Abstract
The invention proposes a method for connecting plate-like components of a bipolar plate, comprising the steps of placing a first plate-like component on a clamping surface, placing a second plate-like component onto the first plate-like component, fitting a plurality of hold-down devices on an outer surface of the second plate-like component, said outer surface facing away from the first plate-like component and the clamping surface, wherein an envisaged seam line is kept free between the hold-down devices, pressing of the plate-like components together using all of the hold-down devices, wherein, for this purpose, a magnetic force acting in the direction of the clamping surface is applied to at least one of the hold-down devices, and welding the plate-like components along the seam line in a continuous operation.
Claims
1. A method for connecting plate-like components (4, 6) of a bipolar plate, comprising the following steps: placing (76) a first plate-like component (4) on a clamping surface (10), placing (78) a second plate-like component (6) onto the first plate-like component (4), fitting (80) a plurality of hold-down devices (12, 14, 16, 32, 34, 74) on an outer surface of the second plate-like component (6), said outer surface facing away from the first plate-like component (4) and the clamping surface (10), wherein an envisaged seam line (22) is kept free between the hold-down devices (12, 14, 16, 32, 34, 74), pressing (82) of the plate-like components (4, 6) together using all of the hold-down devices (12, 14, 16, 32, 34, 74), wherein, for this purpose, a magnetic force acting in the direction of the clamping surface (10) is applied to at least one of the hold-down devices (12, 14, 16, 32, 34, 74), and welding (84) the plate-like components (4, 6) along the seam line (22) in a continuous operation.
2. The method according to claim 1, wherein the welding (86) includes laser welding.
3. The method according to claim 1, wherein the fitting (80) of hold-down devices (12, 14, 16, 32, 34, 74) includes arranging at least one inner hold-down device (14) within the seam line (22) and at least one hold-down device (12, 16, 32, 34, 74) outside the seam line (22), and wherein the magnetic force is applied to the at least one inner hold-down device (14).
4. A system (2, 62) for connecting plate-like components (4, 6) of a bipolar plate, comprising: a clamping plate (8) having a clamping surface (10), a plurality of hold-down devices (12, 14, 16, 32, 34, 74) for pressing two plate-like components (4, 6) on the clamping surface (10), at least one magnetic unit (18), and a welding apparatus (24), wherein the at least one magnetic unit (18) is arranged on a side of the clamping surface (10) facing away from the hold-down devices (12, 14, 16, 32, 34, 74), wherein the at least one magnetic unit (18) is configured so as to apply a magnetic force to at least one of the hold-down devices (12, 14, 16, 32, 34, 74) so that the at least one hold-down device (12, 14, 16, 32, 34, 74) is pressed in the direction of the clamping surface (10), wherein the hold-down devices (12, 14, 16, 32, 34, 74) are configured to keep an envisaged seam line (22) between the hold-down devices (12, 14, 16, 32, 34, 74) in a state of being pressed onto the plate-like components (4, 6), and wherein the welding apparatus (24) is configured to weld the plate-like components (4, 6) along the seam line (22).
5. The system (2, 62) according to claim 4, wherein the hold-down devices (12, 14, 16, 32, 34, 74) comprise at least one outer hold-down device (12, 16, 32, 34, 74) and at least one inner hold-down device (14), wherein the at least one inner hold-down device (14) is configured to enclose the seam line (22) to the at least one outer hold-down device (12, 16, 32, 34, 74).
6. The system (2, 62) according to claim 4, wherein the at least one inner hold-down device (14) comprises at least two segments (36) that are mechanically coupled together.
7. The system (2, 62) according to claim 4, wherein the at least one inner hold-down device (14) comprises at least two segments (40) that are mechanically independent from one another.
8. The system (2, 62) according to claim 4, wherein the at least one hold-down device (12, 14, 16, 32, 34, 74) comprises at least one projection (52, 54) for engaging with a recess (56) of the plate-like components (4, 6).
9. The system (2, 62) according to claim 4, wherein at least one of the hold-down devices (12, 14, 16, 32, 34, 74) is chamfered on a region adjacent to the envisaged seam line (22) in a direction facing away from the seam line (22).
10. The system (2, 62) according to claim 4, wherein the magnetic unit (18) comprises at least one electromagnet.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) Further measures improving the invention are described in more detail below on the basis of the figures, together with the description of the preferred embodiment examples of the invention.
(2) FIG. 1 a schematic view of a system in a lateral section
(3) FIG. 2 a top view of the system
(4) FIGS. 3 to 5, the system with segmented inner hold-down
(5) FIGS. 6a and 6b different flow fields on the plate-like components
(6) FIGS. 7 to 10 detailed sectional views of the system
(7) FIG. 11 a modification of the system for line manufacturing
(8) FIG. 12 a schematic, block-based view of the method.
DETAILED DESCRIPTION
(9) FIG. 1 shows a system 2 for connecting two plate-like components 4 and 6 of a bipolar plate. For this purpose, the system 2 comprises a clamping plate 8 having a clamping surface 10. Further, a plurality of hold-down devices 12, 14, and 16 are provided in order to press the two plate-like components 4 and 6 on the clamping surface 10. While the laterally outer hold-down devices 12 and 16 shown in the drawing plane can also be pressed in the direction of the clamping plate 8 by a mechanical tensioning or retaining device, the inner hold-down device 14 is pushed by a magnetic force in the direction of the clamping plate 8. For this purpose, a magnetic unit 18 is arranged below the clamping plate 8. If the hold-down devices 12, 14 and 16 are at least partially formed from a magnetic material, they are attracted by the magnetic unit 18. Here, they press onto the plate-like components 4 and 6 with a respective abutment portion 20. An envisaged seam line 22 is fixed on both sides in a close-knit manner so that there is locally flush contact between the two plate-like components 4 and 6. A welding apparatus 24, which is configured by way of example as a laser welding apparatus and emits a laser beam 26, can weld the two plate-like components 4 and 6 along the seam line 22.
(10) To follow the arbitrarily shaped seam line 22, the welding apparatus 24 can rotate, for example, about two axes and/or can be moved translationally along two axes. To sufficiently keep free the seam line 22, the side edges 28 of the hold-down devices 12, 14, and 16 are chamfered in a direction facing away from the seam line 22. In order to avoid welding the plate-like components 4 and 6 with the clamping plate 8, a recess 30 is also provided below the envisaged seam line 22.
(11) In FIG. 2, the system 2 is shown in an aerial view. Here, the two lateral hold-down devices 12 and 16 are shown as elongated components that are parallel to and spaced apart from one another. They can be supplemented by additional hold-down devices 32 and 34, which run perpendicularly thereto and are also arranged parallel to and spaced apart from one another. The inner hold-down device 14 is provided in the form of a rounded rectangle. The hold-down devices 12, 14, 16, 33, and 34 enclose the envisaged seam line 22, which also has the shape of a rounded rectangle, by way of example.
(12) In FIG. 3, a modification is shown in which the inner hold-down device 14 is divided into a plurality of segments 36 and 40. The two segments 36 at left in the drawing plane are mechanically coupled to one another by a respective coupling spring 38. This can be a compression or tension spring configured so as to push into a predetermined neutral position. The two segments 40 arranged at right in the drawing plane are independent from the other segments 36 and also do not communicate with other components. Thus, for example, they could be guided via guide geometries arranged on the second plate-like component 6 or formed therein through the flow field arranged thereon.
(13) In FIG. 4 a further modified variant is shown, in which a plurality of segments 36 and 40 are provided, which are mechanically coupled or independently configured. The segments 36 and 40 each have a recess 42 through which the aforementioned welding apparatus 24 can carry out punctiform welding, approximately in the form of one top-stitch each.
(14) The shape fidelity can thus be improved in particular for larger bipolar plates. In FIG. 5, the sectional planes B-B and C-C are marked, which denote the cutaway views in FIGS. 7 and 8, in which the top-stitch and the orientation are more easily seen.
(15) FIGS. 6a and 6b each show a flow field 44 and 46 comprising flow channels 48 for supplying reagents and discharging reaction products. The flow field 44 shown in FIG. 6a comprises flow channels 48 that run in directions perpendicular to one another. The flow field 44 is consequently a cross-flow field. The flow field 46 in FIG. 6b, on the other hand, comprises flow channels 48 with exclusively parallel courses, so that it can be referred to as a counter-flow flow field. If a segment 40 is applied on one of the flow fields 44 or 46, shape features of the flow channels 48 can be used for the alignment. While the flow field 44 of FIG. 6a allows for a slight orientation in two spatial directions, this is only readily possible in one spatial direction for the flow field 46. However, if individual flow channels 48 have locally different heights, shape features can thereby be created at which a precise alignment in two spatial directions is possible.
(16) FIG. 7 shows the sectional plane B-B. There, a lateral hold-down device 36 with the recess 42 can be seen, through which the laser beam 26 can produce a top-stitch 50.
(17) In FIG. 8, the hold-down device 36 is shown, possessing a plurality of projections 52 and 54, which mesh with recesses 56 of the first plate-like component 6 and align the hold-down device 36 with them. In this case, the projections 52 are dimensioned such that they indeed project into the recesses 56 but do not touch the second plate-like component 6. This is done only at the projection 54, so as to establish a defined surface contact only there.
(18) FIG. 9 shows the inner hold-down device 14, whose application portion 20 is centered on flanks 58 of the second plate-like component 6. The inner hold-down device 14 can thereby be precisely placed on the second plate-like component and consequently arranged inside the edge of the envisaged seam line 22.
(19) FIG. 10 shows the inner hold-down device 14 with a projection 59, whose cross-section is rounded at its outer end and engages with a rounded recess 60 of the second plate-like component 6. With the rounded shape, a simple self-centering occurs and can sometimes prevent a tilting when the inner hold-down device 14 is applied.
(20) FIG. 11 illustrates a possible further development in the form of a continuous system 62 for the line manufacturing of bipolar plates. Here, a plurality of clamping plates 8 are guided continuously at a first conveyor unit 64. Along a utility path 66, the clamping plates 8 can be equipped (see II) with fed plate-like components 4 and 6 (see I). Then, hold-down devices 74 are fed (III) and placed on the plate-like components 4 and 6 (IV). A magnetic force is applied (V) to the hold-down device 74, and then the welding of the two plate-like components 4 and 6 (VI) occurs. Subsequently, the hold-down devices 74 are detached (VII) so that resulting bipolar plates 68 (VIII) can be removed (IX). The hold-down devices 74 can be transported via a second conveyor unit 70, which could continue to transport and lay additional magnetic clamping plates 72, which can also be used for carrying the hold-down devices 74.
(21) Finally, FIG. 12 shows the schematic representation of the method according to the invention. The following steps occur here: placing 76 a first plate-like component 4 on a clamping surface 10, placing 78 a second plate-like component 6 onto the first plate-like component 4, fitting 80 a plurality of hold-down devices on the second plate-like component 6 on a side facing away from the first plate-like component 4 and the clamping surface 10, wherein an envisaged seam line 22 is kept free between the hold-down devices. Then, the following steps occur: a pressing 82 of the plate-like components 4, 6 together using all of the hold-down devices, wherein, for this purpose, a magnetic force 84 acting in the direction of the clamping surface 10 is applied to at least one of the hold-down devices. Finally, the welding 86 of the plate-like components 4, 6 occurs along the seam line 22 in a continuous operation.
