A fuel cell metal bipolar plate laser welding tool and welding device

Abstract

The application provides a fuel cell metal bipolar plate laser welding tool and a welding device, and relates to the technical field of fuel cells, and solves the technical problem that the welding tool cannot press the bipolar plate tightly, which causes the bipolar plate to be easy to warp. The welding tool comprises an upper pressing plate, a lower supporting plate, a turnover connecting rod mechanism and a lock catch assembly. The lower supporting plate is used for bearing two metal bipolar plates to be welded. The upper pressing plate is arranged on the lower supporting plate through the turnover connecting rod mechanism and can press the two metal bipolar plates. The lock catch assembly is arranged between the lower supporting plate and the upper pressing plate and has a locking state and a loosening state. When in the locking state, the upper pressing plate and the lower supporting plate can be positionally locked. When in the loosening state, the upper pressing plate can be separated from the locking position. The metal bipolar plate is arranged between the upper pressing plate and the lower supporting plate. The upper pressing plate presses the metal bipolar plate and is locked through the lock catch assembly, so that the upper and lower metal bipolar plates are closely attached and the bipolar plate is prevented from warping.

Description

Technical Field

[0001] This invention relates to the field of fuel cell technology, and in particular to a laser welding fixture and welding apparatus for fuel cell metal bipolar plates. Background Technology

[0002] Metal bipolar plates possess significant advantages as fuel cell bipolar plates due to their excellent electrical and thermal conductivity, machinability, fewer manufacturing steps, and mature technology. In the production of metal bipolar plates, welding is a critical process; appropriate laser welding process parameters and tight fit between the welded parts of the bipolar plate are essential factors in ensuring welding quality.

[0003] Currently, to ensure tight and flat welding of bipolar plates, tooling is often used to clamp the bipolar plates. However, due to machining limitations of the tooling, uneven force is often applied to the clamping area, resulting in ineffective clamping of the bipolar plates and severe deformation, which affects the subsequent sealing of the bipolar plates. Furthermore, existing technologies typically use screws, snap rings, pressure plates, and clips for physical contact clamping of metal bipolar plates. These methods are difficult to operate, prone to workpiece deformation, and have low production efficiency.

[0004] Currently, low-power laser welding is commonly used for bipolar plate welding to avoid the problem of bipolar plate warping caused by overheating during laser welding. However, low-power welding suffers from problems such as incomplete penetration in thick plates and weak bipolar plate welds. Therefore, it is necessary to develop a high-efficiency clamping and leveling welding fixture and welding method for addressing warping issues in laser welding of metal bipolar plates, in order to overcome the shortcomings of current technology. Summary of the Invention

[0005] The purpose of this invention is to provide a laser welding fixture and welding device for fuel cell metal bipolar plates, so as to solve the technical problem in the prior art that the welding fixture cannot press the bipolar plates tightly, resulting in the bipolar plates being prone to warping.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] This invention provides a laser welding fixture for metal bipolar plates in fuel cells, comprising an upper pressure plate, a lower support plate, a flipping linkage mechanism, and a locking assembly, wherein:

[0008] The lower support plate is used to support two metal bipolar plates to be welded;

[0009] The upper pressure plate is rotatably mounted on the lower support plate via the flipping linkage mechanism, which can press the two metal bipolar plates together.

[0010] The locking assembly is disposed between the lower support plate and the upper pressure plate, and has a locked state and a released state. When it is in the locked state, it can lock the position of the upper pressure plate and the lower support plate. When it is in the released state, it can release the upper pressure plate from the locked position.

[0011] As a further improvement of the present invention, the metal bipolar plate has positioning holes around its perimeter; the lower support plate has positioning bosses around its perimeter; the positioning bosses are engaged with the positioning holes to achieve positioning between the metal bipolar plate and the lower support plate.

[0012] As a further improvement of the present invention, the flipping linkage mechanism includes a connecting piece, a connecting shaft, and a hinge;

[0013] in:

[0014] The number of connecting pieces is two, which are respectively connected to the upper pressure plate and the lower support plate;

[0015] The two connecting pieces are respectively connected to the connecting rod shaft via hinges.

[0016] As a further improvement of the present invention, the hinge is a 180-degree rotating hinge.

[0017] As a further improvement of the present invention, the locking assembly includes a fixing block, a pressure block, a locking pin, and a locking nut; wherein:

[0018] The number of pressure blocks is two, which are respectively set at the top and bottom of the fixed block;

[0019] The pressure block, the upper pressure plate, and the lower support plate are provided with through holes;

[0020] After passing through the through hole, the locking pin is screwed to the locking nut at both ends.

[0021] As a further improvement of the present invention, a through welding path groove is provided on the upper pressure plate along the welding route.

[0022] As a further improvement of the present invention, the welding path groove includes a straight path groove that is a straight line and a serpentine path groove that is an S-shaped curve.

[0023] As a further improvement of the present invention, a plurality of welding grooves are formed on the metal bipolar plate corresponding to the welding path groove positions.

[0024] As a further improvement of the present invention, the welding groove includes a straight welding groove and a serpentine welding groove.

[0025] As a further improvement of the present invention, the straight welding groove is a stepped groove structure.

[0026] The present invention provides a welding apparatus, including a welding platform and a laser welding fixture for the metal bipolar plate of the fuel cell placed on the welding platform.

[0027] As a further improvement of the present invention, the welding platform is a magnetizable platform with adjustable magnetic attraction; the upper pressure plate is made of magnetically conductive material.

[0028] As a further improvement of the present invention, the lower support plate is made of a magnetically conductive material.

[0029] The welding fixture provided by this invention consists of an upper pressure plate, a lower support plate, a flipping linkage mechanism between the two plates, and a locking assembly. A metal bipolar plate is placed between the upper pressure plate and the lower support plate. The lower support plate has a positioning boss to fix the metal bipolar plate, and the upper pressure plate has a laser welding path groove. Simultaneously, the upper pressure plate can be closed and opened via the flipping linkage mechanism between the two plates, and the upper and lower plates can be pressed and locked together by the locking assembly. During welding of the metal bipolar plates, the two metal bipolar plates are fixed by the positioning boss on the lower support plate to prevent misalignment. At the same time, the upper pressure plate presses down on the metal bipolar plate and is locked by the locking assembly, ensuring a tight fit between the upper and lower metal bipolar plates and preventing warping.

[0030] During the welding process, the laser beam welds two metal bipolar plates through the welding path groove on the upper pressure plate. After welding, the upper pressure plate can be opened and closed by a flipping linkage mechanism, allowing the metal bipolar plates to be replaced without removing the upper pressure plate. This greatly improves the welding efficiency of the bipolar plates. Furthermore, by opening welding grooves on the metal bipolar plates and matching the welding path grooves on the tooling with the welding grooves on the metal plates, the welding efficiency is greatly improved. This ensures that the welding grooves on the bipolar plates and the welding tooling work together, while guaranteeing the mechanical strength and flow channel integrity of the bipolar plates. It also solves the problems of weak bipolar plate welding and plate warping, greatly improving the sealing performance and welding quality of the bipolar plates. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 This is a schematic diagram of the lower support plate in the laser welding fixture for fuel cell metal bipolar plates of the present invention;

[0033] Figure 2 This is a schematic diagram of the upper pressure plate in the laser welding fixture for fuel cell metal bipolar plates of the present invention;

[0034] Figure 3 This is a schematic diagram of the structure of the metal bipolar plate in the laser welding fixture for fuel cell metal bipolar plates of the present invention;

[0035] Figure 4 yes Figure 3 Enlarged view of part A in the middle;

[0036] Figure 5 This is a schematic diagram of the structure of the laser welding fixture for the metal bipolar plates of the fuel cell of the present invention when they are assembled together;

[0037] Figure 6 This is a schematic diagram of the locking assembly in the laser welding fixture for fuel cell metal bipolar plates of the present invention;

[0038] Figure 7 This is a schematic diagram of the structure of a linear welding groove in the laser welding fixture for fuel cell metal bipolar plates of the present invention;

[0039] Figure 8 This is a schematic diagram of the second embodiment of the linear welding groove in the laser welding fixture for fuel cell metal bipolar plates of the present invention;

[0040] Figure 9 This is a schematic diagram of the third embodiment of the linear welding groove in the laser welding fixture for fuel cell metal bipolar plates of the present invention;

[0041] Figure 10 This is a schematic diagram of the fourth embodiment of the linear welding groove in the laser welding fixture for fuel cell metal bipolar plates of the present invention;

[0042] Figure 11 This is a welding effect diagram of the bipolar plate after processing in Example 1 when using the laser welding fixture for fuel cell metal bipolar plates of the present invention.

[0043] Figure 12 This is a welding effect diagram of the bipolar plate after processing in Comparative Example 1, when the laser welding fixture for the metal bipolar plate of the fuel cell of the present invention is used.

[0044] In the diagram: 1. Lower support plate; 2. Positioning boss; 3. Upper pressure plate; 4. Straight path groove; 5. Serpentine path groove; 6. Metal bipolar plate; 7. Positioning hole; 8. Straight welding groove; 9. Connecting piece; 10. Connecting rod shaft; 11. Fixing block; 12. Pressure block; 13. Locking post; 14. Locking nut. Detailed Implementation

[0045] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be described in detail below. Obviously, the described embodiments are merely some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other implementation methods obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0046] This invention provides a simple and efficient laser welding fixture for metal bipolar plates 6 in fuel cells, used to weld metal bipolar plates 6 in two fuel cells; specifically, the welding fixture of this invention includes an upper pressure plate 3, a lower support plate 1, a flipping linkage mechanism, and a locking assembly, wherein:

[0047] like Figure 1 As shown, the lower support plate 1 is used to support two metal bipolar plates 6 to be welded. The lower support plate 1 is a quadrilateral plate structure with a planar surface.

[0048] like Figure 2 and Figure 5 As shown, the upper pressure plate 3 is rotatably mounted on one side of the lower support plate 1 via a flipping linkage mechanism. When flipped to be parallel to the lower support plate 1, it can press the two metal bipolar plates 6 together in preparation for welding. When flipped to be at a certain angle to the lower support plate 1, it can release the two welded metal bipolar plates 6, making it easy to remove the metal bipolar plates 6 from the welding fixture and replace them with new bipolar plates.

[0049] like Figure 6 As shown, the locking assembly is located between the lower support plate 1 and the upper pressure plate 3, and has a locked state and an unlocked state. When it is in the locked state, it can lock the upper pressure plate 3 and the lower support plate 1 in position, that is, it can keep the upper pressure plate 3 and the lower support plate 1 in a stable parallel pressing state, which facilitates the good welding of the metal bipolar plate 6. When it is in the unlocked state, it can release the upper pressure plate 3 from the locked position, that is, the upper pressure plate 3 can be lifted and flipped relative to the lower support plate 1.

[0050] The welding fixture provided by this invention consists of an upper pressure plate 3, a lower support plate 1, a flipping linkage mechanism between the two plates, and a locking assembly. A metal bipolar plate 6 is placed between the upper pressure plate 3 and the lower support plate 1. The upper pressure plate 3 can be closed and opened by the flipping linkage mechanism between the two plates, and the upper and lower plates can be pressed and locked together by the locking assembly. When welding the metal bipolar plate 6, the two metal bipolar plates 6 are fixed by the positioning boss 2 of the lower support plate 1 to prevent misalignment of the bipolar plates. At the same time, the upper pressure plate 3 presses down on the metal bipolar plate 6 and locks it by the locking assembly, so that the upper and lower metal bipolar plates 6 fit tightly together and prevent the bipolar plates from warping. This solves the problems of warping during welding of the metal bipolar plate 6, complex and inefficient bipolar plate clamping, and inaccurate positioning.

[0051] To prevent misalignment of the two metal bipolar plates 6 during welding, which could lead to misalignment of their flow channel structures, in this embodiment, the metal bipolar plates 6 have positioning holes 7 around their perimeter. Figure 3 As shown, specifically, there are eight positioning holes 7; six positioning bosses 2 are provided around the four sides of the lower support plate 1, specifically located at the four corners and two opposite sides of the lower support plate 1; the six positioning bosses 2 are respectively engaged with the six positioning holes 7, thereby achieving the positioning between the metal bipolar plate 6 and the lower support plate 1, and thus achieving the alignment of the two metal bipolar plates 6. It can be seen from the side that the flow channels on the two metal bipolar plates are completely aligned without misalignment. This effectively ensures the tight fit of the bipolar plate welding and prevents the metal bipolar plate 6 from being misaligned during welding.

[0052] It should be noted that since the positioning hole 7 is a rectangular structure, the positioning boss 2 is also rectangular, and the height of the positioning boss 2 is not less than the thickness of one metal bipolar plate 6 and not greater than the thickness of two metal bipolar plates 6.

[0053] The positioning boss 2 of the present invention is provided in the form of protruding from the lower support plate 1 and is integrally machined with the lower support plate 1. The positioning boss 2 is set according to the positioning hole 7 of the outer contour of the metal bipolar plate 6. By cooperating with the positioning hole 7 of the outer contour of the metal bipolar plate 6, the positioning boss 2 achieves the purpose of positioning and aligning the metal bipolar plate 6, thereby preventing misalignment during bipolar plate welding. The setting of the positioning boss 2 is conducive to the rapid positioning and alignment of the metal bipolar plate 6, effectively eliminating the welding misalignment problem in the welding of bipolar plates.

[0054] The present invention has a positioning boss 2 on the lower support plate 1, which can quickly and accurately position the welding part of the bipolar plate and effectively prevent the metal bipolar plate 6 from being misaligned during welding.

[0055] The welding fixture of the present invention has a positioning boss 2 on the lower support plate 1 for fixing the metal bipolar plate 6. This not only achieves the alignment and positioning of the two metal bipolar plates 6, but also does not interfere with the upper pressure plate 3, thus avoiding the problem of insufficient clamping.

[0056] like Figure 5 As shown, in an optional embodiment of the present invention, the flipping linkage mechanism includes a connecting piece 9, a connecting shaft 10, and a hinge; wherein:

[0057] There are two connecting pieces 9, which are connected to the upper pressure plate 3 and the lower support plate 1 respectively;

[0058] The two connecting pieces 9 are connected to the connecting rod shaft 10 via hinges.

[0059] The present invention enables the metal bipolar plate 6 to be clamped quickly by setting a flipping linkage mechanism, which effectively improves the welding efficiency. It can realize the flipping of the upper pressure plate 3 relative to the lower support plate 1, which facilitates the replacement of the metal bipolar plate 6 without disassembly.

[0060] To eliminate the problem of incorrect locking when flipping, the hinge of this invention adopts a hinge that can rotate 180 degrees. This structural design achieves anti-reverse and eliminates the problem of incorrect locking of the upper pressure plate 3 and the lower support plate 1 in the flipping direction. The upper pressure plate 3 and the lower support plate 1 can be flipped and welded on both sides, which greatly improves the welding efficiency.

[0061] As an optional embodiment of the present invention, in order to achieve locking in the compressed state, a locking assembly is provided. Furthermore, to simplify the structure and facilitate operation, this embodiment employs a locking assembly with the following structure: Figure 6 As shown, specifically, the locking assembly includes a fixing block 11, a pressure block 12, a locking pin 13, and a locking nut 14; wherein:

[0062] There are two pressure blocks 12, which are respectively set at the top and bottom of the fixed block 11. This structure creates a pressure space between the two pressure blocks 12, so that the lower support plate 1, the upper pressure plate 3 and the two metal electrode plates can be accommodated and pressed inside.

[0063] Through holes are provided on the pressure block 12, the upper pressure plate 3 and the lower support plate 1;

[0064] After the locking pin 13 passes through the through hole, both ends are screwed to the locking nut 14.

[0065] The two metal bipolar plates 6 are pressed flat and locked by the upper pressure plate 3 and the locking assembly, so that the two metal bipolar plates 6 are tightly attached, effectively ensuring the welding flatness of the metal bipolar plates 6.

[0066] In order to ensure smooth welding after the upper pressure plate 3 presses down the metal bipolar plate 6, in this embodiment, a through welding path groove is provided on the upper pressure plate 3 along the welding route. By opening a laser welding groove on the upper pressure plate 3 to optimize the laser welding path, the complex welding problem of the metal bipolar plate 6 is solved, and the laser welding process is effectively simplified.

[0067] Furthermore, since the metal bipolar plate 6 has its own flow channel structure, and in order to prevent the flow channel from being damaged during welding, in this embodiment, the welding path groove includes a straight path groove 4 and a serpentine path groove 5 with an S-shaped curve. The serpentine path groove 5 is provided to avoid the flow channel.

[0068] As an optional embodiment of the present invention, a plurality of welding grooves are provided on the metal bipolar plate 6 corresponding to the welding path groove positions. By providing welding grooves on the metal bipolar plate 6, the mechanical strength of the bipolar plate is guaranteed while effectively solving the problem of weak welding of the bipolar plate. Furthermore, the welding path grooves provided on the upper pressure plate 3 match the welding grooves on the metal bipolar plate 6. The laser can achieve rapid integrated welding through the welding path, which greatly increases the welding efficiency.

[0069] Specifically, the welding groove is opened along the edge contour of the metal bipolar plate 6, and the welding groove includes a straight welding groove 8 and a serpentine welding groove, while the straight welding groove 8 has a stepped groove structure.

[0070] This invention solves the problem of weak welding during bipolar plate welding by setting welding grooves at the edge of the metal bipolar plate 6, effectively increasing the flatness of the bipolar plate and ensuring the mechanical strength and flow channel integrity of the bipolar plate, thereby improving the welding quality of the metal bipolar plate 6.

[0071] It should be noted that when creating welding grooves on the metal bipolar plate 6, the following points need attention: Since there is a relationship between laser welding power and welding depth, width, and welding material, high power density and high absorptivity materials typically result in greater welding depths. Therefore, the groove depth is calculated based on the bipolar plate material and the laser power / welding depth, using the following formula:

[0072] Groove depth (h / mm) = Material thickness (h / mm) - Laser welding depth (h / mm).

[0073] The groove width is derived from the relationship between the laser beam focusing area and the sealing area of ​​the metal bipolar plate 6. Generally, the groove width should be greater than the width of the laser beam focusing area (i.e., the weld width) and less than the width of the bipolar plate sealing area. Through research and experimentation, this invention has found that a groove width of 1mm yields the best welding effect.

[0074] The serpentine welding groove is designed based on the surface flow channel structure of the metal bipolar plate 6 in the fuel cell. The serpentine welding groove effectively avoids the flow channel position, preventing the flow channel from being damaged by the laser beam. While ensuring the integrity of the flow channel of the metal bipolar plate 6, it solves the problem of weak welding due to edge warping of the metal bipolar plate 6.

[0075] In the prior art, the welding groove structure is mostly a single long straight groove. The serpentine welding groove of the present invention is developed and designed based on the bipolar plate flow channel structure. While ensuring the integrity of the flow channel, it also makes the bipolar plate welding more firm and prevents warping.

[0076] During the welding process, the laser beam welds the two metal bipolar plates 6 through the welding path groove on the upper pressure plate 3. After welding, the upper pressure plate 3 can be opened and closed through the flipping linkage mechanism, allowing the metal bipolar plates 6 to be replaced without removing the upper pressure plate 3. This greatly improves the welding efficiency of the bipolar plates. Furthermore, by opening welding grooves on the metal bipolar plates 6 and matching the welding path grooves on the tooling with the welding grooves on the metal plates, the welding efficiency is greatly improved. This ensures that the welding grooves on the bipolar plates cooperate with the welding tooling, while guaranteeing the mechanical strength and flow channel integrity of the bipolar plates. It also solves the problems of weak bipolar plate welding and plate warping, greatly improving the sealing performance and welding quality of the bipolar plates.

[0077] The present invention provides a welding apparatus, including a welding platform and a laser welding fixture for a fuel cell metal bipolar plate placed on the welding platform.

[0078] To further improve the clamping effect, the welding platform is a magnetizable platform with adjustable magnetic attraction; the upper pressure plate 3 is made of magnetically conductive material.

[0079] Furthermore, the lower support plate 1 can also be made of a magnetically conductive material.

[0080] The welding apparatus of this invention effectively solves the problem of warping during bipolar plate welding by setting up a lower support plate 1, an upper pressure plate 3, and a locking assembly. Simultaneously, the fixture is equipped with a flipping linkage mechanism, enabling rapid clamping of the metal bipolar plate 6, and the lower support plate 1 has a positioning boss 2 for accurate positioning of the bipolar plate, effectively improving the welding efficiency and quality of the metal bipolar plate 6. The welding fixture of this invention has a laser path groove on the upper pressure plate 3, enabling rapid welding and offering higher clamping and welding efficiency compared to other conventional fixtures. Furthermore, the welding groove on the bipolar plate solves the problem of weak welding of thick plates and ensures the mechanical strength of the metal bipolar plate 6. Additionally, by adding welding channels to the metal bipolar plate 6, symmetrical serpentine welding grooves on the bipolar plate effectively ensure the tightness of the bipolar plate welding, effectively avoiding stress concentration during welding, thus making the bipolar plate channels fit more tightly, greatly improving the performance of the bipolar plate and the welding quality.

[0081] In use, the lower support plate 1 and the upper pressure plate 3 are connected by a flipping linkage mechanism, and the upper pressure plate 3 can be opened and closed by the flipping linkage mechanism. During welding, the metal bipolar plate 6 is positioned between the lower support plate 1 and the upper pressure plate 3 and can be locked by the locking assembly.

[0082] The welding fixture of the present invention uses the pressing action of the lower support plate 1, the upper pressure plate 3 and the locking assembly to press and fix the metal bipolar plate 6. At the same time, the magnetic welding platform increases the pressure of the upper pressure plate 3 to ensure the tight fit and flatness of the two metal bipolar plates 6. This eliminates the problem of commonly used fixtures not pressing tightly and the bipolar plates being prone to misalignment, effectively avoids warping of the bipolar plates during welding, and greatly improves the welding quality of the metal bipolar plates 6.

[0083] In this embodiment, the welding platform is a magnetizable platform with adjustable magnetic attraction. The upper pressure plate 3 is made of magnetically conductive material to ensure the pressing effect on the bipolar plates. Since the upper pressure plate 3 is made of magnetically conductive material, when the welding platform generates magnetic force, it can interact with the upper pressure plate 3 to form a magnetic attraction force, thereby using the magnetic attraction force to press the two metal bipolar plates 6 together.

[0084] The welding platform can adjust the magnetic attraction force, allowing for the selection of a suitable magnetic attraction force to achieve a tight clamping fit between the two metal bipolar plates 6. Simultaneously, the lower support plate 1 can also be made of magnetized material, enabling the two metal bipolar plates 6 to adhere more firmly and smoothly to the welding platform. This interaction with the upper pressure plate 3 generates a greater attraction force, further improving the welding quality.

[0085] Because the pressed metal bipolar plate 6 is not perfectly flat, there are uneven areas. Furthermore, without proper positioning, the magnetic attraction can easily cause misalignment during welding. During laser welding, gaps may exist between the two metal bipolar plates 6, leading to a decrease in the bipolar plate's sealing performance.

[0086] To address this issue, preferably, a locking assembly is used to lock the lower support plate 1 and the upper pressure plate 3 together, thereby compensating for local unevenness on the surfaces of the two metal bipolar plates 6. This ensures a tight fit between the two metal bipolar plates 6 being welded, guaranteeing a firm and secure fit and effectively ensuring welding quality. Simultaneously, the lower support plate 1 is equipped with a positioning boss 2, which allows for rapid positioning of the bipolar plates during welding, ensuring alignment of the welding positions. This also improves the sealing performance of the bipolar plates during welding.

[0087] The metal bipolar plate 6 and the upper pressure plate 3 are positioned by the positioning boss 2 on the lower support plate 1, which can accurately position the two metal bipolar plates 6, so that the parts that need to be welded on the metal bipolar plates 6 are aligned, and the welding accuracy of the bipolar plates is guaranteed.

[0088] A laser welding path groove is provided on the upper pressure plate 3, corresponding to the welding position of the metal bipolar plate 6. During laser welding, the laser moves along the path groove, which can ensure the welding quality of the metal bipolar plate 6 at the welding position and improve the laser energy utilization efficiency.

[0089] For easy disassembly, the lower support plate 1 and the upper pressure plate 3 are connected by a flipping linkage mechanism, allowing relative movement between them. Upon completion of welding, simply open the upper pressure plate 3 via the flipping linkage mechanism to remove the welded metal bipolar plate 6, then place the new metal bipolar plate 6 on top. This significantly improves tooling changeover and welding efficiency. Furthermore, the flipping linkage mechanism incorporates anti-reverse measures, eliminating the problem of the upper pressure plate 3 and lower support plate 1 locking in the wrong flipping direction. The upper pressure plate 3 and lower support plate 1 can be flipped for welding on both sides, further enhancing welding efficiency.

[0090] The bipolar plates welded using this tooling are tightly connected, with no gas leakage.

[0091] In this embodiment, the thickness of the metal bipolar plate 6 is 2.5 mm, and the metal bipolar plate 6 is a stainless steel bipolar plate.

[0092] The welding method of the stainless steel bipolar plate 6 of the present invention is as follows: First, the stainless steel bipolar plate 6 is processed, specifically by CNC machining, then cleaned and dried; then, after the dried stainless steel bipolar plate 6 is properly fitted with the welding fixture, the two bipolar plates 6 are aligned and fixed by the positioning boss 2 on the lower support plate 1, and placed on the laser welding platform. At the same time, the welding platform is magnetized to more firmly fix the bipolar plates. During welding, 99.99% high-purity nitrogen gas is used to protect the weld (the gas output head of the high-purity nitrogen gas moves coaxially with the welding head of the quasi-continuous laser, blowing high-purity nitrogen gas onto the welding surface of the stainless steel bipolar plate to protect the weld). Then, the continuous laser emitted by the quasi-continuous laser directly welds the stainless steel bipolar plate. The working mode of the quasi-continuous laser is set to continuous mode, the average power of the continuous mode is 250W, the welding power is 250W, and the acceleration is 1000mm / s². 2 The speed was 25 mm / s, the laser wavelength was 1070 nm, and the protective gas flow rate was 20 L / min. The welded stainless steel bipolar plates met the requirements for bipolar plate weld seams, that is, the bipolar plate weld seams were tightly connected and there was no gas leakage.

[0093] Specifically, the processing of the stainless steel bipolar plate 6 includes: machining a welding groove on the edge contour of the stainless steel bipolar plate 6 (there is a certain relationship between laser welding power, welding depth, and welding material; therefore, the groove depth is calculated based on the bipolar plate material, laser power, and welding depth). The metal plate part is designed with a material thickness of 2.5mm. According to the formula: groove depth (h / mm) = material thickness (h / mm) - laser welding depth (h / mm), the optimal groove depth can be obtained. Simultaneously, based on the relationship between laser beam focusing and the bipolar plate sealing area, the groove width is determined: this invention found that a groove width of 1mm yields the best welding effect. Therefore, a wide groove of 4mm wide and 1mm deep is provided on the stainless steel bipolar plate 6 (e.g., ...). Figure 4 As shown), then narrow grooves (1mm wide and 1mm deep; 1mm wide and 0.8mm deep; 1mm wide and 0.7mm deep; 1mm wide and 0.6mm deep) were respectively opened in the center of the wide groove (as shown). Figure 4 (As shown), and then weld at the narrow groove. It should be noted that the above four narrow grooves correspond to four different embodiments, that is, in each embodiment, only one specification of narrow groove is provided.

[0094] Meanwhile, to ensure a stronger weld and eliminate stress concentration in the metal bipolar plate 6, laser-cut serpentine welding grooves are created in the flow channel region of the metal bipolar plate 6. These grooves, 1mm wide and 1mm deep, are symmetrically placed on both sides of the metal bipolar plate 6 (the serpentine shape is to avoid the flow channel structure and ensure its integrity). Welding in the flow channel region effectively increases the mechanical strength and sealing of the metal bipolar plate 6, significantly improving the welding quality and plate performance.

[0095] Example 1

[0096] (1) Polish the surface of the stainless steel bipolar plate (400×250×2.5mm) with sandpaper, clean it, and then dry it for later use.

[0097] (2) Place the dried stainless steel bipolar plate into a CNC machine tool, import the prepared machining program into the machine tool, and perform machining of the welding groove and positioning hole 7 (the bipolar plate is machined with a wide groove of 4mm wide and 1mm deep (e.g.) Figure 7 As shown), a narrow groove 1mm wide and 1mm deep is set in the center of the wide groove (as shown). Figure 7 (As shown).

[0098] (3) After the dried stainless steel bipolar plate 6 is properly assembled, it is placed on the laser welding fixture. The two bipolar plates are aligned and fixed by the positioning boss 2 of the lower support plate 1. Then, the welding fixture and the metal bipolar plate 6 are placed on the welding platform at the same time. The welding platform is magnetized to achieve a more secure fixation of the bipolar plate.

[0099] (4) Then, 99.99% high-purity nitrogen gas is used to protect the weld (the gas output head of the high-purity nitrogen gas moves coaxially with the welding head of the quasi-continuous laser, blowing high-purity nitrogen gas onto the welding surface of the stainless steel bipolar plate to protect the weld). Then, the continuous laser emitted by the quasi-continuous laser directly welds the stainless steel bipolar plate. The working mode of the quasi-continuous laser is set to continuous mode, the average power of the continuous mode is 250W, the welding power is 250W, and the acceleration is 1000mm / s. 2 The laser speed is 25 mm / s, the laser wavelength is 1070 nm, the shielding gas flow rate is 20 L / min, and then welding is performed.

[0100] Example 2

[0101] (1) Polish the surface of the stainless steel bipolar plate (400×250×2.5mm) with sandpaper, clean it, and then dry it for later use.

[0102] (2) Place the dried stainless steel bipolar plate into a CNC machine tool, import the prepared machining program into the machine tool, and perform machining of the welding groove and positioning hole 7 (the bipolar plate is machined with a wide groove of 4mm wide and 1mm deep (e.g.) Figure 8 As shown), a narrow groove with a width of 1mm and a depth of 0.8mm is set in the center of the wide groove (as shown). Figure 8 (As shown).

[0103] (3) After the dried stainless steel bipolar plate 6 is properly assembled, it is placed on the laser welding fixture. The two bipolar plates are aligned and fixed by the positioning boss 2 of the lower support plate 1. Then, the welding fixture and the metal bipolar plate 6 are placed on the welding platform at the same time. The welding platform is magnetized to achieve a more secure fixation of the bipolar plate.

[0104] (4) Then, 99.99% high-purity nitrogen gas is used to protect the weld (the gas output head of the high-purity nitrogen gas moves coaxially with the welding head of the quasi-continuous laser, blowing high-purity nitrogen gas onto the welding surface of the stainless steel bipolar plate to protect the weld). Then, the continuous laser emitted by the quasi-continuous laser directly welds the stainless steel bipolar plate. The working mode of the quasi-continuous laser is set to continuous mode, the average power of the continuous mode is 250W, the welding power is 250W, and the acceleration is 1000mm / s. 2 The laser speed is 25 mm / s, the laser wavelength is 1070 nm, the shielding gas flow rate is 20 L / min, and then welding is performed.

[0105] Example 3

[0106] (1) Polish the surface of the stainless steel bipolar plate (400×250×2.5mm) with sandpaper, clean it, and then dry it for later use.

[0107] (2) Place the dried stainless steel bipolar plate into a CNC machine tool, import the prepared machining program into the machine tool, and perform machining of the welding groove and positioning hole 7 (the bipolar plate is machined with a wide groove of 4mm wide and 1mm deep (e.g.) Figure 9 As shown), a narrow groove 1mm wide and 0.7mm deep is set in the center of the wide groove (as shown). Figure 9 (As shown).

[0108] (3) After the dried stainless steel bipolar plate 6 is properly assembled, it is placed on the laser welding fixture. The two bipolar plates are aligned and fixed by the positioning boss 2 of the lower support plate 1. Then, the welding fixture and the metal bipolar plate 6 are placed on the welding platform at the same time. The welding platform is magnetized to achieve a more secure fixation of the bipolar plate.

[0109] (4) Then, 99.99% high-purity nitrogen gas is used to protect the weld (the gas output head of the high-purity nitrogen gas moves coaxially with the welding head of the quasi-continuous laser, blowing high-purity nitrogen gas onto the welding surface of the stainless steel bipolar plate to protect the weld). Then, the continuous laser emitted by the quasi-continuous laser directly welds the stainless steel bipolar plate. The working mode of the quasi-continuous laser is set to continuous mode, the average power of the continuous mode is 250W, the welding power is 250W, and the acceleration is 1000mm / s. 2 The speed is 25mm / s, the laser wavelength is 1070nm, the shielding gas flow rate is 20L / min, and then welding is performed;

[0110] Example 4

[0111] (1) Polish the surface of the stainless steel bipolar plate (400×250×2.5mm) with sandpaper, clean it, and then dry it for later use.

[0112] (2) Place the dried stainless steel bipolar plate into a CNC machine tool, import the prepared machining program into the machine tool, and perform machining of the welding groove and positioning hole 7 (the bipolar plate is machined with a wide groove of 4mm wide and 1mm deep (e.g.) Figure 10 As shown), a narrow groove 1mm wide and 0.6mm deep is set in the center of the wide groove (as shown). Figure 10 (As shown).

[0113] (3) After the dried stainless steel bipolar plate 6 is properly assembled, it is placed on the laser welding fixture. The two bipolar plates are aligned and fixed by the positioning boss 2 of the lower support plate 1. Then, the welding fixture and the metal bipolar plate 6 are placed on the welding platform at the same time. The welding platform is magnetized to achieve a more secure fixation of the bipolar plate.

[0114] (4) Then, 99.99% high-purity nitrogen gas is used to protect the weld (the gas output head of the high-purity nitrogen gas moves coaxially with the welding head of the quasi-continuous laser, blowing high-purity nitrogen gas onto the welding surface of the stainless steel bipolar plate to protect the weld). Then, the continuous laser emitted by the quasi-continuous laser directly welds the stainless steel bipolar plate. The working mode of the quasi-continuous laser is set to continuous mode, the average power of the continuous mode is 250W, the welding power is 250W, and the acceleration is 1000mm / s. 2 The laser speed is 25 mm / s, the laser wavelength is 1070 nm, the shielding gas flow rate is 20 L / min, and then welding is performed.

[0115] Comparative Example 1

[0116] (1) Polish the surface of the stainless steel bipolar plate (400×250×2.5mm) with sandpaper, clean it, and then dry it for later use.

[0117] (2) Place the dried stainless steel bipolar plate into the CNC machine tool, import the prepared machining program into the machine tool, and do not perform welding groove treatment on the metal bipolar plate 6.

[0118] (3) After the dried stainless steel bipolar plate 6 is properly assembled, it is placed on the laser welding fixture. The two bipolar plates are aligned and fixed by the positioning boss 2 of the lower support plate 1. Then, the welding fixture and the metal bipolar plate 6 are placed on the welding platform at the same time. The welding platform is magnetized to achieve a more secure fixation of the bipolar plate.

[0119] (4) Then, 99.99% high-purity nitrogen gas is used to protect the weld (the gas output head of the high-purity nitrogen gas moves coaxially with the welding head of the quasi-continuous laser, blowing high-purity nitrogen gas onto the welding surface of the stainless steel bipolar plate to protect the weld). Then, the continuous laser emitted by the quasi-continuous laser directly welds the stainless steel bipolar plate. The working mode of the quasi-continuous laser is set to continuous mode, the average power of the continuous mode is 250W, the welding power is 250W, and the acceleration is 1000mm / s. 2 The speed is 25mm / s, the laser wavelength is 1070nm, the shielding gas flow rate is 20L / min, and then welding is performed;

[0120] The welding effect of the welded bipolar plate obtained in Comparative Example 1 was compared with that of the welded bipolar plates obtained in Examples 1, 2, 3, and 4. Figure 11 The image shows the welding effect of a slotted bipolar plate: After slotting and welding, the laser passes through the welding groove. As observed in the image, the weld spots are uniform and dense, and the two bipolar plates are tightly bonded without gaps. Slotted welding of bipolar plates effectively solves the problem of weak bipolar plate welding while ensuring the mechanical strength of the metal bipolar plate, thus improving the welding quality. Figure 12The image shows the welding effect of an ungrooved bipolar plate: As can be seen from the image, the laser welding weld spot is wide and discontinuous, and there is a noticeable crack after welding the two metal bipolar plates. Ungrooved bipolar plate welding fails to meet the sealing requirements, resulting in poor welding quality. The results show that Examples 1, 2, 3, and 4 are significantly better than Comparative Example 1 (e.g., ...). Figure 12 As shown), in Examples 1, 2, 3, and 4, the bipolar plates are welded tightly, and the welding effect is better than that of Comparative Example 1. Furthermore, in the four examples, Example 1 (as shown) exhibits superior welding performance. Figure 11 The welding effect shown is optimal.

[0121] First, it should be noted that "inward" refers to the direction towards the center of the storage space, while "outward" refers to the direction away from the center of the storage space.

[0122] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the appendix. Figure 1 The orientations or positional relationships shown are for the purpose of facilitating and simplifying the description of the present invention, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as limiting the present invention.

[0123] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0124] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0125] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0126] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0127] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A laser welding fixture for metal bipolar plates of fuel cells, characterized in that, Includes an upper pressure plate, a lower support plate, a flipping linkage mechanism, and a locking assembly, wherein: The lower support plate is used to support two metal bipolar plates to be welded; The upper pressure plate is rotatably mounted on the lower support plate via the flipping linkage mechanism, which can press the two metal bipolar plates together. The locking assembly is disposed between the lower support plate and the upper pressure plate, and has a locked state and a released state. When it is in the locked state, it can lock the position of the upper pressure plate and the lower support plate. When it is in the released state, it can release the upper pressure plate from the locked position. The upper pressure plate has through welding path grooves along the welding route, including straight path grooves and serpentine path grooves with S-shaped curves. The metal bipolar plate has a plurality of welding grooves corresponding to the welding path groove positions, the welding grooves including straight welding grooves and serpentine welding grooves; The straight welding groove is a stepped groove structure.

2. The laser welding fixture for fuel cell metal bipolar plates according to claim 1, characterized in that, The metal bipolar plate has positioning holes around its perimeter; the lower support plate has positioning bosses around its perimeter; the positioning bosses are engaged with the positioning holes to achieve positioning between the metal bipolar plate and the lower support plate.

3. The laser welding fixture for fuel cell metal bipolar plates according to claim 1, characterized in that, The flipping linkage mechanism includes a connecting piece, a connecting shaft, and a hinge; wherein: The number of connecting pieces is two, which are respectively connected to the upper pressure plate and the lower support plate; The two connecting pieces are respectively connected to the connecting rod shaft via hinges.

4. The laser welding fixture for fuel cell metal bipolar plates according to claim 3, characterized in that, The hinge is a 180-degree rotating hinge.

5. The laser welding fixture for fuel cell metal bipolar plates according to claim 1, characterized in that, The locking assembly includes a fixing block, a pressure block, a locking pin, and a locking nut; wherein: The number of pressure blocks is two, which are respectively set at the top and bottom of the fixed block; The pressure block, the upper pressure plate, and the lower support plate are provided with through holes; After passing through the through hole, the locking pin is screwed to the locking nut at both ends.

6. A welding apparatus, characterized in that, The invention includes a welding platform and a laser welding fixture for fuel cell metal bipolar plates as described in any one of claims 1-5, placed on the welding platform; the welding platform is a magnetizable platform with adjustable magnetic attraction; the upper pressure plate is made of a magnetically conductive material.

7. The welding apparatus according to claim 6, characterized in that, The lower support plate is made of magnetically conductive material.

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