阅读说明：本技术 燃料电池双极板加工方法 (Method for processing fuel cell bipolar plate ) 是由 胡尊严 李建秋 徐梁飞 刘慧泽 徐领 *** 于 2019-10-22 设计创作，主要内容包括：本申请涉及一种燃料电池双极板加工方法。所述加工方法根据目标流道结构图,利用激光在所述石墨双极板毛坯上加工流道,得到成型石墨双极板。本申请中激光的光斑直径为微米级。所述加工方法利用激光进行流道加工,激光加工不产生机械应力,光斑直径小,因此激光能加工脊背宽度更窄,排布更紧密的流道。超密流道有利于反应气体的扩散,提高了双极板的性能。进一步的,所述加工方法还包括对所述成型石墨双极板进行表面洁净处理和表面疏水处理,表面疏水处理后的流道不易积水。所述加工方法加工形成的双极板流道的气体输送能力增强,所述加工方法提高了双极板性能。(The application relates to a processing method of fuel cell bipolar plates, which comprises the steps of processing a flow channel on a graphite bipolar plate blank by using laser according to a target flow channel structure diagram to obtain a formed graphite bipolar plate, wherein the spot diameter of the laser is micron-sized, processing the flow channel by using the laser, and generating no mechanical stress and having a small spot diameter, so that the laser can process the flow channel with narrower ridge width and more compact arrangement.)

1, methods for processing bipolar plates of fuel cells, which is characterized by comprising the following steps:

obtaining a graphite bipolar plate blank;

drawing an overall processing path diagram (40) according to the target flow channel structure diagram (30);

machining a flow channel on the surface of the graphite bipolar plate blank by using laser according to the integral machining path diagram (40) to obtain a formed graphite bipolar plate;

and carrying out surface cleaning treatment and surface hydrophobic treatment on the formed graphite bipolar plate.

2. The fuel cell bipolar plate processing method of claim 1, wherein the step of processing a blank of a graphite bipolar plate comprises:

processing to form a hard bipolar plate original blank;

and forming an inlet and an outlet and common flow passage air holes on the surface of the original blank of the hard bipolar plate by adopting a machining machine tool so as to form the blank of the graphite bipolar plate.

3. The method of processing a fuel cell bipolar plate according to claim 1, wherein the step of plotting the overall process path map (40) based on the target flow channel configuration map (30) comprises:

acquiring the flow channel width, the flow channel depth, the flow channel extension shape and the flow channel interval of a target flow channel (300) according to the target flow channel structure diagram (30);

selecting the spot diameter and the light traveling distance of the laser according to the width of the flow channel;

selecting scanning frequency, light traveling speed and scanning times according to the depth of the flow channel;

and obtaining the integral processing path diagram (40) according to the flow channel extension shape, the flow channel interval, the light spot diameter and the light transmission interval.

4. The method of processing a fuel cell bipolar plate according to claim 3, wherein the step of obtaining the overall processing path diagram (40) based on the flow channel extension shape, the flow channel pitch, the spot diameter, and the step of running light pitch comprises:

the target runner structure diagram (30) includes a plurality of target runners (300), the overall processing path diagram (40) includes a plurality of scanning line groups (400), the plurality of scanning line groups (400) are arranged corresponding to the plurality of target runners (300) , each scanning line group (400) includes a plurality of scanning lines, and the shapes of the scanning lines corresponding to the target runners (300) are obtained according to the runner extension shapes;

calculating the light traveling times of each target flow channel (300) according to the diameter of the light spot and the light traveling distance, obtaining the number of the scanning lines according to the light traveling times, obtaining the scanning line distance of two corresponding adjacent scanning lines according to the light traveling distance, wherein the two adjacent scanning lines are positioned in scanning line groups (400);

obtaining the scanning group spacing of two corresponding adjacent scanning line groups (400) according to the runner spacing;

and obtaining the whole processing path diagram (40) according to the shape of the scanning lines, the number of the scanning lines, the scanning line interval and the scanning group interval.

5. The method of processing a fuel cell bipolar plate according to claim 3, wherein before the step of selecting the scanning frequency, the light traveling speed, and the number of scans according to the depth of the flow channels, the method further comprises:

and carrying out a pre-scanning experiment to determine the scanning frequency, the light walking speed and the processing scanning times.

6. The method of processing a fuel cell bipolar plate according to claim 5, wherein the step of performing a pre-scan experiment to determine the scan frequency, the walking speed, and the number of processing scans comprises:

obtaining an experimental graphite bipolar plate blank, wherein the experimental graphite bipolar plate blank is the same as the graphite bipolar plate blank to be processed;

th linear scanning is carried out on the experimental graphite bipolar plate blank by adopting the scanning frequency and the light traveling speed, the th experimental scanning time is N, a th groove is obtained, the depth of the th groove is measured, and the th depth is obtained;

performing second linear scanning on the blank of the experimental graphite bipolar plate by adopting the scanning frequency and the light traveling speed, wherein the second experimental scanning frequency is M, so as to obtain a second groove, measuring the depth of the second groove, and obtaining a second depth, wherein M is greater than N, and M and N are positive integers;

determining the number of machining scans according to the th depth, the second depth, M, N and the runner depth.

7. The method of processing a fuel cell bipolar plate according to claim 6, wherein the number of processing scans is determined using a differential method according to the th depth, the second depth, M, N and the channel depth.

8. The method of processing a fuel cell bipolar plate according to claim 1, wherein a high-energy laser is used to process flow channels on the surface of the graphite bipolar plate blank according to the overall processing path diagram (40) to obtain a formed graphite bipolar plate.

9. The method of processing a fuel cell bipolar plate according to claim 4, wherein the step of obtaining the shape of the scan line corresponding to the objective flow channel (300) from the extended shape of the objective flow channel (300) further comprises:

judging whether the target flow channel (300) comprises a corner structure or not;

if yes, the scanning line corresponding to the corner structure is an arc-shaped chamfer structure (402).

10. The method of processing a fuel cell bipolar plate according to claim 4, wherein the plurality of target flow channels (300) includes th target flow channel (310) and a second target flow channel (320), the plurality of scan line groups (400) includes th scan line group (410) and a second scan line group (420), the th scan line group (410) includes a plurality of th scan lines (411), the th scan line (411) corresponds to the th target flow channel (310), the second scan line group (420) includes a plurality of second scan lines (421), the second scan lines (421) correspond to the second target flow channel (320), and the step of obtaining the shape of the scan lines corresponding to the target flow channel (300) according to the extended shape of the target flow channel (300) further includes:

determining whether the th target runner (310) start point overlaps with the extended path of the second target runner (320);

if yes, a machining allowance gap is set at the starting point of the th scanning line (411).

11. The fuel cell bipolar plate processing method of claim 1, wherein the step of processing a blank of a graphite bipolar plate comprises:

and forming the graphite bipolar plate blank by adopting graphite powder die pressing, wherein the surface of the graphite bipolar plate blank is provided with an inlet and an outlet, a common flow passage air hole and a main flow passage.

Technical Field

The application relates to the technical field of fuel cells, in particular to a processing method of fuel cell bipolar plates.

Background

The bipolar plate is a core part of the fuel cell, and the design of the bipolar plate is a core factor determining the performance of the fuel cell. The surface of the bipolar plate is provided with a cathode runner, an anode runner, a cooling runner and other structures. The flow channel structure performs functions such as distribution of reaction gas, gas cooling, water discharge, and the like in the fuel cell.

Disclosure of Invention

Based on this, it is necessary to provide methods for processing a bipolar plate for a fuel cell, in order to solve the problem of how to improve the performance of the bipolar plate.

A method for processing bipolar plate of fuel cell, comprising:

a graphite bipolar plate blank is provided.

And drawing an integral processing path diagram according to the target flow channel structure diagram.

And processing a flow channel on the surface of the graphite bipolar plate blank by using laser according to the integral processing path diagram to obtain the formed graphite bipolar plate.

And carrying out surface cleaning treatment and surface hydrophobic treatment on the formed graphite bipolar plate.

In embodiments, the step of processing the graphite bipolar plate blank comprises:

and processing to form the original blank of the hard bipolar plate.

And forming an inlet and an outlet and common flow passage air holes on the surface of the original blank of the hard bipolar plate by adopting a machining machine tool so as to form the blank of the graphite bipolar plate.

In embodiments, the step of drawing the overall process path map according to the target runner structure map includes:

and acquiring the width, the depth, the extension shape and the interval of the target flow channel according to the structure diagram of the target flow channel.

And selecting the spot diameter and the light traveling distance of the laser according to the width of the flow channel.

And selecting scanning frequency, light traveling speed and processing scanning times according to the depth of the flow channel.

And obtaining the integral processing path diagram according to the flow channel extension shape, the flow channel interval, the light spot diameter and the light walking interval.

In embodiments, the step of obtaining the overall processing path diagram according to the flow channel extension shape, the flow channel pitch, the spot diameter, and the light traveling pitch includes:

the target flow path structure diagram includes a plurality of target flow paths, the overall processing path diagram includes a plurality of scanning line groups, the plurality of scanning line groups are arranged corresponding to the plurality of target flow paths , each scanning line group includes a plurality of scanning lines, and the shapes of the scanning lines corresponding to the target flow paths are obtained according to the flow path extension shapes.

And calculating the light traveling times of each target flow channel according to the diameter of the light spot, the light traveling interval and the width of the flow channel, obtaining the number of the scanning lines according to the light traveling times, and obtaining the scanning line interval of two corresponding adjacent scanning lines according to the light traveling interval, wherein the two adjacent scanning lines are positioned in scanning line groups.

And obtaining the scanning group interval of two corresponding adjacent scanning line groups according to the runner interval.

And obtaining the integral processing path diagram according to the shape of the scanning lines, the number of the scanning lines, the scanning line spacing and the scanning group spacing.

In embodiments, before the step of selecting the scanning frequency, the light traveling speed, and the scanning times according to the depth of the flow channel, the processing method further includes:

and carrying out a pre-scanning experiment to determine the scanning frequency, the light walking speed and the processing scanning times.

In embodiments, the step of performing a pre-scan experiment to determine the scan frequency, the walking speed, and the number of process scans comprises:

and obtaining an experimental graphite bipolar plate blank, wherein the experimental graphite bipolar plate blank is made of the same material as the graphite bipolar plate blank to be processed.

And (3) carrying out th linear scanning on the experimental graphite bipolar plate blank by adopting the scanning frequency and the light walking speed, wherein the th experimental processing scanning time is N, obtaining a th groove, measuring the depth of the th groove, and obtaining the th depth.

And performing second linear scanning on the experimental graphite bipolar plate blank by adopting the scanning frequency and the light traveling speed, wherein the scanning frequency of the second experimental processing is M, so as to obtain a second groove, measuring the depth of the second groove, and obtaining a second depth, wherein M is greater than N, and M and N are positive integers.

Determining the number of machining scans according to the th depth, the second depth, M, N and the runner depth.

In embodiments, the processing scanning times are determined by a difference method according to the th depth, the second depth, M, N and the flow channel depth.

In examples, the high-energy laser was used to machine flow channels on the surface of the graphite bipolar plate blank according to the overall machining path map, resulting in a formed graphite bipolar plate.

In embodiments, the step of obtaining the shape of the scan line corresponding to the target flow path according to the extended shape of the target flow path further includes:

and judging whether the target flow channel comprises a corner structure.

If yes, the scanning line corresponding to the corner structure is of an arc-shaped chamfer structure.

In embodiments, the multiple target runners include a th target runner and a second target runner, the multiple scan line groups include an th scan line group and a second scan line group, the th scan line group includes multiple th scan lines, the th scan line corresponds to the th target runner, the second scan line group includes multiple second scan lines, the second scan lines correspond to the second target runner, and the step of obtaining the shapes of the scan lines corresponding to the target runners according to the extended shape of the target runners further includes:

and judging whether the th target flow channel starting point is overlapped with the extending path of the second target flow channel.

If yes, a machining allowance gap is set at the th scanning line starting point.

In embodiments, the step of processing the graphite bipolar plate blank comprises:

and forming the graphite bipolar plate blank by adopting graphite powder die pressing, wherein the surface of the graphite bipolar plate blank is provided with an inlet and an outlet, a common flow passage air hole and a main flow passage.

The processing method comprises the steps of obtaining a graphite bipolar plate blank, processing a flow channel on the graphite bipolar plate blank by utilizing laser according to a target flow channel structure diagram to obtain a formed graphite bipolar plate, wherein the flow channel ridge processed by a cutter in the prior art is in a millimeter-scale width, and the width of a die forming ridge of die pressing is also in a millimeter-scale, the processing method utilizes laser to process the flow channel, the diameter of a light spot of the laser is in a micron-scale, mechanical stress is not generated, the ridge width can be processed by the laser to be narrower, the flow channel can be more tightly arranged, steps are carried out, the processing method also comprises the steps of carrying out surface cleaning treatment and surface hydrophobic treatment on the formed graphite bipolar plate, the flow channel after the surface hydrophobic treatment is not easy to accumulate water, furthermore, the conveying capacity of the bipolar plate flow channel processed and formed by the processing method is enhanced, and the performance of the bipolar plate is.

Drawings

FIG. 1 is an electrical schematic of the fuel cell bipolar plate processing method provided in the present application in examples;

fig. 2 is a diagram of the structure of the target flow path provided in embodiments of the present application;

FIG. 3 is a diagram of the overall process path provided in examples of the present application;

FIG. 4 is a partial block diagram of the A-A section provided in examples of the present application;

fig. 5 is a schematic structural view of the laser engraving machine provided in embodiments of the present application;

FIG. 6 is a schematic illustration of the position of the refractor provided in the embodiments of the present application;

figure 7 is an image of the bottom of the focusing flow channels of the formed graphite bipolar plate provided in examples of the present application.

Reference numerals:

method 10 for processing bipolar plate of fuel cell

Flow passage 101

Ridge 102

Laser generator 120

Mobile structure 130

Platform 140

Refractor 150

Target flow path structure diagram 30

Target flow path 300

Flow channel spacing H

th target runner 310

Second target flow passage 320

th target runner origin B

Overall processing Path diagram 40

Scan line group 400

Scanning group spacing h1

Scanning line spacing h2

Arc-shaped chamfering structure 402

th scanline group 410

th scan line 411

th scan line start point b

The second scan line group 420

Second scanning line 421

Detailed Description

In order to make the aforementioned objects, features and advantages of the present application more comprehensible, embodiments accompanying the present application are described in detail below with reference to the accompanying drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application. This application is capable of embodiments in many different forms than those described herein and those skilled in the art will be able to make similar modifications without departing from the spirit of the application and it is therefore not intended to be limited to the embodiments disclosed below.

Where in the description of the present application, the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", and the like indicate orientations or positional relationships based on those shown in the drawings, it is to be understood that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", and the like are used for convenience of description and simplicity of description, and do not indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and therefore, are not to be construed as limiting the present application.

In this application, unless expressly stated or limited otherwise, the term "on" or "under" a second feature means that the term directly contacts the second feature or that the term indirectly contacts the second feature through intervening media, further, the term includes that the term is "above", "over" and "above" the second feature, that the term is directly above or obliquely above the second feature, or that only the term is at a higher level than the second feature, that the term includes that the term is "below", "below" and "under" the second feature, that the term is directly below or obliquely below the second feature, or that only the term is at a lower level than the second feature.

The bipolar plate is a core part of the fuel cell, and the design of the bipolar plate is a core factor determining the performance of the fuel cell. The bipolar plate has a cathode flow passage, an anode flow passage, a cooling flow passage and other structures. The bipolar plate performs the functions of distributing, cooling, draining and the like of reaction gas in the fuel cell.

In order to improve the performance of the bipolar plate, technicians continuously narrow the width of the ridge and continuously improve the density, the groove depth and the groove width of the conventional bipolar plate are generally on the level of 1 mm, and part of the processing technology can reach 0.4 mm.

Referring to fig. 1, 2 and 3, an embodiment of the present application provides methods for processing a bipolar plate of a fuel cell, including:

and S100, providing a graphite bipolar plate blank.

S200, drawing the whole processing path diagram 40 according to the target runner structure diagram 30.

And S300, machining a flow channel on the surface of the graphite bipolar plate blank by using laser according to the integral machining path diagram 40 to obtain the formed graphite bipolar plate.

S400, performing surface cleaning treatment and surface hydrophobic treatment on the formed graphite bipolar plate.

The embodiment of the application provides a fuel cell bipolar plate processing method, according to target runner structure chart 30, utilize laser in processing the runner on the graphite bipolar plate blank, obtain the shaping graphite bipolar plate, the runner ridge of cutter processing among the prior art is at millimeter level width, and the mould shaping ridge width of mould pressing is also at millimeter level, processing method utilizes laser to carry out runner processing, and the facula diameter of laser is the micron order in this application, does not produce mechanical stress, and laser can process the ridge width narrowly, arranges tighter runner, it advances steps to advance, processing method still includes to the shaping graphite bipolar plate carries out surface cleaning and surface hydrophobic treatment, and the runner after the surface hydrophobic treatment is difficult for ponding, and then, the transport capacity of the bipolar plate runner that processing method processed and formed strengthens, processing method has improved the bipolar plate performance.

In embodiments, the step S100 includes machining a blank of a hardened bipolar plate by machining an inlet, an outlet, and common flow channel air holes in a surface of the blank of the hardened bipolar plate to form a blank of a graphite bipolar plate.

In another embodiments, the step S100 includes molding graphite powder to form the graphite bipolar plate blank, the surface of which has openings, common channel air holes and main channels, forming the main channels by a molding process, and finely processing the main channels on the surface of the graphite bipolar plate blank by the step S200 to improve the gas diffusion capability of the main channels.

The machining and compression molding method is adopted to machine the air holes of the inlet and outlet common flow passages of the bipolar plate, so that the machining efficiency is improved.

The principle of laser engraving is to use a high-energy laser beam to melt graphite and resin materials in a path swept by a combustion laser to form a runner groove.

In embodiments, the S200 includes:

s210, obtaining a flow channel width, a flow channel depth, a flow channel extending shape and a flow channel interval H of the target flow channel 300 according to the target flow channel structure diagram 30.

S220, selecting the spot diameter and the light transmission distance of the laser according to the width of the flow channel.

And S230, selecting the scanning frequency, the light traveling speed and the processing scanning times according to the depth of the flow channel.

And S240, obtaining the integral processing path diagram 40 according to the flow channel extension shape, the flow channel interval H, the light spot diameter and the light transmission interval.

The flow channel interval H refers to the distance between adjacent side walls between two adjacent flow channels. The light-passing interval refers to the distance between the middle points of two adjacent scanning light spots, wherein the two adjacent scanning light spots are used for processing two adjacent scanning lines.

Please and referring to fig. 4, in embodiments, the S240 comprises:

s241, the target runner structure diagram 30 includes a plurality of target runners 300, the overall processing path diagram 40 includes a plurality of scan line groups 400, the plurality of scan line groups 400 are disposed corresponding to the plurality of target runners 300 , each scan line group 400 includes a plurality of scan lines, and the shapes of the scan lines corresponding to the target runners 300 are obtained according to the runner extension shapes.

S242, calculating the light passing times of each target flow channel 300 according to the spot diameter, the light passing distance, and the flow channel width, obtaining the number of scanning lines according to the light passing times, and obtaining the scanning line distance h2 between two corresponding adjacent scanning lines according to the light passing distance, where the two adjacent scanning lines are located in scanning line groups 400.

And S243, obtaining the scanning group spacing H1 of the two corresponding adjacent scanning line groups 400 according to the flow channel spacing H.

S244, obtaining the overall processing path diagram 40 according to the shape of the scanning lines, the number of the scanning lines, the scanning line pitch h2, and the scanning group pitch h 1.

In S241, scan lines of the scan line group 400 are arranged in parallel, and the shape of the scan line includes a straight line shape, a zigzag line shape, and an arc line shape.

In S242, the light-passing number may be obtained by using a light-passing number formula. The formula of the exposure times is as follows:

n＝(X-Y)/(p+1)

wherein n represents the light-passing times, X represents the flow channel width, Y represents the spot diameter, and p represents the light-passing pitch.

The light-passing distance is selected based on the laser processing characteristics of the graphite bipolar plate blank. The proper light-passing distance can ensure the processing speed and the surface roughness.

In embodiments, a light guide pitch preparation experiment is performed before selecting the light guide pitch, wherein the light guide pitch preparation experiment comprises performing a plurality of laser processing with different light guide pitches and measuring the processing precision of the surface of the flow channel.

In the upper embodiments, the walking pitch is equal to the scanline pitch.

In embodiments, the step S300 is to process a flow channel on the graphite bipolar plate blank by using a laser according to the spot diameter, the scanning frequency, the light traveling speed, the processing scanning times and the overall processing path diagram 40, so as to obtain the formed graphite bipolar plate.

, referring to FIG. 5, in embodiments, the graphite bipolar plate blank is processed by a laser engraving machine, the laser engraving machine comprises an overall control device, a laser generator 120, a platform 140 and a moving structure 130, the laser generator 120 and the moving structure 130 are respectively electrically connected with the overall control device, and the overall control device is used for receiving an external command and controlling the laser generator 120 and the moving structure 130 to work cooperatively according to the external command.

The laser generator 120 is used to generate laser light. The platform 140 is used to hold the graphite bipolar plate blank and provide a tooling platform. The moving structure 130 is fixedly connected to the probe 121 of the laser generator 120, and is configured to drive the laser probe 121 to move according to the overall processing path diagram 40. The moving structure 130 has a spatial three-dimensional moving function.

In embodiments, the step of machining the graphite bipolar plate blank by the laser engraving machine comprises:

and S1, fixing the graphite bipolar plate blank on the platform 140, wherein the graphite bipolar plate blank is marked with a processing origin, and the probe 121 is arranged corresponding to the processing origin of the graphite bipolar plate blank.

And S2, setting the spot diameter, the scanning frequency, the light traveling speed and the processing scanning times on the overall control device.

S3, the overall processing route map 40 is introduced into the overall control device.

And S4, the overall control device controls the laser generator 120 and the moving structure 130 to work cooperatively, and the flow channel processing is carried out on the surface of the graphite bipolar plate blank.

referring to FIG. 6, in embodiments, the laser engraving machine further includes a refractor 150. the refractor 150 is disposed on the laser path for changing the direction of the laser beam.

The method is also used for processing the structures of holes, grooves and combination thereof on the ridges formed between two adjacent target runners 300.

In embodiments, before the step of S230, the processing method further includes:

and S221, performing a pre-scanning experiment to determine the scanning frequency, the light walking speed and the processing scanning times.

Since the proportion of non-graphite parts such as resin in the graphite plate is not , the scanning frequency, the light-passing speed and the processing scanning times need to be completed by the above preliminary experiment.

In embodiments, the S221 includes:

and S11, obtaining an experimental graphite bipolar plate blank, wherein the experimental graphite bipolar plate blank is the same as the graphite bipolar plate blank to be processed.

And S12, performing times of linear scanning on the experimental graphite bipolar plate blank by adopting the scanning frequency and the light traveling speed, wherein the times of experimental processing scanning are N to obtain a th groove, and measuring the depth of the th groove to obtain a th depth.

And S13, performing second linear scanning on the experimental graphite bipolar plate blank by adopting the scanning frequency and the light traveling speed, wherein the second experimental processing scanning time is M, obtaining a second groove, measuring the depth of the second groove, and obtaining a second depth, wherein M is greater than N, and M and N are positive integers.

S14, determining the processing scanning times according to the th depth, the second depth, M, N and the flow channel depth.

In embodiments, in S4, the processing scanning times are determined by a difference method according to the th depth, the second depth, M, N and the channel depth, so as to improve the scanning accuracy.

When the processing requirements of complex structures such as a vertical structure, a plurality of break points, a multi-section processing path, a micro-channel structure with the same size as a light spot and the like exist in the flow channel, a method of changing the light walking speed is adopted, when a linear flow channel is processed, the light walking speed is adopted, when the flow channel with the complex structure is processed, the second light walking speed is adopted, and the light walking speed is higher than the second light walking speed.

In embodiments, a high-energy laser is used in S200 to perform channel processing on the graphite bipolar plate blank, when the high-energy laser is used to process the graphite bipolar plate, the material of the graphite bipolar plate changes to a gasified plasma state, thereby avoiding the accumulation of processing residues and generating processing defects.

The depth of the flow channel processed by the laser corresponds to the volume of graphite which can be melted and burned by emitting the laser in unit time. The flow channel processing is the balance selection of processing speed and precision. The higher the energy, the faster the scan, the faster the machining speed, and the lower the accuracy.

In embodiments, the high energy laser is a picosecond laser, a femtosecond laser, and a nanosecond laser.

The processing method of the fuel cell bipolar plate adopts small spot laser with the level of 10 microns to 200 microns. Since the energy distribution of the laser-engraved spot follows a gaussian distribution, the closer to the center of the laser spot, the higher the energy of the laser. And the small light spots are adopted, so that the energy distribution difference can be reduced, and the processing precision is improved.

In embodiments, a fiber laser is used in the S200 to process the graphite bipolar plate blank in the flow channel way₂The laser has too long wavelength and less energy, and is not suitable for graphite processing. The fiber laser has short wavelength and large energy and is suitable for graphite processing.

In S200, laser light having a wavelength shorter than that of the fiber laser may be used for processing.

In embodiments, in S241, the step of obtaining the shape of the scan line corresponding to the target flow path 300 according to the extended shape of the target flow path 300 further includes:

s21, determining whether the target flow channel 300 includes a corner structure.

S22, if yes, the scan line corresponding to the corner structure is the arc-shaped chamfer structure 402.

In embodiments, the target runner 300 includes a right-angle runner structure, and the right-angle runner structure is designed as the arc-shaped chamfer structure 402, so as to avoid repeated machining at a local position and improve the machining precision.

In embodiments, the multiple target runners 300 include a th target runner 310 and a second target runner 320, the multiple scan line groups 400 include an th scan line group 410 and a second scan line group 420, the th scan line group 410 includes multiple th scan lines 411, the th scan line 411 corresponds to the th target runner 310, the second scan line group 420 includes multiple second scan lines 421, the second scan lines 421 correspond to the second target runner 320, and in S241, according to the extended shape of the target runner 300, the step of obtaining the shape of the scan lines corresponding to the target runner 300 further includes:

s31, it is determined whether the th target runner starting point B overlaps with the extended path of the second target runner 320.

And S32, if yes, setting a machining allowance gap at the th scanning line starting point b.

If the th scanning line 411 is overlapped with the second scanning line 421, the laser scans twice at the overlapped part, and the processing depth of the overlapped part is larger than that of other parts, the processing allowance gap is set, namely constant gap is set from the second scanning line 421 at the th scanning line starting point b, so as to ensure that the center of the facula can not repeatedly scan the gap position, and the processing precision is improved, and the length of the gap and the radius of the facula are in the same order of .

Please and referring to fig. 7, in examples, the experiment used a common expanded graphite plate and an 80W picosecond laser, and the fixed traveling speed was 1m/s, and the flow channel depth was about 0.2mm by scanning 100 times with 50% energy in the preliminary experiment, and about 0.75mm by scanning 500 times with 40% energy, and about 0.3mm by scanning 150 times with 50% energy per scan line by using the difference method.

In examples, the design target was 0.3mm wide and 0.3mm deep flow channels based on the results of preliminary experiments, the final design flow channels were as follows:

the diameter of the light spot is 50 um; the scanning interval is 20 um; the scanning frequency is 300 kHz; the scanning times are 150 times of scanning of each scanning line; the scanning speed is 1 m/s; the scan energy was 50% (maximum 80W).

Fig. 7 is an image of the focusing flow channel bottom 101 of the formed graphite bipolar plate obtained using the parameters described above. The bottom of the molded runner 101 has good flatness. A ridge 102 is formed between two adjacent runners 101.

The technical features of the above embodiments can be arbitrarily combined, for the sake of brevity, all possible combinations of the technical features in the above embodiments are not described, and particularly for the shape of the processing flow channel, the present patent only provides examples, and in the actual processing, due to the convenience of laser control, complex flow channel processing such as a bending flow channel, a flow channel with variable cross-sectional area, a micropore flow channel and the like can be realized, and a flow channel with a spatial shape can be processed by matching with the variable light path method shown in fig. 6.

The above-described examples merely represent several embodiments of the present application and are not to be construed as limiting the scope of the claims. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the concept of the present application, which falls within the scope of protection of the present application. Therefore, the protection scope of the present patent shall be subject to the appended claims.