A metal bipolar plate forming apparatus and method

Abstract

The application provides a metal bipolar plate forming device and method, which solves the technical problem that material is subjected to severe plastic deformation in a die forming process of an existing metal bipolar plate, which is easy to cause local rupture; the forming device is provided with a force transmission mechanism, the force transmission mechanism is provided with a force transmission plate, a force transmission rod and a pressure plate, the force transmission plate is arranged between an upper die bottom plate and an upper die plate; the upper die bottom plate is connected with the force transmission plate through a hydraulic spring; a top rod is connected to the upper surface of the force transmission plate, the upper end of the top rod penetrates through the force transmission plate and extends out, the force transmission plate is slidably connected with the top rod; one end of the force transmission rod is connected with the force transmission plate, the other end of the force transmission rod penetrates through a second through hole of the upper die plate downward and extends out and is connected with the pressure plate, the upper die plate is slidably connected with the force transmission rod, and the pressure plate is arranged above a lower die plate; and the device can be widely applied to the technical field of metal bipolar plates.

Description

Technical Field

[0001] This application relates to the field of metal bipolar plate technology, and in particular to a metal bipolar plate forming apparatus and method. Background Technology

[0002] Fuel cells, as efficient and clean energy conversion devices, have broad application prospects in transportation, distributed energy, and portable devices. Metal bipolar plates are one of the core components of fuel cells, primarily responsible for supporting the distribution of fuel and oxidant, conducting current, and providing mechanical support. Compared to traditional graphite bipolar plates, metal bipolar plates offer higher mechanical strength, electrical conductivity, and thermal conductivity, while allowing for significant reduction in thickness, thereby increasing the cell's power density.

[0003] Metal bipolar plates require complex flow field structures to achieve efficient gas distribution and water management. For example... Figure 1 As shown, a single microchannel of the bipolar plate is divided into five regions: the flange region, the upper rounded corner region, the sidewall region, the lower rounded corner region, and the bottom region. The connection between the upper rounded corner region and the lower rounded corner region is designated as region A, and the connection between the lower rounded corner region and the sidewall region is designated as region B.

[0004] In common molding processes, the thickness distribution of the microchannels in bipolar plates is noticeably uneven at the cross-sectional surface; for example... Figure 2 As shown, the thickness reduction rate of regions A and B in bipolar microchannels typically reaches 20%-30%; the sidewall region also undergoes significant deformation, with a thickness reduction rate in the range of 15%-20%; the flange region and bottom region only experience very small deformation, with a thickness reduction rate of around 5%. Therefore, regions A and B of the bipolar microchannel are the main deformation areas, with severe thickness reduction. Severe thickness reduction means that the material undergoes intense plastic deformation during the forming process, which can easily lead to localized cracking, especially in regions A and B of the bipolar microchannel. This reduces the service life and mechanical support stiffness of the metal bipolar plate. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of the aforementioned technologies by providing a metal bipolar plate forming apparatus and method that improves the uniformity of the thickness of the entire microchannel of the metal bipolar plate and prevents breakage.

[0006] To this end, the application provides a metal bipolar plate forming device, which is provided with an upper die mechanism and a lower die mechanism, the upper die mechanism is provided with an upper die base plate and an upper die plate, the lower surface of the upper die plate is provided with micro protrusions, the lower die mechanism is provided with a lower die base plate and a lower die plate, the upper surface of the lower die base plate is provided with micro grooves, the upper die plate and the lower die plate are arranged oppositely, the micro protrusions and the micro grooves are matched to form micro flow channels after the upper die plate and the lower die plate are closed, the forming device is further provided with a force transmission mechanism, the force transmission mechanism is provided with a force transmission plate, a force transmission rod and a pressure plate, the force transmission plate is provided with an ultrasonic vibration device, the force transmission plate is arranged between the upper die base plate and the upper die plate, the upper die base plate and the force transmission plate are connected through a hydraulic spring, the upper surface of the force transmission plate is connected with a top rod, the upper end of the top rod penetrates through the force transmission plate and extends out, the force transmission plate and the top rod are connected in sliding mode, one end of the force transmission rod is connected with the force transmission plate, the other end of the force transmission rod penetrates through a second through hole of the upper die plate downward and extends out and is connected with the pressure plate, the upper die plate and the force transmission rod are connected in sliding mode, and the pressure plate is arranged above the lower die plate.

[0007] Preferably, the pressure plate is provided with a first through hole for the micro protrusions to penetrate through when the upper die plate and the lower die plate are closed.

[0008] Preferably, the ultrasonic vibration device is provided with a vibration rod and an amplitude rod which are connected with each other, and the vibration rod is connected with the force transmission plate.

[0009] Preferably, the forming device is further provided with a first guide column, the two ends of the first guide column are connected with the upper die base plate and the lower die base plate respectively, and the first guide column penetrates through the upper die base plate, the force transmission plate, the upper die plate and the lower die plate in sliding mode respectively.

[0010] Preferably, the second through hole of the upper die plate is a square hole, the other end of the force transmission rod penetrates through the square hole downward and extends out and is connected with the pressure plate.

[0011] Preferably, the forming device is further provided with a supporting device, the supporting device is provided with a second guide column, a guide sleeve and a spring, the spring is installed in the guide sleeve, the upper end of the second guide column is connected with the upper die plate, the lower end of the second guide column is inserted into the guide sleeve and connected with the spring, and the bottom of the guide sleeve is connected with the lower die plate.

[0012] The application further provides a metal bipolar plate forming method, which uses the metal bipolar plate forming device as described in any one of the above.

[0013] The beneficial effects of the application are: the application provides a metal bipolar plate forming device and method, the upper die base plate moves downward, driving the hydraulic spring, the force transmission plate, the force transmission rod and the edge pad to move downward until contacting the surface of the plate workpiece. After the edge pad contacts the plate workpiece, the upper die base plate continues to move downward, compressing the hydraulic spring, and the hydraulic spring transmits pressure to the force transmission plate, the force transmission rod, the edge pad, and finally to the plate workpiece. During the micro-channel forming process, the material in the flange area yields under the action of normal stress and tensile stress, and the material flows, thereby reducing the thickness reduction of the upper fillet, the sidewall and the lower fillet area, thereby improving the uniformity of the entire micro-channel thickness of the metal bipolar plate, avoiding the occurrence of cracking, optimizing the metal bipolar plate forming process, and having important significance for promoting the industrialization development of fuel cells. BRIEF DESCRIPTION OF DRAWINGS

[0014] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the embodiments or prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0015] Figure 1 The structure diagram of the thickness reduction rate of different regions of the micro-channel in the bipolar plate is shown in the figure.

[0016] Figure 2 The structure diagram of the thickness reduction rate of different regions of the micro-channel in the bipolar plate is shown in the figure.

[0017] Figure 3 The structure diagram of the metal bipolar plate forming device of the present application is shown in the figure.

[0018] Figure 4 The structure diagram of the top view of the upper die plate of the present application is shown in the figure.

[0019] Figure 5 The structure diagram of the perspective view of the upper die plate of the present application is shown in the figure.

[0020] Figure 6 The structure diagram of the edge pad of the present application is shown in the figure.

[0021] Figure 7 The structure diagram of the A part shown in the enlarged view is shown in the figure. Figure 3 The structure diagram of the A part shown in the enlarged view is shown in the figure.

[0022] Marked in the figure: 1. upper die base plate, 2. first guide column, 3. force transmission plate, 4. upper die plate, 5. lower die plate, 6. ultrasonic vibration device, 7. vibration rod, 8. amplitude rod, 9. ejector rod, 10. hydraulic spring, 11. force transmission rod, 12. blank holder, 13. first through hole, 16. lower die base plate, 17. micro convex, 18. micro concave, 19. plate workpiece, 20. support device, 21. second guide column, 22. guide sleeve, 23. spring, 24. second through hole. DETAILED DESCRIPTION

[0023] In order to make the technical problems, technical solutions and beneficial effects of the present application more clearly understood, the present application will be further described in detail below in conjunction with the drawings and examples. It should be understood that the specific examples described herein are only intended to explain the present application and not to limit the present application. The methods used in the invention are conventional methods unless otherwise specified; the raw materials and devices used are conventional commercially available products unless otherwise specified.

[0024] As shown in Figures 3-6 The present application provides a metal bipolar plate forming device, which is provided with an upper die mechanism and a lower die mechanism. The upper die mechanism is provided with an upper die base plate 1 and an upper die plate 4, and the lower surface of the upper die plate 4 is provided with a micro convex 17. The lower die mechanism is provided with a lower die base plate 16 and a lower die plate 5, and the upper surface of the lower base plate is provided with a micro concave 18. The upper die plate 4 and the lower die plate 5 are arranged oppositely, and the micro convex 17 and the micro concave 18 are matched to form a micro flow channel after the die is closed.

[0025] The forming device is also provided with a force transmission mechanism, which is provided with a force transmission plate 3, a force transmission rod 11 and a blank holder 12. The force transmission plate 3 is arranged between the upper die base plate 1 and the upper die plate 4, and the upper die base plate 1 and the force transmission plate 3 are connected by a hydraulic spring 10. The specification of the hydraulic spring 10 can be customized according to the actual situation. The upper surface of the force transmission plate 3 is connected with an ejector rod 9, the upper end of which penetrates through the force transmission plate 3 and extends out, and the force transmission plate 3 and the ejector rod 9 are slidingly connected. One end of the force transmission rod 11 is connected with the force transmission plate 3, and the other end of the force transmission rod 11 penetrates through the second through hole 24 of the upper die plate 4 downward and extends out to be connected with the blank holder 12. The upper die plate 4 and the force transmission rod 11 are slidingly connected, and the blank holder 12 is arranged above the lower die plate 5.

[0026] In use, the upper die base plate 1 and the lower die base plate 16 are fixed on the hydraulic machine respectively, wherein the upper die base plate 1 is fixedly connected with the crossbeam of the hydraulic machine, the lower die base plate 16 is fixed on the base of the hydraulic machine, and the pressing amount of the upper die base plate 1 is controlled by controlling the displacement of the crossbeam of the hydraulic machine; the plate workpiece 19 to be formed is placed in the forming area on the lower die plate 5. The specific forming process is that the upper die base plate 1 moves downward, driving the hydraulic spring 10, the force transmission plate 3, the force transmission rod 11 and the blank holder 12 to move downward until contacting the surface of the plate workpiece 19. After the blank holder 12 contacts the plate workpiece 19, the upper die base plate 1 continues to move downward, compressing the hydraulic spring 10, and the hydraulic spring 10 transmits the pressure to the force transmission plate 3, the force transmission rod 11, the blank holder 12 and finally to the plate workpiece 19. When the upper die base plate 1 continues to move downward, the upper surface of the upper die base plate 1 contacts the upper end of the ejector pin 9, and the ejector pin 9 and the upper die plate 4 move downward to complete the die closing. After the forming is completed, the upper die base plate 1 moves upward, driving the hydraulic spring 10, the force transmission plate 3, the force transmission rod 11 and the blank holder 12 to move upward, and the blank holder 12 drives the upper die plate 4 to move upward to realize the die opening.

[0027] The present application applies the blank holder 12 to exert the normal stress perpendicular to the plane on the flange area of the plate workpiece 19 before forming. According to the Mises yield criterion, the exertion of the normal stress σ3 (i.e. the force upward perpendicular to the plate plane of the plate workpiece 19) can reduce the yield stress σ1 and σ2 of the other two principal stress directions (i.e. the two mutually perpendicular principal stress directions in the plate plane of the plate workpiece 19). When a sufficient normal stress σ3 is exerted, in the micro-channel forming process, the material in the flange area yields under the action of the normal stress σ3 and the tensile stresses σ1 and σ2, the material flows, thereby reducing the thickness thinning of the upper fillet area, the side wall area and the lower fillet area, thereby improving the thickness uniformity of the entire micro-channel of the metal bipolar plate and avoiding the occurrence of cracking.

[0028] The present application adopts the hydraulic spring 10, and the operator can customize the parameters of the hydraulic spring 10 according to the actual situation, specifically the relationship between the compression amount and the pressure of the hydraulic spring 10, thereby controlling the pressure value provided by the hydraulic spring 10 in the pressing process of the upper die base plate 1, and the stable pressure can be provided during the compression of the hydraulic spring 10, thereby providing the stable normal stress of the blank holder 12 to the plate workpiece 19 in the deformation process.

[0029] In some embodiments, the hydraulic spring 10 is configured to provide a force to the blank holder 12, Figure 3 , Figure 5 , Figure 6As shown, the first through hole 13 is preferably provided on the blank holder plate 12 for the micro convex 17 to pass through during the clamping. The blank holder plate 12 is designed according to the micro channel shape, and the specific shape is consistent with the flange area of the bipolar plate. During the clamping, the micro convex 17 of the upper die plate 4 passes through the first through hole 13, and then the corresponding area of the plate workpiece 19 is pressed into the micro concave 18 of the lower die plate 5. Finally, the upper die plate 4 and the lower die plate 5 are clamped, and the micro channel of the bipolar plate is formed between them.

[0030] In some embodiments, the ultrasonic vibration device 6 is connected to the transmission plate 3. Figure 3 As shown, the transmission plate 3 is preferably provided with an ultrasonic vibration device 6. During the forming process, the ultrasonic vibration device 6 is always turned on to ensure that the vibration assembly always maintains high-frequency resonance to the transmission plate 3, thereby ensuring that the blank holder plate 12 and the plate workpiece 19 are always in a high-frequency resonance state during the pressure forming process of the plate workpiece 19.

[0031] In some embodiments, the ultrasonic vibration device 6 is connected to the transmission plate 3. Figure 3 As shown, the ultrasonic vibration device 6 belongs to the prior art, and is preferably provided with a vibration rod 7 and an amplitude rod 8 connected to each other, and the vibration rod 7 is connected to the transmission plate 3. The ultrasonic vibration device 6 is controlled by a transducer and an ultrasonic generator. When in use, the ultrasonic generator is started to make the ultrasonic wave pass through the transducer, the amplitude rod 8 and the vibration rod 7 to drive the transmission plate 3 to move at a high frequency.

[0032] In some embodiments, the ultrasonic vibration device 6 is connected to the transmission plate 3. Figure 3 As shown, the forming device is also preferably provided with a first guide column 2 for guiding and positioning. The two ends of the first guide column 2 are respectively connected to the upper die bottom plate 1 and the lower die bottom plate 16, and the first guide column 2 is respectively connected to the upper die bottom plate 1, the transmission plate 3, the upper die plate 4 and the lower die plate 5.

[0033] In some embodiments, the ultrasonic vibration device 6 is connected to the transmission plate 3. Figure 4 As shown, the second through hole 24 provided on the upper die plate 4 is preferably a square hole with good stability. The other end of the transmission rod 11 passes through the square hole downward and extends to be connected to the blank holder plate 12.

[0034] In some embodiments, the ultrasonic vibration device 6 is connected to the transmission plate 3. Figure 3 , Figure 7As shown, the forming device is also preferably provided with a support device 20, which is installed between the upper die plate 4 and the lower die plate 5. The support device 20 is provided with a second guide column 21, a guide sleeve 22, and a spring 23, which is installed in the guide sleeve 22. The upper end of the second guide column 21 is connected with the upper die plate 4, and the lower end of the second guide column 21 is inserted into the guide sleeve 22 and connected with the spring 23. The bottom of the guide sleeve 22 is connected with the lower die plate 5. When the forming device is closed, the part of the second guide column 21 is pressed downward into the guide sleeve 22 by the upper die plate 4, and the spring 23 is constantly compressed, and finally the closing of the die is completed. When the forming device is opened, the upper die plate 4 is pushed up by the second guide column 21 under the action of the spring 23, so that the upper die plate 4 and the lower die plate 5 are separated.

[0035] The application also provides a metal bipolar plate forming method using the metal bipolar plate forming device according to any one of the above.

[0036] It should be noted that:

[0037] (1) In the process of edge pressing, a large friction force exists between the edge pressing plate 12 and the flange area of the plate workpiece 19 due to a large pressing stress, which makes it difficult for the material in the flange area to flow. Therefore, the application requires that a suitable lubricant (preferably a fat) be evenly applied to the surface of the edge pressing plate 12 and the plate workpiece 19 before forming, and at the same time, the ultrasonic vibration device 6 is turned on to drive the force transmission plate 3, the force transmission rod 11 and the edge pressing plate 12 to vibrate at a high frequency, thereby effectively reducing the friction between the edge pressing plate 12 and the plate workpiece 19.

[0038] (2) The distance between the ejector rod 9 and the upper die bottom plate 1 can be designed according to the actual situation, so that the hydraulic spring 10 can provide a large enough normal pressure stress before the upper die bottom plate 1 contacts the upper end of the ejector rod 9 to push the upper die plate 4 to form, so that the material in the flange area of the bipolar plate can flow plastically during the forming process, i.e. when the upper die bottom plate 1 contacts the ejector rod 9 to push the upper die plate 4 to form, thereby improving the uniformity of the thickness of the micro flow channel after forming.

[0039] (3) The edge pressing plate 12 is used to apply a large normal pressure stress to the flange area of the upper die plate 4, which promotes the uniformity of stress during the deformation of the entire bipolar plate, and effectively reduces the springback of the bipolar plate after forming.

[0040] In the description of the application, it should be understood that the terms "left", "right", "up", "down", "top", "bottom", "front", "back", "inner", "outer", "back", "middle" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only used to facilitate the description of the application and simplify the description, and therefore cannot be understood as indicating or implying that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the application.

[0041] The above only describes preferred embodiments of the present application and is not used to limit the present application, and any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A metal bipolar plate forming apparatus, the forming apparatus comprising an upper mold mechanism and a lower mold mechanism, the upper mold mechanism comprising an upper mold base plate (1) and an upper template (4), the lower surface of the upper template (4) being provided with micro protrusions (17); the lower mold mechanism comprising a lower mold base plate (16) and a lower template (5), the upper surface of the lower template being provided with micro grooves (18), the upper template (4) and the lower template (5) being arranged vertically opposite each other, wherein after mold closing, the micro protrusions (17) and the micro grooves (18) match to form microchannels, characterized in that, The forming device is also provided with a force transmission mechanism, which is provided with a force transmission plate (3), a force transmission rod (11) and a pressure plate (12). The force transmission plate (3) is disposed between the upper mold base plate (1) and the upper template (4). The upper mold base plate (1) and the force transmission plate (3) are connected by a hydraulic spring (10). A top rod (9) is connected to the upper surface of the force transmission plate (3). The upper end of the top rod (9) passes through the force transmission plate (3) and extends out. The force transmission plate (3) and the top rod (9) are slidably connected. One end of the force transmission rod (11) is connected to the force transmission plate (3). The other end of the force transmission rod (11) passes downward through the second through hole (24) of the upper template (4) and extends out to be connected to the pressure plate (12). The upper template (4) and the force transmission rod (11) are slidably connected. The pressure plate (12) is positioned above the lower template (5). The pressure plate (12) has a first through hole (13) through which the micro protrusion (17) passes when the mold is closed. The pressure plate (12) is designed according to the shape of the microchannel, and its specific shape is consistent with the flange area of ​​the metal bipolar plate. It is used to apply a normal stress perpendicular to the plane to the flange area of ​​the sheet metal workpiece (19) before forming. The force transmission plate (3) is equipped with an ultrasonic vibration device (6); The forming device is also provided with a support device (20), which is provided with a second guide post (21), a guide sleeve (22), and a spring (23). The spring (23) is installed in the guide sleeve (22). The upper end of the second guide post (21) is connected to the upper template (4), and the lower end of the second guide post (21) is inserted into the guide sleeve (22) and connected to the spring (23). The bottom of the guide sleeve (22) is connected to the lower template (5).

2. The metal bipolar plate forming apparatus according to claim 1, characterized in that, The ultrasonic vibration device (6) is provided with a vibration rod (7) and an amplitude transformer (8) connected to each other. The vibration rod (7) is connected to the force transmission plate (3).

3. The metal bipolar plate forming apparatus according to claim 1, characterized in that, The forming device is also provided with a first guide post (2), the two ends of which are connected to the upper mold base plate (1) and the lower mold base plate (16) respectively. The first guide post (2) slides through the upper mold base plate (1), the force transmission plate (3), the upper template (4), and the lower template (5).

4. The metal bipolar plate forming apparatus according to claim 1, characterized in that, The second through hole (24) of the upper template (4) is a square hole, and the other end of the force transmission rod (11) passes through the square hole downward and extends out to connect with the pressure plate (12).

5. A method for forming a metal bipolar plate, characterized in that, Use the metal bipolar plate forming apparatus as described in any one of claims 1-4.

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