METHOD AND DEVICE FOR MANUFACTURING A PRISMATIC BATTERY CELL CONTAINER

Description

[0001] The invention relates to a method and an arrangement for manufacturing a prismatic battery cell container open at one end. The battery cell container can, for example, have a cuboid shape. The battery cell container serves to hold core material, such as a winding, which provides the electrical energy. After filling the container with the core material, the battery cell container, open at one end, is closed with a lid.

[0002] Battery cell containers come in various forms. They can be made of metallic or plastic materials. The demand for batteries is steadily increasing. On the one hand, many sectors are seeing a trend towards battery-powered electrical devices and vehicles. On the other hand, batteries are also needed for storing electrical energy, particularly in the context of electricity supply using renewable energy sources such as wind or solar power.

[0003] Due to the large number of battery cells or battery cell containers required, processes are necessary to manufacture such containers economically with sufficient dimensional accuracy. This presents several challenges.

[0004] When manufacturing battery cell housings from a metal or metallic alloy, well-known processes such as deep drawing or extrusion can be used. Deep drawing is a sheet metal forming process. A sheet of metal is required as the starting material. The degree of deformation, in terms of the ratio of the battery cell housing's height to its width, is limited.

[0005] The extrusion process for battery cell containers requires a high material input. The shape of a battery cell container manufactured in this way is limited to specific geometries and dimensions to achieve the necessary material flow.

[0006] DE 698 22 448 T2 proposes a method for manufacturing a battery cell container in which an iron-based metallic sheet with a nickel layer on one side is drawn into a cup or pot. Subsequently, a battery cell container is formed by stretch drawing. Such a method first requires the production of a suitable cup or pot for the drawing process.

[0007] Such a process is called a DI process. The "D" stands for the English word "drawing" and the "I" for the English word "ironing," referring to deep drawing and stretch drawing. DI processes are also known, for example, from the production of beverage cans.

[0008] Similar manufacturing processes that begin with a deep-drawing step are also known from DE 694 17 001 T2 and DE 698 37 291 T2.

[0009] DE 1 001 095 A describes a method for producing cylindrical metallic hollow bodies. A slug is first pressed into a circular disc with a circumferential rim, which is then formed into a cylindrical body open at one end by forward extrusion.

[0010] From GB 748719 A, a method for manufacturing a battery with a plastic battery cell housing is known. The plastic housing is open on one side and may have a support projection for a lid adjacent to the open side. The lid can engage in a circumferential groove on the battery cell housing by means of a force-fit connection.

[0011] KR 10 162 1253 B1 describes a method for manufacturing a prismatic battery cell container. For this purpose, a flow-formed container is first produced by extrusion, which is then transformed into the battery cell container by stretch forming. Such a method is also known from EP 1 347 519 A1.

[0012] Based on this, it is an object of the present invention to provide an improved manufacturing process for a metallic battery cell container that ensures economical production with sufficiently good dimensional accuracy.

[0013] The problem is solved by a method according to the features of claim 1 and an arrangement with the features of claim 15.

[0014] According to the invention, a slug is first provided. It is integrally manufactured from a single material without seams or joints. The slug consists of at least one metal and / or at least one metallic alloy. Preferably, it consists of an aluminum alloy. The slug has, for example, a prismatic and, for example, a cuboid shape.

[0015] The billet is formed into a formed container by extrusion and, for example, reverse extrusion. This is a bulk forming process. The billet can be obtained simply and cost-effectively, for example, by cutting a rod-shaped or sheet-like material to length. The rod-shaped or sheet-like material can be extruded to achieve a predetermined rectangular or non-rectangular cross-sectional shape. Alternatively, the billet can be cut from a sheet of metal, for example, by punching or cutting.

[0016] The extruded container is then transported to a first stretching station. This station comprises a first stretching ram and a first die tool. The first stretching ram can be moved in a working direction towards or into the die tool. Once it reaches a reversal point within the area of ​​the first die tool, it can be moved back into a retracted position in the opposite direction. During its movement in the working direction, the first stretching ram, in conjunction with the first die tool, transforms the extruded container into a stretched container through a first stretching slide.In this process, the extruded container is not moved completely through the first die tool in the working direction by the first stretching plunger, but only to a reversal point and then moved back out of the die tool together with the first stretching plunger in a retraction direction.

[0017] After the first stretching operation, the stretched container is transported to a second stretching station and subjected to a second stretching operation using a second stretching ram and a second die. Similar to the first stretching operation, in the second stretching station the stretched container is only partially moved through the second die by the second stretching ram in the working direction and then, together with the second stretching ram, moved back out of the second die in the retraction direction. At the end of the second stretching station, the stretched container has been formed into an intermediate container. The intermediate container is dimensionally accurate in a longitudinal and a lateral direction, but not in a vertical direction, which is oriented parallel to the working and retraction directions.

[0018] In a final step, the upper edge of the intermediate container is cut off, thereby ensuring dimensional accuracy in the vertical direction and obtaining the battery cell container.

[0019] In the two stretching stations, the respective container is not moved completely through the die tool. By retracting the container in the retraction direction using the respective stretching plunger, it is possible to transport the container, formed in the stretching stations, on the same plane on which it was transported into the respective stretching station. This simplifies the manufacturing process and the corresponding manufacturing equipment. The stripping of the container from the respective stretching plunger thus occurs, viewed in the working direction, spatially in front of the respective die tool and temporally after the forming process, during the retraction movement of the respective stretching plunger.

[0020] This method can also be used to manufacture prismatic battery cell containers that have very different dimensions in a lateral direction and in a longitudinal direction oriented perpendicular to it. For example, the dimension in the longitudinal direction can be at least 4 to 5 times larger, and preferably at least 7 times larger, than in the lateral direction. This applies to prismatic battery cell containers with a rectangular or polygonal cross-section or base.

[0021] It is advantageous if the extruded container has a polygonal bottom whose dimension in one direction is at least 4 to 7 times larger than in another direction, with the two directions being perpendicular to each other and spanning a plane that extends parallel to the bottom. The die and the press ram in an extrusion station are dimensioned accordingly.

[0022] It is advantageous if the bottom of the extruded container has four corner areas, two longitudinal sides, and two transverse sides. The longitudinal side can be at least 4 to 5 times, and preferably at least 7 times, longer than the transverse side.

[0023] The extruded container can have at least one pair of longitudinal side walls that are opposite each other and curve away from each other. Each longitudinal side wall can be curved or arched about at least one axis of curvature, which preferably extends parallel to the vertical direction.

[0024] The upper edges of the longitudinal and / or transverse sides of the extruded container may have a curved profile and be lower in the corner areas than in a central section between the corner areas. The maximum height of a side wall, and in particular a longitudinal side wall, may be 5% to 20%, and preferably 7% to 17%, greater in the central section than the minimum height in either of the two corner areas.

[0025] In one embodiment, the distance between the longitudinal side walls of the extruded container is at least 5% to 10% greater in the middle between the corner areas than the distance at the corner areas. Similarly, in the extrusion mold, the distance between the two longitudinally extending inner walls is at least 5% to 10% greater in the middle between the corner areas than at the corner areas of the mold.

[0026] In a preferred embodiment, the base of the extruded container has a thickness corresponding to a predetermined target thickness for the battery cell container. Therefore, no further forming of the base is required after extrusion. The thickness of the base is preferably less than the wall thickness of the side walls, i.e., the longitudinal and transverse side walls, of the extruded container.

[0027] A target value for the wall thickness of the side walls of the extruded container can be in the range of 0.5 mm to 1.5 mm, and preferably from 0.7 mm to 1.1 mm, including the respective range limits. This allows the wall thickness of the side walls to be reduced substantially to the target thickness in a single drawing operation using a single die tool. This minimizes the number of subsequent machining steps. To enable extruded wall thickness drawing, it is advantageous if the wall thickness of the side walls of the extruded container deviates from the specified target value of the finished battery cell container by a maximum of 0.3 mm, and particularly by a maximum of 0.1 mm.

[0028] It is also preferred if the extruded container is coated with a drawing oil or other lubricant before the first drawing operation. The lubricant is applied at least to the outside of the extruded container's side walls, since the forming work takes place there in contact with the die during the drawing operation. The lubricant selectively influences the friction.

[0029] In an advantageous embodiment of the method, during the first stretching slide and / or the second stretching slide, a support step with a predetermined height distance to the bottom is formed in the side walls of the stretched container or the intermediate container. The support step serves as a bearing surface for a lid, by means of which the battery cell container, open on one side, can be closed after the core material, for example a winding, has been filled in.

[0030] Preferably, the first and / or second drawing plunger has a projection for forming the support step, which is arranged at a predetermined vertical distance from the respective end face of the drawing plunger. The projection is particularly present around the entire circumference of the drawing plunger and projects in a plane perpendicular to both the working and retraction directions. It is also advantageous if the wall thickness of the side walls of the extruded container is reduced by approximately 5% to approximately 30%, and preferably by approximately 10% to 20%, during the first drawing operation. This allows the target thickness of the side walls to be achieved almost immediately during the first drawing operation.

[0031] It is particularly preferred if the wall thickness of the side walls of the drawn container is reduced by less than 1% during the second drawing operation. The inner diameter of the die tool in the second drawing station can be equal to or smaller than the inner diameter of the die tool in the first drawing station. Due to the elasticity of the material, the drawn container expands slightly again after being drawn out of the first die tool. It then acquires its final shape through the second drawing operation in the second drawing station.

[0032] The wall thickness of the side walls of the manufactured battery cell container deviates from a predetermined target value of the finished battery cell container by a maximum of 0.1 mm, preferably by a maximum of 0.05 mm, and more preferably by a maximum of 0.01 mm, due to the method described above.

[0033] Advantageous embodiments of the invention are described in the dependent claims, the description, and the drawings. Preferred embodiments of the invention are explained in detail below with reference to the drawings. The drawings show: Figure 1a a butt according to the state of the art, Figures 1b and 1c each a schematic perspective representation of an exemplary embodiment of a lump, Figure 2 a schematic representation of a press station for extrusion in a longitudinal section, Figure 3 the extrusion station Figure 2 in a top view of the press mold according to section line III-III in Figure 2 , Figures 4a and 4b Each a schematic side view of an extruded container, Figure 5 a schematic top view of the extruded container in Figure 4a according to arrow V, Figures 6-10Each a schematic representation of a first stretching station at different stages during a first stretching sliding pull of the extruded container, Figure 11 a schematic representation of the transfer of the container straightened in the first straightening station to a second straightening station, Figure 12 a schematic representation of a second stretching station, Figure 13 a schematic representation of a separation station for separating an upper edge of the intermediate container delivered from the second stretching station, Figure 14 a cross-sectional view through the manufactured prismatic, one-sided open battery cell container, Figure 15 a schematic perspective representation of the manufactured battery cell container, Figure 16 a schematic, block diagram-like representation of a device for manufacturing the battery cell container and Figure 17A schematic partial representation of a preferred embodiment of a drawing ring.

[0034] In Figure 16 The figure shows a highly schematic embodiment of a device 20 designed for the production of a prismatic, and for example cuboid-shaped, battery cell container 21 that is open on one side. In this embodiment, the device 20 comprises a flow forming station 22 with a press ram 23 and a die 24, a first drawing station 25 with a first drawing plunger 26 and a first die 27, a second drawing station 28 with a second drawing plunger 29 and a second die 30, and a cutting station 31 with a cutting device 32. Details of the device 20 are described in the following sections. Figures 1-15 and the explanation of the procedure.

[0035] The production of the battery cell container 21 is carried out step by step, first by extrusion of a slug 38 in the extrusion press station 22. A slug 38 known from the prior art has ( Figure 1a ) a cuboid shape. The length of the slug 38 is greater than its width by a factor of at least 4-5 or at least 7. The shape of the slug 38 is approximately adapted to the press die 24 into which the slug 38 is placed for extrusion.

[0036] In the Figures 1b and 1cAccording to the invention, different contours of the slug 38 are illustrated. In the region of the short side (width of the slug), more material is required for subsequent extrusion to form the slug 38 into an extruded container than in a central region of the longer sides of the slug 38. Therefore, the slug 38 has a larger cross-sectional area in the two longitudinal end regions adjacent to the short sides than in a central region between the two longitudinal end regions.

[0037] To achieve this, in one example, the thickness of the nub can vary and increase towards the shorter sides, starting from a central area ( Figure 1b Alternatively or additionally, the width of the butt 38 can vary and be smallest in a central area along its length, increasing from there to the two short sides, as shown schematically in Figure 1cThis embodiment, viewed from above or from below, has a shape similar to an hourglass or a bone. The two narrow, longitudinally extending sides are, for example, concavely curved inwards towards each other, so that the shank 38 has a waisted shape.

[0038] According to the invention, the solid forming of the billet 38 to produce the extruded container 41 is carried out by a so-called reverse extrusion process. First, the billet is placed in the die 24. Then, the punch 23 is inserted into the die 24, leaving a circumferential gap 40 between the punch 23 and the inner walls 39 of the die 24. The material flows into this gap 40 when the punch 23 presses the billet 38 against the bottom of the die 24, thereby forming the billet 38. This produces an extruded container 41. Figures 4 and 5 ).

[0039] The extruded container 41 has a base 42 and four side walls 43, 44, which adjoin each side of the base 42, thus forming an integrally formed extruded container 41 open on one side. The extruded container 41 has two lateral side walls 43 extending in a lateral direction B and two longitudinal side walls 44 extending in a longitudinal direction L. The longitudinal direction L and the lateral direction B are perpendicular to each other and define a plane parallel to the base 42. A dimension of the extruded container 41 in the longitudinal direction L corresponds to a length x, and a dimension in the lateral direction B of the extruded container 41 corresponds to a width y.

[0040] The width y is not constant, for example. At the four corner regions 45, the extruded container 41 has a minimum width ymin, and in the longitudinal direction L between two adjacent corner regions 45 connected by one of the longitudinal side walls 44, the extruded container 41 has a maximum width ymax. The maximum width ymax is preferably present in the center of the extruded container 41 in the longitudinal direction L. The varying width y results from an outwardly curved shape of the longitudinal side walls 44, the distance of which increases from the corner regions 45 to the center of the extruded container 41 in the longitudinal direction L and decreases from there towards the corner regions 45. Viewed from the outside, a longitudinal side wall 44 of the extruded container 41 has a convex curvature along its extent in the longitudinal direction L.A difference dy between the maximum width ymax and the minimum width ymin is thus achieved by the longitudinal side surfaces 44 curving away from each other. The maximum width ymax is preferably at least 5% to 10% larger than the minimum width ymin.

[0041] The upper edges of the side walls 43, 44 of the extruded container 41 can have a curved profile ( Figures 4a, 4b The height z of the side walls 43, 44 of the extruded container 41 is therefore not constant, but varies. A maximum height zmax can, for example, be reached in a central area of ​​a side wall 34, 44, and a minimum height zmin can be found in one of the two corner areas 45 adjacent to the respective side wall 43, 44. The maximum height can be 5% to 20% or, in particular, 7% to 17% greater than the minimum height zmin, resulting in a difference dz in the height z ( Figure 4b). This height difference applies at least to the longer of the side walls, i.e., here the longitudinal side walls 44.

[0042] The thickness sb of the base 42 of the extruded container 41 essentially corresponds to the target thickness of the base of the battery cell container 21. In the subsequent forming steps of the extruded container 41, the thickness sb of the base is not substantially altered. The thickness sb of the base 42 is less than the wall thickness sw of the side walls 43, 44 of the extruded container 41. The wall thickness sw of the side walls 43, 44 can be approximately in the range of 0.5 mm to 1.5 mm and preferably from 0.7 mm to 1.1 mm, including the respective limits of this range. The deviation from the target value of the wall thickness sw is preferably at most 0.3 mm and more preferably at most 0.1 mm. This simplifies the subsequent stretching sliding pull of the extruded container 41 and the positioning of the extruded container 41 on the first stretching plunger 26.

[0043] The extruded container 41 is transported from the extrusion station 22 to the first stretching station 25, preferably along a transport plane T. In the first stretching station 25, the extruded container 41 is positioned aligned with the first stretching plunger 26. The extruded container 41 can be positioned on a counter support 51 below the first stretching plunger 26. The first stretching plunger 26 can be moved from a retraction position in a working direction A onto the first die tool 27 until it reaches a reversal position U ( Figure 9 Starting from this reversal position U, the first extension plunger 26 can be moved back into the retraction position in a retraction direction R that is opposite to the working direction A. During its movement in the working direction A or in the retraction direction R, the first extension plunger 26 performs a linear movement along its longitudinal axis.

[0044] The first stretching plunger 26 has a rectangular cross-section that corresponds to the internal shape of the battery cell container 21 to be manufactured. The first stretching plunger 26 has an end face 50 that is oriented perpendicular to the working direction A. After the first stretching plunger 26 begins to move in the working direction A from its retraction position (not shown), the first stretching plunger 26 engages in the extruded container 41 until its end face 50 is in contact with the bottom 42 of the extruded container 41. Figure 6The extruded container 41 is supported by a counter-support 51. The counter-support 51 has a support surface 52 on which the underside of the base 42 of the extruded container 41 rests. The counter-support 51 is pre-tensioned in the retraction direction R, and thus opposite to the working direction A, by means of a pre-tensioning device 53 with a pre-tensioning force F. The pre-tensioning device 53 can be, for example, a spring device and, in particular, a gas spring device. The counter-support 51 can be moved in the working direction A by the movement of the first drawing plunger 26 against the pre-tensioning force F. The pre-tensioning force F is sufficiently large to support the engagement of the first drawing plunger 26 in the extruded container 41 and to clamp the base 42 between the end face 50 and the support surface 52 during forming, so that during forming or...During the stretching and sliding drawing of the extruded container 41, unwanted deformation of the bottom 42 is avoided. During the first stretching and sliding drawing in the first stretching station 25, the support surface 52 is always in contact with the bottom 42.

[0045] The first die tool 27 is formed by one or more drawing rings 54. In the exemplary embodiment, two working steps or forming steps are effected by means of the first die tool 27 in conjunction with the first drawing plunger 26. The two forming steps can be effected by two separate drawing rings 54 or by a common drawing ring 54 with a first ring section 55 and a second ring section 56. In the preferred embodiment shown here, the drawing ring 54 is divided in the working direction A into a first ring section 55 and an immediately adjoining second ring section 56. The drawing ring 54 is integrally made of a single material. Two separate drawing rings or two separate ring sections 55, 56 made of different materials could also be used.

[0046] The first ring section 55 has an inner diameter that is larger than the inner diameter of the second ring section 56. When the extruded container 41 is moved into the first drawing ring 54 or the first ring section 55 by the movement of the first drawing plunger 26 in working direction A, an initial forming of the side walls 43, 44 occurs, thereby fixing the extruded container 41 to the first drawing plunger 26. The degree of forming achieved by the first ring section 55 is small and, in particular, smaller than the degree of forming by the subsequent second ring section 66. This fixing step is shown schematically in Figure 7 shown.

[0047] By a continued movement in the working direction A of the first stretching plunger 26, the extruded container 41 is moved through the second ring section 56, whereby the actual forming of the side walls 43, 44 takes place ( Figure 8The wall thickness sw of the side walls 43, 44 decreases, while the height of the side walls 43, 44 increases in a vertical direction H that is perpendicular to the longitudinal direction L and the lateral direction B. The vertical direction H is parallel to the working direction A and the retraction direction R, respectively.

[0048] The cross-section of the first drawing plunger 26 is, for example, not constant. At a distance from the end face 50, the first drawing plunger 26 has a circumferential projection 60. The projection 60 forms, so to speak, an annularly closed step with a projection surface 61, which, in this embodiment, extends in a plane that is oriented perpendicular to the working direction A. The projection surface 61 has a normal vector that, for example, runs parallel to the working direction A. In the retracted position of the first drawing plunger 26, the projection surface 61 faces the first die tool 27.

[0049] In a variation of the preferred embodiment, the projection surface 61 can also be oriented at an angle other than 90 degrees to the working direction A.

[0050] The projection 60 increases the cross-sectional area in the direction of the end face 50 of the first drawing plunger 26. The distance between the projection 60 and the end face 50 corresponds to, or defines, a vertical distance z.

[0051] If the height of the side walls 43, 44 is increased by further shaping, the material flows along the first drawing plunger 26 over the projection 60. The material flow over the projection 60 is shown schematically in Figure 9This can be seen. There, the first stretching plunger 26 has reached its reversal position U and reverses its direction of movement from a movement in the working direction A to an opposite movement in the retraction direction R. It can be seen that the container was not completely moved through the first die tool 27.

[0052] Due to the material flow over the projection 60, a support step 62 is formed on the side walls (compare Figure 11 and 13-15 The support step 62 provides a support surface 63 for a lid, which can be inserted into the battery cell container 21 adjacent to the opening of the battery cell container 21 and placed onto the support surface 63. The battery cell container 21 is closed with the help of such a lid after the core material has been inserted.

[0053] The orientation of the support surface 63 corresponds to the orientation of the projection surface 61. For example, the support surface 63 is aligned perpendicular to the vertical direction H of the battery cell container 21.

[0054] In the first stretching station 25, stretched containers 65 are obtained from the extruded container 41 by the first stretching sliding drawing process. A stripping device 71 is provided which strips the stretched container 65 from the first stretching plunger 26 during the movement of the first stretching plunger 26 in the retraction direction R. Figure 10The stripping device 71 can, for example, be formed by a stripping ring arranged coaxially to the first stretching plunger 26. Viewed in the retraction direction R, the first stripping device 71 is located at a distance from the first die tool 27 or the transport plane T. After stripping, the stripped, stretched container 65 is located on the support surface 52 of the counter holder 51, which is then positioned approximately in the transport plane T. This corresponds to the initial position of the counter holder 51.

[0055] The extended container 65 is shown schematically in the Figures 10 and 11 illustrated. It has a bottom 66 which essentially corresponds to the bottom 42 of the extruded container 41. The stretched container 65 has four side walls, namely two longitudinal side walls 67 and two transverse side walls 68, of which in cross-section in the Figures 10 and 11Only one is discernible. The side walls 67, 68 have an edge section 70 following the opening 69 opposite the base 66, which was not, or not completely, moved by the first die tool 27. The edge section 70 completely encloses the opening 69 circumferentially and forms an end of the side walls 67, 68 that has a greater wall thickness, approximately corresponding to the wall thickness sw of the extruded container 41. In contrast, the wall thickness of the side walls 67, 68 of the stretched container 65 is about 20% to 30% less than the wall thickness sw of the extruded container 41.Due to the increase in cross-section of the first stretching plunger 26 following the projection 60, the wall thickness of the stretched container 65 is further reduced in the vertical direction H towards the opening 69 between the support step 62 and the edge section 70, whereby the wall thickness here is therefore reduced by more than 20% to 30% compared to the wall thickness sw of the extruded container.

[0056] By means of a transfer device 75, which is only illustrated in a highly schematic way, the stretched container 65 is moved along the transport level T into the second stretching station 28 ( Figure 11 ). Such a transfer device 75 can also be used for transport from the extrusion station 22 to the first drawing station 25.

[0057] The drawn container 65 already essentially has the wall thicknesses, the base thickness, and the dimensions in the width direction B and in the length direction L that correspond to the battery cell container 21 to be manufactured. Therefore, only a minor deformation takes place in the second drawing station 28 through the second drawing slide drawing of the drawn container 65. The wall thickness of the side walls 67, 68 is reduced by a maximum of 1% in the second drawing station 28 during the second drawing slide drawing.

[0058] The second drawing station 28 is essentially identical in construction to the first drawing station 25, so reference can be made to the preceding description. The only difference is that the second die tool 30 is formed by a second drawing ring 76, the dimensions or contours of which may differ from those of the first drawing ring 54. The second drawing ring 76 is, for example, divided into a first ring section 55 and a second ring section 56, analogous to the first drawing ring 54. The difference in the inner diameter of the first ring section 55 from the second ring section 56 is smaller in the second drawing ring 76 than in the first drawing ring 54. The inner diameter of the second ring section 56 of the second drawing ring 76 may correspond to the inner diameter of the second ring section 56 of the first drawing ring 54.Even if these inner diameters are the same size, forming work is performed in the second stretching station 28 during the second stretching slide drawing, since elastic springback of the material of the stretched container 65 after the first stretching slide drawing results in an increase in the outer dimensions of the stretched container 65, which is at least partially reversed during the second stretching slide drawing in the second stretching station 28.

[0059] The degree of deformation in the second stretching station 28 is low. Preferably, the wall thicknesses of the side walls 67, 68 of the stretched container 65 are reduced by a maximum of 1%. The second stretching slide drawing operation serves for calibration. The contours, particularly in the corner areas of the stretched container 65, are adjusted, and any remaining excessively large radii of curvature in the corner areas are reduced.

[0060] The process of the second stretching slide drawing in the second stretching station 28 corresponds to that of the first stretching slide drawing in the first stretching station 25, so reference is made to the preceding description. It is explicitly pointed out here that, in the exemplary embodiment, even during the second stretching slide drawing, the stretched container 65 is not moved completely in the working direction A through the second die tool 30, but is moved back in the retraction direction R at a corresponding reversal point, contrary to the working direction A, as was also described in connection with the first stretching slide drawing. After the second stretching slide drawing, the stretched container 65 is formed into an intermediate container 77.The intermediate container 77 is stripped off by the second stretching plunger 29 in the second stretching station 28 by means of a stretching device and is then located on the support surface 52 of the counter-holder 51, with the underside of the bottom being located approximately in the transport plane T. The intermediate container 77 is in . Figure 13 Illustrated. Since the intermediate container 77 in the exemplary embodiment essentially corresponds to the elongated container 65, reference is made to the preceding description of the elongated container 65 for a description of its shape. The intermediate container 77 thus has a bottom 78 from which two longitudinal side walls 79 and two transverse side walls 80 extend to an opening 81. The support step 62 with the support surface 63 and the edge section 70 are still present in the intermediate container 77.

[0061] Figure 17Figure 1 illustrates a section of the first drawing ring 54 or the second drawing ring 76 with a preferred embodiment of an inner surface that comes into contact with the extruded container 41 or the drawn container 65, respectively, during the drawing-slide forming process. On its upper side opposite the second ring section 56, the first ring section 55 has a conical insertion surface 55a that widens away from the second ring section 56. The angle of inclination α relative to the working direction A can be 2 to 5 degrees, and for example, 3 degrees. A lateral surface 55b of the first ring section 55 adjoins the insertion surface 55a and is oriented parallel to the working direction A. In particular, the area bounded by the lateral surface 55b serves to fix the container 41 or 65 to be formed.

[0062] The second ring section 56 adjoins the cylindrical surface 55b. The surface section of the second ring section 56 adjoining the cylindrical surface 55b has an approximately S-shaped cross-sectional contour with a first radius R1 and a second radius R2. In a top view of the inner surface of the drawing ring 54, 76, the first radius R1 forms a concave surface section and the second radius R2 a convex surface section. The two radii R1 and R2 have a common tangent at the transition point between the concave and convex surface sections, so that the transition from the first radius R1 to the second radius R2, or from the concave to the convex surface section, is smooth and seamless.

[0063] The transition from the first radius R1 or from the concave surface section to the lateral surface 55b of the first ring section 55 is preferably tangential and thus stepless and edgeless.

[0064] The first radius R1 is preferably smaller than the second radius R2. The first radius R1 is preferably smaller than the second radius R2 by a factor of 2-6. In the exemplary embodiment, the first radius is smaller than the second radius R2 by a factor of 4.

[0065] At the transition from the base 42 to a corresponding side wall 43, 44, the container 41 or 65 to be formed has a third radius R3. The third radius R3 is preferably smaller than the second radius R2 and / or larger than the first radius R1. In the exemplary embodiment, the third radius R3 can be larger than the first radius R1 by a factor of 1.2 to 1.6 and, for example, by a factor of 1.4.

[0066] The second radius R2, or the convex surface section, transitions tangentially, and thus seamlessly and without edges, into a lateral surface 56a of the second ring section 56, which is aligned parallel to the working direction A. Each part of the lateral surface 56a of the second ring section 56 is aligned parallel to a preceding part of the lateral surface 55b of the first ring section 55 in the working direction A.

[0067] In the present embodiment, rectangular containers 41, 65 are formed, and the lateral surfaces 55b, 56a each form a substantially rectangular ring that is closed around the working direction A. As described, the two lateral surfaces 55b, 56a are connected to each other seamlessly and without edges by the concave surface section with the first radius R1 and the tangentially adjoining convex surface section with the second radius R2.

[0068] The dimensions of the intermediate container 77 in the width direction B and in the length direction L correspond, both internally and externally, to the battery cell container 21 to be manufactured. To ensure dimensional accuracy in the height direction H, the intermediate container 77 is transported, for example, from the second stretching station 28 along the transport level T to the cutting station 31. There, the edge 82 adjoining the opening 81 of the intermediate container 77 is cut off using the cutting device 32. A cutting line 83, along which the edge 82 is cut off, is shown in Figure 13 The dividing line 83 is shown schematically with dashed lines. It lies between the edge section 70 and the support step 62 or the support surface 63. The edge 82 can be recycled.

[0069] The battery cell container 21 obtained after separating the edge 82 is in the Figure 14 and 15The figure illustrates this. It has a base 90 opposite an opening 91 of the battery cell container 21. The opening 91 is bounded by four side walls: two opposing longitudinal side walls 92 and two opposing transverse side walls 93. The side walls 92 and 93 are integrally connected to the base 90 and to the respective adjacent side walls 93 and 92, respectively, without any seams or joints. In the vertical direction H, at a distance from the opening 91, the support surface 63 of the support step 62 is located and faces the opening 91. A lid can be placed there to close the battery cell container 21.

[0070] The battery cell container 21 has a cuboid shape. The two longitudinal side walls 92 and the two transverse side walls 93 are each aligned parallel to each other. The battery cell container 21 has an external dimension al in the longitudinal direction L, which is at least 4 to 5 times larger, and for example at least 7 times larger, than an external dimension ab in the transverse direction B. The external dimension al of the battery cell container 21 is at most 15 times larger than the external dimension ab in the transverse direction B. An external dimension ah of the battery cell container 21 in the vertical direction H can be larger, equal to, or smaller than the external dimension ab in the transverse direction B. For example, the external dimension ah in the vertical direction H is significantly smaller than the external dimension al in the longitudinal direction L.

[0071] In the exemplary process, the extruded container 41 is provided with a lubricant before the first drawing operation and / or before the second drawing operation, at least on the outer surfaces of the side walls 43, 44, in order to optimize the friction between the containers and the relevant die tool 27, 30. A drawing oil, for example, can be used as the lubricant.

[0072] The invention relates to a method and a device 20 for manufacturing a prismatic, one-sided open battery cell container 21. First, a slug 38 is extruded into a container 41. The slug 38 is made of a uniform material. The extruded container 41 is then reshaped by a first stretching slide in a first stretching station 25 and by a second stretching slide in a second stretching station 28. During the stretching slide, the container is only partially moved through an associated die tool 27, 30 by a respective stretching plunger 26, 29 and moved back upon reaching a reversal point U. After the second stretching slide, a remaining rim 82 of the resulting intermediate container 77 is cut off, thus obtaining the battery cell container 21. Reference symbol list:

[0073] 20 Device 21 Battery cell container 22 Extrusion press station 23 Press punch 24 Press die 25 First stretching station 26 First stretching plunger 27 First die tool 28 Second stretching station 29 Second stretching plunger 30 Second die tool 31 Separation station 32 Separation device 38 slug 39 inner wall of the press mold 40 gap 41 extruded container 42 bottom of the extruded container 43 wide side wall of the extruded container 44 long side wall of the extruded container 45 corner area of ​​the extruded container 50 End face of the first drawing plunger 51 Counterhold 52 Support surface 53 Preload device 54 First drawing ring 55 First ring section 55a Insertion surface 55b Sleeve surface of the first ring section 56 Second ring section 56a Sleeve surface of the second ring section 60 Projection 61 Projection surface 62 Support step 63 Support surface 65 Extended container 66 Bottom of the extended container 67 Longitudinal side wall of the extended container 68 Broad side wall of the extended container 69 Opening of the extended container 70 Edge section 71 Scraper device 75 Transfer device 76 Second stretching ring 77 Intermediate container 78 Bottom of the intermediate container 79 Longitudinal side wall of the intermediate container 80 Broad side wall of the intermediate container 81 Opening of the intermediate container 82 Edge of the intermediate container 83 Separation line 90 Bottom of the battery cell container 91 Opening of the battery cell container 92 of the battery cell container 93 of the battery cell container α Inclination angle A Working direction ab External dimension in the width direction of the battery cell container ah External dimension in the height direction of the battery cell container al External dimension in the length direction of the battery cell container B Width direction dy Difference between maximum and minimum width dz Difference between maximum and minimum height F Preload force H Height direction L Length direction R Withdrawal direction R1 First radius R2 Second radius R3 Third radius sb Thickness of the bottom of the extruded container sw Thickness of the side wall of the extruded container T Transport plane U Reversal position x Length of the extruded container y Width of the extruded container ymax Maximum width of the extruded container ymin Minimum width of the extruded container z Height of the side walls of the extruded container zmax Maximum height of the side walls of the extruded container zmin Minimum height of the side walls of the extruded container

Claims

1. Method for manufacturing a unilaterally open prismatic battery cell container (21) with the following steps: - providing a slug (38), which has a length between its two length end regions that is about a factor of minimum 4-5 greater than a width of the slug (38) and which comprises a larger cross-section area in the two adjacent length end regions adjacent to the short sides than in a mid region between the two length end regions, - manufacturing a unilaterally open extruded container (41) by extrusion of the slug (38), - first ironing of the extruded container (41) into an ironed container (65) in a first ironing station (25), wherein the extruded container (41) is partly moved through a first die tool (27) in working direction (A) and out of the first die tool (27) opposite the working direction (A) in a retracting direction (R) by a first ironing ram (26), - second ironing of the ironed container (65) in an intermediate container (77) in a second ironing station (28), wherein the ironed container (65) is partly moved through a second die tool (30) in working direction (A) and out of the second die tool (30) opposite the working direction (A) in a retracting direction (R) by a second ironing ram (29), - separating an upper edge (82) of the intermediate container (77) for forming the battery cell container (21).

2. Method according to claim 1, characterized in that the extruded container (41) comprises a polygonal bottom (42), the dimension thereof in a direction (L) is at least about the factor 4- to 7-times larger than in another direction (B), wherein the two directions (L, B) are orientated rectangular to each other.

3. Method according to claim 2, characterized in that the bottom (42) of the extruded container (41) comprises four corner regions (45), two length sides and two width sides.

4. Method according to claim 3, characterized in that the extruded container (41) comprises adjacent to each length side of the bottom (42) one length side wall (44) that oppose each other and that camber away from each other.

5. Method according to claim 4, characterized in that the distance between the length side walls (44) in the middle between the corner regions (45) is at least 5% to 10% greater than the distance in the corner regions (45).

6. Method according to any of the preceding claims, characterized in that the thickness (sb) of the bottom (42) of the extruded container (41) is smaller than the wall thickness (sw) of the side walls (43, 44) of the extruded container (41).

7. Method according to any of the preceding claims, characterized in that a target value for the wall thickness (sw) of the side walls (43, 44) of the extruded container (41) is between 0.5 mm and 1.5 mm or between 0.7 mm and 1.1 mm.

8. Method according to any of the preceding claims, characterized in that the wall thickness (sw) of the side walls (43, 44) of the extruded container (41) deviates at most by 0.3 mm or at most by 0.1 mm from a predetermined target value.

9. Method according to any of the preceding claims, characterized in that lubricant is supplied on the extruded container (41) before the first ironing.

10. Method according to any of the preceding claims, characterized in that during the first ironing and / or during the second ironing a rest step (62) with a predefined height distance (z) from the bottom (66, 78) is formed in the side walls of the ironed container (65) and / or the intermediate container (77).

11. Method according to claim 10, characterized in that the first ironing ram (26) and / or the second ironing ram (29) comprise a protrusion (60) for forming the rest step (62) that is arranged with the height distance (z) away from the end face (50) of the respective ironing ram (26, 29).

12. Method according to any of the preceding claims, characterized in that the wall thickness (sw) of the side walls of the extruded container (41) is reduced between 5% and 30% during the first ironing.

13. Method according to claim 12, characterized in that the wall thickness (sw) of the side walls of the extruded container (41) is reduced between 10% and 20% during the first ironing.

14. Method according to any of the preceding claims, characterized in that the wall thickness (sw) of the side walls (67, 68) of the ironed container (65) is reduced by less than 1% during the second ironing.

15. Arrangement comprising a slug (38) and a device (20) for manufacturing a unilaterally open prismatic battery cell container (21), wherein the slug (38) comprises a length between its two length end regions that is about a factor of minimum 4-5 greater than a width of the slug (38) and which comprises a larger cross-section area in the two adjacent length end regions adjacent to the short sides than in a mid region between the two length end regions, wherein the device is configured to carry out the method according to any of the preceding claims and comprises: - an extrusion press station (22) comprising a press ram (23) and a unilaterally open press mold (24), - a first ironing station (25), comprising a first ironing ram (26) moveably in a working direction (A) and opposite the working direction (A) in a retracting direction (R) and a first die tool (27), - a second ironing station (28), comprising a second ironing ram (29) moveable in working direction (A) and in retracting direction (R) and a second die tool (30), and - a separating station (31), comprising a separating device (32) for separating an edge (82) from an intermediate container (77).