WO2009096309A1

WO2009096309A1 - Press-working method for sheet metal, die therefor, and formed product

Info

Publication number: WO2009096309A1
Application number: PCT/JP2009/050969
Authority: WO
Inventors: Haruo Okahara; Masayuki Yano; Nobuyuki Kajihara; Shingo Kino; Kenji Higashi
Original assignee: Kasatani Corp.; Public University Corporation Osaka Prefecture University
Priority date: 2008-01-31
Filing date: 2009-01-22
Publication date: 2009-08-06
Also published as: JPWO2009096309A1

Abstract

A press-working method for a metal plate material uses a die having an upper die and a lower die which have pressing surfaces the outlines of which are determined so that surface irregularities composed of protrusions caused by concentration of a fluid material during press-working and of depressions caused by spreading of the fluid material during the press-working are formed on each of the front and rear sides of the blank. The press-working method heats those contact sections of the dies which make contact with the blank and simultaneously forms the surface irregularities on both sides of the plate material such that the depressions of the irregularities on one side do not correspond to the protrusions of the irregularities on the opposite side. The method can produce in a short time a metal formed product having the surface irregularities on the front and rear sides of the product with the irregularities on each side not corresponding to each other.

Description

Sheet metal pressing method, mold and molded product thereof

The present invention relates to a metal mold for sheet metal press working of a metal plate material, a press working method using the metal mold, and a molded product. Specifically, the molded product relates to a fuel cell separator.

Sheet metal pressing generally obtains a desired shape by bending or drawing a plate-shaped blank with a mold. Accordingly, the thickness of the blank is slight due to these deformations, and the molded product has a shape in which a concave portion is present on the surface opposite to the convex portion. In particular, magnesium or a magnesium alloy has poor ductility, so that such general sheet metal press processing has been performed. That is, sheet metal pressing has not been applied to the manufacture of an article made of magnesium or a magnesium alloy in which concave and convex shapes that do not correspond to the concave portion are formed on the opposite surface of the convex portion on both surfaces of the plate material.

For example, a separator for a fuel cell is provided for partitioning a large number of units composed of a fuel electrode, an air electrode, a current collector layer, and the like and supplying a reaction gas. It has a shape with a groove. To the separator, fuel gas (generally hydrogen) and oxygen (generally air) are supplied and discharged separately on the front and back sides. Are often orthogonal. In other words, since the concave and convex portions are formed on the front and back surfaces of the separator on the surface opposite to the convex portion for the groove shape, the conventional sheet metal pressing has not been applied.

A processing method for obtaining such an uneven shape that does not correspond to front and back using magnesium or a magnesium alloy is described in Patent Document 1, for example. This method is for preheating a magnesium alloy to forge a molded product with bosses and ribs. An example of forging a molded product with a thickness of 0.6 to 3.2 mm using an ingot with a thickness of 10 mm is as follows. It is shown.

The method described in Patent Document 2 relates to the manufacture of a fuel cell separator. In this method, an annealed magnesium alloy is used, and superplastic forging is slowly performed at a strain rate of 2 × 10 ⁻⁵ to 1 × 10 ⁻¹ / sec using a heated mold. Processing to a 2 mm product is illustrated.

The methods described in these patent documents are forging processes that are distinguished from sheet metal pressing, and require the preheating and annealing of the blank, and have the disadvantages that the pressing speed is slow and a lot of time is required for forming. As a result, the obtained molded product has a high manufacturing cost and must be expensive.
Japanese Patent Laid-Open No. 2001-26835 JP 2003-331858 A

The present invention eliminates the disadvantages of the above-described prior art, and enables the production of a metal molded product having an uneven shape that does not correspond to the front and back surfaces in a short time, a pressing method, and a low manufacturing cost. An object of the present invention is to provide a molded article having the above shape (specifically, a fuel cell separator).

Means and effects for solving the problems

(1) In order to achieve the above object, the present invention is a sheet metal press working method of a metal sheet material, wherein a concave and convex shape composed of convex portions due to concentration of fluid material during pressing and concave portions due to discrete is formed on the front and back surfaces of the blank. Using a mold having an upper mold and a lower mold whose contour of the pressing surface is determined, the contact portion of the mold with the blank is heated to a temperature that increases the plastic deformability of the blank, and the convex The present invention provides a sheet metal pressing method characterized by simultaneously forming unevenness having a shape that does not correspond to a concave portion on a surface opposite to a portion on both surfaces of the plate material.

According to the above method, uneven shapes having different shapes can be simultaneously formed on both surfaces of the plate blank by warm sheet metal pressing. In particular, by using a plate-like material as a blank, it is possible to obtain a material flow that reaches the final shape even if the press speed is increased, and compared with warm forging that forms from a bulk material to a plate-like material, the press time is reduced. It can be greatly shortened.

(2) In order to achieve the above object, the present invention is a mold used for warm sheet metal pressing of a metal plate material, and the upper mold and the lower mold do not have unevenness corresponding to each other vertically. And a heating portion for heating the pressing surface, the pressing surface forming an uneven shape including convex portions due to concentration of fluid material during pressing and concave portions due to discrete on the front and back surfaces of the blank. Further, the present invention provides a metal mold for sheet metal press working, characterized in that the contour is determined.

According to the above mold, the upper mold and the lower mold have a pressing surface that does not have unevenness corresponding to each other vertically, and a heating portion for heating the pressing surface, and the pressing surface is Since the contours are determined so that the concave and convex shapes consisting of convex portions due to the concentration of the fluid material and the concave portions due to the discrete are formed on the front and back surfaces of the blank, both sides of the plate blank are different by warm sheet metal pressing Shape irregularities can be formed at the same time. In particular, by using a plate-like material as a blank, it is possible to obtain a material flow that reaches the final shape even if the press speed is increased, and compared with warm forging that forms from a bulk material to a plate-like material, the press time is reduced. It can be greatly shortened.

(3) The upper mold and the lower mold each have a base that moves up and down during press working, a support fixed to the base, a base end fixed to the support, and a tip contacting the blank. A plurality of pressing elements and a through-hole through which the pressing elements are passed, supported by the base portion so as to be movable up and down, a tip end side as a contact surface to the blank, and the tip end portion of the pressing element at the retracted position. And a slide portion that protrudes from the hole and accommodates the tip of the pressing member in the through hole at the forward position, and the slide portion receives a spring force toward the forward position. .

Thus, if the contact surface to the blank at the time of pressing is composed of a pressing member fixed to a support that moves up and down together with the base and a slide portion that is supported by the base so as to move up and down, the initial to the blank Since the contact is performed at the slide portion and the pressing element is then projected, the impact on the pressing element and the load of the pressing pressure are reduced. As a result, the durability of the entire mold can be improved, and wear and damage of the mold can be prevented even when a precise press shape is obtained. Moreover, since the slide part is contacting the upper and lower sides of a blank, only the area | region which a presser contacts can be processed, without changing the thickness of a blank.

(4) The pressing elements may be formed of a plate-like body and arranged in parallel with a minute interval in a state of facing each other. When a plurality of groove-shaped or bowl-shaped irregularities are press-formed, it is necessary to provide an elongated contour portion corresponding to these at the die tip, and if a high press pressure is applied thereto, the mold is likely to be worn. However, by forming the pressing element that advances and retreats from the above-described slide portion with the plate-like body as described above, the impact applied to the pressing element and the press pressure load are reduced, and the wear can be prevented.

(5) In the mold of the above (4), the surface direction of the upper mold presser and the surface direction of the lower mold presser may be arranged so as to cross each other. According to this mold, it is possible to obtain groove-shaped or bowl-shaped uneven shapes extending in directions intersecting each other on both surfaces of the plate material. If wavy irregularities with groove-like parts are formed on the back side of the bowl-shaped part on both sides of the plate material, the upper mold and the lower mold should be pressed surfaces with irregularities corresponding to each other, and deformation of the plate material Is easy to process because it only needs to undergo bending deformation without much change in thickness. However, in order to obtain a groove-like or bowl-shaped uneven shape extending in the direction intersecting with each other on the front and back surfaces, the surface direction of the upper mold presser and the surface direction of the lower mold presser are as described above. By arranging them so as to cross each other, a highly accurate uneven shape can be obtained in a short time.

(6) In the molds of the above (3) to (5), the slide parts of the upper mold and the lower mold have the same planar shape as that of the blank after molding, and one of the upper mold and the lower mold The base portion includes a guide portion formed so as to surround the slide portion in the horizontal direction and extend above and below the slide portion, and the other slide portion of the upper die and the lower die enters the surrounding space of the guide portion. The closed cavity for press working can be formed by the guide portion and the slide portions of the upper die and the lower die. Thus, when the slide part enters the enclosed space of the guide part and presses in the closed cavity, the blank is deformed so as to fill the closed cavity. Thus, it is possible to obtain a press molded product with extremely high accuracy.

(7) In order to achieve the above object, the present invention is also characterized in that a concavo-convex shape is simultaneously formed on the front and back surfaces of a plate material using any of the molds of (2) to (6) above. A sheet metal press working method is provided.

According to this method, a pressed product with excellent characteristics based on the characteristics of the molds (2) to (6) can be obtained in a short time with respect to a plate-shaped blank.

(8) In the method of (7) above, pre-pressing can be performed in advance with another mold so that the molding area of the blank in the blank is recessed shallower than the deformation height of the pressing element. In this way, by performing the pre-pressing process, the convex portion press-molded by the pressing element rises from the concave surface, so that the height of the convex portion can be accurately controlled. Therefore, for example, it is advantageous also when obtaining the height of the convex part of the same plane as the peripheral part of the molded product.

(9) In the method of (1), (7), or (8) above, when the blank is a polygon, the concave portions in plan view with respect to each side of the blank correspond to the amount of extension by pressing. Thus, it can be formed in advance and pressed. When a polygonal blank is pressed, the material flow tends to occur so that each side of the polygon is expanded outward. According to this method, since the recessed portion corresponding to the amount of extension by press working is formed in advance on each side of the blank, a press-formed product having a high planar shape can be obtained against such material flow.

(10) In the method of (1) or (7) to (9), the temperature of the contact portion with the blank in the upper mold and the lower mold is 230 to 400 ° C., and the slide section of the upper mold and the lower mold After contacting the blank, it is desirable that the press speed to the bottom dead center is 0.5 to 30 mm / second. When the temperature of the contact portion is lower than 230 ° C., the material flow during pressing cannot be sufficiently obtained, and it is difficult to obtain an accurate uneven shape. Moreover, when the temperature of the said contact part exceeds 400 degreeC, the coarsening of the crystal grain of a blank will arise and the material of a molded article will be reduced. On the other hand, if the pressing speed is higher than 30 mm / second, the material flow cannot be sufficiently obtained, and an accurate uneven shape cannot be obtained. On the other hand, if the press speed is lower than 0.5 mm / sec, there is no problem with the quality of the molded product, but it is not desirable because it causes useless processing time.

(11) The sheet metal press working method of (1) or (7) to (10) can be advantageously applied when the blank is a sheet material for a fuel cell separator. The separator for a fuel cell has a shape having a large number of grooves for gas flow on both surfaces of a central portion of a flat plate. Therefore, if the above-described sheet metal pressing method is applied to press the groove, a pressed product having excellent characteristics based on the characteristics of these methods can be obtained in a short time.

(12) According to the present invention, in order to achieve the above object, a plurality of narrow grooves for gas flow paths are juxtaposed by sheet metal pressing, and the narrow groove on one surface and the narrow groove on the other surface intersect each other. The present invention provides a fuel cell separator characterized by being arranged in a direction to be operated.

As described above, the separator for a fuel cell has a shape having a large number of gas flow grooves on both sides of the central portion of the flat plate. In particular, the narrow groove on one surface and the narrow groove on the other surface have What is arranged in the direction intersecting each other is based on shortening the press time compared to the conventional warm-forged product separator made from a bulk material by using a sheet metal stamped product in this way. High accuracy can be provided at a low price.

(13) In the fuel cell separator of (12), the sheet metal pressing may be performed by any of the methods (1) or (7) to (11). According to this method, it is possible to provide a press-processed product having excellent characteristics based on the features of the sheet metal press-processing method of (1) or (7) to (10) at a low price.

The fuel cell separator can be subjected to surface processing such as corrosion-resistant coating after the above processing, if necessary.

1 is a perspective view schematically showing a part of a fuel cell including a fuel cell separator according to an embodiment of the present invention in an exploded state. It is a front view of the separator for fuel cells shown in FIG. It is an enlarged view centering on the groove part in FIG. It is a front view of the upper mold | type and lower mold | type of the metal mold | die which concerns on one Embodiment of this invention. It is a perspective view which shows the support body, presser, and slide part of the upper mold | type and lower mold | type shown in FIG. It is a top view of the member shown in FIG. It is a longitudinal cross-sectional view which follows the VII-VII line in FIG. FIG. 7 is a vertical cross-sectional view taken along a line VIII-VIII in FIG. 6. It is a figure which shows the manufacturing process of the separator for fuel cells shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Blank 2 Recessed part 3 Recessed part 10

Fuel cell separator

11, 12 Narrow groove 14 Peripheral part 15 Side groove 100 Upper mold 200

Lower mold

110, 210

Base

113, 213

Surrounding part

120, 220

Support body

130, 230

Presser

140, 240 Slide part

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 schematically shows a part of a fuel cell including a fuel cell separator according to an embodiment of the present invention. This fuel cell separator is based on a sheet metal press working method according to the present invention and a separator manufactured using a mold for the method as described below.

The fuel cell comprises a unit comprising a fuel electrode 20 comprising a catalyst layer 21 and a porous support 22, an air electrode 30 comprising a catalyst layer 31 and a porous support 32, and an electrolyte layer 40 positioned therebetween. Many separators are stacked, and separators 10 are arranged between the units. FIG. 1 shows one unit and separators 10 on both sides thereof in an exploded state. The separator 10 includes

narrow grooves

11 and 12 that extend so as to be orthogonal to each other on the front and back surfaces. A fuel gas such as hydrogen is supplied to the narrow groove 11 on the side facing the fuel electrode 20 to the air electrode 30. Oxygen is supplied to the narrow groove 12 on the facing side by air or the like.

FIG. 2 is a front view showing one separator 10 taken out, and FIG. 3 is an enlarged view centering on the groove portion in FIG. As shown in FIG. 2, the separator is made of a rectangular magnesium alloy, and the narrow groove 12 shown in FIG. 1 is formed at the center of the separator and is surrounded by a flat peripheral portion 14. The narrow grooves 12 are formed between the flanges 13 and extend in the vertical direction, and form a group for every five grooves. The flanges 13 located between the groups are alternately extended upward and downward to reach the peripheral part 14, and the other flanges 13 form a side groove 15 with a gap between the peripheral parts 14. is doing.

A large number of narrow grooves 12 are formed in a rectangular region as a whole, and air holes 16 serving as gas passages are formed in each corner of the rectangle by through holes. A communication groove 17 reaching the side groove 15 in the immediate vicinity extends from the vent hole 16 located at the upper right and lower left in FIG. In addition, a similar narrow groove extends in a direction orthogonal to the narrow groove 12 in a corresponding portion on the back surface of the separator, and a communication groove reaching a nearby side groove from the upper left and lower right vent holes 16 in FIG. 17 'extends (indicated by broken lines in the figure). The flange portion 13 is the same height as the peripheral portion 14 on both the front and back sides, and the tip thereof is on the same plane as the peripheral portion 14.

In the fuel cell in which the separator having this groove arrangement is incorporated, the gas introduced into the vent hole 16 flows so as to undulate the numerous fine grooves 12, and is led out from the vent hole 16 at the diagonal position. For example, the air introduced from the ventilation hole 16-1 shown in FIG. 3 reaches the side groove 15-1 immediately after passing through the communication groove 17-1, and the five narrow grooves which are the first group communicating with the side groove. 12-1 flows through the lower side groove 15-2, and then flows through the next group of fine grooves 12-2 to reach the upper side groove 15-3. In this way, the air flows while undulating the narrow grooves 12, contacts the air electrode 30, is led out from the vent hole 16 located in the lower left of FIG. 2, and flows to the next unit. Similarly, for example, the fuel gas introduced from the vent hole 16 located in the lower right of FIG. 2 flows while undulating a large number of pores extending in the horizontal direction, contacts the fuel electrode 20, and is located in the upper left of FIG. It is led out from the vent hole 16 and flows to the next unit. Thus, by providing the narrow grooves in the direction perpendicular to the front and back of the separator, the two pairs of diagonally arranged vent holes 16 are divided into fuel gas and air (oxygen). Can be used.

The illustrated separator has a vertical and horizontal dimension of 100 mm and a thickness of 2 mm, and the

narrow grooves

11 and 12 and the flange 13 each have a width of 0.75 mm and a groove depth of 0.95 mm. However, these dimensions can be appropriately determined according to the dimensions of the fuel cell and the characteristics of the electrode material.

The magnesium alloy constituting the separator can be of various components used in general fuel cell separators. For example, as a main additive component to magnesium, 2.5 to 3.5 Al is added. % (% By weight, the same applies hereinafter), 0.6 to 1.4% Zn, and 0.2 to 1.0% Mn.

Next, taking the production of the fuel cell separator described above as an example, the sheet metal press working method according to the present invention and the mold therefor will be described.

FIG. 4 is a front view showing the upper mold 100 and the lower mold 200 constituting the mold. In the following description, unless otherwise specified, the upper mold components are indicated by numbers in the 100s, the lower mold components are indicated by numbers in the 200s, and the 1-digit and 2-digit portions of these numbers are indicated by the upper mold and the lower digits. The component corresponding to the mold shall be indicated. In this embodiment, the upper mold | type 100 and the lower mold | type 200 have arrange | positioned the thing with the same basic form upside down. Therefore, the description will be made mainly on the upper mold 100, and a part of the description on the lower mold 200 will be omitted.

The upper mold 100 includes a base 110 that is attached to a driving frame (not shown) and moves up and down during press working. The base 110 is fixed to the lower surface of the intermediate plate 112 having a fixed portion 111 fixed to the lower portion of the drive frame, an intermediate plate 112 fixed to the lower surface of the fixed portion, and a rectangular space in the central portion. And a go portion 113.

The support body 120 is fixed to the lower surface of the intermediate plate 112 so as to be accommodated in the space of the surrounding portion 113, and a large number of pressing elements 130 are fixed to the support body. The pressing element 130 is formed of a plate-like body extending in the vertical direction, and is arranged in parallel with a minute interval in a state of facing each other, extends downward in a comb-like shape from the support body 120, and a tip portion to the blank It is a contact part.

FIG. 5 is a perspective view showing the

support bodies

120 and 220, the

pressing elements

130 and 230, and the

slide parts

140 and 240 of the upper mold 100 and the lower mold 200. As shown in the figure, the pressing element 130 of the upper mold 100 and the pressing element 230 of the lower mold 200 each having a plate shape are arranged so that the surface directions are orthogonal to each other. The support 120 includes an inner plate 121 positioned on the upper side and an outer plate 122 positioned below the inner plate. The outer plate 122 is formed with a through hole that receives the presser 130. The presser 130 is passed through the through hole and abuts the lower surface of the inner plate 121, and a through hole provided in the same position of each presser 130 and a corresponding through hole provided in the outer plate 122. Bolts 123 are passed through and fixed to the outer plate 122. The presser 130 of the upper mold 100 and the presser 230 of the lower mold 200 are provided corresponding to the

narrow grooves

11 and 12 of the fuel cell separator shown in FIGS. 1 and 2, respectively.

A slide part 140 is mounted below the support 120 in the space of the surrounding part 113 so as to be movable up and down. The slide part 140 has a plurality of elongated through holes that allow the pressing elements 130 to pass individually, is supported by the base part 110 so as to be movable up and down, and has a distal end side as a contact surface with the blank. The slide part 140 is arranged so that the tip of the pressing element 130 protrudes from the through hole in the raised retreat position, and the tip part of the pressing element 130 is accommodated in the through hole in the lowered advance position. . The protruding amount of the pressing element 130 when the sliding part 140 is retracted is determined so that the tip of the pressing element 130 protrudes from the surface of the sliding part 140 surrounding the pressing element 130 over a length corresponding to the depth of the narrow groove of the separator. . The slide portion 140 receives a spring force toward the forward movement position, and is in the forward movement position when no press pressure is applied. In order to apply this spring force, through holes extending in the vertical direction are formed at the four corners of the outer plate 122 and the inner plate 121, and the compression coil spring 150 is inserted therein. The spring 150 abuts on the intermediate plate 112 at the upper end and abuts on the slide portion 140 at the lower end, thereby applying a spring force directed toward the forward movement position (downward) to the slide portion 140.

6 is a plan view of the member shown in FIG. 5, FIG. 7 is a longitudinal sectional view taken along line VII-VII in FIG. 6, and FIG. 8 is a stepwise longitudinal sectional view taken along line VIII-VIII in FIG. FIGS. 7A and 8A show a state where the slide portion 140 is in the forward position, and FIGS. 7B and 8B show a state where the slide portion 140 is in the backward position.

The slide portion 140 is guided by the surrounding portion 113 and is movable in the vertical direction, and is prevented from coming down downward by a bolt B160. That is, the bolt B160 has a head 161 at one end, and is provided with a threaded portion 163 at the tip via a columnar body 162. The inner plate 121 and the outer plate 122 are provided with through holes having a diameter smaller than that of the head 161 of the bolt B160 and allowing the body portion 162 to pass therethrough, and the slide portion 140 is provided with a female screw. The bolt B160 has a head 161 located in a recess 1120 provided at the lower portion of the intermediate plate 112, the body portion 162 passes through the inner plate 121 and the outer plate 122, and the screw portion 163 at the tip is a female screw of the slide portion 140. It is screwed. In this embodiment, the bolts B160 are arranged at four locations shown in FIG. 5, but the position and number of these bolts B160 are appropriately determined. In this state, the slide part 140 is pressed by the coil spring 150 and is in the advanced position, and a gap S is formed between the slide part 140 and the outer plate 122 as shown in FIGS. 7 (a) and 8 (a). When the slide part 140 takes the retracted position during pressing, the bolt B160 rises a distance corresponding to the gap S with respect to the inner plate 121 and the outer plate 122. The recess 120 of the intermediate plate 112 is formed with a depth that allows the bolt B160 to rise.

In this embodiment, the

slide parts

140 and 240 of the upper mold 100 and the lower mold 200 have the same planar shape as that of the blank after molding. The slide part 140 of the upper mold 100 is located at a position where the lower end protrudes downward from the lower surface of the surrounding part 113 in both the forward movement position and the backward movement position. On the other hand, the slide portion 240 of the lower mold 200 has an upper end portion at a position below the upper surface of the surrounding portion 213 in both the forward position and the retracted position, and as a result, exceeds the upper surface of the sliding portion 240 in the surrounding portion 213. A portion extending upward serves as a guide portion 213 a that receives the blank and the slide portion 140 of the upper mold 100. With this structure, when the upper die 100 is lowered during pressing, the lower end portion of the slide portion 140 enters the surrounding space of the guide portion 213a, and the guide portion and the upper die and the lower die slide portion close the press working. A cavity is formed.

The fixing between the members of the fixing portion 111, the intermediate plate 112, the surrounding portion 113, the inner plate 121, and the outer plate 122 is performed by through bolts B indicated by broken lines in the drawing. The intermediate plate 112 and the surrounding portion 113 are formed with a circulation path H for passing a heat medium.

The manufacture of the fuel cell separator of FIGS. 1 and 2 using this mold is performed as follows. First, a blank 1 shown in FIG. 9A is prepared. This blank is a rectangular plate material corresponding to the outer shape of the separator, and indented portions 2 having a concave shape in plan view are formed in advance on each side of the blank so as to correspond to the amount of extension by press working. Next, in order to obtain the state of FIG. 9B, primary pre-pressing is performed so that the molding region formed by the

pressers

130 and 230 is recessed shallower than the deformation height by the presser to form the recessed portion 3. . By this primary pre-press, the plate material extends in the plane direction, the recessed portion 2 is eliminated, and each side of the blank becomes linear. In order to accurately obtain this linear deformation, it is desirable that the preliminary pressing is performed with a mold having a closed cavity having a dimension after deformation.

Next, in order to form the side grooves 15 shown in FIG. 9 (c), secondary preliminary pressing is performed using a mold having pressing portions corresponding to these. And in order to obtain the state of FIG.9 (d), it press-processes using the metal mold | die shown in FIG.

This pressing is performed by placing a blank on the slide part 240 of the lower die 200 and lowering the upper die 100 (or raising the lower die 200). The upper and lower molds are close to each other, and first, the

slide portions

140 and 240 are in contact with the blank. When the mold further advances while the slide part is in contact with the blank, the

slide parts

140 and 240 resist the spring force of the coil springs 150 and 250 to the retracted positions shown in FIGS. 7 (b) and 8 (b). It moves and the plate-shaped

pressers

130 and 230 protrude from the through hole of the slide portion. Along with this, the material in contact with the pressing element is discretely deformed into a concave shape, and the material positioned between the pressing elements is pushed and concentrated between the pressing elements. As a result, the material rises between the pressing elements and fills the space surrounded by the pressing elements and the slide portion. Thus, the blank is formed with a concavo-convex shape composed of convex portions (grooves) due to concentration of material and discrete concave portions (thin grooves). As a result of the protrusion protruding up to contact with the slide portion, the height becomes the same as the area around the narrow groove forming area in the blank. At this time, since the upper and lower slide portions are stopped at a position in contact with the surrounding area, the thickness of the blank does not change. Further, along with this deformation, the material also moves from the central part to the peripheral part. However, since the space for accommodating the blank is closed by the guide part 213a, the extension to the peripheral part is limited, and the whole As a result, a molded product having an accurate dimension is obtained.

In this press working, it is desirable that the temperature of the contact portions of the

pressers

130 and 230 and the

slide portions

140 and 240 with the blank is 230 to 400 ° C. The pressing speed is preferably 0.5 to 30 mm / second after the upper and

lower slide sections

140 and 240 are in contact with the blank and before the bottom dead center. In order to obtain stability after material flow, it is desirable to hold the mold at a bottom dead center for a predetermined time, and the holding time is preferably up to 10 seconds in consideration of production efficiency. However, if sufficient stability after material flow is obtained depending on the blank material and pressing conditions, the holding at the bottom dead center can be omitted. In addition, it is desirable to apply a release agent to the mold in order to make the material flow of the blank smooth. After that, in order to form the communication groove 17 of FIG. 9E, another metal mold is pressed, and in order to obtain the state of FIG. The through holes 18 and 19 are formed to obtain the separator 10.

Thus, the fuel cell separator can be manufactured in a short time. Further, heat treatment such as blank annealing is not required in advance for manufacturing, and the manufacturing time is short in this respect as well, but heat treatment may be performed as necessary.

Examples of the present invention will be described below. First, a rectangular blank having a vertical and horizontal dimension of 100 mm and a thickness of 2 mm was formed from a AZ31 magnesium alloy plate. Next, in the blank, an arc-shaped recessed portion that was recessed 6 mm from a straight line connecting the corners at the center of the side was formed by a cutting press. In addition, a concave portion having a depth of 0.4 mm was formed in a region where a narrow groove was to be formed by a primary preliminary press, and a side groove 15 and a communication groove 17 were formed by a secondary preliminary press. And the press work was performed using the metal mold | die shown in FIG. The press device is a servo motor press having an output of 300 tons, and the

pressers

130 and 230 and the

slide portions

140 and 240 of the mold are made of SKD11. The temperature of the contact portion with the blank in these portions is as follows. The heat medium was supplied to the circulation path H so that it might become 350 degreeC. The blank was placed on the slide part 240 of the lower mold 200, the upper mold 100 was lowered, and after the slide part 140 was in contact with the blank, the lowering speed was 1.5 mm / second. And after hold | maintaining the upper mold | type 100 for 5 second in the bottom dead center which passed through the predetermined fall amount, the upper mold | type 100 was raised and the blank was taken out. In the obtained separator, the

narrow grooves

11 and 12 are accurately formed in a rectangular cross section, and the dimensional accuracy is 0.75 ± 0.02 mm in width and 0.95 ± 0.03 mm in depth, It was good.

Other Embodiments The present invention is not limited to the above embodiment, and various modifications can be made. For example, as the fuel cell separator to be manufactured, the dimensions of each part are not limited to those described above, and various shapes and dimensions can be used depending on the application. The direction in which the gas channel narrow groove extends may be perpendicular to the front and back of the separator, cross at another appropriate angle, or extend in the same direction.

When the pressing element is formed of a plate-like body and is arranged in parallel with a minute interval in a state of facing each other, as in the above embodiment, the pressing element corresponds to all the narrow grooves of the separator. In addition to forming all the narrow grooves in one press process, a single groove or multiple grooves are formed on the surface of the separator in a single press process, which is necessary for multiple press processes. It is also possible to form a small number of narrow grooves. In this case, one or a plurality of pressing elements are provided on the first press working mold, and a pressing element corresponding to the narrow groove to be formed next is added to the previous pressing element at the second and subsequent presses. Provide in the mold. By adding the next pressing member while leaving the one corresponding to the previous pressing member in the second and subsequent presses, it is possible to prevent the previously formed narrow groove from being deformed during the second and subsequent pressing operations. By forming the entire narrow groove by a plurality of press processes in this way, it is possible to reduce the load applied to the mold and the press machine at the time of each press process.

The blank does not necessarily need to be pressed in the closed space depending on the concavo-convex shape and the accuracy required for it, and in that case, the guide portion 213a can be omitted. Depending on the required shape of the article, the presser can be formed in various shapes such as a columnar shape and a block shape, and the tip of the presser corresponds to the molded product without providing a slide portion. It is good also as an uneven | corrugated shape.

The sheet metal press working method and the mold for the same according to the present invention are not limited to the production of a fuel cell separator, and can be applied to the production of various articles. For example, a cooling plate disposed between components that generate heat, such as an electronic component, has meandering grooves on the front and back surfaces and forms a coolant channel between the wall surfaces of the component. The plate-like article having such a groove is made of magnesium or a magnesium alloy, and thus has the advantages of excellent heat conduction, light weight and good electromagnetic shielding properties, and the present invention is advantageous for its production. Can be applied to.

In addition to the magnesium or magnesium alloy of this embodiment, the blank material can be aluminum or aluminum alloy of JIS 1000 to 5000, and sheet metal pressing is performed under the same processing conditions as in this embodiment. Can do. It is also possible to use blanks made of other metal materials that can be processed, such as titanium or titanium alloys.

Claims

A sheet metal press working method of a metal plate material, wherein the contour of the pressing surface is determined so as to form a concavo-convex shape consisting of convex portions due to concentration of fluid material during pressing and concave portions due to discrete on the front and back surfaces of the blank. Using a mold having an upper mold and a lower mold, the contact portion of the mold with the blank is heated to a temperature that enhances the plastic deformability of the blank, and the recesses do not correspond to the surface opposite to the protrusions. Is formed on both sides of the sheet material at the same time.
A mold used for warm sheet metal press working of a metal plate material, wherein the upper mold and the lower mold have no pressing surface corresponding to the upper and lower sides, and a heating unit for heating the pressing surface. And the pressing surface has a contour determined so as to form a concavo-convex shape composed of a convex portion due to concentration of fluid material during pressing and a concave portion due to discrete on the front and back surfaces of the blank. Die for press working.
Each of the upper mold and the lower mold includes a base that moves up and down during press processing, a support fixed to the base, a plurality of base ends fixed to the support, and a distal end serving as a contact portion with a blank. A presser and a through hole through which the presser passes, supported by the base so as to be movable up and down, the tip side is a contact surface to the blank, and the tip of the presser protrudes from the through hole in a retracted position 3. A slide portion that houses the tip of the pressing element in the through hole at the advanced position, and the slide portion receives a spring force toward the advanced position. Metal mold for sheet metal press working as described.
The metal mold for sheet metal pressing according to claim 3, wherein the pressing elements are formed of a plate-like body, and are arranged in parallel with a minute interval in a state of facing each other.
5. The metal mold for sheet metal pressing according to claim 4, wherein the surface direction of the upper die presser and the surface direction of the lower die presser are arranged so as to cross each other.
The slide part of the upper mold and the lower mold has the same planar shape as that of the blank after molding, and one base part of the upper mold and the lower mold surrounds the slide part in the horizontal direction and moves the slide part up and down. A guide part formed beyond the direction, and the other slide part of the upper mold and the lower mold enters the surrounding space of the guide part, and the guide part, the slide part of the upper mold and the lower mold, The metal mold for sheet metal pressing according to claim 3, wherein a closed cavity for pressing is formed.
3. A warm sheet metal press working method, wherein uneven shapes are simultaneously formed on the front and back surfaces of a sheet material using the mold according to claim 2.
The warm sheet metal press working method according to claim 7, wherein a pre-pressing process is performed in advance with another mold so that a molding region of the blank in the blank is recessed shallower than a deformation height by the pressing element.
The blank is a polygon in a plan view, and a concave portion in a plan view is formed in advance on each side of the blank so as to correspond to the amount of extension by the press work, and the press work is performed. The sheet metal press working method according to 1.
The temperature of the contact part with the blank in the upper mold and the lower mold is 230 to 400 ° C., and the press speed to the bottom dead center is 0.5 to 400 after the slide parts of the upper mold and the lower mold are in contact with the blank. The sheet metal press working method according to claim 1, wherein the sheet metal press working method is 30 mm / second.
The sheet metal press working method according to claim 1 or 7, wherein the blank is a sheet material for a fuel cell separator.
The sheet metal press working method according to claim 1 or 7, wherein the blank is made of magnesium, aluminum, titanium, or any alloy thereof.
A plurality of narrow grooves for gas flow paths are juxtaposed by sheet metal pressing, and the narrow groove on one surface and the narrow groove on the other surface are arranged in a direction intersecting each other. Separator.
The separator for a fuel cell according to claim 13, wherein the sheet metal press working is performed by the method according to claim 1 or 7.