Method and corresponding apparatus for manufacturing bipolar plates, unipolar plates, or separator plates for electrolytic cells and the like.
The method addresses inefficiencies in roll forming by staging notch creation before and after roll forming, ensuring precise notch formation and maintaining the integrity of the roll-formed structure, thereby improving fuel cell efficiency.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- MATTHEWS INTERNATIONAL GMBH
- Filing Date
- 2024-03-22
- Publication Date
- 2026-04-14
AI Technical Summary
Roll forming processes for manufacturing bipolar, unipolar, and separator plates in electrolytic cells face inefficiencies due to obstacles in forming small cutouts, particularly those with a small opening cross-section, leading to deformation of the embossed structure and reduced fuel cell efficiency.
A method involving a roll-to-roll, roll-to-sheet, or roll-to-product process is employed, where notches are formed in multiple stages, with smaller notches created before roll forming and larger notches after, using specific roll-to-roll units and cutting units to maintain the roll-formed structure and prevent deformation.
This approach maintains the integrity of the roll-formed structure, enhancing the efficiency of fuel cell performance by minimizing deformation and ensuring precise notch formation without compromising the channel structure.
Smart Images
Figure 2026511471000001_ABST
Abstract
Description
Technical Field
[0001] The present invention is based on a method for manufacturing bipolar plates, unipolar plates, separator plates, etc. for electrolytic cells, etc., according to the preamble of claim 1, as described in DE102010048761A1. A similar method is also described in WO2018 / 115952A1.
Background Art
[0002] Regarding the formation of the surface structure of a bipolar plate, unipolar plate, or separator plate having a flow field, it is known to process a material web by roll forming. For this purpose, a punching tool consisting of two parts, for example, a pair of rollers designed according to the male - female principle, can be used. In this way, the channel structure of the flow field can be formed in the material web. Furthermore, additional structural elements are formed to provide, for example, a fluid connection between the flow field and the cutouts of the bipolar plate, through which reaction gases and other reactants involved in the fuel cell reaction are induced. Such cutouts include, for example, fuel inlets, fuel outlets, oxidant inlets, oxidant outlets, coolant inlets, and coolant outlets. Subsequently, by stacking a plurality of bipolar plates, these cutouts form channels for the supply and discharge of reactants or coolant.
[0003] The cutouts of the plate are provided, for example, by a processing step following roll forming, i.e., cutting. In many cases, the cutting of the bipolar plate is not always carried out in a rotational manner. In this case, roll cutting or roll punching of the material web may lead to obstacles in the channel structure and other structuring of the material web formed during the previous roll forming, and thus to a loss of efficiency of the fuel cell. This obstacle to roll forming is particularly significant in the case of small cutouts, i.e., cutouts with a small opening cross - section, or cutouts where the cross - sectional area in one direction is much smaller than that in the direction perpendicular thereto.
[0004] Therefore, an object of the present invention is to further develop the above method so that the shape of the roll forming can be maintained when using a roll-to-roll, roll-to-sheet, and / or roll-to-product method for manufacturing notches. [Overview of the Initiative]
[0005] In the sense of the present invention, a roll-to-roll system is understood to mean that a material web, particularly one that is continuously guided, is supplied to at least two consecutive rolls and / or roll arrangements.
[0006] In the sense of the present invention, the roll-to-sheet method is understood to mean that a continuously guided material web is fed into a roll and / or roll arrangement, and that individual elements are manufactured from the material web either in this roll and / or roll arrangement or downstream of this roll and / or roll arrangement, and these are specifically supplied to further processing steps for manufacturing the final product.
[0007] In the sense of the present invention, the roll-to-product method is understood to mean that a continuously guided material web is supplied to a roll and / or roll arrangement, and that individual elements are manufactured from the material web or downstream of this roll and / or roll arrangement, and are the final product of the method, without requiring any additional processing steps.
[0008] This objective is achieved by a method having the features of claim 1. A corresponding apparatus is the subject of claim 18. Advantageous embodiments are described in the dependent claims. Furthermore, claim 2 covers an electrolytic cell comprising elements manufactured by the described method.
[0009] Therefore, in detail, the present invention provides a method for manufacturing bipolar plates, unipolar plates, separator plates, etc., the following steps which can be performed in different orders: - To provide a material web made of metal or graphite, and / or a polymer-based material web, - Roll forming of the material web, - A cutting of a material web, wherein a plurality of notches are formed during roll forming or are manufactured within or adjacent to a region of the material web in which a portion has been formed, the cutting is further carried out in a roll-to-roll, roll-to-sheet, or roll-to-product manner, preferably roll punching and / or roll cutting.
[0010] It is proposed that at least one of the notches is manufactured before roll forming, and / or that the roll-to-roll method, roll-to-sheet method, and / or roll-to-product method be carried out in two steps, using a first step in which at least one notch is manufactured before roll forming, and a second step in which at least one additional notch is manufactured after roll forming.
[0011] Furthermore, it is preferable that at least one notch manufactured before roll forming has a smaller opening cross-section than the opening cross-section of at least one further notch manufactured after roll forming.
[0012] In the embodiments described above, it is preferable that the opening cross-section of at least one additional notch manufactured after roll forming is at least twice, preferably at least four times, and particularly preferably at least eight times larger than the opening cross-section of at least one notch manufactured before roll forming.
[0013] The method according to the present invention may be characterized in that, in the second step, a bipolar plate formed in the preceding method step, including a flow field, is cut out from the material web, in addition to at least one further notch.
[0014] It is proposed that the fabrication of at least one further notch and the cutting of the bipolar plate from the material web be carried out in the same step.
[0015] Alternatively, it is proposed that at least one of the notches be manufactured after roll forming.
[0016] Furthermore, all notches may be manufactured before roll forming, and preferably, the bipolar plate may be fully formed within the material web after roll forming.
[0017] The method according to the present invention classifies notches manufactured by a roll-to-roll, roll-to-sheet, or roll-to-product method into one of at least two categories based on their respective opening cross-sectional areas, and assigns an opening cross-sectional area region to each category.
[0018] It is also proposed that the opening cross-sectional area regions do not overlap, or overlap but preferably do not coincide, and / or that neither region is a true subset of at least one other region of the region.
[0019] In the two embodiments described above, it is preferable that the roll-to-roll, roll-to-sheet, or roll-to-product method is carried out within different roll-to-roll units, roll-to-sheet units, or roll-to-product units in which the material web is conveyed to at least two of the two categories.
[0020] It is proposed that the manufacturing of notches of the first category of these categories be carried out in a first roll-to-roll unit, roll-to-sheet unit, or roll-to-product unit located upstream of the roll forming in the material web supply direction, and this first category is assigned to notches among a group of notches that have an opening cross-sectional area smaller than the opening cross-sectional areas of all the remaining notches combined.
[0021] It is even more preferable that the roll-to-roll, roll-to-sheet, or roll-to-product method for the second category to which the remaining notches are at least partially allocated is performed within a second roll-to-roll unit, roll-to-sheet unit, or roll-to-product unit located downstream of the first roll-to-roll unit in the material web supply direction.
[0022] A preferred embodiment of this method may provide that a second roll-to-roll unit is positioned upstream or downstream of the roll forming in the material web supply direction.
[0023] The manufacturing of the first category of these notches is preferably carried out in a first roll-to-roll unit, roll-to-sheet unit, or roll-to-product unit located downstream of the roll forming in the material web supply direction, and the first category in particular is assigned to notches among a plurality of notches that have an opening cross-sectional area smaller than the opening cross-sectional area of all the remaining notches combined.
[0024] It is proposed that a roll-to-roll, roll-to-sheet, or roll-to-product method for a second category to which the remaining notches are at least partially allocated is carried out within a second roll-to-roll unit, roll-to-sheet unit, or roll-to-product unit located upstream or downstream of the first roll-to-roll unit in the material web supply direction.
[0025] Finally, the method includes cutting a bipolar plate from a material web, preferably in a third roll-to-roll unit located downstream of the roll forming and all other roll-to-roll units in the material web supply direction.
[0026] The present invention further provides, preferably, an apparatus for manufacturing bipolar plates, unipolar plates, separator plates, etc. for performing the above method. The apparatus comprises the following functional units: - at least one unwinder for providing a material web made of metal or graphite, or a polymer-based material web, - at least one roll forming unit for roll-forming the material web, - at least one roll-to-roll unit, roll-to-sheet unit, or roll-to-product unit for roll-punching or roll-cutting the material web, wherein the roll-to-roll unit, roll-to-sheet unit, or roll-to-product unit is designed to manufacture a plurality of cutouts within the region of the material web formed during roll forming or within a region adjacent to this region.
[0027] It is also proposed that for the apparatus, at least one roll-to-roll unit, roll-to-sheet unit, or roll-to-product unit is arranged upstream of the roll forming unit in the supply direction of the material web.
[0028] It is also proposed that for the apparatus, at least one roll-to-roll unit, roll-to-sheet unit, or roll-to-product unit is arranged downstream of the roll forming unit in the supply direction of the material web.
[0029] Finally, the present invention provides an electrolytic cell comprising at least one bipolar plate, at least one unipolar plate, and / or at least one separator plate, wherein the bipolar plate, unipolar plate, and / or separator plate is manufactured by the method according to the present invention.
Brief Description of the Drawings
[0030] [Figure 1] [Figure 2] [Figure 3] [Figure 4] [Figure 5] [Figure 6] [Figure 7] [Figure 8] [Figure 9] [Figure 10] [Figure 11] [Figure 12] [Figure 13] [Figure 14] [Modes for carrying out the invention]
[0031] Further details of the present invention are illustrated with reference to the following figures. None of the examples described are intended to limit the present invention. Features described with reference to the individual figures may be used in any combination to realize an embodiment of the present invention not expressly shown in the figures, provided that they do not conflict with each other. In particular, features of individual embodiments may be omitted.
[0032] Rotary cutting tools are commonly used in the packaging industry to cut individual packages from material webs. Cutting is performed at speeds of up to 600 m / min. Until now, bipolar plates had not been cut using a rotary process.
[0033] In the manufacture of bipolar plates, unipolar plates, or separator plates (metal-based, graphite-based, and / or polymer-based) using roll-to-roll, roll-to-sheet, and / or roll-to-product methods, it is necessary to cut out notches for liquid transport and to cut out bipolar or unipolar plates that are embossed throughout.
[0034] Figure 1 shows an example of a conventional bipolar plate with a notched region, where the size of the notched region varies depending on the plate design. The notches are classified according to their size, in this case into small and medium classes.
[0035] When the plate design is relatively simple, it is possible to cut out all the necessary parts in one piece, as shown in Figure 2. However, it has been found that if all notches of any size are manufactured in a single process using a roll-to-roll method, the embossed structure can be deformed by cutting small notches into an already roll-formed sheet.
[0036] This embodiment describes a roll-to-roll method, but the present invention may alternatively or additionally include a roll-to-sheet method and / or a roll-to-product method.
[0037] To solve this problem, in the embodiment shown in Figure 3, it is proposed to first create small notches using a first roll-to-roll method before roll forming, and only then emboss the structure by roll forming. In a second roll-to-roll method following roll forming, or in the second step of the roll-to-roll method, medium-sized notches can be created, and the entire plate can be cut out with a separate cutting unit. It is also possible to cut out the medium-sized notches and the entire plate with separate cutting units. Depending on the plate design and roll arrangement, it may be advantageous to cut out the medium-sized notches before roll forming, as shown in Figures 4 and 5.
[0038] Figure 6 shows various possible plate orientations on a cutting roller for manufacturing notches using a roll-to-roll method. The top row shows rectangular plates; in the upper left modification, the plates are aligned circumferentially; in the upper center modification, the plates are aligned axially; in the upper right modification, the plates are inclined with respect to the axial or circumferential direction; and in the lower center modification, the plates are designed in a parallelogram shape.
[0039] The alignment of the plate on the cutting tool may be axial or circumferential. It is also possible to tilt the plate so that long cutting lines are eliminated in the axial direction. This can be beneficial for the cutting process by avoiding high axial line loads (as shown in the upper center of Figure 6). The plate can also be designed as a parallelogram (lower center of Figure 2). Then, the plate can be positioned as shown in the lower center of Figure 6 (or in another arrangement) to reduce line loads during the cutting process. In the modified version shown in the upper right of Figure 6, line loads are also reduced. Register control is useful for maintaining consistency between embossing and cutting the plate in a multi-stage process.
[0040] In the packaging industry, as shown in Figure 7, cutting tools often use punch lines to cut materials. Here, a distinction is made between cutting against a punched surface (a) and cutting against a punched element (b). In modification (a), the punch line applies pressure to the material web until the material tears and is pushed to the side. In this case, the opposing surface is flat. According to (b), it is also possible to use a punched element as the opposing surface. The cutting effect is better compared to modification (a), but the wear on the cutting tool is greater. Both modifications (a) and (b) can be used to cut metal, but the force that must be applied is much greater.
[0041] One of the cutting tools, according to the modified examples (c) to (f) shown in Figure 8, is more suitable for metal. The distance between the cutting elements is denoted by k and is between 1 μm and 20 μm. There are four particularly preferred embodiments of the cutting edge, which will be described with reference to Figures 9 to 12.
[0042] Figure 9 shows one embodiment with rectangular cutting elements (c). A rectangular die can be used to cut a metal sheet. The distance between the cutting elements is represented by k, and is between 1 μm and 20 μm. The rectangular shape is robust against wear but susceptible to tool misalignment.
[0043] Figure 10 shows one embodiment comprising a rectangular cutting element and an angled cutting element (d), where the cutting element includes an "alpha" angle to further improve metal cutting. "Alpha" can be between 0° and 45°. However, this arrangement is susceptible to tool alignment errors. The advantage of this arrangement is that the material web is pushed aside during cutting, making material removal easier.
[0044] Figure 11 shows one embodiment with two angled cutting elements (e). If a small misalignment occurs, the surfaces of the cutting elements slide against each other, preventing the cutting edge from breaking. Both sides of the material web are pushed out from the cutting position.
[0045] Figure 12 shows one embodiment with two angled cutting elements (f) having an additional bevel. This configuration is similar to embodiment (e), except that one or both cutting elements have an additional bevel. The bevel is expressed as an angle "beta" and can be between 1° and 90°. This additional bevel allows for better material removal after cutting.
[0046] Figure 13 shows an embodiment with a butterfly cut (g), where the two angles "alpha" and "beta" point in opposite directions compared to embodiments (d) to (f). The range of "alpha" and "beta" is preferably 0° to 45°. This embodiment provides the cleanest cut of the material web, particularly when the material web is made of or contains metal, provided that the removed material is not extruded. Furthermore, misalignment of the tool can cause significant damage to the cutting edge.
[0047] After embodiments of preferred cutting shapes have been described with reference to the previous figure, preferred shapes of cutting lines will be described with reference to the following figure. Parallel cutting lines may fail when long axial cuts are made (see Figure 6, upper left and upper center). Here, long axial cuts lead to high line loads, which must be compensated for by the cutting unit. To avoid high line loads, advantageous cutting edge shapes will be described with reference to Figure 14. Figure 14 shows a side view of a roller having different cutting elements, (h): triangular cutting element, (i): oblique cutting element, (j): corrugated or zigzag cutting element. Here, the cutting elements are shown in a plane perpendicular to those shown in (c) to (g).
[0048] In embodiment (h), the cutting tip is positioned in the center of the element from which the cutting begins. In embodiment (i), the cutting tip begins cutting from the side of the element being cut. In embodiment (j), the element being cut has multiple ridges from which the cutting begins. Both embodiments (h) and (i) require a very tall cutting edge to achieve a bevel across the entire element being cut. This results in a greater height for the element. Embodiment (j) uses multiple ridges to begin the cutting and requires a lower cutting element height compared to (h) and (i). On the other hand, embodiment (j) may result in an unclean cutting result. Embodiments (h) to (j) can be used in combination and / or used on both cutting edges of the same element.
[0049] All cutting elements can be directly integrated into the roller material or designed as replaceable segments. The advantages of using replaceable segments are the ability to replace individual segments / cutting elements if damaged and the possibility of readjusting individual elements if cutting performance deteriorates (e.g., due to wear).
[0050] The features of the present invention disclosed in the above description, figures, and claims may be essential to the implementation of the invention, either individually or in any combination.
Claims
1. A method for manufacturing bipolar plates, unipolar plates, separator plates, etc., the method comprising the following steps, which may be performed in different orders: - To provide a material web made of metal or graphite, and / or a polymer-based material web, - Roll forming the aforementioned material web, - The cutting of the material web, wherein a plurality of notches are formed during the roll forming, or are manufactured within or adjacent to a region of the material web in which such notches have been formed, The method is characterized in that the cutting is performed in a roll-to-roll manner, a roll-to-sheet manner, or a roll-to-product manner, preferably by roll punching and / or roll cutting.
2. The method according to claim 1, wherein at least one of the notches is manufactured before the roll forming, and / or the roll-to-roll method, roll-to-sheet method, and / or roll-to-product method is carried out in two steps, using a first step of manufacturing the at least one notch before the roll forming and a second step of manufacturing at least one further notch after the roll forming.
3. The method according to claim 2, wherein the at least one notch manufactured before the roll forming is manufactured with an opening cross-section smaller than the opening cross-section of the at least one further notch manufactured after the roll forming.
4. The method according to claim 3, wherein the opening cross section of the at least one further notch produced after roll forming is at least twice, preferably at least four times, and particularly preferably at least eight times larger than the opening cross section of the at least one notch produced before roll forming.
5. The method according to any one of claims 2 to 4, wherein in the second step, a bipolar plate formed in the preceding method step including a flow field is cut out from the material web, in addition to the at least one further notch.
6. The method according to claim 5, wherein the manufacturing of the at least one further notch and the cutting of the bipolar plate from the material web are performed in the same method step.
7. The method according to claim 1, wherein at least one of the notches is manufactured after the roll forming.
8. The method according to claim 1, wherein all of the aforementioned notches are manufactured before the roll forming, and preferably the bipolar plate is completely formed within the material web after the roll forming.
9. The method according to any one of the prior claims, wherein the notches, manufactured by the roll-to-roll, roll-to-sheet, or roll-to-product method, are classified into at least one of two categories based on their respective opening cross-sectional areas, and each category is assigned an opening cross-sectional area region.
10. The method according to claim 9, wherein the opening area regions do not overlap, or overlap but preferably do not coincide, and / or none of the regions are a true subset of at least one other region.
11. The method according to claim 9 or 10, wherein the roll-to-roll, roll-to-sheet, or roll-to-product method is carried out in different roll-to-roll units, roll-to-sheet units, or roll-to-product units in which the material web is conveyed to at least two of the at least two categories.
12. The method according to claim 11, wherein the manufacturing of the first category of notches is carried out in a first roll-to-roll unit, roll-to-sheet unit, or roll-to-product unit located upstream of the roll forming in the material web supply direction, and the first category is assigned to notches among the plurality of notches having an opening cross-sectional area smaller than the opening cross-sectional areas of all the remaining notches.
13. The method according to claim 12, wherein the roll-to-roll, roll-to-sheet, or roll-to-product method for a second category of the categories to which the remaining notches are at least partially allocated is performed in a second roll-to-roll unit, roll-to-sheet unit, or roll-to-product unit located downstream of the first roll-to-roll unit in the material web supply direction.
14. The method according to claim 13, wherein the second roll-to-roll unit is positioned upstream or downstream of the roll forming in the material web supply direction.
15. The method according to claim 11, wherein the manufacturing of the first category of notches is carried out in a first roll-to-roll unit, roll-to-sheet unit, or roll-to-product unit located downstream of the roll forming in the material web supply direction, and in particular, the first category is assigned to notches among the plurality of notches having an opening cross-sectional area smaller than the opening cross-sectional areas of all the remaining notches.
16. The method according to claim 15, wherein the roll-to-roll, roll-to-sheet, or roll-to-product method for a second category of the categories to which the remaining notches are at least partially allocated is performed within a second roll-to-roll unit, roll-to-sheet unit, or roll-to-product unit located upstream or downstream of the first roll-to-roll unit in the material web supply direction.
17. The method according to any one of the prior claims, comprising cutting the bipolar plate from the material web, wherein the cutting is performed in a third roll-to-roll unit located downstream of the roll forming and all other roll-to-roll units in the material web supply direction.
18. Preferably, an apparatus for manufacturing bipolar plates, unipolar plates, separator plates, etc., for carrying out the above method, wherein the apparatus comprises the following functional units: - At least one unwinder for providing a material web made of metal or graphite, or a material web based on a polymer, - At least one roll forming unit for roll forming the material web, - The apparatus comprising at least one roll-to-roll unit, roll-to-sheet unit, or roll-to-product unit for roll punching or roll cutting the material web, wherein the roll-to-roll unit, roll-to-sheet unit, or roll-to-product unit is designed to produce a plurality of notches within a region of the material web formed during roll forming, or within a region adjacent to such region.
19. The apparatus according to claim 18, characterized in that the at least one roll-to-roll unit, roll-to-sheet unit, or roll-to-product unit is positioned upstream of the roll forming unit in the material web supply direction.
20. The apparatus according to claim 18, characterized in that the at least one roll-to-roll unit, roll-to-sheet unit, or roll-to-product unit is positioned downstream of the roll forming unit in the material web supply direction.
21. An electrolytic cell comprising at least one bipolar plate, at least one unipolar plate, and / or at least one separator plate, wherein the bipolar plate, the unipolar plate, and / or the separator plate are manufactured by the method described in claims 1 to 17.