US20230415219A1

US20230415219A1 - Method for producing a metal container

Info

Publication number: US20230415219A1
Application number: US18/252,022
Authority: US
Inventors: Willem Leendert Pieter Van Dam
Original assignee: Ardagh Metal Beverage Europe GmbH; Ardagh Metal Packaging Europe GmbH
Current assignee: Ardagh Metal Packaging Europe GmbH
Priority date: 2020-11-09
Filing date: 2021-11-05
Publication date: 2023-12-28
Also published as: EP4240545A1; MX2023005299A; WO2022096650A1; CA3197832A1; DE102020129484A1

Abstract

Method for producing a metallic container (1) from a sheet material (2), the container (1), which is produced at least by deep drawing and/or extrusion along an axial direction (3), having at a first end (4) a base region (5) which at least partially closes the first end (4) and, adjoining the base region (5), a wall region (8) which extends along the axial direction (3) to a second end (6) and is formed circumferentially in a circumferential direction (7).

Description

The present invention relates to a method of manufacturing a metallic container from a sheet material. The container is in particular a part of a can, in particular a part of a beverage can. In particular, the can comprises at least two parts, firstly the container, and secondly a lid region which is joined to the container, for example by a seamed joint (fold joint).
The container is produced at least by deep drawing or stretch-glide drawing along an axial direction. At a first end, the container has a base region which at least partially, in particular completely, closes the first end and, adjoining this, a wall region which extends along the axial direction to a second end and is formed circumferentially in a circumferential direction.
In particular, a lid or a lid region can be attached to the second end. The lid can in particular have a closure via which a content of the container closed by the lid can be removed.
The container can, for example, be part of a beverage container, in particular a (metallic) beverage can. The beverage container is used to store a content, e.g. a liquid, whereby the beverage container in the closed state (initial state) can be under an overpressure relative to the environment or relative to an atmospheric pressure of approximately 1 bar.
Known two-piece containers or cans closed by a lid have a base region with an adjacent cylindrical wall region, which determine the volume of the container, which are produced in one piece in a single operation by deep drawing and/or stretch-glide drawing. The wall thickness of the wall region in these containers is, for example, of the order of approximately 0.080 mm [millimeters] to approximately 0.160 mm, with the greatest thickness in the area of the subsequent connection with the lid, while the wall thickness of the base region is of the order of approximately 0.220 mm to approximately 0.350 mm. A lid may be arranged on the side of the (suitably prepared) wall region opposite to the base region. The lid is joined to the wall region of the can in the usual manner, for example by means of a so-called double folding seam. The wall thickness of the lid has, in particular, a wall thickness in the order of 0.180 mm to approx. 0.230 mm.
Containers of this type are used in significant quantities, especially for beverages of all kinds, as disposable packaging, with a large proportion of the can material being made from recycled material. Considering the large volume of the market, a significant amount of material (especially tinplate—that is steelmaterial coated with tin—or aluminum) is required. Even relatively small quantities of material that can be saved on a single container during its manufacture would, in relation to the total annual consumption of around five billion cans in the Federal Republic of Germany alone, represent a considerable and in any case non-negligible material saving.
Particularly in the case of beverage cans with carbonated contents, the beverage container can be under an internal pressure of up to 6.2 bar before it is opened for the first time. For this reason, the base region in particular must be dimensionally stable and have a sufficient wall thickness.
Any reduction in the amount of material required for a container already has a significant effect, especially in terms of material costs, due to the large lot size. For this reason, there is a constant need to increasingly reduce the wall thickness of the container. However, further reduction of the wall thickness involves the risk of material failure, especially during the additional forming operations of the base region that are sometimes required and/or due to the maximum compressive load that occurs.
It is therefore the task of the invention to at least partially solve the problems existing with respect to the prior art and, in particular, to provide a method for manufacturing a container by means of which a reproducible quality of thin-walled containers manufactured from the thinnest possible starting material can be ensured.
These tasks are solved by a method according to the features of claim 1 and by a sheet material according to the features of claim 13. Further advantageous embodiments are indicated in the dependent claims. It should be noted that the features listed individually in the dependent claims can be combined with one another in a technologically useful manner and define further embodiments of the invention. In addition, the features indicated in the claims are further specified and explained in the description, wherein further preferred embodiments of the invention are illustrated.
A method for manufacturing a metallic container from a sheet material is proposed. The container, which is produced at least by deep-drawing and/or stretch-slide-drawing along an axial direction, has at a first end a base region which at least partially closes the first end and, adjoining the base region, a wall region which extends along the axial direction to a second end and is formed circumferentially in a circumferential direction. The method comprises at least the following steps:

- a) providing the sheet material;
- b) contacting the sheet material in an annular first area with a first punch and
- c) subsequent deep drawing and/or stretch-glide drawing of the sheet material to form the base region and the wall region.

Between steps a) and b), in a step a1) the sheet material is at least partially formed in a second area, the second area at least partially comprising the first area. A material thickness/wall thickness of the sheet material present in this second area is reduced by the forming and thus at least a yield strength R_p0,2of the sheet material is increased.
In the known production of a container, a (circular) sheet section is first cut out of a flat continuous material and (immediately) then formed. This forming initially comprises, in particular, deep drawing, whereby a (second) punch, which can be moved in particular along the axial direction, forms the sheet material or the sheet section into a cup-like container. The cup-like container is then fed to a further forming station, in which the cup-like container is further formed by deep drawing and/or stretch-slide drawing. In particular, a first punch, which can be moved in particular along the axial direction, hits the base region of the cup-like container and draws the sheet material through a die (possibly a multi-stage die). In the process, the base region and the wall region of the container are at least partially formed, in particular by stretch-slide drawing. However, as a result of the impact of the first punch on the base region of the cup-like container, the sheet material is locally damaged in the first area where the first punch first contacts the sheet material and the wall thickness is locally reduced.
In further forming processes, in particular of the base region, this damage can be displaced, e.g. in a radial direction further inwards. In that way, it is precisely this damaged area that may possibly be the subject of further forming, so that further damage or even a failure of the material may occur or a critical weak point may be formed. In particular, the locally reduced wall thickness is further reduced during further forming, resulting in a wall thickness that is too thin for the intended use of the container.
Pretreatment of the first area can result in reducing or preventing a damage that occurs as a result of the contacting of the first punch and, if necessary, at least reducing or completely suppressing further damage that occurs as a result of further forming.
This is achieved in particular by at least partial forming of the sheet material in a second area in step a1), the second area at least partially or completely comprising the first area. A material thickness of the sheet material present in this second area is reduced by the forming and thus at least one yield strength R_p0,2of the sheet material is increased.
This increase in the yield strength and/or the strain hardening of the sheet material achieved by the forming process means that the impact of the first punch causes only minor deformation of the first area. It is further achieved that the sheet material present in this second area is not further deformed or is only further deformed to a lesser extent in further forming operations due to the strain hardening. In particular, when adjacent areas are formed, there is no subsequent flow of sheet material from this second area, but from other areas. This prevents a further reduction in material thickness from occurring in this second area.
In particular, a deliberate reduction of a material thickness in the second area (and an associated solidification of the sheet material) prevents or reduces a further reduction of the material thickness at a later stage.
This allows sheet materials with lower material thicknesses to be provided for the manufacture of containers without causing material failure during the manufacture of the container or during the subsequent predetermined use of the container.
In particular, the second area is annular-shaped or annular-segment-shaped. In particular, the annular-segment-shaped second area (or a plurality of annular-segment-shaped second regions arranged together within an imaginary annular-shaped second region) comprises along a circumferential direction an angular range of (together) at least 180 angular degrees, in particular of at least 270 angular degrees. In particular, the individual annular segments each extend over the angular ranges being identical, but possibly also angular ranges being different from one another, e.g. of at least 5 angular degrees in each case or at least 25 angular degrees in each case.
In particular, the second area is circular-annular-(segment-) shaped.
In particular, the first area is circular-annular-shaped and corresponds (in particular at least) to the contact surface or the impact surface of the first punch on the sheet material.
In particular, the second area is arranged coaxial with the first area.
In particular, the annular first area is bounded by a (smallest) first inner diameter and a (largest) first outer diameter. In particular, the annular or annular segment-shaped second area is bounded by a (smallest) second inner diameter and a (largest) second outer diameter. In particular, the second inner diameter is smaller than the first inner diameter.
In particular, each inner diameter is parallel to and coaxial with the outer diameter of the same area.
In particular, a second inner diameter is parallel to and coaxial with the first inner diameter.
In particular, the second outer diameter is larger than the first outer diameter.
The first diameters are determined in particular on the flat, still undeformed sheet section or sheet material, e.g. also on the basis of the first punch. The second diameters can be determined and specified as a function of the first diameters.
In particular, between steps a) and b) in a step a2), the sheet material is contacted with a second punch and subsequently deep-drawn. The second punch has a larger punch outer diameter than the first punch.
As already explained above, in the known production of a container, a (circular) sheet section is first cut out of a flat continuous material and (immediately) then formed. This forming initially comprises, in particular, deep drawing, with a second punch forming the sheet material or the sheet section into a cup-like container. This forming into the cup-like container is carried out in particular before step b) in step a2).
In particular, step a2) takes place after step a1), i.e. is performed thereafter. However, step a1) can also take place after step a2) but before step b).
30 In particular, the material thickness in the second area (as a result of the forming of the second area) is reduced by at least 3%, preferably at least 5%, particularly preferably at least 6%, and the yield strength R_p0,2is increased by at least 5%, preferably at least 10%, particularly preferably at least 15% or even at least 17%.
In conducted tryouts on an aluminum alloy, a reduction in material thickness in the second area from 245 μm [microns] to 230 μm (i.e., a reduction of 6.1%) and, at the same time, a strain hardening from a yield strength R_p0,2of 276 MPa [megapascals] to 325 MPa (i.e., an increase of 17.75%) were determined.
In particular, step c) is carried out at least partially with the first punch, whereby during or subsequent to step c), in a step c1), further forming of the base region is carried out by a third punch, which may be arranged immovably. A third area of the sheet material arranged inside the first punch, as seen in a radial direction, is formed by the third punch along the axial direction towards the second end.
In particular, the first punch is designed as a hollow punch, with the third punch entering at least partially into a hollow section of the first punch along the axial direction towards the end of step c1). In particular, the third punch has a convex contact surface relative to the base region, so that a concave shape is formed in the base region as seen from the outside.
In particular, as a result of the further forming of the base region according to step c1), the second area is displaced inward in the radial direction so that, after the further forming, the second area is arranged along the radial direction between the first punch and the third punch.
The forming of the base region according to step c1) leads in particular to a further increase in the surface area of the sheet material in the base region. This further reduces the material thickness in the base region. In particular, sheet material from adjacent regions is also displaced inwards in the radial direction as a result of the forming.
In particular, the second area is also displaced inwardly in the radial direction from the contact zone with the first punch, so that the pretreated second area is now arranged between the first punch and the third punch.
Due to the convex shape of the third punch, the second area is arranged in particular in a wall section of the third area extending substantially along the axial direction.
In particular, after step c) and after step c1), in a further step d), further forming of the base region takes place, wherein a wall section of the third region, extending at least along the axial direction, is formed outwardly in the radial direction in a fourth area.
This additional forming is carried out in particular to increase the dimensional stability of the base region, especially in view of high overpressures of a beverage container.
In particular, the fourth area at least partially comprises the second area. In particular, the fourth region is arranged at least along the axial and/or radial direction within the second region. In particular, the second region is arranged at least along the axial and/or radial direction within the fourth region.
In particular, the sheet material provided in step a) is in a flat state and, between steps a) and b), a sheet section is cut out of the sheet material in a step a3), so that in step c) the sheet section is deep-drawn and/or formed by stretch-slide drawing. Step a1) takes place before or after step a3). Step a2) is preferably carried out after step a3), but can in particular be carried out at least partially simultaneously with step a3).
A sheet material is further proposed. The sheet material has a width and a length which together span a planar surface having a material thickness. The sheet material includes on the planar surface a plurality of annular or annular-segment-shaped second areas having a reduced material thickness relative to the remainder of the surface.
In particular, the sheet material is designed to be suitable for the production of a container by the proposed method. In particular, the sheet material was already objected to the forming operations carried out in step a1). These (de-)formations forming the second areas can be produced, for example, by a pressing device, i.e. by at least one punch, or by a rolling device, in which a rolling tool is guided along the surface to form the second areas.
In particular, other processes can be used, but in any case the aim is to strain harden the second area, i.e. to locally increase the yield strength R_p0,2of the sheet material.
An apparatus for manufacturing a metallic container from a sheet material is further proposed. The apparatus is suitably designed for carrying out the described method or additionally for producing the described sheet material. The apparatus comprises at least a first punch for forming the sheet material at least by deep drawing and/or stretch-glide drawing, a holder for positioning the sheet material relative to the first punch, and a device for forming the sheet material in the second area, i.e. for reducing the material thickness and for increasing the yield strength R_p0,2of the sheet material in the second area.
A container is further proposed, made of a sheet material at least by deep drawing and/or stretch-glide drawing along an axial direction. The container comprises, at least at a first end, a base region at least partially closing the first end, adjoining the base region a wall region extending along the axial direction to a second end and formed circumferentially in a circumferential direction, and a lid region at least partially closing the second end.
The container is at least partially manufactured by the described method. Alternatively or additionally, the container is at least partially made from the described sheet material. Alternatively or additionally, the container is at least partially manufactured by the described apparatus.
The container is used in particular as a beverage container. As such, it comprises a housing with a base region, a lid region and a wall region connecting the base region to the lid region. In particular, the beverage container comprises a core bevel extending circumferentially in the circumferential direction (in the base region or) between the base region and the wall region, and possibly also a core bevel (in the lid region or) between the lid region and the wall region. The beverage container has a volume that is at least partially fillable or filled with a liquid. In the lid region and along a radial direction within the core bevel (if present), a closure is arranged in particular, via which the liquid can be removed from the volume in the open state.
The core bevel is in particular a groove in the base region (or lid region) which extends circumferentially in the circumferential direction and whose deepest point (along the axial direction) is formed in particular by the first punch. The groove comprises a width in the radial direction and a depth in the axial direction. The volume extends into the groove. The groove is bounded at its axial end (first end of the container) with respect to the radial direction by an inner wall (third area or fourth area of the container) extending circumferentially in the circumferential direction, and an outer wall extending circumferentially in the circumferential direction.
Beverage containers are regularly cylindrical in shape and therefore rotationally symmetrical about a central axis extending along the axial direction.
In particular, the beverage container is a beverage can.
In a closed initial state, the beverage container is in particular under a pressure, e.g. of at least 2.5 bar, which is greater than a pressure of an environment (in particular, the pressure of the environment is at most 1.1 bar).
The volume of the beverage container is in particular between 0.1 and 5 liters, preferably at most 3 liters, particularly preferably at most 1 liter.
The beverage container extends in particular from the base region to the lid region along an axial direction. The axial direction preferably runs parallel to the wall region. In particular, the beverage container is essentially cylindrical and (apart from structures e.g. in the lid region, e.g. for opening/closing the volume) has an axis of rotation or symmetry which extends parallel to the axial direction.
In particular, the comments on the method apply equally to the sheet material, the apparatus and the container, and the beverage container, and vice versa.
The use of indefinite articles (“a”, “an”), in particular in the claims and the description reproducing them, is to be understood as such and not as number words. Accordingly, terms or components introduced therewith are to be understood in such a way that they are present at least once and in particular, however, may also be present several times.
As a precaution, it should be noted that the number words used here (“first”, “second”, “third”, . . . ) primarily serve (only) to distinguish between several similar objects, variables or methods, i.e., in particular, they do not necessarily specify a dependency and/or sequence of these objects, variables or methods with respect to one another. If a dependency and/or sequence is required, this is explicitly stated here or it obviously results for the person skilled in the art when studying the specifically described embodiment.

The invention and the technical environment are explained in more detail below with reference to the figures. It should be noted that the invention is not intended to be limited by the embodiments shown. In particular, unless explicitly shown otherwise, it is also possible to extract partial aspects of the facts explained in the figures and combine them with other components and findings from the present description and/or figures. Identical reference signs designate identical objects, so that explanations from other figures can be used as a supplement if necessary. It shows schematically:

FIG. 1 : a container in a side view;

FIG. 2 : an apparatus and a sheet material in a plan view;

FIG. 3 : a side view of a method immediately after step a);

FIG. 4 : the method according to FIG. 3 immediately after step a3) and during step a2), in a side view;

FIG. 5 : the method according to FIGS. 3 and 4 immediately after steps a2) and a3), in a side view;

FIG. 6 : the process according to FIGS. 3 to 5 , wherein on the left step a1) is shown first, the state immediately after steps a2) and a3) is shown in the center, and the forming from the state immediately after step a2) to step c1) is shown on the right; in each case in a side view;

FIG. 7 : the workpiece according to FIG. 5 and a diagram;

FIG. 8 : the method during step b) and c) in a side view in section;

FIG. 9 : the method at the end of step c) in a side view in section;

FIG. 10 : the workpiece immediately before step c1) of the method in a side view in section and a diagram;

FIG. 11 : the workpiece immediately after step c1) of the method in a side view in section and a diagram; and

FIG. 12 : the workpiece after step d) of the method in a side view in section.

FIG. 1 shows a container 1 in a side view. The container 1 is made of a sheet material 2, at least by deep drawing and/or stretch-glide drawing along an axial direction 3. The container 1 comprises at a first end 4 a base region 5 closing the first end 4, adjoining this a wall region 8 extending along the axial direction 3 to a second end 6 and formed circumferentially in a circumferential direction 7, and a lid region 37 at least partially closing the second end 6.
The container 1 is at least partially (i.e. wall region 8 and base region 5) manufactured by the described method. Alternatively or additionally, the container 1 is at least partially (i.e. wall region 8 and base region 5) made of the described sheet material 2. Alternatively or additionally, the container 1 is at least partially (i.e. wall region 8 and base region 5) manufactured by the described apparatus 29.
The container 1 is used as a beverage container. The beverage container has a core bevel 38 extending circumferentially along the circumferential direction 7 (in the base region 5, respectively) between the base region 5 and the wall region 8. The beverage container has a volume 39 that is at least partially fillable or filled with a liquid. A closure can be arranged in the lid region 37, via which, for example, a liquid can be removed from the volume 39 in the open state.
The core bevel 38 is a groove in the base region 5, which extends circumferentially in the circumferential direction 7 and whose deepest point (along the axial direction 3) is formed by the first punch 10 (see FIGS. 8 and 9 ). The volume 39 extends into the groove. The groove is bounded at its axial end (first end 4 of the container 1) with respect to the radial direction 21 by an inner wall (third area 22 and fourth area 24 of the container 1, respectively) extending circumferentially in the circumferential direction 7, and an outer wall extending circumferentially in the circumferential direction 7.
The beverage container extends from the base region 5 to the lid region 37 along an axial direction 3. The axial direction 3 runs parallel to the wall region 8. The beverage container is essentially cylindrical and (apart from structures, e.g. in the lid region 37, e.g. for opening/closing the volume 39) has an axis of rotation or symmetry or a central axis 40 which extends parallel to the axial direction 3.
FIG. 2 shows a device 29 and a sheet material 2 in a plan view. The arrows indicate the feed direction 32 of the sheet material 2 through the device 29. The sheet material 2 provided in step a) is in a flat state. The sheet material 2 has a width (transverse to the feed direction 32 and to the travel path of the second punch 18) and a length (parallel to the feed direction 32), which together span a planar surface 26 with a material thickness/wall thickness 12 (in the direction of the travel path of the second punch 18).
The apparatus 29 is suitably designed for carrying out at least part of the described method and for producing the described sheet material 2. The apparatus 29 comprises a device 31 for forming the sheet material 2 in the second area 11, that is, for reducing the material thickness 12 and increasing the yield strength R_p0,2of the sheet material 2 in the second area 11. The apparatus 29 further comprises a plurality of second dies 18 for simultaneously forming the sheet material 2 at least by deep drawing in a plurality of sheet sections 25, and a holder 30 for positioning the sheet material 2 with respect to the second dies 18.
Between step a), i.e. the provision of the sheet material 2, and step a2), in which a contacting of the sheet material 2 with the second punches 18 and a subsequent deep drawing takes place, an at least partial forming of the sheet material 2 in the second area 11 is carried out in a step a1). The second area 11 comprises or at least partially covers an annular first area 9 of the sheet material 2, which is contacted by a first punch 10 in a subsequent step b) of the process (see FIGS. 8 and 9 ). A material thickness 12 of the sheet material 2 present in this second area 11 is reduced by the forming according to step a1) and thus at least a yield strength R_p0,2of the sheet material 2 is increased. The annular or annular-segment-shaped 30 second area 11 is bounded by a (smallest) second inner diameter 16 and a (largest) second outer diameter 17.
Before step a2), or at least partially simultaneously therewith, a sheet section 25 is cut out of the sheet material 2 in a step a3). Step a1) takes place before step a3).
Thus, before the second punches 18 act on the sheet material 2, the sheet material 2 already comprises, on the flat surface 26, a plurality of annular or annular-segment-shaped second areas 11 having a material thickness 12 reduced with respect to the rest of the surface 26. These deformations forming the second areas 11 can be produced, for example, by a pressing device, that is to say by at least one punch, or by a rolling device in which a rolling tool is guided along the surface 26 to form the second areas 11.
The respective generated second area 11 is annular-shaped or annular-segment-shaped. The annular-segment-shaped second area 11 (or the plurality of annular-segment-shaped second areas 11 arranged together within an imaginary annular-shaped second area 11) comprises an angular range 13 of together at least 180 angular degrees along a circumferential direction 7. The individual annular segment-shaped segments each extend over equal angular ranges 13.
The second areas 11 are circular annular-(segment-) shaped.
The sheet metal sections 25 formed in steps a1), a2) and a3) are then fed for further processing in steps b), c), c1) and d).
FIG. 3 shows a side view of a method immediately after step a). FIG. 4 shows the method according to FIG. 3 immediately after step a3) and during step a2), in a side view. FIG. 5 shows the method according to FIGS. 3 and 4 immediately after steps a2) and a3), in a side view. FIGS. 3 to 5 are described together below. Reference is made to the explanations of FIGS. 1 and 2 .
FIG. 3 shows a part of the apparatus 29 with a second punch 18. The apparatus 29 is designed for at least partially simultaneous execution of steps a2) and a3), i.e. for cutting out a sheet section 25 from the sheet material 2 according to step a3) and for contacting the sheet material 2 with the second punch 18 and subsequent deep drawing according to step a2). In FIG. 3 , the second punch 18 is moved along the axial direction 3 towards the sheet material 2. In FIG. 4 , step a3) has already been carried out and the sheet section 25 now present is contacted by the second punch 18 and deep-drawn. In FIG. 5 , step a2) is completed and the second punch 18 is moved back to its starting position.
As in the known manufacture of a container 1, a (circular or contoured) sheet section 25 is first cut out of a flat continuous sheet material 2 and (immediately) thereafter formed. This forming comprises deep drawing, wherein a second punch 18 forms the sheet material 2 or the sheet section 25 into a cup-like container 1. This forming into the cup-like container 1 is carried out before step b) in step a2).
FIG. 6 shows the method according to FIGS. 3 to 5 , with step a1) shown on the left first, in the center the state immediately after steps a2) and a3) (see also FIG. 5 ), and the transformation from the state immediately after step a2) to step c1) on the right; in each case in a side view. Reference is made to the explanations of FIGS. 1 to 5 .
According to step a), the sheet material 2 is provided (see left figure of FIG. 6 ). According to step b), the sheet material 2 is contacted in an annular first area 9 with a first punch 10 (see right figure of FIG. 6 ) and according to step c), the sheet material 2 is subsequently deep-drawn and/or extruded to form the base region 5 and the wall region 8 (see FIGS. 8 and 9 ). Between steps a) and b), in a step a1), an at least partial forming of the sheet material 2 takes place in a second area 11 (see left-hand figure of FIG. 6 ), the second area 11 at least partially comprising the first area 9. A material thickness 12 of the sheet material 2 present in this second area 11 is reduced by the forming and thus at least one yield strength R_p0,2of the sheet material 2 is increased.
The center image of FIG. 6 shows that a circular sheet section 25 is cut out of the flat sheet material 2 and immediately thereafter formed. This forming comprises deep drawing, wherein a second punch 18 forms the sheet material 2 or the sheet section 25 into a cup-like container 1. This forming into the cup-like container 1 is carried out before step b) in step a2).
After step a2), the cup-like container 1 is fed to a further forming station in which the cup-like container 1 is further formed by deep drawing and/or stretch-glide drawing (step c). In step b), a first punch 10, which can be moved along the axial direction 3, strikes the base region 5 of the cup-like container 1 and, in step c), draws the sheet material 2 through a die (see FIGS. 8 and 9 ). In this process, the base region 5 and the wall region 8 of the container 1 are at least partially formed. As a result of the impact of the first punch 10 on the base region 5 of the cup-like container 1, the sheet material 2 is locally damaged in the first area 9 in which the first punch 10 contacts the sheet material 2 for the first time (if no preforming has taken place according to step a1)) and the material thickness 12 is locally reduced.
In further forming processes, in particular of the base region 5, this damage can be displaced, e.g. in a radial direction 21 further inwards (see arrow in the right picture of FIG. 6 ). Thereby, just this damaged area can be subject to further forming, if necessary, so that further damage or even failure of the sheet material 2 can occur. In particular, the locally reduced material thickness 12 is further reduced in the course of further forming, so that a material thickness 12 which is too thin for the intended application of the container 1 results or may result.
Pretreatment of the first area 9 can result in reducing or preventing damage as a result of contacting the first punch 10 and, if necessary, at least reducing or completely suppressing further damage as a result of further forming.
This is achieved in that in step a1) the sheet material 2 is at least partially formed in a second area 11, the second area 11 at least partially or (as shown here) completely enclosing or covering the first area 9. A material thickness 12 of the sheet material 2 present in this second region 11 is reduced by the forming and thus at least one yield strength R_p0,2of the sheet material 2 is increased.
This increase in the yield strength and/or the strain hardening of the sheet material 2 achieved by the forming process means that the impact of the first punch 10 causes only a smaller deformation of the first area 9. It is further achieved that the sheet material 2 present in this second area 11 is not further deformed or is only further deformed to a lesser extent in further forming operations due to the strain hardening. In particular, during the forming of adjacent areas, there is a greatly reduced or even no subsequent flow of sheet material 2 from this second area 11, but only from other areas. This prevents (or largely reduces) any further reduction in material thickness 12 occurring in this second area 11.
The first area 9 is circular-annular in shape and corresponds to the contact surface or impact surface of the first punch 10 on the sheet material 2. The second area 11 is arranged coaxially with the first area 9.
The annular first area 9 is bounded by a (smallest) first inner diameter 14 and a (largest) first outer diameter 15. The annular or annular segment-shaped second area 11 is bounded by a (smallest) second inner diameter 16 and a (largest) second outer diameter 17. The second inner diameter 16 is smaller than the first inner diameter 14.
Each inner diameter 14, 16 is parallel to and coaxial with the outer diameter 15, 17 of the same area 9, 11. All diameters 14, 15, 16, 17 are arranged coaxially with each other. The second outer diameter 17 is larger than the first outer diameter 15.
Between steps a) and b), the sheet material 2 is brought into contact with a second punch 18 and subsequently deep-drawn in step a2). The second punch 18 has a larger punch outer diameter 19 than the first punch 10.
FIG. 7 shows the workpiece, the cup-like container 1, according to FIG. 5 and a diagram. Reference is made to the explanations of FIGS. 1 to 6 .
This forming into the cup-like container 1 is carried out before step b) in step a2) with the second punch 18.
On the horizontal axis of the diagram is plotted the distance 33 of the points of the surface of the container 1 along the surface from the central axis 40 of the container 1. On the vertical axis, the material thickness 12 of the container 1 is plotted in millimeters.
It can be seen that the material thickness 12 in the base region 5 is relatively constant at 242 μm. In the area of the punch outer diameter 19 of the second punch 18 there is a minimum of the material thickness at approx. 235 μm. The part of the sheet section 25 extending along the axial direction 3 has an increasing material thickness 12 along the axial direction 3, here up to approx. 300 μm.
FIG. 8 shows the method during step b) and c) in a side view in section. FIG. 9 shows the method at the end of step c) in a side view in section. FIGS. 8 and 9 are described together below. Reference is made to the explanations of FIGS. 1 to 7 .
The cup-like container 1, which is present according to steps a1), a2) and a3), is arranged in an apparatus 29. This apparatus 29 comprises a holding-down device 41, a support 42 and a first punch 10. According to step b), the cup-like container 1 is brought into contact in an annular first area 9 with the first punch 10 (see also right-hand figure of FIG. 6 ) and, according to step c), the cup-like container 1 is subsequently deep-drawn and/or extruded to form the base region 5 and the wall region 8. In step b), a first punch 10, which is movable along the axial direction 3, strikes the base region 5 of the cup-like container 1 and draws the sheet material 2 successively through a die or an opening of the support 42 in step c). In this process, the base region 5 and the wall region 8 of the container 1 are at least partially formed. As a result of the impact of the first punch 10 on the base region of the cup-like container 1, the material thickness 12 of the sheet material 2 is locally reduced in the first area 9 in which the first punch 10 contacts the sheet material 2 for the first time. As a result of carrying out step a1), i.e. forming the second area 11, the reduction in the material thickness 12 due to the impact of the first punch 10 is now less.
Starting from the position of the first punch 10 according to FIG. 9 , a further forming of the bottom area 5 by a third punch 20 (see FIG. 11 ), which may be arranged immovably, e.g. by a further movement of the first punch 10 along the axial direction 3, can take place during or subsequently to step c) in a step c1).
A third area 22 of the sheet material 2 arranged inside the hollow-cylindrical first punch 10, as seen in a radial direction 21, is formed by the third punch 20 along the axial direction 3 toward the second end 6 (see FIG. 11 ).
The first punch 10 is designed as a hollow punch, with the third punch 20 entering at least partially into a hollow section of the first punch 10 along the axial direction 3 at the end of step c1). The third punch 20 has a convex contact surface relative to the base region 5, so that a concave shape as seen from the outside is formed in the base region 5 (see FIG. 11 ).
After step c) and after step c1), a further forming of the base region 5 is carried out in a further step d), wherein a wall section 23 of the third area 22 extending at least along the axial direction 3 is formed in the radial direction 21 outwardly in a fourth area 24 (see FIG. 12 ).
The following FIGS. 10 to 12 illustrate the problems of the prior art. FIGS. 10 to 12 are also used to explain the advantages now achieved.
FIG. 10 shows the workpiece immediately before step c1) of the method in a side view in section and a diagram (see also shape of the base region 5 of the container 1 in FIG. 9 ). Reference is made to the explanations of FIGS. 1 to 9 .
On the left side of FIG. 10 , the course of the wall of the container 1 from the center axis 40 is shown. Measuring points are distributed along the wall.
On the horizontal axis of the diagram the measurement points and the distance 33 are shown. The distance 33 denotes the distance of a point of the surface of the container 1 from the center axis 40 along the surface of the container 1. On the vertical axis the material thickness 12 of the sheet material 2 of the container 1 is shown. In the diagram, three courses 34, 35, 36 of the material thickness 12 of the sheet material 2 are shown over distances 33 and over the measurement points, respectively.
The first course 34 connects the maxima of the material thicknesses 12 measured on a plurality of containers 1. The second course 35 connects the mean values of the material thicknesses 12 measured on a plurality of containers 1. The third course 36 connects the minima of the material thicknesses 12 measured on a plurality of containers 1. It can be seen that the courses 34, 35, 36 each have a minimum that lies in the range of the measuring points “10” to “12”. These measuring points “10” and “12” are located in the first area 9, which is circular in shape and corresponds to the contact surface or the impact surface of the first punch 10 on the sheet material 2 in step b). Values of the material thickness 12 of up to 222 μm are achieved.
These low values of the material thickness 12 can be raised by pretreating the sheet material 2 according to step a1) of the process. A second area 11 created in this way then extends over the first area 9 shown here.
FIG. 11 shows the workpiece immediately after step c1) of the method in a side view in section and a diagram (see also right picture of FIG. 6 ). Reference is made to the explanations of FIGS. 1 to 10 .
On the left side of FIG. 11 , the course of the wall of the container 1 from the center axis 40 is shown. Measuring points are distributed along the wall.
On the horizontal axis of the diagram the measurement points and the distance 33 are shown. The distance 33 denotes the distance of a point of the surface of the container 1 from the center axis 40 along the surface of the container 1. On the vertical axis the material thickness 12 of the sheet material 2 of the container 1 is shown. In the diagram, three courses 34, 35, 36 of the material thickness 12 of the sheet material 2 are shown over distances 33 and over the measurement points, respectively.
The first course 34 connects the maxima of the material thicknesses 12 measured on a plurality of containers 1. The second course 35 connects the mean values of the material thicknesses 12 measured on a plurality of containers 1. The third course 36 connects the minima of the material thicknesses 12 measured on a plurality of containers 1. It can be seen that the courses 34, 35, 36 each have a minimum that lies in the range of the measuring points “10” to “12”.
A third area 22 of the sheet material 2 arranged inside the hollow-cylindrical first punch 10, as seen in a radial direction 21, is formed by the third punch 20 along the axial direction 3 toward the second end 6. The first punch 10 is designed as a hollow punch, with the third punch 20 entering at least partially into a hollow section of the first punch 10 along the axial direction 3 towards the end of step c1). The third punch 20 has a convex contact surface relative to the base region 5, so that a concave shape as seen from the outside is formed in the base region 5.
As a result of this, starting from the shape of the container 1 according to FIG. 10 , further forming of the base region 5 according to step c1), the first area 9 (and in the case of pretreatment correspondingly the second area 11) is displaced inwards in the radial direction 21, so that after the further forming the first area 9 (or the second area 11; or the measuring points 10, 12 of FIG. 10 ) is arranged along the radial direction 21 between the first punch 9 and the third punch 20.
Due to the convex shape of the third punch 20, the first area 9 (or the second area 11) arranges itself in a wall section 23 of the third area 22 extending substantially along the axial direction 3.
The forming of the base region 5 according to step c1) leads to a further increase in the surface area of the sheet material 2 in the base region 5. As a result, the material thickness 12 in the base region 5 is further reduced (see courses 34, 35, 36 of the diagrams in FIGS. 10 and 11 ).
The displacement of the first area 9 into the further formed base region 5 and the further reduction in material thickness 12 resulting as a consequence of the further forming mean that values of material thickness 12 of up to 218 μm are now achieved (i.e. without pretreatment according to step a1)).
In further forming processes of the base region 5, this damage to the first area 9 can thus be shifted further inwards in a radial direction 21. In this case, it is precisely this damaged area 9 that can be the subject of further forming, in this case according to step c1), so that further damage or even failure of the material can occur. In particular, the locally reduced material thickness 12 is further reduced in the course of further forming, resulting in a material thickness 12 that is too thin for the intended use of the container 1.
The second area 11 (namely the area of the measuring points “10” to “12”) resulting from a pretreatment according to step a1) and extending over the first area 9 will be located between the first punch 10 and the third punch 20, as described above for the first area 9.
Pretreatment of the first area 9 as part of step a1) can result in damage as a result of contacting the first punch 10 being reduced or prevented, and thus further damage as a result of further forming can be at least reduced or completely suppressed.
FIG. 12 shows a sectional side view of the workpiece after step d) of the method. Reference is made to the explanations of FIGS. 10 and 11 .
After step c) and after step c1), a further forming of the base region 5 is carried out in a further step d), wherein a wall section 23 of the third area 22 extending at least along the axial direction 3 is formed outwardly in a fourth area 24 in the radial direction 21. This additional forming is carried out in particular to increase the dimensional stability of the base region 5, especially in view of high overpressures of a beverage container.
This fourth area 24 includes the first area 9 and, precisely because of this, can lead to material failure of the pre-damaged sheet material 2, which is further reduced in material thickness 12.
The pretreatment of the first region 9 as part of step a1) can result in the fourth area 24 now comprising the pretreated second area 11, so that further damage as a result of further forming can be at least reduced or completely suppressed.
This increase in the yield strength and/or the strain hardening of the sheet material 2 achieved by the forming as a result of carrying out step a1) means that the impact of the first punch 10 causes only a smaller deformation of the first area 9. Further, it is achieved that the sheet material 2 present in this second area 11 is not further deformed or is only further deformed to a lesser extent in further forming operations due to the solidification. In particular, there is no subsequent flow of sheet material 2 from this second area 11 during the forming of adjacent areas, but from other areas. This prevents a further reduction in material thickness 12 from occurring in this second area 11.

LIST OF REFERENCE SIGNS

- 1 container
- 2 sheet material
- 3 axial direction
- 4 first end
- 5 base region
- 6 second end
- 7 circumferential direction
- 8 wall region
- 9 first area
- 10 first punch
- 11 second area
- 12 material thickness/wall thickness
- 13 angle range
- 14 first inner diameter
- 15 first outer diameter
- 16 second inner diameter
- 17 second outer diameter
- 18 second punch
- 19 punch outer diameter
- 20 third punch
- 21 radial direction
- 22 third area
- 23 wall section
- 24 fourth area
- 25 sheet metal section
- 26 surface
- 27 width
- 28 length
- 29 apparatus
- 30 holder
- 31 device
- 32 feed direction
- 33 distance
- 34 first course
- 35 second course
- 36 third course
- 37 lid region
- 38 core bevel
- 39 volume
- 40 center axis
- 41 holding-down device
- 42 support

Claims

1. A method for producing a metallic container from a sheet metal material, the metallic container comprising, at a first end, a base region which at least partially closes the first end and, adjacent to the base region, a wall region which extends along an axial direction towards a second end and is formed circumferentially in a circumferential direction, the method comprising:

partially forming the sheet metal material in a second area along the axial direction, wherein the second area at least partially comprises an annular first area;

contacting the sheet metal material in the annular first area with a first punch; and

deep drawing and/or stretch-glide drawing the sheet metal material to form the base region and the wall region along the axial direction;

wherein a material thickness of the sheet metal material in the second area is reduced by the partial forming thus increasing at least one yield strength R_p0,2of the sheet metal material.

2. The method of claim 1, wherein the second area is annular or annular-segment-shaped; and

wherein the second area comprises an angular range of at least 180 angular degrees along the circumferential direction.

3. The method of claim 1, wherein the annular first area is bounded by a first inner diameter and a first outer diameter;

wherein the second area is bounded by a second inner diameter and a second outer diameter; and

wherein the second inner diameter is smaller than the first inner diameter.

4. The method of claim 3, wherein the second outer diameter is larger than the first outer diameter.

5. The method of claim 1, further comprising:

contacting the sheet metal material with a second punch; and

deep drawing the sheet metal material with the second punch;

wherein the second punch has a larger punch outer diameter than the first punch.

6. The method of claim 5, wherein contacting the sheet metal material with the second punch and deep drawing the sheet metal material with the second punch occurs after partially forming the sheet metal material in the second area along the axial direction.

7. The method of claim 1, wherein

partially forming the sheet metal material in the second area along the axial direction reduces the material thickness in the second area by at least 3% and a yield strength R_p0,2of the second area is increased by at least 5%.

8. The method of claim 1, wherein deep drawing and/or stretch-glide drawing the sheet metal material to form the base region and the wall region along the axial direction is carried out at least partly with the first punch, the method further comprising further forming of the base region by a third punch,

wherein a third area of the sheet metal material arranged within the first punch with regard to a radial direction is formed by the third punch along the axial direction towards the second end.

9. The method of claim 8, wherein, the second area is displaced inwardly in the radial direction so that, after the further forming, the second area is arranged along the radial direction between the first punch and the third punch.

10. The method of claim 8, wherein a wall section of the third area, extending at least along the axial direction, is formed outwardly in the radial direction in a fourth area.

11. The method of claim 10, wherein the fourth area at least partially comprises the second area.

12. The method of claim 1, wherein the method further comprises, before or after partially forming the sheet metal material in the second area along the axial direction, cutting out a sheet section of the sheet metal material, wherein the sheet section is deep-drawn and/or stretch-glide-drawn.

13. A sheet metal material comprising a width forming a planar surface and a length and a material thickness;

wherein the planar surface comprises a plurality of annular or annular-segment-shaped second areas having a second area material thickness reduced with respect to the planar surface.

14. An apparatus for producing a metallic container from a sheet metal material, the apparatus comprising:

a first punch configured to form the sheet metal material at least by deep drawing and/or stretch-glide drawing in a first area,

a holder configured to position the sheet metal material relative to the first punch, and

a device configured to form and/or reduce a material thickness of the sheet metal material in a second area.

15. A container produced by the method of claim 1, the container comprising:

at a first end, a base region at least partially closing the first end,

adjoining the base region, a wall region extending along an axial direction to a second end and formed circumferentially in a circumferential direction, and

a lid region at least partially closing the second end.

16. The apparatus of claim 14, wherein:

the device configured to form and/or reduce the material thickness of the sheet metal material in the second area comprises a second punch;

the second punch is located along an axial direction from the first punch; and

the second punch is configured to deep draw the sheet metal material in the second area.

17. The apparatus of claim 16, wherein the second punch has a larger punch outer diameter than the first punch.

18. The apparatus of claim 14, further comprising a third punch located along a radial direction from the first punch, wherein the third punch is configured to form and/or reduce the material thickness of the sheet metal material in the second area such that the second area is arranged along the radial direction between the first punch and the third punch; and

wherein the third punch is configured to deep draw a third area.

19. The apparatus of claim 18, further comprising a second device configured to form a fourth area that extends at least along an axial direction radially outward from the third area.

20. The apparatus of claim 14, further comprising a third device configured to cut a sheet section from the sheet metal material.