Method for manufacturing fuel cell metal separator plates and multi-stage molding production line for metal separator plates

Abstract

A method for manufacturing a fuel cell metal separator plate and a multi-stage forming production line for a metal separator plate are disclosed. The method for manufacturing a fuel cell metal separator plate comprises: an input process in which a metal substrate having a thickness of less than 0.2 mm is input into a first press device equipped with a first forming die; a first forming process in which a first press pre-forming is performed on the metal substrate using the first press device to form a pre-formed metal separator plate; a transfer and electro-processing process in which a transfer electro-processing device moves the pre-formed metal separator plate to an electro-processing station of the transfer electro-processing device, performs electro-processing such that the clamping area during electro-processing exceeds 500 mm², and controls the electro-processed metal separator plate to be discharged after the electro-processing is completed; a second forming process in which a second press forming is performed on the electro-processed metal separator plate using a second press device to obtain a fully formed metal separator plate; and a discharge process in which the fully formed metal separator plate is discharged from the second press device.

Description

Technology Field

[0001] The present application relates to the field of fuel cells, and more specifically, to a multi-stage forming production line for metal separators based on an electric treatment reforming effect and the process thereof, in particular to a method for manufacturing a fuel cell metal separator and a multi-stage forming production line for metal separators. Background Technology

[0002] Hydrogen energy is a crucial strategic means of driving the green transition of the global energy industry, and proton exchange membrane fuel cells (PFCs) are a core technology for hydrogen energy utilization. High power output, long lifespan, and high performance are the development trends for fuel cells. As a key component of fuel cells, bipolar plates possess sub-millimeter-scale microchannel characteristics, and the precision of these channels significantly impacts the power generation efficiency, reliability, and service life of the fuel cell. Compared to conventional graphite bipolar plates, metal bipolar plates combine various advantages such as small thickness, low cost, excellent mechanical performance, and superior electrical and thermal conductivity, making them one of the mainstream trends in the development of fuel cell manufacturing technology.

[0003] However, as demands for reaction gas and product water transport efficiency in fuel cells continue to rise, bipolar plates must possess more precise flow channel structures and higher depth-to-width ratios. Furthermore, the limitations of the formability of ultra-thin metal substrates lead to premature cracking during the press forming process, thereby restricting the advancement of high-performance fuel cells. Over the past few years, extensive innovations have been made in the forming methods of metal bipolar plates both domestically and internationally. Novel laboratory-level processes, such as electromagnetic high-speed forming and high-temperature forming, can effectively improve the formability of metal separator plates; however, they all exhibit problems such as low production efficiency and poor compatibility with existing bipolar plate production lines, which limits their application in actual production. Therefore, there is a need to develop a manufacturing method for high-performance metal bipolar plates for fuel cells that is efficient and simply compatible with existing metal separator production lines.

[0004] Patent document CN112974642A (electrically assisted forming apparatus and process for fuel cell metal separator plates) discloses an electrically assisted forming process for fuel cell metal separator plates that lowers the forming force of the separator plates and improves forming precision and consistency by utilizing Joule heating and electroplastic effects by applying current to the metal separator plates that remain in the mold during the press forming process of the metal separator plates. However, the electrically assisted forming process according to the above invention focuses on improving the manufacturing precision of the single-stage press forming of the metal separator plates, and does not have a significant improvement effect regarding the forming limit of the metal separator plates.

[0005] Patent document CN111842611A (Apparatus and method for forming titanium alloy bipolar plate based on multi-stage sequence pulse current) proposed an electromagnetic-thermal composite forming method for titanium alloy bipolar plates that improves the forming limit of titanium alloy separator plates by utilizing thermal effects, electroplastic effects, and high strain effects of pulsed electromagnetic force through multi-stage sequence pulse current discharge. However, the electromagnetic forming apparatus included in the above technology is complex, requires high costs, and has low production efficiency, making it unsuitable for actual production applications.

[0006] Patent document CN116154208B (High-precision, high-corrosion-resistant titanium bipolar plate for fuel cells and method for manufacturing the same, mold assembly) proposed a heat-assisted forming process for an ultra-thin titanium separator plate for fuel cells, which improves re-deformation performance and enhances forming limits by adding an annealing heat treatment process between two-stage press forming processes to release internal stress and remove work hardening of the titanium separator plate after the first forming. However, the heat treatment process according to the invention is relatively long (2 to 30 min), which affects the production efficiency of the titanium separator plate. In addition, grain growth often accompanies the static recovery process of the heat treatment, which limits the effect of improving the forming limit of the separator plate. The problem to be solved

[0007] Considering the shortcomings of the aforementioned existing technology, the present invention proposes a multi-stage metal separator forming production line and process based on electro-treatment modification that significantly improves the forming limits and forming precision of metal separators, thereby resolving problems such as insufficient microchannel depth, channel cracking, and reduced dimensional precision present in existing metal separator forming processes, and ensuring that production efficiency is not affected. means of solving the problem

[0008] To achieve the above-mentioned objective, the present invention provides a method for manufacturing a fuel cell metal separator plate based on electro-processing modification and a multi-stage metal separator plate forming production line, wherein the multi-stage metal separator plate forming production line sequentially comprises an input robot (input device), a first press device, a transfer electro-processing device, an electro-processing device, a second press device, and an output robot (output device).

[0009] At the same time, the present invention proposes a multi-stage metal separator forming production process based on the following electro-processing modification, centered on the aforementioned production line,

[0010] Material acquisition process (S1): A titanium substrate or a ferritic stainless steel substrate having a thickness of 0.05 mm or more and 0.2 mm or less is acquired, and

[0011] Process for obtaining electrical treatment parameters (S2): Electrical treatment refers to a material modification process that applies a direct current to a metal separator to restore its internal defects and thereby express its plasticity. Compared to conventional in-furnace annealing heat treatment, the ultra-short electrical treatment releases internal stress, thereby removing deformation twins and dislocation accumulation generated during the pre-deformation process of the ultra-thin metal plate, and significantly promoting static recrystallization, thus improving the re-deformation performance of the pre-deformed metal separator and enhancing the forming limit. The electrical treatment device can provide a constant voltage direct current or a pulse direct current of an arbitrary waveform, with an output voltage amplitude of 0 to 300 V, a duty cycle of 0 to 100%, and a frequency of 100 to 4000 Hz.

[0012] For separator plates of different dimensions, the input electrical energy required to treat defects varies; since the temperature rise of the separator plate due to the Joule heating effect of electrical treatment is easy to measure, it can be used as a means to simply determine the electrical energy input level and to determine the threshold values ​​of electrical treatment parameters. The target temperature range for electrical treatment is 500–1200°C, and the energization time must be controlled within the range of 0.5–10 seconds. In actual production, the electrical treatment time must first be selected based on production takt requirements, and then electrical treatment process parameters such as output voltage, duty cycle, and frequency must be determined based on the target heating temperature.

[0013] Input process (S3): The input robot automatically transfers the material plate to the first press device through the vacuum suction pad and positions the material plate within the first molding die, and

[0014] First forming process (S4): The press is lowered, and preliminary forming is performed on the metal material plate through the first forming die to obtain a metal separator plate, and

[0015] Transfer and Electric Processing Process (S5): The transfer and electric processing device first adsorbs the pre-formed metal separator plate through a vacuum suction pad and transfers it out of the first press device. Subsequently, it is moved to the position of the electric processing clamp integrated into the transfer and electric processing device, and the upper clamp head of the electric processing clamp is lowered to clamp both ends of the pre-formed metal separator plate, and the vacuum suction pad is stopped and moved upward. The electric processing clamp is made to clamp the pre-deformed metal separator plate to complete the transfer operation between the two press devices, and at the same time, electric processing modification is performed on the pre-deformed metal separator plate, ensuring that the electric processing modification of the metal separator plate is completed and cooled to room temperature before reaching the second press device. Finally, the vacuum suction pad is lowered to adsorb the metal separator plate, the electric processing clamp is released and returns, and the metal separator plate is transferred to the second press device and positioned.

[0016] Second forming process (S6): The press is lowered, and full press forming is performed on the electrically processed pre-formed metal separator plate through the second forming mold, and

[0017] Outgoing process (S7): The outgoing robot is made to move the fully formed metal separator plate out of the second press device.

[0018] A feeding process for feeding a metal substrate with a thickness of less than 0.2 mm into a first press device equipped with a first forming die;

[0019] A first forming process for forming a preformed metal separator plate by performing a first press preformation on the metal substrate using a first press device;

[0020] The transfer electric processing device moves the pre-formed metal separator plate to the electric processing station of the transfer electric processing device, and the clamping area during the electric processing is 500 mm 2Exceeding, and furthermore, 1500 mm 2 Exceeding, and furthermore, 2000 mm 2 A transfer and electro-processing process that performs electro-processing to exceed [value] and controls the removal of the electro-processed metal separator plate after the electro-processing is completed;

[0021] A second forming process for obtaining a fully formed metal separator plate by performing a second press forming on the electrotreated metal separator plate using a second press device; and

[0022] A method for manufacturing a fuel cell metal separator is provided, comprising: a removal process for removing the fully formed metal separator from the second press device.

[0023] In a preferred embodiment, at least one intermediate forming process for performing press forming on a metal separator plate is further included between the first forming process and the second forming process, and the electrical treatment process is provided between both forming processes.

[0024] In a preferred embodiment, the transfer electric processing device comprises an electric processing support platform and a transfer platform located above the electric processing support platform, wherein the electric processing support platform comprises electrode units installed opposite each other, and the electrode units comprise electrode clamps that are operablely pressed and opened, and the transfer platform is mounted above the electric processing support platform via a vertical moving support, and the transfer platform is installed on the vertical moving support so as to be operable to move up and down, and the transfer platform comprises a rectangular frame and an adsorption pad assembly installed on the rectangular frame so as to be operable to move in one horizontal direction, and the adsorption pad assembly is used to adsorb a metal substrate or a metal separator plate.

[0025] The above-described adsorption pad assembly has a first horizontal position (initial position) and a second horizontal position in one horizontal direction with respect to the rectangular frame, and the transfer platform has a first height position and a second height position located above the first height position on the vertical moving support (5).

[0026] In a preferred embodiment, during a transfer and electro-processing process, the adsorption pad assembly is controlled to adsorb a pre-formed metal separator plate at the second horizontal position and the second height position, then the electrode clamp is opened, and the adsorption pad assembly is controlled to descend to the first height position and then move from the second horizontal position to the first horizontal position, then the pre-formed metal separator plate is transferred between the electrode clamps, and the electrode clamp is controlled to press the pre-formed metal separator plate while the adsorption pad assembly is controlled to release the pre-formed metal separator plate to perform electro-processing, and finally the electrode clamp is opened and the adsorption pad assembly is controlled again to adsorb the electro-processed metal separator plate and move from the first horizontal position to the second horizontal position, and then the electro-processed metal is moved upward to the second height position.

[0027] In a preferred embodiment, during the input process, a manipulator controls the metal substrate to be fed into the first press device, and after the first forming process is completed, to be discharged from the first press device.

[0028] After the above transfer and electro-processing processes are completed, the electro-processed metal separator plate is also transferred to a second press device via a manipulator, and

[0029] During the removal process, the manipulator controls the removal of the fully formed metal separator plate from the second press device.

[0030] In a preferred embodiment, the process further includes an electrical treatment parameter acquisition process for acquiring an electrical treatment parameter such that the maximum temperature of the pre-formed metal separator plate is 500 to 1200°C when the electrical treatment time is ended and the current is cut off, and the electrical treatment time is 0.5 to 10 seconds.

[0031] In a preferred embodiment, the temperature of a preformed metal separator plate is monitored under electrical processing conditions using an infrared thermal imaging camera, and

[0032] In a preferred embodiment, the electrical treatment uses a constant voltage DC current or a pulse DC current, wherein the output voltage amplitude is 0 to 300 V, the duty cycle is 0 to 100%, and the frequency is 100 Hz to 4000 Hz.

[0033] In a preferred embodiment, the difference between the maximum and minimum values ​​of the flow channel thickness of the fully formed metal separator is less than 24 μm.

[0034] In a preferred embodiment, a first electric guide rail is installed on the electric processing support platform, and the electrode clamp includes a lower electrode with both ends fixedly connected to the first electric guide rail and an upper electrode with both ends movably connected to the electric guide rail, and the first electric guide rail is movable so that the upper electrode moves up and down to open and close the electrode clamp.

[0035] The above transfer platform includes an electric telescopic guide rail installed on the lower side of a rectangular frame, and the suction pad assembly is connected between two electric telescopic guide rails and driven to switch between a first horizontal position (initial position) and a second horizontal position.

[0036] The vertical moving support (5) includes two second electric guide rails installed vertically on the electric processing support platform, and the rectangular frame is vertically connected to the two second electric guide rails and driven to switch between a first height position and a second height position.

[0037] A multi-stage metal separator forming production line for carrying out the above-described method for manufacturing a fuel cell metal separator comprises an input device, a first press device, a transfer electric processing device, a second press device, and an output device.

[0038] The above-mentioned feeding device is used to feed a metal substrate into a first press device equipped with a first forming die, and

[0039] The above first press device is used to perform first press preforming on the metal substrate to form a preformed metal separator plate, and

[0040] The above transfer electric processing device is used to transfer a preformed metal separator plate to an electric processing station of the transfer electric processing device to perform electric processing, and to remove the electrically processed metal separator plate after the electric processing is completed.

[0041] The above second press device is used to perform second press forming on the above electrically treated metal separator plate to obtain a fully formed metal separator plate, and

[0042] The above-described release device provides a metal separator multi-stage forming production line used to release the fully formed metal separator from the second press device. Effects of the invention

[0043] Compared to existing technology, the present invention has the following advantageous effects:

[0044] 1. The method for manufacturing a fuel cell metal separator and the multi-stage forming production line for a metal separator according to the present invention can release internal stress of a pre-formed metal separator and eliminate deformation twins and dislocation accumulation within an extremely short processing time by adding one electrochemical process between two stages of press processes, and ultimately significantly improve the forming limit and forming precision of the metal separator.

[0045] 2. The method for manufacturing a fuel cell metal separator plate and the multi-stage forming production line for a metal separator plate according to the present invention integrates an electric processing device into a transfer electric processing device, thereby allowing the pre-formed metal separator plate to be transferred to the next press process while simultaneously performing electric processing to eliminate deformation twins and dislocation accumulation, thus not affecting production efficiency.

[0046] 3. The method for manufacturing a fuel cell metal separator plate and the metal separator plate multi-stage forming production line based on the proposed electro-treatment modification effect according to the present invention can be obtained by simply modifying an existing serial press automated production line, so the input cost is low and the range of applications is wide.

[0047] Specific embodiments of the present invention are disclosed in detail with reference to the following description and the accompanying drawings, and ways in which the principles of the present invention may be employed are shown. However, it should be understood that the scope of the embodiments of the present invention is not limited thereto.

[0048] Features described and / or illustrated with respect to one embodiment may be used in one or more other embodiments in the same or similar manner, combined with features of other embodiments, or replace features of other embodiments.

[0049] It should be emphasized that when the term "inclusion / containing" is used in this document, it means the presence of a feature, part, step, or component, but does not exclude the presence or addition of one or more other features, parts, steps, or components. Brief explanation of the drawing

[0050] In order to more clearly explain the embodiments of the present invention or the technical methods of the prior art, drawings that need to be used in the description of the embodiments or prior art are briefly introduced below. Clearly, the drawings described below are merely some embodiments of the present invention, and a person skilled in the art can obtain other drawings based on these drawings without creative labor. Figure 1 is a diagram showing the temperature distribution and local temperature history during the microchannel electro-treatment process of the target separator plate in Example 1. FIG. 2 is a diagram showing the flow path cross-sectional design parameters of (a) the first molding die and (b) the second molding die in Example 1. FIG. 3 is a diagram showing (a) a titanium separator plate formed by conventional room temperature multi-stage press molding in Example 1 and (b) a titanium separator plate formed by a novel method according to the present invention. FIG. 4 is a diagram showing the flow channel thickness distribution of (a) a titanium separator plate formed by conventional room temperature multi-stage press molding in Example 1 and (b) a titanium separator plate formed by a novel method according to the present invention. Figure 5 is a bar graph of the total elongation when the specimen is subjected to long-term electric treatment at 550°C. Figures 6 and 7 are bar graphs of total elongation when electric treatment was performed on specimens at 500℃ (E10.5%) / 600℃ (E13.5%) / 700℃ (E16.8%) for 2 seconds, 3 seconds, 5 seconds, or 10 seconds, respectively. Figure 8 is a bar graph of the total elongation when the specimen is rapidly heated to different target temperatures for 2 seconds. Figure 9 is a bar graph of the total elongation when different amounts of preliminary deformation are applied to the specimens and heated to different target temperatures. Figure 10 is a diagram showing a comparison of the results of forming a specimen twice using a single mold and performing intermediate electrical treatment. FIG. 11 is a schematic diagram showing the three-dimensional structure of a transfer electric processing device according to one embodiment of the present invention. Figure 12 is a view of Figure 11 from a different direction. Fig. 13 is a side view of Fig. 11. Figure 14 is a diagram showing a transfer electric processing process using the transfer electric processing device shown in Figure 11. Specific details for implementing the invention

[0051] In order to enable a person skilled in the art to better understand the technical solution of the present invention, the technical solution according to an embodiment of the present invention is described clearly and completely below with reference to the accompanying drawings in the embodiment of the present invention. Clearly, the described embodiment is only a part of the embodiment of the present invention, not all of it. All other embodiments that a person skilled in the art can obtain without creative effort based on the embodiment of the present invention are all within the scope of protection of the present invention.

[0052] Where it is stated that one component is "installed" on another component, it must be explained that the component may be installed directly on the other component, or that there may be other components interposed between the two. Where it is stated that one component is "connected" to another component, the component may be connected directly to the other component, or that there may be other components interposed between the two. The terms "vertical," "horizontal," "left," "right," and similar expressions used herein are for illustrative purposes only and do not imply the only embodiments.

[0053] Unless otherwise defined, all technical and scientific terms used in this document have the same meaning as commonly understood by those skilled in the art to which the present invention pertains. The terms used in this specification are intended only to describe specific embodiments and are not intended to limit the present invention. The term "and / or" as used in this specification includes any and all combinations of one or more of the items listed in relation to it.

[0054] Referring to FIGS. 1 to 14, one embodiment of the present invention provides a method for manufacturing a fuel cell metal separator plate, and correspondingly, to carry out the manufacturing method, the embodiment further provides a metal separator plate multi-stage forming production line. The metal separator plate multi-stage forming production line includes an input device, a first press device, a transfer electric processing device, a second press device, and an output device.

[0055] The above-mentioned input device is used to input a metal substrate into a first press device equipped with a first forming die. The input device uses an input robot, specifically a manipulator. The above-mentioned first press device is used to perform a first press pre-forming on the metal substrate to form a pre-formed metal separator plate. The above-mentioned transfer electric processing device is used to move the pre-formed metal separator plate to the electric processing station of the transfer electric processing device to perform electric processing, and to discharge the electrically processed metal separator plate after the electric processing is completed. The above-mentioned second press device is used to perform a second press forming on the electrically processed metal separator plate to obtain a fully formed metal separator plate. The above-mentioned discharge device is used to discharge the fully formed metal separator plate from the above-mentioned second press device. The discharge device uses a discharge robot, specifically a manipulator. The input manipulator and the discharge manipulator are different manipulators and are installed according to the process stage of the production line. Of course, as a possible method, the input device and the discharge device may use the same manipulator.

[0056] The above-described press devices all include a press and a die. Here, the die structure may use the die disclosed in Publication No. CN116154208A (titled "High-precision, high-corrosion-resistant titanium bipolar plate for fuel cells and method for manufacturing the same, die assembly"), and overlapping parts are not described again. The press uses a precision press, for example, a YKP-630 precision press. The electrical processing device includes a DC power source, a copper electrode, and an insulating bakelite clamp. Here, the electrode and the insulating clamp are integrated into a transfer electrical processing device and are used for gripping and transferring the preformed metal separator plate.

[0057] As illustrated in FIGS. 11 to 14, the present embodiment further provides a transfer electric processing device. The transfer electric processing device comprises an electric processing support platform (1) and a transfer platform (3) located above the electric processing support platform (1), wherein the electric processing support platform (1) comprises electrode units (4) installed opposite each other, and the electrode units (4) comprise electrode clamps that are operablely pressed and opened. The transfer platform (3) is mounted above the electric processing support platform (1) via a vertical movement support (5), and the transfer platform (3) is installed on the vertical movement support (5) so as to be operable to move up and down. The transfer platform (3) comprises a rectangular frame and an adsorption pad assembly (2) installed on the rectangular frame so as to be operable to move in one horizontal direction, and the adsorption pad assembly (2) is used to adsorb a metal substrate or a metal separator plate (100).

[0058] The above-mentioned adsorption pad assembly (2) has a first horizontal position and a second horizontal position in one horizontal direction with respect to the rectangular frame, and the transfer platform (3) has a first height position and a second height position located above the first height position on the vertical moving support (5). The first horizontal position at the second height position is the initial position of the adsorption pad assembly (2).

[0059] Specifically, a first electric guide rail (40) is installed on the electric processing support platform (1). The electrode clamp includes a lower electrode (42) with both ends fixedly connected to the first electric guide rail (40) and an upper electrode (41) with both ends movably connected to the first electric guide rail (40), and the first electric guide rail (40) can drive the upper electrode (41) to move up and down to open and close the electrode clamp. The lower electrode (42) and the upper electrode (41) are copper electrodes.

[0060] The above transfer platform (3) includes an electric retractable guide rail (31) installed on the lower side of a rectangular frame. The adsorption pad assembly (2) is connected between two electric retractable guide rails (31) that are parallel to each other and is driven to switch between a first horizontal position and a second horizontal position. The vertical moving support (5) includes two second electric guide rails (51) installed vertically on the electric processing support platform (1), and the rectangular frame is connected vertically to the two second electric guide rails (51) and is driven to switch between a first height position and a second height position.

[0061] As illustrated in FIG. 14 (a), when the adsorption pad assembly (2) is positioned at the second horizontal position and at the second height position, it is used to adsorb or unload a metal substrate or a metal separator. When the adsorption pad assembly (2) is positioned at the second horizontal position, it is used to switch between the first height position and the second height position, and the second horizontal position is the same as the horizontal position illustrated in FIG. 15 (b). As illustrated in FIG. 14 (b), when the adsorption pad assembly (2) is positioned at the second horizontal position and at the first height position, it can move to the first horizontal position to transfer a metal substrate or a metal separator between open electrode clamps.

[0062] In this embodiment, the method for manufacturing a fuel cell metal separator is,

[0063] A feeding process for feeding a metal substrate having a thickness of 0.05 mm or more and 0.2 mm or less into a first press device equipped with a first forming die;

[0064] A first forming process for forming a preformed metal separator plate by performing a first press preformation on the metal substrate using a first press device;

[0065] The transfer electric processing device moves the pre-formed metal separator plate to the electric processing station of the transfer electric processing device, and the clamping area during the electric processing is 500 mm 2 A transfer and electro-processing process that performs electro-processing to exceed [value] and controls the removal of the electro-processed metal separator plate after the electro-processing is completed;

[0066] A second forming process for obtaining a fully formed metal separator plate by performing a second press forming on the electrotreated metal separator plate using a second press device; and

[0067] The method includes a removal process for removing the fully formed metal separator plate from the second press device. The difference between the maximum and minimum values ​​of the flow channel thickness of the fully formed metal separator plate is less than 24 μm, and the flow channel depth-width ratio is greater than 0.79.

[0068] In another embodiment, the method for manufacturing the fuel cell metal separator plate is not limited to two press forming steps and one intermediate electrolytic treatment step, but may include a multi-stage press process and multiple electrolytic treatment steps. In this way, at least one intermediate forming step is additionally included between the first forming process and the second forming process to perform press forming on the metal separator plate, and the electrolytic treatment step is provided between both forming processes. Through multiple electrolytic treatments, the metal separator plate can ultimately achieve a higher forming limit.

[0069] As illustrated in FIG. 14, during the transfer and electrical processing, first, as illustrated in FIG. 14 (a), the adsorption pad assembly (2) is controlled to adsorb the pre-formed metal separator plate at the second horizontal position and the second height position, and then, as illustrated in FIG. 14 (b) to (c), the electrode clamp is opened and the adsorption pad assembly (2) is controlled to descend to the first height position and then move from the second horizontal position to the first horizontal position, then the pre-formed metal separator plate is transferred between the electrode clamps, and after the adsorption pad assembly (2) releases the pre-formed metal separator plate, as illustrated in FIG. 14 (d), the electrode clamp is controlled to press the pre-formed metal separator plate to perform electrical processing, and the adsorption pad assembly (2) is raised to the initial position (the second horizontal position of the second height position). Finally, the electrode clamp is opened and the adsorption pad assembly (2) returns to the position shown in (d) to adsorb the electrolytic metal separator, then moves from the first horizontal position to the second horizontal position and controls the electrolytic metal to move upward to the second height position.

[0070] During the input process, the manipulator feeds the metal substrate into the first press device, and controls the removal of the pre-formed metal separator plate from the first press device after the first forming process is completed. After the transfer and electro-processing processes are completed, the electro-processed metal separator plate is also transferred to the second press device via the manipulator. During the removal process, the manipulator controls the removal of the fully formed metal separator plate from the second press device.

[0071] The method for manufacturing the above fuel cell metal separator plate further includes an electrical processing parameter acquisition process for acquiring an electrical processing parameter in which the maximum temperature of the pre-formed metal separator plate becomes 500 to 1200°C when the electrical processing time is ended and the current is cut off, and the electrical processing time is 0.5 to 10 seconds. In the electrical processing parameter acquisition process, the temperature of the pre-formed metal separator plate under electrical processing conditions is monitored through an infrared thermal imaging camera.

[0072] The above electrical treatment uses a constant voltage DC current or a pulse DC current, wherein the output voltage amplitude is 0 to 300 V, the duty cycle is 0 to 100%, and the frequency is 100 Hz to 4000 Hz.

[0073] In this embodiment, the thickness of the bipolar plate is small (<0.2 mm), but the electrical processing clamping area is large (500 mm 2 Exceeding, generally 2000 mm 2 Considering the fact that the demand for contact quality between the copper electrode and the metal separator is high, but since the contact is on a rigid surface, errors in surface flatness during the upper / lower electrode processing, assembly errors between the upper / lower electrode and the electrode clamp, and motion errors during the process of the upper electrode moving downward can all cause uneven stress distribution on the clamped surface of the bipolar plate when the electrode is closed. This can lead to problems such as uneven current density due to differences in local contact resistance during the electrical processing of the pre-formed separator, furthermore, electrochemical damage on the contact surface, local bending deformation in the clamping section, and slippage caused by the clamping force not being applied uniformly and effectively.

[0074] To resolve the occurrence of such problems, a rubber pad is additionally installed on the surface of the upper electrode facing the lower electrode to improve stress transfer and increase the actual contact area, thereby ensuring more uniform conductivity and more reliable clamping. The rubber pad is rectangular, and its thickness is smaller than that of the lower electrode. The rubber pad covers the lower surface of the upper electrode among the upper and lower electrodes, and the upper surface area of ​​the lower electrode is larger than the lower surface area of ​​the rubber pad. The end of the metal separator is clamped between the rubber pad and the upper surface of the lower electrode.

[0075] The method for manufacturing a fuel cell metal separator plate and the multi-stage forming production line for a metal separator plate according to an embodiment of the present invention can release internal stress of the pre-formed metal separator plate and eliminate deformation twins and dislocation accumulation within an extremely short processing time by adding one electrolytic process between two stages of press processes, and can ultimately significantly improve the forming limit and forming precision of the metal separator plate.

[0076] In the embodiment of the present invention, the electro-treatment performed on a pre-formed metal separator plate, particularly a titanium separator plate, is a means of adding a material modification step during the process of forming from material into a part, and the purpose is to improve the processability of the material (manufacturability of the part) and further improve the ductility (elongation) verified in FIGS. 5 to 11. In the present invention, the electro-treatment for the metal separator plate (titanium separator plate) is intended to maximize the ductility of the material by, in the most ideal case, completely removing defects such as dislocations and twins and achieving recrystallization, and by replacing deformed grains with completely new equiaxed grains, thereby realizing a higher forming limit of the metal separator plate.

[0077] FIGS. 5 to 10 are verification results obtained by the inventor verifying the action of electric treatment during the metal separator plate forming process. Here, FIG. 5 shows the results of performing multi-stage tensile testing on a titanium substrate with a thickness of 0.1 mm produced at a certain steel mill and measuring the total elongation (i.e., the situation described in Example 3 below). Specifically, the titanium substrate is first tensiled to 15% along the rolling direction, then electric treatment is performed under different electric treatment conditions shown in FIG. 5 (5s@550℃ means that the maximum temperature of the plate reaches 550℃ at the time of disconnection after performing electric treatment for 5 seconds. The maximum temperature of this experimental group is 550℃, but the electric treatment time varies), and finally, a load is applied again to tensile until fracture occurs. The total elongation of the titanium substrate after two tensile tests is calculated and compared with a specimen that was subjected to two tensile tests without any intermediate electrical treatment (i.e., the position indicated by the green dotted line in Fig. 5, where the elongation of the specimen is approximately 35.8%), and the elongation of the specimen under each electrical treatment condition is improved to different degrees. Elongation is an important indicator for evaluating the ductility of a specimen, and since a higher elongation indicates that the material can withstand a greater degree of tensile deformation before fracture, the electrical treatment demonstrates the ability to improve the forming limit of the titanium substrate.

[0078] Figures 6, 7, and 8 show the results of tensile tests on identically similar titanium plates, with only the electrical treatment parameters changed. Likewise, it can be seen that the elongation of the specimens under different electrical treatment conditions improves to different degrees. Figure 9 compares the total elongation after electrical treatment at 2 sec @ 500℃, 600℃, and 700℃, respectively, after changing the amount of pre-deformation (originally only 15%, but now 10%, 15%, and 20% are compared together). Likewise, it can be seen that the electrical treatment is equally effective for samples with different amounts of pre-deformation, and the overall trend of the effect is the same.

[0079] Figure 10 is a comparative result of performing two forming cycles by directly controlling the press depth in a second forming die without using the first forming die of Figure 2. Compared to the conventional simple multi-stage press forming (top photo of Figure 10), the improved process (bottom photo of Figure 10) controls the press depth to approximately 0.25 mm during the first forming cycle, at which point no cracks occur in the separator plate. Subsequently, after performing electrical treatment on the separator plate, it is placed back into the die and fully pressed to a final depth of 0.35 mm. As can be seen from the results shown in Figure 10, pure electrical treatment has a relatively large improvement effect on the forming limit of the sheet metal. In the conventional process, specimens that were not subjected to electrical treatment completely crack and further exceed the forming limit, while the cracking condition of the electrically treated specimens is significantly improved, indicating that electrical treatment is effective in improving the local forming limit.

[0080] The present invention will be described in more detail below through several specific embodiments to facilitate a better understanding of the invention.

[0081] Example 1

[0082] The present embodiment provides a novel method capable of improving the forming limit and cross-sectional thickness distribution uniformity of a metal separator plate, wherein the flow path period of the target separator plate to be formed is 1.2 mm, the draft angle is 5°, the corner curvature radius is 0.1 mm, the depth-to-width ratio is 0.79, and the specific steps are as follows.

[0083] Raw material selection step (S1)

[0084] In this embodiment, the specimen substrate was selected as TA1 industrial pure titanium with a thickness of 0.1 mm and a titanium element content higher than 99.5% produced at a certain steel mill, and the industrial pure titanium was a titanium substrate that obtained an α-phase structure by cold rolling and annealing heat treatment.

[0085] Electrical processing parameter acquisition step (S2)

[0086] To obtain electrical processing parameters, a pre-formed titanium separator was used, and the temperature of the pre-formed titanium separator under electrical processing conditions was monitored using an infrared thermal imaging camera. As shown in Fig. 1, the electrical processing time was selected to be 2 seconds, and the maximum temperature was ensured to be 750°C when the power was cut off after the titanium separator was electrically processed for 2 seconds. In the above example, for a pre-formed titanium separator with a width of 100 mm, the output voltage of the obtained power box was 120 V, the duty cycle was 70%, and the pulse frequency was 300 Hz.

[0087] Input step (S3)

[0088] Using an input robot, the ultra-thin titanium substrate obtained from S1 was transferred to and positioned in the first press device.

[0089] First molding step (S4)

[0090] A first press forming was performed on the material plate fed in S3 using the first forming die shown in Fig. 2a.

[0091] Transfer and electrical processing step (S5)

[0092] Using a vacuum suction pad integrated into the integrated clamp of the transfer electric processing device, the pre-deformed titanium separator obtained from S4 from the first press mold was suctioned and moved to the electric processing station within the integrated clamp. After recognizing that the pre-deformed titanium separator reached a designated position, the servo motor drove the electrode upper clamp head to move downward and clamp the titanium separator. Subsequently, the vacuum pump stopped operation and the suction pad moved upward. While applying the pulse current corrected in S2 to the pre-deformed titanium separator, the robot arm of the transfer electric processing device moved to move the entire integrated clamp to the second press station. After the electric processing was completed, the suction pad lowered and the vacuum pump was restarted, the upper clamp head moved upward to release the titanium separator, and the titanium separator was transferred to the second press device by the vacuum suction pad to complete the positioning.

[0093] Second molding step (S6)

[0094] Second press forming was performed on the titanium separator plate electrotreated in S5 using the second molding die shown in Fig. 2b.

[0095] Export stage (S7)

[0096] The titanium separator plate formed by the ejection device was ejected from the second press device.

[0097] FIG. 3 illustrates a titanium separator microchannel formed by a conventional room-temperature multi-stage molding process and a novel method proposed in this disclosure, respectively. By using the novel method proposed in this invention, the molding limit of the titanium separator can be overcome, and a target separator without cracks can be obtained. As shown in FIG. 4, the uniformity of the thickness distribution of the separator channel was evaluated using the difference method (a method using the difference between the maximum and minimum values). Specifically, nine characteristic locations (each at the rib portion, groove portion, midpoint of the sidewall, and maximum thickness reduction location of the round portion) were selected in each channel profile cycle, and the substrate thickness was measured. It was found that the difference between the maximum and minimum values ​​of the thickness of the titanium separator microchannel manufactured by the conventional multi-stage molding process was large (27.8 μm), and that the excessive thickness reduction at the most vulnerable round portion location (P6) ultimately caused channel cracks. However, the method proposed in the present invention can promote uniform deformation of the material during the molding process, thereby improving the uniformity of the channel thickness and reducing the difference between the maximum and minimum values ​​of the channel thickness to about 21.8 μm.

[0098] Example 2

[0099] In this embodiment, TA1 industrial pure titanium with a thickness of 0.1 mm was used, just like in Example 1, and the flow channel period of the target separator plate to be formed was 1.18 mm and the flow channel depth was 0.38 mm. Although a crack-free titanium separator plate can be manufactured using conventional multi-stage press forming, the dimensional accuracy of the flow channels was low.

[0100] Using the novel method provided in the present invention, a pre-formed titanium separator was first subjected to a single electrical treatment. The electrical treatment time was set to 2 seconds, ensuring that the maximum temperature of the flow path area reached 730°C when the titanium separator was de-energized after being electrically treated for 2 seconds. At this time, the output voltage of the power box obtained through correction was 190 V, the duty cycle was 100%, and the pulse frequency was 4000 Hz. The flow path depth of the titanium separator formed by the novel method according to the present invention is approximately 10 μm higher than that of a titanium separator formed by a multi-stage cold press, and the cross-section of the formed flow path is closer to the design value. This demonstrates that the novel method according to the present invention can also be used as an effective means to improve the dimensional accuracy of the flow path of a target metal separator.

[0101] Example 3

[0102] In this embodiment, the specimen substrate was selected as TA1 industrial pure titanium with a thickness of 0.1 mm and a titanium element content higher than 99.5%, produced at a certain steel mill, and the goal was to improve the fracture elongation of the titanium plate.

[0103] Using the novel method provided in the present invention, a titanium plate was pre-tensioned to a 15% elongation and then subjected to an electric treatment for 10 seconds, ensuring that the maximum temperature reached 550°C upon interruption after 10 seconds of electric treatment. Finally, a load was applied again to tension the plate until fracture occurred. As a result of the tensile test, the elongation of the titanium plate was improved by approximately 23% compared to the room temperature tensile condition.

[0104] Example 4

[0105] In this embodiment, the specimen substrate was selected as 446 ferritic stainless steel with a thickness of 0.1 mm produced at a domestic steel mill in China, and the possibility of applying the novel method proposed in the present invention to an ultra-thin stainless steel substrate based on uniaxial tensile was explored.

[0106] Using the novel method provided in the present invention, a ferritic stainless steel sheet was pre-tensioned to an elongation of 15%, followed by an electric treatment for 2 seconds. After the 2 seconds of electric treatment, the maximum temperature was ensured to be 1000℃ upon disengagement, and finally, a load was applied again to tension the sheet until fracture. As a result of the tensile test, the elongation of the ferritic stainless steel was improved by approximately 32% compared to the room temperature tensile condition, which demonstrated that the novel method according to the present invention can improve the formability of ferritic stainless steel.

[0107] All numerical values ​​cited in this document include all values ​​of lower and upper values ​​that increase by one unit between the lower and upper limits, provided that there is at least a two-unit interval between any lower value and any value higher than it. For example, if the value of a quantity of a part or a process variable (e.g., temperature, pressure, time, etc.) is stated as 1 to 90, preferably 20 to 80, more preferably 30 to 70, the purpose is to explain that values ​​such as 15 to 85, 22 to 68, 43 to 51, 30 to 32 are also clearly listed in this specification. For values ​​less than 1, one unit is appropriately considered to be 0.0001, 0.001, 0.01, or 0.1. These are merely examples intended for clarity, and all possible combinations of numerical values ​​listed between the lowest and highest values ​​can be seen as being clearly described in this specification in a similar manner.

[0108] Unless otherwise noted, all ranges include an endpoint and all numbers between both endpoints. "Approximately" or "approximately" used with a range applies to the two endpoints of that range. Thus, "approximately 20 to 30" is intended to encompass "approximately 20 to approximately 30" and includes at least the specified endpoints.

[0109] It should be understood that the foregoing description is for illustrative purposes only and is not intended to be limiting. By reading the foregoing description, it will be apparent to those skilled in the art that many embodiments and applications other than those provided will be apparent. Accordingly, the scope of this teaching should not be determined by reference to the foregoing description, but by reference to the appended claims and the entire scope of the equivalents of such claims. For the sake of completeness, all documents and references, including patent applications and publications, are incorporated by reference into the text. Any omission of any aspect of the subject matter disclosed herein in the foregoing claims is not intended to abandon the subject matter, nor should it be construed that the inventor did not consider such subject matter as part of the disclosed subject matter.

Claims

Claim 1 A feeding process for feeding a metal substrate having a thickness of 0.05 mm or more and 0.2 mm or less into a first press device equipped with a first forming die; a first forming process for forming a pre-formed metal separator plate by performing a first press pre-forming on the metal substrate using the first press device; a transfer electric processing device for moving the pre-formed metal separator plate to an electric processing station of the transfer electric processing device, wherein the clamping area during electric processing is 500 mm 2 A transfer and electro-processing process that performs electro-processing to exceed [amount] and controls the removal of the electro-processed metal separator plate after the electro-processing is completed; a second forming process that performs second press forming on the electro-processed metal separator plate using a second press device to obtain a fully formed metal separator plate; A method for manufacturing a fuel cell metal separator, comprising: a discharge process for discharging the fully formed metal separator from the second press device; wherein the transfer electric processing device comprises an electric processing support platform and a transfer platform located above the electric processing support platform, wherein the electric processing support platform comprises electrode units installed opposite each other, and the electrode units comprise electrode clamps that are operablely pressed and opened, wherein the transfer platform is mounted above the electric processing support platform via a vertical moving support, and the transfer platform is installed to be operable to be movable up and down on the vertical moving support, wherein the transfer platform comprises a rectangular frame and an adsorption pad assembly installed on the rectangular frame to be operable to be movable in one horizontal direction, wherein the adsorption pad assembly is used to adsorb a metal substrate or a metal separator, wherein the adsorption pad assembly has a first horizontal position and a second horizontal position in one horizontal direction relative to the rectangular frame, and wherein the transfer platform has a first height position and a second height position located above the first height position on the vertical moving support. Claim 2 A method for manufacturing a fuel cell metal separator according to claim 1, wherein at least one intermediate forming process for performing press forming on the metal separator is additionally included between the first forming process and the second forming process, and the electrical treatment process is provided between both forming processes. Claim 3 delete Claim 4 A method for manufacturing a fuel cell metal separator according to claim 1, wherein, during the transfer and electro-processing process, the adsorption pad assembly is controlled to adsorb a pre-formed metal separator at the second horizontal position and the second height position, then the electrode clamp is opened, the adsorption pad assembly is controlled to descend to the first height position and then move from the second horizontal position to the first horizontal position, then the pre-formed metal separator is transferred between the electrode clamps, and the adsorption pad assembly is controlled to release the pre-formed metal separator while the electrode clamp is controlled to press the pre-formed metal separator to perform electro-processing, and finally the electrode clamp is opened and the adsorption pad assembly is controlled again to adsorb the electro-processed metal separator and move from the first horizontal position to the second horizontal position, and then the electro-processed metal is moved upward to the second height position. Claim 5 A method for manufacturing a fuel cell metal separator according to claim 1, wherein, during the input process, a manipulator feeds a metal substrate into the first press device and controls the pre-formed metal separator to be removed from the first press device after the first forming process is completed, and after the transfer and electro-processing process is completed, the electro-processed metal separator is also transferred to the second press device through the manipulator, and during the removal process, the manipulator controls the fully formed metal separator to be removed from the second press device. Claim 6 A method for manufacturing a fuel cell metal separator according to claim 1, further comprising an electrical processing parameter acquisition process for acquiring an electrical processing parameter such that the maximum temperature of the pre-formed metal separator becomes 500 to 1200℃ when the electrical processing time ends and the current is cut off, and the electrical processing time is 0.5 to 10 seconds. Claim 7 A method for manufacturing a fuel cell metal separator according to claim 1, characterized by monitoring the temperature of a pre-formed metal separator under electrical processing conditions using an infrared thermal imaging camera. Claim 8 A method for manufacturing a fuel cell metal separator according to claim 1, wherein the electrical treatment uses a constant voltage DC current or a pulse DC current, wherein the output voltage amplitude is 0 to 300 V, the duty ratio is 0 to 100%, and the frequency is 100 Hz to 4000 Hz. Claim 9 A method for manufacturing a fuel cell metal separator according to claim 1, wherein the electric processing support platform is provided with a first electric guide rail, the electrode clamp comprises a lower electrode with both ends fixedly connected to the first electric guide rail and an upper electrode with both ends movably connected to the electric guide rail, the first electric guide rail is movable so that the upper electrode moves up and down to open and close the electrode clamp, the transfer platform comprises an electric extendable guide rail installed on the lower side of a rectangular frame, the adsorption pad assembly is connected between two electric extendable guide rails and is driven to switch between a first horizontal position and a second horizontal position, the vertical movement support comprises two second electric guide rails installed vertically on the electric processing support platform, and the rectangular frame is vertically connected to two second electric guide rails and is driven to switch between a first height position and a second height position. Claim 10 delete

Images