Manufacturing method for manufacturing a single bipolar plate

Abstract

The present invention relates to a manufacturing method for manufacturing a single bipolar plate (200). The manufacturing method comprises: unrolling a material film (100) from a roll (101); and passing the material film (100) through a pair of rollers (107), wherein a movement of the material film (100) in the direction of passage to the pair of rollers (107) is braked in front of the pair of rollers (107) in order to tension the material film (100), and wherein a three-dimensional contour is moulded into the material film (100) by the pair of rollers (107), said contour extending both linearly and in a curved manner on all three spatial axes, and wherein the contour comprises a flow field (201), the flow field channels of which extend transversely to the direction of passage of the material film (100).

Description

[0001] Description

[0002] Manufacturing process for producing a single bipolar plate

[0003] The presented invention relates to a manufacturing method for producing a single bipolar plate and a single bipolar plate.

[0004] Bipolar plates made of stainless steel are currently manufactured using hydroforming or translational stamping processes such as deep drawing or stamping. These processes form the sheet metal three-dimensionally. However, stamping processes, particularly in the production of bipolar plates, only involve two-dimensional forming. This means that the contour of the component only changes along two dimensional axes. In the third dimensional axis, the contour does not change but runs linearly across the entire component. This makes it possible to see through the entire contour along the Y-axis. Accordingly, the degree of forming is consistently the same across the entire Y-axis and does not change along the Y-axis. Therefore, the corresponding contours are not enclosed by a flat surface.

[0005] In two-dimensional transformations, there are also variants in which the contour also changes in the third dimension, but this only occurs through a combination of two-dimensionally transformed contours, each of which runs linearly along the third dimensional axis. In the third dimensional axis, the contours never run along a curve.

[0006] During three-dimensional forming, the contour of a component changes across all three spatial axes. Accordingly, the contours run both linearly and curved along all three spatial axes. The degree of forming therefore varies along all three spatial axes and is not consistently consistent along one axis. Forming contours can be enclosed by a flat surface. However, it is also possible that this surface is not flat but curved. It is impossible to see through the contour.

[0007] Furthermore, single bipolar plates are usually manufactured in a roll forming process in which the flow field and frame plate are machined separately, resulting in a two-part single bipolar plate, which in turn is time-consuming and material-intensive and correspondingly expensive.

[0008] Within the scope of the invention presented, a manufacturing method for a single bipolar plate and a single bipolar plate are presented. Further features and details of the invention emerge from the respective subclaims, the description, and the drawings. Features and details described in connection with the manufacturing method according to the invention naturally also apply in connection with the single bipolar plate according to the invention, and vice versa, so that with regard to the disclosure of the individual aspects of the invention, reference is always made to each other.

[0009] Against this background, it is an object of the invention presented to provide a possibility for the rapid and material-saving production of a single bipolar plate.

[0010] Thus, according to a first aspect of the invention, a manufacturing method for producing a single bipolar plate is presented. The manufacturing method comprises unwinding a material film, in particular a metal strip, from a roll and passing the material film through a pair of rollers. A movement of the material film in the direction of travel toward the pair of rollers is decelerated in front of the pair of rollers to tension the material film. A three-dimensional contour is formed into the material film by the pair of rollers, which contour extends both linearly and curvedly along all three spatial axes. The contour comprises a flow field whose flow field channels extend transversely to the direction of travel.

[0011] In this context, a single bipolar plate is one half of a bipolar plate, so that two single bipolar plates joined together form a bipolar plate.

[0012] In the context of the invention presented, a material film is understood to mean, in particular, a sheet made of, for example, stainless steel.

[0013] The presented manufacturing method is based on a three-dimensional forming process, i.e. a roll forming process in which a three-dimensional contour is formed into a material film. In order to prevent the material film from wrinkling during the forming process and to keep certain smooth areas free of wrinkles, the invention provides that the material film is decelerated in the direction of travel upstream of a pair of rollers used for forming, so that the material film is tensioned. Furthermore, it is provided that the contour comprises a flow field whose flow field channels run transversely to the direction of travel. Flow field channels running transversely to the direction of travel allow material to flow out of the material film from behind in each channel, which leads to minimal material thinning. This allows particularly high degrees of deformation to be achieved.

[0014] In contrast to transverse flow field channels, longitudinal flow field channels block each other and block material influence, whereby the material film thins more and more with increasing deformation.

[0015] The forming speed is generally a significant advantage of roll forming over hydroforming or translational stamping. Another advantage of roll forming is the very low forming forces due to the linear contact geometry of the rollers used. Furthermore, less material waste is possible than with hydroforming or stamping because a smaller holding surface is not required.

[0016] It may be provided that braking is carried out by a braking device on the roller.

[0017] By installing a braking device directly on a roll used to supply the film material, for example, in a tape unwinder, the film material can be kept completely "under tension" or under tension. Since the driven pair of forming rollers pulls the film material between the rollers and the tape unwinder counteracts this, a tape tension is created, i.e., a force that stretches the film material. The braking device can be adjusted to the rotational speed of the pair of rollers or, using a sensor that detects the mechanical tension of the film material, can be controlled to achieve a predetermined tension value.

[0018] It can further be provided that the belt tension is not generated by means of driven forming rollers but by a downstream driven belt winder and the pair of forming rollers only rotates.

[0019] It can further be provided that the braking device on the roll comprises a friction brake device, a magnetic brake device, or a motor rotating counter to the direction of travel or a motor rotating more slowly in the direction of travel than the pair of rollers. In particular, it can be provided that the motor runs and applies a braking torque. A friction brake device, such as a brake shoe, can be used to brake the roll or a corresponding tape unwinder. Alternatively, the roll can be rotated counter to the direction of travel or more slowly in the direction of travel using a magnet or a motor, such as an electric motor.

[0020] It can further be provided that the braking is carried out by a braking device which comprises a strip braking device, wherein the strip braking device comprises a friction brake which brakes the material film between the roll and the pair of rollers.

[0021] A friction brake that slows down the material film between the roll and the roller pair can adjust the tension applied to the roller pair very precisely, since length effects of the roll or the material film wound on the roll, such as a material strip or a metal band, are prevented or avoided during braking.

[0022] It can further be provided that braking is achieved by a braking device comprising brake rollers that rotate between the roller and the pair of rollers opposite to the direction of travel or that rotate in the direction of travel more slowly than the forming rollers, thereby braking the material film. Alternatively, the motor can rotate in the direction of travel and apply a braking torque.

[0023] A pair of brake rollers rotating counter to the direction of travel or rotating more slowly in the direction of travel is particularly suitable for adjusting a dynamically changing braking force. Accordingly, brake rollers can be used to respond effectively to a dynamically changing production process.

[0024] It can further be provided that the material film is wound onto another roll after the pair of rollers and, optionally, a further operation sequence for punching and trimming or is separated into individual bipolar plates by a separation step.

[0025] By rolling the formed material film onto a roll, transport and further processing of the corresponding individual bipolar plates is considerably facilitated, since individual bipolar plates are very fragile and can be easily damaged.

[0026] It can further be provided that a roller pair with at least one, in particular two, forming rollers is used, which has a number of mold cavities that have a negative contour of a single bipolar plate to be formed, through which material springback is deflected in order to obtain a dimensionally accurate component after forming. In the context of the presented invention, a mold cavity is understood to mean a complete impression of a single bipolar plate, which is machined into a respective roller. For example, it can be provided that the roller pair provided according to the invention comprises at least one, in particular two forming rollers, each comprising at least two, in particular six, ten, or twelve mold cavities.

[0027] It can further be provided that the material film is fed to a shaping process, in particular a cutting process, after the pair of rollers, in which perforations are introduced in the region of a respective individual bipolar plate and an outer contour of the respective individual bipolar plate is shaped, in particular cut.

[0028] Because the proposed manufacturing process is a one-piece, single-stage process, i.e., a single work sequence, each formed single bipolar plate blank can be fed through the material film, i.e., in a continuous process, to a further processing unit, such as a punch for forming, in particular, cutting perforations and an outer contour. Accordingly, after the further processing unit, a material film containing a multitude of finished single bipolar plates is created.

[0029] This can be achieved either by individually separated bipolar plates or by connecting individual bipolar plates in a continuous strip or film of material, which is then wound up into a roll.

[0030] According to a second aspect, the presented invention relates to a single bipolar plate, wherein the single bipolar plate is produced by a possible embodiment of the presented production method.

[0031] It may be provided that a flow field, a distribution area and a frame plate of the bipolar plate consist of a single piece of metal.

[0032] The three-dimensional forming process provided according to the invention allows a single bipolar plate to be manufactured from a single piece of metal.

[0033] Further advantages, features, and details of the invention will become apparent from the following description, in which exemplary embodiments of the invention are described in detail with reference to the drawings. The features mentioned in the claims and in the description may be essential to the invention individually or in any combination. Figure 1 shows a possible embodiment of the proposed manufacturing process.

[0034] Figure 2 shows a possible design of the presented bipolar single plate.

[0035] Figure 1 shows a schematic diagram of the presented manufacturing process.

[0036] Initially, a material film 100 is unwound from a roll 101 onto a tape unwinder 103. The material film 100 is guided to a pair of rollers 107 via a deflection roller 105. The pair of rollers 107 comprises a lower forming roller (male die) 109 and an upper forming roller (female die) 111, which form the material film 100 in a three-dimensional forming process.

[0037] The material film is guided via a further deflection roller 113 to a further processing device 115, which punches the material film 100 and processes it at the edges of the respective formed bipolar individual plates.

[0038] Finally, the material film 100 is either wound up on a tape winder 117 or cut into individual bipolar plates.

[0039] To keep the material film 100 under tension in the area of ​​the roller pair 107, the material film is braked in front of the roller pair 107, as indicated by arrows 119. The braking of the material film 100 can be achieved, for example, by a braking device on the tape unwinder 103 or by an additional roller pair (not shown here) that rotates more slowly in the direction of travel than the forming roller pair, indicated by arrow 121.

[0040] Figure 2 shows a single bipolar plate 200. The single bipolar plate 200 comprises a flow field 201 in which a pattern is formed that runs in a channel-like manner along the single bipolar plate's longitudinal axis, particularly linearly and curvedly in all three spatial axes.

[0041] Furthermore, the single bipolar plate 200 comprises a distribution region 210 and a plate frame 205, which, together with the flow field 201, are formed from a single piece of metal, into which a pattern is thus formed that runs linearly and curved in all three spatial axes, particularly in the region of a transition from the flow field 201 to the distribution region 210 or a region of a transition from the plate frame 205 to the flow field 201 or from the distribution region 210 to the plate frame 205. During production, the single bipolar plate 200 is guided through a pair of rollers such that channels formed in the flow field 201, as indicated by an arrow 207, run transversely to a flow direction indicated by arrow 209.

[0042] List of reference symbols

[0043] Material film

[0044] role

[0045] Tape unwinder

[0046] pulley

[0047] pair of rollers

[0048] male part

[0049] die

[0050] pulley

[0051] Further processing facility

[0052] Tape winder

[0053] Arrow

[0054] Arrow

[0055] Bipolar single plate

[0056] River field

[0057] Holes for media inlets

[0058] Plate frame

[0059] Arrow

[0060] Arrow

[0061] Distribution area

Claims

Patent claims Manufacturing method for producing a single bipolar plate (200), the manufacturing method comprising: Unrolling a material film (100) from a roll (101), Passing the material film (100) through a pair of rollers (107), wherein a movement of the material film (100) in the direction of passage to the pair of rollers (107) is braked in front of the roller pair (107) in order to tension the material film (100), and wherein a three-dimensional contour is formed into the material film (100) by the roller pair (107), which contour runs both linearly and curved on all three spatial axes, and wherein the contour comprises a flow field (201) whose flow field channels run transversely to the direction of travel. Manufacturing method according to claim 1, characterized in that the braking is carried out by a braking device on the roller (101). Manufacturing method according to claim 2, characterized in that the braking device (103) comprises a friction braking device, a magnetic braking device, or a motor rotating in the direction of travel slower than the forming roller pair. Manufacturing method according to claim 1, characterized in that the braking is carried out by a braking device which has a Strip braking device, wherein the strip braking device comprises a friction brake that brakes the material film (100) between the roller (101) and the roller pair (107). Manufacturing method according to claim 1, characterized in that the braking is carried out by a braking device that comprises brake rollers, which rotate between the roller (101) and the pair of rollers (107) in the direction of travel more slowly than the pair of forming rollers and thereby decelerate the material film (100). Manufacturing method according to one of the preceding claims, characterized in that the material film (100) is decelerated after the pair of rollers (107) and a Further processing device (115) is rolled up onto a further roll. Manufacturing method according to one of the preceding claims, characterized in that the material film (100) is separated into individual bipolar plates (200) by a separating step after the pair of rollers (107). Manufacturing method according to one of the preceding claims, characterized in that the material film (100) is separated into individual bipolar plates (200) after the pair of rollers (107) and a Further processing device (115) is rolled onto another roll. Manufacturing method according to one of the preceding claims, characterized in that the material film (100) is separated into individual bipolar plates by a separating step after the roller pair (107) and a further processing device (115). Manufacturing method according to one of the preceding claims, characterized in that a roller pair (107) with a forming roller (109, 111) is used, which has a number of mold cavities that have a negative contour of a single bipolar plate (200) to be formed, by which a material springback is bent over in order to obtain a dimensionally stable component after forming.Manufacturing method (100) according to one of the preceding claims, characterized in that the material film (100) is fed to a shaping process after the pair of rollers (107), in which perforations are introduced in the region of a respective single bipolar plate (200) and an outer contour of the respective single bipolar plate (200) is formed. Manufacturing method (100) according to one of the preceding claims, characterized in that the material film is tensioned by means of a tape winder (117) arranged downstream of the roller pair. Bipolar single plate (200), wherein the bipolar single plate (200) is manufactured by a manufacturing method according to one of the claims. Bipolar single plate (200) according to claim 13, characterized in that a flow field (201), a distribution region (210), and a plate frame (205) of the bipolar single plate (200) consist of a single piece of metal.

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