JP2002151096A - Production process of fuel cell separator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a production process of a fuel cell separator, by which a gas passage-integrated separator can be efficiently produced with high working precision. SOLUTION: A conductive separator base B is vertically arranged between a pair of working electrodes 30 provided on left and right sides. An architrave- like shielding material 40 is arranged between a surface of the separator base B to be worked an each working electrode 30. The shielding material 40 shields entering of electric lines of force derived from a difference in form or area between the surface of the separator base B to be worked and the working electrode 30 to form a parallel electric field between their opposing surfaces. Electricity is fed to the working electrodes 30 and separator base B in a state that an electrolyte has been sprayed and fed between the opposing surfaces thereof, thereby electrolytically working recesses for forming gas passages in the surfaces of the separator base B to be worked.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a fuel cell separator having an integrated gas flow path.

[0002]

2. Description of the Related Art In general, a fuel cell that generates power by receiving a supply of fuel gas is formed by stacking a plurality of battery cells.
A separator for separating the two is interposed between the adjacent battery cells, and this separator also plays a role as a flow path component for forming a gas flow path for supplying a fuel gas or the like to each cell. . One of the techniques for forming a concave portion (a groove or a concave portion) serving as a gas flow path in such a gas flow path-integrated separator is an electrolytic processing method in which a metal plate serving as a separator base material is subjected to electrolytic etching.

In a conventional electrolytic processing method, a metal plate serving as a separator base material and a processing electrode having a concavo-convex shape corresponding to a pattern shape of a gas flow path are formed in a tank filled with an etching solution such as an electrolytic solution. They are arranged facing each other. Then, in a state where the electrolytic solution is interposed between the metal plate and the processing electrode, the metal plate is used as a positive electrode and the processing electrode is used as a negative electrode to supply power to the metal plate and a part of the metal plate is electrolytically eluted to form a processing electrode. The gas flow pattern corresponding to the uneven shape is engraved on the metal plate.

[0004]

By the way, for example, FIG.
It is assumed that a voltage is applied between the positive electrode 51 and the negative electrode 52 under the condition that the shape and area of the two opposing electrodes 51 and 52 are the same as shown in FIG. At this time, both electrodes 5
An electric field corresponding to the distance between the two is formed between the first and second electric fields 52. However, almost all of the electric lines of force in the electric field are parallel to each other, and there is no uneven distribution of the electric lines of force. That is, both electrodes 5
The magnitude of the parallel electric field generated between the opposing surfaces 1 and 52 is made uniform.

On the other hand, as shown in FIG. 11, when a voltage is applied between the positive electrode 51 and the negative electrode 52 in a situation where the two opposing electrodes 51 and 52 have similar shapes but different areas. think of. At this time, the lines of electric force in the electric field are substantially parallel at the center of each electrode, but the lines of electric force are curved at the peripheral portion (or end) of each electrode so as to connect both peripheral portions. I do. As a result, the distribution density of electric lines of force (that is, the magnitude of the electric field) differs between the central part and the peripheral part in each electrode. More specifically, in the positive electrode 51 having a small area shown in FIG. 11, the density of lines of electric force is higher in the peripheral part than in the central part.

Now, what happens if the situation shown in FIG. 11 occurs in the electrolytic processing of the fuel cell separator base material? For example, it is assumed that the negative electrode 52 in FIG. 11 is a processing electrode and the positive electrode 51 is a metal plate to be subjected to electrolytic processing. Then, the peripheral portion of the metal plate is placed in an electric field that is relatively stronger than the central portion. Considering that the etching activity of the electrolytic solution depends on the strength of the electric field, there is no doubt that the peripheral portion of the metal plate tends to be deeper than the central portion. In fact, such a tendency is confirmed in a prototype experiment described later (see a comparative example in FIG. 8). Therefore, when the shape or the area is different between the separator base material and the processing electrode, the processing accuracy of the concave portion (especially, the accuracy of the engraving depth at the peripheral portion or the end portion) is reduced in the separator base material to be processed. There is a problem of lowering.

In order to avoid or reduce the concentration of the lines of electric force in the peripheral portion of the separator substrate, it is conceivable to secure a large distance between the separator substrate and the processing electrode. Accordingly, when the electric field is weakened, the efficiency of electrolytic processing is deteriorated, and the productivity is reduced. Also, in a state where the distance between the poles is wide and the electric resistance between the poles is large, if the amount of power supply to the poles is increased to increase the efficiency of electrolytic processing, heat generation in the separator base material becomes remarkable and a new phenomenon called thermal deformation occurs. It creates problems. Fuel cell separators are increasingly required to be thinner, and there is a situation in which an extremely thin separator substrate that is easily deformed by heat must be used.

An object of the present invention is to provide a method of manufacturing a fuel cell separator capable of efficiently producing a gas flow path integrated type separator with high processing accuracy. In addition, it is an object of the present invention to make it possible to set the distance between the separator substrate and the processing electrode as small as possible.

[0009]

According to the first aspect of the present invention, there is provided a method of manufacturing a fuel cell separator having a gas flow path, wherein a conductive separator having a shape or an area different from that of the processed electrode is provided. Opposing the processing surfaces of the base material at a predetermined interval, and opposing the processing electrodes and the separator base material by blocking the wraparound of lines of electric force resulting from the difference in shape or area between the processing surfaces of the separator base material. A step of arranging a shielding material for forming a parallel electric field between the surfaces between the processing electrode and the separator base, and a step of disposing the electrolyte between the facing surfaces of the separator base and the processing electrode. And a step of electrolytically processing the concave portion for forming the gas flow passage on the surface to be processed of the separator base material by supplying power to the separator substrate.

According to this method, even if the processing electrode as one electrode in electrolytic processing and the surface to be processed of the conductive separator base material as the other electrode are different in shape or area, even if they are different from each other. With the shielding material arranged, it is possible to form a parallel electric field between the opposing surfaces by blocking the wraparound of the lines of electric force resulting from the difference in shape or area. For this reason, it is possible to avoid uneven distribution of electric energy distribution such as locally increasing current density in the electrolytically processed portion of the surface to be processed of the separator base material, and to improve processing accuracy by maintaining uniformity of electrolytic processing. Become.

By the way, FIG. 1 visualizes this idea.
2. In FIG. 12, for convenience, the positive electrode side is illustrated as a small area and the negative electrode side is illustrated as a large area. However, the situation is the same even if the area relationship is reversed. The shielding material disposed between the positive and negative electrodes matches the shape and area of the exposed surfaces facing each other on the positive electrode side and the negative electrode side, and creates a situation equivalent to that of FIG. 10 as far as the electric field is formed between the positive and negative electrodes. Therefore, it is possible to avoid a situation where the lines of electric force are concentrated on the peripheral portion or the end portion of the processing surface of the conductive separator base material.

It is preferable that the thickness of the shielding material is set so as to substantially correspond to the distance (separation length) between the processing electrode and the separator base material. In this case, the formation of the parallel electric field is made more reliable by effectively preventing the wraparound of the lines of electric force.

According to a second aspect of the present invention, in the method of manufacturing a fuel cell separator according to the first aspect, the shielding member is made of an electrically insulating material.

Since the shielding member is made of an electrically insulating material, the formation of an electric field in the space occupied by the shielding member is prevented, or the electric field in the occupied space is extremely weakened. In this sense, the smaller the electric resistance value of the electric insulating material used, the more preferable. Since the shielding material is also exposed to the electrolytic solution during the electrolytic processing, it is more preferable that the shielding material is made of a material having both corrosion resistance and heat resistance.

According to a third aspect of the present invention, in the method of manufacturing a fuel cell separator according to the first or second aspect, the shielding member has the same shape as the surface to be processed of the separator base material and the surface facing the processed electrode. It is characterized in that it is interposed between the processing electrode and the separator base material so that an opposing relationship having the same area can be established.

This clarifies one condition for forming a parallel electric field between the surface to be processed of the separator base material and the opposite surface of the processing electrode, assuming the situation as shown in FIG. is there. However, a shielding material capable of establishing an opposing relationship in which the surface to be processed of the separator base material and the opposing surface of the processing electrode have the same shape and the same area means that the shielding material has a frame shape as shown in FIG. It is not meant to be limited.

According to a fourth aspect of the present invention, in the method for manufacturing a fuel cell separator according to any one of the first to third aspects, the electrolytic processing on the surface to be processed of the separator base material is performed along the processed electrode. The method is performed while the separator base material and the shielding material are synchronously moved.

This relates to a production system in which electrolytic processing of a large number of separator substrates is carried out in a flowable manner. In a production system in which electrolytic processing is performed while moving the separator base material along the processing electrode, it is assumed that the processing electrode extends in the moving direction of the separator base material. In the electrolytic processing at that time, in particular, it is necessary to avoid the concentration of the lines of electric force at the front side and the rear side in the moving direction of the surface to be processed of the separator base material. There is a need for lumber. The technical significance of the contents of claim 4 will be further clarified in embodiments of the invention described later.

According to a fifth aspect of the present invention, in the method of manufacturing a fuel cell separator according to any one of the first to fourth aspects, the surface to be processed of the separator substrate is partially subjected to masking and the electrolytic process is performed. In the processing step, an electrolytic solution is jetted and supplied from a direction substantially perpendicular to the processed surface of the masked separator base material to interpose an electrolytic solution between the processed surface and the processing electrode, and Is characterized in that the non-masking portion is electrolyzed to form a gas flow path forming concave portion.

According to this method, since the electrolytic solution is jetted and supplied from a direction substantially perpendicular to the processing surface of the partially masked separator substrate, the distance between the processing surface and the processing electrode is reduced. The electrolytic solution can be immediately spread over the region, and the entire surface to be processed can be uniformly covered with the electrolytic solution. In particular, since the supply direction of the electrolytic solution is substantially perpendicular to the surface to be processed, it is possible to directly feed the electrolytic solution also into the central region of the surface to be processed, and the supply efficiency of the electrolytic solution is extremely high. For this reason, a sufficient amount of fresh electrolytic solution is supplied one after another between the surface to be processed and the processing electrode in combination with the injection and supply of the electrolytic solution, and unnecessary electrolytic products are formed on the surface to be processed. To promote the electrochemical reaction in the non-masked portion of the work surface. Therefore, in the non-masking portion of the surface to be processed, a desired recess for forming a gas flow path is formed in a relatively short time with high energy efficiency.

The masking on the separator substrate is as follows.
It simply refers to a material or member that is coated or adhered to a part of the surface to be processed in order to prevent contact with the electrolytic solution. Therefore, the shielding material for blocking the wraparound of the electric field lines and the masking on the separator substrate have different technical significances, and both should be clearly distinguished.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. (Outline of Fuel Cell Separator Manufacturing Apparatus) As shown in FIG. 1, an electrolyte storage tank 11 is provided below the fuel cell separator manufacturing apparatus. The storage tank 11 is provided with an air-cooled or water-cooled temperature controller (not shown), and the electrolyte stored in the storage tank 11 is maintained at a substantially desired temperature. A double tank type recovery tank 12 is provided above the storage tank 11, and a vertical communication path 13 for returning the electrolyte from the recovery tank 12 to the storage tank 11 is provided in the center of the bottom wall of the recovery tank 12. Have been.

As shown in FIGS. 1 and 2, a pair of left and right sparger boxes 14 and 15 are arranged in the collection tank 12 in parallel. Although these sparger boxes 14 and 15 are located at the same height, they are arranged at a distance from each other in the horizontal direction, and electrode-facing nozzles 30 (hereinafter, referred to as “electrode nozzles”) as processing electrodes are provided at opposing portions. Is provided. Although the detailed structure of the electrode nozzle 30 will be described later, as shown in FIG. 4, a plurality of slit-shaped injection ports 31 for injecting the electrolytic solution are provided. Inside each of the sparger boxes 14 and 15, an internal passage 16 for guiding the electrolytic solution from below to above is formed, and this internal passage 16 communicates with each of the slit-shaped injection ports 31. Further, the internal passages 16 of the sparger boxes 14 and 15 respectively
It is connected to the storage tank 11 via a supply passage 17 provided with a pump P (preferably a chemical pump) and a filter F on the way. The storage tank 11 is operated by the action of the pump P.
The electrolyte stored in the supply passage 17 is pumped up.
And, it is supplied to each slit-shaped injection port 31 of the electrode nozzle 30 through the internal passage 16. The filter F removes impurities mixed in the electrolytic solution and unnecessary electrolytic products. In addition, the storage tank 11, the supply passage 17, and the pump P constitute an electrolyte supply means, and the recovery tank 12 and the vertical communication path 13 constitute an electrolyte recovery means.

A guide rail 21 is provided above the sparger boxes 14 and 15 so as to extend in a direction perpendicular to the plane of the drawing, as shown in FIG. This guide rail 21
, A work holder 22 is provided so as to be able to reciprocate. As shown in FIG. 3, the work holder 22 is fixed to a chain or a part of a wire 23 having an endless track,
It is possible to reciprocate on the guide rail 21 by multiplying the transfer of the chain or wire 23 in the forward or reverse direction by the drive motor 24. As shown in FIGS. 1 and 2, the work holder 22 is a separator base material B as a flat work.
, And hold the separator base material B in such a manner that it is suspended in the vertical direction. The separator base material B held by the work holder 22 includes a pair of left and right electrode nozzles 3.
0 is disposed substantially at the center between opposing surfaces of the work holder 22.
Move between the two electrode nozzles 30 with the movement of the nozzle. That is, the guide rail 21, the chain or the wire 23, and the drive motor 24 constitute a transfer unit operatively connected to the work holder 22.

As shown in FIG. 1, the manufacturing apparatus includes a DC power supply 26 as a power supply. The positive electrode of the DC power supply 26 is connected to the work holder 22 via a flexible power supply line 27. On the other hand, the negative electrode of the DC power supply 26 is connected to the upper ends of the corresponding electrode nozzles 30 via two flexible power supply lines 28. An electric potential is applied between the electrode nozzle 30 and the separator base material B by the power supply from the DC power supply 26, and an electric field is formed between the processing surface of the separator base material B and the opposing surface of each electrode nozzle 30. You.

FIG. 4 shows a surface-facing electrode nozzle 30 which faces the surface to be processed of the separator base material B at a predetermined interval.
The outline of is shown. As shown in FIG. 4, a plurality of slit-shaped injection ports 31 (in this example, nine) are formed on the facing surface 32 of each electrode nozzle 30. Each slit-shaped injection port 31
Extend in the vertical direction, and the length h in the vertical direction matches the height h (see FIG. 2) of the processed portion of the separator base material B. The width of each slit-shaped injection port 31 is 0.5 mm or more.
It is set in the range of 2.5 mm, preferably about 1.5 mm. As described above, each slit-shaped injection port 31 communicates with the internal passage 16 of the corresponding sparger box. The electrode nozzle 30 is attached to the sparger box with a high sealing property so that the electrolytic solution does not leak to the other than the supply to the injection ports 31 via the internal passages 16. Also, between the slit-shaped injection ports 31 adjacent to the facing surface 32 of each electrode nozzle 30,
An escape groove 33 is provided. The plurality of escape grooves 33 captures the electrolyte flowing to the left and right in search of an escape spot when the electrolyte is injected from each of the slit-shaped injection ports 31 toward the separator base material B, and enters the recovery tank 12. Promote smooth discharge. In this example, the depth of the escape groove 33 is set to about 20 mm.

On the facing surface 32 of each electrode nozzle 30,
A region above an imaginary line connecting the upper edges of the slit-shaped nozzles 31 (an upper region indicated by oblique lines in FIG. 4) and a region below the imaginary line connecting the lower edges of the slit-shaped nozzles 31 (shaded lines in FIG. 4) (Lower regions indicated by) are provided with thin masks 34 and 35, respectively. These masks 34 and 35 seal as much as possible a region in which an electric field does not need to be formed between the separator base material B as a work, and an exposed region (substantially a negative electrode) along the slit-shaped injection port 31 is formed. Work surface of separator base material B (substantially positive electrode)
This is for optimizing the electric field formed between them when they face each other.

The electrode nozzle 30 is made of a material having both conductivity and corrosion resistance. Examples of such an electrode constituent material include platinum, graphite, and stainless steel or titanium-based metal. One that has been subjected to platinum plating is given. A plurality of work guides 36 are arranged in a row in the horizontal direction at an upper side position of the masking 34, and a work guide 37 extending in the horizontal direction is provided at a lower side position of the masking 35. These work guides 36 and 37 come into contact with the surface of the work during electrolytic etching to guide the movement of the work and also support the work from the side to prevent the work from wobbling. In this example, the work guides 36 and 37 are provided on the electrode nozzle 30, but they have no relation to the function as an electrode.

When actually constructing a fuel cell separator manufacturing line, a plurality of similar sparger box pairs are prepared by using the above-mentioned pair of left and right sparger boxes 14 and 15 as a set, and they are connected in series. , A straight path for transporting the separator base material B is set. Then, along the linear path, the guide rail 21
And a plurality of work holders 22 are run thereon.
By doing so, it becomes possible to carry out the electrolytic etching while conveying a large number of separator base materials B in one direction, and to perform the work in an operative manner.

(Procedure for Manufacturing Fuel Cell Separator)
A procedure for manufacturing a fuel cell separator integrated with a gas flow path using the above manufacturing apparatus will be described. In the following description, well-known and commonly used procedures for manufacturing a fuel cell separator will not be described or will be described only briefly.

(Preparation Step) A separator base material B as a starting material for forming a fuel cell separator integrated with a gas flow path is prepared, for example, by cutting a metal plate material. The separator substrate B is made of a conductive material. Examples of usable conductive materials include aluminum-based, stainless steel-based, titanium-based, and copper-based metals or alloys. The separator base material B is preferably a flat metal plate material. In this example, a stainless steel plate (SUS304) having a thickness of 1.5 mm, a width of 300 mm, and a height of 430 mm was used as the separator base material B. The processing surfaces (front and back surfaces) of the separator base material B were subjected to masking after pretreatment such as degreasing and washing. As shown in FIG. 1, FIG. 2 and FIG.
Is applied to a portion (that is, a non-etched portion) that is left as a convex portion or a land portion when forming a gas flow path. As the masking material for the base material B, a general masking material for electric field or electroless plating can be used. In forming the mask, for example, a method of diluting an acid-resistant etch resist with a predetermined diluting solvent to have an appropriate viscosity, drying the screen on each processing surface of the separator substrate B after screen printing, or attaching a masking tape. An approach is taken. Note that a UV-curable resist may be used instead of the acid-resistant etch resist.

Further, as shown in FIGS. 2, 5 and 6,
An electric field shielding material 40 was adhered and fixed to each surface to be processed of the separator substrate B to which the masking M was applied, using a double-sided tape or the like. The shielding member 40 has an overall shape like a frame, and includes a front side portion 40a, a rear side portion 40b, an upper side portion 40c, and a lower side portion 40d in the work conveyance direction. At the center of the shielding member 40, there is an opening 41 having a substantially square shape. Inner peripheral edge 42 of shielding material 40 defining this opening 41
Corresponds to the outer peripheral edge of the non-masking portion N (that is, the exposed portion to be etched) of the separator base material B. For this reason, the shielding material 4
When 0 is stuck, the entire non-masking portion N on each processing surface is exposed from the opening 41 of the shielding member 40 as it is.

As shown in FIG. 6, the thickness of each shielding member 40 is set to be substantially equal to the distance between the facing surfaces of the separator base material B and the electrode nozzle 30. That is, the shielding material 40 almost completely fills the space between the separator base material B and the electrode nozzle 30 in a state surrounding the non-masking portion N on the processing surface. Also in this case, it is preferable that the shielding member 40 is not in contact with the opposing surface 32 of the electrode nozzle 30, but it is necessary to synchronize (or move integrally) the separator base material B and the shielding member 40 along the electrode nozzle 30. The shielding member 40 may be brought into contact with the facing surface 32 of the electrode nozzle 30 as long as no trouble occurs.

The shielding member 40 is made of an electrically insulating material to serve as a member for partially shielding the electric field formed between the positive and negative electrodes. As the electric insulating material to be used, a material having a volume resistivity of 10 ¹⁴ (Ω · cm) or more is preferable. For example, heat-resistant polyvinyl chloride (P
VC). The masking M thus prepared and the separator base material B with the shielding member 40 are suspended in the vertical direction with the upper end portions being held by the work holder 22.

On the other hand, in the storage tank 11, an electrolytic solution, which is a processing solution for electrolytic etching, is prepared. As the electrolytic solution, those generally known as electrolytic etching treatment solutions can be used. For example, a group consisting of nitric acid, hydrofluoric acid, phosphoric acid, hydrochloric acid, and sulfuric acid depending on the type of metal material to be etched. More than one kind of acid is selected and mixed to prepare a mixed acid solution, and a small amount of an additive for adjusting an etching rate or the like is added thereto.
(About 1-0.5 ml) is recommended. Alternatively, a sodium nitrate solution may be used as the electrolyte. The temperature of the electrolytic solution can be arbitrarily selected in the range of 30 ° C. to 65 ° C., but since the temperature greatly affects the etching process, it is preferable to keep the temperature as constant as possible during electrolytic etching.

(Electrochemical Machining Step) The masking M and the separator base material B with the shielding material 40 held by the work holder 22 are driven by the drive motor 24 so that the pair of electrode nozzles provided in the sparger boxes 14 and 15 are disposed. 30 (see FIGS. 1, 5 and 6). When the separator base material B is disposed between the two electrode nozzles 30, the distance between each processing surface of the separator base material B and the facing surface 32 of the electrode nozzle is preferably 0.05 mm to 30 mm (more preferably 0 mm to 30 mm). .1 to 0.5 mm). If this interval is less than 0.05 mm, sparks are likely to occur between the separator base material B and the electrode nozzles 30, and the processing accuracy is rather reduced. On the other hand, if the distance exceeds 30 mm, the electrical resistance increases, and the electrolytic etching efficiency decreases significantly.

When the separator base material B enters between the two electrode nozzles 30, the electrolyte solution is sprayed and supplied from each electrode nozzle 30 to each surface to be processed of the separator base material B, and the DC power source 26 supplies the separator base material. Electric current is supplied to the material B and the electrode nozzle 30. The current density of the DC current supplied from the DC power supply 26 during electrolytic etching is preferably 0.5 to 100.0 A / cm ² (more preferably 1 to 10 A / cm ² ).
0 to 45 A / cm ² ). Power supply time (that is, the time during which the separator base material B exists between the two electrode nozzles 30)
Is appropriately changed according to the current density and the desired groove depth.

The injection pressure and the injection flow rate of the electrolyte from the electrode nozzle 30 can be arbitrarily set by adjusting the pumping capacity of the pump P. The electrolyte is injected from each slit-shaped injection port 31 of the electrode nozzle 30 in a direction substantially perpendicular to the surface to be processed of the separator base material B (the horizontal direction in FIG. 1). This injection is performed simultaneously from the two left and right electrode nozzles 30. As shown in FIGS. 4 and 5, each slit-shaped injection port 31 extends in the vertical direction, and a plurality of slit-shaped injection ports 31 are provided at predetermined intervals in the horizontal direction (the direction of transport of the separator base material B). Therefore, most of the electrolyte injected from each of the slit-shaped injection ports 31 spreads right and left in search of an escape place rather than flowing down as it hits the surface to be processed, and enters the escape groove 33. The electrolyte that has entered the escape groove 33 flows vertically down the escape groove 33 and is collected in the collection tank 12.

As described above, the electrolytic solution jetted and supplied from the left and right electrode nozzles 30 to the left and right surfaces to be processed of the separator substrate B immediately (or in a very short time) spreads over the entire surface to be processed. It is widely used for electrolytic etching. Also, electrolytic products generated by electrolytic etching,
It is swept away by the electrolytic solution injected and supplied from the electrode nozzle 30 one after another, and does not stay between the surface to be processed and the electrode nozzle 30. Therefore, electrolytic etching and electrolytic polishing of the surface to be processed with the electrolytic solution are performed with high efficiency.

(Post-Processing Step) After the electrolytic etching, the separator base material B is removed from the work holder 22,
Alternatively, while the line is mounted on the work holder 22 to which power is not supplied, cleaning for removing the attached electrolytic solution is performed, and further, processing for removing the shielding member 40 and the masking M is performed. After the masking M has been removed, a concave portion (a groove or a concave portion) having a desired depth is formed in the non-masking portion of the separator base material B, thereby providing a flow path integrated type separator having a desired form. Excellent gloss was observed on the bottom surface of the concave portion, and the bottom surface and other exposed surfaces were subjected to electrolytic polishing simultaneously with the intended electrolytic etching.
The thus obtained separator integrated with a flow path is subjected to press working or the like for finally adjusting its shape, if necessary.

FIG. 7 shows an example of a fuel cell separator manufactured using the present method. As shown in FIG. 7, a plurality of gas manifolds 51A, 51B, 52A, 52B that penetrate in the stacking direction when a large number of separators are stacked are provided around the fuel cell separator. Further, a groove pattern 53 forming a gas flow path meandering in an S-shape is provided in the front central region of the separator of FIG. 7 so as to communicate a pair of gas manifolds 51A and 51B separated from each other. The groove pattern 53 as the gas flow path forming concave portion is formed by the electrolytic processing as described above.

(Effects of Shielding Material 40 in Electrochemical Processing)
As shown in FIGS. 5 and 6, in the above-described electrolytic processing step, the frame-shaped shielding member 40 that moves integrally with the separator base material B always directly faces the non-masking portion N of each processing surface. An area surrounding the electrode nozzle facing surface 32 is more nearly covered than a partial area (area R in FIG. 6). That is, since the shielding member 40 having a thickness equivalent to the separation length between the separator base material B and the electrode nozzle 30 is interposed therebetween, the electrode directly faces the non-masking portion N of each processing surface. The shape and area of the partial region R of the nozzle facing surface 32 are
Non-masking portion N exposed from opening 41 of shielding material 40
A situation that matches the shape and area of the For this reason,
The electric field in the inner space of the frame-shaped shielding member 40 has a form of a parallel electric field in which almost all lines of electric force (indicated by arrows in FIG. 6) are orthogonal to the surface to be processed and the electrode nozzle facing surface 32. At least, there is almost no wraparound of the lines of electric force connecting the peripheral portion of the non-masking portion N and the region other than the region R of the electrode nozzle 30. Therefore, in the non-masking portion N facing the region R of the electrode nozzle 30 in a one-to-one correspondence, there is no uneven distribution of the current density in the peripheral portion or the end portion, and the current density is made uniform over almost the entire surface. Is done. Therefore, even if the non-masking portion N is subjected to electrolytic processing, the groove depth does not vary depending on the location.

Regarding this point, the effectiveness of the shielding member 40 has been confirmed by trial production experiments. In the prototype experiment, SUS3
The case where electrolytic processing was performed on the stainless steel sheet No. 04 using the above-mentioned manufacturing apparatus and the above-mentioned shielding material 40 (Example), and the case where electrolytic processing was performed without using the above-mentioned shielding material 40 (Comparative Example) The depths of the grooves (recesses) obtained by electrolytic processing were measured for and. That is, the processing conditions other than the presence or absence of the shielding material 40 were exactly the same for both. The processing conditions in the trial production experiment were as follows: the distance between the positive and negative electrodes was 2.7 mm, the current density was 5.0 A / cm ² , and the power supply time was 20 minutes. The measured groove depth refers to the vertical distance from the original surface (reference surface) of the stainless steel plate before processing to the bottom surface of the groove formed by electrolytic processing as shown in FIG. The measurement points are six points a to f shown in FIG.
Located at the end of The remaining measurement points b, c, d, e and f
Was selected at predetermined intervals (approximately 2 mm intervals) from the measurement point a.

FIG. 8 is a graph in which the measurement results of the groove depth in the example and the comparative example are plotted for each measurement point. As can be seen from FIG. 8, in the example using the shielding member 40, the depth could be almost the target value (0.38 mm in this example) at any of the measurement points. The variation in the groove depth at the six measurement points a to f in the example was within 2% of the target value, and the difference in the groove depth depending on the position was hardly observed. On the other hand, in the comparative example in which the shielding material 40 was not used, there was a tendency that the depth of the groove became deeper toward the end of the masking M, and the distribution of the groove depth varied depending on the position.

In the present embodiment, the meaning that the shielding member 40 is attached and fixed to the separator substrate B so that the separator substrate B and the shielding member 40 can be moved synchronously is as follows.
This is closely related to the fact that electrolytic processing is performed while transporting the separator base material B along the electrode nozzle 30. That is, even if a member having an electric field shielding effect is provided on the electrode nozzle 30 side, the masking 34 shown in FIGS.
There is no other way but to extend in the direction along the transport direction of the separator base material B, such as 35, to face the upper and lower parts of the non-masking part N of the processed surface of the separator base material. That is, providing the shielding material extending in the direction (vertical direction) orthogonal to the transport direction of the separator base material B on the electrode nozzle 30 side would hinder electrolytic processing while transporting in the horizontal direction. is there. Therefore,
Electric field shielding at the front side and the rear side in the transport direction relative to the non-masking portion N of the processed surface depends only on the front side 40a and the rear side 40b of the shielding member 40 fixed to the separator base material B. As described above, the fact that the opposing surface 32 of the electrode nozzle 30 is a continuous exposed surface extending along the transport direction of the separator base material B means the presence of the frame-shaped shielding member 40 that moves synchronously with the separator base material B. It is assumed.

(Effects) According to the present embodiment, the following effects can be obtained. -Electrode nozzle 30 as processing electrode and separator substrate B
The shielding material 40 is disposed between the
The surface to be processed of the separator base material B exposed from the opening 41 and the electrode nozzle opposing surface 32 directly facing the same are constructed in an opposing relationship in which the same shape and the same area are formed. As a result, between the opposing surfaces, A parallel electric field is formed in which all lines of electric force are parallel. Therefore, the situation where the lines of electric force are concentrated on the peripheral portion and the end portion of the surface to be subjected to the electrolytic processing is avoided, and the excessive processing of the peripheral portion and the end portion can be prevented or mitigated. The accuracy of the groove processing can be improved. With regard to fuel cell separators, there is a tendency for demands for thinner walls to increase more and more, and the improvement of the groove machining accuracy according to the present method greatly contributes to the realization of further thinner fuel cell separators.

As described above, since there is no fear of excessive processing at the peripheral portion and the end portion of the work, the distance between the electrode nozzle 30 (negative electrode) and the surface to be processed (positive electrode) of the separator base material B should be minimized. By setting a small value, the electric resistance between the two electrodes can be reduced. This reduces energy loss in electrolytic processing, improves processing efficiency and shortens processing time.

Heat generation on the separator substrate B as a work is reduced by reducing the electric resistance between the positive and negative electrodes, and thermal deformation (warpage) of the separator substrate B during electrolytic processing can be prevented. Temporarily sparger boxes 14, 15
If the separator base material B is thermally deformed during the transfer, the warped base material will hit the electrode nozzle 30 and cannot be transferred. In this regard, according to this embodiment, the possibility that the separator base material B is thermally deformed is extremely small, and there is no need to worry about the above-described accident.

At the time of electrolytic etching, since the electrolytic solution is jetted and supplied to the respective surfaces of the separator substrate B with the mask in a direction perpendicular to the surface, the electrolytic solution immediately spreads all over the surface to be processed, and the It is effectively used for electrochemical reactions such as ion elution. That is, the necessary and sufficient amount and concentration of the electrolyte are always supplied to the surface to be processed. Therefore, the fuel cell separator can be efficiently manufactured at low cost without lowering the processing accuracy of the flow path integrated type separator.

Even if an electrolytic product is generated in the gap region between the surface to be processed and the electrode nozzle 30 during the electrolytic etching, the electrolytic product is flushed with the electrolytic solution into the recovery tank 12 by the force of the injection. Therefore, an electrolytic product that reduces the efficiency of electrolytic etching does not stay near the surface to be processed, and the distance between the electrode nozzle 30 and the surface to be processed can be set small.

The separator integrated with the flow channel manufactured by using the present method has the following features or advantages as a final product. Compared with the press-formed product, the distortion is extremely small and the depth of the concave portion is uniform. For this reason, the gas flow characteristics when assembled as a battery cell and the measures for preventing the dew condensation phenomenon of water vapor in the gas flow path are easily made as intended by the designer, and the battery performance is improved. In addition, since there is almost no distortion, even when a large number of battery cells are stacked, a decrease in sealing performance due to accumulation of distortion does not occur. Furthermore, since the separator can apply an equal surface pressure to the electrode sandwiching the proton-permeable solid polymer membrane in the battery cell, local damage to the electrode can be avoided beforehand, and the battery performance can be improved. Can be improved.

(Modification) The above embodiment may be modified as follows. In the above embodiment, the shielding member 40 is adhered and fixed on the surface to be processed of the separator substrate B. However, as long as the separator substrate B and the shielding member 40 can move synchronously in the transport direction, the separator substrate B It is not necessary to fix (integrally) the shielding member 40 to the first. For example, by suspending each shielding member 40 on the work holder 22, the separator base material B and the shielding member 40 may be moved synchronously. Further, as long as the frame-shaped shielding member 40 is used, the masking 34, 35 in each electrode nozzle 30 may be omitted.

In the above embodiment, the separator base material B is held upright in the vertical direction. However, the separator base material B may be laid horizontally and held. In this case, the direction of injection and supply of the electrolyte is vertical. Further, in the above embodiment, the separator base material B is conveyed only in one direction, but the work holder 22 is periodically reciprocated during the electrolytic processing to move the separator base material B between the pair of electrode nozzles 30 back and forth. You may make them come and go.

In the above embodiment, the separator substrate B
As shown in FIG. 2, the masking M is applied only to a part of one surface (worked surface), and the entire surface is applied to the other surface (non-processed surface). Then, in the same manner as in the above-described embodiment, by simultaneously injecting the electrolytic solution from both sides onto both surfaces of the separator substrate B, the masking M
Electrolytic machining may be performed only on the surface (worked surface) on which.

In this specification, “electrolytic processing” means
This means electrolytic processing in a broad sense including electrolytic etching processing, and does not mean only electrolytic processing in a narrow sense.

The points of the present method other than those described in each claim are listed below. (A) In the method for manufacturing a fuel cell separator according to any one of claims 1 to 5, an electrolyte is injected and supplied from the direction substantially perpendicular to a surface to be processed of the separator substrate as the processing electrode. Use a surface-facing type electrode / nozzle that is possible.

(B) In the method of manufacturing a fuel cell separator according to claim 5, the separator substrate has a flat plate shape and both surfaces thereof are surfaces to be processed. Simultaneous injection and supply of electrolyte from each direction substantially perpendicular to the processing surface. More preferably, the separator base material is held in a substantially vertical direction, and an electrolytic solution is jetted and supplied from a substantially horizontal direction to a work surface extending in the vertical direction.

[0058]

As described in detail above, according to the present invention, the use of the shielding material reduces the lines of electric force caused by the difference in shape or area between the processing electrode and the surface to be processed of the separator substrate. Since it is possible to form a parallel electric field between the opposing surfaces by blocking the wraparound, it is possible to improve the accuracy of the electrolytic processing on the surface to be processed. In addition, according to the present invention, the distance between the processing electrode and the separator substrate can be set as small as possible, and the electrolytic processing efficiency can be improved, and the heat generation in the separator substrate is suppressed. It is possible to avoid thermal deformation of the separator substrate.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an outline of an apparatus for manufacturing a fuel cell separator.

FIG. 2 is a perspective view showing a part of a separator base material, a shielding material, and a manufacturing apparatus.

FIG. 3 is a plan view schematically showing a transfer system of a work holder.

FIG. 4 is a front view showing an outline of a facing surface of an electrode nozzle.

FIG. 5 is a front view showing a relationship between a separator base material and an electrode nozzle during transportation.

FIG. 6 is a cross-sectional view showing a relationship between a separator base material and an electrode nozzle during transportation.

FIG. 7 is a plan view showing an example of a fuel cell separator as a final product.

FIG. 8 is a graph showing a relationship between a measurement point and a groove depth in a prototype test.

FIG. 9 is a cross-sectional view showing an outline of a method of selecting a measurement point in a prototype test.

FIGS. 10A and 10B are a front view and a side view showing a state of generation of lines of electric force between two electrodes.

FIGS. 11A and 11B are a front view and a side view showing a state of generation of lines of electric force between two electrodes. FIGS.

FIG. 12 is a front view and a side view for explaining an idea of the present invention.

[Explanation of symbols]

30 ... electrode combined nozzle (working electrode), 32 ... facing surface, 4
0: shielding material, 53: groove pattern (recess for gas flow path configuration), B: separator substrate, M: masking on separator substrate, N: non-masking portion.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masanori Matsukawa 1st Tenno, Takaokashinmachi, Toyota City, Aichi Prefecture Aisin Takaoka Co., Ltd. (72) Inventor Yohei Kuwahara 1st, Takaokashinmachi, Toyota City, Aichi Prefecture Aisin Takaoka Corporation (72) Inventor Kenji Izumi 1658-1, Shimomachi-cho, Oita-Asahi City, Aichi Prefecture Nippon Chemical Electronics Co., Ltd. (72) Inventor Shinji Idebu 1658-1, Shimoi-cho, Owariasahi City, Aichi Prefecture Japan F term in Chemical Electronics Co., Ltd. (reference) 3C059 AA02 AB01 HA01 HA03 5H026 BB00 CC03 CX04 EE02 HH02

Claims (5)

[Claims] 1. A method of manufacturing a fuel cell separator having an integrated gas flow path, wherein a processing surface of a conductive separator base material having a shape or an area different from that of the processing electrode is spaced apart from the processing electrode by a predetermined distance. And forming a parallel electric field between the opposing surfaces by blocking the wraparound of lines of electric force resulting from the difference in shape or area between the processing electrode and the surface to be processed of the separator base material. Shielding material,
A step of arranging between the processing electrode and the separator substrate; and supplying power to both the separator substrate and the processing electrode in a state where an electrolytic solution is interposed between the facing surfaces of the processing electrode, whereby the surface to be processed of the separator substrate is processed. Further comprising the step of electrolytically processing the gas flow passage forming recess. 2. The method for manufacturing a fuel cell separator according to claim 1, wherein said shielding member is made of an electrically insulating material. 3. The processing electrode and the separator base are arranged so that the processing surface of the separator base material and the opposing surface of the processing electrode have the same shape and the same area. 2. The device according to claim 1, wherein the material is interposed between the material and the material.
Or the method for producing a fuel cell separator according to item 2. 4. The method according to claim 1, wherein the electrolytic processing of the surface of the separator substrate is performed while the separator substrate and the shielding member are synchronously moved along the processing electrode. A method for producing the fuel cell separator according to any one of the preceding claims. 5. A process for masking a part of the surface of the separator substrate, and spraying an electrolyte from the masked surface of the separator substrate in a direction substantially perpendicular to the surface of the separator substrate. An electrolytic solution is supplied and interposed between the processing surface and the processing electrode, and a non-masking portion of the processing surface is electrolyzed to form a gas flow path forming concave portion. 5. The method for producing a fuel cell separator according to any one of items 4 to 5.