A flexible graphite plate continuous rolling forming device and its application

Abstract

The present invention relates to a flexible graphite plate continuous rolling forming device and its application. The device comprises a feeding mechanism for delivering flexible graphite slabs (1) and a continuous rolling mill for forming flexible graphite plates (4); the continuous rolling mill comprises a pair of mirror-image-made printing rollers for final forming of the flexible graphite plates (4) and at least one pair of mirror-image-made printing rollers for auxiliary forming of the flexible graphite plates (4), the printing roller pair comprising an upper printing roller (32) and a lower printing roller (33); the feeding mechanism is located between the upper printing roller (32) and the lower printing roller (33). Compared with the prior art, the present invention utilizes a continuous rolling process to produce ultra-thin flexible graphite plates, with a single plate thickness ranging from 0.4 to 1.2 mm, thereby achieving continuous and highly automated production and significantly improving production efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of graphite bipolar plate production, and in particular to a flexible graphite plate continuous rolling forming device and application thereof. Background Art

[0002] Flexible graphite plates, due to their low cost, excellent corrosion resistance, and good thermal and electrical conductivity, are considered the most promising alternative to machined hard graphite plates. This has attracted the attention of numerous fuel cell companies and research institutes, who have invested significant manpower and resources in related R&D. Among existing process development, the most commonly used flexible graphite forming process is vacuum flat pressing. U.S. Patent No. 6797091B2 was the first to propose a vacuum flat pressing method for flexible graphite plates, successfully applied in fuel cell production. To achieve higher forming efficiency, reduce manual intervention, and achieve truly continuous and automated plate forming, researchers have long pursued the application of rolling (rolling) processes to flexible graphite plate forming. U.S. Patent No. 6818165B2, filed by Ballard in 2002 and published in 2004, is the earliest publicly available patent mentioning roll-pressed flexible graphite plates. However, this process only mentions roll-pressing as a concept, without actual application in production.

[0003] Existing patented technologies suffer from the following issues: 1. Poor molding quality, significant deviations between the actual and designed flow field depths (greater than 25%), and plate blistering, among other serious defects; 2. Excessive plate thickness (making them impractical for automotive applications); 3. Excessive ridge width (>0.8mm), shallow flow field depth (<0.3mm), excessive ridge center distance (>1.5mm), and excessive draft angle (>30°). These issues directly prevent existing roll-pressing processes from producing flexible graphite plates suitable for automotive fuel cell applications. Summary of the Invention

[0004] The present invention aims to overcome at least one of the above-mentioned drawbacks of the prior art by providing a flexible graphite plate continuous rolling forming apparatus and its application. This method enables the continuous, automated, and highly efficient production of ultra-thin, non-stretched flexible graphite plates with narrow ridges, short center distances, deep grooves, and small draft angles.

[0005] The present invention utilizes a unidirectional, multi-pass continuous rolling mill. Each mill stand is equipped with a pair of embossed rollers imprinted with the pattern of the electrode plate to be formed. A continuous row of press rollers is positioned between the mill stands to prevent the electrode plates from warping. Each set of embossed rollers and anti-warping press rollers rotates in opposite directions, gradually thinning the flexible graphite slab through rolling. This ultimately enables continuous rolling to produce electrode plates with high surface quality and no defects such as blistering.

[0006] The purpose of the present invention can be achieved by the following technical solutions:

[0007] One of the purposes of the present invention is to provide a flexible graphite plate continuous rolling forming device, which includes a feeding mechanism for delivering flexible graphite slabs and a continuous rolling mill for forming flexible graphite plates;

[0008] The continuous rolling mill comprises a group of mirror-image-made embossing roller pairs for final forming of flexible graphite plates and at least one group of mirror-image-made embossing roller pairs for auxiliary forming of flexible graphite plates.

[0009] The printing roller pair includes an upper printing roller and a lower printing roller; the continuous rolling mill group also includes at least two rolling mill supports, the upper printing roller is located above the rolling mill support, and the lower printing roller is located below the rolling mill support. The printing rollers are printed with the pattern of the electrode plate to be formed.

[0010] The feeding mechanism is located between the upper printing roller and the lower printing roller.

[0011] Furthermore, the feeding mechanism includes a guide vertical roller, a feeding roller, a cutting circular saw and a positioning feeding roller, and the feeding roller is located between the upper printing roller and the lower printing roller.

[0012] Furthermore, the continuous rolling mill group also includes a series of anti-warping rollers located between the rolling mill supports to prevent the electrode plates from warping.

[0013] Furthermore, the roller diameter of the printing roller ranges from 150 to 600 mm.

[0014] Furthermore, the diameter of the anti-warping continuous pressure rollers ranges from 5 to 50 mm, and the distance between the roller surfaces ranges from 5 to 20 mm.

[0015] Furthermore, the thickness of the flexible graphite plate is 0.4 to 1.2 mm.

[0016] The second object of the present invention is to provide an application of the flexible graphite plate continuous rolling forming device as described above, which includes the following steps:

[0017] Adjust the printing rollers of each rolling mill bracket to ensure that the upper and lower printing rollers are accurately aligned front to back and left to right to prevent the flow field of the rolled flexible graphite plate from being misaligned.

[0018] The gap between the embossing rollers of the mill stands is adjusted so that the gap between the embossing rollers of the current mill stand is reduced by 5-20% compared to the gap between the previous mill stand; wherein the gap between the embossing rollers of the first mill stand is reduced by 5-40% compared to the slab thickness, preferably by 30-40%. The gap between the embossing rollers of the subsequent row of rollers of each mill stand is the same as the gap between the embossing rollers at the front row.

[0019] The feeding roller of the feeding mechanism is used to deliver the flexible graphite slab to the front of the printing roller pair. The upper and lower printing rollers rotate in opposite directions at the same time to bite the flexible graphite slab, and the anti-warping continuous pressure rollers press the process edge area of ​​the graphite plate to ensure the stability of the plate and transport it to the next rolling mill bracket.

[0020] Specifically, each set of embossing rollers and anti-warping pressure rollers rotate in opposite directions, and the flexible graphite slab is gradually thinned through gradual rolling, thereby ultimately achieving continuous rolling production of plates with high surface quality and no quality defects such as bubbling.

[0021] The flexible graphite slab is formed by continuous rolling in the continuous rolling mill and separated from the embossing roller of the last rolling mill support to obtain a flexible graphite plate.

[0022] Furthermore, the pattern size of the current rolling mill support is proportionally extended by 0-2.5% along the length direction of the roller surface and 0-0.5% along the width direction of the roller surface compared to the previous rolling mill support. The pattern size of the printed roller of the last rolling mill support is equivalent to the actual design value.

[0023] Furthermore, the feed roller, upper printing roller, lower printing roller and anti-warping continuous pressure roller have the same roller surface linear speed when working, and the linear speed range is 0.05 to 20 m / s, such as 0.1, 1, 5 and 10 m / s. Specifically, the linear speed of the printing roller needs to match the plate length factor to ensure that the printing and the printed pattern of the plate are correctly aligned when each rolling mill bracket bites into the plate. The flexible graphite slab is delivered to the front end of the continuous rolling mill through the feeding mechanism, and the vertical roller device is used to ensure that the slab is accurately bitten into the first group of rolling mill brackets;

[0024] Compared with the prior art, the present invention has the following advantages:

[0025] (1) The present invention utilizes a continuous rolling process to produce ultra-thin flexible graphite plates, with a single-pole plate thickness ranging from 0.4 to 1.2 mm, thereby achieving continuous and highly automated production and significantly improving production efficiency.

[0026] (2) The present invention realizes the roll forming of non-stretched flexible graphite plates with narrow ridges, short center distances, large groove depths, and small draft angles. The range of forming conditions completely covers the flat pressing process, and the surface forming quality is better than that of the flat pressing process of the same plate type.

[0027] (3) The present invention has no restrictions on plate shape or flow field structure. All plate shape designs that can be realized by the flat pressing process can be realized by the roller pressing process of this patent;

[0028] (4) The present invention can realize ultra-high-speed continuous plate forming. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 Schematic diagram of a flexible graphite plate continuous rolling forming device;

[0030] The numbers in the figure are as follows: 1-flexible graphite slab; 2-feeding mechanism, 21-guide vertical roller, 22-feeding roller, 23-cutting circular saw; 24-positioning feed roller; 3-continuous rolling mill group, 31-rolling mill support, 32-upper printing roller, 33-lower printing roller, 34-anti-warping continuous pressure roller, 35-discharging funnel; 4-flexible graphite monopolar plate. DETAILED DESCRIPTION

[0031] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0032] A flexible graphite plate continuous rolling forming device, comprising a feeding mechanism for delivering a flexible graphite slab 1 and a continuous rolling mill unit 3 for forming a flexible graphite plate 4;

[0033] The continuous rolling mill 3 includes a pair of mirror-image embossing rollers for final forming of the flexible graphite plate 4 and at least one mirror-image embossing roller pair for auxiliary forming of the flexible graphite plate 4. The embossing roller pair includes an upper embossing roller 32 and a lower embossing roller 33. A feed mechanism is located between the upper and lower embossing rollers 32, 33. The continuous rolling mill 3 also includes at least two mill supports 31: the upper embossing roller 32 is located above the mill supports 31, and the lower embossing roller 33 is located below the mill supports 31. The feed mechanism includes guide rollers, feed rollers, a cutting circular saw, and a positioning feed roller. The feed roller is located between the upper and lower embossing rollers 32, 33. The continuous rolling mill 3 also includes a warping prevention roller tandem 34 located between the mill supports 31. The embossing rollers have a diameter ranging from 150 to 600 mm. The anti-warping roller tandem 34 has a diameter ranging from 5 to 50 mm, and the roller surface spacing is 5 to 20 mm. The thickness of the flexible graphite electrode 4 is 0.4-1.2 mm.

[0034] Example 1

[0035] In this embodiment, a 4 mm thick flexible graphite slab 1 is rolled at a linear speed of 3 m / s to prepare a flexible graphite plate 4 with a thickness of 0.65 mm, a length of 400 mm, and a width of 145 mm. Figure 1As shown, the tandem mill group uses a six-pass tandem mill group 3, with a reduction ratio of 30% for the first and second passes, 35% for the third pass, 30% for the fourth pass, 20% for the fifth pass, and 9% for the sixth pass. Furthermore, the embossing rollers used in the fifth and sixth passes have the same dimensions as those used for the flexible graphite plate 4. The embossing roller used in the fourth pass is 1.5% longer in length and 0.4% longer in width than the fifth pass. The embossing roller used in the third pass is 1.8% longer in length and 0.5% longer in width than the fourth pass. The embossing roller used in the second pass is 1.1% longer in length and 0.2% longer in width than the third pass. The embossing roller used in the first pass is 0.9% longer in length and 0.1% longer in width than the second pass.

[0036] Step 1: Adjust the roll gap of each mill stand to the target value based on the reduction rate for each pass. The roll gap of the first mill stand is adjusted to 2.80mm, the second mill stand to 1.96mm, the third mill stand to 1.27mm, the fourth mill stand to 0.89mm, the fifth mill stand to 0.71mm, and the sixth mill stand to 0.65mm. The corresponding anti-warping rollers are also adjusted to the same roll gap as the front mill stand.

[0037] Step 2: Use feed rollers 22 to transport the 4mm thick flexible graphite slab 1 toward the continuous rolling mill 3. Use guide rollers 21 to adjust the slab's direction to ensure no significant deviation during transport. The flexible graphite slab 1 is transported to the front end of the cutting circular saw 23. Positioning feed rollers 24 with a 4mm roll gap engage the flexible graphite slab 1 and cut it through the cutting circular saw 23. Immediately after cutting, the flexible graphite slab enters the positioning feed rollers 24 with a similar 4mm roll gap. The linear speed of each roller is 3m / s, and the spacing between each pair of vertical rollers is adjusted to 150mm.

[0038] Step 3: The flexible graphite slab 1 is transported to the rolling mill support 31 via the continuous positioning feed rollers 24, and is bitten into the flexible graphite slab 1 by the upper and lower printing rollers 32 and 33. The upper and lower printing rollers 32 and 33 rotate in opposite directions at a linear speed of 3m / s. The 4mm flexible graphite slab 1 is rolled to 2.80mm by the rolling mill support 31, and then further transported backward to the anti-warping continuous pressing rollers 34. The anti-warping continuous pressing rollers 34 and the feed rollers 22 bite into the plate process edge, and continue to be transported to the repeated rolling unit at the rear end until the sixth rolling pass is completed and the material is discharged through the discharge funnel 35. At this point, the continuous rolling process of the plate is completed, and the flexible graphite monopolar plate 4 is produced.

[0039] Example 2

[0040] Example 2: A 3 mm thick flexible graphite slab 1 was rolled at a linear speed of 5 m / s to prepare a flexible graphite plate 4 having a thickness of 0.5 mm, a length of 420 mm, and a width of 155 mm. Figure 1 The flexible graphite plate continuous rolling mill 3 shown in the figure uses a five-pass continuous rolling mill, with the first pass having a reduction of 40%, the second pass having a reduction of 39%, the third pass having a reduction of 35%, the fourth pass having a reduction of 22%, and the fifth pass having a reduction of 10%. Furthermore, the embossing roller used in the fifth pass has the same dimensions as the actual plate. The embossing roller used in the fourth pass is 0.6% longer in length and 0.1% longer in width than the fifth pass. The embossing roller used in the third pass is 0.6% longer in length and 0.1% longer in width than the fourth pass. The embossing roller used in the second pass is 0.5% longer in length and 0.1% longer in width than the third pass. The embossing roller used in the first pass is 0.5% longer in length and 0.1% longer in width than the second pass.

[0041] Step 1: Adjust the roll gap of each mill stand to the target value based on the reduction rate for each pass. The roll gap of the first mill stand is adjusted to 1.80mm, the second mill stand to 1.10mm, the third mill stand to 0.71mm, the fourth mill stand to 0.56mm, and the fifth mill stand to 0.50mm. The corresponding anti-warping rollers are also adjusted to the same roll gap as the front mill stand.

[0042] Step 2: Use feed rollers 22 to transport the 3mm thick flexible graphite slab 1 toward the continuous rolling mill 3. Use guide rollers 21 to adjust the direction of the flexible graphite slab 1 to ensure that it does not deviate significantly during transportation. The flexible graphite slab 1 is transported to the front end of the cutting circular saw 23. Use positioning feed rollers 24 with a roller gap of 3mm to bite into the flexible graphite slab 1. The flexible graphite slab 1 is cut by the cutting circular saw 23 and immediately enters the positioning feed rollers 24 with a roller gap of 3mm. The linear speed of each roller is 5m / s, and the distance between each pair of vertical rollers is adjusted to 160mm.

[0043] Step 3: The flexible graphite slab 1 is transported to the rolling mill support 31 via the continuous array of positioning feed rollers 24, where it is bitten into the flexible graphite slab 1 by the upper and lower embossing rollers 32 and 33. The upper and lower embossing rollers 32 and 33 rotate in opposite directions at a linear speed of 5 m / s. The 3 mm sheet 1 is rolled to 1.80 mm by the rolling mill support 31, and then conveyed back to the anti-warping continuous array of press rollers 34. The anti-warping continuous array of press rollers 34 and the feed rollers 22 bite into the plate process edge, and then conveyed to the repeated rolling unit at the rear end until the fifth rolling pass is completed and the sheet is discharged through the discharge funnel 35. At this point, the continuous rolling process of the plate is completed, and the flexible graphite monopolar plate 4 is produced.

[0044] Because flexible graphite is a porous, loose, discontinuous phase material, it exhibits two characteristics: 1. The greater the degree of primary processing, the poorer its secondary forming ability; and 2. The material's formability is inversely proportional to its degassing capacity. Existing techniques pre-roll-press flexible graphite slabs to eliminate post-molding surface bubbles without requiring additional degassing methods. This results in a lack of sufficient secondary forming ability, resulting in a large amount of flakes (surface quality defects) on the post-molding surface and significant deviations between the designed and actual values ​​(typically exceeding 30% in depth deviation).

[0045] The present invention utilizes a single-direction, multi-pass continuous rolling mill. Each mill stand is equipped with a pair of embossed rollers printed with the pattern of the electrode plate to be formed. A continuous row of press rollers is positioned between the mill stands to prevent the electrode plates from warping. Each set of embossed rollers and anti-warping press rollers rotate in opposite directions, gradually thinning and shaping the flexible graphite slab through rolling. This ultimately enables continuous rolling to produce electrode plates with high surface quality and no defects such as blistering.

[0046] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any other manner. Any person skilled in the art may utilize the above-disclosed technical content to modify or modify the present invention into equivalent embodiments. However, any simple modifications, equivalent variations, and modifications to the above embodiments that do not depart from the technical content of the present invention and are based on the technical essence of the present invention remain within the scope of protection of the present invention.

Claims

1. Application of a flexible graphite plate continuous rolling forming device, characterized in that: The device comprises a feeding mechanism for delivering flexible graphite slabs (1) and a continuous rolling mill group (3) for forming flexible graphite plates (4); The continuous rolling mill (3) includes a pair of mirror-image-made embossing rollers for final shaping of the flexible graphite plate (4) and at least one pair of mirror-image-made embossing rollers for auxiliary shaping of the flexible graphite plate (4); The feeding mechanism comprises a guide vertical roller (21), a feeding roller (22), a cutting circular saw (23) and a positioning feeding roller (24); the feeding roller (22) is used to transport the flexible graphite slab (1) toward the continuous rolling mill (3); the guide vertical roller (21) is used to adjust the direction of the flexible graphite slab (1); the flexible graphite slab (1) is transported to the front end of the cutting circular saw (23); the positioning feeding roller (24) is used to bite into the flexible graphite slab (1); and the flexible graphite slab (1) is cut by the cutting circular saw (23); and after cutting, the flexible graphite slab enters the positioning feeding roller (24); The device is used for continuous rolling of flexible graphite plates, and includes the following steps: Adjust the printing roller gap of the mill stand. The printing roller gap thickness of the current mill stand is reduced by 5~20% compared with the previous mill stand. The flexible graphite slab (1) is delivered to the front of the printing roller pair by using the feeding roller (22) of the feeding mechanism, the upper printing roller (32) and the lower printing roller (33) rotate in opposite directions at the same time to bite the flexible graphite slab (1), and the anti-warping continuous pressing roller (34) presses the flexible graphite slab (1); The flexible graphite slab (1) is continuously rolled and formed by a continuous rolling mill (3) to obtain a flexible graphite plate (4); The pattern size of the current rolling mill support is proportionally extended by 0~2.5% along the length direction of the roller surface and by 0~0.5% along the width direction of the roller surface compared to the pattern size of the previous rolling mill support; the working rolling force of the embossed roller is 2~30 MPa; and the working rolling force of the anti-warping continuous pressure roller (34) is 0.1~3 MPa.

2. The application of the flexible graphite plate continuous rolling forming device according to claim 1, characterized in that: The printing roller pair comprises an upper printing roller (32) and a lower printing roller (33); the continuous rolling mill group (3) further comprises at least two rolling mill supports (31), the upper printing roller (32) being located above the rolling mill supports (31), and the lower printing roller (33) being located below the rolling mill supports (31).

3. The application of the flexible graphite plate continuous rolling forming device according to claim 1, characterized in that: The continuous rolling mill group (3) further comprises a continuous row of anti-warping pressure rollers (34) located between the rolling mill supports (31).

4. The application of the flexible graphite plate continuous rolling forming device according to claim 1, characterized in that: The roller diameter of the printing roller ranges from 150 to 600 mm.

5. The application of the flexible graphite plate continuous rolling forming device according to claim 1, characterized in that: The anti-warping continuous pressure rollers (34) have a roller diameter range of 5 to 50 mm, and a roller surface spacing range of 5 to 20 mm.

6. The application of the flexible graphite plate continuous rolling forming device according to claim 1, characterized in that: The thickness of the flexible graphite plate (4) is 0.4-1.2 mm.

7. The application of the flexible graphite plate continuous rolling forming device according to claim 1, characterized in that: The feed roller (22), the upper printing roller (32), the lower printing roller (33) and the anti-warping continuous pressure roller (34) have the same roller surface linear speed when working, and the linear speed range is 0.05~20 m / s.

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