METHOD FOR MANUFACTURING A METAL CONTAINER

Description

[0001] The present invention relates to a method for manufacturing a metallic container from sheet metal. The container is, in particular, part of a can, especially a beverage can. The can consists, in particular, of at least two parts: firstly, the container itself, and secondly, a lid section that is connected to the container, e.g., by a folded seam.

[0002] The container is manufactured at least by deep drawing or stretch drawing along an axial direction. The container has a bottom section at a first end that at least partially, and in particular completely, closes the first end, and adjoining this, a circumferential wall section extending along the axial direction to a second end.

[0003] A lid or lid section can be attached to the second end. The lid can, in particular, have a closure through which the contents of the container sealed by the lid can be removed.

[0004] The container can be, for example, part of a beverage container, in particular a (metallic) beverage can. The beverage container serves to store a contents, e.g., a liquid, whereby the beverage container, in its closed state (initial state), can be under an overpressure relative to the surroundings or relative to atmospheric pressure of approximately 1 bar.

[0005] The known two-part containers or cans, closed by a lid, have a base section that determines the container's volume, followed by a cylindrical wall section. These sections are manufactured as a single unit in one operation – i.e., as a single piece – by deep drawing and / or die drawing. The wall thickness of the wall section in these containers is, for example, on the order of approximately 0.080 mm to approximately 0.160 mm, with the greatest thickness in the area where the lid will later be attached, while the wall thickness of the base section is on the order of approximately 0.220 mm to approximately 0.350 mm. A lid can be positioned on the side of the (appropriately prepared) wall section opposite the base section. The lid is attached to the wall section of the can in the usual manner, for example, by means of a so-called double fold. The wall thickness of the lid is in particular on the order of 0.180 mm to approximately 0.230 mm.

[0006] Containers of this type are used in considerable quantities, particularly for beverages of all kinds, as single-use packaging, with a large proportion of the can material being made from recycled material. Considering the large market volume, a significant amount of material (especially tinplate or aluminum) is required. Even relatively small amounts of material that could be saved in the production of a single container would, in relation to the total annual consumption of approximately five billion cans in Germany alone, represent a considerable and certainly not negligible material saving.

[0007] Especially with beverage cans containing carbonated liquids, the container can be under an internal pressure of up to 6.2 bar before being opened for the first time. For this reason, a dimensionally stable design with sufficient wall thickness is essential for the base.

[0008] Any reduction in the material required for a container has a significant impact due to the large production volume, particularly regarding material costs. For this reason, there is a constant need to progressively reduce the container wall thickness. However, further reduction of the wall thickness carries the risk of material failure, especially during the additional forming processes sometimes required for the bottom area and / or due to the maximum pressure load.

[0009] For example, US 2013 / 0037554 A1, which forms the basis for the preamble of claim 1, discloses a method for manufacturing a container with a flat bottom.

[0010] From WO 2020 / 158355 A1 a method for manufacturing a beverage can is known in which the bottom area of ​​the can, especially in the area of ​​the lower core slope, is intended to have a deliberately greater wall thickness than the starting material.

[0011] US patent 4,722,215 A is directed at a tool for manufacturing a beverage can.

[0012] The object of the invention is therefore to at least partially solve the problems existing with regard to the prior art and in particular to provide a method for manufacturing a container by which a reproducible quality of thin-walled containers made from the thinnest possible starting material can be ensured.

[0013] These problems are solved by a method according to the features of claim 1. Further advantageous embodiments are specified in the dependent claims. In addition, the features specified in the claims are further specified and explained in the description, and further preferred embodiments of the invention are presented.

[0014] A method for manufacturing a metallic container from a sheet metal material according to claim 1 is proposed.

[0015] In the known method of manufacturing a container, a (circular) sheet metal section is first cut from a continuous, flat material and then immediately formed. This forming process initially includes, in particular, deep drawing, whereby a (second) punch, which is movable, especially along the axial direction, forms the sheet metal material or the sheet metal section into a cup-shaped container. The cup-shaped container is then fed to a further forming station, in which it is further formed by deep drawing and / or stretch drawing. In particular, a first punch, which is movable, especially along the axial direction, strikes the bottom region of the cup-shaped container and draws the sheet metal material through a (possibly multi-stage) die. The bottom and wall regions of the container are thereby at least partially formed, especially by stretch drawing.However, as a result of the first punch striking the bottom area of ​​the cup-shaped container, the sheet metal material is locally damaged in the first area where the first punch first contacts the sheet metal material, and the wall thickness is locally reduced.

[0016] In further forming processes, particularly of the base area, this damage can be displaced further inwards, for example, in a radial direction. This damaged area may then be subject to further forming, potentially leading to further damage, a critical weak point, or even material failure. Specifically, the locally reduced wall thickness is further reduced during subsequent forming processes, resulting in a wall thickness that is insufficient for the intended application of the container.

[0017] Pretreatment of the first area can reduce or prevent damage resulting from contact with the first punch and may at least reduce or completely suppress further damage resulting from further forming.

[0018] In the present case, this is achieved in particular by the fact that in step a1) at least a partial forming of the sheet metal material takes place in a second area, wherein the second area at least partially or completely encompasses the first area. The material thickness of the sheet metal present in this second area is reduced by the forming and thus at least one yield strength R p0,2 of the sheet metal material is increased.

[0019] This increase in the yield strength and / or the work hardening of the sheet metal achieved through forming results in only minimal deformation of the first area upon impact of the first punch. Furthermore, the work hardening prevents the sheet metal in this second area from deforming further, or at least reduces its deformation, during subsequent forming operations. Specifically, when forming adjacent areas, the sheet metal material does not flow from this second area, but rather from other areas. This prevents further reduction in material thickness in this second area.

[0020] In particular, a deliberate reduction in material thickness in the second area (and the associated strengthening of the sheet material) prevents or reduces a subsequent further reduction in material thickness.

[0021] This allows sheet metal materials with lower material thicknesses to be used for the production of containers, without material failure occurring during the manufacture of the container or during the later predetermined use of the container.

[0022] In particular, the second region is ring-shaped or ring-segment shaped. Specifically, the ring-segment shaped second region (or a plurality of ring-segment shaped second regions arranged together within an imaginary ring-shaped second region) encompasses an angular range of (total) at least 180 degrees, and in particular at least 270 degrees, along a circumferential direction. In particular, the individual ring-shaped segments extend over equal, but possibly also different, angular ranges, e.g., at least 5 degrees or at least 25 degrees each.

[0023] In particular, the second area is shaped like a ring (or segment).

[0024] In particular, the first area is circular in shape and corresponds (especially at least) to the contact surface or the impact surface of the first punch on the sheet metal material.

[0025] In particular, the second area is arranged coaxially to the first area.

[0026] In particular, the annular first region is bounded by a (smallest) first inner diameter and a (largest) first outer diameter. In particular, the annular or ring-segment-shaped second region 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.

[0027] In particular, each inner diameter runs parallel to the outer diameter of the same area and is arranged coaxially to it.

[0028] In particular, a second inner diameter runs parallel to the first inner diameter and is arranged coaxially to it.

[0029] In particular, the second outer diameter is larger than the first outer diameter.

[0030] The initial diameters are determined, particularly on the flat, undeformed sheet metal section or the sheet material itself, e.g., also using the first die. The second diameters can then be determined and specified based on the initial diameters.

[0031] In particular, between steps a) and b), in step a2), the sheet metal material is contacted with a second punch and subsequently deep-drawn. The second punch has a larger outer diameter than the first punch.

[0032] As explained above, in the known manufacturing process for a container, a (circular) sheet metal section is first cut from a continuous, flat material and then (immediately) formed. This forming process initially includes, in particular, deep drawing, whereby a second die shapes the sheet metal material or the sheet metal section into a cup-shaped container. This forming into the cup-shaped container is carried out, in particular, before step b) in step a2).

[0033] In particular, step a2) occurs after step a1), i.e., it is carried out afterwards. However, step a1) can also occur after step a2) but before step b).

[0034] 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 p0.2 is increased by at least 5%, preferably at least 10%, particularly preferably at least 15% or even at least 17%.

[0035] In experiments, a reduction in material thickness in the second area of ​​an aluminum alloy from 245 µm [micrometers] to 230 µm (i.e. a reduction of 6.1%) was observed, along with a work hardening from a yield strength R p0,2 of 276 MPa [megapascals] to 325 MPa (i.e. an increase of 17.75%).

[0036] In particular, step c) is at least partially carried out with the first punch, wherein, during or following step c), a further forming of the bottom area is performed in step c1) by a third punch, which may be arranged in a fixed position. A third area of ​​the sheet material arranged within the first punch relative to a radial direction is formed by the third punch along the axial direction towards the second end.

[0037] 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 at the end of step c1). Specifically, the third punch has a convex contact surface relative to the bottom region, so that a concave shape is formed in the bottom region when viewed from the outside.

[0038] In particular, as a result of the further forming of the bottom area according to step c1), the second area is shifted inwards 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.

[0039] The forming of the bottom area according to step c1) leads in particular to a further increase in the surface area of ​​the sheet metal material in the bottom area. This further reduces the material thickness in the bottom area. In particular, sheet metal material from adjacent areas is also displaced radially inwards as a result of the forming process.

[0040] In particular, the second area is also shifted inwards in the radial direction from the contact zone with the first punch, so that the pre-treated second area is now positioned between the first punch and the third punch.

[0041] Due to the convex shape of the third punch, the second area is arranged in particular in a wall section of the third area that extends essentially along the axial direction.

[0042] In particular, after step c) and after step c1), in a further step d) the bottom area is further reshaped, wherein a wall section of the third area extending at least along the axial direction is reshaped outwards in a fourth area in the radial direction.

[0043] This additional forming process is carried out in particular to increase the dimensional stability of the bottom area, especially against the high overpressures of a beverage container.

[0044] In particular, the fourth region at least partially encompasses the second region. Specifically, the fourth region is arranged within the second region at least along the axial and / or radial direction. Specifically, the second region is arranged within the fourth region at least along the axial and / or radial direction.

[0045] In particular, the sheet metal material provided in step a) is in a flat state, and between steps a) and b), a sheet metal section is cut out of the sheet metal material in step a3), so that in step c) the sheet metal section is deep-drawn and / or formed by stretch drawing. Step a1) is performed before or after step a3). Step a2) is preferably performed after step a3), and can in particular be carried out at least partially simultaneously with step a3).

[0046] A sheet metal material is further described which is relevant for understanding the invention but is not part of the invention itself. The sheet metal material has a width and a length which together span a flat surface with a material thickness. On this flat surface, the sheet metal material comprises a plurality of annular or ring-segment-shaped second regions which have a reduced material thickness compared to the remaining surface.

[0047] The sheet metal material is particularly suitable for manufacturing a container using the proposed method. In particular, the sheet metal material already exhibits the forming operations carried out in step a1). These forming operations, which create the second areas, can be performed, for example, by a press, i.e., by at least one punch, or by a rolling machine in which a rolling tool is guided along the surface to form the second areas.

[0048] In particular, other methods can also be used, whereby in any case the strengthening of the second area, i.e. the local increase of the yield strength R p0,2 of the sheet material, should be achieved.

[0049] Furthermore, a device for manufacturing a metallic container from sheet metal according to claim 13 is proposed. The device can additionally be configured to manufacture the described sheet metal material.

[0050] A container is further described which is relevant for understanding the invention but is not part of the invention itself. The container is made of sheet metal material, at least by deep drawing and / or drawing-slide forming along an axial direction. The container comprises, at least at a first end, a bottom section that at least partially closes the first end, followed by a wall section extending axially to a second end and forming a circumferential wall, and a lid section that at least partially closes the second end.

[0051] The container is manufactured at least partially by the described method. Alternatively or additionally, the container is manufactured at least partially from the described sheet metal material. Alternatively or additionally, the container is manufactured at least partially using the described device.

[0052] The container is used primarily as a beverage container. As such, it comprises a housing with a base, a lid, and a wall connecting the base and lid. Specifically, the beverage container has a core slope extending circumferentially (in the base) between the base and the wall, and optionally an additional core slope (in the lid) between the lid and the wall. The beverage container has a volume that is at least partially fillable with a liquid. A closure is provided in the lid and along a radial direction within the core slope (if present), allowing liquid to be dispensed from the volume when open.

[0053] The core chamfer is, in particular, a circumferential groove in the bottom (or lid) area, the deepest point of which (along the axial direction) is formed, in particular, by the first punch. The groove has a width in the radial direction and a depth in the axial direction. The volume extends into the groove. At its axial end (first end of the container), the groove is bounded, relative to the radial direction, by a circumferential inner wall (third or fourth area of ​​the container) and a circumferential outer wall.

[0054] Beverage containers are regularly cylindrical in shape and therefore rotationally symmetrical about a central axis that extends along the axial direction.

[0055] The beverage container is, in particular, a beverage can.

[0056] The beverage container is in a sealed initial state, in particular under a pressure, e.g. of at least 2.5 bar, which is greater than the pressure of the surroundings (in particular the pressure of the surroundings is at most 1.1 bar).

[0057] The volume of the beverage container is in particular between 0.1 and 5 liters, preferably at most 3 liters, and most preferably at most 1 liter.

[0058] The beverage container extends, in particular, from the base to the lid along an axial direction. This axial direction preferably runs parallel to the wall. Specifically, the beverage container is essentially cylindrical and (apart from structures, e.g., in the lid area, for opening / closing the volume) has an axis of rotation or symmetry that extends parallel to the axial direction.

[0059] The descriptions of the process apply equally to the sheet metal material, the device and the container as well as the beverage container, and vice versa.

[0060] The use of indefinite articles ("a", "an", "a" and "one"), particularly in the patent claims and the description reproducing them, is to be understood as such and not as a numeral. Accordingly, terms or components introduced by these articles are to be understood as occurring at least once and, in particular, may also occur multiple times.

[0061] It should be noted as a precaution that the numerical terms used here ("first", "second", "third", ...) primarily serve (only) to distinguish between several similar objects, quantities, or processes, and thus do not necessarily dictate any dependency and / or sequence between these objects, quantities, or processes. Should a dependency and / or sequence be required, this is explicitly stated here, or it will be obvious to a person skilled in the art upon studying the specific configuration described.

[0062] The invention and its technical context are explained in more detail below with reference to the figures. It should be noted that the invention is not limited to the embodiments shown. The same reference numerals denote the same objects, so that explanations from other figures may be consulted as needed. The figures schematically show: Fig. 1: a container in a side view; Fig. 2: a device and sheet metal material in a top view; Fig. 3: a method immediately after step a) in a side view; 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 method according to Figs. 3 to 5 , where on the left is step a1), in the middle the state immediately after steps a2) and a3), and on the right the transformation from the state immediately after step a2) to step c1); each in a side view; Fig. 7: the workpiece according to Fig. 5and a diagram; Fig. 8: the process during steps b) and c) in a side view in section; Fig. 9: the process at the end of step c) in a side view in section; Fig. 10: the workpiece immediately before step c1) of the process in a side view in section and a diagram; Fig. 11: the workpiece immediately after step c1) of the process in a side view in section and a diagram; and Fig. 12: the workpiece after step d) of the process in a side view in section.

[0063] Fig. 1Figure 1 shows a container 1 in a side view. The container 1 is made of sheet metal material 2, at least by deep drawing and / or stretch drawing along an axial direction 3. The container 1 comprises a bottom section 5 at a first end 4, which closes the first end 4; a wall section 8 extending along the axial direction 3 to a second end 6 and forming a circumferential band 7; and a lid section 37 that at least partially closes the second end 6.

[0064] Container 1 is manufactured at least partially (i.e., wall region 8 and bottom region 5) by the described method. Alternatively or additionally, container 1 is manufactured at least partially (i.e., wall region 8 and bottom region 5) from the described sheet metal material 2. Alternatively or additionally, container 1 is manufactured at least partially (i.e., wall region 8 and bottom region 5) using the described device 29.

[0065] Container 1 is used as a beverage container. The beverage container has a core slope 38 running along the circumferential direction 7 (in the base region 5) between the base region 5 and the wall region 8. The beverage container has a volume 39, which can be filled with a liquid or is already filled. A closure can be arranged in the lid region 37, through which, when open, a liquid can be removed from the volume 39.

[0066] The core slope 38 is a groove extending circumferentially in the circumferential direction 7 in the base area 5, the lowest point of which (along the axial direction 3) is formed by the first punch 10 (see Figs. 8 and 9 ) is formed. The volume 39 extends into the groove. The groove is bounded at its axial end (first end 4 of the container 1) opposite the radial direction 21 by an inner wall circumferentially 7 (third region 22 or fourth region 24 of the container 1), and an outer wall circumferentially 7.

[0067] The beverage container extends from the base area 5 to the lid area 37 along an axial direction 3. The axial direction 3 runs parallel to the wall area 8. The beverage container is essentially cylindrical and has (apart from structures e.g. in the lid area 37, e.g. for opening / closing the volume 39) an axis of rotation or axis of symmetry or a central axis 40, which extends parallel to the axial direction 3.

[0068] Fig. 2Figure 1 shows a device 29 and a sheet metal material 2 in a top view. The arrows indicate the feed direction 32 of the sheet metal material 2 through the device 29. The sheet metal material 2 provided in step a) is in a flat state. The sheet metal material 2 has a width (transverse to the feed direction 32 and to the travel path of the second punches 18) and a length (parallel to the feed direction 32) which together span a flat surface 26 with a material thickness / wall thickness 12 (in the direction of the travel path of the second punches 18).

[0069] The device 29 is designed to carry out at least part of the described method and to produce the described sheet metal material 2. The device 29 comprises a device 31 for forming the sheet metal material 2 in the second region 11, i.e., for reducing the material thickness 12 and increasing the yield strength R p0.2 of the sheet metal material 2 in the second region 11. The device 29 further comprises a plurality of second dies 18 for simultaneously forming the sheet metal material 2, at least by deep drawing, in several sheet metal sections 25, and a holder 30 for positioning the sheet metal material 2 relative to the second dies 18.

[0070] Between step a), i.e., the provision of the sheet metal material 2, and step a2), in which the sheet metal material 2 is contacted with the second punches 18 and subsequently deep-drawn, at least partial forming of the sheet metal material 2 in the second area 11 is carried out in step a1). The second area 11 comprises or at least partially covers an annular first area 9 of the sheet metal material 2, which is contacted by a first punch 10 in a subsequent step b) of the process (see Figs. 8 and 9 The material thickness 12 of the sheet material 2 present in this second region 11 is reduced by the forming process according to step a1), thereby increasing at least one yield strength R p0,2 of the sheet material 2. The annular or ring-segment-shaped second region 11 is bounded by a (smallest) second inner diameter 16 and a (largest) second outer diameter 17.

[0071] Before step a2) or at least partially simultaneously with it, in step a3) a sheet metal section 25 is cut out from the sheet metal material 2. Step a1) takes place before step a3).

[0072] Before the second punches 18 act on the sheet metal material 2, the sheet metal material 2 already comprises a plurality of annular or ring-segment-shaped second areas 11 on the flat surface 26, which have a reduced material thickness 12 compared to the remaining surface 26. These deformations forming the second areas 11 can be produced, for example, by a press device, i.e., 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.

[0073] The second region 11 produced in each case is ring-shaped or ring-segment-shaped. The ring-segment-shaped second region 11 (or the plurality of ring-segment-shaped second regions 11 arranged together within an imaginary ring-shaped second region 11) encompasses an angular range 13 of at least 180 degrees along a circumferential direction 7. The individual ring-segment-shaped segments extend over equal angular ranges 13.

[0074] The second areas 11 are shaped like a ring (or segment).

[0075] The sheet metal sections 25 formed in steps a1), a2) and a3) are then supplied for further processing in steps b), c), c1) and d).

[0076] Fig. 3 shows a procedure immediately after step a) in a side view. Fig. 4 The procedure shows according to Fig. 3immediately after step a3) and during step a2), in a side view. Fig. 5 The procedure shows according to Figs. 3 and 4 immediately after steps a2) and a3), in a side view. Figs. 3 to 5 will be described together below. The explanations regarding... Figs. 1 and 2 will be referred.

[0077] In Fig. 3 Part of the device 29 is shown with a second punch 18. The device 29 is designed to perform steps a2) and a3) at least partially simultaneously, i.e., to cut out a sheet metal section 25 from the sheet metal material 2 according to step a3) and to contact the sheet metal material 2 with the second punch 18 and subsequent deep drawing according to step a2). Fig. 3 The second punch 18 is moved along the axial direction 3 towards the sheet metal material 2. Fig. 4Step a3) has already been carried out and the sheet metal section 25 now present is contacted by the second punch 18 and deep-drawn. Fig. 5 Step a2) is completed and the second stamp 18 is moved back to its starting position.

[0078] As in the known manufacturing process for a container 1, a (circular or contoured) sheet metal section 25 is first cut from a flat continuous sheet metal material 2 and (immediately) then formed. This forming process includes deep drawing, whereby a second punch 18 forms the sheet metal material 2 or the sheet metal section 25 into a cup-shaped container 1. This forming into the cup-shaped container 1 is carried out in step a2) before step b).

[0079] Fig. 6 The procedure shows according to Figs. 3 to 5 , where on the left is step a1), and in the middle is the state immediately after steps a2) and a3) (see also Fig. 5) and on the right, the transformation from the state immediately after step a2) to step c1) is shown; each in a side view. See the explanations regarding the Figs. 1 to 5 will be referred.

[0080] According to step a), the sheet metal material 2 is provided (see left image of the Fig. 6 ). According to step b), the sheet metal material 2 is contacted in an annular first area 9 with a first punch 10 (see right image of the Fig. 6 ) and according to step c) a subsequent deep drawing and / or extrusion of the sheet material 2 to form the bottom area 5 and the wall area 8 (see Figs. 8 and 9 Between steps a) and b), in step a1) at least a partial forming of the sheet metal material 2 takes place in a second area 11 (see left image of the Fig. 6), wherein the second region 11 at least partially encompasses the first region 9. A material thickness 12 of the sheet material 2 present in this second region 11 is reduced by the forming process, thereby increasing at least one yield strength R p0,2 of the sheet material 2.

[0081] The middle image of the Fig. 6 Figure 1 shows that a circular sheet metal section 25 is cut out of the flat sheet metal material 2 and immediately afterwards formed. This forming process includes deep drawing, in which a second punch 18 forms the sheet metal material 2, or the sheet metal section 25, into a cup-shaped container 1. This forming into the cup-shaped container 1 is carried out in step a2) before step b).

[0082] After step a2), the cup-shaped container 1 is fed to a further forming station, where it is further formed by deep drawing and / or stretching slide drawing (step c). In step b), a first punch 10, movable along the axial direction 3, strikes the bottom area 5 of the cup-shaped container 1 and, in step c), draws the sheet metal material 2 through a die (see Figs. 8 and 9 ). In this process, the bottom region 5 and the wall region 8 of the container 1 are at least partially formed. As a result of the first punch 10 impacting the bottom region 5 of the cup-shaped container 1, the sheet metal material 2 in the first region 9, where the first punch 10 makes initial contact with the sheet metal material 2 (if no pre-deformation according to step a1) has taken place), is locally damaged and the material thickness 12 is locally reduced.

[0083] In further forming processes, especially of the bottom area 5, this damage can be shifted further inwards, e.g. in a radial direction 21 (see arrow in the right image of the Fig. 6 This damaged area may be subject to further forming, potentially leading to further damage or even failure of the sheet metal material 2. In particular, the locally reduced material thickness 12 will be further reduced during the subsequent forming process, resulting in, or potentially resulting in, a material thickness 12 that is insufficient for the intended use of the container 1.

[0084] Pretreatment of the first area 9 can reduce or prevent damage resulting from contact with the first punch 10 and may at least reduce or completely suppress further damage resulting from further forming.

[0085] This is achieved in step a1) by at least partially forming the sheet metal material 2 in a second area 11, wherein the second area 11 at least partially or (as shown here) completely encompasses or covers the first area 9. The material thickness 12 of the sheet metal material 2 present in this second area 11 is reduced by the forming process, thereby increasing at least one yield strength R p0,2 of the sheet metal material 2.

[0086] This increase in the yield strength and / or the work hardening of the sheet metal material 2 achieved through forming results in the impact of the first punch 10 causing only a smaller deformation of the first area 9. Furthermore, the work hardening prevents the sheet metal material 2 present in this second area 11 from being further deformed, or only to a lesser extent, during subsequent forming operations. In particular, when forming adjacent areas, the flow of sheet metal material 2 from this second area 11 is greatly reduced or even completely eliminated, occurring only from other areas. This prevents (or largely reduces) any further reduction in the material thickness 12 in this second area 11.

[0087] The first area 9 is annular in shape and corresponds to the contact surface or impact surface of the first punch 10 on the sheet metal material 2. The second area 11 is arranged coaxially to the first area 9.

[0088] The annular first region 9 is bounded by a (smallest) first inner diameter 14 and a (largest) first outer diameter 15. The annular or ring-segment-shaped second region 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.

[0089] Each inner diameter 14, 16 runs parallel to the outer diameter 15, 17 of the same area 9, 11 and is arranged coaxially with it. 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.

[0090] Between steps a) and b), in step a2), the sheet metal material 2 is contacted with a second punch 18 and subsequently deep-drawn. The second punch 18 has a larger outer diameter 19 than the first punch 10.

[0091] Fig. 7 shows the workpiece, the cup-shaped container 1, according to Fig. 5 and a diagram. Regarding the explanations concerning the Figs. 1 to 6 will be referred.

[0092] This transformation into the cup-shaped container 1 is carried out before step b) in step a2) with the second punch 18.

[0093] The horizontal axis of the diagram shows the distance 33 of points on the surface of container 1 along the surface from the central axis 40 of container 1. The vertical axis shows the material thickness 12 of container 1 in millimeters.

[0094] It can be seen that the material thickness 12 in the base area 5 remains relatively constant at 242 µm. In the area of ​​the outer diameter 19 of the second punch 18, the material thickness reaches a minimum of approximately 235 µm. The portion of the sheet metal section 25 extending along the axial direction 3 exhibits a material thickness 12 that increases along the axial direction 3, reaching approximately 300 µm.

[0095] Fig. 8 The procedure during steps b) and c) is shown in a side view in section. Fig. 9 The procedure at the end of step c) is shown in a side view in section. Figs. 8 and 9 will be described together below. The explanations regarding the Figs. 1 to 7 will be referred.

[0096] The cup-shaped container 1, which is present according to steps a1), a2) and a3), is arranged in a device 29. This device 29 comprises a hold-down 41, a support 42 and a first punch 10. According to step b), the cup-shaped container 1 is contacted in an annular first area 9 with the first punch 10 (see also the right-hand image of the Fig. 6) and according to step c), a subsequent deep drawing and / or extrusion of the cup-shaped container 1 to form the bottom region 5 and the wall region 8. In step b), a first punch 10, movable along the axial direction 3, strikes the bottom region 5 of the cup-shaped container 1 and successively draws the sheet metal material 2 through a die or an opening in the support 42 in step c). In doing so, the bottom 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 bottom region 5 of the cup-shaped container 1, the material thickness 12 of the sheet metal material 2 is locally reduced in the first region 9, where the first punch 10 first makes contact with the sheet metal material 2. As a result of carrying out step a1), i.e. the reshaping of the second area 11, the reduction of the material thickness 12 as a result of the impact of the first punch 10 is now less.

[0097] Starting from the position of the first stamp 10 according to Fig. 9 can, during or following step c), in a step c1), a further shaping of the bottom area 5 by a third punch 20 (see Fig. 11 ) which may be arranged in a fixed position, e.g. by a further movement of the first punch 10 along the axial direction 3.

[0098] A third area 22 of the sheet material 2, arranged opposite a radial direction 21 within the hollow cylindrical first punch 10, is formed by the third punch 20 along the axial direction 3 towards the second end 6 (see Fig. 11 ).

[0099] 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 bottom region 5, so that a concave shape is formed in the bottom region 5 when viewed from the outside (see Fig. 11 ).

[0100] After step c) and after step c1), in a further step d) a further forming of the bottom area 5 takes place, wherein a wall section 23 of the third area 22 extending at least along the axial direction 3 is formed outwards in a fourth area 24 in the radial direction 21 (see Fig. 12 ).

[0101] The following Figs. 10 to 12 illustrate the problems of the current state of the art. Based on the Figs. 10 to 12 The advantages now achieved will also be explained.

[0102] Fig. 10shows the workpiece immediately before step c1) of the procedure in a side view in section and a diagram (see also shape of the bottom area 5 of the container 1 in Fig. 9 ). Regarding the explanations concerning the Figs. 1 to 9 will be referred.

[0103] On the left side of the Fig. 10 The course of the wall of container 1 is shown from the central axis 40. Measuring points are arranged at a distribution along the wall.

[0104] The horizontal axis of the diagram shows the measurement points and the distance 33. The distance 33 represents the distance of a point on the surface of container 1 from the central axis 40 along the surface of container 1. The vertical axis shows the material thickness 12 of the sheet metal 2 of container 1. The diagram shows three profiles 34, 35, 36 of the material thickness 12 of the sheet metal 2 over distances 33, or over the measurement points.

[0105] The first curve 34 connects the maxima of the material thicknesses 12 measured on a plurality of containers 1. The second curve 35 connects the mean values ​​of the material thicknesses 12 measured on a plurality of containers 1. The third curve 36 connects the minima of the material thicknesses 12 measured on a plurality of containers 1. It can be seen that curves 34, 35, and 36 each have a minimum located in the area of ​​measuring points "10" to "12". These measuring points "10" and "12" lie in the annular first area 9, which corresponds to the contact area or impact area of ​​the first punch 10 on the sheet metal 2 during step b). Material thickness 12 values ​​of up to 222 µm are reached.

[0106] These low values ​​of the material thickness 12 can be increased by pretreating the sheet material 2 according to step a1) of the process. A second area 11 thus created then extends over the first area 9 shown here.

[0107] Fig. 11 The workpiece is shown in a side view in section immediately after step c1) of the procedure, and a diagram is shown (see also the right image of the Fig. 6 ). Regarding the explanations concerning the Figs. 1 to 10 will be referred.

[0108] On the left side of the Fig. 11 The course of the wall of container 1 is shown from the central axis 40. Measuring points are arranged at a distribution along the wall.

[0109] The horizontal axis of the diagram shows the measurement points and the distance 33. The distance 33 represents the distance of a point on the surface of container 1 from the central axis 40 along the surface of container 1. The vertical axis shows the material thickness 12 of the sheet metal 2 of container 1. The diagram shows three profiles 34, 35, 36 of the material thickness 12 of the sheet metal 2 over distances 33, or over the measurement points.

[0110] The first curve 34 connects the maxima of the material thicknesses 12 measured on a plurality of containers 1. The second curve 35 connects the mean values ​​of the material thicknesses 12 measured on a plurality of containers 1. The third curve 36 connects the minima of the material thicknesses 12 measured on a plurality of containers 1. It can be seen that curves 34, 35, and 36 each have a minimum located in the range of measurement points "10" to "12".

[0111] A third region 22 of the sheet material 2, arranged within the hollow cylindrical first punch 10 with respect to a radial direction 21, is formed by the third punch 20 along the axial direction 3 towards 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 at the end of step c1). The third punch 20 has a convex contact surface with respect to the bottom region 5, so that a concave shape is formed in the bottom region 5 when viewed from the outside.

[0112] As a result of this, starting from the shape of container 1 according to Fig. 10, further forming of the bottom area 5 according to step c1) the first area 9 (and, if pretreated, the second area 11) is shifted inwards in the radial direction 21, so that after further forming the first area 9 (or the second area 11; or the measuring points 10, 12 of the Fig. 10 ) is arranged along the radial direction 21 between the first punch 9 and the third punch 20.

[0113] Due to the convex shape of the third punch 20, the first area 9 (or the second area 11) is arranged in a wall section 23 of the third area 22, which extends essentially along the axial direction 3.

[0114] The forming of the bottom area 5 according to step c1) leads to a further increase in the surface area of ​​the sheet material 2 in the bottom area 5. This further reduces the material thickness 12 in the bottom area 5 (see curves 34, 35, 36 of the diagrams in Figs. 10 and 11 ).

[0115] The displacement of the first area 9 into the further formed bottom area 5 and the resulting further reduction of the material thickness 12 due to the further forming leads to material thickness values ​​of up to 218 µm being achieved (i.e. without pretreatment according to step a1)).

[0116] In further forming processes of the bottom area 5, this damage to the first area 9 can be displaced further inwards in a radial direction 21. This damaged area 9 can then be subjected to further forming, here according to step c1), which can lead to further damage or even material failure. In particular, the locally reduced material thickness 12 is further reduced during the subsequent forming process, resulting in a material thickness 12 that is insufficient for the intended use of the container 1.

[0117] The second area 11 resulting from a pretreatment according to step a1) and extending over the first area 9 (namely the area of ​​measuring points "10" to "12") will be arranged, as described above, between the first punch 10 and the third punch 20.

[0118] Pretreatment of the first area 9 as part of step a1) can reduce or prevent damage resulting from contact with the first punch 10, and thus at least reduce or completely suppress further damage resulting from further forming.

[0119] Fig. 12 The workpiece is shown in a side view in section after step d) of the procedure. See the explanations regarding the Figs. 10 and 11 will be referred.

[0120] After step c) and after step c1), in a further step d) the bottom region 5 is further formed, wherein a wall section 23 of the third region 22, extending at least along the axial direction 3, is formed outwards in the radial direction 21 in a fourth region 24. This additional forming is carried out in particular to increase the dimensional stability of the bottom region 5, especially against the high overpressures of a beverage container.

[0121] This fourth area 24 encompasses the first area 9 and can therefore lead to material failure of the pre-damaged sheet metal material 2, which has been further reduced in material thickness 12.

[0122] The pretreatment of the first area 9 in step a1) can lead to the fourth area 24 now encompassing the pretreated second area 11, so that further damage as a result of further deformation can at least be reduced or completely suppressed.

[0123] This increase in the yield strength and / or the work hardening of the sheet metal material 2 achieved through the forming process of step a1) results in the impact of the first punch 10 causing only a smaller deformation of the first area 9. Furthermore, the work hardening prevents the sheet metal material 2 present in this second area 11 from being further deformed, or at least prevents it from being further deformed, during subsequent forming operations. In particular, when forming adjacent areas, the sheet metal material 2 does not flow from this second area 11, but rather from other areas. This prevents any further reduction in the material thickness 12 in this second area 11. Reference symbol list

[0124] 1 Container 2 Sheet metal 3 Axial direction 4 First end 5 Bottom area 6 Second end 7 Circumferential direction 8 Wall area 9 First area 10 First punch 11 Second area 12 Material thickness / Wall thickness 13 Angle area 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 Area 27 Width 28 Length 29 Device 30 Holder 31 Setup 32 Feed direction 33 Distance 34 First path 35 Second path 36 Third path 37 Lid area 38 Core angle 39 Volume 40 Center axis 41 Hold-down 42nd edition

Claims

1. Method for producing a metallic container (1) from a sheet metal material (2), the container (1), which is produced at least by deep drawing and / or stretch-glide drawing carried out 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) towards a second end (6) and is formed circumferentially in a circumferential direction (7); at least comprising the following steps: a) providing the sheet material (2); b) contacting the sheet material (2) in the base region (5) in an annular first area (9) with a first punch (10) and c) subsequent deep drawing and / or stretch-glide drawing of the sheet material (2) to form the base region (5) and the wall region (8) at least by the first punch (10); characterized in that 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) by a device (31), wherein the second area (11) at least partially comprises the first area (9), wherein 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 Rp0,2 of the sheet material (2) is increased; wherein this pretreatment of the first area (9), that is the at least partial forming of the sheet material (2) in the second area (11), results in reducing or preventing a damage that occurs as a result of the contacting of the first punch (10) and at least reducing further damage that occurs as a result of further forming.

2. Method of claim 1, wherein the second area (11) is annular or annular-segment-shaped; wherein the formed annular-segment-shaped second area (11) comprises an angular range (13) of at least 180 angular degrees along the circumferential direction (7).

3. Method according to any one of the preceding claims, wherein the annular first area (9) is bounded by a first inner diameter (14) and a first outer diameter (15); wherein the second area (11) is bounded by a second inner diameter (16) and a second outer diameter (17); wherein the second inner diameter (16) is smaller than the first inner diameter (14).

4. Method of claim 3, wherein the second outer diameter (17) is larger than the first outer diameter (15).

5. Method according to one of the preceding claims, wherein between steps a) and b) in a step a2) contacting of the sheet material (2) with a second punch (18) and subsequent deep drawing takes place; wherein the second punch (18) has a larger punch outer diameter (19) than the first punch (10); wherein the sheet material provided in step a) is in a flat state and, between steps a) and b), and before or at least partially simultaneously with step a2), a sheet section (25) is cut out of the sheet material (2) in a step a3); wherein the second punch (18) forms the sheet section (25) into a cup-like container (1), the base region (5) of which is contacted by the first punch (10) in subsequent step b).

6. Method according to claim 5, wherein step a2) occurs after step a1).

7. Method according to any one of the preceding claims, wherein the material thickness (12) in the second area (11) is reduced by at least 3 % as a result of the forming of the second area (11) and the yield strength Rp0,2 is increased by at least 5 %.

8. Method according to any one of the preceding claims, wherein step c) is carried out at least partly with the first punch (10); wherein during or subsequent to step c) in a step c1) a further forming of the base region (5) is carried out by a third punch (20), wherein a third area (22) of the sheet material (2) arranged within the first punch (10) with regard to a radial direction (21) is formed by the third punch (20) along the axial direction (3) towards the second end (6).

9. Method according to claim 8, wherein, as a result of the further forming of the base region (5) according to step c1), the second portion (11) is displaced inwardly in the radial direction (21) so that, after the further forming, the second area (11) is arranged along the radial direction (21) between the first punch (10) and the third punch (20).

10. Method according to any one of the preceding claims 8 and 9, wherein after step c) and after step c1) in a further step d) a further forming of the base region (5) takes place, wherein a wall section (23) of the third area (22), extending at least along the axial direction (3), is formed outwardly in the radial direction (21) in a fourth area (24).

11. Method of claim 10, wherein the fourth area (24) at least partially comprises the second area (11).

12. Method according to one of the preceding claims 1-4 or 6-11, wherein the sheet material (2) provided in step a) is present in a flat state and between steps a) and b) in a step a3) a sheet section (25) is cut out of the sheet material (2) so that in step c) the sheet section (25) is deep-drawn and / or stretch-glide-drawn; wherein step a1) takes place before or after step a3).

13. Apparatus (29) for producing a metallic container (1) from a sheet material (2), wherein the container (1), at a first end (4), has 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) towards a second end (6) and is formed circumferentially in a circumferential direction (7); wherein the apparatus (29) being suitably designed for carrying out the method according to one of the preceding claims; wherein the apparatus (29) comprises at least a first punch (10) for forming the sheet material (2) and for producing the base region (5) and the wall region (8) at least by deep drawing and / or stretch-glide drawing, a holder (30) for positioning the sheet material (2) relative to the first punch (10), and a device (31) for forming the sheet material (2) in the second area (11), that is for reducing the material thickness (12) in the second area (11).