JP2004139861A - Apparatus of manufacturing separator for solid polymer fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus of manufacturing a separator for a fuel cell, which can be used for a solid polymer fuel cell low in cost and high in durability, can mold the separator without cracking or rupture and with stability, and can prevent a mold roll from breaking, where working mistake or the like causes phase or pitch shift to produce the breaking. <P>SOLUTION: A flat portion is provided on the periphery, and a convex portion and a concave portion, which serve as a gas flow channel, are provided on the other area than the periphery. A set of upper and lower reduction rollers where at least a pair of convex/concave portions are provided at such position as face each other, being in front of work surfaces applied with convex/concave working similar to those of the separator. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an apparatus for manufacturing a separator used in a polymer electrolyte fuel cell used for an automobile driven by electric power, a small-scale power generation system, and the like.
[0002]
[Prior art]
With increasing awareness of environmental conservation, the transition from the current internal combustion engine using fossil fuels to electric drive type vehicles using hydrogen-based polymer electrolyte fuel cells and distributed cogeneration systems is being considered worldwide. I have. In order to make these new technologies widely available to the general public, it is necessary to promote the development of technologies related to cost reduction and high reliability, including the fuel supply system.
In recent years, the development of fuel cells for electric vehicles has begun to progress rapidly with the success of the development of solid polymer materials.
Unlike polymer electrolyte fuel cells, which are conventional alkaline fuel cells, phosphoric acid fuel cells, molten carbonate fuel cells, and solid electrolyte fuel cells, solid polymer fuel cells use a hydrogen ion selective permeation type organic membrane as the electrolyte. A fuel cell characterized by the fact that, in addition to pure hydrogen, hydrogen gas obtained by reforming alcohols is used as fuel, and power is extracted by electrochemically controlling the reaction with oxygen in the air. System. Solid polymer membranes function well even when they are thin, and since the electrolyte is fixed in the membrane, they function as electrolytes when the dew point in the battery is controlled, so fluidity such as aqueous electrolytes and molten salt electrolytes Another feature is that the battery itself can be designed to be compact and simple without the need to use a medium having a certain size.
[0003]
The polymer electrolyte fuel cell is a single cell with a sandwich structure consisting of a separator having a hydrogen flow path, a fuel electrode, a solid polymer membrane, an air (oxygen) electrode, and a separator having an air (oxygen) flow path. A stack in which the single cells are stacked is used. Therefore, both sides of the separator have independent flow paths, one side is a hydrogen path, and the other side is a flow path of air and generated water.
As a constituent material of the polymer electrolyte fuel cell that operates in a region below the boiling point of the cooling aqueous solution, the temperature is not so high, and it is possible to sufficiently exhibit corrosion resistance and durability under the environment, Furthermore, carbon-based materials have been used by machining to form an arbitrary flow path shape, such as by cutting, but stainless steel and titanium have been used to reduce costs and downsize, that is, to make separators thinner. Technological development for the application of is progressing.
[0004]
Conventionally, as stainless steels for fuel cells, Patent Document 1 (Japanese Patent Application Laid-Open No. Hei 4-247852), Patent Document 2 (Japanese Patent Application Laid-Open No. Hei 4-358844), Patent Document 3 (Japanese Patent Application Laid-Open No. Hei 7-188870), Patent As disclosed in Document 4 (JP-A-8-165546), Patent Document 5 (JP-A-8-225892), and Patent Document 6 (JP-A-8-31620), high corrosion resistance is required. There are stainless steels for fuel cells that operate in a molten carbonate environment.
Further, as disclosed in Patent Document 7 (Japanese Patent Application Laid-Open No. 6-264193), Patent Document 8 (Japanese Patent Application Laid-Open No. 6-293914), and Patent Document 9 (Japanese Patent Application Laid-Open No. 9-67672), The invention of a solid oxide fuel cell material operating at a high temperature of one hundred degrees has been made.
[0005]
Further, Patent Document 10 (Japanese Patent Application Laid-Open No. 10-228914) discloses that a stainless steel (SUS304) is stretch-formed (also referred to as press-formed) for the purpose of obtaining a fuel cell separator having low contact resistance with an electrode of a unit cell. ) To form a bulged portion formed of a large number of irregularities on the inner peripheral portion, and form a gold plating layer having a thickness of 0.01 to 0.02 μm on the bulging tip side end surface of the bulged formed portion. A fuel cell separator is disclosed, wherein the fuel cell separator is interposed between the stacked unit cells when forming the fuel cell, and the electrodes of the unit cell and the bulging molded portion are used. There is disclosed a technique in which a gold plating layer formed on an end surface of a bulging tip side is disposed so as to abut, and a reaction gas passage is defined between a fuel cell separator and an electrode. In addition, Patent Document 11 (Japanese Patent Application Laid-Open No. 5-29909) discloses a press-processed corrugated bipolar plate having a wavy shape for processing at low cost. Regarding molding using a roll, Patent Document 12 (Japanese Patent Application Laid-Open No. 2000-202532) discloses a manufacturing method in which a flat plate is sandwiched between dies and the dies are compressed by rolling rolls. When a polymer electrolyte fuel cell is actually prototyped based on these technologies, ductile cracks may occur in the bulge formed by irregularities, and the press load increases due to the formation of a repetitive shape of fine irregularities. It was difficult to form well. In view of the above, the present inventors have disclosed in Patent Document 13 (Japanese Patent Application No. 2001-112937) a feature in which a pair of upper and lower pressing rolls whose surfaces are subjected to unevenness processing similar to the shapes of the protrusions and recesses of the separator are provided. An apparatus for manufacturing a separator for a polymer electrolyte fuel cell has been disclosed. By using this processing method, it is possible to apply a low-cost, high-durability type polymer electrolyte fuel cell, perform stable forming processing without cracking or breaking, reduce the pressing load, and reduce unevenness. It is possible to manufacture a separator which is uniformly formed and has less deformation and waving of the peripheral flat portion. However, in this processing method, the phase of the upper and lower rolls and the pitch in the roll axis direction must be accurately matched, and in the mass production process, occasional work errors may occur, and the phase and pitch may shift, In addition, there is a problem that the mold is seized due to the mismatch between the upper and lower concave and convex portions, and the mold is destroyed. The mold roll is very expensive, and if the mold is destroyed, a serious problem occurs in terms of production efficiency and cost.
[0006]
Patent Document 14 (Japanese Patent Application Laid-Open No. 55-61324) discloses a manufacturing method characterized in that a steel strip to be moved in the longitudinal direction is formed by a cold roll machine, and an extruded pattern is simultaneously formed by a roll in the rolling stage. Although disclosed, a roll for forming an extruded pattern is provided on a roll stand, the upper roll thereof has a convex portion corresponding to the extruded pattern, and the lower roll has a concave portion. In the present structure, there is a possibility that a phase or a pitch shift may occur due to an operation mistake at the time of setting the roll, and when the shift occurs, the unevenness on the roll surface is destroyed due to a mismatch between the upper and lower uneven portions.
[0007]
Further, in Patent Document 15 (Japanese Patent Laid-Open No. 5-200307), in a catalyst carrier for purifying exhaust gas formed by winding a flat plate and a corrugated plate in an overlapping state, the unevenness is formed on the surface of the flat plate and the top of the corrugated plate in contact with the flat plate. A manufacturing method is disclosed in which portions are formed to face each other, and winding is performed while engaging the concave and convex portions of both plates. The forming rolls are provided with grooves in the circumferential direction and can be aligned in the roll axis direction (board width direction), but the upper and lower forming rolls are shifted in the circumferential direction or axial direction. In the case where the fuel cell separator to be processed in the present invention is processed, the phase shift in the circumferential direction or the axial direction cannot be avoided and mechanically insufficient. is there.
[0008]
[Patent Document 1] JP-A-4-247852 [Patent Document 2] JP-A-4-358844 [Patent Document 3] JP-A-7-188870 [Patent Document 4] JP-A-8-165546 [Patent] Reference 5 Japanese Patent Application Laid-Open No. 8-225892 [Patent Document 6] Japanese Patent Application Laid-Open No. 8-31620 [Patent Document 7] Japanese Patent Application Laid-Open No. 6-264193 [Patent Document 8] Japanese Patent Application Laid-Open No. 6-293940 [Patent Document 9] Japanese Patent Application Laid-Open No. 9-67672 [Patent Document 10] Japanese Patent Application Laid-Open No. 10-228914 [Patent Document 11] Japanese Patent Application Laid-Open No. 5-29909 [Patent Document 12] Japanese Patent Application Laid-Open No. 2000-202532 [Patent Document 13] Japanese Patent Application No. 2001-112937 [Patent Document 14] Japanese Patent Application Laid-Open No. 55-61324 [Patent Document 15] Japanese Patent Application Laid-Open No. 5-200307
[Problems to be solved by the invention]
In view of the above problems, the present invention can be applied to a low-cost, high-durability type polymer electrolyte fuel cell. An object of the present invention is to provide an apparatus for manufacturing a separator for a fuel cell, which can prevent a mold roll (also referred to as an upper roll or a lower roll) from being damaged due to a certain phase or pitch shift.
[0010]
[Means for Solving the Problems]
In order to solve the above-described problems, the present invention has been completed as a result of detailed studies through the principle of forming and working with mold rolls and trial production of various mold rolls. The gist of the invention is as follows. .
(1) In a manufacturing apparatus for a polymer electrolyte fuel cell separator having a flat portion in the periphery and a convex portion and a concave portion except for the peripheral portion serving as a gas flow path, the shape of the convex portion and the concave portion of the separator is similar. A separator for a polymer electrolyte fuel cell, comprising: a pair of upper and lower pressing rolls having at least one set of concave and convex portions subjected to concave and convex processing at a position in front of and opposed to the processed surface with concave and convex processing. manufacturing device.
(2) The apparatus for manufacturing a separator for a polymer electrolyte fuel cell according to (1), wherein the concave and convex portions of the pair of upper and lower pressing rolls are present outside a region where the material to be processed is passed.
(3) In a pair of upper and lower pressing rolls, a concave / convex portion in which the concave portion has a groove width in the roll circumferential direction of 1.5 to 3.0 times the width of the convex portion, and a concave portion in which the groove width in the roll axis direction is convex. The polymer electrolyte fuel cell according to (1) or (2), wherein at least one set of uneven portions having a width of 1.5 to 3.0 times the width of the portion is provided at opposing positions in the circumferential direction of the roll. Separator manufacturing equipment.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, details of the present invention will be described.
As described above, in the process of forming the separator having the repetitive cross-sectional shape of the concave and convex portions, there is a problem that the upper and lower rolls are damaged due to the seizure of the mold due to the inconsistency of the upper and lower concave and convex portions due to a phase or pitch shift caused by an operation error or the like.
The present inventors provide a dummy uneven portion in front of the upper and lower roll surfaces in the roll rotation direction, thereby protecting a portion of the upper and lower roll mold having a repeated cross-sectional shape of the uneven portion for transfer-molding the separator shape. Based on this concept, mold rolls of various shapes were prototyped, and experiments were conducted in which the mold rolls were shifted in phase and pitch. As a result, a mechanism was found that could prevent the mold rolls from being broken due to mold galling.
FIG. 1 shows an example of a sectional view of a separator manufactured by the manufacturing apparatus according to the present invention. FIG. 2 is a schematic view showing an example of constructing a polymer electrolyte fuel cell stack using the separator manufactured according to the present invention. In FIG. 3, the separator is continuously formed by rotating a pair of molding die rolls 10 and 11, whose surfaces have been subjected to irregularities, while transferring the pattern of the irregularities on the surface to the plate material. An example of a rolling roll in a manufacturing apparatus for forming a product will be described. The upper and lower molding die rolls 10 and 11 are driven synchronously, and a groove having a thickness of about the plate thickness is cut in the center of the vertical roll just before the mold rolls 10 and 11 to prevent meandering of the plate material. Provided side guide 12 is provided.
[0012]
FIG. 4 is an elevational view of the pressing roll according to the present invention, in which a concavo-convex pattern is formed at a position in front of and opposite to the separator forming surface 20 on which the concavo-convex pattern similar to the shape of the convex and concave portions of the separator has been formed. 1 shows an example of a mold roll having two sets of a concave portion 21 and a convex portion 22 which are provided with. Although FIG. 4 shows a structure having two sets of the concave part 21 and the convex part 22, at least one set is effective for avoiding breakage of the mold roll due to seizing of the mold. As shown in FIG. 5, the convex portion 22 has a spherical head shape and a concave portion, since the accuracy of mold matching is improved, and at the time of mold seizure detection, an abnormal load is uniformly applied to the pressing roll fulcrum to protect the drive bearing portion. Reference numeral 21 denotes a spherical surface, and the clearance ((width of concave portion−width of convex portion) 部 2) is preferably 0.5 to 1.5 times the plate thickness of the material to be processed. Further, it is desirable that the width of the uneven portion is equal to the minimum width dimension of the upper and lower roll mold portions having the repetitive cross-sectional shape of the uneven portion for transfer-molding the separator shape.
[0013]
FIG. 6 shows an example of a detection system that avoids galling of the separator forming surface 20 by using the concave portion 21 and the convex portion 22. The detection system includes a load cell 30 for load detection, a proximity sensor 31 and an encoder 32 for detecting a rotational position of a mold roll, and a control monitor 33 for monitoring an abnormal load and sending a stop signal to a roll drive system. . Normally, when the upper roll 10 and the lower roll 11 of the mold roll are properly aligned without any phase or pitch shift, the load becomes almost zero when the concave portion 21 and the convex portion 22 are engaged. However, when the phase and the pitch of the upper roll 10 and the lower roll 11 of the mold roll are shifted, galling occurs in the concave portion 21 and the convex portion 22, and an abnormal load is generated. A threshold value for the molding load is set in advance, and if the load value exceeds the threshold value, it is determined that the upper and lower rolls are galling due to a phase or pitch shift, and a stop signal is sent to the mold roll driving unit. The rotation of the mold roll is stopped immediately before the separator forming surface 20 is galling. Therefore, it is possible to prevent the separator molding processing surface 20 from being broken due to galling of the upper and lower surfaces. The circumferential positions of the concave portion 21 and the convex portion 22 are determined by the time from when the abnormal load is detected to when the mold roller stops and the rotational speed of the roller. That is, assuming that the time from when the abnormal load is detected to when the mold roller stops is t seconds and the roller rotation speed is N rpm, the angle between the tip of the separator molding processing surface 20 and the concave portion 21 and the convex portion 22 shown in FIG. α is 360 × N × t / 60 degrees.
The positions of the concave portions 21 and the convex portions 22 in the roll axis direction are preferably located outside the material 41 to be molded as shown in FIG. 8 in order to prevent indentation marks on the concave and convex portions from being formed on the molded product.
[0014]
As shown in FIG. 9, the concave shape is not a spherical surface, but a concave portion 21 extending in the circumferential direction of the mold roll, and two types of concave portions 21 extending in the axial direction are positioned at opposite positions in the circumferential direction of the mold roll. May be provided at least one set. The concave portion 21 and the convex portion 22 extending in the circumferential direction of the mold roll can be detected by the abnormal load when the upper and lower mold rolls are displaced in the axial direction. When the upper and lower mold rolls are displaced in the axial direction, the concave portions 21 and the convex portions 22 extending to the length can be detected. In FIG. 9, in a pair of upper and lower pressing rolls, a concave and convex portion having an extended groove width in the roll circumferential direction of the concave portion and a concave and convex portion having an extended groove width in the roll axis direction of the concave portion are provided at positions opposed to each other in the circumferential direction. Although an example having a set is described, by setting two or more sets, the operator can determine whether the upper and lower mold rolls are shifted in the circumferential direction, are shifted in the axial direction, or are shifted in both directions. It is possible to quickly and more accurately recognize whether or not a roll is present, and it is possible to easily perform roll positioning. The axial length and circumferential length of the concave portion are desirably 1.5 times or more the width of the convex portion. On the other hand, the displacement of the upper and lower mold rolls is less likely to be shifted by ピ ッ チ pitch or more (more than the width of the convex portion), and it is sufficient that the concave portion dimension is equal to the width of the convex portion before and after or right and left of the convex portion. It is preferably 3.0 times or less.
[0015]
【Example】
An uneven pattern as shown in FIG. 10 was formed by machining on a pair of forming rolls having a diameter of 250 mm and a length of 400 mm. The cross-sectional shape is as shown in FIG. 1, and the uneven portion has a width of 200 mm and a length (arc length) of 150 mm. On the other hand, the convex portion of the pressing roll for molding has a convex shape with a radius of curvature of 0.5 mm, the bottom portion is a smooth surface with a width of 0.5 mm, and the groove depth is 0.5 mm. The shape of the convex portion 22 was a spherical head surface, the radius of the spherical surface was 0.3 mm, the concave portion 21 was spherical, and the radius of the spherical surface was 0.35 mm. The convex portion 22 and the concave portion 21 were provided at a position of 50 mm from the roll end surface, and the angle α between the tip of the separator forming surface 20 and the concave portion 21 and the convex portion 22 was 60 degrees. The roll rotation speed was 9 rpm, and the time from when the excessive load was detected to when the mold roller stopped was about 1 second. The material of the mold roll was SKD11, and the workpiece was a coil of austenitic stainless steel SUS316 having a width of 250 mm and a thickness of 0.1 mm, and the stainless steel plate was continuously supplied to the separator manufacturing apparatus. After aligning the phases and axial directions of the upper and lower mold rolls, a vertical rotation of the upper and lower mold rolls is provided by a servomotor to prevent relative displacement of the upper and lower mold rolls during operation. High grade ball bearings are used. By using the above-described concave portion 21 and convex portion 22, the upper and lower mold rolls are aligned while monitoring an abnormal load using a detection system that avoids galling of the separator forming surface 20. The separator was able to be formed without destruction of the separator. The threshold value of the abnormal load was 2 kN. Thereafter, after performing appropriate surface treatments and the like, the fuel cell stack was constructed and performance tests were performed.No gas leakage or water leakage occurred, and the fuel cell was favorably used as a fuel cell using the separator according to the manufacturing method of the present invention. It was confirmed to work.
[0016]
【The invention's effect】
According to the above invention, it is possible to easily and reliably perform high-precision molding of a stainless steel separator for a polymer electrolyte fuel cell, which is extremely effective as a technique for realizing a low-cost polymer electrolyte fuel cell. Things.
[Brief description of the drawings]
FIG. 1 is an example of a cross-sectional view of a separator manufactured according to the present invention.
FIG. 2 is a schematic view showing an example of constructing a polymer electrolyte fuel cell stack using a separator manufactured according to the present invention.
FIG. 3 is a schematic view of an apparatus for manufacturing a separator using a mold roll.
FIG. 4 is an elevational view of a mold roll provided with an uneven surface in front of a separator processing surface.
FIG. 5 is a cross-sectional view of a concavo-convex portion provided circumferentially forward of a separator processing surface.
FIG. 6 is a schematic diagram of a detection system that avoids galling of a mold roll.
FIG. 7 is a side view showing a positional relationship between a separator forming surface and an uneven portion.
FIG. 8 is an elevational view of a mold roll provided with an uneven surface in front of a separator processing surface.
FIG. 9 is an elevational view of a mold roll having an uneven surface in front of a separator processing surface.
FIG. 10 is a schematic view showing an example of another mold roll surface shape in the present invention.
[Explanation of symbols]
1: separator 2: seal plate 3: electrode (carbon fiber current collector)
4: solid polymer film 10: upper mold roll (upper roll)
11: Lower mold roll (lower roll)
12: Side guide 20: Separator molding processing surface 21: Concave portion 22: Convex portion 30: Load cell 31: Proximity sensor 32: Encoder 33: Control monitor 34: Drive motor 41: Workpiece material

Claims (3)

In a polymer electrolyte fuel cell separator manufacturing apparatus having a flat portion in the periphery and a convex portion and a concave portion except for the peripheral portion serving as a gas flow path, unevenness similar to the shape of the convex portion and the concave portion of the separator is provided. An apparatus for producing a separator for a polymer electrolyte fuel cell, comprising a pair of upper and lower pressing rolls having at least one set of concave and convex portions at a position in front of and opposed to a processed surface. 2. The apparatus for manufacturing a separator for a polymer electrolyte fuel cell according to claim 1, wherein the concave and convex portions of the pair of upper and lower pressing rolls are present outside a region where the material to be processed is passed. In a pair of upper and lower pressing rolls, a concave / convex portion in which the groove width of the concave portion in the roll circumferential direction is 1.5 to 3.0 times the width of the convex portion, and a groove width in the roll axis direction of the concave portion which is the width of the convex portion. 3. The apparatus for manufacturing a separator for a polymer electrolyte fuel cell according to claim 1, wherein at least one set of concave and convex portions 1.5 to 3.0 times as large as those described above is provided at circumferentially opposed positions.

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