Method for producing conical metal objects made of thin sheet metal, and metal objects produced in this manner

Abstract

The invention relates to a method for producing a component (85) made of an aluminum sheet metal, which has a thickness ranging from 0.05 to less than 0.08 mm and a region (15) that is curved or linearly conical at least in some areas, from a pot-shaped blank which is stepped at least once and has at least two substantially cylindrical wall portions (12, 13, 84). The method is characterized in that a bottom stamp (16) is produced in a conical drawing process (65') or following such a process, said bottom stamp having a flat base (18), the plane of which is substantially perpendicular to the component axis (28), and, in a circumferential convex transition region (19) between said base (18) and the conical region (15), at least twelve depressions (20, 21), which are directed radially outward along the component axis (28) in a plan view of the component (85), are distributed regularly over the circumference, and extend towards the interior (27) of the component, each depression having a base (23) and two opposite lateral walls (24), each of which has a constricted design.

Description

[0001] TITLE

[0002] Method for producing conical metal objects from thin sheets and metal objects produced thereby

[0003] TECHNICAL FIELD

[0004] The present invention relates to methods for producing a component from a thin metal sheet, wherein the component has an at least partially curved or linearly conical region and is preferably formed from a cup-shaped blank with at least one substantially cylindrical wall section, as well as to devices for carrying out such a method and to components produced using the method. In particular, the method is suitable for the production of aerosol dome elements or capsules, particularly for food products, for example, for coffee.

[0005] STATE OF THE ART

[0006] Pot-shaped metal objects can be formed from a flat sheet of metal in a cold forming process. This typically occurs after a stamping process or combined with a stamping process in a single forming step (deep drawing), in which the finished component is given its final shape. Such processes are used, for example, for the production of pots, spray cans (or parts thereof), components in the automotive or furniture industries, food packaging, etc. Aluminum and tinplate are particularly used as materials.

[0007] Especially when using thin material thicknesses, the forming process must be carefully managed to avoid cracks, wrinkles, etc., and thus rejects or unsatisfactory quality. This applies especially to the formation of conical wall sections, because in contrast to the formation of axially cylindrical wall sections, the guidance in the tool is not guaranteed to the same extent.

[0008] US4,914,937 describes a method for forming a tapered container, in which the container is first drawn to a partial length having first and second straight sidewall portions connected by a transition portion, and then redrawn to substantially its final length and tapered state by drawing material from the transition portion. The method optionally also includes a second redrawing over the length and a bottom profiling step that uses the overdrawn portion to form the profile. EP-A-0310726 discloses a cylindrical punch / truncated cone-shaped die drawing process. The blank is subjected to one (or more) drawing operations between a die with a frustoconical inner wall and a cylindrical punch, the pressure of the clamping means being relieved to allow the metal to conform to the shape of the punch as it is deformed.The application for the production of can bodies from sheet metal with "double reduction" is also described.

[0009] EP-A-3702061 discloses a method for producing a component from a metal sheet having an at least partially curved or linearly conical region from a cup-shaped blank with a substantially cylindrical wall section. The method is characterized in that it comprises at least the following steps: a stepped drawing step, in which the cylindrical edge section of the blank is formed between a drawing die and a drawing punch displaceably guided in a fold holder into a stepped region with two cylindrical sections, and at least one subsequent conical drawing step, in which at least the stepped region is formed into the curved or linearly conical component section between two tools.

[0010] WO 2018 / 067013 describes a capsule containing a substance for preparing a drinkable beverage, the capsule comprising an aluminum capsule body with a side wall and an outwardly extending flange, and a sealing element on the outwardly extending flange for providing fluid sealing contact with an enclosing element of a preparation device. The beverage preparation device comprises an annular element having a free contact end, which may be provided with a plurality of radially extending open grooves. The sealing element is integral with the outwardly extending flange and has a projection. An annular groove between the inner projection base and the side wall has a bottom axially spaced from the outer projection base toward the bottom of the capsule body.

[0011] WO-A-2023174757 describes a method for producing a component from an aluminum sheet having a thickness in the range of 0.05 to less than 0.08 mm with an at least partially curved or linear conical region made from a cup-shaped blank with a substantially cylindrical wall section, characterized in that the method comprises at least the following steps: a step drawing, and a conical drawing which follows directly or indirectly thereafter, wherein before the step drawing a blank is punched from a flat sheet and this is formed into a cup-shaped blank, wherein the free circumferential edge is designed to be curved and widen conically at least in sections, wherein a circumferential radial flange and an axial cylindrical edge region are formed in the conical drawing, and following the conical drawing a drawing is carried out in which the conical widening is folded over in a form-fitting manner to form a folded over widening, and then the axial cylindrical edge region and the folded over widening are rolled on the bottom side with a rolling die to form a rolled edge.

[0012] WO-2016075318 describes a method for forming a beverage capsule containing one or more beverage ingredients, the method comprising the following steps: a) forming a cup-shaped body from a material web, the cup-shaped body comprising a base, a side wall and an open mouth opposite the base; b) filling one or more beverage ingredients into the cup-shaped body through the open mouth; and c) applying a lid to the cup-shaped body to close the open mouth; wherein the material web comprises a laminate material comprising at least one aluminum layer and one or more polymer layers, and wherein, after forming, the one or more polymer layers are located towards an outside of the beverage capsule and the aluminum layer is provided towards an inside of the beverage capsule.At least a first portion of the base is thinner than a second portion of the base, and the first portion of the base is thinner by displacing or removing at least a portion of the one or more polymer layers. A related beverage capsule and system are also disclosed.

[0013] PRESENTATION OF THE INVENTION

[0014] One of the problems with the existing processes is that they are only suitable for materials above a certain thickness. If the material thickness is further reduced, for example, to save material, to work more ecologically sustainably, or to meet other requirements, problems arise, including cracking, uncontrolled deformation, etc.

[0015] WO-A-2023 / 174757 proposes a method for producing a component from an aluminum sheet with a thickness in the range of 0.05 to less than 0.08 mm with an at least partially curved or linearly conical region made from a cup-shaped blank with a substantially cylindrical wall section, which is characterized in that it comprises at least the following steps: a step drawing and a conical drawing following directly or indirectly thereafter, wherein before the step drawing a blank is punched from a flat sheet and this is formed into a cup-shaped blank, wherein the free circumferential edge is designed to be curved and widen conically at least in sections, wherein a circumferential radial flange and an axial cylindrical edge region are formed in the conical drawing, and following the conical drawing a drawing is carried out in which the conical widening is folded over in a form-fitting manner to form a folded over widening, and then the axial cylindrical edge region and the folded over widening are rolled on the bottom side with a rolling die to form a rolled edge.

[0016] Using this process, pot-shaped containers can be made from this very thin material.

[0017] However, it has become apparent that the stability achieved, particularly in the base area, is insufficient for certain applications. The containers tend to buckle uncontrollably at the base under load, or, when pierced, bend instead of being pierced.

[0018] The starting point of the present invention is, in particular, such a method according to WO-A-2023 / 174757, or rather, components produced therewith, and their further or additional processing. This method as disclosed in this document is accordingly expressly included in the disclosure content of this document as a possible starting point for the method and component.

[0019] Specifically, the present invention relates to a method for producing a component from an aluminum sheet having a thickness in the range from 0.05 to less than 0.08 mm with an at least partially curved or linearly conical region, preferably starting from an at least singly stepped pot-shaped blank with at least two substantially cylindrical wall sections.

[0020] The method is characterized in that in a conical draw or subsequent to such a base embossing is produced which has a flat base whose plane is arranged substantially perpendicular to the component axis, and in a circumferential (viewed from the outside of the component) convex transition region from this base to the conical region has at least 12 depressions which, in a plan view of the component from the outside along the component axis, are directed radially outwards and are regularly distributed over the circumference towards the interior of the component.

[0021] The depressions each have a bottom and two opposite side walls, and these opposite side walls are preferably each constricted.

[0022] Preferably, this constriction or the side walls are also convex and rounded when viewed from the outside. This results in the base of the elongated recess having a narrow width in the middle, which increases towards both ends of the recess. The base of the recess transitions to the aforementioned base of the component in a bend, preferably without any further side walls; the same applies to the transition to the conical area of ​​the component.

[0023] Preferably there are 18-26 recesses, preferably 20-24 recesses, with an even number of recesses being particularly preferred.

[0024] According to a preferred embodiment, alternating first depressions are provided with a length that substantially corresponds to the length of the circumferential convex transition region between the base and the conical region or at least 80% thereof, and in each case between them second depressions with a shorter length, preferably a length that is at least 20% shorter, than that of the first depressions.

[0025] The first and second recesses are typically arranged on the side of the conical region substantially circumferentially at the same height, and only the first recesses extend substantially to the bottom.

[0026] At the same time, before or after the formation of the base embossing, a rolled edge can be formed on a circumferential, outwardly directed flange which is arranged on the side of the component facing away from the base at its opening.

[0027] It is also possible to start from a double-stepped pot-shaped blank with three essentially cylindrical wall sections.

[0028] The starting point is usually a blank made of aluminum or an aluminum alloy with a tensile strength in the range of 80 - 120 MPa, in particular aluminum of the following types EN AW-8011A, 8079, 8176, 8021, 8090, sintered 6061, sintered 2014, in each case in uncoated form or in one-sided or double-sided, possibly colored, painted form.

[0029] The at least partially curved or linearly conical region normally forms an average angle with the component axis in the range of 5-40°, preferably in the range of 7-15°, particularly preferably in the range of 8-12°. The at least partially curved or linearly conical region can be linearly conical at least in some regions, preferably having exclusively linearly conical regions, apart from any steps that may be present.

[0030] The depressions may have a length in the range of 2-10 mm, preferably in the range of 3-6 mm, wherein the first depressions preferably have a length in the range of 3-8 mm and the second depressions preferably have a length in the range of 2-6 mm.

[0031] The depressions may have a maximum depth between the bottom and the contour of the convex circumferential area in the range of 0.5-4 mm, preferably in the range of 1-3 mm.

[0032] The present invention further relates to a component produced by such a method.

[0033] Further embodiments are specified in the dependent claims.

[0034] BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Preferred embodiments of the invention are described below with reference to the drawings, which are for illustrative purposes only and are not to be construed as limiting. In the drawings:

[0036] Fig. 1 the sequence of steps according to WO-A-2023 / 174757 with the further intermediate pull and the formation of the folded widening in the groove pull;

[0037] Fig. 2 shows a possible sequence of steps for producing a container or component with a base embossing, wherein in a) a perspective view is given, in b) a side view and in c) a top view;

[0038] Fig. 3 shows a pot-shaped container with a bottom embossing in different views, wherein in a) a side view, in b) a section along AA in c), in c) a top view, in d) a perspective view obliquely from above, in e) a perspective view obliquely from below, in f) a section along BB in c) and in g) a section along BB in c) in a side view.

[0039] DESCRIPTION OF PREFERRED EMBODIMENTS

[0040] Figure 1 shows a sequence of steps according to WO-A-2023 / 174757 for the processing of thinner aluminum sheets.

[0041] The cup-shaped blank 1 with the folded edge 47 and base 8 is manufactured as described in WO-A-2023 / 174757, optionally with an edge with a larger width RA and a folding angle of up to 90° (angle between the axis of symmetry in the opening direction of the component and the radially outermost section of the edge 47).

[0042] This component 1 is formed in a step train 64 into component 2 with a base 25. Component 2 now has a stepped area 11 with an upper first cylinder section 12 with a large radius, a transition section 14, and, following this, a second cylinder section 13 with a smaller radius.

[0043] This is followed by a further intermediate pass 71, in which a further cylindrical section 84 with a radius is formed from the base 25, and the component 2' is formed after a further intermediate pass, so that in the end a base 82 with a smaller radius than the base 25 results (this radius of the base 82 does not necessarily have to be smaller). This is followed by the conical pass 65, in which the conical region 15 is formed and the component is shaped according to conical pass 3. The sections 12, 13 and 84 contribute to the formation of the conical region 15, and in the uppermost region a cylindrical section remains with a lower height than in component 2'.

[0044] This conical section 65 is now followed by a groove section 66, in which not only (optionally) a groove is formed, but also the folded edge 47 is formed into a folded widening 74 with a folding angle a of up to 90°.

[0045] This is followed by an edge roll 67.

[0046] The sequence can be followed by further embossing steps or similar.

[0047] A component manufactured by such a method can be provided with an embossing in the base area, according to the present invention, as will be explained with reference to Fig. 2

[0048] Figure 2 shows a) a possible sequence of steps. A circular blank 46 is first produced in a punch 62. This is then formed into the previously described cup-shaped component 1 in a cut-and-draw step 63, with the edge 47 being determined by the shape of the drawing die and the insertion depth. The aforementioned base 8 is provided opposite the side of the opening.

[0049] In the previously described intermediate section 64, a stepped region is now formed, comprising the first cylindrical section 12, the transition section 14, and the second cylindrical section 13. Next comes the further intermediate section 71, although it should be noted that this can also be omitted in this case if the material properties allow it. In this further intermediate section, the component 2' is formed with the third cylindrical section 84 and the base 82 with a radius.

[0050] During the cone drawing, a base embossing is now performed, i.e., the next step is a cone drawing with base embossing 65'. In this step, an embossed base 65 is formed, as will be explained in more detail in the following description. It is also possible to perform a cone drawing 65 as shown in Figure 1 without base embossing, and to perform the base embossing in a separate step or as part of the groove drawing 66 described in Figure 1, or even as part of the edge rolling step 67. It is also possible to successively form the base embossing in several steps.

[0051] In the example of Figure 2a, the conical section with base embossing 65' is followed by the formation of the circumferential flange 17, in this case flat, without groove, in the context of the edge rolling 67 and the rolled edge 55 is formed.

[0052] Figures 2b) and c) show the same sequence of steps in a side view and top view, respectively. Figure 3 shows a component, in this case a coffee capsule, with a base embossing, as can be produced using the method according to Figure 2. The reference numerals indicate the same elements in the respective figures.

[0053] The finished component 85 has the aforementioned conical region 15, followed at the top by a flat flange 17 arranged perpendicular to the component axis 28. The aforementioned rolled edge 55 is formed on the outer edge of this flange 17. The conical region 15 can be a single unstructured surface with a straight cutting line, or there can be one or more slight circumferential grooves, as shown here. Below, the conical region 15 is followed by the aforementioned embossed base 16. In this base, radially extending depressions in the form of notches are provided, distributed over the circumference and, in a top view, directed towards the interior 27. Long notches 20 and short notches 21 alternate around the circumference. The long notches 20 extend essentially from the conical region 15 to a flat base arranged perpendicular to the component axis 28.The short notches 21, on the other hand, only extend from the conical region to slightly more than half of the convex, curved transition region 19 between the conical region 15 and the base 18. The notches 20 / 21 each have a flat base 23, which is essentially a plane or slightly curved in the same sense as the convex, curved transition region 19. The notches 20 / 21 are each laterally delimited by side walls 24. These side walls each extend from the base 23 to the surface of the convex, curved transition region 19. They are doubly curved, on the one hand along the direction of the respective notch but also in a direction perpendicular to the base 23, so that the surface of the respective base 23 is narrow in the middle of the notch and widens towards the respective outer edge.In other words, the side walls 24, which are formed symmetrically on both sides, are constricted side walls.

[0054] At the respective outer edge of the respective notch, the base 23 merges into the surface of the base 18 or shortly before it, or on the other side into the surface of the conical region 15 or into an edge region of the convexly curved transition region 19. preferred masses there is no actual side wall at this transition.

[0055] It turns out that this structuring of the base, even using very thin aluminum material, provides a very stable base structure that can be pierced, especially in a coffee machine, without simply giving way and bending, as can happen with very thin material without such notches. In particular, the specific arrangement of long and short notches distributed around the perimeter proves particularly suitable for providing this stability in the base area.

[0056] LIST OF REFERENCE SYMBOLS

[0057] 1 blank

[0058] 2 Component after intermediate pull / step pull

[0059] 2' component after further intermediate pull

[0060] 3 Component after cone pull

[0061] 8 floor (section) of 1

[0062] 11 graded range of 2

[0063] 12 first cylinder section of 11

[0064] 13 second cylinder section of 11

[0065] 14 Transition section between 12 and 13

[0066] 15 conical area of ​​3

[0067] 16 embossed base

[0068] 17 circumferential flat flange

[0069] 18 flat area of ​​16

[0070] 19 convex curved transition area between 15 and 18

[0071] 20 notch (long)

[0072] 21 notch (short)

[0073] 23 floor of 20 / 21

[0074] 24 constricted side walls of 20 / 21

[0075] 25 floor of 2

[0076] 26 opening of 85

[0077] 27 Interior

[0078] 28 Component axis

[0079] 46 die cuts

[0080] 47 folded edge of 1

[0081] 55 rolled edge

[0082] 62 punches, possible separately, unless the next step is designed as a cut-pull

[0083] 63 Cut-Pull

[0084] 64 step train / intermediate train

[0085] 65 Finished train / cone train

[0086] 65' finished train / conical train with bottom stamping 66 grooved train

[0087] 67 edge rolls

[0088] 71 further intermediate train

[0089] 74 relocated widening 82 soil

[0090] 84 third cylinder section of 11

[0091] 85 finished component a folding angle

[0092] RA flange width

Claims

PATENT CLAIMS 1. A method for producing a component (85) from an aluminum sheet having a thickness in the range from 0.05 to less than 0.08 mm with an at least partially curved or linearly conical region (15), made from an at least singly stepped pot-shaped blank with at least two substantially cylindrical wall sections (12, 13, 84), characterized in that in a conical section (65') or adjacent to such a cone, a bottom embossing (16) is produced, which has a flat bottom (18), the plane of which is arranged substantially perpendicular to the component axis (28), and in a circumferential convex transition region (19) from this bottom (18) to the conical region (15), at least 12, in a plan view of the component (85) along the component axis (28), radially outwardly directed depressions (20, 21) regularly distributed over the circumference towards the interior (27) of the component, wherein the depressions each have a bottom (23) and two respectively opposite side walls (24), and these opposite side walls (24) are each constricted. are.

2. Method according to claim 1, characterized in that there are 18-26 depressions (20, 21), preferably 20-24 depressions (20, 21), wherein particularly preferably an even number of depressions (20, 21) is provided.

3. Method according to one of the preceding claims, characterized in that alternating first depressions (20) with a length which substantially corresponds to the length of the circumferential convex transition region (19) between the base (18) and the conical region (15) or at least 80% thereof, and in that in each case second depressions (21) with a shorter length, preferably a length at least 20% shorter, than that of the first depressions (20) are arranged between them.

4. Method according to claim 3, characterized in that the first and second recesses (20, 21) on the side of the conical region (15) are arranged substantially circumferentially at the same height, and only the first recesses (20) extend substantially to the bottom (18).

5. Method according to one of the preceding claims, characterized in that at the same time, before or after the formation of the base embossing (16) on a circumferential, outwardly directed flange (17) which is arranged on the side of the component (16) facing away from the base (18) at the opening (16), a rolled edge (55) is formed.

6. Method according to one of the preceding claims, characterized in that the starting point is a double-stepped pot-shaped blank with three substantially cylindrical wall sections (12, 13, 84).

7. Method according to one of the preceding claims, characterized in that the starting material is a blank made of aluminum or an aluminum alloy, with a tensile strength in the range of 80 - 120 MPa, in particular aluminum of the following types EN AW-8011A, 8079, 8176, 8021, 8090, sintered 6061, sintered 2014, in each case in uncoated form or in one-sided or two-sided, optionally colored, painted form.

8. Method according to one of the preceding claims, characterized in that the at least partially curved or linearly conical region (15) has a mean angle with the component axis (28) of the component (3) in the range of 5-40°, preferably in the range of 7-15°, particularly preferably in the range of 8-12° and / or that the at least partially curved or linearly conical region (15) is at least partially linearly conical, preferably, apart from any steps that may be present, has exclusively linearly conical regions.

9. Method according to one of the preceding claims, characterized in that the depressions have a length in the range of 2-10 mm, preferably in the range of 3-6 mm, wherein the first depressions (20) preferably have a length in the range of 3-8 mm and the second depressions (21) preferably have a length in the range of 2-6 mm.

10. Method according to one of the preceding claims, characterized in that the depressions (20.21) have a maximum depth between the bottom (23) and the contour of the convex circumferential region (19) in the range of 0.5-4 mm, preferably in the range of 0.5 and 1 mm.

11. Component (85) manufactured by a method according to one of the preceding claims.

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