Press forming method for metal plate and press apparatus

Abstract

This press forming method for a metal plate includes: a preliminary forming step for pressing protruding curved surfaces (41, 51) onto a metal plate (100) and forming bulging parts (C1, C2) having, as top portion, pressed regions (R13, R23) by the protruding curved surfaces (41, 51); and a shape forming step for pressing outer-side regions, at both sides of the pressed regions (R13, R23), of the bulging parts (C1, C2), and forming a metal plate having flattened top parts (81, 82) and a sidewall part (83) that is contiguous to the top parts (81, 82) and that has no pressing force applied thereto.

Description

METHOD AND APPARATUS FOR PRESS-FORMING METAL PLATES

[0001] The present invention relates to a method for press-forming a metal plate and a press apparatus.

[0002] Fuel cell separators generally have grooves that define gas flow paths for fuel gas and oxidant gas. One known method for forming these grooves is to press-form a metal plate using a press mold consisting of a die and a punch (see, for example, Patent Document 1).

[0003] In the forming method described in Patent Document 1, a plate material is pressed with the tip surface of a punch to form a protrusion, and then the side wall of the protrusion is sandwiched between the inclined surface of the die and the inclined surface of the punch and rolled to form a protrusion. That is, in a single press working, the protrusion is formed by bulging, and the side wall of the protrusion is rolled to form a protrusion.

[0004] Patent No. 5573511

[0005] However, in the above-mentioned forming method, the side wall of the protruding portion is further rolled, which tends to thin the side wall. As a result, cracks and deformations (waviness) tend to occur between the protruding portion and the thin side wall. This makes it difficult to control the product thickness, and it is difficult to omit thickness inspection.

[0006] A method for press-forming a metal plate according to one aspect of the present invention includes a pre-forming step in which a convex curved surface is pressed against a metal plate before forming to form a protruding portion having a peak at the pressed area by the convex curved surface, and a shape forming step in which outer areas on both sides of the pressed area in the protruding portion are pressed to flatten the peak, and after forming, the metal plate is formed with the flattened peak and side wall portions that are connected to the peak and to which no pressing force is applied.

[0007] According to the present invention, it is possible to improve the processing accuracy in press forming.

[0008] FIG. 1 is an exploded perspective view showing a schematic configuration of a power generation cell of a fuel cell. FIG. 2 is a cross-sectional view taken along line A-A in FIG. 1. FIG. 3 is a diagram showing the cross-sectional shape of a first press die used in the preforming step. FIG. 4 is a diagram showing a pressing state during the preforming step. FIG. 5 is a diagram showing another pressing state during the preforming step. FIG. 6 is a diagram showing a final pressing state in the preforming step. FIG. 7 is a diagram showing the cross-sectional shape of a second press die used in the shape forming step. FIG. 8 is a diagram showing a final pressing state in the shape forming step.

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The following description and drawings are examples for explaining the present invention, and appropriate omissions and simplifications have been made for clarity of explanation. Furthermore, in the following description, identical or similar elements and processes are given the same reference numerals, and duplicate explanations may be omitted. Note that the content described below merely shows an example of an embodiment of the present invention, and the present invention is not limited to the following embodiment, and can be implemented in various other forms.

[0010] A metal sheet press-forming method according to an embodiment of the present invention can be applied to power-generating cells of a fuel cell stack mounted on a fuel cell vehicle such as a fuel cell automobile. FIG. 1 is an exploded perspective view schematically illustrating the configuration of a single power-generating cell 10 used in the fuel cell stack. The fuel cell stack is formed by stacking a plurality of power-generating cells. Of the three orthogonal axial directions in FIG. 1 , the x-axis direction is the stacking direction of the power-generating cells. The power-generating cell 10 includes a unitized electrode assembly (UEA) 11 and a first separator 12 and a second separator 13 disposed on either side of the unitized electrode assembly 11. In FIG. 1 , arrow A1 (open arrow) indicates the flow of oxidant gas, and arrow A2 (hatched arrow) indicates the flow of fuel gas.

[0011] The first separator 12 and the second separator 13 are formed by pressing a thin metal plate. Examples of the thin metal plate include a steel plate, a stainless steel plate, an aluminum plate, a titanium plate, and any of the above metal plates that have been subjected to a corrosion-resistant surface treatment.

[0012] The integrated electrode structure 11 includes a membrane electrode assembly (MEA) 11a and a frame member 14 joined to the peripheral edge of the membrane electrode assembly 11a. The membrane electrode assembly 11a includes an electrolyte membrane 15, an anode electrode 16 provided on one side of the electrolyte membrane 15, and a cathode electrode 17 provided on the other side of the electrolyte membrane 15.

[0013] The frame member 14 is a rectangular annular frame member having a rectangular opening of substantially the same shape as the rectangular membrane electrode assembly 11a. The anode electrode 16 and the cathode electrode 17 are arranged so that their outer peripheral edges sandwich the edge of the rectangular opening of the frame member 14, and are joined to the frame member 14 with an adhesive or the like. For example, the edge of the rectangular opening of the frame member 14 is arranged so as to be sandwiched between the cathode electrode 17 and the surface of the electrolyte membrane 15 on which the cathode electrode 17 is provided, and is joined to the electrolyte membrane 15 and the cathode electrode 17.

[0014] The first separator 12 is provided with an oxidant gas outlet manifold 20a, an oxidant gas inlet manifold 20b, a fuel gas outlet manifold 22a, and a fuel gas inlet manifold 22b. The oxidant gas outlet manifold 20a and the fuel gas inlet manifold 22b are arranged side by side in the z direction at one end (negative side) of the first separator 12 in the y direction. The oxidant gas inlet manifold 20b and the fuel gas outlet manifold 22a are arranged side by side in the z direction at the other end (positive side) of the first separator 12 in the y direction.

[0015] The second separator 13 is provided with an oxidant gas outlet manifold 21 a, an oxidant gas inlet manifold 21 b, a fuel gas outlet manifold 23 a, and a fuel gas inlet manifold 23 b. The oxidant gas outlet manifold 21 a and the fuel gas inlet manifold 23 b are arranged side by side in the z direction at one end (negative side) of the second separator 13 in the y direction. The oxidant gas inlet manifold 21 b and the fuel gas outlet manifold 23 a are arranged side by side in the z direction at the other end (positive side) of the second separator 13 in the y direction.

[0016] The frame member 14 is provided with an oxygen-containing gas outlet manifold 26a, an oxygen-containing gas inlet manifold 26b, a fuel gas outlet manifold 27a, and a fuel gas inlet manifold 27b. The oxygen-containing gas outlet manifold 26a and the fuel gas inlet manifold 27b are arranged side by side in the z direction at one end (negative side) in the y direction of the frame member 14. The oxygen-containing gas inlet manifold 26b and the fuel gas outlet manifold 27a are arranged side by side in the z direction at the other end (positive side) in the y direction of the frame member 14.

[0017] The oxidant gas outlet manifold 20a and the oxidant gas inlet manifold 20b of the first separator 12 and the oxidant gas outlet manifold 21a and the oxidant gas inlet manifold 21b of the second separator 13 are arranged opposite each other, with the oxidant gas outlet manifold 26a and the oxidant gas inlet manifold 26b of the frame member 14 between them. The fuel gas outlet manifold 22a and the fuel gas inlet manifold 22b of the first separator 12 and the fuel gas outlet manifold 23a and the fuel gas inlet manifold 23b of the second separator 13 are arranged opposite each other, with the fuel gas outlet manifold 27a and the fuel gas inlet manifold 27b of the frame member 14 between them.

[0018] The first separator 12, the second separator 13, and the frame member 14 each have a coolant outlet communicating hole and a coolant inlet communicating hole formed between the communicating holes 22b, 23, and 27b and the communicating holes 20a, 21a, and 26a, and between the communicating holes 20b, 21b, and 26b and the communicating holes 22a, 23a, and 27a. The first separator 12 and the second separator 13 are each formed by joining the outer peripheral edges of a pair of thin plates by welding or the like. The coolant flows through the first separator 12 (between the pair of thin plates) and the second separator 13 in the Y direction.

[0019] A grooved surface 24 extending in the y direction is formed on the surface of the first separator 12 facing the integrated electrode structure 11. The grooved surface 24 forms a fuel gas flow path between the first separator 12 and the integrated electrode structure 11, which is connected to the fuel gas inlet manifold 22 b and the fuel gas outlet manifold 22 a.

[0020] Similarly, a grooved surface 25 extending in the y direction is formed on the surface of the second separator 13 facing the integrated electrode structure 11. The grooved surface 25 forms an oxidant gas flow path between the second separator 13 and the integrated electrode structure 11, which is connected to the oxidant gas inlet manifold 21 b and the oxidant gas outlet manifold 21 a.

[0021] Fig. 2 is a partial cross-sectional view of the power-generating cell 10 taken along line A-A in Fig. 1, and is a cross-sectional view of the concave-convex groove surfaces 24, 25 of the first separator 12 and the second separator 13. The separators 12, 13 are each formed by joining a pair of thin plates PL1, PL2, and Fig. 2 shows the thin plate PL1 on one side of the first separator 12 (the integrated electrode structure 11 side) and the thin plate PL2 on one side of the second separator 13 (the integrated electrode structure 11 side).

[0022] The grooved surfaces 24, 25 are formed by press molding. The grooved surface 24 of the first separator 12 (thin plate PL1) has a plurality of convex portions 24a and concave portions 24b extending in the y direction, which are alternately formed in the z direction. A fuel gas flow field 30 is formed between the concave portions 24b and the opposing surface of the integrated electrode structure 11. Similarly, the grooved surface 25 of the second separator 13 (thin plate PL2) has a plurality of convex portions 25a and concave portions 25b extending in the y direction, which are alternately formed in the z direction. An oxidant gas flow field 31 is formed between the concave portions 25b and the opposing surface of the integrated electrode structure 11.

[0023] 2, a cooling channel is formed by the protrusions 24a on the opposite side of the thin plate PL1 of the first separator 12 from the fuel gas channel 30, and the cooling medium flows along the cooling channel. Similarly, a cooling channel is formed by the protrusions 25a on the opposite side of the thin plate PL2 of the second separator 13 from the oxidant gas channel 31, and the cooling medium flows along the cooling channel.

[0024] The thin plates PL1 and PL2 have the same shape, and flipping the thin plate PL1 in the x-axis direction results in the thin plate PL2. The convex portions 24a and 25a and the concave portions 24b and 25b also have the same shape, and flipping the convex portions 24a and 25a in the x-axis direction results in the concave portions 24b and 25b. However, the thin plates PL1 and PL2, and the convex portions 24a and 25a and the concave portions 24b and 25b, do not have to have the same shape. The thickness of the thin metal plates PL1 and PL2 used in the first and second separators 12 and 13 is, for example, approximately 0.1 mm. The pitch (the distance in the z-direction) of the concave portions 24b and 25b is, for example, approximately 1 mm, and the height (the width in the x-direction) of the concave and convex portions is, for example, approximately 0.5 mm.

[0025] The first separator 12 and the second separator 13 are formed by press-forming a metal sheet. The press-forming method in this embodiment includes a preforming step and a shape forming step.

[0026] 3 is a diagram showing the cross-sectional shape of the first press die used in the preforming step. The first press die includes a die (hereinafter referred to as a die) 4 into which a sheet metal 100 (corresponding to sheets PL1 and PL2) serving as a workpiece is set, and a die (hereinafter referred to as a punch) 5 that moves toward the die 4 to press the sheet metal 100.

[0027] The die 4 and the punch 5 are each provided with a plurality of protrusions 40, 50 that press the metal sheet 100. The protrusions 40 of the die 4 are formed so as to protrude from a flat surface (die flat surface) 43 facing the punch 5 toward the punch 5. The protrusions 50 of the punch 5 are formed so as to protrude from a flat surface (punch flat surface) 53 facing the die 4 toward the die 4.

[0028] As described above, the convex portions 24a, 25a and the concave portions 24b, 25b of the separators 12, 13 have shapes that are inverted relative to each other in the x-axis direction ( FIG. 2 ). Therefore, the convex portions 40 of the die 4 and the convex portions 50 of the punch 5 are configured to have the same shape (symmetrical in the x-axis direction). The multiple convex portions 40 are arranged in the z-axis direction at a predetermined pitch P. Similarly, the multiple convex portions 50 are also arranged in the z-axis direction at the same pitch P as the convex portions 40. However, the convex portions 50 are arranged with a pitch offset of P / 2 relative to the convex portions 40 in the z-axis direction. The height dimension of the convex portions 40, 50 is H, and the width dimension is W.

[0029] The top of the convex portion 40 is configured as a convex curved surface 41 that is convex upward. Similarly, the top of the convex portion 50 is configured as a convex curved surface 51 that is convex downward. In the example shown in Fig. 3, the convex curved surfaces 41, 51 have a cross-sectional shape that forms an arc. As described above, the convex portions 24a, 25a and the concave portions 24b, 25b of the first and second separators 12, 13 have symmetrical shapes, and therefore the convex curved surface 41 of the convex portion 40 and the convex curved surface 51 of the convex portion 50 that form these are curved surfaces of the same shape, with only the orientation of the surfaces being different.

[0030] (Explanation of Preforming Process) Figures 4 to 6 are diagrams illustrating the preforming process. Figures 4 and 5 are diagrams illustrating the pressing state during the preforming process. Meanwhile, Figure 6 is a diagram illustrating the final pressing state of the preforming process. When the punch 5 is lowered toward the die 4 in the state shown in Figure 3, the apex (convex curved surface 51) of the convex portion 50 comes into contact with the upper surface of the thin metal sheet 100.

[0031] 4, the sheet metal 100 is press-formed so that the material is stretched mainly in region R21 where the convex curved surface 51 of the convex portion 50 of the punch 5 abuts and in region R11 where the convex curved surface 41 of the convex portion 40 of the die 4 abuts. That is, when a pressing force is applied to the portion where the convex curved surfaces 41, 51 abut, the pressing force mainly stretches the material in that portion, reducing the thickness. As a result, the portion of the sheet metal 100 where the convex portion 50 abuts is deformed downward convexly, and the portion where the convex portion 40 abuts is deformed upward convexly.

[0032] Figure 5 shows a state in which the punch 5 has been further lowered from the state shown in Figure 4. As the punch 5 is further lowered, the contact area of ​​the convex curved surfaces 41, 51 with the metal sheet 100 becomes larger than the pressing state shown in Figure 4. That is, the contact area of ​​the convex curved surfaces 41, 51 gradually expands as the punch 5 descends. Therefore, in Figure 5, the regions R12, R22 where the convex curved surface 41 of the die 4 and the convex curved surface 51 of the punch 5 contact the metal sheet 100 satisfy the relationships R12 > R11 and R22 > R21.

[0033] FIG. 6 shows the final pressing state of the preforming process, in which the punch 5 has been further lowered from the state shown in FIG. 6 . In the state shown in FIG. 6 , the descent of the punch 5 is stopped by a positioning unit (not shown) that determines the distance D between the die 4 and the punch 5. After preforming, the sheet metal 100 has a first protruding portion C1 that is upwardly convex, with the pressing region (region R13) pressed by the convex curved surface 41 of the convex portion 40 at its apex, and a second protruding portion C2 that is downwardly convex, with the pressing region (region R23) pressed by the convex curved surface 51 of the convex portion 50 at its apex. The first protruding portion C1 is the portion above the center in the height direction of the corrugated sheet metal 100 after preforming, and the second protruding portion C2 is the portion below the center in the height direction. During the preforming process, the regions R13 and R23 to which the pressing force is applied are mainly deformed, resulting in a slight reduction in the thickness of those portions.

[0034] In the example shown in Figure 6, the distance D from the flat portion 43 to the flat portion 53 is set to D = H0 so that the height of the formed product in the preforming process is the same as the target height (the height of the finished product shown in Figure 2). Therefore, no gap is generated between the flat portions 43, 53 and the top of the corrugated sheet metal 100. In this way, it is preferable to set the height dimension H (Figure 3) of the protrusions 40, 50 so that D = H0. However, for example, the height dimension may be set slightly larger, such as H0 + ΔH, so that a gap is generated between the flat portions 43, 53 and the top of the corrugated sheet metal 100.

[0035] (Configuration of the second press die) Figure 7 is a diagram showing the cross-sectional shape of the second press die used in the shape forming process. The second press die includes a die 6 on which the corrugated sheet metal 100 is set after the preforming process is completed, and a punch 7 that moves toward the die 6 to press the sheet metal 100. To distinguish between the first press die (first die) and the second press die (second die), the die 4 and punch 5 of the first press die are sometimes referred to as the first die and first punch, respectively, and the die 6 and punch 7 of the second press die are sometimes referred to as the second die and second punch, respectively.

[0036] The die 6 and the punch 7 are each provided with a plurality of protrusions 60, 70 for pressing the metal sheet 100. The protrusions 60 of the die 6 are formed so as to protrude from a flat surface 63 facing the punch 7 toward the punch 7. The protrusions 70 of the punch 7 are formed so as to protrude from a flat surface 73 facing the die 6 toward the die 6. The protrusions 60 of the die 6 and the protrusions 70 of the punch 7 are configured to have the same shape (symmetrical shapes in the x-axis direction).

[0037] The multiple protrusions 60 are arranged in the z-axis direction at the same pitch P as in the case of the die 4. The multiple protrusions 70 are also arranged in the z-axis direction at the same pitch P as the protrusions 60. Furthermore, the protrusions 70 are arranged at a pitch P / 2 offset in the z-axis direction relative to the protrusions 60. The height dimension of the protrusions 60, 70 is H, and the width dimension is W1.

[0038] The top of convex portion 60 is composed of a flat portion 61 and curved portions 62 provided on both ends of flat portion 61 in the z-axis direction. The top of convex portion 70 is composed of a flat portion 71 and curved portions 72 provided on both ends of flat portion 71 in the z-axis direction. Convex portions 60 and 70 have the same shape, and convex portion 70 is obtained by inverting convex portion 60 in the x-axis direction.

[0039] After the preforming process (FIG. 6), the corrugated sheet metal 100 is set on the die 6 as shown in FIG. 7. Region R13 in the corrugated sheet metal 100 is the region pressed by the convex portion 40 of the die 4 in the preforming process. Region R23 is the region pressed by the convex portion 50 of the punch 5 in the preforming process. In regions R13 and R23 pressed by the convex portions 40 and 50, the reduction in thickness of the sheet metal 100 due to forming is greater than in the unpressed regions.

[0040] The width dimension W1 of the convex portion 60 of the die 6 used in the shape forming process is set so that the curved surface portions 62 formed on both ends of the flat portion 61 in the z-axis direction abut against the region outside the region R13 of the metal sheet 100, i.e., the outer region (a region where the thickness reduction in the preforming process is relatively small). In other words, it is set so that W1 > W. As with the convex portion 60, the width dimension of the convex portion 70 of the punch 7 is also set to W1 (> W), and the curved surface portions 72 on both ends of the flat portion 71 in the z-axis direction abut against the region outside the region R23 of the metal sheet 100, i.e., the outer region.

[0041] 7, when the punch 7 is lowered toward the die 6, the curved surface portions 72 at both ends of the apex of the convex portion 70 come into contact with and press against the region outside region R23 of the corrugated sheet metal 100. The curved surface portions 72 of the punch 7 come into contact with the region outside region R23 on the concave side of the downwardly convex protruding portion (second protruding portion C2) having the region R23 as its apex. Similarly, the curved surface portions 62 at both ends of the apex of the convex portion 60 of the die 6 come into contact with and press against the region outside region R13 of the corrugated sheet metal 100. The curved surface portions 62 of the die 6 come into contact with the region outside region R13 on the concave side of the upwardly convex protruding portion (first protruding portion C1) having the region R13 as its apex.

[0042] When the punch 7 is further lowered, the region R23 facing the flat portion 71 of the convex portion 70, i.e., the top of the second protrusion C2, is sandwiched between the flat portion 63 and the flat portion 71 of the die 6 and flattened. As with the region R23, the first protrusion C1 of the region R13 facing the flat portion 61 of the convex portion 60 is also sandwiched between the flat portion 61 and the flat portion 73 and flattened. Finally, the punch 7 is lowered to the position shown in Figure 8, and the shape forming process is completed. The metal sheet 100 is formed into the same uneven shape as the uneven groove surfaces 24, 25 shown in Figure 2.

[0043] In the shape-forming process, the thickness of the sheet metal 100 is reduced primarily in the regions where it is pressed by the curved surfaces 62 and 72. Because the sheet metal 100 is formed into a waveform in the preforming process, the distance traveled by the punch 7 from the start of forming in FIG. 7 to the end of forming in FIG. 8 is shorter than the distance traveled by the punch 5 in the preforming process. Furthermore, because the regions pressed by the curved surfaces 62 and 72 are outside the regions R13 and R23, the reduction in thickness during the preforming process is very small. Therefore, the reduction in thickness of the regions pressed by the curved surfaces 62 and 72 throughout the entire process, including the preforming and shape-forming processes, can be minimized. Furthermore, in the regions R13 and R23 in FIG. 7 between the curved surfaces 62 and 62 or 72 and 72, the sheet metal 100 is sandwiched between the pressed regions of the curved surfaces 62 and 62 or 72 and 72, preventing the sheet metal 100 from flowing outward, resulting in very little change in the sheet metal 100's thickness.

[0044] As described above, in the shape forming process, the thickness of the metal sheet 100 is reduced mainly in the regions pressed by the curved surface portions 62, 72. Since the curved surface portions 62, 72 press the regions outside the regions R13, R23, in the shape forming process, it is possible to form the metal sheet 100 into shape while suppressing a reduction in thickness in the regions R13, R23, which have been reduced in thickness in the preforming process.

[0045] As shown in Figure 8, the finished product after the shape forming process has a top portion 81 formed to conform to the flat portion 61 and curved portion 62 (see Figure 7) of the convex portion 60 of the die 6, a top portion 82 formed to conform to the flat portion 71 and curved portion 72 (see Figure 7) of the convex portion 70 of the punch 7, and a side wall portion 83 connecting the top portions 81 and 82. The flat portions 81a and 82a of the top portions 81 and 82 are formed by flattening the curved portions of the regions R13 and R23 formed in the preforming process, and the thickness of the top portions 81 and 82 changes very little in the shape forming process. Furthermore, the R-shaped portions 81b and 82b at both ends of the top portions 81 and 82 are formed in the shape forming process.

[0046] As described above, each portion of the tops 81 and 82 of the finished product is formed in the preforming process or the shape-forming process. That is, the tops 81 and 82 are the pressing regions in the press forming of this embodiment. The thickness reduction due to forming is distributed throughout the tops 81 and 82, suppressing local thickness reduction. Furthermore, since no pressing force is applied to the side wall 83 throughout the preforming and shape-forming processes, thickness reduction of the side wall 83 can be minimized. The region where no pressing force is applied is realized by forming a gap G (see FIG. 8 ) between the protrusion 60 of the die 6 and the protrusion 70 of the punch 7 in the preforming and shape-forming processes, where no pressing force is applied to the sheet metal 100. That is, because the gap G is formed, a region (side wall 83) where no pressing force is applied is created between the spaced-apart tops 81 and 82 (the pressing regions in the press forming of this embodiment).

[0047] As described above, according to the press-forming method of this embodiment, it is possible to suppress the reduction in thickness of the side wall portion 83 and to minimize the overall reduction in thickness of the finished molded product. As a result, it is possible to improve the processing accuracy in press-forming and omit the need for thickness inspection.

[0048] It is preferable to set the size of the regions R13, R23 to which the pressing force is applied in the preforming step as large as possible in order to distribute the reduction in wall thickness. Specifically, it is preferable to set the width dimension W of the convex portions 40, 50 of the die 4 and punch 5 so that the boundaries of the regions R13, R23 shown in Figure 7 are inside and near the curved portions 62, 72 of the convex portions 60, 70.

[0049] In the above-described embodiment, the convex curved surfaces 41, 51 formed at the apexes of the convex portions 40, 50 have been described as having a cross-sectional shape that is an arc, but various other convex curved surface shapes are possible. For example, if the cross-sectional shape is a sinusoidal wave shape (the shape of the apex region of the sinusoidal wave curved surface), it is highly effective in suppressing the thickness reduction in the regions R13, R23. Therefore, the convex curved surfaces 41, 51 may have a sinusoidal wave shape.

[0050] The various embodiments and modifications described above are merely examples, and the present invention is not limited to these unless the features of the invention are impaired. Other embodiments that are conceivable within the scope of the technical idea of ​​the present invention are also included within the scope of the present invention.

[0051] 4 Die, 5 Punch, 10 Power generation cell, 11 Integrated electrode structure, 12 First separator, 13 Second separator, 24, 25 Concave and grooved surface, 24a, 25a, 40, 50, 60, 70 Convex portion, 24b, 25b Concave portion, 41, 51 Convex curved surface, 43, 53, 61, 63, 71, 73 Flat portion, 62, 72 Curved portion, 81, 82 Top portion, 81a, 82a Flat portion, 81b, 82b R-shaped portion, 83 Side wall portion, 100 Thin metal plate, C1, C2 Protruding portion, R11, R12, R13, R21, R22, R23 Region

Claims

1. a preforming step of pressing a convex curved surface against a metal plate to form a protruding portion having a peak at a region pressed by the convex curved surface; a shape forming step of pressing outer regions on both sides of the pressing region of the protruding portion to flatten the top portion, and forming a metal plate having the flattened top portion and side wall portions that are continuous with the top portion and to which no pressing force is applied, In the preforming step, the protrusion is formed so that the height of the protrusion will be a target height of the metal plate after the shape forming step.

2. The method for press-forming a metal sheet according to claim 1, In the preforming step, The convex curved surface is formed on the top of each of the first die convex portion and the first punch convex portion, pressing one surface of the metal plate with a first die protrusion to form a first protruding portion from the other surface of the metal plate; A method for press-forming a metal plate, comprising pressing the other surface of the metal plate with a first punch convex portion in a different area spaced apart from the pressing area by the first die convex portion, thereby forming a second protrusion portion in which one surface of the metal plate protrudes.

3. The method for press-forming a metal sheet according to claim 2, In the shape forming step, press molding using a second die having a second die convex portion protruding from the die flat portion and having a convex portion with a flat top surface; and a second punch having a second punch convex portion protruding from the punch flat portion and having a convex portion with a flat top surface; pressing the outer region of the concave surface of the first protrusion with both ends of the convex portion top surface of the second die convex portion while restricting the first protrusion to the target height with the punch flat portion; a die flat portion restricting the second protrusion portion to the target height, while pressing the outer region of the concave surface of the second protrusion portion with both ends of the convex portion top surface of the second punch convex portion.

4. The method for press-forming a metal sheet according to claim 2, A method for press-forming a metal plate, wherein the curved surface shapes of the convex surfaces formed on the first die convex portion and the first punch convex portion are set to the shape of the apex region of a sinusoidal curved surface.

5. The method for press-forming a metal sheet according to claim 1, The metal plate forms a separator for a fuel cell.

6. A press apparatus for performing the metal plate press forming method according to claim 1 or 2, The molding machine includes a first mold used in the preforming step and a second mold used in the shape forming step, The first mold comprises: a first die having a first die protrusion provided to protrude from a die flat portion, the protrusion top surface of which is configured by the convex curved surface; a first punch having a first punch convex portion provided to protrude from the punch flat portion and having a convex portion top surface formed by the convex curved surface, The second mold comprises: a second die having a second die protrusion provided to protrude from the die flat portion and having a flat top surface; a second punch having a second punch convex portion that is provided protruding from the punch flat portion and has a flat top surface;