JP5271728B2 - Manufacturing method of thin metal plate with irregularities formed - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a thin metal sheet on which recessed and projecting parts are formed, wherein a high quality molding is obtained by suppressing the surface strain in a planar part during forming. <P>SOLUTION: In a press working method of the thin metal sheet W' for forming the recessed and projecting parts on the thin metal sheet W' by press forming with a die 10, the recessed and projecting parts are formed on the thin metal sheet W' through a preliminary bulging stage for forming the approximate shape of the recessed and projecting parts on the thin metal sheet W' by bulging the thin metal sheet W' from the initial stage of the forming until reaching just before the final stage of the forming and a crushing stage where a material which is taken in at the preliminary bulging stage is returned to the origin part to the vertical wall part Wc of the groove by crushing the vertical wall parts Wc of the thin metal sheet W' with the die 10 and also the whole of the thin metal sheet W' is pressed. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a method for manufacturing a metal thin plate having uneven portions formed by press molding with a mold.

  For example, a metal separator used in a polymer electrolyte fuel cell is obtained by pressing a metal thin plate such as stainless steel or titanium alloy and applying a highly corrosion-resistant coating or the like. In this way, a current collecting section having a corrugated cross section that is alternately continuous is formed. Here, the concave portion of the current collecting portion becomes a gas flow passage or a flow passage such as generated water after reaction, and the convex portion becomes a portion in contact with the gas diffusion electrode plate of the electrode structure.

  By the way, although a metal separator is shape | molded by the bulging forming by press work, a curvature (curvature of the whole separator) and surface distortion (surface undulation around a current collection part) may generate | occur | produce in the metal separator after shaping | molding. Are known. In the metal separator, elastic recovery (spring back) occurs when the irregular shape of the current collector is formed, which causes warpage of the metal separator.

  Further, in the manufacture of the metal separator, when the current collecting part WA is formed on the metal thin plate W ′ by overhanging as shown in FIG. 8, the material of the peripheral part WB of the current collecting part WA is indicated by an arrow in FIG. The material is moved in the direction of the current collector WA. This material movement is large in the vertical part and the horizontal part of the current collecting part WA, but is small in the corner parts (four places indicated by X in FIG. 8) of the current collecting part WA. Distortion occurs.

  As described above, when warpage or surface distortion occurs in the fuel cell metal separator, the convex portion of the current collector does not contact the gas diffusion electrode plate with sufficient surface pressure, or the surface pressure becomes uneven, resulting in contact resistance. It becomes large and causes a decrease in generated voltage. Also, in the work of assembling a fuel cell by laminating a plurality of electrode structures with the metal separator sandwiched between them, it is necessary to assemble while correcting the warp and surface distortion of the metal separator, so the work is complicated and the work efficiency is high. In addition to being bad, there is a problem that the gas sealing performance is lowered.

  Therefore, Patent Document 1 proposes a plate material pressing method that can suppress warping of a molded product due to elastic recovery of the plate material in the manufacture of a fuel cell metal separator or the like. This method will be described below with reference to FIGS.

  That is, FIGS. 9A to 9C are partial cross-sectional views showing the state of deformation of the plate material by press working, and the illustrated method uses the concave (upper) 81 and convex (lower) shown in FIG. 9 (a). The first step of forming the overhanging portion 101 on the plate material 100 using the first press die 80 composed of the die 82, the concave die (upper die) 91 and the convex die (lower) shown in FIGS. The second press die 90 consisting of a die 92 is used to perform press working in at least two steps of the second step of completing the projection 102.

  In the second step, as shown in FIG. 9B, pressing is performed so as to press the side wall portion in the vicinity of the peripheral portion of the overhang portion 101 by the opening portion of the concave portion 91 a formed in the concave die 91. For this reason, when the overhanging portion 101 is formed on the surface of the plate member 100 in the first step, a bending moment that causes elastic recovery is applied in the vicinity of the overhanging portion 101, but FIG. When the projection 102 is completed as shown in c), the deformation is applied to the concave portion 91 side portion of the peripheral portion of the projection 102. When the press working is performed so that the elongation deformation becomes necessary and sufficient to cancel the bending moment causing the elastic recovery, the entire plate thickness direction becomes the expansion deformation, and the elastic recovery is achieved. Defects such as warping due to the shape are suppressed.

JP 2000-317531 A

  However, the press working method proposed in Patent Document 1 can solve the problem of warping of the metal separator, but cannot solve the problem of surface distortion around the current collector, and the performance of the fuel cell There has been no solution to the deterioration of durability or assembly work efficiency.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a method for manufacturing a metal thin plate in which high-quality concavo-convex portions are formed while suppressing surface distortion during molding.

In order to achieve the above-mentioned object, the invention according to claim 1 is characterized in that the thin metal plate is formed by press molding with a mold , and the linear shape is inclined from the edge of the concave portion toward the edge of the convex portion. In order to press the metal thin plate on which the concavo-convex part formed of the groove vertical wall part of
A pre-extrusion step in which at least the metal thin plate is stretched to form a rough shape on the metal thin plate;
A crushing step of crushing the groove vertical wall portion of the uneven portion of the metal thin plate to return the material drawn into the groove vertical wall portion during the preliminary overhanging step and pressing the entire metal thin plate,
A method of manufacturing via
The clearance between the upper mold and the lower mold for molding the vertical wall portion of the mold in the crushing step is as follows:
The method of manufacturing a metal thin plate with a concavo-convex portion formed , wherein the dimension is determined so that the amount of crushing of the metal thin plate is the same as the amount of material drawn into the vertical wall portion of the groove in the preliminary overhanging step .

The invention according to claim 2 is the invention according to claim 1 or 2, wherein the groove of the metal thin plate formed in the pre-extrusion step is formed by a mold in which a space is formed between the pre-extraction step and the crushing step. A metal thin plate is manufactured through a second preliminary projecting step in which the vertical wall portion is crushed and the material flows into the mold space.

A third aspect of the invention is characterized in that, in the second aspect of the invention, the thin metal sheet is manufactured by repeating the second preliminary overhanging step and the crushing step a plurality of times.

According to a fourth aspect of the present invention, in the first aspect of the present invention, a third preliminary overhanging step is performed before the preliminary overhanging step so as to secure a volume necessary for the rough shape of the uneven portion in the preliminary overhanging step. It is characterized by manufacturing through.

  According to the first aspect of the present invention, the material drawn into the vertical wall portion of the groove from the peripheral portion of the groove by the extension forming of the thin metal plate in the preliminary overhanging step is used for the vertical wall portion of the thin metal plate in the next crushing step. Since it is returned to the original groove peripheral part by crushing, only the groove vertical wall part of the metal thin plate is crushed and extended like forging. For this reason, since the material drawn into the groove vertical wall portion from the groove peripheral portion is returned from the groove vertical wall portion to the groove peripheral portion, a high-quality molded product with reduced surface distortion can be obtained.

In addition, according to the first aspect of the present invention, by appropriately setting the clearance of the groove vertical wall portion molding portion of the mold, the amount of squeezing of the metal thin plate in the squeezing step is the groove vertical wall of the material in the preliminary overhanging step. It can be set to be the same amount as the amount drawn into the part, and the amount of material drawn between the peripheral part other than the molded part and the molded part while keeping the cross-sectional area (volume) of the molded part of the metal thin plate constant The return amount becomes the same amount, and the occurrence of surface distortion accompanying the movement of the material can be suppressed.

According to the inventions of claims 2 and 3 , the vertical wall portion of the groove is formed in the metal thin plate to a height that can be formed by a normal overhanging process in the pre-step of the pre-overhanging step, and the post-step of the pre-overhanging step ( Forming a space in the mold in the second pre-extrusion step), crushing the vertical wall portion of the groove of the thin metal sheet formed in the previous step and allowing the material to flow into the space, thereby allowing extra space for use in the crushing step Form. By adding a post process of the pre-extrusion process, as long as the material can flow out, even a material with a higher unevenness or a material with a small elongation can be molded.

According to the fourth aspect of the present invention, when the overhanging process cannot be performed in the preliminary overhanging process according to the first aspect, the volume required for forming the rough shape of the concavo-convex portion in the preliminary overhanging process in the previous process of the preliminary overhanging process. The metal sheet is stretched so as to ensure the ruggedness, and in the next process (crushing process), the material that has flowed into the vertical wall of the groove of the metal sheet in the previous process is stretched and formed to have a desired height. The part can be molded.

It is a perspective view of the metal separator for fuel cells shape | molded by the manufacturing method of the metal thin plate in which the uneven | corrugated | grooved part based on this invention was formed. It is the sectional view on the AA line of FIG. (A), (b) is the fragmentary sectional view of the metal mold | die which each shows the preliminary | backup extension process and crushing process of the manufacturing method which concerns on Embodiment 1 of this invention. (A), (b) is sectional drawing before and behind shaping | molding of the groove | channel vertical wall part shaping | molding part (intermediate linear part) of a metal thin plate in the manufacturing method which concerns on Embodiment 1 of this invention. (A), (b) is a perspective view before and behind shaping | molding of the groove | channel vertical wall part shaping | molding part (edge curved surface part) of a metal thin plate in the manufacturing method which concerns on Embodiment 1 of this invention. (A)-(c) is the pre-process of the preliminary overhang process of the manufacturing method which concerns on Embodiment 2 of this invention, and the post process of a preliminary overhang process (The gold | metal | money which each shows a 2nd preliminary overhang process and a crushing process) It is a fragmentary sectional view of a type | mold. (A)-(c) shows the pre-process (3rd preliminary | backup extension process) of the preliminary | backup extension process of the manufacturing method which concerns on Embodiment 3 of this invention, the post process of a preliminary | backup extension process, and a crushing process, respectively. It is a fragmentary sectional view of a metal mold | die. It is a perspective view which shows the movement condition of the material at the time of the press work of a metal thin plate. (A)-(c) is a fragmentary sectional view which shows the deformation | transformation state of the board | plate material by the press work method proposed in patent document 1. FIG.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

  FIG. 1 is a perspective view of a metal separator for a fuel cell formed by the method for manufacturing a metal thin plate having a concavo-convex portion according to the present invention, and FIG. 2 is a cross-sectional view taken along line AA of FIG.

  The metal separator W for fuel cells shown in FIG. 1 is obtained by pressing a thin metal plate W ′ (see FIG. 3A) having a thickness of 0.1 to 0.2 mm made of, for example, stainless steel, A current collector WA is formed at the center, and the periphery of the current collector WA is surrounded by a flat peripheral portion WB.

  As shown in detail in FIG. 2, the current collector WA constitutes a corrugated plate having a corrugated cross section in which concave portions Wa and convex portions Wb formed by a plurality of groove vertical wall portions Wc are alternately continued in the surface direction. The concave portion Wa serves as a gas flow channel or a flow channel such as product water after reaction, and the convex portion Wb serves as a portion that contacts a gas diffusion electrode plate of an electrode structure (not shown). The fuel cell metal separator W shown in FIG. 1 is used for a polymer electrolyte fuel cell, and a fuel cell stack is assembled by laminating a plurality of electrode structures while sandwiching them. .

  Thus, the fuel cell metal separator W shown in FIG. 1 is formed by the manufacturing method according to the present invention. Hereinafter, an embodiment of the manufacturing method according to the present invention will be described.

<Embodiment 1>
3 (a) and 3 (b) are partial cross-sectional views of the mold showing the preliminary overhanging step and the crushing step of the press working method according to Embodiment 1 of the present invention, and FIGS. 4 (a) and 4 (b) are views. Sectional views before and after forming the groove vertical wall forming part (intermediate straight line part) of the metal thin plate, FIGS. 5 (a) and 5 (b) are before and after forming the groove vertical wall forming part (end curved surface part) of the metal thin plate. It is a perspective view. 3 to 5 show a part of a mold or a thin metal plate for convenience of explanation, and the uneven portion formed in the current collector WA of the actual fuel cell metal separator W shown in FIG. It does not correspond to the number of Wa and Wb.

  The manufacturing method according to the present invention is a method of forming an uneven portion on a metal thin plate through a pre-extrusion step and a crushing step, and the pre-extrusion step stretches the metal thin plate from the initial stage of forming to immediately before the end of forming. It is a process of forming the rough shape of the concavo-convex portion on the metal thin plate by extrusion molding. This is a step of returning the original material and pressing the entire thin metal plate. Hereinafter, the preliminary overhanging step and the crushing step will be specifically described.

1) Preliminary overhanging process:
In the manufacturing method according to the present embodiment, a mold 10 comprising an upper mold 11 and a lower mold 12 shown in FIG. 3 is used, and the upper mold 11 has a current collector for a fuel cell metal separator W shown in FIG. A concave portion 11a having a trapezoidal cross section corresponding to the shape of the convex portion Wb (see FIG. 2) of the portion WA is formed, and the concave portion Wa (see FIG. 2) of the current collecting portion WA of the metal separator W is formed in the lower mold 12. The convex part 12a of the cross-sectional trapezoid shape corresponding to the shape of is formed.

  Thus, in the preliminary overhanging process, as shown in FIG. 3A, the metal thin plate W ′ as a material is inserted and set between the upper mold 11 and the lower mold 12, and in this state, the upper mold 11 is It is lowered by a pressing mechanism (not shown).

  FIG. 3 (a) shows a state in the initial stage of molding. In this state, the metal sheet W ′ is subjected to normal bulging by the elongation of the material itself, and as the upper die 11 is lowered, the metal sheet W ′ is deformed. The material of the portion forming the groove vertical wall portion Wc is stretched and deformed, and accordingly, the surrounding material is drawn into the groove vertical wall portion Wc as indicated by the arrow. When the preliminary overhanging process is completed and the process proceeds to the crushing process of the next process, the rough shape Wa and Wb (see FIG. 2) of the metal thin plate W has been formed in the metal thin plate W ′.

2) Crushing process:
In the crushing step, as shown in FIG. 3 (b), the groove vertical wall portion Wc of the metal thin plate W 'is crushed by the upper mold 11 and the lower mold 12 at the final stage of molding when the upper mold 11 descends to near the bottom dead center. The material drawn into the groove vertical wall portion Wc during the pre-extrusion step is returned to the original groove peripheral portion, and the entire metal thin plate W ′ is pressed to obtain the fuel cell metal separator W shown in FIG. .

  Here, the clearance between the groove vertical wall portion forming portions of the upper die 11 and the lower die 12 is the same as the amount of material squeezed into the groove vertical wall portion Wc in the preliminary overhanging step. Determined to be a quantity. Specifically, the cross-sectional area of the thin metal plate W ′ shown in FIG. 4A before forming the groove vertical wall portion forming portion (intermediate straight line portion) is the same as that after forming the thin metal plate W ′ shown in FIG. What is necessary is just to determine the clearance (plate thickness of the groove | channel vertical wall part Wc after shaping | molding) of the groove | channel vertical wall part shaping | molding part of the upper mold | type 11 and the lower mold | type 12 so that it may become equal to the cross-sectional area of the groove | channel vertical wall part Wc.

  That is, assuming that the forming range of the groove vertical wall Wc of the metal thin plate W ′ is a and the plate thickness of the metal thin plate W ′ before forming is ta, the groove vertical wall forming of the metal thin plate W ′ shown in FIG. The cross-sectional area Sa before forming the part (intermediate straight line part) is obtained by the following equation.

Sa = a × ta (1)
Further, when the thickness of the groove vertical wall portion Wc after forming the thin metal plate W ′ is tb and the height is c, the cross-sectional area Sb of the groove vertical wall portion Wc of the thin metal plate W ′ after forming is as follows: Desired.

Sb = √ (a ² + c ² ) × tb (2)
The thickness tb of the vertical wall portion of the groove after forming a thin metal plate satisfying Sa = Sb = S is obtained as follows from equations (1) and (2).

tb = (a × ta) / √ (a ² + c ² ) (3)
Therefore, the clearance of the groove vertical wall portion forming portion of the upper die 11 and the lower die 12 is set to tb obtained by the expression (3), and the clearance other than the groove vertical wall portion Wc is set to the plate of the metal thin plate W ′ before forming. If the thickness ta is set, the amount of squeezing of the metal thin plate W ′ in the squeezing step can be made equal to the amount of material drawn into the groove vertical wall portion Wc in the preliminary overhanging step.

  Also, in the curved end portion of the groove vertical wall portion of the metal thin plate W ′, the amount of the metal thin plate W ′ in the crushing step is the amount of material drawn into the groove vertical wall portion Wc in the preliminary overhanging step. The clearance of the groove vertical wall portion molding portion of the upper die 11 and the lower die 12 is determined so as to be the same amount. That is, the volume Va before forming the groove vertical wall forming portion (the end curved surface portion shown by hatching) of the metal thin plate W ′ shown in FIG. 5A is the metal thin plate W ′ shown in FIG. 5B. Of the groove vertical wall portion of the upper die 11 and the lower die 12 so as to be equal to the volume Vb after forming of the groove vertical wall portion forming portion (end curved surface portion indicated by hatching) (Va = Vb). Clearance is determined.

  As described above, according to the manufacturing method according to the present embodiment, the material drawn into the groove vertical wall portion Wc from the groove peripheral portion of the metal thin plate W ′ by the overhang forming of the metal thin plate W ′ in the preliminary overhanging step. In the next crushing step, the groove vertical wall portion Wc of the metal thin plate W ′ is returned to the original groove peripheral portion by crushing, so that only the groove vertical wall portion Wc of the metal thin plate W ′ is crushed and stretched like forging. It is. For this reason, the movement of the material is performed only within the range of the molded part including the peripheral part of the groove of the thin metal plate W ′, and the cross-sectional area (volume) of the molded part does not change. There is no inflow / outflow of material between the molding part and the molding part, generation of surface distortion accompanying the inflow / outflow of material is suppressed, and a high-quality metal separator W for fuel cells (see FIG. 1) is obtained.

  Specifically, the amount of crushing of the metal thin plate W ′ in the crushing process is set to be a material in the pre-extrusion process by appropriately setting the clearance between the groove vertical wall forming portions of the upper mold 11 and the lower mold 12 of the mold 10. Can be set to be the same as the amount drawn into the vertical wall portion Wc of the groove, and the cross-sectional area (volume) of the forming portion of the metal thin plate W ′ is kept constant, between the peripheral portion other than the forming portion and the forming portion Inflow and outflow of material at the surface can be eliminated, and the occurrence of surface distortion accompanying the inflow and outflow of material can be suppressed.

  And in this Embodiment, the high quality metal separator W for fuel cells without a surface distortion can be efficiently shape | molded in a short time with one metal mold | die. The method of the present invention can be applied regardless of the material of the metal thin plate W ′ and the dimensions of the concave and convex portions Wa and Wb to be formed, and can be arbitrarily applied to the metal thin plate W ′ of any material such as stainless steel, aluminum, titanium, etc. The uneven portions Wa and Wb of the size can be formed. In this embodiment, the molding is performed with one mold, but the same effect can be obtained even when the preliminary overhanging process and the crushing process are performed with different molds.

<Embodiment 2>
Next, a second embodiment of the present invention will be described with reference to FIGS.

  6 (a) to 6 (c) show the pre-process of the pre-expansion process, the post-process of the pre-expansion process (second pre-expansion process), and the crushing process of the manufacturing method according to Embodiment 2 of the present invention. It is a fragmentary sectional view of a metallic mold shown, respectively.

  The manufacturing method according to the present embodiment is a method of adding a post-expansion step (second pre-expansion step) between the pre-expansion step and the crushing step. In the subsequent process, the metal sheet is stretched to a moldable height, a space is formed in the mold in the subsequent process of the preliminary stretching process, and the material is obtained by crushing the vertical wall portion of the metal sheet formed in the previous process. It is characterized by flowing into the space. Further, the post-process and the crushing process of the preliminary overhanging process can be repeated multiple times. Hereinafter, the method will be specifically described with reference to FIGS.

1) Preliminary overhanging process (previous process):
In this preliminary overhanging step (previous step), as shown in FIG. 6A, the concavo-convex portions Wa and Wb (groove vertical walls) shown in FIG. A mold 20 comprising an upper mold 21 formed with a recess 21a (shallow) lower than a height (depth) of the portion Wc) and a lower mold 22 formed with a projection 22a is used. A metal thin plate W ′, which is a material, is inserted and set between the molds 22, and the upper mold 21 is lowered by a press mechanism (not shown) in this state.

  FIG. 6 (a) shows the completed state of the process prior to the preliminary overhanging step. In this state, normal overhanging is performed by the elongation of the material itself, and as the upper die 21 is lowered, the metal thin plate W ′ is moved. The material of the portion forming the groove vertical wall portion Wc is stretched and deformed, and accordingly, the surrounding material is drawn into the groove vertical wall portion Wc as indicated by the arrow. In the pre-step of the preliminary overhanging step, the groove vertical wall Wc is formed on a metal thin plate to a height that can be formed by a normal overhanging process, and rough shapes Wa and Wb (see FIG. 2) are formed. The Note that the pre-step of the preliminary overhanging step corresponds to the preliminary overhanging step of the first embodiment.

2) Preliminary overhanging process (post process):
In the subsequent process of the preliminary overhanging process, as shown in FIG. 6B, a mold 30 including an upper mold 31 in which a recess 31a deeper than the recess 21a of the upper mold 21 used in the previous process is formed. A space V is formed between the upper mold 31 and the lower mold 32 of the mold 30. In this step, the groove vertical wall portion Wc of the metal thin plate W ′ formed in the previous step is crushed to allow the material to flow into the space V, thereby forming a surplus wall for use in the next crushing step.

3) Crushing process:
In the crushing step, as shown in FIG. 6 (c), the height (depth) of the uneven portions Wa, Wb (groove vertical wall portion Wc) of the fuel cell metal separator W shown in FIG. A vertical wall portion Wc including a surplus wall formed on the metal thin plate W ′ in the previous step is used, which is a mold 40 including an upper die 41 having a concave portion 41a and a lower die 42 having a convex portion 42a. However, in the final stage of molding when the upper die 41 is lowered to the vicinity of the bottom dead center, the upper die 41 and the lower die 42 are crushed, and the material drawn into the groove vertical wall portion Wc in the preliminary overhanging process is returned to the original groove peripheral portion. At the same time, the entire thin metal plate W ′ is pressed, and the fuel cell metal separator W shown in FIG. 1 is obtained.

  Here, as in the first embodiment, the clearance between the groove vertical wall portion forming portions of the upper die 41 and the lower die 42 is such that the amount of crushing of the metal thin plate W ′ in the crushing step is the length of the groove of the material in the preliminary overhanging step. It is determined to be the same amount as the amount drawn into the wall Wc.

  Thus, also in the present embodiment, the material drawn into the groove vertical wall portion Wc from the groove peripheral portion of the metal thin plate W ′ by the stretch forming of the metal thin plate W ′ in the pre-stretching step is In the process, the groove vertical wall portion Wc of the thin metal plate W ′ is returned to the original groove peripheral portion by crushing, so there is no material inflow / outflow between the peripheral portion other than the forming portion and the forming portion. As a result, the occurrence of surface distortion associated with is suppressed, and a high-quality metal separator W for fuel cells is obtained.

  In particular, in the present embodiment, the groove vertical wall portion Wc is formed in the metal thin plate W ′ in the previous process of the pre-extrusion process to a moldable height that does not cause cracks and necks by the normal extension process, and in the next process. A space V is formed in the mold 30, and the groove vertical wall portion Wc of the thin metal plate W ′ formed in the previous process is crushed to allow the material to flow into the space V, thereby forming a surplus for use in the crushing process. As long as the material can flow out, higher concavo-convex portions Wa and Wb (see FIG. 2) can be formed, or even a material with less elongation can be formed.

  Also, prepare a plurality of molds for the preliminary overhanging process and the crushing process. First, perform the preliminary process for the preliminary overhanging process, and then perform the preliminary process for the preliminary overhanging process and the crushing process multiple times. You can also In this case, it is possible to mold a higher uneven portion or even a difficult-to-mold material with less material elongation.

<Embodiment 3>
Next, a third embodiment of the present invention will be described with reference to FIGS.

  7 (a) to 7 (c) are a pre-step (third pre-projection step) before the pre-extension step of the manufacturing method according to Embodiment 3 of the present invention, a post-step of the pre-extension step, and It is a fragmentary sectional view of the metal mold | die which each shows a crushing process.

  In the manufacturing method according to the present embodiment, the third preliminary overhanging step (preliminary step) is performed before the preliminary overhanging step so as to secure the volume necessary for forming the rough shape in the preliminary step. It is characterized by being manufactured through a pre-process of the overhang process. Hereinafter, the method will be specifically described with reference to FIGS.

1) Preliminary overhanging process (previous process):
In this preliminary overhanging step (previous step), a normal overhang forming is performed on the metal thin plate W ′ using a mold 50 including an upper die 51 and a lower die 52 shown in FIG. 7A. The required volume for the next process is ensured in the extrusion process. In this overhang molding, the material of the portion forming the groove vertical wall portion Wc of the metal thin plate W ′ is stretched and deformed as the upper mold 51 is lowered, and the surrounding material is grooved as indicated by the arrow along with this. It is drawn into the vertical wall Wc.

2) Preliminary overhanging process (post process):
In the subsequent process of the preliminary projecting process, a mold 60 including an upper mold 61 and a lower mold 62 shown in FIG. 7B is used, and the material that has flowed into the groove vertical wall portion Wc of the metal thin plate W ′ in the previous process is used. The overhanging process is carried out. In this subsequent process, the material that has flowed into the groove vertical wall portion Wc in the previous process is used as it is, so that the material does not flow in and out, but the material in the previous process flows into the groove vertical wall portion Wc. Along with the inflow, surface distortion is still generated on the outer periphery (flat portion) of the groove vertical wall Wc. Note that the pre-step of the preliminary overhanging step corresponds to the preliminary overhanging step of the first embodiment.

3) Crushing process:
In the crushing step, as shown in FIG. 7C, the height (depth) of the concavo-convex portions Wa and Wb (groove vertical wall portions Wc) shown in FIG. 2 of the fuel cell metal separator W shown in FIG. ) Is used, and the groove vertical wall portion Wc is crushed by using a mold 70 composed of an upper mold 71 in which a concave portion equivalent to the above is formed and a lower mold 72 in which a convex portion 72a is formed, and a preliminary overhanging process (previous process) 1 flows out to the flat portion on the outer periphery of the groove vertical wall portion Wc, and the two materials are offset to form the fuel cell metal separator W shown in FIG.

  Here, as in the first and second embodiments, the clearance between the groove vertical wall portion forming portions of the upper mold 71 and the lower mold 72 is equal to the amount of crushing of the metal thin plate W ′ in the crushing process. It is determined to be the same amount as the amount drawn into the groove vertical wall portion Wc.

  Thus, also in the present embodiment, the material drawn into the groove vertical wall portion Wc from the groove peripheral portion of the metal thin plate Wc by the extension forming of the metal thin plate W ′ in the preliminary overhanging step is subjected to the next crushing step. In this case, by crushing the groove vertical wall portion Wc of the thin metal plate W ′, the material is returned to the peripheral portion of the original groove. Therefore, there is no inflow / outflow of material between the peripheral portion other than the forming portion and the forming portion. The generation of surface distortion is suppressed, and a high-quality metal separator W for fuel cells without warping or undulation is obtained.

  In particular, in this embodiment, when stretch forming cannot be performed in one process due to the elongation limit of the material, the metal thin plate W ′ is stretched and formed so as to secure a necessary volume in the next process in the previous process of the preliminary projecting process. In the next step, since the overflow molding is performed using the material that has flowed into the groove vertical wall portion Wc of the thin metal plate W ′ in the previous step, the uneven portion Wa having a desired height is formed on the fuel cell metal separator W. Wb can be formed.

  In the above, the embodiment in which the present invention is applied to the molding of a metal separator for a fuel cell has been described. However, the present invention can also be applied to press processing of any other molded product formed by forming an uneven portion on a thin metal plate. Of course, the same applies.

DESCRIPTION OF SYMBOLS 10 Mold 11 Upper mold 11a Concavity of upper mold 12 Lower mold 12a Convex section of lower mold 20 Mold 21 Upper mold 21a Concavity of upper mold 22 Lower mold 22a Convex section of lower mold 30 Mold 31 Upper mold 31a Upper mold 31a Recess 32 Lower mold 32a Lower mold protrusion 40 Mold 41 Upper mold 41a Upper mold recess 42 Lower mold 42a Lower mold protrusion 50 Mold 51 Upper mold 52 Lower mold 60 Mold 61 Upper mold 62 Lower mold 70 Gold Mold 71 Upper mold 71a Upper mold concave part 72 Lower mold 72a Lower mold convex part V Space W Metal separator for fuel cell W 'Metal thin plate WA Current collector (uneven part) of metal separator for fuel cell
WB Peripheral part of fuel cell metal separator Wa Concave part of current collecting part Wb Convex part of current collecting part Wc Vertical wall part of groove of current collecting part

Claims (4)

The metal thin plate was press-molded with a metal mold to form a concave and convex portion including a concave portion, a convex portion, and a linear groove vertical wall portion inclined from the edge of the concave portion toward the edge of the convex portion . To press the metal sheet,
A pre-extrusion step in which at least the metal thin plate is stretched to form a rough shape on the metal thin plate;
A crushing step of crushing the groove vertical wall portion of the uneven portion of the metal thin plate to return the material drawn into the groove vertical wall portion during the preliminary overhanging step and pressing the entire metal thin plate,
A method of manufacturing via
The clearance between the upper mold and the lower mold for molding the vertical wall portion of the mold in the crushing step is as follows:
The method of manufacturing a metal thin plate with a concavo-convex portion formed , wherein the dimension is determined so that the amount of crushing of the metal thin plate is the same as the amount of material drawn into the vertical wall portion of the groove in the preliminary overhanging step .   A second spare in which a metal mold in which a space is formed between the preliminary overhanging step and the crushing step collapses the vertical wall portion of the groove of the thin metal sheet formed in the preliminary overhanging step and allows the material to flow into the mold. 2. The method for producing a metal thin plate having a concavo-convex portion formed thereon according to claim 1, wherein the metal thin plate is produced through an overhanging step. Method for producing the second preliminary overhanging step and the metal sheet an uneven portion of claim 2, wherein is formed, characterized in that to produce the crushing step is repeated a plurality of times. The uneven portion according to claim 1 , wherein the uneven portion is manufactured through a third preliminary extending step before the preliminary extending step so as to secure a volume necessary for the rough shape of the uneven portion in the preliminary extending step. The manufacturing method of the metal thin plate in which this was formed.

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