Method Of Producing A Packaging Container, A Packaging Container And A Curling Tool

Abstract

The present disclosure relates to a method of forming a paperboard packaging container from a rectangular body blank, the method comprising the steps of providing a rectangular body blank having a first end edge and a second side edge, forming a tubular container body from the rectangular body blank, sealing together the first and the second side edge of the body blank, closing the first end opening by pressing a paperboard disc into the first end opening, pressing the first end of the tubular container body into a curl forming portion of a curling tool, filling the packaging container with bulk solids, and closing the second end opening.

Claims

1. A method of forming a paperboard packaging container from a rectangular body blank, the method comprising the steps of; a) providing a rectangular body blank having a first side edge and a second side edge; b) forming a tubular container body from the rectangular body blank, the container body having a first end with a first end opening and a second end with a second end opening and a container body wall extending in a height direction of the packaging container between the first end opening and the second end opening, the container body wall having an inner surface and an outer surface; c) sealing together the first side edge and the second side edge of the body blank; d) closing the first end opening by pressing a paperboard disc into the first end opening, the paperboard disc having a peripheral flange being flexed towards the first end of the container body in the height direction of the paperboard packaging container, and sealing the peripheral flange of the paperboard disc to the inner surface of the container wall; e) pressing the first end of the tubular container body into a curl forming portion of a curling tool, the curl forming portion comprising a tool inner surface having three or more spaced apart protuberances, thereby curling the first end of the container body wall inwardly forming a first curled edge comprising a bent edge portion and an inner portion, and providing the inner portion of the first curled edge with three or more spaced apart indentations along a circumference of the tubular container body, the indentations being formed by the spaced apart protuberances of the tool inner surface; f) filling the packaging container with bulk solids; and g) closing the second end opening; wherein steps g) and subsequently step f) could alternatively be performed after step c).

2. The method of forming a paperboard packaging container according claim 1, wherein the curl forming portion is a U-shaped track having the same footprint as a container body first end such that a container body first end fit into the curl forming portion and wherein the tool inner surface is an inner surface of the curl forming portion.

3. The method of forming a paperboard packaging container according to claim 1, wherein the method comprises a step h) of pressing the second end of the tubular container body into the curl forming portion of the curling tool, thereby curling the second end of the container body wall inwardly forming a second curled edge comprising a bent edge portion and an inner portion, and providing the inner portion of the first curled edge with three or more spaced apart indentations along a circumference of the tubular container body, the indentations being formed by the spaced apart protuberances of the tool inner surface.

4. A paperboard packaging container for bulk solids, the container comprising a tubular container body being made by a laminate sheet material comprising a carton substrate layer and a container bottom, the container body extending in a height direction of the container between a first end and a second end of the container, the tubular container body comprising a container body wall, the container body wall having an inner surface facing towards an inner compartment in the packaging container and an outer surface facing away from the inner compartment, a first end opening being closed with a paperboard disc having a peripheral flange being flexed towards the first end of the container in the height direction (H) and attached to the inner surface of the container body wall, the first end of the container body being curled inwardly providing a first curled edge comprising an edge portion and an inner portion characterized in that the inner portion of the first curled edge is provided with three or more indentations being spaced apart along a circumference of the tubular container body.

5. The paperboard packaging container according to claim 4, wherein a depth, as measured in a direction perpendicular to the height direction of the packaging container, of each of the three and more indentations is from 0.2 mm or more, such as up to 6 mm.

6. The paperboard packaging container according to claim 4, wherein the tubular container body has three or more wall portions being connected by corner portions and wherein each of the wall portions comprises three or more spaced apart indentations arranged in the inner portion of the first curled edge.

7. The paperboard packaging container according to claim 6, wherein the corner portions are free from indentations.

8. The paperboard packaging container according to claim 4, wherein the tubular container body has a round or oval cross-section.

9. The paperboard packaging container according to claim 4, wherein the inner portion of the first curled edge has a height of from 2 mm to 30 mm as measured from the edge portion to an end edge of the inner portion.

10. The paperboard packaging container according to claim 4, wherein the first end opening is a bottom end opening, the paperboard disc is a bottom disc and the first curled edge is a curled bottom edge.

11. The paperboard packaging container according to claim 4, wherein the first end opening is an upper end opening, the paperboard disc is a top disc and the first curled edge is a curled upper edge.

12. The paperboard packaging container according to claim 4, wherein the second end of the container body wall is curled inwardly providing a second curled edge comprising an edge portion and an inner portion, the inner portion (38b) of the second curled edge is provided with three or more indentations being spaced apart along a circumference of the tubular container body.

13. A curling tool for forming a curled edge on a paperboard packaging container, the curling tool being a curl plate having a curl forming portion in the form of a track having the shape of a closed loop configured for receiving a tubular container body end, the curl forming portion having an inner surface outer surface and a bottom surface, the curl plate having a first main side intended to face the paperboard packaging container when forming the curled edge, the curl forming portion being provided in the first main side and where the curl forming portion has a depth (dt), as measured from the first main side to the bottom surface of the curl forming portion, characterized in that the inner surface is provided with three or more protuberances being spaced apart along a circumference of the curl forming portion.

14. The curling tool according claim 13, wherein the curl forming portion is a U-shaped track having essentially the same footprint as a container body end such that a container body end fit into the curl forming portion and wherein the tool inner surface is an inner surface of the curl forming portion.

15. The curling tool according to claim 13, wherein the three or more protuberances protrudes 0.5 mm or more from the inner surface of the curl forming portion.

16. The curling tool according to claim 13, wherein the depth of the curl forming portion is from 5 mm up to 40 mm.

17. The curling tool according to claim 13, wherein the three or more protuberances has a diameter (ø) and wherein the three or more protuberances are arranged with a spacing between adjacent protuberances corresponding at least to the diameter (ø) of the protuberances, optionally within the range of from 2 mm to 20 mm.

18. The curling tool according to claim 13, wherein the three or more protuberances has a diameter (ø) within the range of from 2 mm to 10 mm.

19. The curling tool according to claim 13, wherein the three or more protuberances are formed by studs provided in the curling tool and along the circumference of the curl forming portion.

20. The curling tool according to claim 13, wherein the three or more protuberances are aligned at level with each other along the circumference of the curl forming portion.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0069] The present invention will be further explained hereinafter by means of non-limiting examples and with reference to the appended drawings wherein:

[0070] FIG. 1 illustrates a tubular container body and a curling tool according to the present invention prior to forming of a curled edge;

[0071] FIG. 2 illustrates pressing of a first end of a tubular container body into a curl forming portion of a curling tool;

[0072] FIGS. 3-5 illustrate curling an end of a container body wall inwardly to form a curled edge;

[0073] FIG. 6 illustrates a packaging container with a curled edge according to the present disclosure; and

[0074] FIG. 7 illustrates an optional step of forming a second curled edge.

[0075] FIG. 8 illustrates a packaging container according to the present disclosure.

DETAILED DESCRIPTION

[0076] It is to be understood that the drawings are schematic and that individual components, such as layers of materials are not necessarily drawn to scale. The steps in the method of forming a packaging container and the packaging container shown in the figures are provided as examples only and should not be considered limiting to the invention. Accordingly, the scope of the invention is determined solely by the scope of the appended claims.

[0077] FIG. 1 illustrates a step in a method of forming a paperboard packaging container from a tubular container body 2. The tubular container body 2 has a first end 3 with a first end opening 4 and a second end 5 with a second end opening 6 and a container body wall 7 extending in a height direction H between the first end opening 4 and the second end opening 6. The container body wall 7 has an inner surface 8 and an outer surface 9, a first end edge 10 and a second end edge 11. In a first step (not shown) of the method according to the present disclosure the tubular container body 2 is formed by providing a body blank having a first side edge and a second side edge and forming the tubular container body by sealing together the first and second side edges of the body blank. The first end opening 4 is closed by pressing a paperboard disc 12 into the first end opening 4 (this method step not being shown). The paperboard disc 12 has a peripheral flange 13 being flexed towards the first end 3 of the container body 2 in the height direction H of the tubular container body 2. The peripheral flange 13 of the paperboard disc 12 is sealed to the inner surface 8 of the container wall 7. In this figure, the tubular container body 2 has a rectangular cross-section with a front wall portion 18, a rear wall portion 19, two side wall portions 20,21, the wall portions 18,19,20,21 being connected by curved corner portions 22,23,24,25. As set out herein, it is to be understood that the packaging container may have any suitable cross-section

[0078] FIG. 1 furthermore illustrates a curling tool 30 for forming a curled edge 14 (shown in FIG. 6) on a paperboard packaging container. The curling tool 30 is a curl plate having a curl forming portion 31 in the form of a U-shaped track having the shape of a closed loop configured for receiving the tubular container first end edge 3. In this FIG. 1 the curl forming portion has a modified rectangular shape with curved edge portions to match the cross-sectional shape of the container body 2. The curl forming portion 31 has an inner surface 32, an outer surface 34 and a curved bottom surface 35. The curl plate 30 has a first main side 36 intended to face the tubular container body 2 when forming the curled edge 14. The inner surface 32 is provided with a plurality of protuberances 33, protruding into the curl forming portion 31 from the inner surface 32 and being spaced apart along a circumference of the curl forming portion 31. The corner portions of the curl forming portion 31 are free from protuberances 33. A spacing between two adjacent protuberances 33 corresponds at least to a diameter Ø of the protuberances 33. The diameter Ø of each of the protuberances 33 may be within the range of from 2 mm to 20 mm, more preferably within the range of from 2 to 10 mm. The protuberances protrudes with a depth d of 1.5 mm or more from the inner surface 32 of the U-shaped track 31. The curl forming portion 31 has essentially the same footprint as the container body first end 3 and second end 5. In this figure the protuberances 33 are formed by studs provided in the curl plate 30 and along the circumference of the curl forming portion 31.

[0079] FIG. 1 illustrates the step after the first end opening 4 has been closed with the sealing disc 12. The tubular container body 2 and the curling tool 30 are brought together to introduce the first end 3 of the container body 2 into the curl forming portion 31.

[0080] FIG. 2 illustrates when the first end 3 of the tubular container body 2 is pressed into the U-shaped track 31 of the curling tool 30. When the tubular container body 2 is pressed into the curling tool 30, the first end 3 of the tubular container body 2 is pressed towards the bottom surface 35 of the curl forming portion 31 and follows the curvature and bends together with the curved bottom surface 35, as illustrated in FIG. 3. When pressing the first end 3 further into the curling tool 30, the first end 3 completely bends and folds itself inwardly as illustrated in FIGS. 4 and 5, thereby forming the first curled edge 14 comprising a bent edge portion 14a and an inner portion 14b. When the tubular container body 2 is pressed into the curved bottom surface 35 of the curl forming portion 31 and bends inwardly, the inner portion 14b of the curled edge 14 presses against the inner surface 32 and against the spaced apart protuberances 33 as shown in FIGS. 4 and 5. In these figures the first end 3 of the tubular container body 2 is bent over and pressed against the peripheral flange 13 of the paperboard disc 12. Optionally, the paperboard disc 12 may be arranged at a greater distance to the first end edge 10 such that the curled edge just folds over itself. The spaced apart protuberances 33 protrude out and into the curl forming portion 31 and provide additional compression of the inner portion 14b of the bent edge portion 14. The protuberances 33 press into the paperboard material and deform the carton structure layer thereby rendering the paperboard material less rigid and the curled edge 14 becomes less bulky and more distinct. The protuberances 33 break the paperboard material perpendicular to the curling direction, causing the material to be less prone to spring-back and the curl to set in the desired configuration.

[0081] FIG. 6 illustrates the tubular container body 2 after formation of the first curled edge 14. Along a circumference of the tubular container body 2, the inner portion 14b of the first curled edge 14 is provided with spaced apart indentations 15. The depth d (shown in FIG. 1) of the indentations 15 may for example be within the range of from 0.2 mm to 6 mm. The corner portions 23,24,25 at the first end 3 of the tubular body 2 are free from indentations 15. Indentations 15 in these area may otherwise render the folding of the material in the corner portions 23,24,25 bulkier and less neat. The curl forming portion 31 may have a depth d.sub.t within the range of from 5 mm up to 40 mm, such as within the range of from 10 mm to 30 mm.

[0082] In a subsequent step, not shown herein, the tubular container body is turned such that the second end opening is directed upwardly and the packaging container is filled with bulk solids. The packaging container may optionally be sealed over the second end opening with a partly or fully removable transport closure being attached to the inner surface of the container body wall.

[0083] FIG. 7 illustrates an optional step of forming a packaging container comprising a second curled edge. Prior to this step the second end opening 6 has been closed at the second end of the container body 2 with a paperboard disc 39 having a peripheral flange 40 being flexed towards the second end 5 of the paperboard packaging container 1. In this optional step, the second end 5 of the tubular container body 2 is directed upwardly and is guided towards the main side 36 of the curling plate 30 to form a second curled edge 38 provided with indentations 41, similar to the first curled edge 14, by introducing the second end 5 into the curl forming portion 31 provided with the spaced apart protuberances 33 in the same way as when forming the first curled edge 14.

[0084] In FIG. 8, a paperboard packaging container 1 for bulk solids according to the present disclosure is illustrated and as produced according to the method illustrated in FIGS. 1-7. The packaging container 1 comprises the tubular container body 2 being made by a laminate sheet material comprising a carton substrate layer, a container bottom 16 and a container lid 17. The container body 2 extending in a height direction H of the container 1 from the first end 3, corresponding to the bottom end, to the second end 5, corresponding to the upper end. in a packaging container according to the present disclosure, the first end may correspond to either the upper end or the bottom end of the packaging container.

[0085] The tubular container body 2 comprises the container body wall 7, the container body wall 7 having the inner surface 8 facing towards an inner compartment in the packaging container 1 and the outer surface 9 facing away from the inner compartment. The lid 17 of the packaging container is a plug-in lid type. The lid 17 comprises an outer circumferential lid collar 27 having a lid abutment edge 28, adapted to abut against a container body abutment edge 29, and a lid plug-in portion 37. An example of this kind of lid-type is disclosed in WO 2017/180056. In this packaging container the container opening has been closed with an upper paperboard disc 39. The upper paper board disc and the tubular container body 2 being parts of the plug-in lid. The second end 5 of the tubular container body 2 thus forms the upper end of the packaging container 1 and is the second curled edge 38 provided with indentations 41 at an inner portion 38b of the second curled edge 38, thereby providing a distinct second bent edge portion 38a

[0086] The packaging container may be provided with a lid of any suitable kind. The lid may be of the removable kind, without any permanent connection to the container body. It is further to be understood that the closure arrangement as shown in FIG. 2 is non-limiting and that the bottom end as disclosed herein may be used for packaging containers having other types of closure arrangements such as closure arrangements wherein a lid cooperates with a reinforcement rim or with a frame structure of the container body to close and open the packaging container. The lid may be provided as a part of a lid component. A lid component comprises a rim to which the lid is connected with a hinge. The rim is attached to the container body and stabilizes the container opening. The lid component may be provided with features such as locking means for keeping the lid in a closed position, tamper evidence means, stacking means, etc. as known in the art. Lid components are usually formed by injection moulding of thermoplastic material.