Mold and composite member for electrochemical device

Abstract

The present invention addresses the problem of providing: a mold which has high durability and is capable of suppressing burrs from a gasket; and a composite member for an electrochemical device. This mold (5) is provided with a first mold (5D) and a second mold (5U). A base material (2) is disposed in the first mold (5D). The second mold (5U) is disposed so as to face the first mold (5D) in the Y direction, and has a cut-off part (50) and a cavity recess part (51) that is disposed on the inner side of the cut-off part (50) in the X-direction and that partitions a cavity (5M) for molding a gasket (4). The cut-off part (50) has: a planar top surface (500) that protrudes toward the base material (2) side with respect to a parting line (PL) and extends in the X direction; a protruding inner side surface (501) that is disposed on the inner side of the top surface (500) in the X-direction; and a protruding outer side surface (502) that is disposed on the outer side of the top surface (500) in the X-direction. The width (W2) in the X-direction between the protruding inner side surface (501) and the protruding outer side surface (502) narrows in the direction from the parting line (PL) toward the top surface (500).

Description

Composite materials for molds and electrochemical devices

[0001] The present disclosure relates to an insert molding die used when molding a gasket onto a substrate, and a composite member for an electrochemical device manufactured using the die.

[0002] Patent Document 1 discloses a mold for molding gaskets that can suppress the generation of burrs. The mold is used when molding gaskets for fuel cell components (such as separators). The mold includes an upper mold and a lower mold. A gasket molding area and a seal groove are recessed into the lower surface (mold surface) of the upper mold. The seal groove is arranged around the gasket molding area. An elastomer seal member is arranged in the seal groove.

[0003] During molding, first, a component is placed on the upper surface (mold surface) of the lower mold in the open state. Next, the upper mold is brought into contact with the component. In other words, the molds are clamped. By clamping the molds, a cavity is defined between the component and the gasket molding portion of the upper mold. Also, by clamping the molds, the seal member in the seal groove of the upper mold comes into elastic contact with the upper surface of the component. The elastic contact of the seal member seals the cavity. Next, the raw material for the gasket is filled into the sealed cavity.

[0004] The sealing member is made of an elastic material. Therefore, even if the component is warped or deformed, the sealing member can adhere to the upper surface of the component when the mold is closed. This prevents the gasket material from leaking out of the cavity when it is filled. This also prevents burrs from occurring.

[0005] JP 2010-040477 A

[0006] However, in the case of the mold in this document, a seal groove and a seal member are required. This makes the configuration of the lower surface (mold surface) of the upper mold complex. In this regard, if a cut-off portion is provided around the gasket molding area, the occurrence of burrs can be suppressed without the need for a seal groove or a seal member. Specifically, instead of a seal groove or a seal member, a cut-off portion protruding downward is provided on the mold surface of the upper mold of the mold in this document. In this way, the cut-off portion presses against the upper surface of the component, thereby sealing the cavity. This prevents the raw material from leaking from the cavity when filling the gasket with raw material. This, in turn, prevents the occurrence of burrs.

[0007] However, depending on the rigidity of the component, the durability of the cut-off portion of the mold may be reduced. That is, in order to reliably seal the cavity, the cut-off portion must be pressed against the upper surface of the component. Therefore, if the component has high rigidity, the cut-off portion becomes more susceptible to damage as the number of shots of the mold increases. That is, the durability of the cut-off portion decreases.

[0008] Therefore, an object of the present disclosure is to provide a mold having a highly durable cut-off portion that can suppress burrs from forming on a gasket, and a composite member for an electrochemical device that can suppress burrs from forming on a gasket.

[0009] (1) In order to solve the above problems, a mold of the present disclosure is a mold for insert molding used to mold a gasket on a thin plate-like substrate placed in a mold, the mold having a cut-off portion that suppresses burrs from the gasket, the mold having an extension direction of a parting line of the mold being an X direction, an opening / closing direction of the mold being a Y direction, a side closer to a cavity for molding the gasket in the X direction being an inner side in the X direction, and a side opposite to the inner side in the X direction being an outer side in the X direction, the mold including: a first mold in which the substrate is placed; and a second mold having the cut-off portion and a cavity recessed portion that is arranged inside the cut-off portion in the X direction and that defines the cavity, wherein the cut-off portion has a planar top surface that protrudes toward the substrate side relative to the parting line and extends in the X direction, a convex inner side surface that is arranged inside the top surface in the X direction, and a convex outer side surface that is arranged outside the top surface in the X direction, and the X-direction width between the convex inner side surface and the convex outer side surface becomes narrower in the direction from the parting line toward the top surface.

[0010] Here, "suppressing burrs" includes, for example, suppressing the generation of burrs themselves and suppressing the extension of generated burrs. According to this configuration, the top surface of the edge cutoff portion is planar and extends in the X direction. Therefore, compared to when the top surface is curved or when the top surface extends in a direction intersecting the X direction, it is possible to suppress the top surface from locally pressing against the substrate (the top surface from contacting the substrate on one side) during mold clamping. Therefore, it is possible to mitigate stress concentration on a portion of the top surface. Therefore, damage to the edge cutoff portion can be suppressed and durability can be improved. Furthermore, the improved durability of the edge cutoff portion allows for greater freedom in selecting the substrate material. For example, a substrate made of a material with a high Young's modulus can be used.

[0011] In addition, the shape accuracy (especially the Y-direction height accuracy) of the cutting edge portion can be improved compared to when no top surface is located on the cutting edge portion (for example, when a pair of side surfaces (convex inner surface, convex outer surface) are directly connected without a top surface).

[0012] The width in the X direction between the pair of side surfaces (the convex inner side surface and the convex outer side surface) narrows in the direction from the parting line toward the top surface, which reduces stress concentration at the boundary between the top surface and the side surfaces during mold clamping, compared to when the width in the X direction between the pair of side surfaces is constant in the direction from the parting line toward the top surface.

[0013] (1-1) In the configuration of (1) above, it is preferable that the first mold is a fixed mold and the second mold is a movable mold when the mold is opened and closed. According to this configuration, the first mold is fixed when the mold is opened and closed (when the mold is opened and closed). A substrate is disposed in the first mold. Therefore, it is possible to suppress displacement of the substrate when the mold is opened and closed.

[0014] (1-2) In any of the above configurations, it is preferable that the cut-off portions are arranged on both sides of the cavity recess in the X direction. With this configuration, burrs can be suppressed on both sides of the cavity recess in the X direction.

[0015] (1-3) In any of the above configurations, it is preferable that the cut-off portion extends in an endless annular shape around the cavity recess when viewed from the Y direction. According to this configuration, the cut-off portion surrounds the cavity recess. Therefore, leakage of the gasket material can be suppressed around the entire cavity recess, i.e., the cavity.

[0016] (1-4) In any of the above configurations, it is preferable that the ratio of the surface area to the plate thickness of the substrate (= surface area / plate thickness) be 30,000 or more and 3,125,000 or less. According to this configuration, the ratio of the surface area to the plate thickness is set to 30,000 or more. Therefore, compared to when the ratio is less than 30,000, the plate thickness becomes larger relative to the surface area, which can prevent the stack (laminate) of an electrochemical device such as a fuel cell from becoming larger. Furthermore, according to this configuration, the ratio of the surface area to the plate thickness is set to 3,125,000 or less. Therefore, compared to when the ratio exceeds 3,125,000, the plate thickness becomes smaller relative to the surface area, which can prevent the separator from becoming prone to excessive deformation.

[0017] According to this configuration, the ratio of the surface area to the thickness of the substrate is set to 30,000 or more and 3,125,000 or less. In other words, the substrate of this configuration is thin plate-like. Therefore, the substrate is moderately prone to deformation. Therefore, when the mold is clamped, the shape precision of the mold is easily reflected (transferred) to the substrate. For example, to improve the durability of the edge cut-off portion, the mold can be hardened to increase its hardness. However, hardening easily causes deformation such as "warping" in the mold. In other words, the shape precision of the mold is likely to decrease. Therefore, when a gasket is molded on a thin plate-like substrate (a substrate that is easily deformed) using this mold, the shape precision of the substrate may decrease.

[0018] In this regard, with this configuration, the durability of the cutting edge can be improved without subjecting the mold to processing for increasing hardness (processing that may reduce the shape accuracy). Therefore, even though the substrate is thin and therefore prone to deformation, it is possible to prevent a reduction in the shape accuracy of the substrate.

[0019] (1-5) In any of the above configurations, it is preferable that the ratio of the surface area of ​​the base material to the Y-direction thickness of the gasket (= surface area / Y-direction thickness) be 5,000 or more and 500,000 or less. According to this configuration, the ratio of the surface area to the Y-direction thickness of the gasket is set to 5,000 or more. Therefore, compared to when the ratio is less than 5,000, the Y-direction thickness of the gasket becomes larger relative to the surface area, which can prevent the stack (laminate) of an electrochemical device such as a fuel cell from becoming larger. Furthermore, according to this configuration, the ratio of the surface area to the Y-direction thickness of the gasket is set to 500,000 or less. Therefore, compared to when the ratio exceeds 500,000, the Y-direction thickness of the gasket becomes smaller relative to the surface area, which can prevent the amount of elastic deformation of the gasket from becoming smaller, thereby preventing a decrease in sealing performance.

[0020] (1-6) In any of the above configurations, it is preferable that the Young's modulus of the material of the second mold be 100%, and the Young's modulus of the material of the substrate be 80% or more and 150% or less. According to this configuration, the Young's modulus is set to 80% or more. Therefore, compared to when the Young's modulus is less than 80%, it is possible to prevent a decrease in the rigidity of the substrate. Furthermore, despite the high rigidity of the substrate, it is possible to ensure the durability of the cutting portion. Furthermore, according to this configuration, the Young's modulus is set to 150% or less. Therefore, compared to when the Young's modulus exceeds 150%, it is possible to prevent the rigidity of the substrate from becoming excessively high.

[0021] (1-7) In the configuration of (1-6) above, it is preferable that the material of the substrate is stainless steel. According to this configuration, the stainless steel oxide film can suppress corrosion of the substrate. Furthermore, compared to when a substrate made of a material with a low Young's modulus (such as titanium) is used, the rigidity of the substrate can be increased. Furthermore, despite the high rigidity of the substrate, the durability of the cutting portion can be improved.

[0022] (1-8) In any of the above configurations, it is preferable that a corner portion be interposed at the boundary between the top surface and the convex inner side surface and at the boundary between the top surface and the convex outer side surface. This configuration can improve the shape accuracy of the cutting edge portion compared to when a rounded chamfered portion (a curved chamfered portion) is interposed at the boundary between the top surface and the convex inner side surface and at the boundary between the top surface and the convex outer side surface.

[0023] (2) In any of the above configurations, it is preferable that the convex inner side surface and the convex outer side surface each have a planar shape. According to this configuration, the pair of side surfaces (the convex inner side surface and the convex outer side surface) both have a planar shape. Therefore, the width in the X direction between the pair of side surfaces gradually narrows in the direction from the parting line toward the top surface. Therefore, it is possible to alleviate stress concentration on a portion of the side surface during mold clamping.

[0024] (3) In any of the above configurations, it is preferable that the intersection angle between the convex inner side surface and the convex outer side surface be an obtuse angle. According to this configuration, the intersection angle between the pair of side surfaces (the convex inner side surface and the convex outer side surface) is set to an obtuse angle (an angle exceeding 90°). Therefore, compared to when the intersection angle is 90° or less, it is possible to alleviate stress concentration at the boundary between the top surface and the side surface during mold clamping.

[0025] (4) In any of the above configurations, it is preferable that the intersection angle be 120° or more and 150° or less. According to this configuration, the intersection angle is set to 120° or more. Therefore, compared to when the intersection angle is less than 120°, it is possible to alleviate stress concentration at the boundary between the top surface and the side surface (convex inner side surface, convex outer side surface) during mold clamping. Also, according to this configuration, the intersection angle is set to 150° or less. Therefore, compared to when the intersection angle exceeds 150°, it is possible to prevent the width of the cutting edge in the X direction from increasing. In other words, it is possible to reduce the size of the cutting edge.

[0026] (4-1) In any of the above configurations, it is preferable that the inclination angle of the convex inner side surface or the convex outer side surface with respect to the Y direction is 60° or more. With this configuration, it is possible to reduce the concentration of stress at the boundary between the top surface and the convex inner side surface or the boundary between the top surface and the convex outer side surface during mold clamping, compared to when the inclination angle is less than 60°.

[0027] (5) In any of the above configurations, it is preferable that the inclination angle of the convex inner surface with respect to the Y direction is the same as the inclination angle of the convex outer surface with respect to the Y direction. With this configuration, it is possible to equalize the stress distribution on both sides in the X direction with respect to the X-direction central axis of the cutting edge portion.

[0028] (6) In any of the above configurations, it is preferable that the convex inner surface extend from the top surface to the inside of the cavity recess, straddling the parting line. With this configuration, stress concentration on the opening edge of the cavity recess during mold clamping can be alleviated compared to when the convex inner surface of the cut-off portion does not straddle the parting line (does not extend to the inside of the cavity recess).

[0029] (7) In any of the above configurations, it is preferable that the second mold be arranged outside the cutting portion in the X direction and have a deformation absorbing recess that absorbs deformation of the base material when the top surface is pressed against the base material.

[0030] When the top surface of the cut-off portion is pressed against the substrate during mold clamping, the substrate may be elastically deformed. Specifically, the substrate may lift off the first mold. In this regard, with this configuration, the deformed portion of the substrate can be accommodated in the deformation-absorbing recess. This allows the apparent cut-off depth (apparent penetration) of the cut-off portion into the substrate to be increased.

[0031] (8) In any of the above configurations, the deformation-absorbing recess has a planar bottom surface that is recessed into the second mold with respect to the parting line and extends in the X direction, a concave inner side surface that is located on the inside of the bottom surface in the X direction, and a concave outer side surface that is located on the outside of the bottom surface in the X direction, and the X-direction width between the concave inner side surface and the concave outer side surface preferably becomes narrower in the direction from the parting line toward the bottom surface.

[0032] According to this configuration, when the deformed portion of the base material has a curved plate shape that bulges in the direction from the parting line toward the bottom surface, the deformed portion can be easily accommodated in the deformation-absorbing recess.

[0033] (9) In any of the above configurations, it is preferable that the cut-off portion and the deformation-absorbing recess are arranged adjacent to each other, and that the convex outer surface and the concave inner surface are smoothly connected from the inside in the X direction toward the outside in the X direction.

[0034] Here, examples of the shape in which the convex outer surface and the concave inner surface are "gently connected" include a shape in which they are connected in a flat plane or a shape in which they are connected in a curved plane. With this configuration, stress concentration at the boundary between the convex outer surface of the cut-off portion and the concave inner surface of the deformation-absorbing recess can be alleviated compared to when the boundary between the convex outer surface of the cut-off portion and the concave inner surface of the deformation-absorbing recess is angular.

[0035] (10) In any of the above configurations, it is preferable that the amount of protrusion of the top surface in the Y direction from the parting line is 10 μm or more and 100 μm or less.

[0036] According to this configuration, the amount of protrusion of the top surface in the Y direction is set to 10 μm or more. Therefore, compared to when the amount of protrusion of the top surface in the Y direction is less than 10 μm, leakage of the gasket material from the cavity can be suppressed. In other words, the sealing performance can be improved. Furthermore, compared to when the amount of protrusion of the top surface in the Y direction is less than 10 μm, the processing accuracy of the mold can be improved.

[0037] Furthermore, with this configuration, the amount of protrusion of the top surface in the Y direction is set to 100 μm or less. Therefore, compared to when the amount of protrusion of the top surface in the Y direction exceeds 100 μm, it is possible to prevent the top surface from excessively cutting into the base material. Therefore, it is possible to prevent damage to the cutting portion and the base material.

[0038] (11) In any of the above configurations, it is preferable that the X-direction width of the top surface is 10 μm or more and 500 μm or less. According to this configuration, the X-direction width of the top surface is set to 10 μm or more. Therefore, compared to when the X-direction width of the top surface is less than 10 μm, leakage of the gasket material from the cavity can be suppressed. In other words, the sealing performance can be improved.

[0039] Furthermore, with this configuration, the width of the top surface in the X direction is set to 500 μm or less. Therefore, the area of ​​the top surface that is pressed against the substrate can be made smaller than when the width of the top surface in the X direction exceeds 500 μm. Therefore, damage to the cutting portion and the substrate can be suppressed.

[0040] (12) In any of the above configurations, it is preferable that the cut-off portion is arranged at a predetermined distance outward in the X direction from the cavity recess. According to this configuration, the cut-off portion is arranged offset outward in the X direction from the cavity recess. Therefore, compared to when the cut-off portion is arranged adjacent to the cavity recess, it is possible to alleviate stress concentration at the boundary between the cut-off portion and the cavity recess during mold clamping.

[0041] (13) To achieve the above object, the present disclosure provides a composite member for an electrochemical device comprising a substrate and a gasket disposed on a surface of the substrate, wherein the extending direction of the surface is an X-direction, the stacking direction of the substrate and the gasket is a Y-direction, the side closer to the gasket in the X-direction is the inner side in the X-direction, and the side opposite the inner side in the X-direction is the outer side in the X-direction, the substrate has, on its surface, a concave trace portion and a gasket disposing portion disposed inside the trace portion in the X-direction and on which the gasket is disposed, the trace portion has a planar bottom surface, a trace portion concave inner side surface disposed inside the bottom surface in the X-direction, and a trace portion concave outer side surface disposed outside the bottom surface in the X-direction, and the X-direction width between the trace portion concave inner side surface and the trace portion concave outer side surface narrows in a direction from the surface toward the bottom surface. Here, examples of the "electrochemical device" include a fuel cell and a water electrolysis device.

[0042] According to this configuration, the width in the X direction between the pair of side surfaces (the inner surface of the concave trace portion and the outer surface of the concave trace portion) narrows in the direction from the surface to the bottom surface, which reduces the concentration of residual stress at the boundary between the bottom surface and the side surfaces compared to when the width in the X direction between the pair of side surfaces is constant in the direction from the surface to the bottom surface.

[0043] Furthermore, according to this configuration, when a composite member for an electrochemical device is manufactured using a mold having any of the above configurations, burrs from the gasket can be suppressed. As a result, the shape accuracy of the gasket can be improved. Note that "burr suppression" includes, for example, a configuration in which the generation of burrs themselves is suppressed and a configuration in which the extension of generated burrs is suppressed.

[0044] When a composite member for an electrochemical device is manufactured using a mold having any of the above configurations, the bottom surface of the trace portion is formed by the top surface of the cut-off portion, the concave inner surface of the trace portion is formed by the convex inner surface of the cut-off portion, and the concave outer surface of the trace portion is formed by the convex outer surface of the cut-off portion.

[0045] The top surface of the cut-off portion is planar and extends in the X direction. Therefore, compared to when the top surface is curved or when the top surface extends in a direction intersecting the X direction, it is possible to prevent the top surface from being locally pressed against the substrate (the top surface from contacting one side of the substrate) during mold clamping. This reduces stress concentration on a portion of the top surface, i.e., residual stress concentration on a portion of the bottom surface of the trace portion. Furthermore, compared to when no top surface is provided on the cut-off portion, it is possible to improve the shape accuracy of the cut-off portion, i.e., the trace portion.

[0046] The X-direction width between the pair of side surfaces (convex inner surface, convex outer surface) of the cutoff portion narrows in the direction from the parting line toward the top surface. Therefore, compared to when the X-direction width between the pair of side surfaces is constant in the direction from the parting line toward the top surface, it is possible to alleviate stress concentration at the boundary between the top surface and the side surfaces during mold clamping. Therefore, it is possible to suppress residual stress concentration at the boundary between the bottom surface of the trace portion and the side surfaces (concave inner surface of the trace portion, concave outer surface of the trace portion).

[0047] The mold of the present disclosure can increase the durability of the cutting edge portion. Furthermore, burrs from the gasket can be suppressed. The composite member for an electrochemical device of the present disclosure can suppress burrs from the gasket.

[0048] FIG. 1 is a top view of a composite member for a fuel cell according to a first embodiment. FIG. 2 is an enlarged view of the area enclosed by frame II in FIG. 1. FIG. 3 is a cross-sectional view taken along the line III-III in FIG. 2. FIG. 4 is an enlarged view of the area enclosed by frame IV in FIG. 3. FIG. 5 is a cross-sectional view of a mold used in manufacturing the composite member for a fuel cell. FIG. 6 is a partial cross-sectional view of a mold in an injection step (shaping step (mold open state)) of the manufacturing method for the composite member for a fuel cell. FIG. 7 is a partial cross-sectional view of a mold in an injection step (shaping step (mold clamped state)) of the manufacturing method. FIG. 8 is an enlarged view of the area enclosed by frame VIII in FIG. 7. FIG. 9 is a partial cross-sectional view of a mold in an injection step (injection step) of the manufacturing method. FIG. 10 is an enlarged view of the area enclosed by frame X in FIG. 9. FIG. 11 is a partial cross-sectional view of a mold in a vulcanization step of the manufacturing method. FIG. 12 is an enlarged view of the area enclosed by frame XII in FIG. 11. FIG. 13 is a partial cross-sectional view of a mold according to a second embodiment. FIG. 14 is a partial cross-sectional view of a mold according to a third embodiment. Fig. 15 is a partial cross-sectional view of a mold according to a fourth embodiment Fig. 16 is a partial top view of a composite member for a fuel cell according to another embodiment.

[0049] Hereinafter, embodiments of the mold and the composite member for a fuel cell according to the present disclosure will be described. The composite member for a fuel cell is included in the concept of the "composite member for an electrochemical device" according to the present disclosure.

[0050] First Embodiment [Configuration of Composite Member for Fuel Cell] First, the configuration of a composite member for a fuel cell of this embodiment will be described. In the following figures, at least one of the front-rear and left-right directions (horizontal directions) corresponds to the "X direction" in this disclosure. The up-down direction (vertical direction) corresponds to the "Y direction" in this disclosure.

[0051] Fig. 1 shows a top view (surface view) of a composite member for a fuel cell according to this embodiment. Fig. 2 shows an enlarged view of the area within frame II in Fig. 1. Fig. 3 shows a cross-sectional view taken along the line III-III in Fig. 2. Fig. 4 shows an enlarged view of the area within frame IV in Fig. 3.

[0052] For ease of explanation, the gasket 4 is hatched in Fig. 1. The burr B is omitted. The trace 21 is shown schematically by a straight line. In Fig. 2, the gasket 4 is sparsely hatched, and the burr B is densely hatched. In Figs. 3 and 4, the burr B is shown by a thick line.

[0053] As shown in FIG. 1 , the composite member 1 for a fuel cell is a gasket-integrated separator. A membrane electrode assembly (MEA) (hereinafter referred to as the "power generation section"), in which gas diffusion layers (GDLs) (not shown) are stacked, is stacked within a frame H on the upper surface (surface) 2U. A fuel cell stack is formed by alternately stacking a plurality of composite members 1 for a fuel cell and a plurality of power generation sections in the vertical direction (front-to-back direction, stacking direction). The composite member 1 for a fuel cell includes a separator 2 and a plurality of gaskets 4. The separator 2 is included in the concept of "substrate" in this disclosure.

[0054] 2 and 3 , the left side portion (frame inner portion) and the right side portion (frame outer portion) are identical in configuration with respect to the central axis of the gasket placement portion 20 (gasket 4) in the frame inner / outer direction (direction perpendicular to the extension direction of the gasket placement portion 20), i.e., the X-direction central axis A. The arrangements of the left side portion and the right side portion are symmetrical in the left-right direction (frame inner / outer direction) with respect to the X-direction central axis A. Below, the configuration and arrangement of the right side portion will be mainly described as a representative of the configuration and arrangement on both the left and right sides.

[0055] (Separator 2) As shown in Figures 1 to 3, the separator 2 is made of stainless steel (corrosion-resistant steel) and has a rectangular thin plate shape. The separator 2 has a plurality of manifolds (openings) 23 for gas and air. A plurality of gasket placement portions 20 and a plurality of trace portions 21 are arranged on the upper surface 2U of the separator 2. The upper surface 2U of the separator 2 is included in the concept of "surface of the substrate" in this disclosure.

[0056] As shown in Fig. 1, the gasket placement portion 20 has a frame shape. As shown in Fig. 3, the gasket placement portion 20 has a planar shape. The gasket 4 is placed in the gasket placement portion 20.

[0057] A pair of traces 21 are arranged on the inner and outer sides of the frame of any gasket placement portion 20 shown in FIG. 1 (i.e., both sides in the X direction). The traces 21 are frame-shaped. As shown in FIG. 2, the traces 21 extend along the gasket placement portion 20. The traces 21 and the gasket placement portion 20 are arranged at a predetermined distance in the frame inward / outward direction (X direction). As shown in FIGS. 3 and 4, the traces 21 are recessed in the upper surface 2U of the separator 2.

[0058] As shown in Figures 2 to 4, of the pair of left and right trace portions 21, the right trace portion 21 has a bottom surface 210, a trace portion concave inner surface 211, and a trace portion concave outer surface 212. The bottom surface 210 is located at a position that protrudes downward (toward the interior of the separator 2) relative to the upper surface 2U. The bottom surface 210 has a planar shape extending in the front-to-rear and left-to-right direction (X direction). The trace portion concave inner surface 211 is located on the left side of the bottom surface 210 (inside in the X direction, toward the gasket placement portion 20). The trace portion concave inner surface 211 has a planar shape. The trace portion concave inner surface 211 connects the upper surface 2U and the bottom surface 210. The trace portion concave outer surface 212 is located on the right side of the bottom surface 210 (outside in the X direction, opposite the gasket placement portion 20). The trace portion concave outer surface 212 has a planar shape. The concave outer surface 212 of the trace portion connects the top surface 2U and the bottom surface 210.

[0059] As shown in FIG. 4 , the X-direction width (left-right direction width) W1 between the trace portion concave inner surface 211 and the trace portion concave outer surface 212 gradually decreases from the top to the bottom (from the top surface 2U to the bottom surface 210). That is, the trace portion concave inner surface 211 and the trace portion concave outer surface 212 are arranged in a tapered shape that narrows from the top to the bottom. The intersection angle θ1 between the trace portion concave inner surface 211 and the trace portion concave outer surface 212 is an obtuse angle. The intersection angle θ1 is in the range of 120° to 150°. The inclination angle α1 of the trace portion concave inner surface 211 with respect to the up-down direction (Y direction) and the inclination angle β1 of the trace portion concave outer surface 212 with respect to the up-down direction (Y direction) are the same.

[0060] (Gaskets 4) As shown in Fig. 3, the gaskets 4 are fixed and laminated on the upper surface 2U of the separator 2. As shown in Fig. 1, the gaskets 4 are made of rubber (thermosetting elastomer) and have a frame shape. The large central gasket 4 surrounds the two left and right manifolds 23 and the frame H (power generation section) from the outside in the planar direction in an endless annular shape. Each of the remaining gaskets 4 surrounds a manifold 23 from the outside in the planar direction in an endless annular shape.

[0061] As shown in Figures 1 to 4, the gasket 4 is disposed in the gasket disposing portion 20. As shown in Figure 2, a pair of burrs B is formed on the inner and outer sides of the frame of any gasket 4 shown in Figure 1. As shown in Figure 2, the burrs B extend along the gasket 4. As shown in Figures 2 to 4, of the pair of left and right burrs B, the right burr B extends to the right side of the gasket 4 (in the direction away from the gasket 4). However, as will be described later, the presence or absence, shape, size, number, etc. of the burrs B are not particularly limited.

[0062] [Configuration of Mold] Next, the configuration of a mold used in manufacturing the composite material for a fuel cell of this embodiment will be described. As will be described later, the manufacturing method of the composite material for a fuel cell of this embodiment includes an injection step and a vulcanization step (crosslinking step).

[0063] Figure 5 shows a cross-sectional view of a mold used to manufacture the composite member for a fuel cell of this embodiment. Note that the left-right intermediate portion is omitted. The cross section of the separator 2 shown in Figure 5 corresponds to the VV cross section in Figure 1. Box II in Figure 5 corresponds to box II in Figure 1.

[0064] FIG. 6 shows a partial cross-sectional view of a mold in the injection step (shaping step (mold open state)) of the manufacturing method of a composite member for a fuel cell of this embodiment. FIG. 7 shows a partial cross-sectional view of a mold in the injection step (shaping step (mold closed state)) of the same manufacturing method. FIG. 8 shows an enlarged view of the area enclosed by frame VIII in FIG. 7. FIG. 9 shows a partial cross-sectional view of a mold in the injection step (injection step) of the same manufacturing method. FIG. 10 shows an enlarged view of the area enclosed by frame X in FIG. 9. FIG. 11 shows a partial cross-sectional view of a mold in the vulcanization step of the same manufacturing method. FIG. 12 shows an enlarged view of the area enclosed by frame XII in FIG. 11. Note that FIGS. 6, 7, 9, and 11 correspond to FIG. 3 (the cross-sectional view taken along the line III-III in FIG. 2). FIGS. 8, 10, and 12 correspond to frame IV in FIG. 4.

[0065] 6, 7, 9, and 11, the left side (frame inner side) and the right side (frame outer side) of the gasket mounting portion 20 (gasket 4) are identical in configuration with respect to the X-direction central axis A in the frame inner / outer direction (see FIG. 1). The arrangements of the left side and right side are symmetrical in the left-right direction (frame inner / outer direction) with respect to the X-direction central axis A. Below, the configuration and arrangement of the right side will be mainly described, representing the configuration and arrangement on both the left and right sides.

[0066] As shown in FIG. 5 , the mold (forming mold) 5 includes a first mold 5D and a second mold 5U. The first mold 5D and the second mold 5U are made of iron. The mold 5 is used to form a gasket 4 on a thin separator 2 placed inside the mold. The mold 5 includes a cut-off portion 50 that suppresses flash B from the gasket 4. The parting line PL of the mold 5 extends horizontally (X direction). The opening and closing direction of the mold 5 (mold opening-mold clamping direction) corresponds to the up-down direction (Y direction). Guide members (not shown) are arranged on the outer lateral sides (horizontal outer sides) of the mold 5. The guide members position the mold 5 horizontally.

[0067] (First mold 5D) As shown in Fig. 5 , a plurality of manifold protrusions 53 protrude upward (toward the second mold 5U) from a mold surface 50D of the first mold 5D. In the injection process described below, the separator 2 is placed on the mold surface 50D. The manifold 23 of the separator 2 is inserted into the manifold protrusions 53.

[0068] (Second mold 5U) As shown in Fig. 5, the second mold 5U is disposed above the first mold 5D, facing it in the vertical direction. The second mold 5U can move toward and away from the first mold 5D from above. In the injection process described below, the first mold 5D is a fixed mold, and the second mold 5U is a movable mold.

[0069] 7 and 8, the vertical position of the mold surface (molding surface) 50U of the second mold 5U corresponds to the parting line PL. The mold surface 50U is provided with a cavity recess 51, a pair of left and right edge cut-off portions 50, and a pair of left and right deformation-absorbing recesses 52.

[0070] 8, the cavity recess 51 is recessed upward from the mold surface 50U (toward the interior of the second mold 5U). In the injection process described below, the cavity recess 51, together with the gasket placement portion 20 of the separator 2, defines a cavity 5M for molding the gasket 4.

[0071] As shown in FIG. 7 , of the pair of left and right edge cutoff portions 50, the right edge cutoff portion 50 is positioned a predetermined distance to the right (toward the deformation-absorbing recess 52, outward in the X direction) from the cavity recess 51. As shown in FIG. 8 , the edge cutoff portion 50 protrudes downward (toward the separator 2) from the mold surface 50U. The vertical cross section of the edge cutoff portion 50 is trapezoidal, tapering from top to bottom. During the injection process described below, the edge cutoff portion 50 prevents the raw material G (see FIG. 10 ) from leaking from the cavity 5M. In other words, it prevents flash B (see FIG. 12 ).

[0072] As shown in FIG. 8 , the edge cutoff portion 50 has a top surface 500, a convex inner surface 501, and a convex outer surface 502. The top surface 500 is positioned at a position that protrudes downward from the parting line PL (mold surface 50U). The top surface 500 has a planar shape extending horizontally (X direction). The convex inner surface 501 is positioned on the left side of the top surface 500 (the cavity recess 51 side, inside in the X direction). The convex inner surface 501 has a planar shape. The convex inner surface 501 connects the parting line PL (mold surface 50U) and the top surface 500. The convex outer surface 502 is positioned on the right side of the top surface 500 (the side opposite the cavity recess 51 side, the deformation absorbing recess 52 side, outside in the X direction). The convex outer surface 502 has a planar shape. The convex outer surface 502 connects the parting line PL (mold surface 50U) and the top surface 500.

[0073] As shown in FIG. 8 , the X-direction width (left-right direction width) W2 between the convex inner surface 501 and the convex outer surface 502 gradually decreases from the top to the bottom (from the parting line PL toward the top surface 500). That is, the convex inner surface 501 and the convex outer surface 502 are arranged in a tapered shape that narrows from the top to the bottom. The intersection angle θ2 between the convex inner surface 501 and the convex outer surface 502 is an obtuse angle. The intersection angle θ2 is in the range of 120° to 150°. The inclination angle α2 of the convex inner surface 501 relative to the vertical direction and the inclination angle β2 of the convex outer surface 502 relative to the vertical direction are the same.

[0074] The trace 21 of the separator 2 described above is formed by the cutting edge portion 50 being pressed against the upper surface 2U of the separator 2. Therefore, the cutting edge portion 50 and the trace 21 have shape symmetry. Therefore, as shown in FIG. 8 , the intersection angle θ1 of the trace 21 and the intersection angle θ2 of the cutting edge portion 50 are approximately the same. Furthermore, the inclination angle α1 of the trace 21 and the inclination angle α2 of the cutting edge portion 50 are approximately the same. Furthermore, the inclination angle β1 of the trace 21 and the inclination angle β2 of the cutting edge portion 50 are approximately the same.

[0075] As shown in Fig. 7, of the pair of left and right deformation absorbing recesses 52, the right deformation absorbing recess 52 is located immediately to the right of the right edge cut-off portion 50. In other words, the edge cut-off portion 50 and the deformation absorbing recess 52 are located adjacent to each other. As shown in Fig. 8, the deformation absorbing recess 52 is recessed upward from the mold surface 50U. The vertical cross section of the deformation absorbing recess 52 has a trapezoidal shape that tapers from bottom to top.

[0076] As shown in FIG. 8 , the deformation-absorbing recess 52 includes a bottom surface 520, a recessed inner surface 521, and a recessed outer surface 522. The bottom surface 520 is positioned above the parting line PL (mold surface 50U). The bottom surface 520 has a planar shape extending horizontally. The recessed inner surface 521 is positioned on the left side of the bottom surface 520 (the cavity recess 51 side; inward in the X direction). The recessed inner surface 521 has a planar shape. As shown in FIG. 8 , the recessed inner surface 521 and the convex outer surface 502 of the edge-cutting portion 50 are connected in a planar shape without bending. That is, the recessed inner surface 521 and the convex outer surface 502 are connected smoothly. The recessed outer surface 522 is positioned on the right side of the bottom surface 520 (the opposite side of the cavity recess 51 side; outward in the X direction). The recessed outer surface 522 has a planar shape.

[0077] 8, the width in the left-right direction between the recessed inner surface 521 and the recessed outer surface 522 gradually decreases from the bottom side to the top side (from the parting line PL to the bottom surface 520). In other words, the recessed inner surface 521 and the recessed outer surface 522 are arranged in a tapered shape that narrows from the bottom side to the top side.

[0078] [Method for manufacturing composite material for fuel cell] Next, a method for manufacturing the composite material for fuel cell of this embodiment will be described. As described above, the manufacturing method of this embodiment includes the injection step and the vulcanization step (crosslinking step).

[0079] (Injection Process) The injection process includes a separator placement process, a shaping process, and a pouring process. As shown in Figure 5, in the separator placement process, the separator 2 is placed from above on the mold surface 50D of the first mold 5D of the mold 5 in the open state. Note that an adhesive (not shown) has been applied to the upper surface 2U of the separator 2 in advance. When placing the separator 2, the manifold projection 53 is inserted into the manifold 23 of the separator 2. In other words, the separator 2 is positioned on the mold surface 50D.

[0080] As shown in Figures 6 to 8, in the shaping process, the second mold 5U is pressed against the first mold 5D with a predetermined mold clamping force. That is, the mold is clamped. By clamping the mold, the cut-off portion 50 is pressed against the upper surface 2U of the separator 2. At this time, the top surface 500 of the cut-off portion 50 is pressed against the upper surface 2U entirely without being in partial contact with the upper surface 2U. This pressing causes a recessed trace portion 21 to be formed in the upper surface 2U.

[0081] As shown in an exaggerated manner in Figure 8, when the cut-off portion 50 recesses the trace portion 21 in the separator 2, the portion 22 of the separator 2 adjacent to the trace portion 21 rises above the mold surface 50D. Here, the deformation-absorbing recess 52 of the second mold 5U is positioned to correspond to the adjacent portion 22. Therefore, the raised adjacent portion 22 is accommodated in the deformation-absorbing recess 52. In this way, the deformation-absorbing recess 52 absorbs deformation of the separator 2 when the top surface 500 of the cut-off portion 50 is pressed against the separator 2.

[0082] As the number of shots of the mold 5 increases, the mold surface 50D may be recessed by the cut-off portion 50. In this case, as shown by dotted lines in Figures 7 and 8, a convex portion 24 is formed on the lower surface 2D. Also, a concave portion 54 is formed on the mold surface 50D. When viewed from the top-bottom direction (in a plan view), the cut-off portion 50, the trace portion 21, the convex portion 24, and the concave portion 54 overlap.

[0083] 9 and 10 , in the injection process, the raw material G of the gasket 4 is injected and filled into the cavity 5M after the mold is closed. Due to the injection pressure, the raw material G attempts to leak out of the cavity 5M through the boundary between the mold surface 50U of the second mold 5U and the upper surface 2U of the separator 2. However, the cut-off portion 50 of the mold surface 50U is pressed against the trace portion 21 on the upper surface 2U. Therefore, the raw material G is unlikely to leak out of the cavity 5M.

[0084] (Vulcanization Process) In the vulcanization process, first, the mold 5 in the state after the injection process (mold-clamped state) is transported from the location where the injection process is performed to the location where the vulcanization process is performed. Next, as shown in FIGS. 11 and 12 , the mold 5 in the mold-clamped state is heated at a predetermined temperature for a predetermined time to harden the raw material G in the cavity 5M and produce the gasket 4. The gasket 4 is then adhered and fixed to the gasket placement portion 20 using an adhesive applied to the upper surface 2U of the separator 2. The mold is then opened, and the fuel cell composite member 1 is removed from the mold 5. Note that the deformation of the adjacent portion 22 in the previous process (injection process) (from a flat plate shape to a curved plate shape as shown in FIGS. 6 to 8 ) is elastic deformation. Therefore, upon mold opening, the adjacent portion 22 returns to its shape before mold clamping (see FIG. 6 ). That is, the adjacent portion 22 returns from a curved plate shape to a flat plate shape.

[0085] In the previous process (injection process), the cut-off portion 50 is pressed against the trace portion 21. This makes it difficult for the raw material G to leak out of the cavity 5M. Therefore, after this process (vulcanization process), burrs B are unlikely to form in the composite material 1 for a fuel cell. In addition, the burrs B are unlikely to stretch.

[0086] [Effects] Next, the effects of the mold and fuel cell composite member of this embodiment will be described. As shown in FIG. 8 , the top surface 500 of the separator 50 is planar and extends horizontally (the extension direction of the parting line PL, a direction perpendicular to the up-down direction (the opening and closing direction of the mold 5)). Therefore, compared to when the top surface 500 is curved or when the top surface 500 extends in a direction intersecting the horizontal direction, the top surface 500 is prevented from locally pressing against the separator 2 (i.e., the top surface 500 is prevented from contacting one side of the separator 2) during mold clamping. This reduces stress concentration on a portion of the top surface 500. This reduces damage to the separator 50 and improves its durability. Furthermore, the improved durability of the separator 50 allows for greater freedom in selecting materials for the separator 2. For example, the separator 2 can be made of a material with a high Young's modulus (such as stainless steel).

[0087] Furthermore, compared to when the cutting edge portion 50 does not have a top surface 500 (for example, when a pair of side surfaces (convex inner surface 501 and convex outer surface 502) shown in Figure 8 are directly connected without being connected via the top surface 500), the shape accuracy of the cutting edge portion 50 (especially the vertical height accuracy) can be improved.

[0088] 8 , the width in the left-right direction between the pair of side surfaces (convex inner surface 501, convex outer surface 502) narrows from top to bottom (from parting line PL to top surface 500). Therefore, compared to when the width in the left-right direction between the pair of side surfaces is constant from top to bottom, in other words, compared to when the pair of side surfaces extend in the vertical direction, it is possible to alleviate the concentration of stress at the boundary between top surface 500 and the side surfaces (i.e., corner C2) during mold clamping.

[0089] As shown in Figure 5, the first mold 5D is a fixed mold, and the second mold 5U is a movable mold. That is, when the mold 5 is opened and closed in the injection process, the first mold 5D is fixed. A separator 2 is disposed in the first mold 5D. Therefore, it is possible to prevent the separator 2 from shifting position when the mold 5 is opened and closed.

[0090] As shown in Fig. 6, the cut-off portions 50 are disposed on both the left and right sides of the cavity recess 51. This makes it possible to suppress the generation of burrs B shown in Figs. 11 and 12 on both the left and right sides (inside and outside the frame) of the cavity recess 51. It also makes it possible to suppress the extension of the burrs B.

[0091] As shown in Fig. 1 , when viewed from the top-bottom direction (in a plan view), the trace portion 21 extends in an endless annular shape around the gasket 4. As shown in Fig. 11 , the trace portion 21 corresponds to the cut-off portion 50. The gasket 4 corresponds to the cavity recess 51. Therefore, when viewed from the top-bottom direction, the cut-off portion 50 extends in an endless annular shape around the cavity recess 51. In other words, the cut-off portion 50 surrounds the cavity recess 51. Therefore, as shown in Fig. 9 , leakage of the raw material G of the gasket 4 can be suppressed around the entire circumference of the cavity recess 51, i.e., the cavity 5M.

[0092] The ratio (=surface area / plate thickness) of the surface area (area of ​​the upper surface 2U) of the separator 2 shown in FIG. 1 to the plate thickness (vertical thickness) of the separator 2 shown in FIG. 3 is within the range of 30,000 or more and 3,125,000 or less. That is, the separator 2 has a thin plate shape. Therefore, compared to when the ratio is less than 30,000, the plate thickness becomes larger relative to the surface area, which prevents the fuel cell stack (laminate) from becoming larger. Furthermore, compared to when the ratio exceeds 3,125,000, the plate thickness becomes smaller relative to the surface area, which prevents the separator 2 from becoming prone to excessive deformation. The above ratio is expressed in terms of distance L. The unit of surface area is mm ２ , the unit of plate thickness is mm, and the unit of ratio is mm.

[0093] A separator 2 having the above ratio (surface area / plate thickness) in the range of 30,000 to 3,125,000 exhibits a thin plate shape and is moderately easy to deform. Therefore, as shown in Figures 7 and 8, the shape precision of the mold surface 50U of the second mold 5U is easily reflected (transferred) to the upper surface 2U of the separator 2 during mold clamping. For example, to improve the durability of the edge cutoff portion 50, the second mold 5U including the edge cutoff portion 50 may be hardened to increase its hardness. However, hardening easily causes deformation such as "warping" in the second mold 5U. In other words, the shape precision of the second mold 5U is likely to decrease. Therefore, if a gasket 4 is molded on a thin separator 2 (a separator 2 that is easily deformed) using a hardened second mold 5U, the shape precision of the separator 2 may decrease.

[0094] In this regard, the mold 5 of this embodiment can improve the durability of the cut-off portion 50 without having to perform any processing to increase the hardness (processing that may reduce the shape accuracy) on the mold 5. Therefore, even though the separator 2 has a thin plate shape, that is, even though the separator 2 is easily deformed, it is possible to prevent a reduction in the shape accuracy of the separator 2.

[0095] The ratio (= surface area / vertical thickness) of the surface area of ​​the separator 2 in Fig. 1 to the vertical thickness of the gasket 4 shown in Fig. 3 is in the range of 5,000 to 500,000. Therefore, compared to when this ratio is less than 5,000, the vertical thickness of the gasket 4 becomes larger relative to the surface area, which prevents the fuel cell stack (laminate) from becoming larger. Also, compared to when this ratio exceeds 500,000, the vertical thickness of the gasket 4 becomes smaller relative to the surface area, which prevents the amount of elastic deformation of the gasket 4 from becoming smaller, and therefore prevents a decrease in sealing performance. The above ratio is expressed in terms of distance L. The unit of surface area is mm ２ The unit of the thickness in the vertical direction is mm, and the unit of the ratio is mm.

[0096] The Young's modulus of the material of the second mold 5U is set to 100%, and the Young's modulus of the material of the separator 2 is within the range of 80% to 150%. Therefore, compared to when the Young's modulus of the material of the separator 2 is less than 80%, a decrease in the rigidity of the separator 2 can be suppressed. Furthermore, despite the high rigidity of the separator 2, the durability of the cut-off portion 50 can be ensured. Furthermore, compared to when the Young's modulus of the material of the separator 2 exceeds 150%, an excessive increase in the rigidity of the separator 2 can be suppressed.

[0097] The separator 2 is made of stainless steel. Therefore, the oxide film of the stainless steel can suppress corrosion of the separator 2. Furthermore, the rigidity of the separator 2 can be increased compared to when a separator 2 made of a material with a low Young's modulus (such as titanium) is used. Furthermore, despite the high rigidity of the separator 2, the durability of the cut-off portion 50 can be improved.

[0098] 8 , corners C2 are present at the boundary between top surface 500 and convex inner side surface 501 and at the boundary between top surface 500 and convex outer side surface 502. Therefore, the shape precision of cut-off portion 50 can be improved compared to when rounded chamfered portions (curved chamfered portions) are present at the boundary between top surface 500 and convex inner side surface 501 and at the boundary between top surface 500 and convex outer side surface 502.

[0099] 8, the convex inner side surface 501 and the convex outer side surface 502 each have a flat shape. Therefore, the width in the left-right direction between the pair of side surfaces (the convex inner side surface 501 and the convex outer side surface 502) gradually narrows in the direction from the parting line PL toward the top surface 500. Therefore, it is possible to alleviate the concentration of stress on a part of the side surface during mold clamping.

[0100] 8, the intersection angle θ2 between the convex inner surface 501 and the convex outer surface 502 is an obtuse angle. Therefore, compared to when the intersection angle θ2 is 90° or less, it is possible to reduce the concentration of stress at the boundary between the top surface 500 and the side surfaces (the convex inner surface 501 and the convex outer surface 502), i.e., at the corner C2, during mold clamping.

[0101] As shown in Fig. 8, the intersection angle θ2 is in the range of 120° to 150°. Therefore, compared to when the intersection angle θ2 is less than 120°, it is possible to alleviate stress concentration at the corner C2 during mold clamping. Furthermore, compared to when the intersection angle θ2 is more than 150°, it is possible to prevent the width of the cut-off portion 50 in the left-right direction from increasing. In other words, it is possible to reduce the size of the cut-off portion 50.

[0102] 8, the inclination angle α2 of the convex inner side surface 501 with respect to the vertical direction and the inclination angle β2 of the convex outer side surface 502 with respect to the vertical direction are each 60° or more. Therefore, compared to when the inclination angles α2 and β2 are less than 60°, it is possible to alleviate the concentration of stress at the corner C2 during mold clamping.

[0103] As shown in Fig. 8, the inclination angle α2 and the inclination angle β2 are the same, which makes it possible to equalize the stress distribution on both sides in the left-right direction (inside and outside the frame) with respect to the central axis of the cut-off portion 50 in the X direction (more specifically, the axis that passes through the center of the cut-off portion 50 in the left-right direction, extends in the up-down direction, and is parallel to the central axis A in the X direction in Fig. 7).

[0104] As shown in FIG. 8 , the second mold 5U includes a deformation-absorbing recess 52. The deformation-absorbing recess 52 is located to the right (outside in the X direction) of the cut-off portion 50. The deformation-absorbing recess 52 can absorb deformation of the separator 2 when the top surface 500 is pressed against the separator 2. That is, when the top surface 500 of the cut-off portion 50 is pressed against the upper surface 2U of the separator 2 during mold clamping, the separator 2 may be elastically deformed. Specifically, the separator 2 may lift off the mold surface 50D of the first mold 5D. In this regard, the fuel cell composite member 1 of this embodiment can accommodate the deformed portion of the separator 2 (the adjacent portion 22) in the deformation-absorbing recess 52. This allows for an increased apparent cut-off depth (apparent penetration amount) D of the cut-off portion 50 relative to the separator 2.

[0105] 8 , the width in the left-right direction (width in the X direction) between the recessed inner surface 521 and the recessed outer surface 522 of the deformation absorbing recess 52 narrows from the bottom to the top (from the parting line PL to the bottom surface 520). Therefore, when the adjacent portion 22 elastically deforms from a flat plate shape to a curved plate shape (a curved plate shape that bulges from the bottom to the top), the adjacent portion 22 can be easily accommodated in the deformation absorbing recess 52.

[0106] 8, the cut-off portion 50 and the deformation-absorbing recess 52 are disposed adjacent to each other in the left-right direction. From the left side (inner side in the X direction) to the right side (outer side in the X direction), the convex outer surface 502 of the cut-off portion 50 and the concave inner surface 521 of the deformation-absorbing recess 52 are smoothly connected in a flat shape. Therefore, compared to when the boundary between the convex outer surface 502 and the concave inner surface 521 is angular, it is possible to alleviate stress concentration at the boundary.

[0107] As shown in FIG. 10 , the Y-direction protrusion amount (vertical protrusion amount) E of the top surface 500 relative to the parting line PL is set to 20 μm. That is, the Y-direction protrusion amount E is in the range of 10 μm to 100 μm. Therefore, compared to when the Y-direction protrusion amount E is less than 10 μm, the raw material G of the gasket 4 is prevented from passing through the boundary between the cut-off portion 50 and the trace portion 21. This prevents the raw material G from leaking from the cavity 5M to the outside. That is, the sealing performance is improved. Furthermore, compared to when the Y-direction protrusion amount E is less than 10 μm, the processing accuracy of the mold 5 is improved. Furthermore, compared to when the Y-direction protrusion amount E is more than 100 μm, the top surface 500 is prevented from excessively cutting into the separator 2. This prevents damage to the cut-off portion 50 and the separator 2.

[0108] As shown in FIG. 10 , the X-direction width (left-right width) F of the top surface 500 is set to 70 μm. That is, the X-direction width F is in the range of 10 μm to 500 μm. Therefore, compared to when the X-direction width F is less than 10 μm, the raw material G of the gasket 4 is prevented from passing through the boundary between the cut-off portion 50 and the trace portion 21. This prevents the raw material G from leaking from the cavity 5M to the outside. In other words, the sealing performance is improved. Furthermore, compared to when the X-direction width F exceeds 500 μm, the pressure contact area of ​​the top surface 500 against the separator 2 is reduced. This prevents damage to the cut-off portion 50 and the separator 2.

[0109] 8, the cut-off portion 50 is disposed at a predetermined distance to the right (outside in the X direction) from the cavity recess 51. That is, the cut-off portion 50 is disposed offset to the right from the cavity recess 51. Therefore, compared to when the cut-off portion 50 is disposed adjacent to the cavity recess 51, it is possible to alleviate stress concentration at the boundary between the cut-off portion 50 and the cavity recess 51 during mold clamping.

[0110] 4, the left-right width between the pair of side surfaces (the trace portion concave inner surface 211 and the trace portion concave outer surface 212) of the trace portion 21 of the composite member 1 for a fuel cell narrows from the top to the bottom (from the top surface 2U to the bottom surface 210). Therefore, compared to when the left-right width between the pair of side surfaces is constant from the top to the bottom, it is possible to reduce the concentration of residual stress at the boundary between the bottom surface 210 and the side surfaces (the trace portion concave inner surface 211 and the trace portion concave outer surface 212), i.e., at the corner C1.

[0111] Furthermore, the composite member 1 for a fuel cell of this embodiment is manufactured using the mold 5 of this embodiment (as shown in FIG. 9, a mold 5 having a pair of cut-off portions 50 on both left and right sides (inside and outside the frame) of the cavity recess 51). Therefore, as shown in FIG. 2, the generation of burrs B can be suppressed on both left and right sides (inside and outside the frame) of the gasket 4. Also, the extension of burrs B can be suppressed. Also, the area occupied by burrs B on the upper surface 2U can be reduced.

[0112] As shown in Figure 12, the bottom surface 210 of the trace portion 21 is formed by the top surface 500 of the cut-off portion 50, the concave inner surface 211 of the trace portion of the trace portion 21 is formed by the convex inner surface 501 of the cut-off portion 50, the concave outer surface 212 of the trace portion of the trace portion 21 is formed by the convex outer surface 502 of the cut-off portion 50, and the corner C1 of the trace portion 21 is formed by the corner C2 of the cut-off portion 50.

[0113] The top surface 500 of the cut-off portion 50 is flat and extends horizontally. Therefore, compared to when the top surface 500 is curved or when the top surface 500 extends in a direction intersecting the horizontal, it is possible to prevent the top surface 500 from being locally pressed against the separator 2 (the top surface from contacting one side of the separator 2) during mold clamping. This reduces stress concentration on a portion of the top surface 500, i.e., reduces residual stress concentration on a portion of the bottom surface 210 of the trace portion 21. Furthermore, compared to when the cut-off portion 50 does not have a top surface 500, it is possible to improve the shape precision of the cut-off portion 50, i.e., the trace portion 21.

[0114] The X-direction width (left-right width) W2 between the pair of side surfaces (convex inner surface 501, convex outer surface 502) of the cut-off portion 50 narrows from the parting line PL toward the top surface 500. Therefore, compared to when the X-direction width W2 between the pair of side surfaces is constant in the direction from the parting line toward the top surface, it is possible to alleviate stress concentration at the corner C2 of the cut-off portion 50 during mold clamping. Therefore, it is possible to suppress residual stress concentration at the corner C1 of the trace portion 21.

[0115] Second Embodiment The mold and composite member for a fuel cell of this embodiment differ from the mold and composite member for a fuel cell of the first embodiment in that the cut-off portion and the cavity recess are arranged adjacent to each other in the left-right direction. Also, the convex inner surface of the cut-off portion extends into the cavity recess. Here, only the differences will be described.

[0116] Figure 13 shows a partial cross-sectional view of the mold of this embodiment. Note that parts corresponding to those in Figure 8 are designated by the same reference numerals. As shown in Figure 13, the edge-cutting portion 50 and the cavity recess 51 are disposed adjacent to each other in the left-right direction (X direction). The convex inner surface 501 of the edge-cutting portion 50 straddles the parting line PL from the lower right to the upper left. The convex inner surface 501 extends from the top surface 500 to the interior of the cavity recess 51. In other words, the left end of the convex inner surface 501 of the edge-cutting portion 50 and the right end of the opening edge of the cavity recess 51 overlap each other.

[0117] The mold 5 and composite member for a fuel cell of this embodiment and the mold and composite member for a fuel cell of the first embodiment have similar effects with respect to the parts that have a common configuration. The mold 5 of this embodiment can reduce stress concentration on the opening edge of the cavity recess 51 when the mold is closed, compared to when the convex inner surface 501 does not straddle the parting line PL (does not extend into the cavity recess 51).

[0118] Third Embodiment The mold and composite member for a fuel cell of this embodiment differ from the mold and composite member for a fuel cell of the first embodiment in that no deformation-absorbing recess is provided. Here, only this difference will be described.

[0119] Figure 14 shows a partial cross-sectional view of the mold of this embodiment. Note that parts corresponding to those in Figure 8 are designated by the same reference numerals. As shown in Figure 14, the deformation-absorbing recess 52 shown in Figure 8 is not arranged on the right side (outside in the X direction) of the cut-off portion 50. The mold 5 and composite member for a fuel cell of this embodiment and the mold and composite member for a fuel cell of the first embodiment have similar effects with respect to parts that share a common configuration. With the mold 5 of this embodiment, the surface shape of the mold surface 50U can be simplified compared to when a deformation-absorbing recess is arranged in the second mold 5U.

[0120] <Fourth embodiment> The mold and composite member for a fuel cell of this embodiment differ from the mold and composite member for a fuel cell of the first embodiment in that the cut-off portion and the cavity recess are arranged adjacent to each other in the left-right direction. Also, the convex inner surface of the cut-off portion extends into the interior of the cavity recess. Also, no deformation-absorbing recess is arranged. Here, only the differences will be described.

[0121] FIG. 15 shows a partial cross-sectional view of the mold of this embodiment. Note that parts corresponding to those in FIG. 8 are designated by the same reference numerals. As shown in FIG. 15 , the edge-cutting portion 50 and the cavity recess 51 are adjacently disposed in the left-right direction (X direction). The convex inner surface 501 of the edge-cutting portion 50 straddles the parting line PL from the lower right to the upper left. The convex inner surface 501 extends from the top surface 500 to the interior of the cavity recess 51. In other words, the left end of the convex inner surface 501 of the edge-cutting portion 50 and the right end of the opening edge of the cavity recess 51 overlap each other. The deformation-absorbing recess 52 shown in FIG. 8 is not disposed on the right side (outside in the X direction) of the edge-cutting portion 50.

[0122] The mold 5 and composite member for a fuel cell of this embodiment and the mold and composite member for a fuel cell of the first embodiment have similar effects with respect to the parts that share the same configuration. The mold 5 of this embodiment can reduce stress concentration on the opening edge of the cavity recess 51 during mold clamping, compared to when the convex inner surface 501 does not straddle the parting line PL (does not extend into the cavity recess 51). Furthermore, the surface shape of the mold surface 50U can be simplified, compared to when a deformation-absorbing recess is provided in the second mold 5U.

[0123] <Others> The above describes the embodiments of the mold and the composite member for a fuel cell according to the present disclosure. However, the embodiments are not particularly limited to the above-described embodiments. Various modifications and improvements that can be made by those skilled in the art are also possible.

[0124] FIG. 16 shows a partial top view of a composite member for a fuel cell according to another embodiment. Note that parts corresponding to those in FIG. 2 are designated by the same reference numerals. As shown in FIG. 16 , the gasket placement portion 20, i.e., the gasket 4, extends linearly and band-like. The trace portion 21 surrounds the entire gasket placement portion 20 in an endless annular shape. That is, the cut-off portion 50 of the mold 5 surrounds the entire gasket placement portion 20 in an endless annular shape. Therefore, during the injection process described above, leakage of the raw material G of the gasket 4 can be suppressed around the entire circumference of the cavity recess 51, i.e., the cavity 5M. Thus, the extension shape of the gasket 4 (the shape when viewed from above and below in a plan view, as shown in FIG. 1 ) is not particularly limited. It may be in the form of a strip (such as a straight line, a curved line, or a suitable combination of these shapes), a block (such as a circle, an ellipse, a droplet, a polygon (such as a triangle, a square, or a hexagon), or an irregular shape), or a frame (such as a circular frame, an ellipse, or a polygonal frame).

[0125] The cross-sectional shape of the gasket 4 (the shape in the direction perpendicular to the extending direction of the gasket 4 as shown in FIG. 3 ) is not particularly limited, and may be, for example, a rectangular shape, a trapezoidal shape, an arc shape, a V-shape, a C-shape, a U-shape, or an appropriate combination of these shapes.

[0126] The presence or absence, shape, size, number, etc. of burrs B extending from the gasket seating portion 20 shown in Figure 12 are not particularly limited. As shown in Figure 16, burrs B may not extend from the gasket seating portion 20. Burrs B may extend from one location on the gasket seating portion 20. Burrs B may extend from multiple locations on the gasket seating portion 20. Burrs B may extend from the entire gasket seating portion 20. Burrs B may or may not reach the edge-cutting portion 50 (trace portion 21). Burrs B may extend beyond the edge-cutting portion 50.

[0127] The relative positional relationship between the gasket placement portion 20 and the cut-off portion 50 (tracing portion 21) is not particularly limited. As shown in FIG. 11 , the cut-off portion 50 may be located on both the inside and outside of the frame of the frame-shaped gasket placement portion 20. The cut-off portion 50 may be located only on the inside of the frame of the frame-shaped gasket placement portion 20. The cut-off portion 50 may be located only on the outside of the frame of the frame-shaped gasket placement portion 20. In other words, it is sufficient that the cut-off portion 50 is located on at least one of the outside and inside of the frame of the frame-shaped gasket placement portion 20.

[0128] The extending shape (shape as seen in a plan view from the top and bottom as shown in FIG. 1 ) of the trace portion 21 (the same applies to the cut-off portion 50 and the deformation-absorbing recess 52) is not particularly limited. It may be strip-shaped (straight, curved, or a shape that is an appropriate combination of these shapes), block-shaped (circular, elliptical, droplet-shaped, polygonal (triangular, rectangular, hexagonal, or the like), irregular, or frame-shaped (circular, elliptical, or polygonal frame).

[0129] The cross-sectional shape (the shape in the direction perpendicular to the extending direction of the gasket 4, as shown in FIG. 3 ) of the trace portion 21 (as well as the cut-off portion 50 and the deformation-absorbing recess 52) is not particularly limited. For example, it may be rectangular, trapezoidal, arc-shaped, V-shaped, C-shaped, U-shaped, or an appropriate combination of these shapes.

[0130] The extending shape of the gasket placement portion 20 (similar to the cavity recess 51 and the gasket 4) and the extending shape of the trace portion 21 (similar to the cut-off portion 50 and the deformation-absorbing recess 52) may be the same or different. For example, the gasket placement portion 20 and the trace portion 21 may both extend in a frame shape. Alternatively, the gasket placement portion 20 may extend linearly, and the trace portion 21 may extend in a frame shape (endless ring) around the gasket placement portion 20.

[0131] The number of gasket placement portions 20 (same for cavity recesses 51 and gaskets 4) and the number of trace portions 21 (same for cut-off portions 50 and deformation-absorbing recesses 52) may be the same or different. A single trace portion 21 may be arranged for a single gasket placement portion 20. Multiple trace portions 21 may be arranged for a single gasket placement portion 20. A single trace portion 21 may be arranged for multiple gasket placement portions 20. For example, a single frame-shaped trace portion 21 that comprehensively surrounds multiple island-shaped gasket placement portions 20 may be arranged for multiple island-shaped gasket placement portions 20.

[0132] The Y-direction protrusion amount E, X-direction width F, W1, W2, inclination angles α1, α2, β1, β2, and intersection angles θ1 and θ2 shown in FIG. 8 are not particularly limited. The inclination angles α1, α2, β1, and β2 may each be 60° or greater or less than 60°. The inclination angles α1 and β1 may be the same or different. The inclination angles α2 and β2 may be the same or different. The intersection angles θ1 and θ2 may or may not be within the range of 120° or greater and 150° or less. The intersection angles θ1 and θ2 may each be an obtuse angle, a right angle, or an acute angle.

[0133] The shapes of the bottom surface 210, the trace portion concave inner surface 211, the trace portion concave outer surface 212, the top surface 500, the convex inner surface 501, and the convex outer surface 502 are not particularly limited. They may be flat, curved, or a suitable combination of these shapes. Rounded chamfers may be arranged instead of the corners C1 and C2. The above-described shapes of the trace portion 21 and the edge-cutting portion 50 can be applied to the shape of the deformation-absorbing recess 52. The deformation of the adjacent portion 22 during mold clamping shown in FIG. 12 may or may not remain in the separator 2 after mold opening. In other words, the deformation of the adjacent portion 22 during mold clamping may be plastic deformation or elastic deformation.

[0134] The arrangement direction of the first mold 5D and the second mold 5U of the mold 5 shown in Figure 5 (the opening and closing direction of the mold 5) is not particularly limited. It may be vertical, horizontal, or a direction intersecting the vertical and horizontal directions. In the injection step, the first mold 5D may be fixed and the second mold 5U may be movable. Conversely, the first mold 5D may be movable and the second mold 5U may be fixed.

[0135] The material of the mold 5 is not particularly limited. It may be corrosion-resistant steel, carbon tool steel, alloy tool steel, high-speed tool steel, as-rolled steel, pre-hardened steel, quenched steel, quenched and tempered steel, aging-treated steel, or the like. The material of the separator 2 is not particularly limited. It may be a resin, metal, or the like that is conductive and non-corrosive. Examples include stainless steel, titanium, copper, magnesium, aluminum, carbon, graphite, ceramics, and conductive resins (thermoplastic or thermosetting resins containing carbon, graphite, polyacrylonitrile-based carbon fiber, or the like).

[0136] The material of the gasket 4 is not particularly limited. It is sufficient that the elastomer has insulating properties and rubber elasticity after curing. It is sufficient that the raw material G (before curing) has fluidity. In addition to the rubber component, the gasket 4 may contain a crosslinking agent, a co-crosslinking agent, a processing aid, a softener, a reinforcing material, and the like. Suitable rubber components include VMQ (silicone rubber), as well as silicone rubbers other than VMQ (such as PVMQ (phenyl vinyl methyl silicone rubber) and FVMQ (fluoro vinyl methyl silicone rubber)), EPDM (ethylene propylene diene rubber), and FKM (fluoro rubber). When liquid silicone rubber is used as the raw material G, the type of liquid silicone rubber is not particularly limited. It may be a one-component type or a two-component type. It may also be a room temperature curing type or a heat curing type.

[0137] In the above embodiment, a composite member for a fuel cell has been described as an example of the composite member for an electrochemical device of the present disclosure. However, the type of electrochemical device is not particularly limited. The electrochemical device may be any device that converts chemical energy into electrical energy or electrical energy into chemical energy. Examples of electrochemical devices include fuel cells, secondary batteries, and water electrolysis devices.

[0138] In the above embodiment, a method for manufacturing a composite member for a fuel cell, which includes an injection step and a vulcanization step (crosslinking step), has been described as an example of a method for manufacturing a composite member for an electrochemical device according to the present disclosure. However, the method for manufacturing a composite member for an electrochemical device according to the present disclosure is not particularly limited. For example, a method for manufacturing a composite member for an electrochemical device, which includes an injection step and a vulcanization integration step, may also be used. In this case, a gasket may be molded in the injection step, and the gasket may be laminated on a substrate and then vulcanized and cured in the vulcanization integration step, thereby integrating the gasket and the substrate.

[0139] 1: Composite member for fuel cell (composite member for electrochemical device), 2: Separator (substrate), 2D: lower surface, 2U: upper surface (surface), 20: Gasket placement portion, 21: Trace portion, 210: bottom surface, 211: Trace portion concave inner surface, 212: Trace portion concave outer surface, 22: Adjacent portion, 23: Manifold, 24: Convex portion, 4: Gasket, 5: Mold, 5D: First mold, 50D: Mold surface, 5M: Cavity, 5U: Second mold, 50U: Mold surface, 50: Cut-off portion, 500: Top surface, 501: Convex inner surface, 502: Convex Outer surface, 51: cavity recess, 52: deformation absorbing recess, 520: bottom surface, 521: recessed inner surface, 522: recessed outer surface, 53: manifold protrusion, 54: recess, α1: inclination angle, α2: inclination angle, β1: inclination angle, β2: inclination angle, θ1: intersection angle, θ2: intersection angle, A: X-direction central axis, B: burr, C1: corner, C2: corner, D: apparent undercut depth, E: Y-direction protrusion amount, F: X-direction width, G: raw material, H: frame, PL: parting line, W1: X-direction width, W2: X-direction width

Claims

1. A mold for insert molding used to mold a gasket on a thin plate-like substrate placed within the mold, the mold having a cut-off portion that suppresses burrs from the gasket, wherein the extension direction of a parting line of the mold is the X direction, the opening and closing direction of the mold is the Y direction, the side closer to the cavity for molding the gasket in the X direction is the inner side in the X direction, and the side opposite the inner side in the X direction in the X direction is the outer side in the X direction, the mold comprising: a first mold on which the substrate is placed; and a second mold placed opposite the first mold in the Y direction and having the cut-off portion and a cavity recess that is placed inside the cut-off portion in the X direction and defines the cavity, wherein the cut-off portion has a planar top surface that protrudes toward the substrate from the parting line and extends in the X direction, a convex inner side surface that is placed inside the top surface in the X direction, and a convex outer side surface that is placed outside the top surface in the X direction, the mold characterized in that the width in the X direction between the convex inner side surface and the convex outer side surface narrows in the direction from the parting line toward the top surface.

2. The mold according to claim 1, wherein the convex inner surface and the convex outer surface are each flat.

3. A mold according to claim 2, wherein the angle of intersection between said convex inner surface and said convex outer surface is an obtuse angle.

4. A mold according to claim 3, wherein the intersection angle is between 120° and 150°.

5. A mold according to claim 2, wherein the angle of inclination of the convex inner surface relative to the Y direction is the same as the angle of inclination of the convex outer surface relative to the Y direction.

6. A mold according to claim 1, wherein the convex inner side surface extends from the top surface to the inside of the cavity recess, straddling the parting line.

7. A mold according to claim 1, wherein the second mold is positioned outside the cutting portion in the X direction and has a deformation-absorbing recess that absorbs deformation of the base material when the top surface is pressed against the base material.

8. A mold as described in claim 7, wherein the deformation-absorbing recess has a planar bottom surface that is recessed into the second mold relative to the parting line and extends in the X direction, a concave inner side surface that is located on the inside of the bottom surface in the X direction, and a concave outer side surface that is located on the outside of the bottom surface in the X direction, and the X-direction width between the concave inner side surface and the concave outer side surface narrows in the direction from the parting line toward the bottom surface.

9. A mold as set forth in claim 8, wherein the cut-off portion and the deformation-absorbing recess are arranged adjacent to each other, and the convex outer surface and the concave inner surface are smoothly connected from the inside in the X direction toward the outside in the X direction.

10. A mold according to claim 1, wherein the amount of protrusion of the top surface in the Y direction relative to the parting line is 10 μm or more and 100 μm or less.

11. The mold according to claim 1, wherein the width of the top surface in the X direction is 10 μm or more and 500 μm or less.

12. A mold according to claim 1, wherein the cut-off portion is disposed at a predetermined distance outward in the X direction from the cavity recess.

13. A composite member for electrochemical devices comprising a substrate and a gasket arranged on the surface of the substrate, wherein the extending direction of the surface is the X direction, the stacking direction of the substrate and the gasket is the Y direction, the side closer to the gasket in the X direction is the inner side in the X direction, and the side opposite the inner side in the X direction is the outer side in the X direction, the substrate has on its surface a concave trace portion and a gasket arrangement portion arranged on the inner side of the trace portion in the X direction and on which the gasket is arranged, the trace portion having a planar bottom surface, a trace portion concave inner side surface arranged on the inner side of the bottom surface in the X direction, and a trace portion concave outer side surface arranged on the outer side of the bottom surface in the X direction, and the width in the X direction between the trace portion concave inner side surface and the trace portion concave outer side surface narrows in the direction from the surface to the bottom surface.

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