls opposite each other, the corner sleeves and longitudinal sleeves forming a supporting structure, corresponding to a column-beam structure.

Drawing