JP2003249238A - Manufacturing method of grooved plate material, grooved plate material manufactured by the method - Google Patents

Abstract

(57) [Problem] To provide a method for manufacturing a grooved member, in which occurrence of breakage is suppressed. SOLUTION: This is a method for manufacturing a grooved plate material in which a plurality of grooves having a flat surface are formed in a metal plate 1A, the first die 2 having corrugated mold surfaces 20a, 20b.
A method of manufacturing a grooved plate material in which a metal plate 1A is preformed at 0A and 20B to form a plate material deformed into a corrugated shape, and then the plate material is completely formed by a second mold having a mold surface having the same shape as a groove portion to be formed. .

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a grooved plate material and a method for manufacturing the same, and more particularly, to a grooved plate material that can be used as a metal separator incorporated in a fuel cell, and manufactured by plastic working with a high yield. On how to do.

[0002]

2. Description of the Related Art A fuel cell, which has been expected as a clean energy source, is generally assembled as follows. First, an electrolyte layer is sandwiched between a fuel electrode and an air electrode to form a power generation element. A fuel passage is formed on one surface of the fuel electrode, and an air passage is formed on the other surface of the separator. Overlap the aisle side surfaces. Then, the air electrode side of another power generating element is arranged on the surface of the former separator on the air passage side, and the fuel electrode side of another power generating element is arranged on the surface of the latter separator on the fuel passage side.

In this way, the power generating elements are successively laminated via the separator to assemble a fuel cell having a predetermined number of stages. As a material for a separator incorporated in such a fuel cell, a graphite material has been mainly used in the past because of its excellent corrosion resistance against an electrolyte, low resistance and excellent conductivity.

By the way, recently, research and development of a fuel cell mounted on a vehicle have been actively conducted, but in that case, miniaturization of the fuel cell has become an important issue. For that purpose, it is necessary to reduce the thickness of the power generation element and the separator described above. However, if the graphite separator is made thinner, hydrogen, which is a fuel, will permeate and the function of the separator will be lost. Therefore, it is said that the thickness is limited to about 5 mm. At the same time, there is a problem that processing of fuel and air passages becomes very difficult and the cost becomes very high.

Under these circumstances, recently, a separator made of a thin metal plate has been proposed. An example of a typical metal separator is shown in FIG. This metal separator leaves a peripheral portion of one metal plate 1A in a frame shape,
A plurality of groove portions and a trapezoidal portion, which will be described later, are alternately arranged in parallel at a position excluding the peripheral portion.

FIG. 1 shows a part of a cross section taken along line XI-XI in FIG.
Shown in 1. In addition, in FIG. 11, the state in which the power generating elements are laminated on both surfaces of the metal separator 1 is shown by an imaginary line. This metal separator 1 has a groove portion A and a trapezoidal portion B. The groove A and the trapezoid B have the same cross-sectional shape, and they extend parallel to each other in the direction orthogonal to the plane of the drawing. At the time of assembling the fuel cell, the opening of the groove A is closed by the fuel electrode, and the top b ₁ of the trapezoidal portion B is in contact with the fuel electrode. Further, the opening of the trapezoidal portion B is sealed by the air electrode, and the bottom portion a ₁ of the groove portion A contacts the air electrode. Therefore, the groove A functions as a fuel passage, and the inside of the trapezoidal portion B functions as an air passage.

Here, both the bottom a ₁ of the groove A and the top b ₁ of the trapezoidal portion B have a large contact area with each pole of the power generating element so that the current from the power generating element can be efficiently extracted. It has a flat surface. In addition, the side surface a _{2 of the} groove A
Has a flat inclined surface rising from the bottom portion a _{1 at an} angle θ. This metal separator can be manufactured by plastic working using a mold. For example, as shown in FIG. 12, a pair of molds 2 in which the mold surfaces 2a and 2b have the same shape as the groove portion (or trapezoidal portion) of the target metal separator.
A metal plate 1A having a desired thickness (for example, 2 μm) between A and 2B
After arranging, the molds 2A and 2B may be pressed once.

[0008]

However, the above-mentioned manufacturing method has the following problems. In the die molding of FIG. 12 (hereinafter referred to as one-shot molding), as shown in FIG. 13, first, the trapezoidal portion of the die 2B comes into contact with the portion of the metal plate 1A located in the groove of the die 2A. . Then, that portion is pushed into the groove portion of the mold 2A at a stretch to form a desired uneven shape.

In this case, the portion 1a of the metal plate 1A is largely stretched to form the inclined surface a ₂ (b ₂ ) in the groove A (trapezoidal portion B) shown in FIG. 11, and the portion 1b is not stretched so much. Bottom surface a ₁ in groove A (trapezoid B)
(Top b ₁ ) is formed. That is, at the time of one-shot molding, the metal plate 1A is not uniformly stretched as a whole, but local elongation is generated around the portion formed on the inclined surface.

Therefore, the strain is concentrated on the portion formed on the inclined surface, the local elongation is concentrated there, and the breakage is likely to occur. Particularly, in the case of the metal separator shown in FIG. 10, since the plurality of groove portions A and the trapezoidal portion B are formed by one-shot molding while leaving the frame-shaped peripheral edge portion, the above-described local extension of the metal plate 1A is It becomes noticeable and breaks frequently.

When the metal plate 1A used is a cold-rolled material, distortion during rolling remains and its deformability is low, so that breakage easily occurs during one-shot molding, and the desired metal separator is obtained. Manufacturing yield is reduced. The present invention solves the above-mentioned problems in producing a grooved plate material by one-shot molding, almost no breakage of a metal plate during molding occurs, and a method for producing a grooved plate material with a high yield, and the method. A manufactured grooved plate material is provided.

[0012]

In order to achieve the above object, the present invention provides a method for producing a grooved plate material in which a plurality of groove portions each having a flat surface are formed on a metal plate. A metal plate that is preformed by a first mold having a corrugated mold surface into a corrugated shape, and then a second mold that has a mold surface having the same shape as the groove to be formed. The present invention provides a method for producing a grooved plate material, which comprises:

In this case, the height distance between the peaks and the troughs in the corrugated shape of the first mold is larger than the depth of the groove to be formed, and the corrugated shape of the first mold is used. In the vicinity of the peak of the mountain and the lowest point of the valley in
Both have a curved shape with a curvature of 0.3 mm or more.
Further, in the present invention, in the grooved plate material manufactured by the above method, a plurality of groove portions each having a flat bottom surface and side surface are formed in parallel with each other on the metal plate, There is provided a grooved plate material characterized in that the hardness in the vicinity of the bent portion of the groove is within the range of -40% to + 40% of the average hardness.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is a method for forming a plurality of groove portions, each of which has a flat bottom surface and a flat side surface, on a metal plate by carrying out two-step mold forming. First, as shown in FIG. 1, a metal plate 1A is placed between a pair of first molds 20A, 20B having mold surfaces 20a, 20b having the same corrugated shape, and then the first mold 20A, 20
Press molding with B at once (preliminary molding).

During this preforming, as shown in FIG. 2, _first , the apex 20a ₂ of the peak portion 20a _{1 on} the corrugated mold surface 20a of the mold 20A is the mold surface 20 of the mold 20B.
The portion of the metal plate 1A located immediately above the lowest point 20b ₂ of the valley portion 20b ₁ at point b is contacted, and then that portion is pushed all at once into the valley portion 2b ₁ to complete the forming. as a result,
Metal plate 1A, as shown in FIG. 3, deformed plate 1A ₁ in which the same waveform shape as the mold surface of the mold.

[0016] In this preformed, relatively in a state where the metal plate portion 1a which is located on both sides of the vertex 20a ₂ of the ridge portions 20a ₁ of the mold surface 20a of the mold 20A, 1a extends along the mold surface of the dies Since it is stretched uniformly, the locally concentrated elongation as in the case of the conventional one-shot molding shown in FIG. 13 does not occur. Therefore, the plate material 1A ₁ shown in FIG. 3 has the same shape as the mold surfaces of the pair of first molds, but the elongation is not locally concentrated there, and is uniform as a whole. Elongation processing is applied to prevent the occurrence of fracture.

The plate material 1A ₁ obtained by preforming was
As shown in Fig. 4, the groove (or trapezoid) of the target shape
Pair of second molds 2 in which the mold surfaces 2a and 2b are formed
It is arranged between A and 2B and press-molded (main molding). In that case, the crest of the plate 1A ₁ is the groove of the mold 2A, also valleys of the plate 1A ₁ is aligned to receive the crest portion of the die 2A.

In this main forming, since the plate material 1A ₁ in a uniform stretched state is compression-molded by the molds 2A and 2B, the plate material is not fractured at all and the molding proceeds.
1, the bottom surface a ₁ (top b ₁ ) and the inclined surface a _1
The groove portion A (or the trapezoid portion B) in which ₂ (b ₂ ) is a flat surface is formed. Here, in the vicinity of the apex 20a ₂ of the corrugated peak 20a ₁ (or the lowest point 20b of the valley 20b ₁ ) on the mold surface of the first mold used for preforming, a curved surface having a curvature of 0.3 mm or more Designed to be shaped.

If the curvature is less than 0.3 mm, the angle is too acute and the metal plate is likely to break through during preforming. Further, in the corrugated shape of the first mold, the lowest point 20b ₂ of the valley 20b ₁ and the peak 20a
Height distance (h) in the vertical direction from the vertex 20a _{2 of 1}
Is the target groove depth (or trapezoid height): H
On the other hand, it is designed to have a value of about 50 to 150%. This is because in the main forming, the vicinity of the top of the plate material 1A ₁ projects in the width direction and the height of the mountain portion becomes low, for example.

A preferable example of the corrugated shape on the die surface of the first die is a shape similar to a sin curve. By applying the present invention, even if the metal plate has a small deformability and is a thin cold-rolled material, it is possible to suppress the occurrence of breakage and form a large number of fine groove portions. For example, on an austenitic thin SUS plate,
A plurality of grooves are formed even on a clad plate having a thickness of about 0.15 mm, which is produced by plating a thin layer of several tens of nm of u, Pd, or Pt and cold rolling at a reduction rate of 5% or more. It can be formed to manufacture a metal separator for a fuel cell.

By the way, the bottom surface a ₁ as shown in FIG.
When a groove (or trapezoidal portion) in which both the inclined surface a ₂ and the inclined surface a ₂ are flat surfaces is formed by a single shot with a mold, the bent portion in the groove (or trapezoidal portion) is strongly processed. The hardness of is much higher than that of other parts, and the variation in hardness as a whole is large. However, as in the case of the present invention, if the groove portion (or trapezoidal portion) having the above-described shape is formed in the main forming after performing the preliminary molding, the bent portion in the groove portion (or trapezoidal portion) is as described above. Since it is not subjected to heavy working, the hardness of the portion is higher than the hardness of other portions, but is lower than the case of the above-described one-shot molding, and therefore the variation in hardness as a whole is small.

When the method of the present invention is applied, in the finally formed groove portion (or trapezoidal portion), the hardness of the bent portion is -40% to +40 with respect to the average value of the hardness of the whole plate material.
Within the range of%, the variation is small.

[0023]

EXAMPLES Examples 1 to 4, Comparative Examples 1 and 2 The following metal separators were used as molding targets. First, as shown in FIG. 5, the grooves to be formed have a pitch between the grooves A-A of 2.7 mm, a depth H of the grooves A (and a height of the trapezoid B) of 0.7 mm, and a groove A of the grooves A. Bottom a ₁ and top b _{1 of} trapezoid B
Has a width of 0.9 mm, and the angle θ of the inclined surface is tan ^-1 (0.9.
7 / 0.45), the curvature of the bent part of the groove A is 0.05 mm,
The curvature of the bent portion of the trapezoidal portion B is 0.25 mm.

On the other hand, as a metal plate, a SUS316 plate having a plate thickness of 0.2 mm and a hardness (HV) of 170 to 180,
After plating SUS316 plate with Au of thickness 40nm, 1
Cold rolling was performed at a rolling reduction of 5%, and two types of clad plates having a plate thickness of 0.2 mm and a hardness (HV) of 310 to 330 were prepared. Further, as the first mold for preforming, a pair of molds (1) whose mold surfaces have the corrugated shape shown in FIG.
A pair of molds (2) whose mold surfaces have the corrugated shape shown in FIG. 7 and a pair of molds (3) whose mold surfaces have the corrugated shape shown in FIG. 8 were prepared.

After preforming a metal plate with each first mold,
The plate material thus obtained was subjected to main molding with a pair of molds whose mold surfaces had the shape shown in FIG. 5 to mold a grooved plate material. For comparison, one-shot molding was performed using a mold having a mold surface having the same shape as in FIG. 5 to manufacture a grooved plate material. With respect to the obtained plate material, the presence or absence of breakage in the groove portion (and the trapezoidal portion) was visually observed. The case where no rupture was observed was ◯, and the case where even one rupture was observed was x.

The results are shown in Table 1.

[0027]

[Table 1]

As is apparent from Table 1, HV: 170-
With respect to the SUS316 plate of 180, the target grooved plate material can be manufactured without causing breakage regardless of which mold is used. On the other hand, HV: 310
~ 330 for high hardness clad plate, mold (1)
Even when preforming is performed, the peaks of the ridges are sharp, and fracture occurs. However, by using the mold (2) and the mold (3) in which the peaks of the ridges have a large curvature, the target grooved plate material can be manufactured without causing breakage.

Next, using a SUS316 plate having a thickness of 0.2 mm and an HV value of 248, one-shot molding using the mold having the mold surface shown in FIG. 5 was carried out to manufacture a plate material (Comparative Example 2). Further, a plate material (Example 4) was manufactured by carrying out the method of the present invention using the mold having the mold surface shown in FIG. 7, and at each position of 5 groove portions and 5 trapezoidal portions for each plate material. Hardness (HV) was measured. The average value of hardness measured at all points is shown in FIG. Also, the average hardness of the plate material, (maximum hardness-average hardness) x
100 / average hardness, (minimum hardness-average hardness) x 100 /
The average hardness is shown in Table 2.

[0030]

[Table 2]

As is clear from FIG. 9 and Table 2, in the method of the present invention, the hardness of the bent portion in the manufactured plate material is low and the variation thereof is small as compared with the conventional one-shot molding. .

[0032]

As is apparent from the above description, according to the present invention, when a groove portion and a trapezoidal portion each having a flat bottom surface and a flat side surface are formed into a single metal plate, After preforming a metal plate using a mold with a mold surface,
Since main forming is performed with a die having a regular shape, the concentration of elongation on the inclined surface of the groove is suppressed, and the metal plate breakage that occurred in conventional one-shot forming does not occur, so The grooved plate material can be manufactured with a high yield.

The present invention is extremely effective when applied to the production of a metal separator incorporated in a fuel cell.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of a mold used for preforming of the present invention.

FIG. 2 is a cross-sectional view showing a plate material obtained by preforming.

FIG. 3 is an explanatory diagram for explaining the reason why breakage of a metal plate is suppressed during preforming.

FIG. 4 is a sectional view showing the main molding of the present invention.

FIG. 5 is an explanatory view illustrating specifications of dimensions and shapes of a groove portion and a trapezoid portion which are targets in the embodiment.

FIG. 6 is a view showing a waveform shape of a mold surface of a mold (1) used for preforming.

FIG. 7 is a view showing a waveform shape of a mold surface of a mold (2) used for preforming.

FIG. 8 is a view showing a waveform shape of a mold surface of a mold (3) used for preforming.

9 is a graph showing the hardness distributions of the plate material of Example 4 and the plate material of Comparative Example 2. FIG.

FIG. 10 is a perspective view showing an example of a metal separator.

11 is a sectional view taken along line XI-XI of FIG.

FIG. 12 is a cross-sectional view showing conventional one-shot molding.

FIG. 13 is an explanatory diagram for explaining the reason why elongation concentrates on an inclined surface in one-shot molding.

[Explanation of symbols]

1A Metal plate 1A ₁ Plate material obtained by preforming A Groove portion B Trapezoidal portion 2A, 2B Molds 2a, 2b having target shape mold surfaces 2A, 2B Mold surfaces 20A, 20B Mold 20a, 20b Mold surface 20a ₁ of mold 20A, 20B ₁ peak 20a ₂ peak 20b ₁ peak 20b ₁ valley 20b ₂ valley 20b ₁ lowest point

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Takeo Hisada             2-30, Daido-cho, Minami-ku, Nagoya-shi, Aichi             Daido Steel Co., Ltd. Technology Development Laboratory (72) Inventor Shinobu Takagi             2-30, Daido-cho, Minami-ku, Nagoya-shi, Aichi             Daido Steel Co., Ltd. Technology Development Laboratory F term (reference) 5H026 AA02 BB02 BB04 CC03 CC05                       EE02 HH00 HH03 HH05

Claims (7)

[Claims] 1. A method for manufacturing a grooved plate material, which comprises forming a plurality of groove portions having a flat surface on a metal plate, wherein the metal plate is preliminarily prepared by a first mold having a corrugated mold surface. A method for manufacturing a grooved plate material, which comprises forming a plate material deformed into a corrugated shape, and then finally forming the plate material with a second mold having a mold surface having the same shape as the target groove portion. 2. The method for manufacturing a grooved plate material according to claim 1, wherein the height distance between the peak and the valley in the corrugated shape of the first mold is larger than the depth of the groove targeted for formation. 3. A curved shape having a curvature of 0.3 mm or more in the vicinity of the peak of the peak and the lowest point of the valley in the corrugated shape of the first mold.
For manufacturing a grooved plate material. 4. The method for manufacturing a grooved plate member according to claim 1, wherein the groove is formed at a position excluding the peripheral edge of the metal plate. 5. The metal plate is Au, Pt, or Pd.
A method for producing a grooved plate material according to any one of claims 1 to 4, which is a clad plate on which a thin layer made of is formed on the surface and which is cold-rolled at a rolling reduction of 5% or more. 6. A plurality of groove portions each having a flat bottom surface and side surface are formed in parallel with each other on a metal plate, and a hardness in the vicinity of a bent portion of the groove portions is an average hardness of −40. % To + 40%, a grooved plate material characterized by being in the range of + 40%. 7. The grooved plate material according to claim 6, which is a metal separator incorporated in a fuel cell.