ROLLER EMBOSSING METHOD FOR FLEXIBLE GRAPHITE POLAR PLATES OF FUEL CELLS

Abstract

A roller embossing method for flexible graphite polar plates of fuel cells comprises: (1) adjusting a clearance of an embossing roller pair of a roller press to a target thickness value of a monopolar plate; (2) feeding a flexible graphite slab in front of the embossing roller pair, and entangling the flexible graphite slab by means of opposite rotation of the embossing roller pair; (3) after the slab is entangled, continuing to forward roll the slab for 10-100 mm, and then reversely rolling the slab for 5-90 mm by means of synchronous and opposite rotation of an upper and a lower embossing roller, wherein one time of forward rolling and one time of reverse rolling are referred to as reciprocal rolling; (4) forming a polar plate after several times of reciprocal rolling, and separating the polar plate from the embossing rollers; (5) performing subsequent treatment on the roll-formed flexible graphite polar plate.

Claims

1. A roller embossing method for flexible graphite polar plates of fuel cells, an embossing roller pair in mirror symmetry being manufactured according to structural features of patterns of a polar plate to be formed, the embossing roller pair being mounted on a roller press to be applied to a continuous production line to produce the polar plate, and the method comprises: step (1) adjusting a clearance of the embossing roller pair of the roller press to a target thickness value of a monopolar plate; step (2) feeding, by a feed device, a flexible graphite slab in front of the embossing roller pair, and entangling the flexible graphite slab by means of opposite rotation of the embossing roller pair; step (3) after the flexible graphite slab is entangled, continuing to forward roll the flexible graphite slab for 10-100 mm, and then reversely rolling the flexible graphite slab for 5-90 mm by means of synchronous and opposite rotation of an upper embossing roller and a lower embossing roller, wherein one time of forward rolling and one time of reverse rolling are referred to as reciprocal rolling; step (4) forming the polar plate after several times of reciprocal rolling, and separating the polar plate from the embossing roller pair; and step (5) performing subsequent treatment on the rolled flexible graphite polar plate.

2. The roller embossing method for flexible graphite polar plates of fuel cells according to claim 1, wherein the target thickness value of the monopolar plate is 0.4-1.2 mm.

3. The roller embossing method for flexible graphite polar plates of fuel cells according to claim 1, wherein the embossing roller pair comprises the upper embossing roller and the lower embossing roller that are arranged in a mirror symmetry manner, a diameter of the upper embossing roller and a diameter of the lower embossing roller are 200-600 mm, and two motors are used to drive the upper embossing roller and the lower embossing roller of the roller press, respectively.

4. The roller embossing method for flexible graphite polar plates of fuel cells according to claim 3, wherein the two motors are servo motors and synchronously drive the upper embossing roller and the lower embossing roller.

5. The roller embossing method for flexible graphite polar plates of fuel cells according to claim 1, wherein in the step (1), the roller press is adjusted to accurately align the embossing roller pair in a front-back direction and a left-right direction to avoid deviations of flow fields of the rolled flexile graphite polar plate.

6. The roller embossing method for flexible graphite polar plates of fuel cells according to claim 1, wherein in the step (2), a feed speed of the feed device is 5-75 s/pieces.

7. The roller embossing method for flexible graphite polar plates of fuel cells according to claim 1, wherein in the step (3), during each time of reciprocal rolling, a reverse rolling distance is 5-10 mm smaller than a forward rolling distance to ensure that the flexible graphite slab is able to move forwards after each time of reciprocal rolling.

8. The roller embossing method for flexible graphite polar plates of fuel cells according to claim 1, wherein in the step (3), a forward rotation speed of the embossing roller pair is 3-30 cm/s, and a reverse rotation speed is equal to the forward rotation speed.

9. The roller embossing method for flexible graphite polar plates of fuel cells according to claim 1, wherein during multiple times of reciprocal rolling, a clearance between the upper embossing roller and the lower embossing roller is equal to a thickness of the polar plate to be prepared and remains unchanged in the rolling process, and a rolling pressure is 3-25 ton.

10. The roller embossing method for flexible graphite polar plates of fuel cells according to claim 1, wherein when the polar plate is produced by a set distance by multiple times of reciprocal rolling, the roller press returns to an original point.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0028] FIG. 1 is a schematic diagram of primary forward rolling of a reciprocal roller embossing process of the invention.

[0029] FIG. 2 is a schematic diagram of primary reverse rolling of the reciprocal roller embossing process of the invention.

[0030] FIG. 3 is a schematic diagram of secondary forward rolling of the reciprocal roller embossing process of the invention.

[0031] FIG. 4 is a schematic diagram of secondary reverse rolling of the reciprocal roller embossing process of the invention.

[0032] FIG. 5 is a schematic diagram of another type of rolling by embossing rollers of the reciprocal roller embossing process of the invention.

[0033] In the figures: 1, upper embossing roller; 11, polar plate pattern corresponding to upper embossing roller; 2, lower embossing roller; 21, polar plate pattern corresponding to lower embossing roller; 3, non-rolled flexible graphite slab; 4, rolled flexible graphite slab; 5, upper embossing roller; 51, polar plate pattern corresponding to upper embossing roller; 6, lower embossing roller; 61, polar plate pattern corresponding to lower embossing roller.

DESCRIPTION OF THE EMBODIMENTS

[0034] The embodiments of the invention will be described in detail below and are implemented on the basis of the technical solution of the invention. Detailed implementations and specific operation processes are given below. But, the protection scope of the invention is not limited to the following embodiments.

Embodiment 1

[0035] A rolled flexible graphite monopolar plate with a thickness of 0.75 mm and a length of 300 mm was prepared by means of an embossing roller pair, shown in FIG. 1, which comprised an upper embossing roller 1 and a lower embossing roller 2, wherein the upper embossing roller 1 was provided with a corresponding polar plate pattern 11, the lower embossing roller 2 was provided with a corresponding polar plate pattern 21, and a lengthwise direction, corresponding to the embossing patterns, the polar plate was parallel to the direction of roller surfaces. A non-rolled flexible graphite slab 3 was placed in front of the embossing roller pair and was formed through the following method.

[0036] Step 1: a clearance between the upper embossing roller 1 and the lower embossing roller 1 was adjusted to 0.75 mm.

[0037] Step 2: the non-rolled flexible graphite slab 3 was fed between the upper embossing roller 1 and the lower embossing roller 2 by a feed device and was entangled by means of the upper embossing roller 1 and the lower embossing roller 2, that rotate oppositely, to be rolled forward for 30 mm, wherein a rolled flexible graphite slab 4 was shown in FIG. 1.

[0038] Step 3: as shown in FIG. 2, the upper embossing roller 1 and the lower embossing roller 2 rotated reversely and drove the flexible graphite slab 3 to be reversely rolled for 20 mm, and at this moment, the embossing patterns of the upper embossing roller 1 and the lower embossing roller 2 partially overlapped with the rolled flexible graphite slab 4.

[0039] Step 4: as shown in FIG. 3, the upper embossing roller 1 and the lower embossing roller 2 continued to forward roll the flexible graphite slab 3 for 30 mm.

[0040] Step 5: as shown in FIG. 4, the upper embossing roller 1 and the lower embossing roller 2 continued to reversely roll the flexible graphite slab 3 for 20 mm, and reciprocal rolling was performed 27 times.

[0041] Step 6: after 27 times of reciprocal rolling, the flexible graphite slab 4 was further rolled forward, and a rolled polar plate was conveyed out forwards to be separated from the embossing rollers, so that rolling of the polar plate was completed.

Embodiment 2

[0042] A rolled flexible graphite monopolar plate with a thickness of 1.0 mm and a width of 180 mm was prepared by means of embossing rollers shown in FIG. 5, wherein the embossing rollers comprised an upper embossing roller 5 provided with a corresponding polar plate pattern 51, as well as a lower embossing roller 6 provided with a corresponding polar plate pattern 61, and a lengthwise direction, corresponding to the embossing rollers, of the polar plate was perpendicular to the direction of roller surfaces.

[0043] Step 1: a clearance between the upper embossing roller 5 and the lower embossing roller 6 in FIG. 5 was adjusted to 1.0 mm.

[0044] Step 2: a flexible graphite slab was fed between the upper embossing roller 5 and the lower embossing roller 6 by a feed device and was entangled by the upper embossing roller 5 and the lower embossing roller 6, that rotate oppositely, to be forward rolled for 50 mm.

[0045] Step 3: the upper embossing roller 5 and the lower embossing roller 6 rotated reversely to drive the flexible graphite slab to be reversely rolled for 30 mm, wherein the embossing patterns of the upper embossing roller 5 and the lower embossing roller 6 partially overlapped with polar plate patterns rolled in Step 2.

[0046] Step 4: the upper embossing roller 5 and the lower embossing roller 6 continued to forward roll the flexible graphite slab for 50 mm.

[0047] Step 5: the upper embossing roller 5 and the lower embossing roller 6 continued to reversely roll the flexible graphite slab for 30 mm, and reciprocal rolling was performed 8 times.

[0048] Step 6: after 8 times of reciprocal rolling, the flexible graphite slab was further forward rolled, and a rolled polar plate was conveyed out forwards to be separated from the embossing rollers, so that rolling of the polar plate was completed.

Embodiment 3

[0049] According to a roller embossing method for flexible graphite polar plates of fuel cells in this embodiment, in Step 1, a clearance of a roller press provided with a pair of embossing rollers with patterns of a polar plate to be formed was adjusted to a target thickness value 0.4 mm of a monopolar plate, wherein the diameter of the embossing rollers was 200 mm; a flexible graphite slab was roller-embossed multiple times and was then rolled forward for 10 mm; and the slab was reversely rolled for 5 mm.

[0050] This embodiment was identical with Embodiment 1 in other aspects.

Embodiment 4

[0051] According to a roller embossing method for flexible graphite polar plates of fuel cells in this embodiment, in Step 1, a clearance of a roller press provided with a pair of embossing rollers with patterns of a polar plate to be formed was adjusted to a target thickness value 1.2 mm of a monopolar plate, wherein the diameter of the embossing rollers was 600 mm; a flexible graphite slab was roller-embossed multiple times and was then rolled forward for 100 mm; and the slab was reversely rolled for 90 mm.

[0052] This embodiment was identical with Embodiment 1 in other aspects.

[0053] The properties of the polar plates prepared through the methods in the above embodiments are as follows:

TABLE-US-00001 Embodiment Embodiment Embodiment Embodiment Detection 1 2 3 4 method Landing 0.6 mm 0.6 mm 0.5 mm 0.5 mm 3D profilometer Center distance 1.3 mm 1.3 mm 1.2 mm 1.2 mm 3D profilometer Channel depth 0.4 mm 0.4 mm 0.42 mm 0.42 mm 3D profilometer Draft angle 200 20° 10° 10° 3D profilometer Forming time 34 s 15 s 63 s 8 s Stop watch Electrical <5 mΩ .Math. cm.sup.2 <5 mΩ .Math. cm.sup.2 <5 mΩ .Math. cm.sup.2 <5 mΩ .Math. cm.sup.2 DC voltage and conductivity current source Air-tightness <0.01 sccm <0.01 sccm <0.01 sccm <0.01 sccm Leakage detector Mechanical Bending Bending Bending Bending Universal performance resistance resistance resistance resistance tensile tester >25 MPa >25 MPa >25 MPa >25 MPa Compression Compression Compression Compression resistance resistance resistance resistance >6 MPa >6 MPa >6 MPa >6 MPa Corrosion <1 μA/cm.sup.2 <1 μA/cm.sup.2 <1 μA/cm.sup.2 <1 μA/cm.sup.2 Electrochemical resistance workstation