A secondary groove electrolytic broaching apparatus and method for enhancing heat transfer with air-cooled plates

Abstract

This invention discloses an electrolytic broaching device and method for secondary grooves in air-cooled electrode plates for enhanced heat exchange, relating to the field of electrolytic machining technology. The device includes a cathode mounted on a machine tool spindle, with a machining section corresponding to the airflow channel of the air-cooled electrode plate. A secondary cathode blade is fixedly mounted on the side and bottom walls of the machining section. A positive terminal of a power supply is connected to the air-cooled electrode plate, and a negative terminal is connected to the cathode. After power is applied, electrolyte is introduced into the airflow channel. The machine tool spindle drives the cathode into the airflow channel and electrolytically broaches at the contact point with the secondary cathode blade, forming a secondary groove. Based on the aforementioned electrolytic broaching device and method for secondary grooves in air-cooled electrode plates for enhanced heat exchange, this invention connects the secondary cathode blade to the cathode, the air-cooled electrode plate to the anode, and electrolyte to the airflow channel. Employing electrolytic broaching, it achieves one-time machining of the secondary grooves in the airflow channel of the air-cooled electrode plate.

Description

Technical Field

[0001] This invention relates to the field of electrolytic machining technology, and in particular to a secondary groove electrolytic broaching apparatus and method for enhancing heat exchange of air-cooled electrode plates. Background Technology

[0002] A fuel cell is an electrochemical device that directly converts the chemical energy of fuel into electrical energy. Its working principle is based on an electrochemical reaction, unlike traditional internal combustion engines which generate power through combustion. Fuel cells produce almost no pollutants during operation, emitting only water and heat, thus being considered a clean and efficient energy conversion technology. One of the core components of a fuel cell is the bipolar plate, whose functions include current transmission, gas distribution, and heat dissipation.

[0003] Currently, there are three main types of bipolar plates: graphite bipolar plates, graphite-polymer composite plates, and metal bipolar plates. Among them, metal bipolar plates have good operating performance, high density, good electrical and thermal conductivity, and are lightweight, making them particularly suitable for applications such as drones.

[0004] Air-cooled fuel cells use air for cooling, therefore their metal bipolar plates are air-cooled plates with rectangular airflow channels. However, the traditional rectangular airflow channels of air-cooled plates are insufficient to meet the heat dissipation requirements of fuel cells. For air-cooled plates, secondary groove structures are created within the airflow channels to enhance heat exchange, further strengthening heat dissipation and improving fuel cell performance. However, such structures pose significant challenges to traditional machining methods such as hydraulics and milling. The manufacturing processes for air-cooled plates mainly include hydraulics, stamping, milling, and laser processing. These processes, when machining the secondary groove structures of air-cooled plates, not only easily cause residual stress but also have low processing efficiency, cause tool wear, and high processing costs, making them unsuitable or even difficult to implement in manufacturing air-cooled plates with secondary groove structures. Summary of the Invention

[0005] The purpose of this invention is to provide a secondary groove electrolytic broaching device and method for enhancing heat exchange in air-cooled plates, so as to solve the problems existing in the prior art. The secondary cathode is connected to the cathode, the air-cooled plate is connected to the anode, and the electrolyte is introduced into the air flow channel. Electrolytic broaching is used to realize the one-time processing of the secondary grooves in the air flow channel of the air-cooled plate.

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

[0007] This invention provides a secondary groove electrolytic drawing device for enhancing heat exchange with air-cooled plates, comprising:

[0008] The cathode is mounted on the machine tool spindle and has a machining section that corresponds to the airflow channel of the air-cooled electrode plate.

[0009] The secondary cathode blade is fixedly disposed on the side wall and bottom wall of the processing part;

[0010] The power supply has a positive terminal for connecting to the air-cooled electrode plate and a negative terminal for connecting to the cathode. After the power is turned on, electrolyte is introduced into the air flow channel. The machine tool spindle can drive the cathode into the air flow channel and electrolytically broach at the contact position with the secondary cathode blade to form secondary grooves. There are multiple secondary grooves at the bottom and sidewalls of the air flow channel in the air-cooled electrode plate. The secondary grooves have the beneficial effects of increasing air flow and destroying the thermal boundary layer to enhance the heat transfer of the air-cooled electrode plate.

[0011] Optionally, the cathode portion includes a rectangular block made of metal, and a plurality of processing parts are fixedly provided at the bottom of the rectangular block. The number of processing parts is the same as the number of air channels of the air-cooled electrode plate, and they are arranged in a one-to-one correspondence.

[0012] Optionally, the cathode portion and the machining portion are integrally formed.

[0013] Optionally, the cross-sectional shape of the processing part is the same as the cross-sectional shape of the air flow channel, and after the processing part enters the air flow channel axially, there is a gap between the outer wall of the processing part and the inner wall of the air flow channel.

[0014] Optionally, the secondary cathode blade gradually tilts outward from one end near the air-cooled electrode plate to the other end, giving it a certain tilt angle. During processing, the depth of the secondary groove is gradually processed to a specified depth. This design can improve the feed rate and increase processing efficiency and accuracy.

[0015] Optionally, the end face of the secondary cathode blade away from the processing part is the working surface, and the non-working surface of the secondary cathode blade, the cathode part, and the processing part are all coated with an insulating layer to shield stray corrosion.

[0016] Optionally, the cross-section of the secondary cathode blade can be rectangular, trapezoidal, circular, or triangular, and its specific structural shape is not fixed and can be varied according to the required shape of the secondary trench.

[0017] This invention also provides a secondary groove electrolytic broaching method for enhancing heat exchange with air-cooled electrode plates, wherein the air-cooled electrode plates are fixed and clamped by tooling, and the cathode portion is connected to the machine tool spindle, comprising the following steps:

[0018] Step 1: Design the secondary cathode blade. First, based on the shape, width, and depth of the secondary groove, determine the shape and dimensions of the machining surface of the secondary cathode blade, including parameters such as the depth, width, and tilt angle of the secondary cathode blade.

[0019] Step 2, tool setting: feed the machining part forward until the front end face of the machining part is exactly coplanar with the end face of the air-cooled electrode plate. The tool setting is completed, so that a certain machining gap is reserved between the machining part and the air-cooled electrode plate.

[0020] Step 3: Secondary groove electrolytic broaching of the airflow channel. Connect the air-cooled electrode plate to the positive terminal of the power supply and the secondary cathode blade to the negative terminal of the power supply. Set the electrolytic machining parameters and introduce the electrolyte. Set the machine tool spindle feed speed and drive the cathode part to move, so that it drives the machining part and the secondary cathode blade to gradually cut into the airflow channel. Dissolution occurs at the contact position between the side wall of the airflow channel and the working surface of the secondary cathode blade. The electrolyte carries away the electrolytic products and Joule heat.

[0021] Step four, retract the tool. When the machining part is completely cut out from the air flow channel, the secondary grooves are all machined. Power is cut off and the electrolyte supply is stopped. The machining part returns to the initial position along the original path and then replaces the next air-cooled electrode plate to be machined.

[0022] The present invention achieves the following technical effects compared to the prior art:

[0023] This invention manufactures secondary grooves with enhanced heat exchange function within the airflow channels of air-cooled plates by setting secondary cathode blades at the bottom and sides of the machining section and using an electrolytic broaching method. All secondary grooves in the airflow channels can be manufactured in a single electrolytic broaching process, with no wear on the secondary cathode blades, fully leveraging the advantages of high efficiency and low cost in electrolytic machining. The electrolytic broaching method of this invention can adapt to machining secondary grooves of various shapes by changing the structure of different secondary cathode blades. This electrolytic broaching method can also be applied to the manufacture of other channels with through-grooves, such as plate heat exchangers, demonstrating strong process applicability. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a schematic diagram of the secondary groove electrolytic broaching device for enhancing heat exchange with air-cooled plates according to the present invention.

[0026] Figure 2 for Figure 1 Enlarged view of a specific area;

[0027] Figure 3 This is a cross-sectional view of the process of the secondary groove electrolytic drawing method for enhancing heat exchange with air-cooled plates according to the present invention;

[0028] Figure 4 A schematic diagram of the inverted trapezoidal secondary trench and the corresponding secondary cathode blade structure;

[0029] Figure 5 A schematic diagram of a secondary trench with an arc-shaped structure and its corresponding secondary cathode blade structure;

[0030] Figure 6 This is a schematic diagram of a triangular secondary trench and its corresponding secondary cathode blade structure.

[0031] Explanation of reference numerals in the attached drawings: 1-Cathode section, 2-Air-cooled electrode plate, 3-Processing section, 4-Air flow channel, 401-Air flow channel in the cutting stage, 402-Air flow channel in the intermediate stage, 403-Air flow channel in the cutting-out stage, 5-Secondary cathode blade, 6-Secondary trench, 7-Electrolyte. Detailed Implementation

[0032] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0033] The purpose of this invention is to provide a secondary groove electrolytic broaching device and method for enhancing heat exchange in air-cooled plates, so as to solve the problems existing in the prior art. The secondary cathode is connected to the cathode, the air-cooled plate is connected to the anode, and the electrolyte is introduced into the air flow channel. Electrolytic broaching is used to realize the one-time processing of the secondary grooves in the air flow channel of the air-cooled plate.

[0034] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0035] Electrolytic machining (EMC) removes material based on the principle of anodic electrochemical dissolution of metal materials. It offers advantages such as zero tool cathode wear, high processing efficiency, no limitations on material hardness, no residual stress, and good surface finish, making it particularly advantageous for machining air-cooled metal bipolar plates. For air-cooled bipolar plates, the secondary groove structure on the inner wall of the airflow channels further enhances heat dissipation and improves fuel cell performance. EMC can be used to manufacture these plates. Based on this, this invention designs an electrolytic broaching scheme that can perform secondary groove machining on all airflow channels in the air-cooled bipolar plate in a single operation. This method can manufacture secondary grooves with enhanced heat exchange capabilities. The electrolytic broaching method of this invention is simple to implement, allows for reusable tool cathodes, has low processing costs, and high efficiency, making it of great significance for the manufacture of such bipolar plate structures.

[0036] like Figure 1 and Figure 2As shown in the figure, the direction of the solid black arrow indicates the feed direction. This invention provides a secondary groove electrolytic broaching device for enhancing heat exchange of air-cooled electrode plates, including a cathode part 1, which is mounted on the machine tool spindle. Multiple metal machining parts 3 are integrally formed at the bottom of the cathode part 1, and the machining parts 3 are correspondingly arranged with the air flow channels 4 of the air-cooled electrode plate 2. Secondary cathode blades 5 are fixedly mounted on the side and bottom walls of the machining parts 3. The secondary cathode blades 5 are outwardly convex strip-shaped ridge structures used to connect to the power supply cathode to achieve the machining of the secondary grooves 6. The positive terminal of the power supply is used to connect to the air-cooled electrode plate 2, and the negative terminal is used to connect to the... The cathode part 1 is connected and communicates with the working surface of the secondary cathode blade 5. After the power is turned on, the electrolyte 7 is introduced into the air flow channel 4. The electrolyte 7 is existing technology, so it will not be described in detail. The machine tool spindle can drive the cathode part 1 to move, thereby driving the machining part 3 into the air flow channel 4, and electrolytically broaching at the contact position with the working surface of the secondary cathode blade 5 to form secondary grooves 6. There are multiple secondary grooves 6 at the bottom and side walls of the air flow channel 4 of the air-cooled plate 2. The secondary grooves 6 have the beneficial effects of increasing air flow and destroying the thermal boundary layer to enhance the heat transfer of the air-cooled plate.

[0037] Combination Figure 3 As shown, the secondary groove electrolytic drawing method for enhancing heat transfer with air-cooled plates according to the present invention includes the following steps:

[0038] Step 1: Design the secondary cathode blade 5. First, based on the shape, width, and depth of the secondary groove 6, determine the shape and dimensions of the machining surface of the secondary cathode blade 5, including parameters such as the depth, width, and tilt angle of the secondary cathode blade 5.

[0039] Step 2: Tool setting. Feed the machining section 3 forward until the end face of the secondary cathode blade 5 is exactly coplanar with the end face of the air flow channel 4. Tool setting is then complete, leaving a certain machining gap between the secondary cathode blade 5 and the bottom of the air flow channel 4.

[0040] Step 3: Connect the air-cooled electrode plate 2 to the positive terminal of the power supply, and the cathode part 1 to the negative terminal of the power supply. Set the electrolytic machining parameters and introduce the electrolyte 7. Set a certain feed speed for the spindle to move the cathode part 1 forward, causing the machining part 3 to gradually cut into the corresponding airflow channel 4. Since the machining part 3 is coated with an insulating layer, and the non-working surface of the secondary cathode blade 5 is also coated with an insulating layer, the air-cooled electrode plate undergoes local dissolution at the small gap in contact with the working surface of the secondary cathode blade 5. The high-speed flowing electrolyte 7 carries away the electrolysis products and Joule heat.

[0041] Step 4: Retract the tool. When the machining section 3 has completely cut out from the airflow channel 4 of the air-cooled electrode plate 2, the secondary groove 6 is completely machined. Power is cut off and the liquid flow is stopped. The machining section 3 returns along the original path until the entire workpiece is visible, and then replaces the next air-cooled electrode plate 2 to be machined.

[0042] To observe its structure more clearly, combined with Figure 2 As shown, the bottom and sides of the machining section 3 have secondary cathode blades 5. The secondary cathode blades 5 gradually slope away from the machining section 3 from the front end to the rear end, that is, their height gradually increases from the front end to the rear end, giving them a certain tilt angle. During machining, the depth of the secondary grooves 6 is gradually machined to the specified depth. This design can improve the feed rate and improve machining efficiency and accuracy. The bottom surface of the secondary cathode blades 5 is the machining surface, and the remaining parts should be coated with an insulating layer to shield the non-machining areas from electric field corrosion.

[0043] Combination Figure 3 As shown, secondary groove electrolytic broaching is divided into three stages, such as... Figure 3 As shown, the first stage is the cutting-in stage. At this time, the front end of the processing part 3 has just cut into the air flow channel 4 of the air-cooled electrode plate 2, forming the air flow channel 401 of the cutting-in stage. Due to electrochemical dissolution, a processing gap is formed between the air flow channel 4 of the air-cooled electrode plate 2 and the secondary cathode blade 5. The electrolyte flows through the gap, and the processing continues. The front end of the air flow channel 4 of the air-cooled electrode plate 2 gradually forms a secondary groove 6 along the direction of the secondary cathode blade 5. In the middle stage, the secondary cathode blade 5 is fully inserted, and the first half of the secondary groove 6 of the air flow channel 4 of the air-cooled electrode plate 2 has been formed. At this time, the air flow channel 402 of the middle stage is formed. Finally, in the cutting-out stage, the structure of all the secondary grooves 6 of the air flow channel 4 of the air-cooled electrode plate 2 is basically formed until the secondary cathode blade 5 completely leaves the air flow channel 4 of the air-cooled electrode plate 2. The processing ends, and the air flow channel 403 of the cutting-out stage is formed.

[0044] Combination Figure 4 , Figure 5 and Figure 6 The diagram shows different secondary trench 6 structures and their corresponding secondary cathode blades 5. From the perspective of enhancing heat transfer, the shape of the secondary trench 6 affects the heat dissipation performance of the air-cooled fuel cell. For air-cooled plates 2 with different required secondary trench 6 shapes, electrolytic broaching can be used to process them by adjusting the structural form of the secondary cathode blades 5. Figure 4 The diagram shows an inverted trapezoidal secondary trench 6. The corresponding secondary cathode blade 5 structure reduces the width of the front end, thus achieving an inverted trapezoidal secondary trench that is narrower at the top and wider at the bottom. Similarly, Figure 5 The secondary trench 6 is an arc-shaped structure, and the corresponding secondary cathode blade 5 has an arc-shaped cross-section. Figure 6 The secondary groove 6 is triangular, and its corresponding secondary cathode blade 5 has a wider front end and a narrower rear end. Using the electrolytic broaching method of this invention, various shapes of the secondary groove 6 can be machined by adjusting the shape of the secondary cathode blade 5.

[0045] Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this invention. Furthermore, those skilled in the art will recognize that, based on the ideas of this invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this invention.

Claims

1. A secondary groove electrolytic broaching device for enhancing heat exchange with air-cooled plates, characterized in that: include: The cathode is mounted on the machine tool spindle and has a machining section that corresponds to the airflow channel of the air-cooled electrode plate. The secondary cathode blade is fixedly disposed on the side wall and bottom wall of the processing part, and the secondary cathode blade gradually tilts outward from one end near the air-cooled electrode plate to the other end. The power supply has a positive terminal for connecting to the air-cooled plate and a negative terminal for connecting to the cathode. After the power supply is turned on, electrolyte is introduced into the air channel. The machine tool spindle can drive the cathode into the air channel and electrolytically broach at the contact position with the secondary cathode blade to form a secondary groove. The cross-sectional shape of the processing part is the same as that of the air flow channel, and after the processing part enters the air flow channel axially, there is a gap between the outer wall of the processing part and the inner wall of the air flow channel.

2. The secondary groove electrolytic broaching device for enhancing heat exchange with air-cooled electrode plates according to claim 1, characterized in that: The cathode portion includes a rectangular block made of metal. Multiple processing sections are fixedly provided at the bottom of the rectangular block. The number of processing sections is the same as the number of air channels of the air-cooled electrode plate, and they are arranged in a one-to-one correspondence.

3. The secondary groove electrolytic broaching device for enhancing heat exchange with air-cooled electrode plates according to claim 1, characterized in that: The cathode section and the machining section are integrally formed.

4. The secondary groove electrolytic broaching device for enhancing heat exchange with air-cooled electrode plates according to claim 1, characterized in that: The end face of the secondary cathode blade away from the processing part is the working surface, and the non-working surface of the secondary cathode blade, the cathode part, and the processing part are all coated with an insulating layer.

5. The secondary groove electrolytic broaching device for enhancing heat exchange with air-cooled electrode plates according to claim 1, characterized in that: The cross-section of the secondary cathode blade is rectangular, trapezoidal, circular, or triangular.

6. A method for secondary groove electrolytic broaching of air-cooled electrode plates for enhanced heat transfer based on the secondary groove electrolytic broaching apparatus for enhanced heat transfer of air-cooled electrode plates according to any one of claims 1 to 5, characterized in that: Includes the following steps: Step 1: Design the secondary cathode blade. First, determine the shape and dimensions of the machining surface of the secondary cathode blade based on the shape, width, and depth of the secondary groove. Step 2, tool setting: feed the machining section forward until the frontmost end face of the machining section is exactly coplanar with the end face of the air-cooled electrode plate. Tool setting is then complete. Step 3: Secondary groove electrolytic broaching of the airflow channel. Connect the air-cooled electrode plate to the positive terminal of the power supply and the secondary cathode blade to the negative terminal of the power supply. Set the electrolytic machining parameters and introduce the electrolyte. Set the machine tool spindle feed speed and drive the cathode part to move, so that it drives the machining part and the secondary cathode blade to gradually cut into the airflow channel. Dissolution occurs at the contact position between the side wall of the airflow channel and the working surface of the secondary cathode blade. The electrolyte carries away the electrolytic products and Joule heat. Step 4: Retract the tool. When the machining section has completely cut out of the air flow channel, the secondary grooves are all machined. Turn off the power and stop the supply of electrolyte. The processing unit returns to its initial position along the original path and then replaces the next air-cooled electrode plate to be processed.

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