CARDBOARD TRAY

Abstract

 The invention relates to a Cardboard tray folded from an unfolded sheet of cardboard, which tray comprises:
- a bottom wall with a circumferential edge composed out of an even number of straight edges;
- wall parts each arranged to a straight edge of the bottom wall;
- first and second flange parts alternately arranged to subsequent wall parts along the circumferential edge of the wall parts, which flange parts are arranged along a folding line to an edge of said wall part opposite of, and preferably parallel to, the respective straight edge of the bottom wall;
wherein the first flange parts comprise at least a first and a second elongate flange part section, which are connected parallel and along an elongate edge to each other;
wherein the first elongate flange part section is arranged to the respective wall part and wherein the second flange part section is double folded against the first flange part section;
wherein the first flange parts further comprise a third elongate flange part section, which third elongate flange part section is connected parallel and along an elongate edge to the second elongate flange part section and wherein the third elongate flange part section is adhered to the outside of the respective wall part;
wherein each first flange part section has opposite first side edges, extending between the folding line and the elongate edge along which the second flange part section is connected to the first flange part section;
wherein each second flange part has an elongate edge, opposite and substantially parallel to the folding line, and opposite second side edges, extending between the elongate edge and the folding line;
wherein the first flange part sections and the second flange parts form a circumferential flange;
wherein at the transition from a first flange part section to a second flange part, along the circumferential flange, the respective first side edge neighboring the respective second side edge is askew with the folding line of the second flange part and / or said second side edge is askew with the folding line of the first flange part section.

Description

[0001] The invention relates to a cardboard tray folded from an unfolded sheet of cardboard, which tray comprises:

• a bottom wall with a circumferential edge composed out of an even number of straight edges;
• wall parts each arranged to a straight edge of the bottom wall;
• first and second flange parts alternately arranged to subsequent wall parts along the circumferential edge of the wall parts, which flange parts are arranged along a folding line to an edge of said wall part opposite of, and preferably parallel to, the respective straight edge of the bottom wall.

[0002] Such cardboard trays are known from EP 2441697. In this publication, the walls of the tray are kept together by skinning a foil to the inside of the walls and the bottom. This skinning foil also extends over the flange parts to keep the flanges together and form a circumferential flange.

[0003] Such a cardboard tray skinned with foil can be provided with a top seal foil to close the tray airtight. However, for some applications, such as packaging fruit and vegetables in the cardboard tray, the tray should be able to be vented. Providing air holes in a skinned cardboard tray is possible, but the costs are too high to provide holes after skinning the cardboard tray.

[0004] It is also possible to fold a cardboard tray from an unfolded sheet and have wall parts glued together by glue flaps arranged to the wall parts. If a top seal is provided onto the flange parts, then the sealed trays can no longer be stacked as the flange parts will fold upwards if the top seal foil is subjected to the weight of another tray. This will make a stack of such folded trays unstable.

[0005] Another disadvantage is that when the top seal tool closes too quickly, the flange parts could get double folded between the tool parts, making the sealed tray unusable.

[0006] First flange parts could be strengthened by providing a first, second and third flange part section, which are double folded and wherein the third flange part section is adhered on the outside of the respective wall part.

[0007] When a foil is sealed to said strengthened flanges, the foil will be more tight as the strengthened flanges will resist folding up, when the foil is subjected to weight. However, the second flange parts could not be strengthened and will still fold up.

[0008] The unpublished application no. PCT/EP2019/056684 of the proprietor suggests to adhere the first flange parts to the second flange parts, which provides some additional strength to the second flange parts. However, the adhering of the flange parts requires some additional time at the moment of sealing the top foil. This additional time is of disadvantage, especially at high speed manufacturing lines.

[0009] Accordingly, it is an object of the invention to reduce the above mentioned disadvantages.

[0010] This object is achieved according to the invention with a cardboard tray according to the preamble, which is characterized in that the first flange parts comprise at least a first and a second elongate flange part section, which are connected parallel and along an elongate edge to each other;
wherein the first elongate flange part section is arranged to the respective wall part and wherein the second flange part section is double folded against the first flange part section;
wherein the first flange parts further comprise a third elongate flange part section, which third elongate flange part section is connected parallel and along an elongate edge to the second elongate flange part section and wherein the third elongate flange part section is adhered to the outside of the respective wall part;
wherein each first flange part section has opposite first side edges, extending between the folding line and the elongate edge along which the second flange part section is connected to the first flange part section;
wherein each second flange part has an elongate edge, opposite and substantially parallel to the folding line, and opposite second side edges, extending between the elongate edge and the folding line;
wherein the first flange part sections and the second flange parts form a circumferential flange;
wherein at the transition from a first flange part section to a second flange part, along the circumferential flange, the respective first side edge neighboring the respective second side edge is askew with the folding line of the second flange part and / or said second side edge is askew with the folding line of the first flange part section.

[0011] With the cardboard tray according to the invention, the first flange parts are strengthened by the double folded first, second and third elongate flange part sections of which the third flange part section is adhered to the respective wall part. By having further the side edge of at least one flange part at a transition askew from the folding line of the other flange part, it is ensured that after sealing a foil to the circumferential flange, the second flange part cannot be folded up or down. Due to the askew side the top sealed foil will keep the second flange part connected to the first flange part and prevent that the second flange part can be folded.

[0012] There is no need to have an addition step to adhere the first flange parts to the second flange parts as is required in the unpublished application no. PCT/EP2019/056684, such that no delay is generated when sealing the top foil to the circumferential flange.

[0013] In an embodiment of the cardboard tray according to the invention the second flange part section extends in longitudinal direction on both ends beyond the first flange part section and overlaps with the adjacent second flange parts along the circumferential edge.

[0014] Due to the overlap of the second flange part section with the second flange part, the first flange part and second flange part can be adhered together to provide additional strength in addition to the strength provided by the askew sides and top seal foil.

[0015] In a preferred embodiment of the cardboard tray according to the invention the first side edges are under an angle between 40° and 60°, preferably 45°, with the folding line of the neighboring second flange part and / or the second side edges are under an angle between 40° and 60°, preferably 45°, with the folding line of the neighboring first flange part section.

[0016] With the preferred angle of 45° an optimal addition in strength is provided to the circumferential flange when a foil is sealed thereto.

[0017] In yet another embodiment of the cardboard tray according to the invention the first side edges and / or second side edges are curved, for example J-shaped.

[0018] Having the askew side edges curved, the contributed strength to the circumferential edge can be further optimized depending on the application of the cardboard tray and the weight the top seal foil needs to bear.

[0019] In a further preferred embodiment of the cardboard tray according to the invention the second flange part extends in longitudinal direction on both ends underneath at least the first flange part section of the first flange part.

[0020] In this embodiment the second flange parts can be snapped under the at least first flange part sections of the first flange part. This ensures that the second flange part is already in the horizontal position when the foil is sealed to the circumferential flange and avoids that the second flange part is double folded to a too quick closing of the top seal tool.

[0021] Another advantage is that after peeling the top seal foil from the cardboard tray, both the first and second flange parts remain in position as the second flange parts are snapped under the first flange parts.

[0022] In yet another embodiment of the cardboard tray according to the invention the second flange part extends in longitudinal direction on both ends underneath the second flange part section of the first flange part.

[0023] Having the second flange part extending underneath also the second flange part provides for a more solid connection with the first flange part, as two layers of cardboard provide a support for the second flange part.

[0024] Preferably, the cardboard tray according to the invention further comprising a top seal foil sealed to the circumferential flange.

[0025] In a method according to the invention, the cardboard tray, having the first flange parts folded and with the third flange part section adhered to the respective walls, is guided along a guide track with the second flange parts parallel to the transport direction. During the movement of the cardboard tray in transport direction, the second flange part is folded, for example by a roller, which is brought in contact with the second flange part.

[0026] Preferably, the guide track supports the walls corresponding to the second flange parts. This ensures that the wall parts supported by the guide track cannot bulge, which would hinder folding of the second flange part.

[0027] For embodiments having the second flange parts snapped under the first flange part, the roller could have a cam surface, such that the roller folds the second flange part and then pushes the second flange part underneath the first flange part. It will be clear that other mechanisms for snapping the second flange part underneath the first flange part are also within the scope of the present invention.

[0028] These and other features of the invention are elucidated in conjunction with the accompanying drawings.

Figure 1 shows a top view of an unfolded sheet for a first embodiment of a cardboard tray according to the invention.

Figure 2 shows a perspective view of the sheet according to figure 1 almost completely folded to a cardboard tray, seen from above.

Figure 3 shows a top view of an unfolded sheet for a second embodiment of a cardboard tray according to the invention.

Figure 4 shows a perspective view of the sheet according to figure 3 almost completely folded to a cardboard tray, seen from above.

Figure 5 shows a top view of an unfolded sheet for a third embodiment of a cardboard tray according to the invention.

Figure 6 shows a perspective view of the sheet according to figure 5 almost completely folded to a cardboard tray, seen from below.

Figure 7 shows a top view of an unfolded sheet for a fourth embodiment of a cardboard tray according to the invention.

Figure 8 shows a perspective view of the sheet according to figure 7 almost completely folded to a cardboard tray, seen from below.

Figure 9 shows a top view of an unfolded sheet for a fifth embodiment of a cardboard tray according to the invention.

Figure 10 shows a perspective view of the sheet according to figure 9 almost completely folded to a cardboard tray, seen from below.

[0029] Figure 1 shows an unfolded sheet 1 for a first embodiment of a cardboard tray according to the invention. The unfolded sheet 1 has a bottom wall 2 with straight edges 3. Wall parts 4, 5 are arranged to the straight edges 3. The wall parts 4 are provided with glue flaps 6, which are in folded shape adhered to the wall parts 5.

[0030] First flange parts 7, 8, 9 and second flange parts 10 are arranged to the wall parts 4, 5 respectively.

[0031] Figure 2 shows the sheet 1 almost completely folded into a cardboard tray. The first flange part section 7 is horizontal, the second flange part section 8 is folded to the underside of the first flange part section 7 and the third flange part section 9 is adhered to the wall 4.

[0032] The second flange part section 8 has a part extending on both ends past the first flange part section 7, such that it can support the second flange part 10 and preferably be adhered to each other.

[0033] The side edge 11 of the first flange part section is askew with the folding line 13 of the second flange part 10, while the side edge 12 of the second flange part is askew with the folding line 14 of the first flange part 7, 8, 9. The side edges 11, 12 at the transition from the first flange part section 7 to the second flange part 10 make an angle α with the folding line 14 and is preferably 45°.

[0034] When the sheet 1 is fully folded to a cardboard tray and the glue flaps 6 are adhered to the walls 5, the tray can be filled and a foil can be sealed to the circumferential flange 7, 10.

[0035] Figure 3 shows an unfolded sheet 20 for a second embodiment of a cardboard tray according to the invention. The sheet 20 is similar to the unfolded sheet 1 of figure 1 and corresponding parts are provided with the same reference signs.

[0036] First flange parts 21, 22, 23 and second flange parts 24 are arranged to the wall parts 4, 5 respectively. The first flange part section 21 has curved side edges 25, which are similar to a J-shape. The second flange part section 22 has an equally shaped side edge 26. The side edge 24 of the second flange part 24 is correspondingly shaped and as a result both side edges 25, 26, 27 are askew with the folding lines 28, 29 of the first flange part and second flange part respectively.

[0037] Figure 4 shows the sheet 20 almost completely folded into a second embodiment of a cardboard tray. The side edges 25 and 27 at a transition from a first flange part 21, 22, 23 to a second flange part 24 are arranged against each other. When a foil is sealed to the flange parts 21, 22, 23, 24, the J-shape will ensure that the second flange part 24 is firmly secured to the first flange part 21, 22, 23.

[0038] Figure 5 shows an unfolded sheet 30 for a third embodiment of a cardboard tray according to the invention. The sheet 30 is similar to the unfolded sheet 1 of figure 1 and corresponding parts are provided with the same reference signs.

[0039] A first flange part consisting of the first flange part section 31, second flange part section 32, and third flange part section 33 is arranged to the wall parts 4, while a second flange part 34 is arranged to the wall parts 5.

[0040] The ends of the first flange part section 31 extend over the ends of the second flange part section 32 in folded position as shown in figure 6. The third flange part section 33 is adhered to the wall part 4.

[0041] The ends 35 extend underneath the ends of the first flange part section 31, such that the second flange part 34 can snap under the first flange part section 31. Due to the extension of the ends 35, the side edges of the second flange part 34 are not in line with the folding line 36 of the first flange part 31, 32, 33, such that the side edges 35 are askew with the folding line 36.

[0042] Figure 7 shows an unfolded sheet 40 for a fourth embodiment of a cardboard tray according to the invention. The sheet 40 is similar to the unfolded sheet 30 of figure 6 and corresponding parts are provided with the same reference signs.

[0043] The difference between sheet 40 and sheet 30 is the shape of the second flange part section 41 and the second flange part 42.

[0044] The second flange part section 41 is provided with semi-circular shaped cut out at the side edges 43. The second flange part 42 is provided with semi-circular shaped protrusions at the side edges 44, which interconnect with the semi-circular shaped cut outs 43 in fully folded position.

[0045] As shown in figure 8, the side edges 44 of the second flange part 42 extend under the first flange part section 31. Due to the semi-circular shape of the side edges 44 of the second flange part 42, the side edges 44 are askew with the folding line 36.

[0046] An advantage of the semi-circular shape of the side edges 44 is that the second flange parts snap more easily underneath the first flange parts.

[0047] Figure 9 shows an unfolded sheet 50 for a fifth embodiment of a cardboard tray according to the invention.

[0048] The unfolded sheet 50 has a bottom wall 51 and wall parts 53, 54 along the straight edges 52 of the bottom wall 51. Double folding mounting flaps 55, 56 are arranged between each pair of wall part 53 and wall part 54.

[0049] A first flange part consisting out of a first flange part section 57, a second flange part section 58 and a third flange part section 59 are arranged to the wall parts 53, while a second flange part 60 is arranged to the wall parts 54.

[0050] The second flange part section 58 is provided with hook shaped ends 61, which will hook around the adjacent wall part 54 to keep the wall parts 53, 54 together and will support the ends of the second flange part 60.

[0051] The unfolded sheet 50 is laminated with a foil 62, which extends over the bottom wall 51, the wall parts 53, 54, the mounting flaps 55, 56, the first flange part section 57 and the second flange part 60. This foil 62 provides for an airtight sealing of the cardboard tray when fully folded. The mounting flaps 55, 56 can be folded against a wall part 54 and the hook shaped ends 61 will relieve the foil 62 from some tension at the transition from the first flange part 57, 58, 59 to the second flange part 60. The hook shaped ends 61 will also guide the folding of the foil 62, when the unfolded sheet 50 is folded into a cardboard tray.

Claims

1. Cardboard tray folded from an unfolded sheet of cardboard, which tray comprises:

- a bottom wall with a circumferential edge composed out of an even number of straight edges;

- wall parts each arranged to a straight edge of the bottom wall;

- first and second flange parts alternately arranged to subsequent wall parts along the circumferential edge of the wall parts, which flange parts are arranged along a folding line to an edge of said wall part opposite of, and preferably parallel to, the respective straight edge of the bottom wall;

characterized in that
the first flange parts comprise at least a first and a second elongate flange part section, which are connected parallel and along an elongate edge to each other;
wherein the first elongate flange part section is arranged to the respective wall part and wherein the second flange part section is double folded against the first flange part section;
wherein the first flange parts further comprise a third elongate flange part section, which third elongate flange part section is connected parallel and along an elongate edge to the second elongate flange part section and wherein the third elongate flange part section is adhered to the outside of the respective wall part;
wherein each first flange part section has opposite first side edges, extending between the folding line and the elongate edge along which the second flange part section is connected to the first flange part section;
wherein each second flange part has an elongate edge, opposite and substantially parallel to the folding line, and opposite second side edges, extending between the elongate edge and the folding line;
wherein the first flange part sections and the second flange parts form a circumferential flange;
wherein at the transition from a first flange part section to a second flange part, along the circumferential flange, the respective first side edge neighboring the respective second side edge is askew with the folding line of the second flange part and / or said second side edge is askew with the folding line of the first flange part section.

2. Cardboard tray according to claim 1, wherein the second flange part section extends in longitudinal direction on both ends beyond the first flange part section and overlaps with the adjacent second flange parts along the circumferential edge.

3. Cardboard tray according to claim 1 or 2, wherein the first side edges are under an angle between 40° and 60°, preferably 45°, with the folding line of the neighboring second flange part and / or the second side edges are under an angle between 40° and 60°, preferably 45°, with the folding line of the neighboring first flange part section.

4. Cardboard tray according to any of the preceding claims, wherein the first side edges and / or second side edges are curved, for example J-shaped.

5. Cardboard tray according to claim 1, wherein the second flange part extends in longitudinal direction on both ends underneath at least the first flange part section of the first flange part.

6. Cardboard tray according to claim 5, wherein the second flange part extends in longitudinal direction on both ends underneath the second flange part section of the first flange part.

7. Cardboard tray according to any of the preceding claims, further comprising a top seal foil sealed to the circumferential flange.

Drawing