JP2007048616A - Fuel cell separator, device and method for manufacturing separator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a device and a method for manufacturing a separator capable of suppressing crack, distortion and bend. <P>SOLUTION: In a fuel cell separator formed by carrying out coining process after forming irregularity in a separator material 70 to have a corrugated cross section, a shoulder part 88 located in neighbors of an irregular apex part is formed with compounded curved surfaces. The compounded curved surface comprise at least a first curved surface with curvature radius R1 and a second curved surface with curvature radius R2, and it is preferable that R1>R2. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a fuel cell separator provided in a single cell of a fuel cell, an apparatus and a method for manufacturing the separator, and more particularly to an invention capable of suppressing distortion of the separator.

  A single cell in a fuel cell, for example, a fixed polymer fuel cell, is composed of an MEA (Membrane Electrode Assembly) composed of an electrolyte membrane and a pair of electrodes disposed on both sides thereof, and a pair of separators sandwiching the MEA. A fuel cell stack is formed by stacking such single cells. In such a fuel cell, an oxidizing gas or a fuel gas is supplied to each electrode through a gas flow path formed in each separator, thereby generating a single cell.

When a fuel cell separator as described above, such as a metal separator, is formed, first, the separator material is formed with irregularities and formed into a cross-sectional corrugated shape, and then coined (see, for example, Patent Document 1). .
JP 2000-67888 A

  However, in such a technique, for example, if the cross section of the fuel cell separator is formed so as to have the same curvature, the material has a large local elongation, and cracking, distortion, and warping (warping) may occur. In addition, when the separator is a thin plate, distortion, warpage, and the like are likely to occur due to stress acting on the uneven portion. Since the fuel cell is configured by stacking a large number of separators, when the separator is distorted as described above, the contact surface with the MEA, the conductive resistance between the separators, the sealing performance of gas and cooling water, It is difficult to ensure stackability. Therefore, when manufacturing a fuel cell separator, it is important to suppress the occurrence of cracks, distortion, and warpage.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a fuel cell separator, a separator manufacturing apparatus, and a separator manufacturing method capable of suppressing generation of cracks, distortion, and warpage.

In order to solve this problem, the present inventor has made various studies. Cracks, distortion, warpage, and the like that may occur in a separator used in a fuel cell are affected by various factors. That is, the thickness (original thickness) t ₀ of the separator material at the time before processing, the shape of the fluid flow path formed by the unevenness, the ridges and valleys of the unevenness (in the present specification, these are collectively referred to as the “top portion of the unevenness ”), The shape of the bent or curved part (referred to herein as“ shoulder ”), the depth of the groove formed by the unevenness, the pitch of the unevenness, the thickness of the separator (in other words, For example, various distortions and warpage occur due to the influence of the height of the unevenness. As a result of further examination of such an event, the present inventor has come to know a technique that makes it possible to minimize warping and the like.

  The present invention is based on such knowledge, and the invention according to claim 1 is a fuel cell separator formed by coining after forming a corrugated separator material into a corrugated cross section, and The shoulder portion located on both sides of the top portion is composed of a curved surface combined.

  The compound curved surface in this case is preferably composed of at least a first curved surface having a curvature radius R1 and a second curved surface having a curvature radius R2, and R1> R2, as in claim 2. .

Further, as in claim 3, the forming length, which is the length along the corrugated section of one pitch among the plurality of the irregularities formed, is l _R, and for corrugating used in the coining process When the coining length, which is the length along the molding surface for one pitch among the irregularities in the mold, is defined as l _C , the ratio of l _R and l _C is
0.98 ≦ l _R / l _C ≦ 1.02
It is preferable that the relationship is satisfied.

Furthermore, in the fuel cell separator according to claim 2, as in claim 4, the curvature radius R1 of the first curved surface, the curvature radius R2 of the second curved surface, and a material original thickness of the separator material. For t ₀
(R1 + R2) / t ₀ > 1
It is still more preferable that the relationship is satisfied.

Further, the invention according to claim 5 is the fuel cell separator according to any one of claims 1 to 4, wherein any one of the composite curved surfaces constituting the shoulder portions located on both sides of the top portion. The distance between the centers of curvature of the pair of curved surfaces is 2A, and the smaller one of the width of one pitch of the concave portion and the width of one pitch of the convex portion in the plurality of the concave and convex portions is 2W, When the raw material thickness is t ₀ and the height of the cross section of the fuel cell separator formed into a corrugated section is H,
(R1 + R2) / A × W × t ₀ /H≧0.15
It is characterized by satisfying the relationship.

  Further, as in claim 6, it is also preferable that the top portion has a shape having a predetermined curvature.

  The fuel cell separator according to any one of claims 1 to 6 is formed by a molding method that does not press the top of the unevenness (the peak or valley of the unevenness), or a molding method that suppresses the pressurization to the top. Is something that can be done. Since such fuel cell separators are suppressed from cracking, distortion, and warping, the contact surface with the MEA, the conductive resistance between the separators, the sealing performance of gas and cooling water, and the assembly of the stack Etc. are easy to secure.

  The invention described in claim 7 is a separator manufacturing apparatus that constitutes a single cell of a fuel cell, further comprising a die for pressing a separator material, and the die is pressed against the separator material. The separator material is provided with a plurality of ribs forming a plurality of grooves, and the ribs are provided with shoulder portions made of a compound curved surface between both side surfaces and the front end surface.

  According to the present invention, since the shoulder portion includes a plurality of curved surfaces, it is possible to suppress the distortion of the upper surface and the lower surface of the separator and to make it flat over a wide area. For example, if a curved surface with a large curvature (small curvature radius) is formed in combination, the shoulder portion can be made smaller by the combined curved surface, and a flat surface other than the shoulder portion can be secured larger (wider). It becomes. Therefore, the contact surface with the MEA, the conductive resistance between the separators, the sealing performance of gas and cooling water, and the assembly property of the stack can be secured.

  The invention according to claim 8 is the separator manufacturing apparatus according to claim 7, wherein the shoulder has a first curved surface having a radius of curvature R1 outside the rib in a cross section of a plane perpendicular to the rib longitudinal direction. And a second curved surface continuous with the first curved surface and having a radius of curvature R2 inside the rib, wherein R1> R2.

  According to the present invention, by setting R1> R2, it is possible to suppress the distortion of the upper surface and the lower surface of the separator and make it flat over a wide area. That is, if R1 <R2 while avoiding breakage and thinning, the width of the flat surface formed between the shoulders may be narrowed, but according to the present invention, a wide flat surface is ensured while suppressing distortion. It becomes possible. Therefore, the contact surface with the MEA, the conductive resistance between the separators, the sealing performance of gas and cooling water, and the assembly property of the stack can be secured.

The invention according to claim 9 is the separator manufacturing apparatus according to claim 8, wherein the first curved surface has a curvature radius R1, the second curved surface has a curvature radius R2, and the material thickness t of the separator material. About ₀
(R1 + R2) / t ₀ > 1
It is characterized by satisfying.

When the ratio of the shoulder portion to the material original thickness t ₀ is 1 or less, the thickness reduction during processing is large, and the possibility of breakage increases. Moreover, the variation in the warp height of the separator material generated by processing becomes large, and it becomes difficult to ensure a predetermined quality. According to the present invention, by setting the above processing conditions, it is possible to prevent cracking and distortion and to ensure the sealing performance and assembling performance of the product.

A tenth aspect of the present invention is the separator manufacturing apparatus according to any one of the seventh to ninth aspects, wherein the separator manufacturing apparatus includes, as the mold, a corrugated mold that molds the separator material into a corrugated shape. And a coining mold for further coining the separator material formed into the corrugated shape, and the groove of the separator material formed by the corrugated mold is along the plate surface of the separator material. The forming length per groove in the direction is l _R , and the groove of the separator material formed by the coining forming die has the forming length per groove in the direction along the plate surface of the separator material. l _C and the ratio of l _R to l _C is
0.98 ≦ l _R / l _C ≦ 1.02
It is characterized by being.

Here, l _R and l _C are the length in the direction along the plate from the tip of the ridge-like convex portion on both sides of the groove to the tip of the adjacent convex portion, that is, the molding length in the direction along the plate surface.

  If the molding ratio is out of the above ratio, the height of the warp (sledge width) of the separator material generated by processing increases, and the shape of the uneven portion may become a drum shape or a drum shape. . As a result, it becomes difficult to ensure the sealing and assembling properties of the product. However, according to the present invention, the sled height can be kept within the limits by setting the molding ratio within the above range, and the sealing and assembling properties of the product. Can be secured.

This will be explained in a little more detail as follows. That is, being out of the range of the molding ratio described above means that the warp height indicated by the symbols S _A and S _B exceeds a certain range. In this case, phenomena such as breakage and buckling occur in the separator. (See FIGS. 6A to 6C). Then, the uneven part is shaped like a drum (see reference numeral 74 'in FIG. 3 (c)) where the central part is slightly swollen, or conversely, the central part is somewhat thin. (See reference numeral 74 ″ in FIG. 3 (c)), but in the present invention, the shape is within the preferred range as described above. It is possible to keep this within the limits.

The invention according to claim 11 is the separator manufacturing apparatus according to any one of claims 8 to 10, wherein the separator material is formed by meshing the ribs with the separator material in between as the mold. A first die to be pressed and a second die; and a distance between the centers of curvature of the second curved surfaces provided on both shoulders of the rib of the first die is 2A. When meshed with the second mold, the distance between the gaps between the ribs of the second mold formed on both sides of the rib of the first mold is W, and the separator material When the material original thickness is t ₀ and the height of the separator material after press working by the first die and the second die is H,
(R1 + R2) / A × W × t ₀ /H≧0.15
It is characterized by satisfying.

The warp height of the separator material generated by processing affects the raw material thickness t ₀ , the uneven channel shape, the shoulder shape, the groove depth, the groove pitch, the height of the corrugated product, and the like. As a result of various studies by the inventors, it has been found that warpage can be minimized by satisfying the above formula. Thereby, the contact surface with MEA, the electrical resistance between separators, the sealing performance of gas and cooling water, and the assembly | attachment property of a stack are securable.

  A twelfth aspect of the present invention is the separator manufacturing apparatus according to any of the seventh to eleventh aspects, wherein the mold slightly bulges in the height direction of the ribs between the adjacent ribs. A bulging portion is provided.

  When the width of the rib top is short, the top of the separator after processing may bulge outward and a flat surface may not be obtained, whereas according to the present invention, by providing the bulging portion on the mold, It becomes possible to make the rear top portion flat.

  According to a thirteenth aspect of the present invention, a separator for manufacturing a single cell separator for a fuel cell is formed by pressing a separator material using a mold having a plurality of ribs to form a plurality of grooves in the separator material. In the manufacturing method, as the rib, pressing is performed using a rib having a shoulder portion formed of a compound curved surface between both side surfaces and a tip surface.

  According to the present invention, by processing the separator with a mold having a shoulder portion constituted by a plurality of curved surfaces, it is possible to suppress distortion of the upper surface and the lower surface of the separator and make it flat over a wide area. Therefore, the contact surface with the MEA, the conductive resistance between the separators, the sealing performance of gas and cooling water, and the assembly property of the stack can be secured.

  According to a fourteenth aspect of the present invention, in the separator manufacturing method according to the thirteenth aspect, the shoulder portion has a first curved surface having a radius of curvature R1 outside the rib in a cross section of a plane perpendicular to the rib longitudinal direction. And a second curved surface continuous with the first curved surface and having a radius of curvature R2 inside the rib, wherein R1> R2.

  According to the present invention, by setting R1> R2, it is possible to suppress the distortion of the upper surface and the lower surface of the separator and make it flat over a wide area. Therefore, the contact surface with the MEA, the conductive resistance between the separators, the sealing performance of gas and cooling water, and the assembly property of the stack can be ensured.

According to a fifteenth aspect of the present invention, in the separator manufacturing method according to the fourteenth aspect, a curvature radius R1 of the first curved surface, a curvature radius R2 of the second curved surface, and a material original thickness t of the separator material. About ₀
(R1 + R2) / t ₀ > 1
The processing is performed under the following conditions.

When the ratio of the shoulder portion to the material original thickness t ₀ is 1 or less, the thickness reduction during processing is large, and the possibility of occurrence of breakage may increase. Moreover, the variation in the warp height of the separator material generated by processing increases, and it may be difficult to ensure a predetermined quality. According to the present invention, by setting the above processing conditions, it is possible to prevent cracking and distortion and to ensure the sealing performance and assembling performance of the product.

The invention according to claim 16 is the separator manufacturing method according to any one of claims 13 to 15, wherein the separator material is corrugated using the corrugated mold as the mold, and then the mold is molded. The separator material formed in the corrugated mold is further coined using a coining mold as the groove of the separator material formed by the corrugated mold, the direction along the plate surface of the separator material a molded length l _R per one trench in the groove of the separator material molded by the coining mold is shaped length per one trench in the direction along the plate surface of the separator material is l _C , and the ratio of l _R to l _C is
0.98 ≦ l _R / l _C ≦ 1.02
The processing is performed under the following conditions.

Here, l _R and l _C are the length in the direction along the plate from the tip of the ridge-like convex portion on both sides of the groove to the tip of the adjacent convex portion, that is, the molding length in the direction along the plate surface.

  If the molding ratio is out of the above ratio, the warp height of the separator material generated by processing increases, and the target dimension in the groove width direction and the dimension in the groove direction become a drum shape or a drum shape, ensuring product sealing and assembling properties. It becomes difficult. According to the present invention, by setting the molding ratio within the above range, the warp height can be kept within the limit, and the sealing performance and assembly performance of the product can be ensured.

The invention according to claim 17 is the separator manufacturing method according to any one of claims 14 to 16, wherein the first mold and the second mold are used as the mold, and the first and second molds are used. The separator material is pressed by engaging the ribs with the separator material in between, and between the curvature centers of the second curved surfaces provided on the rib shoulders of the first mold A gap between the ribs of the second mold formed on both sides of the ribs provided in the first mold when the distance is 2A and the first mold and the second mold are engaged with each other. When the distance between is W, the material original thickness of the separator material is t ₀ , and the height of the separator material after pressing by the first mold and the second mold is H,
(R1 + R2) / A × W × t ₀ /H≧0.15
The processing is performed under the following conditions.

The warp height of the separator material produced by processing affects the original thickness t ₀ , the shape of the uneven channel, the shape of the shoulder, the groove depth, the groove pitch, the height of the corrugated product, etc. As a result of various studies, they found that the warp can be minimized by satisfying the above equation. Thereby, the contact surface with MEA, the electrical resistance between separators, the sealing performance of gas and cooling water, and the assembly | attachment property of a stack are securable.

  According to an eighteenth aspect of the present invention, in the separator manufacturing method according to any one of the thirteenth to seventeenth aspects, the mold slightly bulges in the height direction of the ribs between the adjacent ribs. A bulging portion is provided.

  When the width of the rib top is short, the top of the separator after processing may swell outward and a flat surface may not be obtained. According to the present invention, it is possible to make the top after processing flat by providing the bulging portion in the mold.

  According to the fuel cell separator, the separator manufacturing apparatus, and the separator manufacturing method according to the present invention, it is possible to suppress the occurrence of cracks, distortion, and warpage of the separator, and to ensure high-quality fuel by ensuring the sealing performance and assembling performance of the product. A battery can be obtained.

  Hereinafter, the configuration of the present invention will be described in detail based on an example of an embodiment shown in the drawings.

  1 to 12 show an embodiment of the present invention. The fuel cell separator according to the present invention (hereinafter, also simply referred to as a separator) is subjected to coining after the separator material is corrugated and formed into a corrugated shape with a constant pitch. Is formed. In such a fuel cell separator, shoulder portions (curved or curved portions) are located on both sides of the top of the unevenness, and in this embodiment, corrugated (see FIG. 7 etc.), coining After the process of (see FIG. 8), such a shoulder is formed by combining at least two curved surfaces of a curved surface with a radius of curvature R1 and a curved surface with a radius of curvature R2 (R1 ≠ R2) (FIG. 8). 4 etc.). Hereinafter, a fuel cell separator, a separator manufacturing apparatus, and a separator manufacturing method according to preferred embodiments of the present invention will be described with reference to the accompanying drawings. First, the structure of a fuel cell to which the separator manufacturing apparatus and separator manufacturing method according to the present embodiment are applied will be described.

  This fuel cell is formed by laminating a plurality of single cells, which are the minimum power generation unit, and by integrally joining the parts constituting the single cell or between the single cells with a resin mold, the single cell and This is an improvement in fuel cell productivity. Hereinafter, a solid polymer fuel cell (PEFC) suitable for in-vehicle use will be described as an example.

  As shown in FIG. 1, the fuel cell 1 includes a stack body 3 in which a plurality of single cells 2 are stacked, and the output terminals 5 are sequentially attached to the outside of the single cells 2 and 2 located at both ends of the stack body 3. The current collector plate 6, the insulating plate 7, and the end plate 8 are each arranged. In the fuel cell 1, for example, a tension plate (not shown) provided so as to bridge between both end plates 8, 8 is bolted to each end plate 8, 8, so that the single cells 2 are stacked in the stacking direction. A predetermined compressive force is applied.

  As shown in FIG. 2, the single cell 2 includes an MEA 11 and a pair of separators 12 a and 12 b that sandwich the MEA 11, and has a laminated form as a whole. The MEA 11 and the separators 12a and 12b are substantially planar parts and have a rectangular outer shape in plan view. The outer shape of the MEA 11 is slightly smaller than the outer shape of the separators 12a and 12b. . The MEA 11 and the separators 12a and 12b are molded by a molding resin 40 together with the first seal members 13a and 13b at the peripheral portions therebetween. A second seal member 13c is provided between the separators 12a and 12b of the adjacent single cells 2 and 2.

  The MEA 11 includes an electrolyte membrane 21 made of an ion exchange membrane made of a polymer material and a pair of electrodes 22a and 22b (cathode and anode) sandwiching the electrolyte membrane 21 from both sides, and has a laminated form as a whole. . The electrolyte membrane 21 is formed slightly larger in size than the electrodes 22a and 22b. The electrodes 22a and 22b are joined to the electrolyte membrane 21 by, for example, a hot press method with the peripheral edge portion 24 left.

  The electrodes 22a and 22b are made of, for example, a porous carbon material (diffusion layer) bound with a catalyst such as platinum. One electrode 22a (cathode) is supplied with an oxidizing gas such as air or an oxidant, and the other electrode 22b (anode) is supplied with hydrogen gas as a fuel gas. These two gases cause an electrochemical reaction in the MEA 11 and the single cell 2 obtains an electromotive force.

  Each separator 12a, 12b is made of a gas impermeable conductive material. The base material of the separators 12a and 12b of the present embodiment is formed of a plate-like metal, and the surface on the electrode side of the base material is coated with a film having excellent corrosion resistance.

  As will be described later, the separators 12a and 12b are formed such that a plurality of irregularities are provided on the front and back surfaces by press-molding the portions facing the electrodes 22a and 22b, and the cross section is wavy. The plurality of protrusions and recesses extend in parallel and straight, and define a gas flow path 31 a for oxidizing gas, a gas flow path 31 b for hydrogen gas, and a cooling water flow path 32.

  Specifically, a plurality of straight oxidizing gas flow paths 31a are formed on the inner surface of the separator 12a on the electrode 22a side, and a straight cooling water flow path is formed on the opposite outer surface. A plurality of 32 are formed. Similarly, a plurality of straight hydrogen gas flow paths 31b are formed on the inner surface of the separator 12b on the electrode 22b side, and a straight cooling water flow path 32 is formed on the opposite outer surface. A plurality are formed.

  And the two gas flow paths 31a and 31b in the single cell 2 extend in parallel in the same direction, and are arrange | positioned so that it may oppose without shifting position on both sides of MEA11. Further, in the two adjacent single cells 2 and 2, the outer surface of the separator 12a of one single cell 2 and the outer surface of the separator 12b of the adjacent single cell 2 are attached to each other, and the cooling water flow paths 32 of both are communicated. To do. The separator 12a and the separator 12b of the adjacent single cells 2 and 2 are molded with a molding resin 40 at a peripheral portion between them.

  At one end of each of the separators 12a and 12b, a manifold on the inlet side of the oxidizing gas, a manifold on the inlet side of the hydrogen gas, and a manifold on the inlet side of the cooling water are formed penetrating. Similarly, a manifold on the outlet side of the oxidizing gas, a manifold on the outlet side of the hydrogen gas, and a manifold on the outlet side of the cooling water are formed through the other ends of the separators 12a and 12b. Each fluid is supplied to each of the oxidizing gas passage 31a, the hydrogen gas passage 31b, and the cooling water passage 32 through each inlet manifold, and is discharged from each passage to each outlet manifold.

  FIG. 3 is a diagram illustrating a procedure for manufacturing the separators 12a and 12b.

The code | symbol 70 of Fig.3 (a) is a separator material which is the object of shaping | molding processes, such as press work. The thickness (raw material thickness) of the separator material 70 before processing is t ₀ . The separator material 70 is pressed by a mold, and the central portion (groove formation region 74) facing the electrodes 22a and 22b is processed into a corrugated product 71 (see FIG. 3B). ). The width of the groove forming region 74 formed in the corrugated is B _R.

Further, the corrugated molded product 71 of (b) is coined and becomes a coining process product 72 of (c). The width of the groove forming region 74 after coining is B _C , the length is C, and the warp height of the plate produced by processing is S _A in the longitudinal direction and S _B in the width direction. .

  Further, the separators 12a and 12b of (d) are completed by punching out manifold holes. The manifold hole may be punched simultaneously with coining, or the outer shape may be punched.

  Next, the waveform processing in (a) to (b) and the coining molding in (b) to (c) will be described in detail.

  As shown in FIG. 4, the wave forming process is performed by sandwiching the separator material 70 using a pair of upper and lower molds (wave forming molds) 80 and 81 and pressing the separator material 70. The upper mold (second mold) 80 is formed with convex portions (ribs) 80a and concave portions 80b alternately, and the lower mold (first mold) 81 is formed with respect to the upper convex portions 80a and concave portions 80b. The concave portions 81a and the convex portions (ribs) 81b that are meshed with each other having a gap are alternately formed. These convex portions 80a and 81b and concave portions 80b and 81a extend in the longitudinal direction of the separator material 70 (the direction perpendicular to the paper surface in FIG. 4).

  In the upper mold 80 and the lower mold 81, convex portions 80a and 81b and concave portions 80b and 81a are repeatedly provided at a constant pitch P, and the configuration shown in the range of P / 2 in FIG. 4 is symmetrical. Are repeatedly provided. P is a formation interval (groove pitch) of the convex portions 80a and 81b along the width direction of the separator material 70 (left and right direction in the figure), that is, a repeating unit of a set of concave and convex portions.

The convex part 80a and the convex part 81b are provided with flat parts 84 and 85 at the top end face of the top part, and both side faces have side walls 86 and 87 substantially perpendicular to the flat parts 84 and 85. A boundary portion between the side walls 86 and 87 and the flat portions 84 and 85 is a shoulder portion 88 that is smoothly continuous. The shoulder portion 88 has a curved surface (first curved surface) 88a having a curvature radius R1 _{R and} a curved surface (second surface) having a curvature radius R2 _R that are smoothly continuous with each other in a cross section of a plane perpendicular to the longitudinal direction of the convex portions 80a and 81b. The curved surface) 88b is a composite R shape. The side walls 86 and 87 are smoothly connected to the curved surface 88a, and are further continuously connected to the curved surface 88b and the flat portions 84 and 85. In the following description, the suffix R is added to parameters such as the radii R1, R2 and the like during wave forming, and the suffix C is added during coining.

Each symbol in the figure will be described as follows. That is,
A _R is the half width of the distance between the centers of curvature of the curved surface 88b provided on the convex portion 81b of the lower mold 81,
W is a gap between the convex portions 80a of the upper mold 80 formed on both sides of the convex portions 81b of the lower mold 81 when the upper mold 80 and the lower mold 81 are engaged with each other. distance,
l _R / 2 is a length dimension (molding length) along the plate surface of the corrugated molded product 71 formed within the width of the half pitch P / 2,
H _R is corrugated height of the molded article 71 after the corrugating,
It is. The R1 _R , R2 _R , A _R , W, and H _R are set so as to satisfy the following conditions.

R1 _R > R2 _R
(R1 _R + R2 _R ) / t ₀ > 1
(R1 _R + R2 _R ) / A _R × W × t ₀ / H _R ≧ 0.15
In addition, the code | symbol W shown here represents the distance between the clearance gaps 89 between the convex part 80a of the upper metal mold | die 80 formed in the both sides of the convex part 81b of the lower metal mold | die 81 as above-mentioned. However, when this is applied to a corrugated molded article (fuel cell separator) 71 after molding, it can also be expressed as follows. That is, among the plurality of irregularities formed, the width occupied by the concave portion (for example, 81a) is, for example, 2W ', the width occupied by the convex portion (for example, 81b) is, for example, 2W, and the sum of these 2W' and 2W is one pitch This W when it is assumed to be equal to the length P corresponds to the W described here. That is, W in the above formula is W, which is a half value when the length of one convex portion (width of one convex portion) is set to 2W. In this case, if the width of one pitch of the concave portion is different from the width of one pitch of the convex portion, the smaller value usually corresponds to 2W.

The upper mold 80 and the lower mold 81 are configured under such conditions, and the separator material 70 is pressed. A plurality of grooves are formed in a wave shape in the groove forming region 74 due to the unevenness provided in each mold 80, 81. After pressing, the plate thickness is not constant, the plate thickness at the convex portion 81b of the lower mold 81 is t _u , and the plate thickness at the convex portion 80a of the upper mold 80 is t _B.

  Further, during the main molding, the recesses 80b and 81a of the upper mold 80 and the lower mold 81 are not in contact with the separator material 70, and the top of the separator material 70 is not pressurized.

<Coining molding>
As shown in FIG. 5, coining is performed by sandwiching a corrugated product 71 using a pair of upper and lower molds (coining molds) 90 and 91 and pressing. The upper mold (second mold) 90 is formed with convex portions (ribs) 90a and concave portions 90b alternately, and the lower mold (first mold) 91 is formed with respect to the upper convex portions 90a and concave portions 90b. The concave portions 91a and the convex portions (ribs) 91b that are meshed with each other having a gap are alternately formed. These convex portions 90a and 91b and concave portions 90b and 91a correspond to the corrugated shape formed on the corrugated product 71 in the corrugating process, and the longitudinal direction of the corrugated product 71 (perpendicular to the paper surface in the figure). Extending in the right direction).

  The upper mold 90 and the lower mold 91 are provided with convex portions 90a and 91b and concave portions 90b and 91a repeatedly, and the configuration shown in the range of the half pitch P / 2 in FIG. 5 is symmetrically repeated. Is provided.

The convex part 90a and the convex part 91b are provided with flat parts 94 and 95 on the top end face of the top part, and both side faces have side walls 96 and 97 substantially perpendicular to the flat parts 94 and 95. The boundary between the side walls 96, 97 and the flat portions 94, 95 is a smoothly continuous curved surface (shoulder 98). The shoulder 98 has a curved surface (first curved surface) 98a having a radius of curvature R1 _{C and} a curved surface (second curved surface) having a radius of curvature R2 _C that are smoothly continuous with each other in a cross section of a plane perpendicular to the longitudinal direction of the convex portions 90a and 91b. Of the curved surface) 98b. The side walls 96 and 97 are smoothly connected to a curved surface 98a having a curvature radius R1 _C, and are further continuously connected to the curved surface 98b and the flat portions 94 and 95.

In FIG.
A _C is a half width of the distance between the centers of curvature of the curved surface 98b provided on the convex portion 91b of the lower mold 91;
l _C / 2 is a length dimension (molding length) along the plate surface of the coining process product 72 formed within the width of the half pitch P / 2,
H _C is the height of the coining process products 72 after coining molding,
H _G is the groove depth,
It is. R1 _C , R2 _C , A _C , W, H _{C and the} like are set so as to satisfy the following conditions.

R1 _C > R2 _C
(R1 _C + R2 _C ) / t ₀ > 1
(R1 _C + R2 _C ) / A _C × W × t ₀ / H _C ≧ 0.15
(R1 _R + R2 _R ) / (R1 _C + R2 _C ) ≧ 2
0.98 ≦ l _R / l _C ≦ 1.02
Under these conditions, the upper mold 90 and the lower mold 91 are configured, and the corrugated product 71 is pressed to form a coining process product 72. The grooves formed in a wave shape by the corrugation are further deformed by coining.

According to the present embodiment, 0.9985 ≦ B _R / B _C ≦ 1.0015 as shown in FIGS. 6B and 6C by performing wave forming and coining forming under the above processing conditions.
The molded article can be obtained and distortion can be suppressed.

  Specifically, the following actions are obtained according to each condition.

(1) Set the parameters as R1 _R > R2 _R
R1 _C > R2 _C
By doing so, it is possible to flatten the upper surface 105 and the lower surface 106 of the completed separators 12a and 12b over a wide area. Therefore, it is possible to ensure the contact surface with the MEA 11, the conductive resistance between the separators 12a and 12b, the sealing properties of gas and cooling water, and the assembly property of the stack.

(2) The parameter is 0.98 ≦ l _R / l _C ≦ 1.02.
By doing so, the sled height can be kept within the limits.

When the molding ratio is out of the above range, the warp height S _H (S _A , S _B ) exceeds the limit as shown in FIGS. 6A to 6C, and as shown in FIG. The target dimension B _{C in} the groove width direction and the dimension _{C in} the groove direction become the drum shape 74 ′ and the drum shape 74 ″, which makes it difficult to ensure the sealing performance and assembling performance of the product.

  In addition, when the above ratio is smaller than the predetermined range, the separators 12a and 12b are easily broken, and when larger than the predetermined range, the separator 12a and 12b are easily buckled.

According to the present embodiment, by being within the above molding ratio,
0.9985 ≦ B _R / B _C ≦ 1.0015
Thus, the groove width of the molded product is within a predetermined range, the warp height (S _A , S _B ) can be kept within the limit, and the sealing performance and assembling performance of the product can be ensured.

Note that at least 0.98 ≦ l _R / l _C ≦ 1.02 should be satisfied, but by further satisfying 0.9985 ≦ B _R / B _C ≦ 1.0015, distortion can be more effectively suppressed. Can do.

(3) Change the parameter to (R1 _R + R2 _R ) / t ₀ > 1
(R1 _C + R2 _C ) / t ₀ > 1
By doing, suppression of a fracture | rupture and ensuring of thickness are implement | achieved.

When the ratio of the shoulder portion to the raw material thickness t ₀ is 1 or less, the thickness reduction mainly by the wave forming becomes large. For this reason, it is difficult to ensure breakage in coining molding and to secure the minimum wall thickness (for example, 0.04 mm or more) necessary for the product. In addition, mold manufacturing tolerance in coining molding is added, and the warp height (S _A , S _B ) Variations increase and it becomes difficult to ensure a predetermined quality. According to this embodiment, by setting it as said process conditions, a crack and distortion can be prevented and the sealing performance of a product and assembly | attachment property can be ensured.

(4) Parameter
(R1 _R + R2 _R ) / A _R × W × t ₀ / H _R ≧ 0.15
(R1 _C + R2 _C ) / A _C × W × t ₀ / H _C ≧ 0.15
By doing so, warpage can be minimized.

The warp height (S _A , S _B ) of the product depends on the original thickness t ₀ , uneven channel shape, shoulder R shape, groove depth H _G , groove pitch P, corrugated product height H _R , etc. However, as a result of various investigations, the above formula is satisfied, and further, by a molding method in which the top of the separator material is not pressurized during wave forming, warpage can be minimized, the contact surface with the MEA 11, the separator 12a, The conductive resistance between 12b, the sealing performance of gas and cooling water, and the assembly property of the stack can be ensured. In addition, although described here as a molding method in which the top is not pressurized, it is more preferable to press the top without reducing the thickness of the top in coining molding. The pressurization in this case mainly applies bending and compression. In such a case, the thickness is not crushed correctively.

(5) Parameter is (R1 _R + R2 _R ) / (R1 _C + R2 _C ) ≧ 2
By doing so, it is possible to flatten the upper surface 105 and the lower surface 106 of the completed separators 12a and 12b over a wide area. Therefore, it is possible to ensure the contact surface with the MEA 11, the conductive resistance between the separators 12a and 12b, the sealing properties of gas and cooling water, and the assembly property of the stack.

  As described above, according to the separator manufacturing apparatus and the separator manufacturing method of the present embodiment, generation of cracks, distortion, and warpage can be suppressed, and a high-quality fuel cell can be ensured by ensuring product sealing performance and assembly performance. Can be obtained. This will be described in more detail as follows.

  That is, (a) when the separator material 70 is supported by, for example, a blank holder and the upper mold 80 is used to roughly form the lower mold 81 with, for example, an elastic pad, the periphery of the blank holder, the vicinity thereof, or the shoulder 88 ( Or 98), the separator may be thin. In addition, in the case of a product with a fine uneven pitch P and a large standing surface, the second molding (second process) is also over-molded. It can be difficult. For example, the outer peripheral portion has a flat shape (here, “the outer peripheral portion has a flat shape” means that, for example, the outer portion of the rectangular groove forming region 74 shown in FIG. 3D is formed flat. If the overhang is formed in the center by elastic body or hydraulic pressure, the bending moment due to the overhang force at the corner, edge and center is different, and the R (curvature radius) of the shoulder 88 is small. Then, it can be said that one of the reasons is that the local elongation of the material becomes large and molding becomes difficult. On the other hand, according to the separator manufacturing technology according to the present embodiment that suppresses the generation of cracks, distortions, and warpage, or the fuel cell separator manufactured by the separator manufacturing technology, it is possible to solve these molding problems. Is possible.

  (B) In a general molding process, the peripheral part parallel to the longitudinal direction of the gas flow path is fixed, the peripheral part orthogonal to the longitudinal direction is locked with a mold, and the flow path is press-molded. Since a tensile force in the same direction as the rolling direction is applied by this, when the orthogonal peripheral part has a distribution shape, inter-channel dimension retention and shape retention with that shape becomes difficult. In addition, when the peripheral flow path portion parallel to the longitudinal direction of the gas flow path becomes a drum shape or a drum shape as described above, the peripheral portion parallel to the longitudinal direction is Since it is fixed, the distortion may not be eliminated. Explaining the above in a little more detail, for example, after rolling the concavo-convex groove, a predetermined portion (in this case, the portion that is the concavo-convex groove) is pressed and constrained in the subsequent process, and the tensile force is the same as the rolling direction. However, in this case, a difference in distortion occurs between the peripheral portion perpendicular to the longitudinal direction of the concave and convex groove portion, and adjustment thereof is necessary. The initial shape may also change. In addition, the peripheral portion perpendicular to the longitudinal direction of the concave and convex groove portion is formed into a drum shape or a drum shape due to a stress difference (a difference in springback amount) of the shoulder R portion perpendicular to the longitudinal direction of the groove portion during general molding. Although warpage may occur, if the peripheral portion orthogonal to the longitudinal direction of the groove is constrained, a uniform amount of deformation cannot be applied to the entire groove, and it may be difficult to stabilize the strain. More specifically, the shoulder R part has a large tensile stress during molding, and if the shoulder R part stretches due to residual stress during unloading (when the mold is opened), it springs back due to compressive stress, and its stress balance Causes warping. Alternatively, the compressive stress at the time of molding is large, and the tensile stress acts at the time of release, and warpage occurs due to the magnitude and unbalance of the force at this time. When the warp orthogonal peripheral part is restrained at the time of or after the occurrence of such warpage, it becomes difficult to give a uniform deformation amount to the entire groove part. That is, tensile stress acts at the center in the groove width direction, but similar stress is not applied at the constrained portion, and the difference becomes distortion, making it difficult to stabilize the warp. In this regard, according to the technique of the present embodiment, as described above, it is possible to form a separator that is excellent in the retention of dimensions and shape by suppressing the drum shape or the drum shape.

  (C) At the time of molding, since a certain amount of rolling is applied to the processed part and the surrounding flat part in the center of the concave and convex grooves, the shape of the concave and convex grooves is different or the thickness of the material varies. If there is, the amount of rolling in the groove direction is distorted due to the difference in the thickness between the concave and convex groove near the center and the surrounding flat part, that is, the waviness is generated, and the deflection of the roll shaft is added. It is difficult to do. In other words, when rolling is applied to the uneven portion of a thin plate, a compressive stress is always generated in the uneven portion, and the amount of deformation and residual stress due to volume fluctuations (directions perpendicular to the plate thickness direction, rolling direction, and rolling direction) corresponding to this. However, this is a difference in the amount of distortion around the concavo-convex part, leading to the occurrence of warpage and excess meat. In this respect, according to the technique of the present embodiment, it is possible to suppress the occurrence of cracks, distortion, and warpage in the separator as described above, and thus it is possible to eliminate such problems.

  (D) When the thickness of the separator material is, for example, about 0.1 mm and the pitch of the unevenness is small, if the curvature radius R of the shoulder portion is set to a certain small value, the shoulder portion breaks at an early stage during the molding process. In some cases, a predetermined groove depth cannot be obtained, and a flat portion at the top cannot be secured. In addition, when the groove shape of the concavo-convex part is asymmetrical and the rolling amount and deformation amount are the same, the thickness of the top part and the shoulder part is different, resulting in a difference in deformation amount and a difference in stress strain, resulting in a smooth product. It may disappear. In this regard, according to the technique of the present embodiment, as described above, it is possible to suppress the occurrence of cracks, distortion, and warpage in the separator, and thus it is possible to solve such a problem.

  (E) In the fuel cell separator, when shoulders having a constant radius of curvature are provided at the upper and lower bases, if the area or region of the flat part is increased, the amount of coining at the top is increased. On the other hand, if the coining amount of the upper bottom part and the lower bottom part is not made comparable, there is a difference in distortion amount, and it may be difficult to eliminate the warp. That is, as described above, warping occurs due to the stress acting on the shoulder R portion during molding, but this point, particularly the coining amount (bending compression amount) at the shoulder R portion must be the same. There is a case where a difference in residual stress is generated in the shoulder R, and the difference leads to generation of warpage. In particular, in the case of an ultrathin plate or foil, such a problem tends to become remarkable. In this respect, according to the technique of the present embodiment, the shape of the shoulder R portion is substantially the same (see, for example, FIG. 5), and the balance of the residual stress can be ensured. Such a problem can be solved because generation of distortion, warpage, and warpage can be suppressed.

  The above-described embodiment is an example of a preferred embodiment of the present invention, but is not limited thereto, and various modifications can be made without departing from the scope of the present invention. Hereinafter, modifications of the above-described embodiment will be described.

  As shown in FIG. 7, a bulging portion 100 that slightly bulges with a curvature ρ1 is provided in the concave portion 90b of the upper mold 90 used for coining molding. The convex portion 91 b of the lower mold 91 is provided with a depressed portion 102 that faces the bulging portion 100 and is slightly inwardly concave with a curvature ρ1.

  Further, a bulging portion 101 that slightly bulges with a curvature ρ2 is provided in the concave portion 91a of the lower mold 91. The convex portion 90 a of the upper mold 90 is provided with a depressed portion 103 that faces the bulging portion 101 and is slightly recessed inward with a curvature ρ2.

The bulge width of the bulge portion 100 and the depression width of the depression portion 102 are h ₁ , and the bulge width of the bulge portion 101 and the depression width of the depression portion 103 are h ₂ . If not provided the bulged portion 100, 101 and the depressions 102 and 103, the size and dimensions A _C of the shoulder portion 98 is small, the separator 12a after molding, the upper surface 105 and lower surface 106 of 12b upper surface 105 of FIG. 8 It swells like 'and the lower surface 106'. By providing the bulging portions 100 and 101 and the depressed portions 102 and 103 in the molds 90 and 91 as described above, the upper surface 105 and the lower surface 106 of the separators 12a and 12b after molding are finished flat as shown in FIG. be able to. Therefore, it is possible to ensure the contact surface with the MEA 11, the conductive resistance gas and the cooling water between the separators 12a and 12b, and the stacking property.

  In the above example, the bulging portions 100 and 101 and the corresponding recessed portions 102 and 103 are provided on both the convex portion 90a of the upper mold 90 and the convex portion 91b of the lower mold 91. It may be provided only on one side. For example, when the width of the convex part 90a of the upper mold 90 is sufficiently wide, the bulging part 101 of the lower mold 91 and the depressed part 103 of the upper mold 90 need not be provided. Further, the depressions 101 and 102 need not be provided.

In the above embodiments, the upper mold 80 and the lower mold 81 and the shoulders 88 and 98 of the upper mold 90 and the lower mold 91 have the same shape, but they may be different. For example, both the convex portion 80 a of the upper mold 80 and the convex portion 81 b of the lower mold 81 have curved surfaces having the curvature radii R 1 _R and _R 2 _R , but the shoulder curvature radius of the upper mold 80 and the lower mold 81 The shoulder radius of curvature may be different.

It is a perspective view of a fuel cell shown as one embodiment of the present invention. It is sectional drawing of the fuel cell, and is a figure which shows the structure of two adjacent single cells. (A)-(d) is the three-plane figure shown about the procedure which processes the separator of a fuel cell, respectively. It is the fragmentary sectional view shown about the state which inserts separator material with a metal mold | die and press-processes. It is the fragmentary sectional view shown about the state which pinches | molds a separator material with a metal mold | die. It is the figure shown about the parameter conditions in the case of wave shape shaping | molding and coining shaping | molding. It is the fragmentary sectional view shown about the state which press-processes using the metal mold | die shown as a modification. It is the fragmentary sectional view which showed the separator after processing with the metal mold | die.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Fuel cell, 2 ... Single cell, 12, 12b ... Separator, 70 ... Separator material, 80 ... Upper metal mold | die (corrugated mold, 2nd type | mold), 80a ... Projection (rib), 81 ... Lower part Mold (corrugated mold, first mold), 81b ... convex portion (rib), 88 ... shoulder, 88a ... curved surface (first curved surface), 88b ... curved surface (second curved surface), 90 ... Upper mold (coining mold, second mold), 90a ... convex (rib), 91 ... lower mold (coining mold, first mold), 91b ... convex (rib), 98 ... Shoulder, 98a ... curved surface (first curved surface), 98b ... curved surface (second curved surface), 100, 101 ... bulged portion

Claims (18)

In the fuel cell separator formed by coining after forming the corrugated separator material into a corrugated section,
A fuel cell separator comprising a curved surface in which shoulder portions located on both sides of the top of the unevenness are combined.   2. The fuel according to claim 1, wherein the combined curved surface includes at least a first curved surface having a curvature radius R <b> 1 and a second curved surface having a curvature radius R <b> 2, and R <b> 1> R <b> 2. Battery separator. The forming length which is the length along the corrugated cross section for one pitch among the plurality of irregularities formed is l _R ,
When the coining length, which is the length along the molding surface for one pitch among the irregularities in the corrugating mold used for the coining process, is 1 _C ,
The ratio of l _R to l _C is
0.98 ≦ l _R / l _C ≦ 1.02
The fuel cell separator according to claim 1, wherein the relationship is satisfied. The first curved surface of curvature radius R1, the second curved surface of radius of curvature R2, and, for the material Motoatsu t ₀ of the separator material,
(R1 + R2) / t ₀ > 1
The fuel cell separator according to claim 2, wherein the relationship is satisfied. The distance between the centers of curvature of any of the pair of curved surfaces among the composite curved surfaces constituting the shoulder portions located on both sides of the top portion is 2A,
The smaller one of the width of one pitch of the concave portion and the width of one pitch of the convex portion in the plurality of the concave and convex portions formed is 2W,
The material original thickness of the separator material is t ₀ ,
When the height of the cross section of the fuel cell separator formed into a corrugated cross section is H,
(R1 + R2) / A × W × t ₀ /H≧0.15
The fuel cell separator according to claim 1, wherein the relationship is satisfied.   The fuel cell separator according to any one of claims 1 to 5, wherein the top portion has a shape having a predetermined curvature. In a separator manufacturing apparatus that constitutes a single cell of a fuel cell,
A mold for pressing the separator material, the mold includes a plurality of ribs that are pressed against the separator material to form a plurality of grooves in the separator material;
The separator manufacturing apparatus according to claim 1, wherein the rib is provided with a shoulder portion composed of a compound curved surface between both side surfaces and the front end surface.   In the cross section of the plane perpendicular to the rib longitudinal direction, the shoulder portion is positioned on the outer side of the rib and has a first curved surface with a radius of curvature R1, and on the inner side of the rib continuously with the first curved surface, the curvature. The separator manufacturing apparatus according to claim 7, further comprising: a second curved surface having a radius of R 2, wherein R 1> R 2. The first curved surface of curvature radius R1, the second curved surface of radius of curvature R2, and, for the material Motoatsu t ₀ of the separator material,
(R1 + R2) / t ₀ > 1
The separator manufacturing apparatus according to claim 8, wherein: The separator manufacturing apparatus includes, as the mold, a corrugated mold that molds the separator material into a corrugated shape, and a coining mold that further coins the separator material molded into the corrugated shape,
The groove of the separator material formed by the corrugating mold has a forming length of 1 _R per groove in the direction along the plate surface of the separator material,
Groove of the separator material molded by the coining mold is shaped length per one trench in the direction along the plate surface of the separator material is l _C, the ratio of the l _R and l _C is,
0.98 ≦ l _R / l _C ≦ 1.02
The separator manufacturing apparatus according to any one of claims 7 to 9, wherein The mold includes a first mold and a second mold that press the separator material by engaging the ribs with the separator material in between.
The distance between the centers of curvature of the second curved surface provided on both shoulders of the rib of the first mold is 2A,
When the first mold and the second mold are engaged with each other, the distance between the gaps between the ribs of the second mold formed on both sides of the rib included in the first mold is determined. W,
The material original thickness of the separator material is t ₀ ,
And when the height of the separator material after press working by the first mold and the second mold is set to H,
(R1 + R2) / A × W × t ₀ /H≧0.15
The separator manufacturing apparatus according to claim 8, wherein:   12. The separator manufacture according to claim 7, wherein the mold includes a bulging portion that slightly bulges in the height direction of the rib between the adjacent ribs. apparatus. In a separator manufacturing method for manufacturing a separator for a single cell of a fuel cell by forming a plurality of grooves in the separator material by pressing a separator material using a mold having a plurality of ribs,
The separator manufacturing method characterized by performing press work using the rib provided with the shoulder part which consists of a compound curved surface between both side surfaces and a front end surface as said rib.   The shoulder has a first curved surface having a radius of curvature R1 on the outer side of the rib and a second curved surface having a radius of curvature R2 on the inner side of the rib in a cross section of the plane perpendicular to the longitudinal direction of the rib. The separator manufacturing method according to claim 13, wherein R1> R2. The first curved surface of curvature radius R1, the second curved surface of radius of curvature R2, and, for the material Motoatsu t ₀ of the separator material,
(R1 + R2) / t ₀ > 1
The separator manufacturing method according to claim 14, wherein the processing is performed under the conditions of: After corrugating the separator material using the corrugating mold as the mold, further coining the separator material formed into the corrugated mold using the coining mold as the mold,
The groove of the separator material formed by the corrugating mold has a forming length of 1 _R per groove in the direction along the plate surface of the separator material,
Groove of the separator material molded by the coining mold is shaped length per one trench in the direction along the plate surface of the separator material is l _C, the ratio of the l _R and l _C is,
0.98 ≦ l _R / l _C ≦ 1.02
The separator manufacturing method according to claim 13, wherein the processing is performed under the following conditions. A first mold and a second mold are used as the mold, and the separator material is pressed by sandwiching the separator material between the first and second molds and meshing the ribs with each other. ,
The distance between the centers of curvature of the second curved surface provided on both shoulders of the rib of the first mold is 2A,
When the first mold and the second mold are engaged with each other, the distance between the gaps between the ribs of the second mold formed on both sides of the rib included in the first mold is determined. W,
The material original thickness of the separator material is t ₀ ,
And when the height of the separator material after press working by the first mold and the second mold is set to H,
(R1 + R2) / A × W × t ₀ /H≧0.15
The separator manufacturing method according to any one of claims 14 to 16, wherein the processing is performed under the conditions of: The separator production according to any one of claims 13 to 17, wherein the mold includes a bulging portion that slightly bulges in the height direction of the rib between the adjacent ribs. Method.

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