Packaging container, and method for manufacturing such a packaging container

Abstract

A cardboard packaging container for bulk solids, and a method of forming a cardboard packaging container for bulk solids. The container has a container body with one end closed by a lid formed by sequentially inserting and attaching a first cardboard insert and a second cardboard insert.

Description

Technical Field

[0001] [Cross - Reference to Related Applications] This application claims the benefit of Swedish Patent Application No. 2250951 - 7, filed on August 5, 2022.

[0002] [Incorporation by Reference] The disclosure of Swedish Patent Application No. 2250951 - 7, filed on August 5, 2022, is incorporated herein by reference in its entirety for all purposes as if fully set forth herein.

[0003] The present disclosure relates to a method for manufacturing a cardboard packaging container for bulk solids and a cardboard container for bulk solids.

Background Art

[0004] In the field of disposable containers for products such as infant formula, tobacco, detergents, etc., it is continuously necessary to minimize the use of resources for disposable containers and make the containers recyclable in order to reduce the carbon dioxide emissions of such products. The disposable containers referred to herein are composite containers having a tubular body made from a laminated sheet material including a carton layer, i.e., a layer mainly made of cellulose fibers. The upper and lower edge portions of the container can include a plastic rim connected to the edge of the packaging container. This provides a packaging container with a comfortable and neat appearance, and the upper or bottom part of the container can also be more wear - resistant. The bottom of the container may alternatively be made from a folded end portion of the tubular body or may be a bottom insert / disk attached to the tubular body at the bottom end. However, the appearance of such a packaging container is somewhat lacking in attractiveness and wear resistance at the bottom end of the packaging container.

[0005] Accordingly, an object of the present disclosure is to provide an improved packaging container that provides better stability and easier opening of the lid of the container. Another object is to provide a method for manufacturing such a container.

SUMMARY OF THE INVENTION

[0006] In one aspect, the present disclosure generally relates to a method of forming a paperboard packaging container for a bulk solid. The method includes obtaining a body blank having a first side edge and a second side edge, the body blank being made from a laminated sheet material including a carton substrate layer. The method includes forming a container body from the body blank, the container body defining an internal compartment and having a container body wall with an inner surface facing the internal compartment, an outer surface facing away from the internal compartment, and a weakened portion extending along at least a portion of the circumference of the container body, the container body having a first end with a first end opening and a second end opposite the first end with a second end opening. The method includes closing the first end opening by pushing a first paperboard insert into the first end opening to a first predetermined position relative to the container body to form an outer recess, the first paperboard insert including a first central portion covering the first end opening and a first peripheral flange portion at the first predetermined position of the first paperboard insert. The method includes attaching the first peripheral flange portion of the first paperboard insert to the container body wall at a first attachment portion of the container body, the weakened portion in the container body wall being between the first attachment portion and the second end of the container body. The method includes pushing a second paperboard insert having a second central portion covering the first end opening and a second peripheral flange portion through the first end opening into the outer recess to a second predetermined position relative to the container body. The method includes attaching the second peripheral flange portion of the second paperboard insert to the container body wall.

[0007] According to another aspect, the present disclosure relates to a cardboard packaging container for a bulk solid. The container includes a container body that defines an internal compartment. The container body includes a container body wall made of a laminated sheet material including a carton base material layer. The container body includes a first end having a first end opening and a second end opposite the first end having a second end opening. The container body wall has an inner surface facing the internal compartment and an outer surface facing away from the internal compartment. A first cardboard insert closes the first end opening, and the first cardboard insert includes a first central portion covering the first end opening and a first peripheral flange portion. The first cardboard insert is disposed within the container body and forms an outer recess. The first peripheral flange portion is attached to the inner surface of the container body wall at a first attachment portion of the container body. The container body has a weakened portion extending along at least a portion of the perimeter of the container body. The weakened portion is between the first attachment portion and the second end of the container body. The packaging container further includes a second cardboard insert positioned within the outer recess and covering the first end opening. The second cardboard insert includes a second central portion and a second peripheral flange portion attached to the container body wall.

[0008] According to one aspect, the above object is achieved by a method of forming a cardboard packaging container according to the subject matter of the claims, the following description and the drawings. In one embodiment, the method is a method of forming a cardboard packaging container from a body blank. The method includes step a) of obtaining a body blank having a first side edge and a second side edge, the body blank being made of a laminated sheet material including a carton base material layer.

[0009] The method also includes step b) of forming a tubular container body from the body blank.

[0010] The method also includes step c) of sealing both the first side edge portion and the second side edge portion. The tubular container body defines an internal compartment, and the container body includes a container body wall having an inner surface facing the internal compartment and an outer surface facing away from the internal compartment. The container body includes a first end having a first end opening and a second end opposite the first end having a second end opening.

[0011] The method also includes step d) of closing the first end opening by pushing a first cardboard insert into the container body within the first end opening to a first predetermined position. The first cardboard insert includes a first central portion covering the first end opening and a first peripheral flange portion directed away from the first central portion towards the first end opening of the container body such that an outer recess of the packaging container is formed.

[0012] The method also includes step e) of attaching the first peripheral flange portion of the first cardboard insert to the container body wall.

[0013] The method also includes step f) of pushing a second cardboard insert through the first end opening into the outer recess within the container body to a second predetermined position. The second cardboard insert includes a second central portion covering the first end opening and a second peripheral flange portion directed away from the second central portion towards the first end opening of the container body.

[0014] The method also includes step g) of attaching the second peripheral flange portion of the second cardboard insert to the container body wall.

[0015] By attaching the first and second cardboard inserts to the container body wall, a double-wall lid structure is formed by the first and second cardboard inserts. The lid structure is stronger than the single-wall lid structure formed when using only one cardboard insert, i.e., it has a larger cross-sectional area and enables the stability of the lid for packaging containers made of weaker materials. The increased stability of the lid also enables easier handling of the lid when separating it from the rest of the packaging container while reducing the risk of lid breakage / deformation.

[0016] The method can further include step h) of deforming the second central portion of the second cardboard insert before attaching the second peripheral flange portion to the container body wall so that the concave portion of the second cardboard insert is formed adjacent to the second peripheral flange portion, and the concave portion is shaped such that the distance between the second central portion of the second cardboard insert and the first central portion of the first cardboard insert decreases at the concave portion.

[0017] By deforming the second central portion before attaching the second peripheral flange portion to the container body wall, the material of the cardboard insert can move freely during deformation, and as a result, the material of the cardboard blank used to form the cardboard insert can move from the peripheral portion of the second cardboard blank used to form the second cardboard insert, thereby reducing the elongation of the cardboard material during the deformation of the second central portion of the second cardboard insert.

[0018] Step f) may be performed by pushing the second cardboard insert into the outer recess using the footprint surface of the press tool, and the footprint surface has a shape and dimensions adapted to the shape and dimensions of the first end opening of the container body and has a protrusion for forming the concave portion of the second cardboard insert.

[0019] Step f) can include positioning the guide plate adjacent to the first end opening of the container body such that the through cavity of the guide plate is aligned with the first end opening of the container body, the through cavity having a shape and dimensions corresponding to the shape and dimensions of the first end opening of the container body, the second paper insert being guided into the outer recess through the through cavity of the guide plate when the second paper insert is pushed into the outer recess, and the second peripheral flange portion being bent between the guide plate and the press tool.

[0020] The use of such a guide plate protects the first end of the container body such that deformation of the paper blank occurs as a result of forces acting on the paper blank mainly by the guide plate and the press tool, rather than between the container body wall and the press tool.

[0021] The through cavity of the guide plate can have a recessed portion that extends the through cavity in a direction transverse to the insertion direction in which the second paper insert is inserted into the outer recess, the recessed portion of the through cavity being positioned adjacent to where the protrusion of the footprint surface passes through the through cavity.

[0022] The recessed portion can reduce the area / marginal length of the through cavity of the guide plate along which the blank slides during deformation between the press tool and the guide plate, i.e., increase the local stress applied to the portion of the paper blank such that the paper blank is bent at the intended location when the second peripheral flange portion is bent away from the second central portion of the second paper insert.

[0023] According to a second aspect, the above object is also achieved by a cardboard packaging container according to the claims, the following description and the drawings. The packaging container is suitable for bulk solids and the container comprises a tubular container body defining an internal compartment. The container body comprises a container body wall made of a laminated sheet material including a carton base material layer, and has a first end having a first end opening and a second end opposite thereto having a second end opening. The container body wall has an inner surface facing the internal compartment within the packaging container and an outer surface facing away from the internal compartment. The first end opening is closed by a first cardboard insert having a first central portion covering the first end opening. The first cardboard insert further comprises a first peripheral flange portion directed away from the first central portion towards the first end opening of the packaging container such that an outer recess of the packaging container is formed. The first peripheral flange portion is attached to the inner surface of the container body wall at a first attachment portion of the container body. The container body also has a weakening portion extending along at least a part of the perimeter of the container body, the weakening portion being between the first attachment portion and the second end of the container body. The packaging container further comprises a second cardboard insert positioned within the outer recess and covering the first end opening. The second cardboard insert comprises a second central portion and a second peripheral flange portion directed away from the second central portion towards the first end opening of the packaging container. The second peripheral flange portion can be attached to the inner surface of the container body wall or to the first peripheral flange portion of the first cardboard insert.

[0024] The first cardboard insert and the second cardboard insert are both attached to the container body wall. When opening the packaging container, the user typically grasps the first end of the container body by grasping the second peripheral flange portion of the second cardboard insert and pulls so that the container body wall separates at the weakened portion. Since the weakened portion is between the first attachment portion and the second end of the container body, both the first cardboard insert and the second cardboard insert together form a lid that includes the torn or upper portion of the container body wall. The combination of the two cardboard inserts improves the rigidity of the lid and facilitates handling of the lid while separating the lid from the remaining portion of the container body and after separation.

[0025] The second central portion of the second cardboard insert may be provided with a concave portion adjacent to the container body wall.

[0026] The concave portion adjacent to the container body wall makes it easier for the user to grasp the lid when peeling the lid from the remaining portion of the container body by increasing the surface area available for the user to grip. The concave portion also visually indicates to the user the location to grip, i.e., removing the lid is made easier because pulling at an arbitrary position would be more difficult.

[0027] The second cardboard insert may be formed from a cardboard blank, which includes a central portion having a shape and dimensions corresponding to the shape and dimensions of the first end opening of the container body, and a peripheral portion surrounding the central portion.

[0028] As shown in Figure 3, the peripheral portion of the cardboard blank may be enlarged adjacent to the portion of the cardboard blank where the concave portion is formed.

[0029] By expanding the paperboard blank adjacent to the location where the recessed portion is formed, additional material is available for forming the recessed portion without reducing the amount of material available for forming the second peripheral flange portion. This enables the second peripheral flange portion to be attached to the container using a weld or adhesive bond that extends planar around the circumference of the first end opening of the packaging container.

[0030] The second central portion of the second paper insert can be provided with a gripping opening that can be covered by a removable cover.

[0031] The gripping opening provides an alternative to the recess described above. The gripping opening allows the user to grip the lid through the gripping opening, i.e., reach a larger surface area of the lid for gripping. The gripping opening may be covered by a separate lid member or film, or by providing at least partially extending perforations, stitches, etc. around the circumference of the gripping opening so that the user can access the gripping opening by pushing a cover into the space between the first paper insert and the second paper insert, or by lifting or tearing the cover, and may be covered by a portion made from the same paperboard blank as the second paper insert.

[0032] As shown in FIG. 5, the removable cover may be a part of the second central portion integrally formed with the second paper insert and may be at least partially surrounded by the stitches of the second central portion.

[0033] The cover may be hingedly connected to the second cardboard insert by a hinge. By joining the cover by a hinge, the cover can be easily lifted or lowered to open and close the gripping opening of the second cardboard insert. This makes it possible to use the intermediate space between the first cardboard insert and the second cardboard insert for storage purposes and to easily and repeatedly access the object stored in the intermediate space. For example, a spoon can be stored in the intermediate space and replaced after use.

[0034] The present disclosure will be further described below by way of non-limiting examples with reference to the accompanying drawings.

Brief Description of the Drawings

[0035]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

DETAILED DESCRIPTION OF THE INVENTION

[0036] Like reference numerals indicate like features throughout the drawings. The reference numerals may be omitted in some drawings for better visibility, in which case other drawings are referred to.

[0037] It should be understood that the drawings are schematic and that individual components such as layers of materials are not necessarily drawn to scale. Each step in the method of forming the packaging container 1 and the packaging container 1 shown in the drawings are provided by way of example only and should not be considered as limiting the present disclosure.

[0038] First, with reference to the accompanying drawings, an exemplary embodiment of the packaging container 1 will be described. Then, a method for manufacturing the packaging container 1 will be described.

[0039] As shown in FIGS. 2 and 8, the packaging container 1 includes a tubular container body 2 that defines an internal compartment 28. The container body 2 includes a container body wall 7 made of a laminated sheet material including a carton base material layer, and has a first end 3 having a first end opening 4 and an opposite second end 5 having a second end opening 6. The container body wall 7 has an inner surface 8 facing the internal compartment 28 of the packaging container 1 and an outer surface 9 facing away from the internal compartment 28. The first end opening 4 is closed by a first cardboard insert 12a having a first central portion 121a covering the first end opening 4. The first cardboard insert 12a further includes a first peripheral flange portion 13a directed toward the first end opening 4 of the packaging container 1 away from the first central portion 121a such that an outer recess 122 of the packaging container 1 is formed. The first peripheral flange portion 13a is attached to the inner surface 8 of the container body wall 7 at a first attachment portion 129 of the container body 2.

[0040] Also, as shown, for example, in the enlarged portion C of FIG. 14, the container body 2 has a weakened portion 130 extending along at least a portion of the perimeter of the container body 2, and the weakened portion 130 is between the first attachment portion 129 and the second end 5 of the container body 2. In the present embodiment, the weakened portion 130 includes a perforation extending around the entire perimeter of the packaging container 1, but in other embodiments, instead, any other suitable type of weakened portion, such as a fold line or a peel tape, may alternatively be used.

[0041] As shown in FIG. 14, the first peripheral flange portion 13a preferably extends beyond the weakened portion 130, so that when the lid of the packaging container 1 is closed (when the packaging container 1 is opened by peeling off the lid at the weakened portion 130 of the container body 2), the lid including the first cardboard insert 12a can be guided into the container body 2 by the first peripheral flange portion 13a.

[0042] The above-described structure of the container body 2 is common to all embodiments of the packaging container 1 of the present disclosure and corresponds to the container body 2 shown in FIG. 6.

[0043] As shown in FIGS. 2 and 8, the packaging container 1 further includes a second paper insert 12b that is positioned within the outer recess 122 and covers the first end opening 4. The second paper insert 12b includes a second central portion 121b and a second peripheral flange portion 13b that is directed away from the second central portion 121b toward the first end opening 4 of the packaging container 1. The second peripheral flange portion 13b is attached to the inner surface 8 of the container body wall 7. Alternatively, the second peripheral flange portion 13b can be attached to the first peripheral flange portion 13a of the first paper insert 12a without departing from the scope of the present disclosure.

[0044] In the illustrated embodiment, both the first paper insert 12a and the second paper insert 12b are attached to the container body wall 7. When opening the packaging container 1, the user typically grasps the first end 3 of the container body 2 by grasping the second peripheral flange portion 13b of the second paper insert 12b and pulls so that the container body wall 7 separates at the weakened portion 130. Since the weakened portion 130 is between the first attachment portion 129 and the second end 5 of the container body 2, both the first paper insert 12a and the second paper insert 12b together form a lid that includes a cutout portion (e.g., the upper portion) of the container body wall 7 that separates at the weakened portion 130. The combination of the two paper inserts 12a and 12b improves the rigidity of the lid and makes it easier to handle the lid during and after separating the lid from the remaining portion of the container body 2.

[0045] As shown in FIGS. 2 and 8, the second central portion 121b of the second paper insert 12b includes a recess 123 that is adjacent to the container body wall 7. In other embodiments, two or more such recesses 123 may be provided.

[0046] The concave portion 123 adjacent to the container body wall 7 makes it easier for the user to grasp the lid when peeling it off from the rest of the container body 2 by increasing the available surface area for the user to grip. The concave portion 123 also visually indicates to the user the location for gripping, i.e., since it is more difficult to pull the lid away from the rest of the container when pulling at an arbitrary location, it further facilitates removing the lid.

[0047] The second paper insert 12b is formed from the paper blank 131a shown in FIG. 3. The paper blank 131a includes a central portion 132a having a shape and dimensions corresponding to the shape and dimensions of the first end opening 4 of the container body 2. The central portion 132a is shown by a dashed line in FIG. 3. The second paper insert 12b also includes a peripheral portion 133a surrounding the central portion 132a. The peripheral portion 133a of the paper blank 131a is enlarged adjacent to the portion of the paper blank 131a where the concave portion 123 is formed.

[0048] By enlarging the paper blank 131a adjacent to the location where the concave portion 123 is formed, additional material is available for forming the concave portion 123 without reducing the amount of material available for forming the second peripheral flange portion 13b. This also enables the second peripheral flange portion 13b to be attached to the container body wall 7 using a welded or adhesive bond that extends planar around the circumference of the first end opening 4 of the packaging container 1.

[0049] As described above, the second central portion 121b of the second paper insert 12b may alternatively include a gripping opening 136 instead of the concave portion 123 in other embodiments. The gripping opening 136 may be covered by a removable cover 137 as shown in FIGS. 4 and 5.

[0050] The gripping opening 136 provides an alternative to the aforementioned recess 123. The gripping opening 136 enables the user to grasp the lid of the packaging container 1 through the gripping opening 136, i.e., to reach a larger surface area of the lid for grasping. The gripping opening 136 may be covered by a separate lid member or film, or by pushing a cover 137 into the space between the first paper insert 12a and the second paper insert 12b, or by providing at least partially extending slits, perforations, etc. around the opening so that the user can gain access to the opening by lifting or peeling off the cover 137. It may also be covered by a part of the material made from the same paper blank as the second paper insert 12b.

[0051] The movable / removable cover 137 may be a part of the second central portion 121b integrally formed with the second paper insert 12b and may be at least partially surrounded by the perforations of the second central portion 121b.

[0052] The cover 137 can be hingedly connected to the second paper insert 12b by a hinge 139. By joining the cover 137 with the hinge 139, the cover 137 can be easily lifted or lowered to open and close the gripping opening 136 of the second paper insert 12b. Thereby, the intermediate space between the first paper insert 12a and the second paper insert 12b can be used for storage purposes, and repeated access to the object stored in the intermediate space can be easily achieved. For example, a spoon can be stored in the intermediate space so that it can be easily accessed and replaced after use. The hinge 139 is typically an unperforated portion of the second paper insert 12b, but in other embodiments, it may be a piece of elastic material such as a sheet material attached to the cover 137 and the second paper insert 12b by an adhesive or welding.

[0053] The packaging container 1 may be manufactured using any suitable method, and one exemplary method of manufacturing the packaging container 1 will be described below with reference to the accompanying drawings.

[0054] The method includes step a) of obtaining a body blank 134 having a first side edge portion 135a and a second side edge portion 135b, the body blank 134 being made from a laminated sheet material including a carton base material layer. Such a body blank 134 is schematically shown in FIG. 1. The method also includes step b) of forming a tubular container body 2 from the body blank 134, including step c) of sealing both the first side edge portion 135a and the second side edge portion 135b together. The tubular container body 2 defines an inner compartment 28. The container body 2 also includes a container body wall 7 having an inner surface 8 facing the inner compartment 28 and an outer surface 9 facing away from the inner compartment 28. The container body 2 includes a first end 3 having a first end opening 4 and an opposite second end 5 having a second end opening 6.

[0055] As shown in FIG. 9, the method further includes step d) of closing the first end opening 4 by pushing a first cardboard insert 12a into the first end opening 4 of the container body 2 up to a first predetermined position P1. The first cardboard insert 12a includes a first central portion 121a covering the first end opening 4 and a first peripheral flange portion 13a directed toward the first end opening 4 of the container 1 away from the first central portion 121a such that an outer recess 122 of the packaging container 1 is formed. As shown in FIG. 9, a plurality of dots represent the contents of the inner compartment 28 of the packaging container 1. Alternatively, the contents may be filled into the container body 2 from the bottom / second end 5 of the container body 2 after one or both of the cardboard inserts 12a and 12b are inserted into the container body 2.

[0056] The method further includes step e) of attaching the first peripheral flange portion 13a of the first cardboard insert 12a to the container body wall 7. For example, a suitable type of welding may be used for the attachment.

[0057] The method also includes step f) of pushing a second cardboard insert 12b through a first end opening 4 into an outer recess 122 up to a second predetermined position P2 with respect to the container body 2. The second cardboard insert 12b includes a second central portion 121b covering the first end opening 4, and also includes a second peripheral flange portion 13b directed towards the first end opening 4 of the container body 2 away from the second central portion 121b. The second predetermined position P2 is above the first predetermined position P1 within the container body 2.

[0058] The method also includes step g) of attaching the second peripheral flange portion 13b of the second cardboard insert 12b to the container body wall 7. For example, an appropriate type of welding may be used for the attachment.

[0059] By further pushing the second cardboard insert 12b into the outer recess 122 and attaching it to the container body wall 7, a double - wall lid structure is formed by the first cardboard insert 12a and the second cardboard insert 12b. The lid structure is stronger than the single - wall prior - art lid structure formed when using only one cardboard insert 12a.

[0060] The method can further include step h) of deforming the second central portion 121b of the second cardboard insert 12b before attaching the second peripheral flange portion 13b to the container body wall 7, such that a recessed portion 123 of the second cardboard insert 12b is formed adjacent to the second peripheral flange portion 13b. The recessed portion 123 is shaped such that the distance D between the second central portion 121b of the second cardboard insert 12b and the first central portion 121a of the first cardboard insert 12a decreases at the recessed portion 123.

[0061] Before attaching the second peripheral flange portion 13b to the container body wall 7, by deforming the second central portion 121b, the material of the paper blank used to form the second paper insert 12b can move from the peripheral portion of the second paper blank used for the formation of the second paper insert 12b, so that the material of the second paper insert 12b can move freely during deformation, thereby reducing the elongation of the paper material during the deformation of the second central portion 121b of the second paper insert 12b.

[0062] As shown in FIGS. 11 and 13, step f) may be performed by pushing the second paper insert 12b into the outer recess 122 using the footprint surface 53 of the press tool 27. The footprint surface 53 has a shape and dimensions adapted to the shape and dimensions of the first end opening 4 of the container body 2 and has a protrusion 128 for forming the recess portion 123 of the second paper insert 12b. The protrusion 128 of the press tool 27 may be integrally formed with the footprint surface 53 of the press tool 27 without departing from the present disclosure, or may be provided as a separate member attached to the press tool 27 to modify the footprint surface 53.

[0063] As shown in FIGS. 11, 12 and 13, step f) may include positioning the guide plate 125 adjacent to the first end opening 4 of the container body 2 such that the through cavity 126 of the guide plate 125 is aligned with the first end opening 4. The through cavity 126 has a shape and dimensions corresponding to the shape and dimensions of the first end opening 4 of the container body 2. The second paper insert 12b is guided into the outer recess 122 through the through cavity 126 of the guide plate 125 when pressing the second paper insert 12b into the outer recess 122, and the second peripheral flange portion 13b is bent between the guide plate 125 and the press tool 27.

[0064] The guide plate 125 typically also comprises alignment recesses 138 shaped to align the cardboard blanks 131a and 131b with the through cavity 126 of the guide plate 125.

[0065] The use of such a guide plate 125 protects the first end 3 of the container body 2, such that the deformation of the cardboard blank occurs mainly as a result of the forces acting on the cardboard blank by the guide plate 125 and the press tool 27, rather than between the container body wall 7 and the press tool 27.

[0066] It should be understood that two different press tools 27 may be required, one for the first cardboard insert 12a and one for the second cardboard insert 12b. The press tool 27 used for the first cardboard insert 12a does not have a protrusion 128 for forming a recess, while the press tool 27 used for the second cardboard insert 12b may have a protrusion 128 as shown in FIG. 11. If the second cardboard insert 12b does not have a recessed portion 123, the same press tool 27 can be used for both the first cardboard insert 12a and the second cardboard insert 12b.

[0067] Similarly, as shown in FIGS. 10 and 12, two different guide plates 125 may be required, one for the first cardboard insert 12a and one for the second cardboard insert 12b.

[0068] The through cavity 126 of the guide plate 125 used for the second cardboard insert 12b has a recessed portion 127 that extends the through cavity 126 in a direction transverse to the insertion direction ID in which the second cardboard insert 12b is inserted into the outer recess 122. The recessed portion 127 of the through cavity 126 is positioned adjacent to the location where the protrusion 128 of the footprint surface 53 passes through the through cavity 126.

[0069] The concave portion 127 increases the local stress on the portion of the paperboard blank such that when the paperboard blank slides between the pressing tool 27 and the guide plate 125 during deformation, the area / edge length of the through cavity 126 of the guide plate 125 is reduced, i.e., when the second peripheral flange portion 13b is bent away from the second central portion 121b of the second paperboard insert 12b, the paperboard blank is bent at the intended position.

[0070] The concave portion 127 of the through cavity 126 has a dovetail shape.

[0071] The dovetail shape provides a relatively sharp corner at the opening of the concave portion 127, thereby allowing greater control over where the material of the blank is bent when the blank is pressed through the guide plate 125.

[0072] The protrusion 128 of the footprint surface 53 can include an outer surface portion 128a that faces the container body wall 7 when inserted into the outer recess 122. The outer surface portion 128a has a shape corresponding to the shape of an adjacent portion of the container body wall 7 when inserted into the outer recess 122, and the width W1 of the opening of the concave portion 127 corresponds to the width W2 of the outer surface portion 128a of the protrusion 128 of the footprint surface 53. In one example, the shape of the outer surface portion 128a is curved to correspond to the curved shape of an adjacent portion of the container body wall 7. The outer surface portion 128a can have other shapes (e.g., straight lines) without departing from the present disclosure.

[0073] The correspondence between the width W2 of the outer surface portion 128a and the width W1 of the opening of the concave portion 127 concentrates stress on the paperboard material of the blank, thereby improving control over where the material of the blank is bent when the blank is pressed through the guide plate 125.

[0074] In other embodiments, for example, when the quality of the paperboard used for the paperboard blank is selected, the concave portion 127 may not be required. Therefore, alternatively, the concave portion 127 may be omitted. In some embodiments, the concave portion 127 may have any other suitable shape that promotes a predetermined deformation of the peripheral edges of the paperboard blanks 131a and 131b.

[0075] The pressing tool 27 may be configured as shown in FIGS. 9, 11, 13, and 14 and corresponds to a "positioning unit" further described in U.S. Patent No. 11,292,625, which is incorporated herein by reference in its entirety for all purposes. However, alternatively, any other suitable pressing tool, such as a properly shaped piston, can be used.

[0076] Also, a holding device 23 is used to position and support the container body 2 while the paperboard inserts 12a and 12b are inserted into the container body 2. The holding device 23 can correspond to the holding device further described in U.S. Patent No. 11,292,625, which is incorporated herein by reference.

[0077] Accordingly, the holding device 23 includes at least one through-hole positioning cavity adapted to receive a portion of the container body 2.

[0078] To achieve the above-described attachment of the peripheral flange portions 13a and 13b of the paperboard inserts to the container body 2, the holding device 23 preferably includes a welding unit disposed around the positioning cavity. The welding unit (not shown) is adapted to weld the paperboard inserts 12a and 12b to the container body 2, for example, by a welding unit having a coil extending around the positioning cavity. Since the pressing tool 27 is radially expandable as described herein with respect to the diameter of the positioning cavity, each of the paperboard inserts 12a and 12b can be pressed against the welding unit. Any suitable welding technique, such as ultrasonic welding or high-frequency welding, can be used, and high-frequency welding is preferred.

[0079] As an alternative or complement to welding, an adhesive may be applied to the paperboard insert before attaching the paperboard insert to the container body 2.

[0080] The press tool 27 includes a base plate 49 that includes or is composed of a rigid material such as metal or composite material, and a plunger skirt 51 that includes an elastically deformable material such as rubber or plastic. The plunger skirt 51 is disposed on the upper portion of the base plate 49 so as to at least partially cover the upper surface 54 of the base plate 49, and the upper surface 54 is on the opposite side of the lower footprint surface 53 of the base plate 49.

[0081] The footprint surface 53 is configured to face the paperboard insert during application of the paperboard insert into the container body 2. It should be understood that the footprint surface 53 can have any other suitable shape adapted to the cross-sectional shape of the packaging container 1 to be manufactured.

[0082] The plunger skirt 51 is deformable between a non-expanded state (see FIG. 11) and an expanded state (see FIG. 13) by relative movement with respect to the base plate 49.

[0083] In the non-expanded state of the plunger skirt 51, the shape of the outer contour of the plunger skirt 51 corresponds to the shape of the outer contour of the base plate 49. Thus, in the non-expanded state, the plunger skirt 51 has substantially the same footprint as the base plate 49.

[0084] Referring to FIG. 13, in the expanded state, the cross-sectional area (footprint) defined by the outer periphery of the plunger skirt 51 is larger than that in the non-expanded state of the plunger skirt 51.

[0085] The second end opening 6 of the container body 2 can be closed in the same manner as the first end opening 4.

[0086] The paperboard blanks 131a and 131b can be preformed in separate method steps using any suitable preforming device to form the paperboard blanks 131a and 131b into the first paperboard inserts 12a and 12b, enabling the first paperboard inserts 12a and 12b to be more easily fitted within the first end openings 4, i.e., the first paperboard inserts 12a and 12b obtain most of their desired shape and any creases or crease lines before being inserted into the container body 2.

Claims

Claim 1 A method of forming a paperboard packaging container for a bulk solid, comprising: obtaining a body blank having a first side edge and a second side edge, the body blank being made from a laminated sheet material including a carton base material layer; forming a container body from the body blank, the container body defining an internal compartment and having a container body wall including an inner surface facing the internal compartment, an outer surface facing away from the internal compartment, and a weakened portion extending along at least a portion of the perimeter of the container body, the container body having a first end with a first end opening and a second end opposite the first end with a second end opening; closing the first end opening by pushing a first paperboard insert into the first end opening to a first predetermined position relative to the container body to form an outer recess, the first paperboard insert including a first central portion covering the first end opening and a first peripheral flange portion at the first predetermined position of the first paperboard insert; attaching the first peripheral flange portion of the first paperboard insert to the container body wall at a first attachment portion of the container body, the weakened portion of the container body wall being between the first attachment portion and the second end of the container body; pushing a second paperboard insert including a second central portion covering the first end opening and a second peripheral flange portion into the outer recess through the first end opening to a second predetermined position relative to the container body; attaching the second peripheral flange portion of the second paperboard insert to the container body wall; A method characterized by including the above steps. Claim 2 The method according to claim 1, wherein the first peripheral flange portion extends away from the first central portion toward the first end opening of the container body, and the second peripheral flange portion extends away from the second central portion toward the first end opening of the container body. Claim 3 The method according to claim 1, further comprising deforming the second central portion of the second paper insert so that the concave portion of the second paper insert is formed adjacent to the second peripheral flange portion before the step of attaching the second peripheral flange portion to the container body wall.

4. The method according to claim 3, wherein the concave portion is formed such that the distance between the second central portion of the second paper insert and the first central portion of the first paper insert decreases in the concave portion.

5. The step of pushing the second paper insert into the outer recess includes positioning the second paper insert in the outer recess using a footprint surface of a press tool, the footprint surface having a shape and dimensions adapted to the shape and dimensions of the first end opening of the container body and having a protrusion for forming the concave portion of the second paper insert. The method according to claim 4, characterized in that.

6. The step of pushing the second paper insert into the outer recess includes positioning the guide plate adjacent to the first end opening of the container body such that a through cavity of the guide plate having a shape and dimensions corresponding to the shape and dimensions of the first end opening of the container body is aligned with the first end opening, guiding the second paper insert through the through cavity of the guide plate into the outer recess, and forming the second peripheral flange portion between the guide plate and the press tool. The method according to claim 5, characterized in that it comprises.

7. The through cavity of the guide plate has a concave portion extending the through cavity laterally with respect to the insertion direction in which the second paper insert is inserted into the outer recess, and the concave portion of the through cavity is positioned adjacent to the protrusion of the footprint surface when the press tool passes through the through cavity. The method according to claim 6, characterized in that.

8. The concave portion of the through cavity has a double-tail shape. The method according to claim 6, characterized in that.

9. The protruding portion on the footprint surface includes an outer surface portion facing the container body wall when the pressing tool is inserted into the outer concave portion, and the outer surface portion has a shape corresponding to the shape of an adjacent portion of the container body wall. The method according to claim 8, characterized in that.

10. The width of the opening of the concave portion corresponds to the width of the outer surface portion of the protruding portion on the footprint surface. The method according to claim 9, characterized in that.

11. The second predetermined position is above the first predetermined position. The method according to claim 1, characterized in that.

12. The method according to claim 1, further comprising the step of closing the second end opening at the second end.

13. A cardboard packaging container for bulk solids, The packaging container includes a container body defining an internal compartment, the container body having a container body wall made of a laminated sheet material including a carton base material layer, the container body having a first end having a first end opening and a second end opposite the first end having a second end opening, The container body wall has an inner surface facing the internal compartment and an outer surface facing away from the internal compartment, The packaging container further includes a first cardboard insert for closing the first end opening, the first cardboard insert having a first central portion covering the first end opening and a first peripheral flange portion, the first cardboard insert being disposed within the container body and forming an outer concave portion, the first peripheral flange portion being attached to the inner surface of the container body wall at a first attachment portion of the container body, The container body has a weakening portion extending along at least a portion of the perimeter of the container body, the weakening portion being between the first attachment portion and the second end of the container body, The packaging container further includes a second cardboard insert positioned within the outer concave portion and covering the first end opening, the second cardboard insert having a second central portion and a second peripheral flange portion attached to the container body wall. A cardboard packaging container, characterized in that.

14. The first peripheral flange portion extends away from the first central portion toward the first end opening of the container body, and the second peripheral flange portion extends away from the second central portion toward the first end opening of the container body. The paperboard packaging container according to claim 13, characterized in that.

15. The second central portion of the second paperboard insert includes a concave portion adjacent to the container body wall. The paperboard packaging container according to claim 13, characterized in that.

16. The concave portion is shaped such that the distance between the second central portion of the second paperboard insert and the first central portion of the first paperboard insert decreases in the concave portion. The paperboard packaging container according to claim 15, characterized in that.

17. The second paperboard insert is formed from a paperboard blank, the paperboard blank having a central portion with a shape and dimensions corresponding to the shape and dimensions of the first end opening of the container body, and a peripheral portion surrounding the central portion. The peripheral portion of the paperboard blank is enlarged adjacent to the portion of the paperboard blank where the concave portion is formed. The paperboard packaging container according to claim 15, characterized in that.

18. The second central portion of the second paperboard insert includes a gripping opening. The paperboard packaging container according to claim 13, characterized in that.

19. The paperboard packaging container according to claim 18, further comprising a cover covering the gripping opening.

20. The cover is a part of the second central portion integrally formed with the second paperboard insert and is at least partially surrounded by a perforation of the second central portion. The paperboard packaging container according to claim 19, characterized in that.

21. The cover is hingedly connected to the second paperboard insert by a hinge. The paperboard packaging container according to claim 19, characterized in that.

22. The first paperboard insert is positioned at a first position within the container body, and the second paperboard insert is positioned at a second position above the first position within the container body. The paperboard packaging container according to claim 13, characterized in that.

23. The first paperboard insert and the second paperboard insert include a lid. The paperboard packaging container according to claim 13, characterized in that.

24. The cardboard packaging container according to claim 23, wherein the lid includes an upper portion of the container body that is separable from the container body at the weakened portion. **Claim 25** The cardboard packaging container according to claim 24, wherein the lid is at least partially removable from the container body at the weakened portion.

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