WO2023131468A1 - Procédé de soudage laser d'une plaque de champ d'écoulement d'une pile à combustible, ayant un bain de fusion produit à l'aide d'une pluralité de points laser - Google Patents

Procédé de soudage laser d'une plaque de champ d'écoulement d'une pile à combustible, ayant un bain de fusion produit à l'aide d'une pluralité de points laser Download PDF

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Publication number
WO2023131468A1
WO2023131468A1 PCT/EP2022/085024 EP2022085024W WO2023131468A1 WO 2023131468 A1 WO2023131468 A1 WO 2023131468A1 EP 2022085024 W EP2022085024 W EP 2022085024W WO 2023131468 A1 WO2023131468 A1 WO 2023131468A1
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WIPO (PCT)
Prior art keywords
laser
spots
individual beams
plate parts
ensemble
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PCT/EP2022/085024
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German (de)
English (en)
Inventor
Oliver BOCKSROCKER
Nicolai Speker
Tim Hesse
Philipp Scheible
Original Assignee
Trumpf Laser- Und Systemtechnik Gmbh
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Application filed by Trumpf Laser- Und Systemtechnik Gmbh filed Critical Trumpf Laser- Und Systemtechnik Gmbh
Priority to CN202280087853.6A priority Critical patent/CN118541233A/zh
Publication of WO2023131468A1 publication Critical patent/WO2023131468A1/fr

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
    • B23K26/02—Positioning or observing the workpiece, e.g. with respect to the point of impact; Aligning, aiming or focusing the laser beam
    • B23K26/06—Shaping the laser beam, e.g. by masks or multi-focusing
    • B23K26/0604—Shaping the laser beam, e.g. by masks or multi-focusing by a combination of beams
    • B23K26/0608—Shaping the laser beam, e.g. by masks or multi-focusing by a combination of beams in the same heat affected zone [HAZ]
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K2101/00—Articles made by soldering, welding or cutting
    • B23K2101/36—Electric or electronic devices

Definitions

  • the invention relates to a method for laser welding a bipolar plate for a fuel cell, two plate parts being welded to one another along at least one weld seam.
  • bipolar plates are used for the distribution of gases, in particular hydrogen and oxygen, the removal of water (water of reaction), the gas-tight separation between adjacent cells and the seal to the outside and cooling.
  • gases in particular hydrogen and oxygen
  • water water of reaction
  • the bipolar plate on the hydrogen side absorbs the electrons that are released and feeds them back to the oxygen side.
  • Such bipolar plates can have two metallic plate parts that are welded together.
  • weld seams must be fluid-tight lead to guide gases and water in defined paths.
  • weld seams serve to connect the two plate parts electrically and mechanically. It has become known from the subsequently published German patent application 10 2021 113 834.5 to produce at least one peripherally closed first weld seam with a first seam width and at least one second weld seam with a second seam width when laser welding plate parts of a bipolar plate, the second seam width being larger than the first seam width.
  • a method of the type mentioned at the beginning which is characterized in that the laser welding takes place along the at least one weld seam with a laser beam ensemble comprising at least three individual beams, the individual beams each generating a laser spot on a surface of the plate parts, and that the at least three individual beams of the laser beam ensemble produce a common melt pool in the plate parts.
  • a molten bath, with which the at least one weld seam of the plate parts of the bipolar plate is produced is not produced with a single laser beam, but with a laser beam ensemble comprising several individual beams (individual laser beams).
  • the laser spots generated by the individual beams are close enough together to create a common (continuous) melt pool in the plate parts. Since, within the scope of the method according to the invention, a plurality of laser spots jointly produce a single, common molten pool, the procedure according to the invention is also referred to as multi-spot welding with a mono molten pool.
  • the individual beams of the laser beam ensemble are applied at the same time and are guided together (synchronously) along the weld seam relative to the plate parts as part of a feed.
  • the weld can be made with fewer defects, in particular a significant reduction in microcracks in the weld can be achieved, especially at high ones Feed speeds, for example 1500 mm/s or more, or even 2000 mm/s or more.
  • the width B of the weld seam produced with the laser beam ensemble is typically at least 2 times as large, preferably at least 3 times as large , such as the largest laser spot diameter GDL in the laser beam ensemble (i.e. B>2*GDL or preferably B>3*GDL), in the direction transverse to the (local) welding direction.
  • a molten pool that is stable under the applied feed can be achieved, which solidifies in a uniform manner, so that the weld seam obtained has only few fluctuations in the seam quality over its length (in particular in the seam width or the welding depth).
  • Laser welding is carried out with high precision, especially in the welding regime. Accordingly, good (minimum) fluid tightness, and in particular gas tightness, of the weld seams of the bipolar plate can be ensured with high reliability.
  • the laser spots of the laser beam ensemble pass over the at least one welding seam completely (at least) once. If desired, additional crossings of the weld seam can be carried out with one or more laser beams, in particular again with an ensemble of laser beams, for example with the same ensemble of laser beams. Note that
  • the location of one or more laser beams (in particular a laser beam ensemble) of a pass can be determined based on the center of gravity of the laser power applied (on the workpiece surface). If only a single pass is used for laser welding the weld seam, the associated welding curve of the laser beam ensemble typically lies on the center line of the weld seam.
  • all crossings of the weld seam are preferably carried out with an ensemble of laser beams when producing a weld seam.
  • the several individual laser beams of the laser beam ensemble can be generated.
  • a laser source and several laser optics e.g. using a laser source with several light paths, among which the laser beam can be switched, with a different laser optic being connected to each light path via a fiber optic cable), or
  • Element for dividing an original laser beam into several laser beams e.g. B. Multifocal lens, optical wedge plate, diffractive optical element (DOE) or refractive optical element (ROE).
  • DOE diffractive optical element
  • ROE refractive optical element
  • the laser welding typically takes place as deep welding (that is to say with at least one vapor capillary; the vapor capillaries produced by the individual beams typically merge into one another at least in an upper region); in this way, in particular, a high feed rate can be achieved.
  • the laser welding of the plate parts arranged in an overlapping manner can be carried out as welding in or through welding.
  • the laser spots of the laser beam ensemble are preferably aligned in such a way that the orientation of the laser spots in relation to the feed direction can be arbitrary without noticeably influencing the laser welding (in particular with an equal power distribution between the laser spots); then cornering along the weld seam is particularly easy.
  • a specific orientation of the laser spots to the feed direction can also be specified (in particular with an unequal power distribution of the laser spots); when cornering along the weld seam, the laser beam ensemble must then also be rotated (for example by rotating a corresponding optical element for beam splitting into the individual beams).
  • the laser spots of the individual beams of the individual beams on the workpiece surface are preferably separate from one another, as a result of which intensity peaks due to superimposition of laser spots in the melt pool are avoided and the melt pool dynamics can be calmed down.
  • the individual beams produce adjacent laser spots on the workpiece surface (with respect to their laser spot centers).
  • the metallic plate parts of the bipolar plate are arranged overlapping for welding (typically with a congruent, aligned edge contour).
  • the plate parts of the bipolar plates typically have a profiling through which channels for cooling water and external guides can be formed between the plate parts. ments for water of reaction and/or gases, in particular hydrogen and oxygen, are formed.
  • the bipolar plates typically have one or more openings with which gas can be transported in the stack direction in the fuel cell stack.
  • the laser spot centers of the laser spots of the beam set are arranged in a ring formation.
  • the beam set can include three, four, five or six laser spots, for example.
  • the laser spot centers on the workpiece surface in a ring formation contribute to a smooth weld pool;
  • a directional dependency of the laser welding can be reduced with the laser beam ensemble.
  • the beam set may include all of the individual beams of the laser beam ensemble, or alternatively in addition to that
  • the laser beam ensemble can include one or more other individual beams.
  • a further development of this variant is particularly preferred, in which the laser spot centers of the radiation set form a regular polygon on the surface of the plate parts. As a result, the molten pool can be calmed further and the directional dependency can be further reduced.
  • a further development in which the laser spots of the radiation set are separate from one another on the surface of the plate parts is also advantageous. The laser spots of the beam set therefore do not overlap. This avoids local peaks in laser intensity, which means that the weld pool can be kept particularly quiet.
  • a further development is also preferred in which the laser spots of the radiation set have the same diameter and/or the individual beams of the radiation set have the same laser power. This also contributes to calming the weld pool and further reducing the directional dependency.
  • a further development is also advantageous which provides that for a distance a between the laser spot centers of adjacent laser spots in the ring formation: a ⁇ 10*GDR, with GDR: largest laser spot diameter in the ring formation.
  • GDR largest laser spot diameter in the ring formation.
  • the laser beam ensemble has a further individual beam, with a laser spot center of the further laser spot being arranged in a center of the ring arrangement of the beam set.
  • a laser spot center of the further laser spot is arranged in a center of the ring arrangement of the beam set.
  • an intensity minimum in the middle of the radiation set can be minimized, which can contribute to the stabilization of the (common) vapor capillary.
  • the further individual beam can have a different laser spot diameter (in particular a smaller laser spot diameter) than the laser spots of the beam set, and/or that the further individual beam can have a different laser power (in particular a smaller laser power) than the individual beams of the beam set. sets.
  • At least three further individual beams of the laser beam ensemble form an additional beam set, and that the laser spot centers of the laser spots of the additional beam set are arranged in an additional ring formation, with the additional ring formation is arranged concentrically with the ring formation, and wherein a respective distance of the laser spot centers of the laser spots of the additional ring formation to a center of the ring formation is smaller than a distance of the laser spot centers of the laser spots of the ring formation to the center of the ring formation.
  • the other individual beams can have a different laser power (in particular a lower laser power) than the individual beams of the beam set.
  • the laser spot centers of the additional ring formation typically form a regular polygon.
  • the diameters of the laser spots and the laser powers for the other individual beams of the additional beam set are all the same.
  • the laser spots of the additional beam set preferably do not overlap one another, but preferably they overlap with the laser spots of the beam set.
  • DZ ⁇ DS a maximum diameter of the laser spots of the additional set of rays and for a maximum diameter DS of the laser spots of the set of rays.
  • DZ ⁇ DS a maximum diameter of the laser spots of the additional set of rays
  • DZ ⁇ 0.5*DS or DZ ⁇ 0.3*DS also applies.
  • the additional laser power of the additional beam set can then be better concentrated on the area or areas of the beam set with low laser intensity, and the laser welding can take place with particularly high precision.
  • a variant of the method according to the invention is preferred, in which case for a maximum laser spot diameter GDL in the laser beam ensemble and for a smallest laser spot diameter KDL in the laser beam ensemble applies: KDL>l/10*GDL. This has proven itself in practice, especially in order to keep the expenditure on equipment low and to make a noticeable contribution to the heating of the melt pool even with small laser spots, without generating strong intensity peaks.
  • diameters of laser spots can generally be determined using the 86% criterion, according to which the diameter of a laser spot is determined in such a way that 86% of the total laser power of the associated individual beam (on the workpiece surface) is within a circle with it
  • a variant is particularly preferred in which the laser spots of the individual beams of the laser beam ensemble form an arrangement on a surface of the plate parts which has an N-fold rotational symmetry, with N>3.
  • N-fold rotational symmetry the laser spot arrangement is converted into itself with a rotation of 360°/N in each case.
  • the laser beam ensemble is divided by at least one optical element for dividing at least one primary laser beam is produced. This is a simple possibility in terms of apparatus to generate the laser beam ensemble or its individual beams.
  • the individual beams are in the form of superimposed individual laser beams, each comprising at least two partial beams which lie one inside the other on the surface.
  • a lower local laser power density is set up in a radially outer part of the superimposed individual laser beam and a locally higher power density is set up in a radially inner part of the superimposed individual laser beam.
  • a (local) vapor capillary in the area of the superimposed single laser beam can be stabilized during deep-penetration welding and the weld pool dynamics can be reduced.
  • the superimposed single laser beam typically has concentric partial beams on the workpiece surface. For the (outer) diameters dwinner (e.g.
  • the ratio dwinnemdwoutside is typically in the range of 1:1.1 to 1:6, preferably 1:3 to 1:5, particularly preferably 1:4.
  • KD: RD dwinnemdwoutside
  • the superimposed individual laser beam comprises a core beam and a ring beam that surrounds the core beam, or that the superimposed individual laser beam has a larger partial beam and a smaller partial beam that is located on the workpiece surface within the larger partial beam lies, includes. This procedure is particularly simple and has proven itself in practice.
  • a heterodyne single laser beam with core beam and ring beam is typically generated with a 2-in-1 fiber, and the core beam and ring beam have a common optical axis.
  • an original laser beam is guided in a multiclad fiber, comprising a core fiber and a ring fiber surrounding the core fiber, and that one from the Multiclad fiber exiting original laser beam is divided by means of an optical element on at least part of the individual beams.
  • the plate parts each have a sheet metal thickness BLD of between 50 ⁇ m and 150 ⁇ m.
  • the plate parts are preferably made of stainless steel, e.g. type 1.4404.
  • the sheet thickness BLD is preferably 75 ⁇ m.
  • Corresponding metallic plate parts can be produced inexpensively and are particularly well suited to the requirements in a bipolar plate of a fuel cell, in particular with regard to corrosion resistance, electrical conductivity and workability during laser welding. Sheet thicknesses between 50 pm and 150 pm combine sufficient robustness with a light and material-saving construction. 5
  • a variant of the method according to the invention is also preferred, where:
  • the individual beams are generated with an infrared laser and have a mean wavelength of between 800 nm and 1200 nm, preferably 1030 nm or 1070 nm, or the individual beams are produced with a VIS laser with a mean wavelength of between 400 nm and 450 nm or between 500 nm and 550 nm generated; and or
  • the respective beam parameter product SPP of the individual beams is between 0.38 mm*mrad and 16 mm*mrad, preferably with SPP ⁇ 0.6 mm*mrad, particularly preferably with SPP ⁇ 0.4 mm*mrad; and or
  • the laser power P per individual beam is between 10W and 2000W, preferably with 50W ⁇ P ⁇ 700W; and or
  • a feed VS of the laser beam ensemble is between 100 mm/s and 5000 mm/s, preferably with 300 mm/s ⁇ VS ⁇ 2000 mm/s; and or
  • An imaging ratio AV of laser optics, with which the individual beams are imaged onto the workpiece is between 1:1 and 5:1, preferably with 1.5:1 ⁇ AV ⁇ 2:1.
  • the at least one weld seam comprises one or more self-contained weld seams. Closed weld seams are usually used to seal off fluids in the fuel cell (cooling water, reaction water, reaction gases, e.g. hydrogen, oxygen). Within the scope of the invention, closed weld seams can be manufactured with improved tightness, which makes the invention particularly advantageous here. Also preferred is a variant in which the at least one weld seam comprises at least one closed weld seam running around the outside of the plate parts.
  • the closed weld seam running around the outside ensures in particular that no coolant (cooling water) escapes into the reaction chambers of a fuel cell stack, and no reaction gases (such as hydrogen and oxygen) can get between the plate parts or even mix in an uncontrolled manner. Accordingly, the improved tightness that can be achieved with the invention is of particular advantage here.
  • bipolar plate for a fuel cell produced by welding two plate parts according to the method according to the invention described above. manufactured in such a way Te bipolar plates are distinguished by good fluid tightness at the at least one weld seam, and by a good mechanical and electrical connection between the plate parts. Further advantages of the invention result from the description and the drawing. Likewise, the features mentioned above and those detailed below can be used according to the invention individually or collectively in any combination. The embodiments shown and described are not to be understood as an exhaustive list, but rather have an exemplary character for the description of the invention.
  • FIG. 1 shows a schematic plan view of a bipolar plate according to the invention with two plate parts which are connected to one another by a plurality of welded seams which are closed all the way round and a plurality of welded seams which extend in a straight line;
  • FIG. 2 shows a schematic top view of the welding of two plate parts of a bipolar plate according to a first variant of the invention, with a laser beam ensemble comprising three individual beams that form a beam set with three laser spots;
  • FIG. 3 shows three laser spots of a radiation set of a laser beam ensemble on a surface for welding two plate parts of a bipolar plate according to a second variant of the invention
  • FIG. 4 shows three laser spots of a radiation set and three further laser spots of an additional radiation set of a laser beam ensemble on a surface for welding two plate parts of a bipolar plate according to a third variant of the invention
  • 5 shows five laser spots of a radiation set of a laser beam ensemble on a surface for welding two plate parts of a bipolar plate according to a fourth variant of the invention
  • 6 shows three laser spots that are generated by three individual beams of a laser beam ensemble, the individual beams being designed as superimposed individual laser beams, for welding two plate parts of a bipolar plate according to a fifth variant of the invention
  • 7 shows a schematic representation of a forming arrangement for the invention in cross section, with which an exiting original laser beam can be provided for the method according to the invention
  • FIG. 8 shows an exemplary welding optics for dividing a primary laser beam into a laser beam ensemble for the method according to the invention.
  • FIG. 1 shows a schematic top view of a bipolar plate 1 according to the invention for a fuel cell not shown in detail here; the bipolar plate 1 shown was produced within the scope of a method according to the invention.
  • the bipolar plate 1 is made up of an upper plate part 1a and a lower plate part 1b.
  • the two plate parts la, lb of the bipolar plate 1 are arranged one above the other.
  • the two plate parts la, lb have a profile (not shown).
  • the profiling forms a system (e.g. a meandering or double meandering system) of different channels.
  • the channels between the two plate parts la, lb are cooling fluid channels (typically for cooling water).
  • the channels on the outer surfaces of the two plate parts la, lb are ducts for gas (such as oxygen or hydrogen) and water (which occurs as reaction water in the fuel cell).
  • the two plate parts la, lb are made of a metallic material, e.g. B. stainless steel.
  • a sheet thickness BLD of the plate parts 1a, 1b is 75 pm here; Sheet thicknesses of between 50 ⁇ m and 150 ⁇ m are generally preferred.
  • the two plate parts 1 a , 1 b are connected to one another by a large number of weld seams 2 (after application of the method according to the invention).
  • the weld seams 2 are shown schematically in dashed lines based on their center lines.
  • a circumferentially closed weld seam 2a runs on the outside of the two plate parts 1a, 1b.
  • Two closed weld seams 2b run around two openings 3, which extend through the bipolar plate 1.
  • Several open (here straight) welds 2c also run on the bipolar plate te 1.
  • the weld seams 2a, 2b are designed to be fluid-tight, in particular gas-tight.
  • the weld seams 2c are used for the mechanical and electrically highly conductive connection between the two plate parts 1a, 1b.
  • the present inventive method was applied to all welds 2a, 2b, 2c.
  • FIG. 2 shows a first variant of the method according to the invention, which is applied to the plate parts 1a, 1b of a bipolar plate 1 (as explained in FIG. 1).
  • the first variant is explained using weld seam 2a as an example.
  • the weld seam 2a in production is shown schematically in broken lines using its center line on a surface 4 ("workpiece surface"; upper side of the plate part 1a).
  • the weld seams 2b, 2c are also shown schematically in broken lines using their center lines.
  • the welding seam 2a is produced in the variant shown in FIG. 2 by means of a laser beam ensemble with three individual beams which are directed from above (perpendicular to the plane of the drawing) onto the upper plate part 1a.
  • the three individual beams of the laser beam ensemble together form a beam set.
  • the three individual beams of the beam set generate three laser spots 5a, 5b, 5c on the surface 4 of the two plate parts 1a, 1b.
  • the three laser spots 5a, 5b, 5c each have a laser spot center 6a, 6b, 6c.
  • the laser spots 5a, 5b, 5c overlap slightly in their edge regions.
  • the laser spots 5a, 5b, 5c of the radiation set are moved along a welding curve 8 as part of a feed (relative to a common center of gravity 7 of the laser spots 5a, 5b, 5c).
  • the welding curve 8 runs along the welding seam 2a (here on the center line of the welding seam 2a, the welding curve 8 is here identical to the center line of the welding seam 2a).
  • the direction of feed is marked with an arrow; the feed runs along a (local) welding direction SR.
  • the individual beams produce a common melt pool 9 of melted plate material.
  • the common melt pool 9 is widest. In contrast to the welding direction SR. the common molten pool 9 gradually becomes narrower.
  • At least three individual beams of the laser beam ensemble (or the individual laser spots 5a, 5b, 5c) generate a common melt pool 9.
  • the individual beams of the laser beam ensemble produce separate molten pools 9 that are separated from one another by plate material that has not been melted.
  • the weld seam 2a is completely produced in the variant shown.
  • the simultaneous action of the three individual jets allows for a better quality weld and a more precise weld;
  • the finished weld 2a can be made with fewer defects, and in particular, the weld 2a with few microcracks (compared to using only a single beam) can be obtained.
  • a comparatively wide weld seam 2a is produced, through which an improved mechanical and electrical connection between the plate parts la, lb
  • the individual beams of the laser beam ensemble can be generated with an optical element from a common original laser beam (see FIG. 8); the three individual beams are preferably also guided via a common scanning device.
  • the optical element can also be pivoted in curves of the weld seam 2a according to the curve, which enables a very compact construction (not shown in detail).
  • the laser spot 5a runs ahead and the laser spots 5b, 5c run behind. 0
  • Fig. 3 shows a schematic representation of three laser spots 5a, 5b, 5c of a beam set of three individual beams of a laser beam ensemble on a surface.
  • two plate parts of a bipolar plate can be welded with the three laser spots 5a, 5b, 5c.
  • the three laser spots 5a, 5b, 5c are all the same size here, and the diameter dw of the laser spots 5a, 5b, 5c on the workpiece is 100 ⁇ m in each case.
  • the three laser spot centers 6a, 6b, 6c are in the center of the three laser spots 5a, 5b, 5c.
  • the laser spots 5a, 5b, 5c are separate from one another here; they do not touch or overlap each other.
  • the laser power of the individual beams is chosen to be the same here.
  • an average power density of the three laser spots 5a, 5b, 5c on the surface is also the same here. In this way, a melt pool generated on the surface by the lasers 5a, 5b, 5c can be kept particularly still, since local peaks in the laser intensity of the laser beam ensemble are avoided.
  • the laser spots 5a, 5b, 5c are arranged in a ring formation 10 which encloses an inner surface.
  • the corner points of a regular polygon 11, here a regular triangle 11a can be defined by the laser spot centers 6a, 6b, 6c.
  • the distances a between the laser spot centers 6a, 6b, 6c from adjacent, i. H. in the ring formation 10 adjacent laser spot centers 6a, 6b, 6c are here each 108 pm.
  • all the laser spot centers 6a, 6b, 6c are next to one another.
  • the laser spot centers 6a, 6b, 6c of the laser spots 5a, 5b, 5c of the ring formation 10 lie here on a circular line 36 (shown in dashed lines) around the common center 12.
  • the ring arrangement 10 can calm the melt pool dynamics and reduce the directional dependency.
  • 4 shows a schematic representation of three laser spots 5a, 5b, 5c of a set of three individual beams and three laser spots 5a', 5b', 5c' of an additional set of three additional individual beams of a laser beam ensemble on a surface. With the three laser spots 5a, 5b, 5c and the three laser spots
  • two plate parts of a bipolar plate can be welded 5 5a′, 5b′, 5c′.
  • the three laser spots 5a, 5b, 5c of the beam set are all the same size here, and the diameters dw of the laser spots 5a, 5b, 5c on the workpiece are each 100 ⁇ m here.
  • the diameter dw is also the maximum
  • Diameter DS of the laser spots 5a, 5b, 5c of the beam set Diameter DS of the laser spots 5a, 5b, 5c of the beam set.
  • the three laser spot centers 6a, 6b, 6c are in the center of the three laser spots 5a, 5b, 5c.
  • the laser spots 5a, 5b, 5c are separate from one another here; they do not touch or overlap each other. 5
  • the three laser spots 5a', 5b', 5c' of the additional beam set are also all the same size here, and the diameter dw' of the laser spots 5a', 5b', 5c' on the workpiece is 20 ⁇ m here.
  • the diameter dw' is also the maximum diameter DZ of the laser spots 5a', 5b', 5c' of the
  • laser spots 5a', 5b', 5c' are three laser spot centers 6a', 6b', 6c'.
  • the laser spots 5a', 5b', 5c' touch each other exactly here.
  • laser spot 5a partially overlaps laser spot 5a'
  • laser spot 5b partially overlaps laser spot 5b'
  • laser spot 5c partially overlaps laser spot 5c'.
  • the distances a between the laser spot centers 6a, 6b, 6c of the adjacent laser spot centers 6a, 6b, 6c in the ring formation 10 are all the same size and are each 108 ⁇ m here.
  • the laser spots 5a', 5b', 5c' are arranged in an additional ring formation 10'.
  • the additional ring formation 10 ′ is arranged concentrically with the ring formation 10 .
  • the distances a' between the laser spot centers 6a', 6b', 6c' from the adjacent The laser spot centers 6a', 6b', 6c' lying next to one another, ie neighboring in the additional ring formation 10', are all of the same size and are each 20 ⁇ m here.
  • the distances a′ of the laser spot centers 6a′, 6b′, 6c′ of the laser spots 5a′, 5b′, 5c′ adjacent in the additional ring formation 10′ therefore correspond to the sum of the respective half diameters dw′ of the laser spots 5a′, 5b ', 5c'.
  • the laser spot centers 6a, 6b, 6c of the laser spots 5a, 5b, 5c of the ring formation 10 lie here on a circular line 36 (shown in broken lines) around the common center 12, corresponding to a regular polygon.
  • the laser spot centers 6a′, 6b′, 6c′ of the laser spots 5a′, 5b′, 5c′ of the additional ring formation 10′ also lie on a circular line (shown in dashed lines) around the common center 12 and correspond to the corners of a regular polygons.
  • the distances az of the laser spot centers 6a, 6b, 6c of the laser spots 5a, 5b, 5c of the ring formation 10 to the center 12 of the ring formation 10 are all the same size and are each 70 ⁇ m here.
  • the distances az′ of the laser spot centers 6a′, 6b′, 6c′ of the laser spots 5a′, 5b′, 5c′ of the additional ring formation 10′ to the center 12 of the ring formation 10 are also all the same and are each 12.5 ⁇ m .
  • FIG. 5 shows a schematic representation of five laser spots 5a, 5b, 5c, 5d, 5e of a beam set of five individual beams of a laser beam ensemble on a surface.
  • two plate parts of a bipolar plate can be welded with the five laser spots 5a-5e.
  • the five laser spots 5a-5e are all the same size here, and the diameter dw of the laser spots 5a-5e on the workpiece is 100 ⁇ m here.
  • the five laser spot centers 6a, 6b, 6c, 6d, 6e are located in the center of the five laser spots 5a-5e.
  • the laser spots 5a-5e are separate from each other here; they do not touch or overlap each other.
  • the laser spots 5a-5e are arranged in the ring formation 10, which includes an inner surface before.
  • the corner points of the regular polygon 11, here a regular pentagon 11b can be defined by the laser spot centers 6a-6e.
  • the distances a between the laser spot centers 6a-6e of the adjacent, i. H. in the ring formation 10 adjacent laser spot centers 6a-6e are each 140 pm here.
  • the laser spot centers 6a-6e of the laser spots 5a-5e of the ring formation 10 lie here on a circular line 36 (shown in dashed lines) around the common center 12.
  • the directional dependency is reduced even further compared to variants with fewer laser spots 5a-5e.
  • the laser beam ensemble is typically not rotated when cornering along the weld seam. Furthermore, a large width of the weld seam can be produced particularly easily.
  • Fig. 6 shows a schematic representation of three laser spots 5a, 5b, 5c of a beam set of three individual beams of a laser beam ensemble on a
  • the three individual beams are designed here as three superimposed individual laser beams.
  • two plate parts of a bipolar plate can be welded with the three laser spots 5a, 5b, 5c.
  • the superimposed individual laser beams here include a first partial beam and a second partial beam (not shown in detail).
  • the first sub-beam is designed as a core beam and the second sub-beam is designed as a ring beam; Core beam and ring beam can be generated by means of a multiclad fiber, for example.
  • the ring ray surrounds the core ray in a ring.
  • the three laser spots 5a, 5b, 5c which are generated on the surface by the superimposed individual laser beams, each have a core portion 13a, 13b, 13c and a ring portion 14a, 14b, 14c.
  • the ring portions 14a, 14b, 14c surround the core portions 13a, 13b, 13c in a ring shape.
  • the core parts 13a, 13b, 13c are all the same size and have a core diameter KD of 100 ⁇ m here.
  • the ring parts 14a, 14b, 14c are also all the same size and have a ring diameter RD of 400 ⁇ m here.
  • a respective ring diameter RD is four times larger than a respective core diameter KD.
  • the respective ring portion 14a, 14b, 14c has an area that is approximately 15 times larger than the respective core portion 13a, 13b, 13c.
  • An average power density in the respective core portion 13a, 13b, 13c is then about 15 times greater than an average power density in the respective ring portion 14a, 14b, 14c. In this way, a (local) vapor capillary generated by the superimposed individual laser beams can be stabilized in the deep welding regime and the dynamics of the melt pool can be reduced.
  • the three laser spots 5a, 5b, 5c are all the same size here, and the diameters dw of the laser spots 5a, 5b, 5c (which are equal to the ring diameters RD here) on the workpiece are each 400 ⁇ m here.
  • the three laser spot centers 6a, 6b, 6c are in the center of the three laser spots 5a, 5b, 5c.
  • the laser spots 5a, 5b, 5c touch each other here.
  • the laser power of the individual beams is chosen to be the same here.
  • the laser spots 5a, 5b, 5c are arranged in a ring formation 10.
  • the distances a between the laser spot centers 6a, 6b, 6c from the laser spot centers 6a, 6b, 6c are 400 ⁇ m in each case.
  • the laser spot centers 6a, 6b, 6c of the laser spots 5a, 5b, 5c of the ring formation 10 lie here on a circular line 36 (shown in broken lines) around the common strand 12 and correspond to the corner points of a regular polygon.
  • FIG. 7 shows a schematic longitudinal sectional view of a forming arrangement 37 for the invention, comprising a splitting device 15 and a multiclad fiber 16, which is designed here as a 2-in-1 fiber 16a.
  • a primary laser beam 17 is reshaped with the reshaping arrangement 37 .
  • the original laser beam 17 propagates along an axis Z.
  • the multiclad fiber 16 has a core fiber 18 (inner dotted area) and a cladding layer 19 surrounding the core fiber 18 (inner two dotted areas). Adjoining the cladding layer 19 radially outward is a ring fiber 20 (two outer dotted areas), which is surrounded by a further cladding layer 21 (two outer dotted areas).
  • the original laser beam 17 is generated by a laser source (not shown in detail).
  • the original laser beam 17 propagates in a collimated manner along the Z axis and is directed onto the splitting device 15 .
  • the splitting device 15 here comprises an optical wedge 15a and a focusing lens 15b.
  • a part of the original laser beam 17 is deflected with the optical wedge 15a and focused on the ring fiber 20 at a fiber input 22 of the multiclad fiber 16 with the focusing lens 15b.
  • Another part of the original laser beam 17 is guided past the optical wedge 15a and focused onto the core fiber 18 at the fiber input 22 of the multiclad fiber 16 with the focusing lens 15b.
  • the original laser beam 17 is coupled into the multiclad fiber 16 and at a fiber end 23 of the multiclad fiber 16 there is then an emerging original laser beam 17' with an original laser core beam 24 (continuous line at the fiber end 23) and an original laser ring beam 25 (dashed line at fiber end 23) provided for the method according to the invention.
  • the exiting, reshaped original laser beam 17' can now be divided into individual beams (cf. FIG. 8).
  • FIG. 8 shows a schematic longitudinal sectional view of an exemplary welding optics 26, with which a division of a original laser beam 17 (also a shaped original laser beam, cf. FIG. 7) into individual beams 33 for the method according to the invention can be carried out.
  • the welding optics 26 here includes a laser light cable 27 (for example a multiclad fiber as described in Fig. 7), a collimating lens 28, an optical element 29, which is formed here with two bifocal inserts 30a, 30b, and a focusing lens 31.
  • the bifocal inserts 30a , 30b which are designed here as glass wedges, are arranged one behind the other and rotated by 90° to one another.
  • the original laser beam 17 is provided via the laser light cable 27 and exits at a fiber end of the laser light cable 27 .
  • the end of the fiber is in the focus of the collimating lens 28, and the exiting original laser beam 17 is collimated by the collimating lens 28, as a result of which the original laser beam 17 becomes a collimated laser beam 32.
  • the collimated laser beam 32 is directed to the bifocal inserts 30a, 30b.
  • the bifocal inserts 30a, 30b each take up about half of a cross section of the collimated laser beam 32 here.
  • the collimated laser beam 32 can be divided into four individual beams 33 in the exemplary welding optics 26 shown here (two of the four individual beams 33 can be seen in the perspective shown here).
  • the four individual beams 33 form a laser beam ensemble 34 for laser welding a bipolar plate according to the invention.
  • the four individual beams 33 together form a beam set 35 of the laser beam ensemble 34.
  • the individual beams 33 are directed through the focusing lens 31 onto the surface of the plate parts of the bi- polar plate (not shown in detail), whereby four laser spots of equal size are generated on the surface. Depending on the optical element 29 used, fewer or more laser spots can also be generated on the surface (not shown in detail).

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  • Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Engineering & Computer Science (AREA)
  • Plasma & Fusion (AREA)
  • Mechanical Engineering (AREA)
  • Laser Beam Processing (AREA)

Abstract

L'invention concerne un procédé de soudage laser d'une plaque de champ d'écoulement (1) pour une pile à combustible, deux parties de plaque (1a, 1b) étant soudées l'une à l'autre le long d'au moins un cordon de soudure (2, 2a, 2b, 2c). Selon l'invention, le soudage laser est effectué le long de l'au moins un cordon de soudure (2, 2a, 2b, 2c) à l'aide d'un ensemble de faisceaux laser (34) comprenant au moins trois faisceaux individuels (33), les faisceaux individuels (33) produisant chacun un point laser (5a-5e, 5a'-5c') sur une surface (4) des parties de plaque (1a, 1b), et les au moins trois faisceaux individuels (33) de l'ensemble de faisceaux laser (34) produisent un bain de fusion commun (9) dans les parties de plaque (1a, 1b). L'invention concerne un procédé qui permet d'obtenir une bonne étanchéité aux fluides de cordons de soudure d'une plaque de champ d'écoulement avec une haute fiabilité.
PCT/EP2022/085024 2022-01-05 2022-12-08 Procédé de soudage laser d'une plaque de champ d'écoulement d'une pile à combustible, ayant un bain de fusion produit à l'aide d'une pluralité de points laser WO2023131468A1 (fr)

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CN202280087853.6A CN118541233A (zh) 2022-01-05 2022-12-08 激光焊接燃料电池双极板的方法，具有由多个激光光斑产生的熔池

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DE102022100187.3 2022-01-05
DE102022100187.3A DE102022100187A1 (de) 2022-01-05 2022-01-05 Verfahren zum Laserschweißen einer Bipolarplatte einer Brennstoffzelle, mit einem mit mehreren Laserspots erzeugten Schmelzbad

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20050252892A1 (en) * 2004-05-11 2005-11-17 Newman Keith E Laser welding of conductive coated metallic bipolar plates
WO2021005061A1 (fr) * 2019-07-08 2021-01-14 Trumpf Laser- Und Systemtechnik Gmbh Appareil optique et procédé de soudage au laser d'une pièce, comprenant plusieurs faisceaux partiels présentant une zone centrale et une zone annulaire dans le profil de faisceau
DE102021113834A1 (de) 2021-05-28 2022-12-01 Trumpf Laser- Und Systemtechnik Gmbh Bipolarplatte für eine Brennstoffzelle und Verfahren zum Schweißen einer Bipolarplatte
WO2023016719A1 (fr) * 2021-08-10 2023-02-16 Robert Bosch Gmbh Procédé de soudage et dispositif de soudage pour souder des éléments

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE10221951B4 (de) 2002-05-13 2004-04-22 Reinz-Dichtungs-Gmbh & Co. Kg Bipolarplatte und Verfahren zu deren Herstellung sowie Vorrichtung zur Durchführung des Verfahrens
CA3094699A1 (fr) 2018-03-30 2019-10-03 Furukawa Electric Co., Ltd. Procede de soudage et dispositif de soudage

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20050252892A1 (en) * 2004-05-11 2005-11-17 Newman Keith E Laser welding of conductive coated metallic bipolar plates
WO2021005061A1 (fr) * 2019-07-08 2021-01-14 Trumpf Laser- Und Systemtechnik Gmbh Appareil optique et procédé de soudage au laser d'une pièce, comprenant plusieurs faisceaux partiels présentant une zone centrale et une zone annulaire dans le profil de faisceau
DE102021113834A1 (de) 2021-05-28 2022-12-01 Trumpf Laser- Und Systemtechnik Gmbh Bipolarplatte für eine Brennstoffzelle und Verfahren zum Schweißen einer Bipolarplatte
WO2023016719A1 (fr) * 2021-08-10 2023-02-16 Robert Bosch Gmbh Procédé de soudage et dispositif de soudage pour souder des éléments

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