Tool device for producing a bipolar plate and method

Abstract

Tool device (100) with a press (110) having at least two, preferably three or four, pressing devices (111, 112, 113, 114), designed to produce a bipolar plate (40) from a sheet metal (42) with a thickness (44) of less than 0.25 mm, in particular 0.1 mm, by means of embossing, having an embossing tool set (10) having a first tool (W1), wherein the first tool (W1) is designed to emboss a bead (S) into the sheet metal (42) in a first embossing production step in the tool device (100), wherein the embossed bead (S) has a closed, partially curved contour (K) in the plane of the sheet metal (42), and with the first tool (W1) provided in the first pressing device (111) for embossing the bead (S) into the sheet metal (42) and with at least one further, in particular second, third and / or fourth, tool (W2, W3, W4) for embossing the sheet (42), wherein the at least one further tool (W2, W3,W4) is designed for advance contact with the bead (S) embossed into the sheet (42) by the first tool (W1) and is provided in a further, in particular second, third and / or fourth, pressing device (112, 113, 114) of the tool device (100).

Description

[0001] The present invention relates to a tooling device with a press for producing a bipolar plate. Furthermore, the invention relates to a method for producing a bipolar plate from a sheet metal by means of stamping in a tooling device.

[0002] In particular, the invention relates to the series production of bipolar plates. Thus, the respective tooling device is preferably designed for the production of a plurality of bipolar plates from a plurality of sheets in series production.

[0003] DE 10 2019 103 606 A1 describes a forming tool and a forming method for producing a predetermined overpressure break point in a battery cover. The forming tool comprises a punch tool, a die tool, and optionally a blank holder assembly. The punch tool has a punch part whose cross-section corresponds to a bead to be produced in the battery cover.

[0004] DE 20 2020 103 228 U1 discloses a bipolar plate with improved temperature distribution, which has a self-contained perimeter bead for sealing the active area.

[0005] US 2004 / 0 151 975 A1 describes a bipolar fuel cell separator plate of variable length and a manufacturing method in which a tool is used to introduce groove structures into the center region of a sheet metal strip. After the structure is introduced into a portion of the sheet metal strip, the strip is separated from a coil.

[0006] When manufacturing a bipolar plate using a tooling device such as a press, the sheet metal is typically unwound from a roll with a sheet metal strip (in particular so-called coils), formed or embossed in the press - whereby channel structures are introduced into the sheet metal - and then separated or punched out piece by piece, for example, to create bipolar plates. The sheet metal is usually made of high-strength stainless steel. Since the sheets also usually have a thickness of less than 1 mm, for example a thickness of approx. 0.1 mm, it is particularly challenging to ensure that the bipolar plate has an approximately constant thickness despite high stroke rates or high production speeds, is free of cracks and residual stresses and has sufficient flatness and accuracy of the length and width dimensions or outer contours.

[0007] The object of the invention is therefore to provide a solution with which the dimensional accuracy in the series production of bipolar plates and the production speed or the number of strokes can be increased.

[0008] The object is achieved by a tool device having the features of claim 1 and by a method having the features of claim 8. Preferred embodiments of the invention are specified in the subclaims and the description, which may each individually or in combination represent an aspect of the invention.

[0009] In particular, the tool device is designed to produce a plurality of the bipolar plates from a plurality of the sheets in a series production.

[0010] A stamping tool set for producing a bipolar plate from a sheet metal with a thickness of less than 0.25 mm, in particular 0.1 mm, by stamping is used, comprising a first tool for a pressing device of a press or the tool device, wherein the first tool is designed to stamp a bead into the sheet metal in a stamping first production step of the tool device, wherein the stamped bead has a closed, partially curved contour in the plane of the sheet metal. The stamping tool set should be suitable for quantities in the range of 1,000, 10,000, 100,000, or more, and should therefore preferably have good wear resistance.

[0011] Where "singular" is used in the disclosure of the application, i.e., the singular of a feature, particularly for the sheet metal or bipolar plate, the "plural" of the respective feature is also intended to address series production. In series production, sheets or bipolar plates are typically produced in cycles, undergo an identical process, and are identical in form and shape. Therefore, it is linguistically and technically simpler to refer to a singular object or feature, even though, given the nature of series production, this will result in a multitude of objects or features.

[0012] A tooling device is understood to be the entirety of the components involved in production. The press of the tooling device essentially contains all components that effect the forming of the sheet metal, particularly during a stroke of the press, e.g. simultaneously, including one or more pressing devices and the stamping tool set with one or more tools. A single pressing device focuses on one stamping step and typically uses one tool from the stamping tool set. In addition to the press, the tooling device can also contain, for example, a gripping device, a feed device and / or a cutting device. One or more of these devices can also be operatively connected to a stroke of the press or a pressing device.

[0013] As already mentioned, the tool device is preferably suitable for series production. The tool device can therefore have a holder for a or the sheet metal strip, in particular a coil, from which unwinding or uncoiling is possible, for example by means of an unwinding device and / or by means of the feed device. The unwinding device can, for example, drive an unwinding axis in the middle of the wound sheet metal strip. However, the feed device can also unwind the sheet metal strip from the holder, for example by pulling it. The sheet metal strip can thus be advanced to the cutting device. In particular, the sheet metal strip can be held by an or the at least substantially horizontal unwinding axis of the holder in order to be able to advance the sheet metal as flatly and without twisting to the typically horizontally arranged and / or cutting cutting device.

[0014] The press is particularly suitable for stamping or processing very thin sheet metal, especially with a thickness of less than 1 mm or less than 0.25 mm, for example 0.1 mm. This involves processing stainless steel sheets, for example. Press forces of over 1000 or 2000 kN are usually used here. The tools must be designed to be wear-resistant accordingly. Each press device, for example, carries out one of several stages or steps of production, in particular whereby the sheet metal must be transported from press device to press device in the direction of production. The direction of production will usually be straight.

[0015] Embossing is the process of forming a material, for example, by placing an upper punch onto a corresponding lower punch with the sheet metal positioned between them, so that the sheet metal is plastically deformed and adapts to the punches. The embossing tool set typically comprises two corresponding punches between which the sheet metal is placed. The embossing tool set is particularly suitable for stainless steel sheets. The embossing tool set itself or individual components thereof can therefore also be made of stainless steel; in particular, a harder material than that of the sheet metal should be used.

[0016] The first tool is specifically designed to emboss the bead, but the first tool can also perform other forming and / or separating production steps, such as punching holes. The bead has a closed and partially curved contour in the plane of the sheet metal. This means that in a plan view of the bead, a particularly predominant surface section of the sheet metal can be described as being framed by the bead. The bead is usually curved in the corner areas of the sheet metal, near a centering contour, near a bipolar plate contour, near a cut of a cutting device and / or near holes. In particular, the bead runs at least substantially along the edge of the sheet metal. In a plan view of the bead, the cross-sectional shape of the bead is essentially not recognizable because it is typically edgeless.Rather, the shape of the bead is visible in the cross-section. Typically, the bead has a U-shape in cross-section. Compared to the original state of the sheet, the bead exhibits no, or at least no significant, thinning of the sheet. Rather, the bead has a concave part on one side and a convex part on the other.

[0017] The advantage of the proposed solution is that it allows the production of a bipolar plate that is already stabilized at the beginning and / or before the sheet is stamped. The bead stiffens the bipolar plate or sheet during and after production. The bead enables stretch forming during the stamping of the channel structures, which significantly reduces residual stresses in the sheet or bipolar plate and increases the thickness continuity of the stamped sheet. Springback is avoided when tools are opened from the just-stamped sheet. Flatness deviations are reduced. The channel structures can be manufactured without cracks. Scrap is reduced. Especially in the context of series production of a large number of bipolar plates, the bead can enable high stroke rates and high handling speeds to be achieved because the sheet is less unstable and does not vibrate as much during rapid movements.

[0018] It is preferably provided that the first tool has an upper punch and a lower punch corresponding to the upper punch for embossing the sheet metal, wherein the punches for embossing the bead into the sheet metal have an upper and lower bead geometry, respectively. The bead geometry corresponds, for example, at least substantially to a negative of the bead to be embossed. In this way, the upper and lower bead geometries can be inserted into one another. However, the sheet metal with the bead can also be arranged between the upper punch with the upper bead geometry and the lower punch with the lower bead geometry, wherein in both cases a positive connection is created. In a plan view, the respective bead geometry can have the closed, partially curved contour of the bead. However, the upper and lower bead geometries do not have to be closed, but can be applied to different sections on the first tool oron the upper punch or the lower punch. The bead can thus be produced quickly and in a single stamping step with the first tool. The first tool can also perform further forming and / or separating operations on the sheet metal.

[0019] It can further preferably be provided that the upper bead geometry has a groove and / or that the lower bead geometry has a projection. In this respect, it is preferred if a concave bead geometry is provided on the upper punch and / or if a convex bead geometry is provided on the lower punch. It has been found that the sheet metal with the bead can be best fixed via the bead if the bead can be accessed from below and not from above. This is because the bead can be better centered on a projection than if it can be centered in a groove with its own projection.

[0020] If a second, a third and / or a fourth tool is provided, each with an upper punch and a lower punch, designed to emboss the sheet metal in a second, third or fourth production step at least in an area framed by the bead or the contour, then the bead in the sheet metal can be advantageously used and the flatness deviations of the bipolar plate to be produced can be further reduced. In this respect, it is preferred if the bipolar plate is first produced by producing a bead and then by further forming steps. The embossing tool set is to be designed accordingly in that the first tool concentrates on the bead and that the second or another tool concentrates on forming the channel structures and, for example, engages in the bead to fix the sheet metal.

[0021] It can be provided that the upper and / or lower punch of the second, third and / or fourth tool is / are designed for advance contact with the bead in a stamping direction. This has the particularly advantageous effect that when the second or another tool is closed, the sheet metal is fixed first. This is because the advance contact can be achieved by a movable part, in particular a part movable in the stamping direction, first touching the sheet metal and clamping the sheet metal against the bead, in particular clamping the sheet metal over the entire contour of the bead. This mobility then ensures that the actual geometry of the tool can also come into contact with the sheet metal for stamping or forming.

[0022] A particularly preferred embodiment is characterized by a spring-loaded upper holding part which leads in one or the stamping direction and has at least substantially the upper bead geometry and / or a spring-loaded lower holding part which leads in one or the stamping direction and / or has at least substantially the lower bead geometry. In particular, the respective holding part can be moved in the stamping direction by one or more millimeters relative to the base body of the respective upper or lower punch. Within the scope of the mobility, a preload is simultaneously provided on the holding part, which can be in the order of magnitude of the actual pressing force, for example 100, 250, 500, 2000 or 7000 kN or values in between. This can be achieved with sufficiently rigid springs, e.g. coil springs or gas springs, within the respective punch.Another advantage is that the retaining parts can be easily replaced, especially in the event of wear or geometry changes. This reduces costs.

[0023] A tool device with a press is proposed. The press has at least two pressing devices; three, four or more pressing devices can also be provided. The tool device is designed to produce a bipolar plate from a sheet metal having a thickness of less than 0.25 mm, in particular 0.1 mm, by means of embossing. In particular, the tool device is designed to produce a plurality of bipolar plates from a plurality of sheets in series production. The tool device furthermore has the above-described embossing tool set, with a embossing tool in the at least one or more embossing tools.a first tool provided in the first pressing device for stamping a bead into the sheet metal and at least one further tool for stamping the sheet metal, wherein the at least one further tool is designed for advance contact with the bead stamped into the sheet metal by the first tool and is provided in the further, in particular second, third and / or fourth, pressing device of the tool device. The tool device according to the invention enables highly precise and rapid production of bipolar plates. In particular, this is due to the fact that with the help of the bead, a flatness deviation of the sheet metal is reduced. Although an additional production step is introduced, the stroke rates can be increased and productivity can be improved.

[0024] The first pressing device can be provided for embossing the bead, and preferably for punching, into the sheet metal, in particular by means of the first tool. The second pressing device can be provided for pre-embossing the sheet metal, wherein the sheet metal can be held in the region of the bead by leading holding parts when the press is closing in order to enable stretching; in particular, the second tool can be used here. The third pressing device can be provided for finish-embossing or calibrating, wherein the sheet metal can be held in the region of the bead by leading holding parts when the press is closing in order to enable stretching; in particular, the third tool can be used here. The fourth or final pressing device can also be provided for calibrating and / or piercing or punching, wherein the sheet metal can be held in the region of the bead by leading holding parts when the press is closing in order to minimize distortion.However, the fourth or final pressing device can also be designed without any leading retaining parts, e.g., in the area of the bead, to perform the calibration, punching, or piercing, since stretching is no longer required here. In particular, the fourth or final pressing device uses the fourth tool.

[0025] If the tooling device includes a cutting device for cutting the sheet metal from a sheet metal strip, smaller material sections can be used to manufacture bipolar plates, and handling is facilitated in conjunction with the bead. Furthermore, material utilization can be increased.

[0026] The cutting device ensures, for example, that the sheet metal is separated from the sheet metal strip, preferably cut out or removed, for example by means of a lifting movement of a cutting blade. If the cutting device is located upstream of the press, in particular at least one, several or all pressing devices, the unprocessed sheet metal typically passes through the cutting device before the first stamping in order to be cut or removed from the sheet metal strip. The cutting device can be used to cut the sheet metal strip before stamping, in particular before stamping the bead. If a feed device is provided, it is advantageously attached in the immediate vicinity of or to the cutting device. The attachment can be achieved, for example, by screwing, clipping, inserting one into the other, or with a material-to-material connection. This avoids a gap across which the sheet metal strip or sheet can sag.The feed device can then move or advance the sheet metal strip or sheet from the feed device directly, i.e. without production-related intermediate stations such as embossing, to the cutting device.

[0027] The cutting device can be arranged directly upstream of the first tool or the first pressing device or the press as a whole to enable a compact design. If a feed device for advancing a sheet metal strip or the sheet metal strip is provided in front of the first tool, the unwound materials can be precisely maintained to ensure the length of the bipolar plate is maintained. In particular, the feed device can be arranged directly upstream of the cutting device to achieve high precision. The feed device can advance transversely to a production direction predetermined by the arrangement of the tools or the at least two pressing devices in order to have the original winding of the sheet metal strip also oriented transversely to the production direction.Experience has shown that this is beneficial for manufacturing accuracy if the sheets are also gripped at opposite ends transverse to the production direction, because this allows the original winding to be smoothed out by pre-tensioning. The feed device can also advance in the direction of the cutting device, i.e., feed it directly or indirectly. In particular, the feed device can advance in a feed direction, transverse or perpendicular to the production direction.

[0028] A gripping device for gripping the sheet metal and for transporting the gripped sheet metal in the production direction can be provided on the pressing device(s) and / or the cutting device. The sheet metal can be gripped, in particular, at opposite perforations. For example, the sheet metal can be gripped at a position in the region of the cutting device, e.g. after cutting, transported to the first pressing device in particular and then released so that the pressing device can carry out the embossing. In particular, the gripping device can transport or handle the sheet metal starting from or to the (preferably first, second or further etc.) pressing device and / or cutting device. The gripping device can transport between pressing devices and / or the cutting device, for example transport a cut-off sheet metal to the first pressing device.The advantage here is that separate systems for handling the sheet metal—the feed device and the gripping device—can operate and be designed independently of each other. This also allows for a simple change of direction from the direction of the sheet metal strip to the direction of production, creating a compact device and utilizing improved material orientation. Especially in conjunction with the beading, the sheet metal can be transported quickly because it is no longer as unstable.

[0029] The method according to the invention for producing a bipolar plate from a sheet metal with a thickness of less than 0.25 mm, in particular 0.1 mm, by means of embossing in the tool device described above comprises the following steps or measures. In particular, the method is provided or designed for the production of a plurality of bipolar plates from a plurality of sheets in series production. The sequence of the steps is exemplary. Further steps can be added, or steps can be modified, or even omitted.

[0030] Step a): Providing the sheet metal. For example, a sheet metal strip or a so-called coil containing the sheet metal or the plurality of sheets can be provided, in particular unwound. A feed device or the cutting device can be used here. A cutting device or the cutting device can also be used here. Typically, providing the sheet metal is one of the first steps or the first step of the process. In series production, providing a single sheet metal strip or coil is sufficient to manufacture the plurality of bipolar plates. Once the sheet metal strip has been used up or processed into bipolar plates, another sheet metal strip can be provided.

[0031] Step b): Embossing a bead, in particular with a contour that is closed in the plane of the sheet and curved in sections, into the sheet by means of the first tool, which is designed to emboss the bead into the sheet. In this step, a separation of the sheet can also be carried out, in particular by means of the first tool, e.g. during the embossing of the bead, in particular at least one hole and / or an outer contour can be produced on the sheet in a separating manner. The first tool is typically used by the first pressing device in the press of the tool device to produce the bead.

[0032] Step c): Transporting the sheet metal with the embossed bead in a production direction into a second tool or into a second pressing device which is designed to emboss the sheet metal. The method can be advantageously further developed by gripping the sheet metal and transporting the gripped sheet metal in the production direction. In particular, a gripping device is used which is designed to grip into opposite holes in the sheet metal. The holes can have been created by the cutting device. In particular, the gripping device can be arranged and transported along the production direction. Preferably, the gripping and transporting are carried out after cutting and before embossing. The gripping and transporting can also be carried out after embossing.Alternatively or additionally, the gripping and transporting is carried out after a first embossing in a first pressing device and before a subsequent / second embossing in a subsequent / second pressing device; analogously, gripping and transport can take place between the second and third, or third and fourth, etc., pressing devices. Finally, the gripping and transporting can also take place from the last pressing device in the direction of production (e.g., the second, third, fourth, etc. pressing device; however, the first pressing device is also possible if only one of these is provided) to a removal option such as a conveyor belt and / or a storage area.

[0033] Step d): Closing the second tool or the second pressing device or the press, in particular in a stamping direction, wherein a holding part of a punch of the second tool first comes into contact with the bead in a stamping direction, and wherein the sheet is subsequently stamped with the second tool away from the bead. In this step, channel structures can be stamped into the sheet, in particular those that can be used for the chemical reaction in a fuel cell to be formed from the bipolar plates.

[0034] The advantage of the proposed process is that the bipolar plate is manufactured in multiple stages, thus achieving greater precision despite multiple stages and being faster to produce because the beading enables higher stroke rates and also increases accuracy through greater rigidity and the possibility of stretch forming. In series production, higher stroke rates can be achieved because the beading makes the sheet more stable and allows for faster transport to the second tool.

[0035] The process can be further developed by stamping the sheet metal using an additional pressing device of the press. The additional pressing device is arranged downstream of the first and second pressing devices, particularly in the direction of production. Stamping is preferably carried out in three, four, or more stages in cycles—depending on the number of pressing devices—to obtain highly dimensionally accurate bipolar plates.

[0036] Preferably, in step a), the sheet metal is unwound and cut from the sheet metal strip by a cutting device of the tooling device and / or advanced by a feed device, in particular transversely to the production direction. As already explained above, the feed transversely to the production direction leads to certain advantages. In particular, if the feed device is arranged in the immediate vicinity of the cutting device and / or the first tool, a highly precise bipolar plate, in particular the length, can be provided.

[0037] In particular, in series production, stamping takes place simultaneously in each tool, preferably while cutting is taking place in the cutting device. When stamping is not in progress, all sheets can be handled or transported further.

[0038] With regard to the above-described embodiments of the method and the resulting advantages, but also with regard to other possible advantageous developments of the method, reference is also made to the above-described details of the tool device.

[0039] In the context of the above and the following disclosure, the abbreviation "resp." is a short form for "respectively" and is generally intended to indicate alternative, essentially equivalent, and / or synonymous features or terms in order to convey the idea or meaning of a feature or term. "Respectively" can always be replaced with "and / or."

[0040] The invention will now be explained by way of example with reference to the accompanying drawings using preferred embodiments, wherein the features presented below may represent an aspect of the invention both individually and in combination. They show: Fig. 1A-B: a sheet cut from a sheet metal strip with a cutting device immediately after cutting (A) and the sheet immediately after a first stamping by means of a first tool in a first pressing device (B) in a plan view, Fig. 2: a tool device with a cutting device and a press having four tools and in a perspective view, Fig. 3: the tool device with a feed device attached to the cutting device in a perspective view, Fig. 4 a sheet gripping device for the tool device in a perspective view, and Fig. 5 the first tool in a cut.

[0041] In Fig. 1A shows a sheet metal 42 that has been cut from a coil or sheet metal strip 41 by a cutting device 102. The sheet metal 42 has three perforations 48 on each of two opposite bipolar plate contours 43. The bipolar plate contours 43 and the perforations 43 were created by the cutting device 102. The bipolar plate contours 43 enable the sheets 42 to be cut from the sheet metal strip 41 with approximately no waste. The length 45 is determined by the cut of the cutting device 102 as a function of the length 45 pushed through. The width 46 is predetermined by the width 46 of the sheet metal strip 41 and corresponds to the width 46 of the bipolar plate 40. The sheet metal has a thickness 44 of 0.1 mm. The sheet metal 42 has four centering contours 49 on the edge. The sheet 42 is flat and in this state - after cutting - has no elements protruding from the plane.

[0042] Fig. 1B shows the sheet 42 of the Fig. 1A, wherein the sheet metal 42 has been embossed a first time to produce a bead S and eight further perforations 48. The sheet metal 42 has the bead S with a contour K that is closed in the plane of the sheet metal 42 and curved in sections. The contour K frames the eight further perforations 48. The original six round perforations 48 are arranged outside the contour K, of which three perforations 48 are opposite the remaining three perforations 48. These perforations 48 arranged outside the bead S serve to grip the sheet metal 42, e.g., with a gripping device 210.

[0043] In Fig. 1B is the sheet, as already in Fig. 1A, shown in a top view. In this view, the bead S is convex toward the viewer or has a projection. On the rear side, the bead S has a corresponding groove. In cross-section, the bead is U-shaped. The sheet 42 is fundamentally flat and, in this state—after cutting and initial stamping—has the bead S as a protruding element.

[0044] In Fig. 2 is a tool device 100 for producing a bipolar plate 40 from a sheet 42 such as that of Fig. 1A and 1B, respectively, with a thickness 44 of 0.1 mm along a production direction X. The bipolar plate 40 can be manufactured in the tooling device 100 by stamping the sheet metal 42. The stamping can be carried out in a press 110, which has four pressing devices 111, 112, 113, 114. Furthermore, a cutting device 102 is provided for cutting the sheet metal 42 from a coil or sheet metal strip 41 (not shown).

[0045] The tool device 100 of the Fig. 2 is designed for the production of a plurality of bipolar plates 40 from a plurality of sheets 42 in series production. In each of the pressing devices 111, 112, 113, 114, pressing or stamping can take place simultaneously, thereby enabling a multi-stage, stamping production process. Raw material for producing a plurality of bipolar plates 40 from sheets 40 that are individually cut from the sheet metal strip 41 can be fed to the tooling device 100 from the coil or sheet metal strip 41 (not shown). Fig. 2, the four pressing devices 111, 112, 113, 114 each have a lower punch 30, 60 of four tools W1, W2, W3, W4 of a stamping tool set 10. The pressing devices 111, 112, 113, 114 or tools W1, W2, W3, W4 are arranged in a row in the production direction X. Along the production direction X, the cutting device 102 is followed by the first pressing device 111 with the first tool W1, this is followed by the second pressing device 112 with the second tool W2, this is followed by the third pressing device 113 with the third tool W3, and this is followed by the fourth pressing device 114 with the fourth tool W4. Between the stages or steps thus formed along the production direction X, an intermediate station 120 is arranged in each case, which serves to deposit the cut or stamped sheet 42.After the fourth pressing device 114 there follows in particular a removal possibility (not shown) such as a conveyor belt, which can convey or transport transversely or in the direction of the production direction X, or a storage device.

[0046] The first tool W1 of the Fig. 2 is designed for embossing the bead S and for embossing a total of eight holes 48 framed by the bead S in the sheet 42 (cf. the sheet 42 of the Fig. 1B).

[0047] According to the presentation of the Fig. 2, the second tool W2, which is arranged downstream of the first tool W1 in the production direction X, can emboss or pre-emboss channel structures into the sheet 42 using an upper punch 50 (not shown in detail). Here, the sheet 42 can be held over the bead. The second tool W2 also serves as a so-called pre-drawing or pre-embossing stage.

[0048] The Fig. 2 The third tool W3, located downstream of the second tool W2, can stamp in a similar manner to the second tool W2, but in particular can perform finish stamping or calibration. The second tool can already perform the calibration by stretching or drawing the (pre-)stamped sheet 42 from the second tool W2 when it is held over the bead. The geometry of the channel structures can be completely created with the third tool W2.

[0049] After all, this is Fig. 2 For example, the fourth tool W4, which is arranged downstream of the third tool E3, also has a calibration stage with which the shape of the sheet 42 produced up to this point, or essentially the shape of the bipolar plate 40, can be calibrated. In particular, the fourth tool W4 is designed for punching or perforating.

[0050] In the individual tools W1, W2, W3, W4 of the Fig. 2, centering of the sheet 42 can be achieved via centering contours 49 on the sheet 42 or on the edge of the sheet 42.

[0051] The first tool W1 has a non- Fig. 2 and a lower punch 30 corresponding to the upper punch 20 for stamping the sheet 42. The punches 20, 30 have an upper and lower bead geometry 24, 34 for stamping the bead S into the sheet 42. The upper bead geometry 24 has a groove and the lower bead geometry 34 has a projection, with reference to the following explanations to the Fig. 5 shown cross section of the first tool.

[0052] The other tools W2, W3, W4 of the Fig. 2 each have an upper punch 50 and a lower punch 60. The punches 50, 60 are designed to emboss the sheet 42 in a second, third, or fourth manufacturing step, at least in an area B framed by the bead S or the contour, but also outside of it if necessary.

[0053] The second and the third fourth tool W2, W3 of the Fig. 2 have in common that they are designed for leading contact with the bead S stamped into the sheet metal 42 by the first tool W1. In this respect, the upper punches 50 each have a spring-loaded upper holding part 52, which leads in a stamping direction Y and has essentially the upper bead geometry 24. Not shown is the spring-loaded upper holding part 52, which leads in the stamping direction Y and has at least essentially the upper bead geometry 24. Also not shown is a lower holding part 62, which leads in or the stamping direction Y and / or has at least essentially the lower bead geometry 34.

[0054] The fourth tool W4 of the Fig. 2 engages the bead S, but does not advance during embossing, calibration or punching.

[0055] The tool device 100 is in Fig. 2 is basically only shown with a lower half, while an upper half is hidden for clarity; this means that of the four pressing devices 111, 112, 113, 114 or the four tools W1, W2, W4, W4, a lower punch 30 or 50 is shown, but no upper punch 20 or 60, and that a lower part of the cutting device 102 with a flat surface 101 for supporting the sheet metal strip 41, but no cutting knife 103 and no holding mechanism 106 is shown.

[0056] In Fig. 2, the cutting device 102 is positioned upstream of the press 110 with respect to the production direction X. The cutting device 102 can thus cut the sheet 42 from the sheet metal strip 41 before it is stamped. The cutting device 102 can also create perforations 48 and / or centering contours 49 in the sheet 42.

[0057] The tool device 100 further comprises a not in Fig. 2, but in Fig. 3, which is attached to the cutting device 102 and is designed to advance the sheet metal strip 41 from the feed device 104 directly to the cutting device 102. The feed device 104 is, in particular, screwed to the cutting device 102, for example, indirectly via a machine table or directly by screwing it on. The cutting device 102 can feed directly onto the flat surface 101 of the cutting device 102. This prevents the sheet metal strip 41 from sagging, enabling precise cutting.

[0058] Fig. 3 further shows a stamp 107 of the Fig. 2, the holding mechanism 106 of the cutting device 102 is still hidden. The punch 107 is designed to correspond to the flat surface 101 and, together with the flat surface 101, can essentially clamp the sheet metal strip 41 flat in the area of the sheet metal 42 and thus flatten the sheet metal 42. With the sheet metal 42 clamped, the cutting blade 103 can cut the sheet metal 42 across its entire width 46 and, at the same time, introduce a bipolar plate contour 43 across the width 46 by means of a blade contour 105. The holding mechanism 106 is intended to cut the sheet metal strip 41 in a pre-tensioned manner.

[0059] The cutting device 102 of the Fig. 3 is designed to cut the sheet metal strip 41 to a length 45 corresponding to a length 45 of the bipolar plate 40. The cutting device 102 is designed to create three perforations 48, particularly in one cut. If necessary, the cutting device 102 can create four centering contours 49 in an edge region of the sheet metal 42.

[0060] Fig. 4 shows a gripping device 210 of a tool device 100. The gripping device 210 is also present in the tool device 100 of the Fig. 3. The gripping device 210 is provided for gripping the sheet 42 and for transporting the gripped sheet 42 in the production direction X. For this purpose, the gripping device 210, as shown in sections in Fig. 3 is evident, in Fig. 4 is shown in perspective. The gripping device 210 is arranged along the production direction X and can grip the sheet 42 after each cutting or stamping and transport it to the next intermediate station 120, the next pressing device 111, 112, 113, 114, and / or to the storage facility. The gripping device 210 is particularly useful in series production in order to be able to insert or remove a sheet 42 into each of the pressing devices 111, 112, 113, 114 with each press stroke, or to transport the sheets 42 to the next station at the appropriate rate along the production direction.

[0061] In particular, the gripping device 210 of the Fig. 3 or 4 follow the production cycle. The gripping device 210 has opposing gripping mechanisms 212, which can grip into opposite holes 48 of the sheets 42 by means of a lower engagement pin 214 on an engagement pin holder 216, each of which engages into a counterholder 224. The gripping mechanisms 212 are pneumatically controlled in the present case. The gripping mechanisms 212 can be moved along the production direction X. The sheets 42 can thus be transported in a centered and pre-tensioned manner and ultimately deposited at one or the next "station" in the tool device 100. In particular, the gripping mechanisms 212 can simultaneously transport one or more sheets 42 over half a distance between two pressing devices 111, 112, 113, 114, including gripping and releasing. After such transport, the gripping mechanisms 212 can be retracted and perform this process again.Thus, a sheet can be transported or handled in cycles from the cutting device 102 to the first intermediate station 120, then to the first pressing device 111, then to the subsequent intermediate station 120, then to the second pressing device 112, then to the subsequent intermediate station 120, then to the third pressing device 113, then to the last intermediate station, then to the fourth pressing device 114, and then to the removal facility.

[0062] The cutting device 102 of the Fig. 3 is arranged downstream of the feed device 104 and, together with the feed device 104, clamps a feed direction V transverse to the production direction X, cf. Fig. 3. The feed device 104 is designed to advance the sheet metal strip 41 or sheet 40 in the feed direction V. The feed direction V runs transversely to the production direction X, more precisely, orthogonally. The feed device 104 can unwind the sheet metal strip 41 (not shown) from a roll (not shown). The roll can therefore be placed close to the press 110. The feed device 104 is positioned upstream of both the press 110 and the cutting device 102 with respect to the production direction X.

[0063] The feed device 104 of the Fig. 3 is embodied here as a roller feed. The roller feed can engage directly via opposing rollers on an upper side and an underside of the sheet metal strip 41. The feed device 104 can pre-tension the sheet metal strip 41 or sheet 42 up to the cutting device 102, particularly when the holding mechanism 106 clamps or holds the sheet 42. This can be done by the feed device 104 briefly reversing the usual feed direction V, which points in the direction of production X. Although this does not result in any significant feed movement of the sheet metal strip 41, a tensile force is nevertheless exerted in the sheet metal strip 41. This further levels the sheet metal strip 41, allowing it to be cut more precisely.

[0064] Fig. Figure 5 shows the first tool W1 in a cross-section. The upper punch 20 and the lower punch 30 corresponding to the upper punch 20 emboss an intermediate sheet 42. The tool W1 or the first pressing device 111 is closed or is located at the so-called bottom dead center, i.e., at the lowest point during embossing. This creates the bead S and the eight perforations 48 within the bead S. The punches 20, 30 have an upper and lower bead geometry 24, 34 for embossing the bead S into the sheet 42. The upper bead geometry 24 has a groove. The lower bead geometry 34 has a projection. Two punches 108 of the first tool W1 or the upper punch 20 each create the perforations 48.

[0065] If, in particular, bipolar plates 40 are produced from sheets 42 using the tool device 100 shown and described, the production or a method can be designed or proceed as follows. A bipolar plate 40 has a thickness 44 of less than 0.25 mm, for example 0.1 mm, and is produced by embossing in the tool device 100 of the Fig. 2 manufactured.

[0066] A sheet metal strip 41 containing the sheets 42 is provided. The sheets 42 are or the sheet metal strip 41 is, for example, unwound from a roll and advanced transversely to the production direction X. A first sheet 42 is then severed or cut from the sheet metal strip 41 to a length 45 by means of the cutting device 102, wherein perforations 48, centering contours 49 and / or the bipolar plate contour 43 can also be produced on / in the (first) sheet 42. In addition, the (first) sheet 42 is embossed stepwise or incrementally by means of the pressing devices 111, 112, 113, 114. A bead S can also be embossed into the sheet 42 after cutting or in the first step. This is a great advantage because the first sheet 42 or sheets 42 are not cut off after embossing, as proposed by the state of the art, but before embossing.

[0067] The method utilizes gripping device 210, which is configured to grip into the opposing perforations 48 in the (first) sheet 42. Gripping device 210 grips the (first) sheet 42 and transports it in the production direction X, specifically from cutting device 102 to intermediate station 120 after cutting. When the (first) sheet 42 is at intermediate station 120, further cutting can already be performed on a second / subsequent sheet 42 advanced to cutting device 102. Gripping device 210 then transports first sheet 42 to first pressing device 111 and second sheet 42 to intermediate station 120, while a third / subsequent sheet 42 is advanced to cutting device 102.In this arrangement, the first pressing device 111 can emboss the first sheet 42, in particular emboss the bead S, the second sheet 42 remains at the intermediate station 120, and the third sheet 42 is in turn cut from the sheet metal strip 41. The process repeats itself, with the first sheet 42 remaining at intermediate stations 120 three more times and being embossed, calibrated, and / or punched three more times at the subsequent three pressing devices 112, 113, and 114, whereupon the first sheet 42 is transported to the storage facility. The same occurs with all subsequent sheets 42.

[0068] The second, third, and / or fourth pressing devices 112, 113, 114 can come into contact with the bead S in advance in a stamping direction Y when the press 110 is closed, for example via a particularly spring-loaded holding part 52 on the upper punch 50, whereby the sheet 42 can then be stamped in the area delimited by the bead S or away from the bead S using the same tool W2, W3, W4. It is then advantageously possible for the sheet 42 to be stretched because it is held against displacement by the bead.

[0069] In particular, the cutting and embossing occur simultaneously when the press 110 is closed. The cutting device 102, in particular the holding mechanism 106 and / or the cutting blade 103, can be operatively connected to the press 110 or fixed to the press 110.

[0070] In series production, particularly after the sheet metal strip 41 has been advanced or unrolled, a first sheet 42 can be cut off and four additional sheets 42 can be stamped simultaneously. Four additional sheets 42 can also remain at the intermediate stations 120. Thus, for example, a total of nine sheets 42 are involved in the process simultaneously. After each cycle of the press 110, a finished bipolar plate 40 can be removed from the fourth pressing device 114, and another, still uncut and unstamped sheet 42 can be conveyed to the cutting device 102 or advanced to it. List of reference symbols 10 embossing tool set 20 upper stamp 22 upper stamp part 24 upper bead geometry 30 lower stamp 32 lower stamp part 34 lower bead geometry 40 bipolar plate 41 sheet metal band 42 sheet metal 43 Bipolar plate contour 44 thickness 45 length 46 width 48 holes 49 Centering contour 50 upper stamp 52 upper holding part 60 lower stamp 62 lower holding part 100 tool fixtures 101 flat surface 102 Cutting device 103 cutting blades 104 Feed device 105 Knife contour 106 Holding mechanism 107 stamps 108 hole punches 110 Press 111 first pressing device 112 second pressing device 113 third pressing device 114 fourth pressing device 120 intermediate station 210 gripping device 212 gripping mechanism 214 engagement pin 216 engagement pin holder 224 counterholder K Contour S bead V Feed direction W1 first tool W2 second tool W3 third tool W4 fourth tool X Production direction Y embossing direction

Claims

[1] Tool device (100) with a press (110) having at least two, preferably three or four, pressing devices (111, 112, 113, 114), designed to produce a bipolar plate (40) from a sheet metal (42) with a thickness (44) below 0.25 mm, in particular 0.1 mm, by means of embossing, having an embossing tool set (10) having a first tool (W1), wherein the first tool (W1) is designed to emboss a bead (S) into the sheet metal (42) in a first embossing production step in the tool device (100), wherein the embossed bead (S) has a closed, partially curved contour (K) in the plane of the sheet metal (42), and with the first tool (W1) provided in the first pressing device (111) for embossing the bead (S) into the sheet metal (42) and with at least one further, in particular second, third and / or fourth tool (W2, W3, W4) for stamping the sheet (42), wherein the at least one further tool (W2, W3,W4) is designed for advance contact with the bead (S) embossed into the sheet (42) by the first tool (W1) and is provided in a further, in particular second, third and / or fourth, pressing device (112, 113, 114) of the tool device (100). [2] Tool device (100) according to claim 1, characterized by that the first tool (W1) has an upper punch (20) and a lower punch (30) corresponding to the upper punch (20) for embossing the sheet metal (42), wherein the punches (20, 30) have an upper and lower bead geometry (24, 34) for embossing the bead (S) into the sheet metal (42). [3] Tool device (100) according to claim 2, characterized by that the upper bead geometry (24) has a groove and / or that the lower bead geometry (34) has a projection. [4] Tool device (100) according to one of the preceding claims, characterized by, a second, a third and / or a fourth tool (W2, W3, W4), with (each) an upper punch (50) and a lower punch (60), designed to emboss the sheet (42) in a respective second, third or fourth manufacturing step at least in an area (B) framed by the bead (S) or the contour. [5] Tool device (100) according to claim 4, characterized by that the upper and / or lower punch (50, 60) of the second, third and / or fourth tool (W2, W3, W4) are / is designed in a stamping direction (Y) for advance contact with the bead (S). [6] Tool device (100) according to one of claims 2 to 5, characterized byan upper holding part (52) leading in one or the embossing direction (Y) and spring-loaded with at least substantially the upper bead geometry (24) and / or a lower holding part (62) leading in one or the embossing direction (Y) and / or spring-loaded with at least substantially the lower bead geometry (34). [7] Tool device (100) according to one of claims 1 to 6, characterized by a cutting device (102) for cutting the sheet metal (42) from a sheet metal strip (41) and / or a feed device (104) for advancing one or the sheet metal strip (41) in front of the first tool (W1), in particular for advancing in the direction of the cutting device (102) and / or transversely to a production direction (X) predetermined by the arrangement of the tools (W1, W2). [8] Method for producing a bipolar plate (40) from a sheet (42) with a thickness (44) of less than 0.25 mm, in particular 0.1 mm, by means of embossing in a tool device (100) according to one of claims 1 to 7, which tool device is designed in particular for producing a plurality of the bipolar plates (40) from a plurality of the sheets (42) in series production, comprising the steps: a) providing the sheet (42) and / or a sheet strip (41), in particular coils, with the plurality of sheets (42) and, b) embossing the bead (S) with the contour (K) closed in the plane of the sheet (42) and curved in sections, into the sheet (42) by means of the first tool (W1) which is designed to emboss the bead (S) into the sheet (42), c) transporting the sheet (42) with the embossed bead (S) in a production direction (X) into a second tool (W2) which is designed to emboss the sheet (42), in particular by means of a gripping device (210) which is designed to grip into opposite holes (48) in the sheet (42), d) closing the second tool (W2), wherein firstly a holding part (72) of a punch (70) of the second tool (W2) comes into contact with the bead (S) in a stamping direction (Y), and wherein subsequently stamping of the sheet (42) with the second tool (W2) takes place away from the bead (S), in particular wherein channel structures are stamped into the sheet (42). [9] Method according to claim 8, wherein in step a) the sheet metal (42) is unwound and cut from the sheet metal strip (41) by a cutting device (102) of the tool device (100) and / or is advanced by a feed device (104), in particular transversely to the production direction (X).

Images