Fuel cell bipolar plate and processing method thereof

Abstract

The invention provides a fuel cell bipolar plate and a processing method thereof applied to the field of bipolar plates, the fuel cell bipolar plate comprises a bipolar plate, the bipolar plate is annular and is divided into a high-position sector and a low-position sector, two groups of connecting sectors are symmetrically arranged between the high-position sector and the low-position sector, the height of the section of the high-position sector is gradually reduced towards the circumferential side along the circle center, and the height of the section of the low-position sector is gradually reduced towards the circumferential side along the circle center. The height of the section of the low-position sector is gradually reduced from the circumferential side to the circle center, the height of the two sides of the high-position sector is higher than that of the two sides of the low-position sector, and the connecting sector smoothly connects the two sides of the high-position sector and the two sides of the low-position sector; the upper and lower sides of the high-position sector, the connecting sector and the low-position sector are respectively provided with a high-position water guide groove, a connecting water guide groove and a low-position water guide groove; the bipolar plate provided by the invention adopts an annular design, is divided into the high-position sectors, the low-position sectors and the connecting sectors, and is combined with the snake-shaped water chute, so that the discharge of water and the uniform distribution of gas are facilitated, the occurrence of a'water blockage 'phenomenon is reduced, and the reaction efficiency and the stability of the fuel cell are improved.

Description

Technical Field

[0001] The present application relates to the field of bipolar plates, and in particular to a fuel cell bipolar plate and a processing method thereof. Background Art

[0002] As the core component of a fuel cell, the bipolar plate performs important functions such as conducting current, distributing reactant gases, removing product water, and dissipating heat. Its performance directly impacts the fuel cell's power density, service life, and operational stability. Existing bipolar plates present numerous problems. Structurally, they are typically flat or simple channel-shaped, with poorly designed gas and water flow paths. This leads to uneven gas distribution, difficult water management, and the risk of water blockage, which impacts fuel cell efficiency.

[0003] In terms of materials and coatings, the bonding between the metal substrate and the coating is insufficient, leading to coating shedding over time, which in turn reduces the conductivity and corrosion resistance of the bipolar plates. In terms of processing, the precision and stability of the punching mechanism need to be improved, making it difficult to ensure the dimensional accuracy and consistency of the bipolar plates. Furthermore, the quality of the flow channel processing can also affect the flow properties of the fluid. In order to solve the above problems, the present invention proposes a novel fuel cell bipolar plate and a processing method thereof. Summary of the Invention

[0004] The present application aims to improve the performance and processing quality of bipolar plates to meet the requirements of efficient and stable operation of fuel cells. Compared with the prior art, a fuel cell bipolar plate and a processing method thereof are provided, including a bipolar plate, wherein the bipolar plate is annular and is divided into a high-position sector and a low-position sector according to a height difference. Two groups of connecting sectors are symmetrically provided between the high-position sector and the low-position sector. The cross-section of the high-position sector gradually decreases in height along the center toward the circumference, and the cross-section of the low-position sector gradually decreases in height along the circumference toward the center, and the heights of both sides of the high-position sector are higher than the heights of both sides of the low-position sector. The connecting sectors smoothly connect both sides of the high-position sector and the low-position sector. An input hole is provided at the highest point of the high-position sector, and an output hole is provided at the lowest point of the low-position sector. Two groups of symmetrically arranged high-position water guide grooves, connecting water guide grooves and low-position water guide grooves are respectively provided on the upper and lower sides of the high-position sector, the connecting sector and the low-position sector. The input end of the high-position water guide groove is connected to the input hole, the output end of the low-position water guide groove is connected to the output hole, the output end of the high-position water guide groove is connected to the input end of the low-position water guide groove through the connecting water guide groove. The high-position water guide groove and the low-position water guide groove are circumferentially circumferentially circulated, and the connecting water guide groove is radially circumferential ... The center of the bipolar plate is further provided with a positioning hole, and the plurality of bipolar plates are sleeved on the central shaft through the positioning hole. The central shaft is also provided with an input tube and an output tube matching the input hole and the output hole.

[0005] Furthermore, a connecting piece is fixed on the circumferential side of the bipolar plate, and the connecting piece includes a planar ring, and a plurality of snap grooves and snaps evenly distributed at equal angles are fixed on the upper and lower sides of the planar ring, and two sets of sealing gaskets are fixed on the upper and lower sides of the planar ring.

[0006] Furthermore, the bipolar plate includes a metal matrix layer from the inside out in order of material, a gradient transition layer is provided on both sides of the metal matrix layer, and a conductive coating is provided on the side of the gradient transition layer away from the metal matrix layer; The thickness of the metal matrix layer is 0.15 to 0.2 mm; The gradient transition layer has a Cr-CrN-CrCN gradient structure, where the Cr content gradually decreases from the side close to the metal base layer to the side away from it, while the N and C content gradually increases. Specifically, the total thickness of the gradient transition layer is 1.8-3.5 μm, wherein: the inner layer close to the metal base layer is mainly Cr, with a thickness of 1-2 μm and a Cr content of 80-90 at%; the middle layer is mainly CrN, with a thickness of 0.5-1 μm and a CrN phase ratio of 60% to 70%; the outer layer away from the metal base layer is mainly CrCN, with a thickness of 0.3-0.5 μm and a CrCN phase ratio of 50% to 60%; The conductive coating is a graphene / carbon nanotube composite film, and the surface layer of the conductive coating is embedded with nano-metal particles. The graphene sheets in the conductive coating have a diameter of 10-20 μm, the carbon nanotubes have a diameter of 5-10 nm, the mass ratio of the two is 3:1, and the composite film has a thickness of 1-2 μm. The nano-metal particles are platinum particles with a particle size of 2-5 nm and a loading of 0.1-0.3 mg / cm.

[0007] A method for processing a fuel cell bipolar plate comprises the following steps: S1. Using a punching mechanism, a metal base layer is punched out from a sheet material, and prefabricated connectors are welded. After annealing the metal base layer and the connectors, nano-etching is performed on the upper and lower sides of the metal base layer using an anodic oxidation method to form columnar pits with a diameter of 50-100 nm. S2. Using PECVD technology, by controlling the gas flow ratio of Ar, N2, and CH4, a gradient transition layer is deposited on the surface of the metal substrate layer. The vacuum degree of PECVD deposition is 1×10⁻³Pa, the power is 300-400W, and the gradient is achieved by the following methods: When depositing the inner layer, N2 / CH4=0, Ar flow rate 50sccm; When depositing the middle layer, N2 / CH4=10 / 1, Ar flow rate 40sccm; When depositing the outer layer, N2 / CH4=5 / 1, Ar flow rate 30sccm; S3. Electrophoretic deposition of a graphene / carbon nanotube composite film. After thermal reduction, pulse electrodeposition of metal nanoparticles was used to form a conductive coating on the surface of the gradient transition layer. The electrophoretic deposition parameters were as follows: graphene and carbon nanotubes were dispersed in an ethanol-water mixture at a volume ratio of 1:1, a voltage of 15 V, and a deposition time of 10 minutes; thermal reduction was performed by heating at 300°C in an N2 atmosphere for 1 hour; and pulse electrodeposition was performed using a 0.01 mol / L H2PtCl6 solution, a 50 Hz pulse current, a peak current density of 10 mA / cm², and a deposition time of 30 seconds. S4. Etch gas grooves on both sides of the high-level water guide groove, the connecting water guide groove and the low-level water guide groove by using a femtosecond laser to match the flow directions of the high-level water guide groove, the connecting water guide groove and the low-level water guide groove, and apply a superhydrophobic coating inside the high-level water guide groove, the connecting water guide groove and the low-level water guide groove, wherein the pulse width of the femtosecond laser is 100fs and the power is 50W.

[0008] Furthermore, the blanking mechanism includes a transmission mechanism that serves as a blanking base and transports the sheet material; A clamping mechanism provided on the transmission mechanism is used for punching the metal base layer from the sheet material and forming it by stamping; The adjustment mechanism provided on the mold clamping mechanism is used to control the height position of the plate conveyed by the transmission mechanism.

[0009] Furthermore, the mold clamping mechanism includes a lower mold base fixed on the transmission mechanism, a lower mold core is fixed on the top of the lower mold base, slide rods are symmetrically fixed on both sides of the top of the lower mold base, an upper mold base is provided on the top of the lower mold base, and sliding sleeves matching the slide rods are provided on both sides of the upper mold base, and a return spring is sleeved on the slide rod; An upper mold core is fixed to the bottom of the upper mold base, a pressure platform is slidably connected to the top of the upper mold base, the top of the pressure platform is connected to the output end of the hydraulic mechanism, and a tension spring 1 is fixed between the pressure platform and the upper mold base; A punching knife group and a trimming ring knife are fixed to the bottom of the pressure platform respectively. The inner diameter of the punching knife group is equal to the outer diameter of the upper mold core. The upper mold core is provided with an upper knife hole matching the punching knife group, and the lower mold core is provided with a lower knife hole corresponding to the punching knife group.

[0010] Furthermore, the transmission mechanism includes a base, the top of the base is slidably connected to a lifting seat in the vertical direction, two sets of plate conveyor belts are symmetrically arranged on the top of the lifting seat, four sets of height cylinders are fixed on the base, the output ends of the height cylinders are fixedly connected to the lifting seat, and the lifting seat is also fixed with two sets of symmetrically arranged side guide rollers on both sides of the mold clamping mechanism; The base is provided with a waste conveyor belt at the bottom of the lower mold core, and the lifting seat is also provided with a finished product conveyor belt between the plate conveyor belt and the waste conveyor belt.

[0011] Furthermore, the adjusting mechanism includes two groups of pneumatic cylinder bodies symmetrically fixed on the top of the upper mold base. A one-way valve is provided on the top of the pneumatic cylinder body for one-way air intake. The top of the sliding rod extends into the pneumatic cylinder body and is fixed with a piston. The pneumatic cylinder body is provided with an air guide interface on the bottom side of the piston, and the air guide interface is connected to the cylinder body of the height cylinder through a pipeline.

[0012] Furthermore, the top of the lower mold core is also provided with a plurality of obliquely arranged air-jet micro-holes; The top of the piston is rotatably connected with an adjusting ring, and two groups of symmetrically arranged limit blocks 2 are fixed on the circumferential side of the adjusting ring. A limit block 1 corresponding to the limit block 2 is provided in the piston, and a tensioning spring 2 is clamped between the limit block 2 and the limit block. An air flow channel is provided in the piston and the lower die base, and the output end of the air flow channel is connected to the input end of the air injection microhole and a valve mechanism is provided at the connection between the two. An eccentric air port corresponding to the input end of the air flow channel is provided on the adjusting ring; Two groups of rotationally symmetrical lower bevel plates are fixed on the top of the adjusting ring, a connecting rod is fixed on the inner top of the pneumatic cylinder body, and an upper bevel plate matching the lower bevel plates is provided on the bottom of the connecting rod.

[0013] Furthermore, when the tension spring 2 is in a free state, the eccentric air port and the input end of the air flow channel are staggered and closed; The valve mechanism includes a magnetic plunger slidably connected to the lower die base in the vertical direction, a return spring 2 is clamped between the top of the magnetic plunger and the lower die base, and an electromagnetic block that cooperates with the magnetic plunger is fixed in the upper die core.

[0014] Compared with the existing technology, the advantages of this application are: The bipolar plate of the present invention adopts a circular ring design and is divided into a high sector, a low sector and a connecting sector. Combined with a serpentine water guide groove, it is conducive to the discharge of water and the uniform distribution of gas, reducing the occurrence of "water blockage" phenomenon and improving the reaction efficiency and stability of the fuel cell. The processing method of the present invention adopts a blanking mechanism to realize rapid blanking and forming of the metal base layer, has a complete plate, waste and finished product conveying mechanism, has high processing efficiency, and adopts a combination of PECVD technology, electrophoretic deposition, pulse electrodeposition and other processes to improve the processing quality of the flow channel and the flow performance of the fluid. The entire processing process has a high degree of automation, ensuring the consistency and stability of the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a schematic diagram of the front structure of the bipolar plate proposed in this application; Figure 2 Schematic diagram of the bottom explosion structure of the bipolar plate proposed in this application; Figure 3 Schematic diagram of the cross-sectional structure of the bipolar plate proposed in this application; Figure 4 for Figure 3 A schematic diagram of the enlarged structure of the middle part A; Figure 5 This is a schematic diagram of the assembly state of the bipolar plate proposed in this application; Figure 6 A schematic diagram of the height fluctuation of the bipolar plate proposed in this application; Figure 7 A schematic diagram of the structure of the blanking mechanism and the plate proposed in this application; Figure 8 A schematic structural diagram of the blanking mechanism proposed in this application; Figure 9 A schematic diagram of the bottom structure of the upper mold core and its components proposed in this application; Figure 10 Schematic diagram of the bottom exploded structure of the upper mold core and its components proposed in this application; Figure 11 This is a schematic diagram of the exploded structure of the regulating mechanism proposed in this application; Figure 12 This is a schematic diagram of the structure of the piston and the adjusting ring proposed in this application; Figure 13 This is a schematic structural diagram of the lower mold core proposed in this application; Figure 14 A schematic diagram of the transverse cross-sectional structure of the blanking mechanism proposed in this application; Figure 15 for Figure 14 A schematic diagram of the enlarged structure of the middle part B; Figure 16 A schematic diagram of the longitudinal cross-sectional structure of the blanking mechanism proposed in this application; Figure 17 This is a schematic diagram comparing the downward movement of the pressure platform and the upper die seat proposed in this application.

[0016] Description of the numbers in the figure: 1. Bipolar plate; 101. Metal matrix layer; 102. Gradient transition layer; 103. Conductive coating; 11. High sector; 111. High water channel; 12. Connecting sector; 121. Connecting water channel; 13. Low sector; 131. Low water channel; 14. Input hole; 15. Positioning hole; 16. Output hole; 2. Connector; 21. Flat ring; 22. Sealing gasket; 23. Buckle groove; 24. Buckle; 3. Central shaft; 31. Input pipe; 32. Output pipe; 4. Conveying mechanism; 41. Base; 42. Plate conveyor belt; 421. Lifting seat; 422. Side guide rollers; 43. Height cylinder; 44. Waste conveyor belt; 45. Finished product conveyor belt; 5. Clamping mechanism; 51. Pressure platform; 52. Upper die base; 521. Sliding sleeve; 53. Lower die base; 531. Sliding rod; 532. Return spring (1); 54. Trimming ring; 55. Lower die core; 551. Lower cutter hole; 552. Air jet microhole; 56. Upper die core; 561. Upper cutter hole; 562. Electromagnetic block; 58. Punching knife assembly; 59. Tension spring (1); 6. Adjustment mechanism; 61. Pneumatic cylinder; 611. Air guide interface; 62. Connecting rod; 621. Upper bevel plate; 63. Piston; 631. Air flow channel; 632. Stopper (1); 64. Adjustment ring; 641. Lower bevel plate; 642. Eccentric air port; 643. Stopper (2); 65. Tension spring (2); 66. Magnetic plunger; 661. Return spring (2); 7. Board. DETAILED DESCRIPTION

[0017] The embodiments will be combined with the drawings in the specification to clearly and completely describe the technical solution of this application. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without making any creative work shall fall within the scope of protection of this application.

[0018] 1. Example 1: The present invention provides a fuel cell bipolar plate, see Figure 1 - Figure 6, including a bipolar plate 1, the bipolar plate 1 is annular, and the bipolar plate 1 is divided into a high-position sector 11 and a low-position sector 13 according to the height difference. Two groups of connecting sectors 12 are symmetrically arranged between the high-position sector 11 and the low-position sector 13; the cross-section of the high-position sector 11 gradually decreases in height from the center of the circle toward the circumference, and has a tendency to drive water to flow from the center of the circle to the circumference; the cross-section of the low-position sector 13 gradually decreases in height from the circumference toward the center of the circle, and has a tendency to drive water to flow from the circumference toward the center of the circle, and the heights on both sides of the high-position sector 11 are higher than the heights on both sides of the low-position sector 13, and the connecting sector 12 smoothly connects the two sides of the high-position sector 11 and the low-position sector 13, and has a tendency for water to flow from the high-position sector 11 to the low-position sector 13. An input hole 14 is provided at the highest point of the high-order sector 11 , and an output hole 16 is provided at the lowest point of the low-order sector 13 . Two groups of symmetrically arranged high-level water guide grooves 111, connecting water guide grooves 121 and low-level water guide grooves 131 are respectively provided on the upper and lower sides of the high-level sector 11, the connecting sector 12 and the low-level sector 13. The input end of the high-level water guide groove 111 is connected to the input hole 14, the output end of the low-level water guide groove 131 is connected to the output hole 16, and the output end of the high-level water guide groove 111 is connected to the input end of the low-level water guide groove 131 through the connecting water guide groove 121. The high-position water guide groove 111 and the low-position water guide groove 131 perform serpentine circulation along the circumferential direction, and the connecting water guide groove 121 performs serpentine circulation along the radial direction.

[0019] The bipolar plate 1 of the present invention adopts a circular ring design and is divided into a high-position sector 11, a low-position sector 13 and a connecting sector 12. Combined with a serpentine water guide groove, it is beneficial to the discharge of water and the uniform distribution of gas, reduces the occurrence of "water blockage" phenomenon, and improves the reaction efficiency and stability of the fuel cell.

[0020] A positioning hole 15 is further provided at the center of the bipolar plate 1 , and multiple bipolar plates 1 are sleeved on the central shaft 3 through the positioning hole 15 . The central shaft 3 is also provided with an input tube 31 and an output tube 32 matching the input hole 14 and the output hole 16 . A connector 2 is also fixed to the circumferential side of the bipolar plate 1. The connector 2 includes a planar ring 21. Several snap grooves 23 and snaps 24 evenly distributed at equal angles are fixed on the upper and lower sides of the planar ring 21. Two sets of sealing gaskets 22 are fixed on the upper and lower sides of the planar ring 21.

[0021] The design of the positioning hole 15 and the central shaft 3 facilitates the assembly of multiple bipolar plates 1. The cooperation between the input pipe 31 and the output pipe 32 and the input hole 14 and the output hole 16 realizes the centralized transportation of fluid and simplifies the overall structure of the fuel cell. The buckle groove 23, buckle 24 and sealing gasket 22 on the connector 2 facilitate the connection and sealing between adjacent bipolar plates 1, improve assembly efficiency and sealing, and reduce the risk of fluid leakage.

[0022] For further information, see Figure 4 The bipolar plate 1 includes a metal base layer 101 from the inside out according to the material, and a gradient transition layer 102 is provided on both sides of the metal base layer 101. A conductive coating 103 is provided on the side of the gradient transition layer 102 away from the metal base layer 101. The thickness of the metal base layer 101 is 0.15-0.2 mm. The gradient transition layer 102 has a Cr-CrN-CrCN gradient structure, with the Cr content gradually decreasing from the metal base layer to the side away from it, while the N and C content gradually increase. Specifically, the total thickness of the gradient transition layer 102 is 1.8-3.5μm. The inner layer, close to the metal base layer, is primarily Cr, 1-2μm thick, and contains 80-90% Cr. The middle layer is primarily CrN, 0.5-1μm thick, with a CrN phase ratio of 60%-70%. The outer layer, further from the metal base layer, is primarily CrCN, 0.3-0.5μm thick, with a CrCN phase ratio of 50%-60%. Conductive coating 103 is a graphene / carbon nanotube composite film, with nanometal particles embedded in its surface layer. The graphene sheets in conductive coating 103 have a diameter of 10-20 μm, the carbon nanotubes have a diameter of 5-10 nm, and the mass ratio of the graphene and carbon nanotubes is 3:1. The composite film is 1-2 μm thick. The nanometal particles are platinum particles with a diameter of 2-5 nm and a loading of 0.1-0.3 mg / cm².

[0023] The composite structure of the metal substrate layer 101, the gradient transition layer 102, and the conductive coating 103 provides the bipolar plate with excellent electrical conductivity, mechanical strength, and corrosion resistance. The gradient structure of the gradient transition layer 102 effectively solves the problem of insufficient bonding between the metal substrate and the conductive coating, extending the service life of the bipolar plate. The graphene / carbon nanotube composite film and platinum particles in the conductive coating 103 significantly improve the conductivity and catalytic activity of the bipolar plate, reduce the contact resistance, and increase the output power of the fuel cell.

[0024] In this embodiment, during fuel cell operation, reactant gases such as hydrogen and oxygen enter the reaction zone through the gas slots on the bipolar plate 1. Hydrogen flows from the gas slot on the anode side, and oxygen flows from the gas slot on the cathode side. Under the action of the catalyst, the hydrogen undergoes an oxidation reaction at the anode to produce protons and electrons. The protons pass through the proton exchange membrane to the cathode, and the electrons flow through the external circuit to form an electric current. At the cathode, the oxygen combines with the protons and electrons to undergo a reduction reaction to produce water. The generated water is discharged through the high-level water trough 111, the connecting water trough 121 and the low-level water trough 131. Due to the height difference between the high-level sector 11 and the low-level sector 13, and the serpentine design of the water trough, under the push of gravity and gas flow, the water can smoothly flow from the side of the input hole 14 to the side of the output hole 16 and be discharged. The metal matrix layer 101 of the bipolar plate 1 provides good conductivity and mechanical support. The gradient transition layer 102 enhances the bonding between the metal matrix and the conductive coating, while improving the corrosion resistance of the bipolar plate. The graphene / carbon nanotube composite film and platinum particles in the conductive coating 103 further enhance the conductivity and catalytic activity of the bipolar plate, ensuring efficient current conduction. Multiple bipolar plates 1 are sleeved on the central shaft 3 through the positioning holes 15. The input pipe 31 and the output pipe 32 cooperate with the input hole 14 and the output hole 16 respectively to realize the centralized transportation and discharge of the reaction gas and water. The buckle groove 23 and the buckle 24 on the connector 2 are used for connecting and fixing the bipolar plates. The sealing gasket 22 ensures the sealing of the connection to prevent gas and water leakage. 2. Example 2: The present invention provides a method for processing a fuel cell bipolar plate. Figure 1 - Figure 17 , wherein the components identical or corresponding to those in Example 1 are designated by the corresponding reference numerals in Example 1. For simplicity, only the differences from Example 1 are described below: The specific steps include: S1. Use a punching mechanism to punch out a metal base layer 101 from the plate 7 and weld the prefabricated connector 2. After annealing the metal base layer 101 and the connector 2, use anodization to nano-etch the upper and lower sides of the metal base layer 101 to form columnar pits with a diameter of 50-100nm. S2. Using PECVD technology, by controlling the gas flow ratio of Ar, N2, and CH4, a gradient transition layer 102 is deposited on the surface of the metal base layer 101. The vacuum degree of PECVD deposition is 1×10⁻³Pa, the power is 300-400W, and the gradient is achieved by the following methods: When depositing the inner layer, N2 / CH4=0, Ar flow rate 50sccm; When depositing the middle layer, N2 / CH4=10 / 1, Ar flow rate 40sccm; When depositing the outer layer, N2 / CH4=5 / 1, Ar flow rate 30sccm. S3. Electrophoretically deposit a graphene / carbon nanotube composite film. After thermal reduction, pulse electrodeposition is used to load nanometal particles to form a conductive coating 103 on the surface of the gradient transition layer 102. The electrophoretic deposition parameters are as follows: graphene and carbon nanotubes are dispersed in an ethanol-water mixture at a volume ratio of 1:1, voltage 15V, deposition time 10 minutes; thermal reduction is performed by heating at 300°C in an N2 atmosphere for 1 hour; pulse electrodeposition uses a 0.01 mol / L H2PtCl6 solution, a 50 Hz pulse current, a peak current density of 10 mA / cm², and a deposition time of 30 seconds. S4. A femtosecond laser is used to etch gas grooves on both sides of the high water guide groove 111, the connecting water guide groove 121, and the low water guide groove 131 to match the flow directions of the high water guide groove 111, the connecting water guide groove 121, and the low water guide groove 131, and a super-hydrophobic coating is applied to the high water guide groove 111, the connecting water guide groove 121, and the low water guide groove 131. The femtosecond laser has a pulse width of 100 fs and a power of 50 W. Please refer to the Figure 7 - Figure 17 The blanking mechanism includes a transmission mechanism 4, which serves as a blanking base and conveys the plate 7; a clamping mechanism 5 arranged on the transmission mechanism 4, which is used to punch the metal base layer 101 from the plate 7 and stamp it into shape; and an adjustment mechanism 6 arranged on the clamping mechanism 5, which is used to control the height position of the plate 7 conveyed by the transmission mechanism 4. Please refer to the Figure 8 - Figure 10 The clamping mechanism 5 includes a lower mold base 53 fixed on the transmission mechanism 4, a lower mold core 55 is fixed on the top of the lower mold base 53, and slide rods 531 are symmetrically fixed on both sides of the top of the lower mold base 53. An upper mold base 52 is provided on the top of the lower mold base 53, and sliding sleeves 521 matching the slide rod 531 are provided on both sides of the upper mold base 52. A return spring 532 is sleeved on the slide rod 531. An upper mold core 56 is fixed to the bottom of the upper mold base 52, and a pressure platform 51 is slidably connected to the top of the upper mold base 52. The top of the pressure platform 51 is connected to the output end of the hydraulic mechanism, and a tensioning spring 59 is also fixed between the pressure platform 51 and the upper mold base 52. It should be noted that the surfaces of the lower mold core 55 and the upper mold core 56 are both provided with convex molds that match the high-position water guide groove 111 , the connecting water guide groove 121 and the low-position water guide groove 131 .

[0025] A punching knife group 58 and a trimming ring knife 54 are fixed to the bottom of the pressure platform 51 respectively. The inner diameter of the punching knife group 58 is equal to the outer diameter of the upper mold core 56. The upper mold core 56 is provided with an upper knife hole 561 matching the punching knife group 58, and the lower mold core 55 is provided with a lower knife hole 551 corresponding to the punching knife group 58.

[0026] Please refer to the Figure 16The transmission mechanism 4 includes a base 41, and the top of the base 41 is connected to a lifting seat 421 for sliding in the vertical direction. Two groups of plate conveyor belts 42 are symmetrically arranged on the top of the lifting seat 421. Four groups of height cylinders 43 are also fixed on the base 41. The output end of the height cylinder 43 is fixedly connected to the lifting seat 421. The lifting seat 421 is also fixed with two groups of symmetrically arranged side guide rollers 422 on both sides of the clamping mechanism 5. The base 41 is provided with a scrap conveyor belt 44 at the bottom of the lower mold core 55 , and the lifting base 421 is further provided with a finished product conveyor belt 45 between the plate conveyor belt 42 and the scrap conveyor belt 44 . Please refer to the Figure 10 - Figure 17 The adjusting mechanism 6 includes two groups of pneumatic cylinder bodies 61 symmetrically fixed on the top of the upper mold base 52. A one-way valve is provided on the top of the pneumatic cylinder body 61 for one-way air intake. The top of the slide rod 531 extends into the pneumatic cylinder body 61 and is fixed with a piston 63. The pneumatic cylinder body 61 is provided with an air guide interface 611 on the bottom side of the piston 63. The air guide interface 611 is connected to the cylinder body of the height cylinder 43 through a pipeline.

[0027] Please refer to the Figure 13 The top of the lower mold core 55 is also provided with a plurality of inclined air injection micro holes 552.

[0028] Please refer to the Figure 11 - Figure 12 The top of the piston 63 is connected to the regulating ring 64 for rotational limiting, and two groups of symmetrically arranged limiting blocks 643 are fixed on the circumferential side of the regulating ring 64. A limiting block 1 632 corresponding to the limiting block 2 643 is provided in the piston 63, and a tensioning spring 2 65 is clamped between the limiting block 2 643 and the limiting block 1 632. An air flow channel 631 is provided in the piston 63 and the lower die base 53, and the output end of the air flow channel 631 is connected to the input end of the air injection microhole 552 and a valve mechanism is provided at the connection between the two. An eccentric air port 642 corresponding to the input end of the air flow channel 631 is provided on the regulating ring 64. Two sets of rotationally symmetrical lower bevel plates 641 are fixed to the top of the adjustment ring 64 , a connecting rod 62 is fixed to the inner top of the pneumatic cylinder 61 , and an upper bevel plate 621 matching the lower bevel plates 641 is provided at the bottom of the connecting rod 62 . When the second tensioning spring 65 is in a free state, the eccentric air port 642 and the input end of the air flow channel 631 are offset and closed. The valve mechanism includes a magnetic plunger 66 that is slidably connected to the lower mold base 53 in the vertical direction. A return spring 661 is clamped between the top of the magnetic plunger 66 and the lower mold base 53. An electromagnetic block 562 that cooperates with the magnetic plunger 66 is fixed in the upper mold core 56. When the upper die seat 52 moves up, the sheet conveyor 42 drives the sheet 7 to automatically move up and away from the surface of the lower die core 55, avoiding excessive friction on the surface of the lower die core 55 during the transportation of the sheet 7. During the continuous downward movement of the upper mold base 52, when the upper mold core 56 and the lower mold core 55 initially clamp the plate 7, the upper mold core 56 can no longer move downward. At this time, the pressure of the hydraulic mechanism is output to the pressure platform 51, and the punching knife group 58 and the trimming ring knife 54 are used to punch out the plate 7 to form the initial shape of the metal base layer 101. When the pressure platform 51 moves down to the maximum stroke, the pressure platform 51 is flush with the top of the upper mold base 52. At this time, the pressure of the hydraulic mechanism is simultaneously transmitted to the pressure platform 51 and the upper mold base 52, and the upper mold core 56 and the lower mold core 55 are matched to make the metal base layer 101 stamped and formed, and the high-position water guide groove 111, the connecting water guide groove 121 and the low-position water guide groove 131 grooves are pressed out.

[0029] During the punching process, the waste material punched out by the punching knife group 58 is expelled through the lower knife hole 551 of the lower die core 55 and is received and transported by the waste material conveyor belt 44 at the bottom thereof, which can effectively prevent the occurrence of blockage of the punching waste material.

[0030] On the other hand, during the process of the upper die holder 52 gradually moving downward, the chamber of the pneumatic cylinder 61 located at the top of the piston 63 is in a positive pressure state and is gradually pressurized. When the upper die holder 52 moves down to its full position, the lower bevel plate 641 of the adjusting ring 64 abuts against the upper bevel plate 621 of the connecting rod 62. The upper bevel plate 621 abuts against the lower bevel plate 641, causing the adjusting ring 64 to rotate against the elastic force of the second tensioning spring 65, causing the eccentric air port 642 to align with the input end of the air flow channel 631. At this time, the positive air pressure in the pneumatic cylinder 61 enters the air flow channel 631 and is intercepted by the valve mechanism. It should be noted that since the trimming ring knife 54 and the punching knife group 58 are punching downward, the edge side of the metal base layer 101 will be slightly bent downward and covered on the lower mold core 55. Due to the friction of this part, the metal base layer 101 always stays on the lower mold core 55 during the demolding process.

[0031] When the upper die holder 52 moves up to the designed height, that is, when the sheet conveyor belt 42 drives the sheet 7 to move up to the designed height, during this process, the sheet 7 is conveyed, and the conveying distance is half the distance of the metal matrix layer 101, so that half of the punching notch on the sheet 7 covers the top of the lower die core 55. At the same time, the electromagnetic block 562 is energized, causing the magnetic plunger 66 to overcome the elastic force of the return spring 2 661 and displace, opening the air flow channel 631. At this time, air pressure enters the air injection micropores 552, separating the metal matrix layer 101 formed on the lower die core 55. On the other hand, the magnetic force of the electromagnetic block 562 penetrates the punching notch of the plate 7 to assist in the upward and separation of the metal base layer 101. Since the air jet micropores 552 are set obliquely, the metal base layer 101 can be effectively blown obliquely into the bottom of the plate 7 and adsorbed by the electromagnetic block 562 at the bottom of the plate 7. At this time, the plate 7 continues to move forward and drives the metal base layer 101 to move. As the upper mold base 52 continues to move upward, the magnetic force and the air pressure in the air jet micropores 552 are weakened, and finally the metal base layer 101 falls into the finished product conveyor belt 45 for finished product transportation.

[0032] The processing method of the present invention adopts a blanking mechanism to realize the rapid blanking and forming of the metal base layer 101, has a complete plate 7, waste material, and finished product conveying mechanism, has high processing efficiency, and adopts a combination of PECVD technology, electrophoretic deposition, pulsed electrodeposition and other processes, which can accurately control the composition and structure of the coating to ensure the stability of the coating performance. The process of femtosecond laser etching gas grooves and applying super-hydrophobic coating improves the processing quality of the flow channel and the flow performance of the fluid. The entire processing process has a high degree of automation, which can ensure the consistency and stability of the product and is suitable for promotion and application.

[0033] The above is only the best implementation method adopted by this application in combination with current actual needs, but the scope of protection of this application is not limited to this.

Claims

1. A fuel cell bipolar plate, characterized in that: The bipolar plate (1) is annular and is divided into a high-position sector (11) and a low-position sector (13) according to a height difference. Two groups of connecting sectors (12) are symmetrically provided between the high-position sector (11) and the low-position sector (13). An input hole (14) is provided at the highest point of the high-position sector (11), and an output hole (16) is provided at the lowest point of the low-position sector (13). Two groups of symmetrically arranged high-position water guide grooves (111), connecting water guide grooves (121) and low-position water guide grooves (131) are provided on the upper and lower sides of the high-position sector (11), the connecting sector (12) and the low-position sector (13). The input end of the high-position water guide groove (111) is connected to the input hole (14), the output end of the low-position water guide groove (131) is connected to the output hole (16), the output end of the high-position water guide groove (111) is connected to the input end of the low-position water guide groove (131) via the connecting water guide groove (121), the high-position water guide groove (111) and the low-position water guide groove (131) are serpentine-circulated in the circumferential direction, and the connecting water guide groove (121) is serpentine-circulated in the radial direction. The center portion of the bipolar plate (1) is further provided with a positioning hole (15), and a plurality of the bipolar plates (1) are sleeved on the central shaft (3) through the positioning hole (15). The central shaft (3) is further provided with an input tube (31) and an output tube (32) that match the input hole (14) and the output hole (16).

2. A fuel cell bipolar plate according to claim 1, characterized in that: The cross section of the high-position sector (11) gradually decreases in height from the center of the circle toward the circumference, and the cross section of the low-position sector (13) gradually decreases in height from the circumference toward the center of the circle, and the heights of both sides of the high-position sector (11) are higher than the heights of both sides of the low-position sector (13), and the connecting sector (12) smoothly connects both sides of the high-position sector (11) and the low-position sector (13); A connecting member (2) is also fixed to the circumferential side of the bipolar plate (1), and the connecting member (2) includes a planar ring (21). A plurality of snap grooves (23) and snaps (24) arranged evenly at equal angles are fixed on the upper and lower sides of the planar ring (21). Two sets of sealing gaskets (22) are fixed on the upper and lower sides of the planar ring (21).

3. A fuel cell bipolar plate according to claim 2, characterized in that: The bipolar plate (1) comprises a metal base layer (101) in order from the inside out according to the material, a gradient transition layer (102) is provided on both sides of the metal base layer (101), and a conductive coating (103) is provided on the side of the gradient transition layer (102) away from the metal base layer (101); The thickness of the metal base layer (101) is 0.15-0.2 mm; The gradient transition layer (102) is a Cr-CrN-CrCN gradient structure, and from the side close to the metal base layer to the side away from it, the Cr element content gradually decreases, and the N and C element contents gradually increase. Specifically, the total thickness of the gradient transition layer (102) is 1.8-3.5 μm, wherein: the inner layer close to the metal base layer is mainly Cr, with a thickness of 1-2 μm and a Cr content of 80-90 at%; the middle layer is mainly CrN, with a thickness of 0.5-1 μm, and a CrN phase proportion of 60%-70%; the outer layer away from the metal base layer is mainly CrCN, with a thickness of 0.3-0.5 μm, and a CrCN phase proportion of 50%-60%; The conductive coating (103) is a graphene / carbon nanotube composite film, and the surface layer of the conductive coating (103) is embedded with nano-metal particles. The diameter of the graphene sheets in the conductive coating (103) is 10-20 μm, the diameter of the carbon nanotubes is 5-10 nm, the mass ratio of the two is 3:1, and the thickness of the composite film is 1-2 μm. The nano-metal particles are platinum particles with a particle size of 2-5 nm and a loading amount of 0.1-0.3 mg / cm.

4. A method for processing a fuel cell bipolar plate, applicable to the fuel cell bipolar plate according to claim 3, characterized in that: The following steps are involved: S1. Using a punching mechanism, a metal base layer (101) is punched out from a plate (7), and a prefabricated connector (2) is welded thereto. After annealing the metal base layer (101) and the connector (2), nano-etching is performed on the upper and lower sides of the metal base layer (101) using an anodic oxidation method to form columnar pits with a diameter of 50-100 nm. S2. Using PECVD technology, by controlling the gas flow ratio of Ar, N2, and CH4, a gradient transition layer (102) is deposited on the surface of the metal base layer (101), wherein the vacuum degree of PECVD deposition is 1×10⁻³Pa, the power is 300-400W, and the gradient is achieved by the following method: When depositing the inner layer, N2 / CH4=0, Ar flow rate 50sccm; When depositing the middle layer, N2 / CH4=10 / 1, Ar flow rate 40sccm; When depositing the outer layer, N2 / CH4=5 / 1, Ar flow rate 30sccm; S3, depositing a graphene / carbon nanotube composite film by electrophoresis, and after thermal reduction, using pulse electrodeposition to load nano-metal particles to form a conductive coating (103) on the surface of the gradient transition layer (102), wherein the parameters of the electrophoretic deposition are: graphene and carbon nanotubes with a volume ratio of 1:1 are dispersed in an ethanol-water mixture, the voltage is 15V, and the deposition time is 10min; thermal reduction is heated at 300℃ in a N2 atmosphere for 1h; pulse electrodeposition uses 0.01mol / LH2PtCl6 solution, 50Hz pulse current, peak current density of 10mA / cm², and deposition time is 30s; S4. Etching gas grooves that match the flow directions of the high-position water guide groove (111), the connecting water guide groove (121) and the low-position water guide groove (131) on both sides of the high-position water guide groove (111), the connecting water guide groove (121) and the low-position water guide groove (131) by using a femtosecond laser, and coating the high-position water guide groove (111), the connecting water guide groove (121) and the low-position water guide groove (131) with a super-hydrophobic coating, wherein the pulse width of the femtosecond laser is 100 fs and the power is 50 W.

5. A fuel cell bipolar plate processing method according to claim 4, characterized in that: The blanking mechanism includes a transmission mechanism (4) serving as a blanking base and conveying a plate (7); A clamping mechanism (5) provided on the transmission mechanism (4) is used for punching out the metal base layer (101) from the plate (7) and forming it by stamping; An adjusting mechanism (6) provided on the mold clamping mechanism (5) is used to control the height position of the plate (7) conveyed by the transmission mechanism (4).

6. A fuel cell bipolar plate processing method according to claim 5, characterized in that: The clamping mechanism (5) includes a lower mold base (53) fixed on the transmission mechanism (4), a lower mold core (55) is fixed on the top of the lower mold base (53), and sliding rods (531) are symmetrically fixed on both sides of the top of the lower mold base (53), an upper mold base (52) is provided on the top of the lower mold base (53), and sliding sleeves (521) matching the sliding rod (531) are provided on both sides of the upper mold base (52), and a return spring (532) is sleeved on the sliding rod (531); An upper mold core (56) is fixed to the bottom of the upper mold base (52), a pressure platform (51) is slidably connected to the top of the upper mold base (52), the top of the pressure platform (51) is connected to the output end of the hydraulic mechanism, and a tension spring (59) is fixed between the pressure platform (51) and the upper mold base (52); A punching knife group (58) and a trimming ring knife (54) are fixed to the bottom of the pressure platform (51), respectively. The inner diameter of the punching knife group (58) is equal to the outer diameter of the upper mold core (56). The upper mold core (56) is provided with an upper knife hole (561) matching the punching knife group (58), and the lower mold core (55) is provided with a lower knife hole (551) corresponding to the punching knife group (58).

7. A fuel cell bipolar plate processing method according to claim 6, characterized in that: The transmission mechanism (4) includes a base (41), the top of the base (41) is slidably connected to a lifting seat (421) in the vertical direction, two groups of plate conveyor belts (42) are symmetrically arranged on the top of the lifting seat (421), four groups of height cylinders (43) are fixed on the base (41), the output ends of the height cylinders (43) are fixedly connected to the lifting seat (421), and the lifting seat (421) is also fixed with two groups of symmetrically arranged side guide rollers (422) on both sides of the clamping mechanism (5); The base (41) is provided with a waste conveyor belt (44) at the bottom of the lower mold core (55), and the lifting seat (421) is further provided with a finished product conveyor belt (45) between the plate conveyor belt (42) and the waste conveyor belt (44).

8. The method for processing a fuel cell bipolar plate according to claim 7, characterized in that: The regulating mechanism (6) comprises two groups of pneumatic cylinder bodies (61) symmetrically fixed on the top of the upper die base (52), a one-way valve is provided on the top of the pneumatic cylinder body (61) for one-way air intake, the top of the slide rod (531) extends into the pneumatic cylinder body (61) and is fixed with a piston (63), the pneumatic cylinder body (61) is provided with an air guide interface (611) on one side of the bottom of the piston (63), and the air guide interface (611) is connected to the cylinder body of the height cylinder (43) through a pipeline.

9. A fuel cell bipolar plate processing method according to claim 8, characterized in that: The top of the lower mold core (55) is also provided with a plurality of obliquely arranged air injection micro holes (552); The top of the piston (63) is connected to the regulating ring (64) for limiting rotation, and two groups of symmetrically arranged limiting blocks (643) are fixed on the circumferential side of the regulating ring (64). A limiting block (632) corresponding to the limiting block (643) is provided in the piston (63), and a tensioning spring (65) is clamped between the limiting block (643) and the limiting block (632). An air flow channel (631) is provided in the piston (63) and the lower die base (53), and the output end of the air flow channel (631) is connected to the input end of the air injection microhole (552) and a valve mechanism is provided at the connection between the two. An eccentric air port (642) corresponding to the input end of the air flow channel (631) is provided on the regulating ring (64); Two groups of rotationally symmetrical lower bevel plates (641) are fixed to the top of the adjusting ring (64), a connecting rod (62) is fixed to the inner top of the pneumatic cylinder (61), and an upper bevel plate (621) matching the lower bevel plates (641) is provided at the bottom of the connecting rod (62).

10. The method for processing a fuel cell bipolar plate according to claim 9, characterized in that: When the tension spring 2 (65) is in a free state, the eccentric air port (642) and the input end of the air flow channel (631) are staggered and closed; The valve mechanism includes a magnetic plunger (66) slidably connected to the lower die base (53) in the vertical direction, a second return spring (661) is clamped between the top of the magnetic plunger (66) and the lower die base (53), and an electromagnetic block (562) that matches the magnetic plunger (66) is fixed in the upper die core (56).

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