Method and roller apparatus for producing similar and

Abstract

The invention relates to a method for producing a single / bipolar plate, said method comprising the following steps:-uncoiling a material web from an uncoiler and supplying said uncoiled material web in the feeding direction of said material web to a nip between two rollers, at least one of said two rollers being a three-dimensional structured roller; and-guiding the uncoiled material web, maintaining the feed direction, through a nip between two rollers, at least one of the two rollers being a three-dimensional structured roller in which a flow channel geometry is embossed into the material web. When the flow channel geometry is embossed into the material web, a channel arrangement of parallel flow channel channels is created in the material web, where the parallel flow channel channels extend parallel to the feed direction. The invention also relates to a corresponding roller device for carrying out the method.

Description

[0001] The present invention relates to a method and a roller arrangement for producing a single and bipolar plate. A method according to the preamble of claim 1 is known from US 2017 / 0348811 A1.

[0002] The production of metallic, but also graphite-based, single and bipolar plates places high demands on the flatness and uniformity of the web guide. Proper web guidance is essential to ensure this. To this end, US 2017 / 0348811 A1 discloses guiding the material web through the nip tangentially to the two rollers forming the embossing gap.

[0003] To increase the efficiency of fuel cells, the density of the flow field channels of bipolar plates needs to be further increased, which requires, among other things, further reducing the distance between adjacent parallel flow field channels. This places high demands on the wrinkle-free and fold-free production of the flow field geometries at the highest possible feed rates during the roll forming process.

[0004] To achieve this object, a method according to claim 1 and a roller arrangement according to claim 13 are proposed. Advantageous embodiments of the invention are the subject matter of the respective dependent claims.

[0005] A single bipolar plate is one half of a bipolar plate, wherein two joined single bipolar plates can form a bipolar plate. The material web can in particular be and / or include a metal sheet (e.g., made of stainless steel) or a graphite web (e.g., made of expandable graphite). The expandable graphite web can be compacted during the described roll-forming process, thereby increasing its mechanical strength in addition to embossing the flow channel geometry. This is described in US 2017 / 0348811 A1.

[0006] The uncoiler can be braked to maintain the web tension. To this end, the uncoiler can be braked by a brake device on the uncoiler.

[0007] By means of the brake, the material web can be fed to the embossing nip with an optimal web tension, since the rotationally driven roller pair draws the material film into the embossing nip and the braked unwinder generates a counteracting holding force.

[0008] The uncoiler may be decelerated depending on the rotational speed of the roller pair or depending on the detected tension of the material web such that a desired tension value is achieved.

[0009] It can be provided that after the pair of rollers the material web is rolled up onto another roller or separated into individual bipolar plates by a separation step.

[0010] It can also be set that after passing through the nip in the feed direction, the material web is supplied to the cutting process, wherein holes are optionally introduced and / or the outer contour of the respective single- and double-sided plates is formed (especially cut) in the area of the respective single- and double-sided plates. For this purpose, the material web can be drawn out of the nip after the material web is substantially tension-free or when the web tension is much lower than the web tension used when the material web is supplied to the nip after uncoiling.

[0011] According to a second aspect, the present invention relates to a single- and double-sided plate which has been produced using an embodiment of the described production method.

[0012] The following drawings are used to explain further details of the present invention. Specifically: Figure 1 A first embodiment of the roll equipment is shown; Figure 2 A second embodiment of the roll equipment is shown; Figure 3 Shows for Figure 1 or Figure 2 An exemplary embodiment of the embossing roll in a pair of rolls according to Figure 4 An exemplary embodiment of the bonding structure is shown; and Figure 5 A further exemplary embodiment of the bonding structure is shown.

[0013] Metal bipolar plates but also graphite-based bipolar plates have high requirements for flatness and uniformity. To ensure this, proper web guiding is necessary. Figure 1 A roll equipment is shown, which has an uncoiler a and a pair of rolls b with two embossing rolls, and the pair of rolls can be designed as a punch and a die. Optimal results can be achieved using tangential web guides. In this case, braking is performed with a force F1 before the embossing gap (for example, at the uncoiler a), while the embossing unit pulls with a force F2 to overcome the braking force.

[0014] The web speed of the metal web is optionally 0 m / min < v1 < 300 m / min. The web tension ensures wrinkle-free embossing of the bipolar plate. At the exit gap, the web is preferably conveyed without web tension. However, it is also possible to convey the web using a slight web tension F3. In order not to change the embossing (for example, the length of the embossing) and to ensure further processing of the web, in principle F3 << F1. For example, if the web tension F3 is too high, it is impossible or very difficult to punch holes in the web. Deflection rolls or floating roll units can also shift the embossing in the web.

[0015] As Figure 1 shown in the embodiment Figure 2In the illustrated embodiment, the stretching force is generated via a pulling device. The material web is guided from the unwinder a to a braked friction roller c. In this variant, the braking force F1 can be precisely controlled and is therefore particularly suitable for flow field geometries with circumferential flow field alignment. However, flow field geometries in any other direction can also be embossed without wrinkles or creases.

[0016] Tensile stress is calculated as follows: Tensile stress = force F1 / material web cross-sectional area.

[0017] For a stainless steel material web, the tensile stress is preferably 100 N / mm 2 , and for titanium material webs, the tensile stress preferably exceeds 50 N / mm 2 .

[0018] If the material web is a graphite web, it may preferably comprise expandable graphite and / or consist of expandable graphite. Alternatively, the graphite web may comprise impregnated expandable graphite and / or consist of impregnated expandable graphite. The graphite web may comprise a polymer highly filled with graphite.

[0019] Figure 3 A schematic diagram showing a shell surface or drum surface with an engraved flow channel geometry perpendicular to the axial direction of the embossing roller (in particular, the axial direction of the embossing roller) is shown. Roller 1 has the embossed structure of a bipolar plate. The structured shell surface also has structural elements 2 for media openings. The material web has a width 3. Auxiliary engraved embossing is formed in area 4 on the structured shell surface. The engraved flow channel geometry has an embossed structure 5 for forming flow channel channels.

[0020] To prevent the material web from slipping under particularly high tensile stresses, auxiliary embossing 4 is formed on roller 1. The auxiliary embossing 4 can be arranged outside the embossed structure of the bipolar plate. Furthermore, the auxiliary embossing 4 can be formed in the area of ​​the media openings 2 to prevent wrinkling in the embossing in this area. The auxiliary embossing 4 can be at least as wide as the material web, wider than the material web, or even narrower.

[0021] It can happen that the two embossing rollers are pushed out of position by the embossed structure of the bipolar plate. This can lead to an uneven embossing pattern or even cuts in the embossing. The auxiliary embossing 4 can counteract this effect with a suitable geometry.

[0022] All geometric structures that return the roller to a defined position during embossing are suitable for assisting embossing. For example, pyramids can be designed as geometric structures ( Figure 4 ; I, II). However, other elements such as truncated cones or simple lines are also possible ( Figure 4: III). The lines may have a triangular shape in cross section, for example in a plane perpendicular to the longitudinal direction, which is optionally perpendicular to the axial direction and / or parallel to the circumference of the embossing roller or at different angles to the longitudinal direction.

[0023] A pyramid with a protruding tip can be provided on one of the two rollers. A concave counterpart can be formed on the other roller so that if there is a slight misalignment, the embossing force will guide the embossing back into registration. The same applies to linear arrangements. The flank angle β can be 0° < β <= 90°.

[0024] It is also possible to construct the auxiliary embossing on separate rings. These rings can be attached to the outside of the roller, in particular the embossing roller.

[0025] The auxiliary embossing may also have flattened pyramids and / or pyramids rotated 45°. Figure 5 ) can be 1 mm to 10 mm. The element height can be 0.05 mm to 3 mm. In addition, calendering of the material web can be avoided.

[0026] Figure 4 Possible forms of auxiliary embossing are shown: I and II show top views of pyramidal guide elements, with protruding locations marked in white and recessed areas in black. III shows an example of a linear arrangement on the left / right side of the guide element. IV shows an example line pattern (white: protruding; black: recessed). The cross-section of the linear embossing can be triangular.

[0027] The features of the invention disclosed in the above description, the drawings and the claims are essential for the realization of the invention in its various embodiments, both individually and in any combination.

Claims

1. A method for producing a monopolar plate and a bipolar plate, the method comprising the following steps: - unwinding a material web from an unwinder and supplying the unwinded material web in a feed direction of the material web to a nip between two rollers, at least one of which is a three-dimensionally structured roller; - guiding the unwound material web through a nip between two rollers while maintaining the feed direction, at least one of the two rollers being a three-dimensional structured roller, wherein a flow channel geometry is embossed into the material web; Characterized in that, when the flow channel geometry is embossed into the material web, a channel arrangement of parallel flow channels is produced in the material web, wherein the parallel flow channels extend parallel to the feed direction. 2 . The method according to claim 1 , wherein the material web is guided tangentially to the two rollers during feeding.

3. The method according to claim 1 or 2, wherein the material web is removed from the roll nip after being guided tangentially to the two rolls.

4. A method according to claim 3, wherein the material web is drawn out from the roll gap after the material web is rendered essentially tension-free or at a web tension much lower than the web tension used when the material web was supplied to the roll gap after unwinding.

5. The method according to any one of the preceding claims, wherein a metal foil or a graphite sheet, preferably an expandable graphite sheet or a polymer-filled graphite sheet, is uncoiled from the uncoiler.

6. The method according to any of the preceding claims, wherein the material web is unreeled from the uncoiler during unreeling while maintaining web tension oriented in the feed direction.

7. The method of claim 6, wherein the uncoiler is braked to maintain the web tension.

8. The method according to claim 6, wherein the uncoiler is substantially free-running and the material web uncoiled from the uncoiler is supplied to the roller gap in the feed direction via a pulling device, which provides and maintains the web tension in the feed direction.

9. A method according to claim 8, wherein the material web is deflected on a brake friction roller in the pulling device, wherein the material web is preferably wrapped around the brake friction roller along at least 30%, particularly preferably at least 40% and very particularly preferably at least 50% of the circumference of the brake friction roller.

10. A method according to claim 9, wherein the material web is deflected on a support roller in the feed direction of the material web from the uncoiler to the braked friction roller, wherein the support roller preferably has an adjustable distance relative to the braked friction roller so that the degree of wrapping of the material web around the friction roller can be adjusted.

11. Method according to any of the preceding claims, wherein at least one of the two rollers between which the roller nip is formed is driven in its direction of rotation.

12. The method according to any of the preceding claims, wherein the material web is conveyed in the feed direction at a web speed of between 0 and 300 m / min.

13. A roller apparatus for producing monopolar plates, wherein the roller apparatus comprises a decoiler, from which a material web is supplied in a feed direction to a roller gap between two rollers and is guided through the roller gap while maintaining the feed direction, wherein at least one of the two rollers is a three-dimensional structured roller and the two rollers are configured to emboss a flow channel geometry having a channel arrangement with parallel flow channels into the material web.

14. The roller apparatus according to claim 13, wherein the embossing structure comprises a plurality of parallel and elongated structural elements for embossing the flow channel, the plurality of parallel and elongated structural elements extending in the circumferential direction of the at least one structured roller.

15. Roller apparatus according to claim 13 or 14, wherein the material web is supplied tangentially to the two rollers, and wherein the material web is preferably drawn out of the roller gap in the feed direction behind the roller gap while keeping the feed direction tangential to the two rollers.

16. A roller device according to any one of claims 13 to 15, wherein the material web is drawn out from the roller gap in the feed direction essentially without tension behind the roller gap, or with a web tension in the feed direction that is much smaller than the web tension with which the material web is fed from the uncoiler to the roller gap.

17. Roller apparatus according to any one of claims 13 to 16, wherein the material web is and / or comprises a metal foil or a graphite web, preferably an expandable graphite web or a web made of polymer-filled graphite.

18. Roll apparatus according to any one of claims 13 to 17, wherein the material web has a web tension oriented in the feed direction upstream of the nip.

19. The roller apparatus of claim 18, wherein the uncoiler a. Slow down or b. The material web running substantially free and unwound from the unwinder is fed to the nip in the feed direction via a pulling device, wherein the pulling device is adapted to provide and maintain the web tension in the feed direction.

20. A roller device according to claim 19, wherein the material web is deflected on the brake friction roller in the pulling device, wherein the material web is preferably wrapped around the brake friction roller along at least 30% of the circumference of the brake friction roller, particularly preferably at least 40% and very particularly preferably at least 50%.

21. A roller device according to claim 20, wherein the material web is deflected on a support roller in the feed direction of the material web from the uncoiler to the brake friction roller, wherein the support roller preferably has an adjustable distance relative to the brake friction roller so that the degree of wrapping of the material web around the friction roller can be adjusted.

22. Roller apparatus according to any one of claims 13 to 21, wherein at least one of the two rollers forming the roller nip between them is driven in its direction of rotation.

23. A roller apparatus according to any one of claims 13 to 22, wherein at least one of the two rollers forming the roller gap has an adhesive structure on its roller shell, wherein the adhesive structure is designed to increase the coefficient of friction between the roller having the adhesive structure and the material web compared to a smooth roller shell.

24. Roller apparatus according to claim 23, wherein the roller shell, at least in some areas of the roller shell outside the structured area for embossing the flow channel geometry, has an increased coefficient of friction compared to the structured area.

25. Roller apparatus according to claim 24, wherein the region with the increased coefficient of friction surrounds, preferably completely encloses, the structured region on at least two opposing sides.

26. A roller device according to any one of claims 23 to 25, wherein the bonding structure has an embossed structure, the embossed structure having a plurality of regularly or randomly arranged embossed protrusions, wherein the embossed protrusions preferably have a linear shape with a preferably triangular cross-section, a pyramidal or cone-shaped geometry or a truncated pyramidal or truncated cone-shaped geometry.

27. Roller arrangement according to any one of claims 13 to 26, wherein the rollers between which the roller gap is formed are designed as embossments which are paired at least with respect to structured areas on their roller shells for embossing flow channel geometries.

28. Roller device according to any one of claims 23 to 27, wherein the roller is designed as a paired concave and convex mold in the area of ​​the bonding structure, in particular when the bonding structure is designed as an embossed structure with a plurality of regularly or randomly arranged embossing protrusions.

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