Paper lids and methods for their manufacture

Abstract

The invention relates to a paper lid (D) and a method for its manufacture, comprising a lid disc (1) and a lid ring (2) having a longitudinal axis (L2) 5 and a circumferential wall (3) extending in the direction of the longitudinal axis (L2) with an inner surface (3A) and an outer surface (3B) as well as a first end (3C) and a second end (3D), wherein on its outer circumference it has a U-shaped region (1.2) with a first wall section (1.3) and a second wall section (1.4) which are connected to each other via a third wall section 10 (1.5), and wherein the lid ring (2) engages with its first end (3C) in the U-shaped region (1.2) of the lid disc (1) such that the first wall section (1.3) abuts the inner surface (3A) and the second wall section (1.4) abuts the outer surface (3B), and wherein the first wall section (1.3) and the second wall section (1.4) of the U-shaped area (1.2) the cover disc with the first 15 end (3c) of the cover ring (2) are materially bonded. According to the method, a pre-drawn conical cover disc (2) is first produced, which has an edge region (4) and a flat region (1.1) offset therefrom by a conical shoulder (5), such that a cover ring (2) is positioned on the conical shoulder (5) and that subsequently at least one region of the conical shoulder (5) is formed against an inner surface 20 3A and the edge region (4) against an outer surface (3B) of the wall (3) of the cover ring (1) and sealed with it.

Description

The invention relates to a paper lid and a method for its manufacture according to the preamble of claims 1 and 4. For example, DE 830891 B already discloses two-part paper lids with a first paper element representing the circumferential lateral, mostly vertical edge, and with a second paper element representing an inner horizontal lid end, as well as with a third paper element representing an outer horizontal lid end. Documents US 2014 / 0 144 923 A1 and EP 2 674 369 A1 also reveal two-part paper covers, which are designed as a material-fit combination of a cover plate and a cover ring. In both of the aforementioned documents, the cover ring forms a material-fit, U-shaped grip. This structure is relatively elaborate and the manufacturing process is complicated. The object of the invention is to develop a paper lid that can be produced simply and cost-effectively from two parts using a suitable method and a device, and which has sufficient stability to close a container several times and is stackable in one version. This problem is solved using the features of claims 1, 4, 5 and 6. Advantageous embodiments result from the dependent claims. The lid according to the invention consists of paper and / or paper composite and comprises a lid disc and a lid ring having a longitudinal axis and a circumferential wall extending in the direction of the longitudinal axis, with an inner surface and an outer surface, as well as a first end and a second end, wherein the lid disc and lid ring are bonded together in a material-bonded manner, and wherein the lid disc has a planar area extending transversely to the longitudinal axis, which engages in the lid ring, and on its outer circumference a U-shaped area adjoining the planar area, comprising a first wall section and a second wall section, which are connected to each other via a third wall section, and wherein the lid ring engages with its first end in the U-shaped area of ​​the lid disc in such a way thatthat the first wall section rests against the inner surface and the second wall section against the outer surface, and that the first wall section and the second wall section of the U-shaped area of ​​the cover disc are materially bonded to the first end of the cover ring. To enable stacking, the wall of the lid ring can be drawn inwards / towards the longitudinal axis in its area that engages the U-shaped area of ​​the lid disc, so that a shoulder is preferably formed below the lid disc. To ensure stackability, the outer diameter of the lid disc is smaller than the inner diameter of the wall of the lid ring in the area of ​​the open second end, which is facing away from the lid ring. When stacking, the inner diameter of one lid overlaps the outer diameter of the lid below it in the area of ​​the lid disc, and the open second end rests on the shoulder of the lid below. Alternatively, the lid is made of paper, consisting of a lid disc and a lid ring having a longitudinal axis and a circumferential wall extending in the direction of the longitudinal axis, with an inner surface and an outer surface, as well as a first end and a second end, wherein the lid disc and lid ring are bonded together such that the lid disc has a planar area extending transversely to the longitudinal axis, and has on its outer circumference a U-shaped area adjoining the planar area, with a first wall section and a second wall section, which are connected to each other via a third wall section, and wherein the lid ring engages with its first end in the U-shaped area of ​​the lid disc such thatthat the first wall section rests against the inner surface and the second wall section against the outer surface, and that the first wall section and the second wall section of the U-shaped area of ​​the lid disc are materially bonded to the first end of the lid ring, and wherein the first and second wall sections of the lid disc and the intermediate end of the wall of the lid ring are aligned parallel to the longitudinal axis of the lid ring, and the first and second wall sections extend in a straight line. In the inventive method for producing the lid according to the invention, a pre-existing conical lid disc is first produced, which has an edge region and a flat region offset thereto by a conical shoulder, and wherein a lid ring with a first end of its wall is positioned on the outer circumference of the conical shoulder or within the conical shoulder, and subsequently at least one region of the conical shoulder is formed against an inner surface and the edge region against an outer surface of the wall of the lid ring and is joined to it in a material-bonded manner. To enable stacking of the lid, the wall of the lid ring can be drawn inwards towards the longitudinal axis of the lid ring when it is connected to the lid disc. Alternatively, the wall of the lid ring can be drawn inwards towards the longitudinal axis at one end before being connected to the lid disc. As a further alternative, the wall of the lid ring can also be drawn inwards towards the longitudinal axis at one end after it has been connected to the lid disc. According to an alternative method for manufacturing a lid, a pre-formed conical lid disc is first produced, which has an edge region and a planar region offset thereto by a conical shoulder, a lid ring with a first end of a wall on the outer circumference of the conical shoulder or within the conical shoulder is positioned, and subsequently at least one region of the conical shoulder is formed against an inner surface and the edge region against an outer surface of the wall (3) of the lid ring and sealed with it, wherein a first and a second wall section of the lid disc and the end of the wall of the lid ring located between them are aligned parallel to a longitudinal axis of the lid ring and the first and the second wall section extend in a straight line. The invention is explained in more detail below with reference to an exemplary embodiment and associated drawings. The figures show: Fig. 1 starting part for the preformed lid disc, Fig. 2 preformed / predrawn lid disc, Fig. 3 lid ring, Fig. 4 lid disc positioned on the lid ring, Fig. 5 stackable lid produced from lid disc and lid ring in longitudinal section, Fig. 6 detail X according to Fig. 5, Fig. 7 several lids stacked on top of each other according to Fig. 5, Fig. 8 longitudinal section of a non-stackable lid, Fig. 9 lid disc and lid ring inserted into a tool, Fig. 10 tool after joining / sealing the lid disc and lid ring, Fig. 11 variant of producing the indentation on the lid ring before joining with the lid disc, Fig. 12 schematic representation of producing the connection between the lid disc and lid ring with a previously produced indentation on the lid ring, Fig. 13 three-dimensional representation of a lid according to the invention. Fig. 1 shows the starting part 1' of a lid disc, which consists of a flat piece of paper or cardboard cut to the shape of the lid. The starting part can be round, oval, kidney-shaped, or otherwise shaped in plan view, depending on the desired shape of the lid. The starting part 1' has a coating on its underside 1a suitable for creating a material-bonded connection, preferably in the form of a sealing medium, in particular a sealing layer or sealing film, which is not shown here. The sealing medium can, for example, be laminated, extruded, or applied as a sealing lacquer. It consists, for example, of PE (polyethylene). A barrier layer not shown here can be arranged between the sealing medium and the underside 1 a of the lid disc (e.g. in the form of a ceramic coating or made of aluminum foil, PET (polyethylene terephthalate) or EVOH (ethylene vinyl alcohol copolymer)). The conically projecting cover plate 1 in the sectional view is shown in Fig. 2. This plate has an outer edge region 4 and a substantially planar region 1.1 offset from it by a conical shoulder 5. This planar region can be flat, as shown here, or curved towards or opposite the edge. Furthermore, the substantially planar region can contain one or more grooves (not shown). The lid ring 2 shown in Fig. 3 was preferably manufactured from paper using a winding process, and in particular spirally wound. The lid ring 2 has a circumferentially closed wall 3, the shape of which is adapted to the lid shape to be produced and thus to the lid disc 1 (e.g., round, oval, kidney-shaped, etc.). The lid ring 2 has a longitudinal axis L2 and an inner diameter d2. The wall 3 has an inner surface 3A and an outer surface 3B, as well as a first end 3C and an opposite second end 3D. In addition to or as an alternative to the lid disc 1 with sealing medium, the inner surface 3A and / or the outer surface 3B of the lid ring 2 can also be provided with sealing medium, at least in the connection area with the lid disc 1, as described for the lid disc 1, and may also have a barrier layer. To create the connection between the cover disc 1 and the cover ring 2, the cover ring 1 is placed onto the first end 3C of the cover sleeve 2 (see Fig. 4). Advantageously, the conical shoulder 5 serves to center the cover sleeve 2 or the cover disc 1 relative to the cover ring 2. Now, using appropriate tools (not shown), the upper, unlabeled area of ​​the wall 3 of the lid sleeve 2 is formed radially inwards towards the longitudinal axis L2 (indicated by the inward-pointing arrows), and the edge area 4 of the lid disc 1 is bent downwards (indicated by the downward-pointing arrows). In doing so, the edge area 4 of the lid sleeve 1 is pressed against the outer surface 3B, and the conical shoulder 5 of the lid sleeve 1 is pressed against the inner surface 3A of the lid sleeve 2. Under pressure and heat, a material-bonded connection, in particular by sealing, is created between the lid disc 1 and the lid ring 2. The temperature required for sealing is usually between 100°C and 350°C, depending on the sealing medium, and, for example, between 120°C and 200°C when PE is used as the sealing medium. After forming and creating the material-bonded connection, the lid D is finished and the lid disc 1 has a U-shaped area 1.2 at its edge (see Fig. 5 and Fig. 6) into which the wall 3 of the lid ring 2 engages, the wall 3 being material-bonded to the U-shaped area 1.2 at its inner surface 3A and its outer surface 3B. The lid D has a cup-shaped depression 6.1 with a depth t1 and an inner diameter d1 in the area of ​​the lid disc 1. The lid D has an outer diameter D1 in the area of ​​the lid disc 1. Wall 3 has an inner diameter d2 from shoulder 3.1 to the second end 3D. The detail shown in Fig. 6 reveals that the U-shaped area 1.1 adjoining the substantially planar area 1.1 has an inner first wall section 1.3 (leg) which is connected to the inner surface 3A of the wall of the cover ring 2, and that a second wall section 1.4 (leg) is bonded to the outer surface 3B of the wall 3 of the cover ring 2 (preferably by sealing). The first and second wall sections 1.3, 1.4 of the cover disc 1 and the end 3C of the wall 3 of the cover ring 2 located between them are oriented substantially parallel to the longitudinal axis L2 of the cover ring 2, with the first and second wall sections 1.3, 1.4 extending substantially in a straight line. The first wall section 1.3 and the second wall section 1.4 of the U-shaped area 1.2 of the cover disc 1 are connected to each other via a third wall section 1.5. The wall 3 is drawn radially inwards / inwards towards the longitudinal axis L2 at the end 3C which engages in the U-shaped area 1.2 of the cover disc 1, thereby forming a shoulder 3.1 below the second wall section 1.4 of the U-shaped area. The inner diameter d2 of the wall 3, from the shoulder 3.1 to the second end 3D, is slightly larger than the outer diameter D1 in the area of ​​the cover disc 1, so that, for stacking, the inner diameter d2 of one cover D can be placed over the outer diameter D1 of the cover disc 1 of another cover D. The second end 3D of one cover D then rests on the shoulder 3.1 of the other cover D. The wall 3 of the cover sleeve 2 has an outer diameter D2 from the shoulder 3.1 to the second end 3D. Figure 7 shows an example of four stacked lids D in longitudinal section. The upper lid D engages with its inner diameter d2 of the lower part of the lid sleeve 2 over the outer diameter D1 of the second wall section of the U-shaped area (not shown here) and thus the outer diameter D1 of the lid disc 1. Fig. 8 shows a lid D according to the invention which is not stackable. This lid also has a lid disc 1 with a substantially planar area 1.1 and an adjoining U-shaped area 1.1 with an inner first wall section 1.3 (leg) which is connected to the inner surface 3A of the wall 3 of the lid ring 2, and a second wall section 1.4 (leg) which is bonded to the outer surface 3B of the wall 3 of the lid ring 2 (preferably by sealing). The first and second wall sections 1.3, 1.4 of the lid disc 1 and the end 3C of the wall 3 of the lid ring 2 located between them are also oriented substantially parallel to the longitudinal axis L2 of the lid ring 2, with the first and second wall sections 1.3, 1.4 extending substantially in a straight line. The first wall section 1.3 and the second wall section 1.4 of the U-shaped area 1.2 of the cover disc 1 are connected by a third wall section 1.5 connected to each other. The wall 3 of the lid ring 2 extends in a straight line and parallel to the longitudinal axis L2 over the entire length of the lid ring. In both embodiments – stackable and non-stackable – the lid D according to the invention thus consists of two parts in the form of a lid disc 1 and a lid ring 2, which are joined together by a material bond. The straight connection areas between the lid disc 1 and the lid ring 2 create a lid D that extends in a substantially straight line. The following is an example of how to manufacture a stackable lid using appropriate tools. First, a pre-existing conical cover disc 2 is produced which has an edge area 4 and a flat area 1.1 offset from it by a conical step 5. The cover ring 2 is positioned, as shown in Fig. 9, with its inner diameter d2 on the unlabeled outer diameter of a lower tool 6, such that the first end 3C of the wall 3 of the cover ring 2 projects by a length L beyond a radially inwardly projecting shoulder 6.1 of the lower tool 6. The pre-drawn conical cover ring 1 is then placed with the underside of its edge region 4 onto the first end 3C of the wall 3 and positioned here on the outer circumference of the conical shoulder 5. An upper tool 7 now moves downwards and holds the cover ring 1 by fixing it at the radius between the conical shoulder 5 and the flat area 1.1 with a circumferential edge 7.1 against the radially inner end of the shoulder 6.1 of the lower tool 6. The upper tool 7 has an outer diameter D7, which corresponds to the later inner diameter d1 of the cover disc 1 of the finished cover D. Now a ring punch 8 moves from the direction of the upper tool 7 towards the lower tool 6. The ring punch 8 has an inner diameter 8d2 in the direction of the lower tool 6, which corresponds to or is slightly larger than the outer diameter D2 of the cover ring 2. Adjoining the diameter 8d2 is a radially inwardly projecting chamfer 8.1, which runs essentially parallel to the shoulder 6.1 of the lower tool 6. Adjoining the chamfer is an inner diameter 8d1, which corresponds approximately to the outer diameter D1 of the finished cover D in the area of ​​the cover disc 1. The tool is heated, at least in the area of ​​the joining zone between the cover disc 1 and the cover ring 2, although this is not shown. The final position of the ring punch 8 is shown in Fig. 10. During its stroke towards the lower tool, the edge region 4 of the cover disc 1 was formed downwards and pressed against the outer diameter of the cover ring 2. Due to the inclined surface 8.1 and the subsequent smaller inner diameter 8d1 of the ring punch 8, the upper region 3c of the cover ring 2, the adjacent edge region 4, and the conical region 5 of the cover disc 2 were pressed radially inwards against the outer diameter D7 of the upper tool 7. The pressure and sealing temperature (preferably between 120°C and 300°C) create a metallurgical bond between the cover disc 1 and the cover ring 2 in the area where the first end 3C of the wall 3 of the cover ring is now located between the wall sections 1.3 and 1.4 of the cover disc 1. The unlabeled gap formed between the outer diameter D7 and the inner diameter 8d1 is slightly less than the sum of the thicknesses of the wall sections 1.3 and 1.4 of the cover disc 2 and the wall 3 of the cover ring 2 located between them, thus generating pressure through compression. After the sealing process is completed, the ring die 8 moves upwards, the lower tool 6 and the upper tool 7 are opened and the lid is ejected by means of an ejector not shown. It is also possible to create the indentation of the first end 3C of the wall 3 of the cover ring 2 before or after the connection with the cover disc. This is done, for example, as indicated in Fig. 11, by a rolling process of the wall 3 between an outer roller 9 (or an outer rail) and an inner roller 10. These have a corresponding contour corresponding to the wall indentation to be produced. The advantage of this method is that a circumferential groove can also be created simultaneously in the wall area of ​​the cover sleeve, which is present in a large number of covers. According to Fig. 12, the edge region 4 and the conical region 5 of the cover disc 1 are also formed against the radially inwardly shaped region of the wall of the cover ring 2 and sealed with it. A stackable lid D according to the invention is shown in Fig. 13. It is closed at the top by the lid disc 1, which is materially bonded to the lid ring 2. The outer diameter D1 in the area of ​​the lid disc 1 is smaller than the outer diameter D2 in the area of ​​the lid ring 2, thereby forming a step 3.1. The inner diameter of the lid D, which is not specified here, engages with the outer diameter D1 for stacking. Reference symbol list 1' Starting part 1a Underside 1 Cover disc 1.1 Flat area 1.2 U-shaped area 1.3 First wall section 1.4 Second wall section 1.5 Third wall section 1.6 Recess 2 Cover ring 3 Wall 3A Inner surface 3B Outer surface 3C First end 3D Second end 3.1 Shoulder 4 Edge area 5 Conical step Cover ring 6 Lower tool 6.1 Shoulder Lower tool 7 Upper tool 7.1 Circumferential edge 8 Ring punch 8.1 Bevel 8d1 Inner diameter Ring punch 8d2 Inner diameter Ring punch 9 Outer roller 10 Inner roller d1 Inner diameter Cover disc d2 Inner diameter Cover ring / Wall t1 Depth D Cover D1 Outer diameter Cover disc D7 Outer diameter Upper tool L Length L2 Longitudinal axis

Claims

A paper lid (D) comprising a lid disc (1) and a lid ring (2) having a longitudinal axis (L2) and a circumferential wall (3) extending in the direction of the longitudinal axis (L2) with an inner surface (3A) and an outer surface (3B) as well as a first end (3C) and a second end (3D), wherein the lid disc (1) and the lid ring (2) are bonded together, characterized in that the lid disc (1) has a planar region (1.1) extending transversely to the longitudinal axis (L2), and has on its outer circumference a U-shaped region (1.2) adjoining the planar region with a first wall section (1.3) and a second wall section (1.4) which are connected to each other via a third wall section (1.5), and wherein the lid ring (2) engages with its first end (3C) in the U-shaped region (1.2) of the lid disc (1) such that the first wall section (1.3) on the inner surface (3A) and the second wall section (1.4) on the outer surface (3B) and that the first wall section (1.3) and the second wall section (1.4) of the U-shaped area (1.2) of the lid disc are materially connected to the first end (3c) of the lid ring (2) and that the wall (3) in its area which engages in the U-shaped area (1.2) of the lid disc (1) is drawn inwards / in the direction of the longitudinal axis (L2) and thereby forms a shoulder (3.1) below the lid disc. Lid according to claim 1, characterized in that the outer diameter (D1) of the lid disc (1) is smaller than the inner diameter (d3) of the wall (3) of the lid ring (2) in the region of the second end 3D. Lid according to claim 1 or 2, characterized in that it is stackable, wherein the inner diameter (d2) of a lid (D) extends over the outer diameter (D1) of a lid (D) below it and the second end (3C) rests on the shoulder (3.1) of the lid (D) below it. A paper lid (D) comprising a lid disc (1) and a lid ring (2) having a longitudinal axis (L2) and a circumferential wall (3) extending in the direction of the longitudinal axis (L2) with an inner surface (3A) and an outer surface (3B) as well as a first end (3C) and a second end (3D), wherein the lid disc (1) and the lid ring (2) are bonded together, characterized in that the lid disc (1) has a planar region (1.1) extending transversely to the longitudinal axis (L2), and has on its outer circumference a U-shaped region (1.2) adjoining the planar region with a first wall section (1.3) and a second wall section (1.4) which are connected to each other via a third wall section (1.5), and wherein the lid ring (2) engages with its first end (3C) in the U-shaped region (1.2) of the lid disc (1) such that the first wall section (1.3) on the inner surface (3A) and the second wall section (1.4) on the outer surface (3B) and that the first wall section (1.3) and the second wall section (1.4) of the U-shaped area (1.2) of the lid disc (1) are materially connected to the first end (3c) of the lid ring (2) and- wherein the first and the second wall section (1.3, 1.4) of the lid disc (1) and the end (3C) of the wall (3) of the lid ring (2) located between them are aligned parallel to the longitudinal axis (L2) of the lid ring (2) and the first and the second wall section (1.3, 1.4) extend in a straight line. A method for manufacturing a lid (D) according to claim 1, characterized in that a pre-formed conical lid disc (1) is first produced, which has an edge region (4) and a planar region (1.1) offset therefrom by a conical shoulder (5), that a lid ring (2) with a first end (3C) of a wall (3) is positioned on the outer circumference of the conical shoulder (5) or within the conical shoulder (5), and that subsequently at least one region of the conical shoulder (5) is formed against an inner surface (3A) and the edge region (4) against an outer surface (3B) of the wall (3) of the lid ring (1) and sealed with it, and that the wall (3) of the lid ring (1) is drawn inwards towards the longitudinal axis (L2) of the lid ring (1) when connected with the lid disc (1), or that the wall of the lid ring (1) is drawn inwards at a first end (3C) towards the longitudinal axis (L2) before or after being connected with the lid disc (1). is being withdrawn. A method for producing a lid (D) according to claim 1, characterized in that a pre-formed conical lid disc (1) is first produced, which has an edge region (4) and a planar region (1.1) offset therefrom by a conical shoulder (5), that a lid ring (2) with a first end (3C) of a wall (3) is positioned on the outer circumference of the conical shoulder (5) or within the conical shoulder (5), and that subsequently at least one region of the conical shoulder (5) is formed against an inner surface (3A) and the edge region (4) against an outer surface (3B) of the wall (3) of the lid ring (1) and sealed with it, wherein a first and a second wall section (1.3, 1.4) of the lid disc (1) and the intermediate end (3C) of the wall (3) of the lid ring (2) are aligned parallel to a longitudinal axis (L2) of the lid ring (2), and the first and the second wall section (1.3, 1.4) extend in a straight line.

Images