Method for forming metal plate, raw metal plate, and battery tray

Abstract

In a forming method for processing a metal plate and a battery tray according to the present invention, a raw metal plate (10A) has a predetermined excess length at each edge part and a predetermined corner shape at a corner part. For the raw metal plate (10A), in a portion of a first edge part (15) that lies further toward a blank corner part (17) than a straight line (L11), the blank corner part (17), and a portion of a second edge part (16) that lies further toward the blank corner part (17) than a straight line (L21), an outer shape line (163) of the raw metal plate (10A) is located outside, namely on the side opposite to a bottom surface part (110C) relative to the polygonal line comprising a line segment (P1P3) and a line segment (P3P2).

Description

Metal sheet forming method, raw metal sheet, and battery tray

[0001] The present invention relates to a metal sheet forming method, a base metal sheet, and a battery tray. Specifically, the present invention relates to a metal sheet forming method having a corner shape, such as a deep-drawn rectangular cylinder shape with a flange, a base metal sheet, and a battery tray having a corner shape. This application claims priority based on Japanese Patent Application No. 2023-162926, filed on September 26, 2023, the contents of which are incorporated herein by reference.

[0002] Batteries used in electric vehicles and the like are required to improve battery cell loading efficiency and weight reduction to extend driving range, as well as improve collision safety and reduce costs. The battery trays that store battery cells in such batteries generally have a polygonal bottom surface, such as a substantially rectangular or hexagonal shape, as shown in FIGS. 1A and 1B . Vertical walls are connected to the periphery of the bottom surface, and the ends of the vertical walls have flanges that serve as mating surfaces for the top cover. Therefore, near the vertices (corners) of the polygonal bottom surface, a corner shape is formed, as shown in FIG. 2 , consisting of vertical wall portions connected to the straight portions on both sides of the bottom corner via ridgelines, and flange portions connected to the vertical wall portions via ridgelines. To improve battery cell loading efficiency, it is desirable to design the vertical walls so that their angle with respect to the bottom surface is closer to perpendicular (straight walls) and that the radius of curvature of each ridge connecting the vertical wall, bottom surface, and flange is smaller (small R). In order to improve collision safety, it is desirable to use high-strength metal plates as the material, and in order to ensure airtightness, it is desirable to mold the body integrally without using joining methods such as welding.

[0003] As a method for integrally forming such shapes from a base metal sheet using drawing, a common press process, the methods described in Patent Documents 1 to 3 can be considered. Patent Document 1 discloses a method of preforming a corner shape so that the bottom corners protrude toward the outside of the formed product, and then forming the formed product. Patent Document 2 discloses a method of suppressing vertical wall cracks and flange wrinkles by providing notches on the edges of the flange regions on both sides of the portion that will become the vertical wall ridge of the rectangular deep-drawn shape after forming the base steel sheet. Furthermore, Patent Document 3 discloses a method of suppressing shrink flanges and improving formability by increasing the distance between the corner edges of the die hole and the edges of the blank, i.e., by forming the base metal sheet into a shape with convex corners. However, these methods require the use of materials with good formability to suppress cracks during forming, making it difficult to apply high-strength steel sheets with low formability.

[0004] Patent No. 7063429 Patent No. 7070820 Patent No. 7216937

[0005] For example, when a shape like that shown in FIG. 3 , which includes multiple corner shapes like those shown in FIG. 2 , is integrally formed from a raw metal sheet by drawing, a common press technique, using a die 1000V consisting of a punch 200V, a die 100V, and a holder 300V as shown in FIG. 4 , the periphery of the raw metal sheet is pressed against the die 100V by the holder 300V, and the central portion of the raw metal sheet is pressed from the holder 300V side of the raw metal sheet toward the die 100V by the punch 200V to perform press forming. During this forming process, the outer periphery of the raw metal sheet sandwiched between the die 100V and the holder 300V flows toward the center, forming the corner shapes and vertical walls. During this process, material flows inward during the press forming process, as shown in FIG. 5A . The flow of material near the corners of the raw metal sheet 10V at this time is schematically shown in FIG. 5B . Points a and b on the base metal sheet 10V before press forming, indicated by dotted line 410V in FIG. 5B, move to points a' and b', respectively, on the formed shape indicated by solid line 411V due to the material inflow. Considering the length a'-b' along the circumferential direction (perpendicular to the inflow direction) of the curved flange portion 143V of the corner portion 144 at the center line of the corner portion 144 and the length a-b along the circumferential direction on the base metal sheet 10V before press forming, the length a'-b' is shorter. In other words, during drawing, the curved flange portion 143V of the corner portion 144 is compressed in the circumferential direction by forming. This phenomenon is commonly referred to as a shrinkage flange, and this shrinkage flange increases the resistance to material inflow, suppressing material inflow. As a result, cracks are more likely to occur near the vertices (corners) of the polygonal bottom surface portion 110V and at the corner vertical wall ridges, and wrinkles are more likely to occur in the curved flange portion 143V of the corner portion 144. Increasing the pressure of the holder can reduce the occurrence of wrinkles, but the resistance to the flow of material increases, making cracks more noticeable.

[0006] In Patent Document 1, preforming can disperse the concentration of deformation at the shoulder, which is effective in suppressing cracking at corners. However, even if the deformation is dispersed, strain still occurs beyond a certain level, so there is a limit to the crack suppression effect, and a certain level of formability is required from the material. In Patent Document 2, forming notches in the base steel sheet reduces shrinkage flange, thereby reducing material inflow resistance and effectively suppressing cracking. However, shrinkage flange cannot be completely suppressed, so a certain level of material inflow resistance remains. Therefore, there is a limit to the crack suppression effect, and a certain level of formability is required from the material. Furthermore, Patent Document 3 discloses a method of suppressing shrinkage flange and improving formability by forming a base metal sheet with convex portions at the corners during drawing. Even with this method, shrinkage flange cannot be completely suppressed, and a certain level of material inflow resistance remains. Therefore, there is a limit to the crack suppression effect, and a certain level of formability is required from the material. All of the methods disclosed in Patent Documents 1 to 3 have a limit to the formability improvement effect. In Patent Documents 1-3, a certain level of formability is required for the material to be molded into a shape including a corner shape in which the vertical wall height is high, the vertical wall rises at an angle close to perpendicular to the bottom surface (straight wall), and the ridge lines connecting the vertical wall, bottom surface, and flange have a small radius of curvature (small R). Therefore, in any of the methods disclosed in Patent Documents 1-3, it is difficult to apply materials with low formability. On the other hand, since the formability of metal sheets generally decreases as their strength increases, molding high-strength materials is difficult. For example, in the case of steel sheets, there is a problem in that it is difficult to suppress cracking and wrinkling with steel sheets with a tensile strength of 390 MPa or more.

[0007] The inventors have conducted extensive research into the drawing of shapes including corner shapes and have discovered the following. For example, Fig. 6A schematically shows the case where forming is performed on a rectangular raw metal sheet 10V. Fig. 6A (a) shows the state before press forming, and Fig. 6A (b) shows the state after press forming. The solid line 410V1 shown in Fig. 6A (a) is the outline of the raw metal sheet 10V1 before press forming, and the solid line 411V1 shown in Fig. 6A (b) is the outline of the raw metal sheet 10V1 after press forming. Points a1 and b1 on the raw metal sheet 10V1 before press forming move to points a1' and b1', respectively, on the shape of the raw metal sheet 10V1 after press forming due to the inflow of material. When rectangular metal sheet 10V1 is press-formed, as shown in Figure 6A, the material of corner portion 144V1 shrinks in the circumferential direction of curved flange portion 143V1 (perpendicular to the inflow direction) at the center line of corner portion 144V1 during press-forming, creating a shrinkage flange, which increases the resistance to the inflow of material. This impedes the inflow of material.

[0008] Figure 6B schematically illustrates a case where a blank metal plate 10V2 is formed in which the shape of the blank metal plate is not rectangular as in Patent Document 3, but rather a blank protrusion 13V2 (hatched portion) is provided at a corner portion 144V2 of the blank metal plate 10V2, protruding outward from the rectangular blank shape. The blank protrusion 13V2 shown in Figure 6B is a portion extending outward from the solid line 410V1 of the blank metal plate 10V1 at the corner portion 144V1 of the rectangular blank metal plate 10V1 shown in Figure 6A. Figure 6B (a) illustrates the blank metal plate 10V2 before press-forming, and Figure 6B (b) illustrates the blank metal plate 10V2 after press-forming. The solid line 410V2 in Figure 6B (a) is the outline of the blank metal plate 10V2 before press-forming, and the solid line 411V2 in Figure 6B (b) is the outline of the blank metal plate 10V2 after press-forming. Points a2 and b2 on the blank metal sheet 10V2 before press forming move to points a2' and b2', respectively, on the shape of the blank metal sheet 10V2 after press forming due to the inflow of material. At this time, the outline of the blank protrusion 13V2 before press forming, shown in (a) of FIG. 6B, becomes the outline of 13V2' as shown in (b) of FIG. 6B. The imaginary unfolded shape 162 and end 162E in FIGS. 6A and 6B will be described later. When the blank protrusion 13V2 is provided at the corner portion 144V2 of the blank metal sheet 10V2, as shown in FIG. 6B, a shrink flange is suppressed. This is because, as shown in FIG. 7, the protruding portion (portion j) is not compressed in the circumferential direction (inward) and therefore does not shrink easily. As a result, the material (portion k) inside the blank protrusion 13V2 attempts to shrink due to compression inward, but because portion j is connected to portion k, portion j suppresses the compression of portion k. However, if the only protruding part is the curved flange portion 143V2 as shown in Figure 6B, the material does not shrink circumferentially at the curved flange portion 143V2, so the flange portions (F portions) on both sides of the curved flange portion 143V2 are compressed, and the flow of material is hindered at these portions.

[0009] Figure 6C schematically illustrates the forming of the blank protrusion 13V3 when it extends to a portion of the linear flanges on both sides. Figure 6C (a) shows the blank before press-forming, and (b) shows the blank after press-forming. The solid line 410V3 in Figure 6C (a) is the outline of the blank metal sheet 10V3 before press-forming, and the solid line 411V3 in Figure 6C (b) is the outline of the blank metal sheet 10V3 after press-forming. Points a3 and b3 on the blank metal sheet 10V3 before press-forming move to points a3' and b3', respectively, on the shape of the blank metal sheet 10V3 after press-forming due to the inflow of material. At this time, the outline of the blank protrusion 13V3 before press-forming shown in Figure 6C (a) becomes the outline of 13V3' shown in Figure 6C (b). As shown in Fig. 6C, by expanding the blank protrusion 13V3 of the base metal plate 10V3 to a portion of the linear flange portions on both sides thereof, it was found that the compression of the flange portions (portions F) on both sides of the curved flange portion 143V3 is alleviated, and material flow at the corner portion 144V3 is improved. Note that the blank protrusion 13V3 shown in Fig. 6C is the portion that extends outward from the solid line 410V1 of the base metal plate 10V1 at the corner portion 144V1 of the rectangular base metal plate 10V1 shown in Fig. 6A.

[0010] Furthermore, as shown in Figure 8A, by providing a draw bead on the die and holder of the mold at a position corresponding to the center of the straight flange portion where the vertical wall of the raw metal sheet is connected at the installation position of the raw metal sheet, indicated by the dotted line, and increasing the inflow resistance of the straight flange portion and reducing the inflow amount, compression of the flange portions (portions F) on both sides of the curved flange portion is alleviated. Note that Figure 8A shows the position of the draw bead 165 on the holder 300, but a paired draw bead 165 is also provided in the die 100 at the same position. As a result, it was found that while the inflow of the straight flange portion is somewhat suppressed, the inflow of material at the corners, which can lead to cracking, is further improved. However, as shown in Figure 8B, if the draw bead 1650 provided on the holder 300V is too long, it will conversely inhibit the inflow of the flange portions (portions F) on both sides of the curved flange portion, so the draw bead 1650 must be set so that it does not extend to the F portion.

[0011] Furthermore, the effect of the protrusion in suppressing shrinkage flange formation is greater the closer it is to the protruding portion (portion j) in the material flow direction, and decreases as the distance increases. Figure 9B schematically illustrates the case where a raw metal sheet 10A is formed in which the portion other than the protruding portion at the corner of the raw metal sheet is too large for the formed shape. Figure 9A illustrates the material flow into the raw metal sheet 10A according to an embodiment of the present disclosure, as described below, and Figure 9B illustrates the material flow into the raw metal sheet 10V4 when the outer shape of the raw metal sheet 10A is larger than that of Figure 9A. The dotted line 410 in Figure 9A is the outer outline of the raw metal sheet 10A before press forming, and the solid line 411 is the outer outline of the raw metal sheet 10A after press forming. Points a and b on the raw metal sheet 10A move to points a' and b', respectively, on the shape of the raw metal sheet 10A after press forming due to the material flow. At the center line of the corner portion 144, when considering the length between a-b before forming and the length between a'-b' after forming along the circumferential direction (perpendicular to the inflow direction) of the curved flange portion 143 of the corner portion 144, although it is slightly shortened and compressed, the protruding corner portion 144 suppresses compression, making the amount of compression smaller than when there is no protrusion as shown in Figure 5B, and suppressing the shrinkage of the flange. In Figure 9B, the dotted line 410V is the outline of the raw metal sheet 10V4 before press forming, and the solid line 411V is the outline of the raw metal sheet 10V4 after press forming. Points a and b on the raw metal sheet 10V4 move to points a' and b', respectively, on the shape of the raw metal sheet 10V4 after press forming due to the inflow of material. 9B , considering the length between a-b before forming and the length between a'-b' after forming along the circumferential direction (perpendicular to the inflow direction) of curved flange portion 143V of corner portion 144V, points a and b are farther apart in the inflow direction than the protruding portion (portion j), so the effect of suppressing compression of the protruding portion is smaller than in the case of FIG. 9A , the amount of compression is larger, shrinkage flange is not suppressed, and material inflow resistance increases. Therefore, if the portion other than the protruding portion of the corner portion of raw metal sheet 10V4 is made smaller than a certain size, the effect of suppressing shrinkage flange is not reduced and material inflow is improved.

[0012] The present disclosure has been made in consideration of the above, and has an object to provide a metal plate forming method, a raw metal plate, and a battery tray for integrally forming, using a high-strength metal plate, a shape including a corner shape consisting of a bottom surface portion with corners such as a battery tray, vertical wall portions connected via ridge lines to the straight portions on both sides of the corners of the bottom surface, vertical wall ridge lines connected to each ridge line, and flange portions connected to the vertical wall portions and the vertical wall ridge lines via ridge lines, wherein the vertical walls are high in height, the vertical walls rise at an angle nearly perpendicular to the bottom surface, and the ridge lines connecting the vertical walls, bottom surface, and flanges have a small radius of curvature.

[0013] (1) A method for forming a metal plate according to one aspect of the present disclosure includes: a bottom surface portion having a shape including, as part of an outline, a first straight line, a second straight line, and a first curved line connecting the first straight line and the second straight line; a first ridge line connected to the bottom surface portion by the first straight line; a second ridge line connected to the bottom surface portion by the second straight line; a first curved ridge line connected to the bottom surface portion by the first curved line and connecting the first ridge line and the second ridge line; a first vertical wall connecting the first ridge line to the opposite side of the bottom surface portion and rising; a second vertical wall connecting the second ridge line to the opposite side of the bottom surface portion and rising; a vertical wall ridge line connecting the first curved ridge line to the opposite side of the bottom surface portion and connecting the first vertical wall to the second vertical wall; a third ridge line connecting the first vertical wall to the opposite side of the first ridge line; and a fourth ridge line connecting the second vertical wall to the opposite side of the second ridge line. a second curved ridge line connecting the vertical wall ridge line on the opposite side to the first curved ridge line and connecting the third ridge line and the fourth ridge line; a first flange portion connecting the third ridge line on the opposite side to the first vertical wall and extending substantially horizontally; a second flange portion connecting the fourth ridge line on the opposite side to the second vertical wall and extending substantially horizontally; and a curved flange portion connecting the second curved ridge line on the opposite side to the vertical wall ridge line, extending substantially horizontally and connecting the first flange portion and the second flange portion, wherein the corner shape is defined as a bottom portion outer length at each position on the outline line of the bottom portion consisting of the first straight line, the second straight line, and the first curved line, when a cross section of the corner shape is viewed on a plane perpendicular to the outline line of the bottom portion, the cross-sectional length from the outline line of the bottom portion to an end of a product on the cross section is defined as a bottom portion outer length at each position on the outline line of the bottom portion, A virtual developed shape is a shape obtained by extending the bottom surface portion at each position on the outline of the bottom surface portion in a direction parallel to the bottom surface portion and perpendicular to the outline of the bottom surface portion by the outer length of the bottom surface portion at each position on the outline of the bottom surface portion, a portion of the outline of the virtual developed shape that extends from the first straight line of the bottom surface portion is a third straight line, a portion of the outline of the virtual developed shape that extends from the first curved line of the bottom surface portion is a second curved line, and a portion of the outline of the virtual developed shape that extends from the second straight line of the bottom surface portion is a fourth straight line,The shape of the portion of the material metal plate including the corner shape, when viewed in cross section on a plane perpendicular to the outline of the bottom surface portion at each position on the outline of the bottom surface portion, is the same as the imaginary developed shape or is a shape that is parallel to the bottom surface portion and extends further than the imaginary developed shape in a direction perpendicular to the outline of the bottom surface portion, the length extended from the outline of the imaginary developed shape to the outline of the material metal plate at each cross-sectional position is defined as an excess pad length α, further defined as point b1 where the first straight line and the first curved line join, and point b2 where the second straight line and the first curved line join, a line that passes through point b1 and is parallel to the bottom surface portion and perpendicular to the first straight line is defined as a first normal line L1, a line that passes through point b2 and is parallel to the bottom surface portion and perpendicular to the second straight line is defined as a second normal line L2, and the intersection of the first normal line L1 and the second normal line L2 is defined as point O, a first side of the base metal plate other than the bottom surface and a side thereof not including the second curved line with respect to the first normal line L1, a second side of the base metal plate other than the bottom surface and a side thereof not including the second curved line with respect to the second normal line L2, a blank corner of the base metal plate other than the bottom surface and between the first normal line L1 and the second normal line L2, and a corner shape height h of the corner shape is a distance from the bottom surface to the curved flange portion in a direction perpendicular to the bottom surface of the corner shape, When the pad length α is viewed along the first straight line in the direction opposite to the blank corner portion from the first normal line L1 at the first side portion of the raw metal plate, if the position on the outline of the raw metal plate where the pad length α first takes a minimum value is within 3 h from the first normal line L1, the position on the outline of the raw metal plate where the pad length α first takes a minimum value from the first normal line L1 is defined as the pad rise position of the first side portion, and if the pad length α does not take a minimum value within 3 h from the first normal line L1, the position on the outline of the raw metal plate where the pad length α first takes a smallest value within the range of 3 h from the first normal line L1 is defined as the pad rise position of the first side portion, the distance from the first normal line L1 to the pad rise position of the first side portion is defined as C1, and the pad length at that position is defined as α1,When the pad length α is viewed along the second straight line in the direction opposite to the blank corner portion from the second normal line L2 at the second side portion of the raw metal plate, if the position on the outline of the raw metal plate where the pad length α first takes a minimum value is within 3 h from the second normal line L2, the position on the outline of the raw metal plate where the pad length α first takes a minimum value from the second normal line L2 is defined as the pad rise position of the second side portion, and if the pad length α does not take a minimum value within 3 h from the second normal line L2, the position on the outline of the raw metal plate where the pad length α first takes a minimum value within 3 h from the second normal line L2 is defined as the pad rise position of the second side portion, the distance from the second normal line L2 to the pad rise position of the second side portion is defined as C2, and the pad length at that position is defined as α2, When an intersection point P1 is defined as the point of intersection between a straight line L11, which is shifted in parallel by a length C1 from the first normal line L1 toward the first side portion, and the outline of the raw metal plate, an intersection point P2 is defined as the point of intersection between a straight line L21, which is shifted in parallel by a length C2 from the second normal line L2 toward the second side portion, and the outline of the raw metal plate, and an intersection point P3 is defined as the point of intersection between a straight line that passes through the intersection point P1 and is parallel to the first straight line and a straight line that passes through the intersection point P2 and is parallel to the second straight line, then, in a portion of the first side portion closer to the blank corner portion than the straight line L11 and in a portion of the second side portion closer to the blank corner portion than the straight line L21, the outline of the raw metal plate is on the opposite side to the bottom surface portion, i.e., on the outside, of a broken line formed by line segments P1P3 and P3P2, Furthermore, when intersections Q1 and Q2 are defined as the points of intersection between a line that passes through intersection P3 and is perpendicular to the straight line connecting intersection O and intersection P3 and the outline of the raw metal plate, and when the length of line segment Q1Q2 is length B and the length of line segment P1P2 is length D, the following conditions are satisfied: 0<α1≦h (Formula 1) 0<α2≦h (Formula 2) and further the following condition is satisfied: 0.3D≦B (Formula 3) (2) In the aspect described in (1) above, the forming method includes a press forming step and a trimming step, and when the distance from line segment Q1Q2 to the furthest point on the outline of the raw metal plate between intersections Q1 and Q2 is C,On the opposite side of the blank corner portion with respect to the first normal line L1 of the first side portion and on the opposite side of the blank corner portion with respect to the second normal line L2 of the second side portion, the following may be satisfied: 0<α<3h (Formula 4), and further, 0.3D≦B≦1.5D (Formula 5) and 0≦C≦2B (Formula 6). (3) A material metal plate according to one aspect of the present disclosure includes: a bottom surface portion having a shape including, as part of its outline, a first straight line, a second straight line, and a first curved line connecting the first straight line and the second straight line; a first ridge line connected to the bottom surface portion by the first straight line; a second ridge line connected to the bottom surface portion by the second straight line; a first curved ridge line connected to the bottom surface portion by the first curved line and connecting the first ridge line and the second ridge line; a first vertical wall connecting the first ridge line to the opposite side of the bottom surface portion and rising; a second vertical wall connecting the second ridge line to the opposite side of the bottom surface portion and rising; a vertical wall ridge line connecting the first curved ridge line to the opposite side of the bottom surface portion and connecting the first vertical wall to the second vertical wall; a third ridge line connecting the first vertical wall to the opposite side of the first ridge line; and a fourth ridge line connecting the second vertical wall to the opposite side of the second ridge line. a first flange portion connected to the third ridge line on the opposite side of the first vertical wall and extending substantially horizontally; a second flange portion connected to the fourth ridge line on the opposite side of the second vertical wall and extending substantially horizontally; and a curved flange portion connected to the second curved ridge line on the opposite side of the vertical wall and extending substantially horizontally, and connecting the first flange portion and the second flange portion, wherein the corner shape is formed into a shape including a corner shape consisting of: a second curved ridge line connecting the vertical wall ridge line on the opposite side of the first curved ridge line and the first curved ridge line; a first flange portion connected to the third ridge line on the opposite side of the first vertical wall and extending substantially horizontally; and a curved flange portion connected to the second curved ridge line on the opposite side of the vertical wall ridge line and extending substantially horizontally and connecting the first flange portion and the second flange portion, wherein the corner shape is formed at each position on the outline line of the bottom portion consisting of the first straight line, the second straight line, and the first curved line, and when a cross section of the corner shape is viewed on a plane perpendicular to the outline line of the bottom portion, the cross-sectional length from the outline line of the bottom portion to an end of a product on the cross section is defined as the bottom portion outer length at each position of the outline line of the bottom portion, a virtual developed shape is a shape obtained by extending the bottom surface portion at each position on the outline of the bottom surface portion in a direction parallel to the bottom surface portion and perpendicular to the outline of the bottom surface portion by the outer length of the bottom surface portion at each position on the outline of the bottom surface portion;Among the outline lines of the imaginary developed shape, a portion extending from the first straight line of the bottom surface portion is defined as a third straight line; among the outline lines of the imaginary developed shape, a portion extending from the first curved line of the bottom surface portion is defined as a second curved line; and among the outline lines of the imaginary developed shape, a portion extending from the second straight line of the bottom surface portion is defined as a fourth straight line; when viewed in cross section on a plane perpendicular to the outline line of the bottom surface portion at each position on the outline line of the bottom surface portion, the shape of the portion of the material metal plate formed into the corner shape is the same as the imaginary developed shape or a shape that is parallel to the bottom surface portion and extends further than the imaginary developed shape in a direction perpendicular to the outline line of the bottom surface portion; the length extended from the outline line of the imaginary developed shape to the outline line of the material metal plate at each cross-sectional position is defined as an excess pad length α; furthermore, the joint between the first straight line and the first curved line is defined as point b1, and the joint between the second straight line and the first curved line is defined as point b2; a first normal line L1 is a line that passes through point b1, is parallel to the bottom surface portion, and is perpendicular to the first straight line; a second normal line L2 is a line that passes through point b2, is parallel to the bottom surface portion, and is perpendicular to the second straight line; an intersection of the first normal line L1 and the second normal line L2 is point O; a first side is a portion of the raw metal plate other than the bottom surface portion that does not include the second curved line with respect to the first normal line L1; a second side is a portion of the raw metal plate other than the bottom surface portion that does not include the second curved line with respect to the second normal line L2; a blank corner is a portion of the raw metal plate other than the bottom surface portion between the first normal line L1 and the second normal line L2; and a corner shape height h is a distance from the bottom surface portion to the curved flange portion in a direction perpendicular to the bottom surface portion of the corner shape.When the pad length α is viewed along the first straight line in the direction opposite to the blank corner portion from the first normal line L1 at the first side portion of the raw metal plate, if the position on the outline of the raw metal plate where the pad length α first takes a minimum value is within 3 h from the first normal line L1, the position on the outline of the raw metal plate where the pad length α first takes a minimum value from the first normal line L1 is defined as the pad rise position of the first side portion, and if the pad length α does not take a minimum value within 3 h from the first normal line L1, the position on the outline of the raw metal plate where the pad length α first takes a smallest value within the range of 3 h from the first normal line L1 is defined as the pad rise position of the first side portion, the distance from the first normal line L1 to the pad rise position of the first side portion is defined as C1, and the pad length at that position is defined as α1, When the pad length α is viewed along the second straight line in the direction opposite to the blank corner portion from the second normal line L2 at the second side portion of the raw metal plate, if the position on the outline of the raw metal plate where the pad length α first takes a minimum value is within 3 h from the second normal line L2, the position on the outline of the raw metal plate where the pad length α first takes a minimum value from the second normal line L2 is defined as the pad rise position of the second side portion, and if the pad length α does not take a minimum value within 3 h from the second normal line L2, the position on the outline of the raw metal plate where the pad length α first takes a minimum value within 3 h from the second normal line L2 is defined as the pad rise position of the second side portion, the distance from the second normal line L2 to the pad rise position of the second side portion is defined as C2, and the pad length at that position is defined as α2, When an intersection point between a straight line L11, which is shifted in parallel by a length C1 from the first normal line L1 toward the first side portion, and the outline of the raw metal plate is defined as an intersection point P1, an intersection point between a straight line L21, which is shifted in parallel by a length C2 from the second normal line L2 toward the second side portion, and the outline of the raw metal plate is defined as an intersection point P2, and an intersection point between a straight line that passes through the intersection point P1 and is parallel to the first straight line and a straight line that passes through the intersection point P2 and is parallel to the second straight line is defined as an intersection point P3,In the portion of the first side portion closer to the blank corner portion than the straight line L11 and in the portion of the blank corner portion and the second side portion closer to the blank corner portion than the straight line L21, the outline of the material metal plate is on the opposite side to the bottom surface portion, i.e., on the outside, of the broken line consisting of line segment P1P3 and line segment P3P2; further, when the intersections of a line that passes through intersection P3 and is perpendicular to the line connecting intersection point O and intersection point P3 and the outline of the material metal plate are defined as intersection points Q1 and Q2, and the length of line segment Q1Q2 is defined as length B and the length of line segment P1P2 is defined as length D, the following conditions are satisfied: 0<α1≦h (Equation 1) 0<α2≦h (Equation 2) and further, 0.3D≦B (Equation 3) is satisfied. (4) In the aspect described in (3) above, when the distance from the line segment Q1Q2 to the farthest point on the outline of the base metal plate between the intersection points Q1 and Q2 is defined as C, the following may be satisfied on the opposite side of the blank corner portion with respect to the first normal line L1 of the first side portion and the opposite side of the blank corner portion with respect to the second normal line L2 of the second side portion: 0<α<3h (Formula 4), and further 0.3D≦B≦1.5D (Formula 5) and 0≦C≦2B (Formula 6). (5) In the aspect described in (1) or (2) above, a bottom surface portion having a shape including, as part of its outline, a first straight line, a second straight line, and a first curved line connecting the first straight line and the second straight line; a first ridge line connected to the bottom surface portion by the first straight line; a second ridge line connected to the bottom surface portion by the second straight line; a first curved ridge line connected to the bottom surface portion by the first curved line and connecting the first ridge line and the second ridge line; a first vertical wall connecting the first ridge line to the opposite side of the bottom surface portion and rising; a second vertical wall connecting the second ridge line to the opposite side of the bottom surface portion and rising; a vertical wall ridge line connecting the first curved ridge line to the opposite side of the bottom surface portion and rising and connecting the first vertical wall to the second vertical wall; a third ridge line connecting the first vertical wall to the opposite side of the first ridge line; and a fourth ridge line connecting the second vertical wall to the opposite side of the second ridge line. a second curved ridge line connecting the vertical wall ridge line and the first curved ridge line on the opposite side and connecting the third ridge line and the fourth ridge line; a first flange portion connecting the third ridge line and the first vertical wall on the opposite side and extending substantially horizontally;a second flange portion connected to the fourth ridge line on the opposite side of the second vertical wall and extending substantially horizontally; and a curved flange portion connected to the second curved ridge line on the opposite side of the vertical wall ridge line and extending substantially horizontally, connecting the first flange portion and the second flange portion, wherein, when the corner shape is viewed in cross section on a plane perpendicular to the outline of the bottom portion at each position on the outline of the bottom portion consisting of the first straight line, the second straight line, and the first curved line, a cross-sectional length from the outline of the bottom portion on the cross section to an end of a product is defined as a bottom outer length at each position on the outline of the bottom portion, and a virtual developed shape is defined as a shape obtained by extending the bottom portion at each position on the outline of the bottom portion in a direction parallel to the bottom portion and perpendicular to the outline of the bottom portion by the bottom outer length at each position on the outline of the bottom portion, Among the outline lines of the imaginary developed shape, a portion extending from the first straight line of the bottom surface portion is defined as a third straight line; among the outline lines of the imaginary developed shape, a portion extending from the first curved line of the bottom surface portion is defined as a second curved line; and among the outline lines of the imaginary developed shape, a portion extending from the second straight line of the bottom surface portion is defined as a fourth straight line; when viewed in cross section on a plane perpendicular to the outline line of the bottom surface portion at each position on the outline line of the bottom surface portion, the shape of the portion of the material metal plate formed into the corner shape is the same as the imaginary developed shape or a shape that is parallel to the bottom surface portion and extends further than the imaginary developed shape in a direction perpendicular to the outline line of the bottom surface portion; the length extended from the outline line of the imaginary developed shape to the outline line of the material metal plate at each cross-sectional position is defined as an excess pad length α; furthermore, the joint between the first straight line and the first curved line is defined as point b1, and the joint between the second straight line and the first curved line is defined as point b2; A line that passes through the point b1, is parallel to the bottom surface portion, and is perpendicular to the first straight line is defined as a first normal line L1, a line that passes through the point b2, is parallel to the bottom surface portion, and is perpendicular to the second straight line is defined as a second normal line L2, and the intersection of the first normal line L1 and the second normal line L2 is defined as point O,a first side of the base metal plate other than the bottom surface and a side thereof not including the second curved line with respect to the first normal line L1, a second side of the base metal plate other than the bottom surface and a side thereof not including the second curved line with respect to the second normal line L2, a blank corner of the base metal plate other than the bottom surface and between the first normal line L1 and the second normal line L2, and a corner shape height h of the corner shape is a distance from the bottom surface to the curved flange portion in a direction perpendicular to the bottom surface of the corner shape, When the pad length α is viewed along the first straight line in the direction opposite to the blank corner portion from the first normal line L1 at the first side portion of the raw metal plate, if the position on the outline of the raw metal plate where the pad length α first takes a minimum value is within 3 h from the first normal line L1, the position on the outline of the raw metal plate where the pad length α first takes a minimum value from the first normal line L1 is defined as the pad rise position of the first side portion, and if the pad length α does not take a minimum value within 3 h from the first normal line L1, the position on the outline of the raw metal plate where the pad length α first takes a smallest value within the range of 3 h from the first normal line L1 is defined as the pad rise position of the first side portion, and the distance from the first normal line L1 to the pad rise position of the first side portion is defined as C1, When the pad length α is viewed along the second straight line from the second normal line L2 in the direction opposite to the blank corner portion at the second side portion of the raw metal plate, if the position on the outline of the raw metal plate where the pad length α first takes a minimum value is within 3 h from the second normal line L2, the position on the outline of the raw metal plate where the pad length α first takes a minimum value from the second normal line L2 is defined as the pad rise position of the second side portion, if the pad length α does not take a minimum value within 3 h from the second normal line L2, the position on the outline of the raw metal plate where the pad length α first takes a minimum value within 3 h from the second normal line L2 is defined as the pad rise position of the second side portion, the distance from the second normal line L2 to the pad rise position of the second side portion is defined as C2, and the pad length at that position is defined as α2, and a straight line shifted in parallel from the first normal line L1 on the metal plate toward the first side portion by a distance 0.5 times the length C1 is defined as a straight line L12A straight line L22 is a line shifted parallel to the second normal line L2 toward the second side portion by a distance 0.5 times the length C2 on the metal plate, and a draw bead is provided at a position corresponding to one or both of a range of the first side portion opposite the blank corner portion from the straight line L12 and a range of the second side portion opposite the blank corner portion from the straight line L22, but no draw bead may be provided at a position corresponding to the first side portion, the second side portion, and the die and holder corresponding to the blank corner portion between the straight line L12 and the straight line L22. (6) In the aspect described in (1) or (2) above, the base metal plate may be a steel plate having a tensile strength of 390 MPa or more. (7) In the aspect described in (3) or (4) above, the base metal plate may be a steel plate having a tensile strength of 390 MPa or more. (8) A battery tray according to one aspect of the present disclosure is a battery tray having a corner shape, the corner shape including a base metal plate made of a steel plate having a tensile strength of 390 MPa or more, the bottom surface portion having a shape including, as part of its outline, a first straight line, a second straight line, and a first curved line connecting the first straight line and the second straight line, a first ridge line connected to the bottom surface portion by the first straight line, a second ridge line connected to the bottom surface portion by the second straight line, a first curved ridge line connected to the bottom surface portion by the first curved line and connecting the first ridge line and the second ridge line, a first vertical wall connecting and rising from the opposite side of the bottom surface portion to the first ridge line, a second vertical wall connecting and rising from the opposite side of the bottom surface portion to the second ridge line, a vertical wall ridge line connecting and rising from the opposite side of the bottom surface portion to the first curved ridge line and connecting the first vertical wall and the second vertical wall, and a third ridge line connecting the first vertical wall to the opposite side of the first ridge line. a fourth ridge line connecting the second vertical wall to the second ridge line on the opposite side; a second curved ridge line connecting the vertical wall ridge line to the first curved ridge line on the opposite side and connecting the third ridge line to the fourth ridge line; a first flange portion connecting the third ridge line to the first vertical wall on the opposite side; a second flange portion connecting the fourth ridge line to the second vertical wall on the opposite side; and a curved flange portion connecting the second curved ridge line to the vertical wall ridge line on the opposite side and connecting the first flange portion to the second flange portion,When a distance from the bottom surface portion of the corner shape to the curved flange portion in a direction perpendicular to the bottom surface portion is defined as a corner shape height h, a radius of curvature of the vertical wall ridgeline is defined as Rb, an angle formed between the bottom surface portion and the first vertical wall is defined as E1, and an angle formed between the bottom surface portion and the second vertical wall is defined as E2, the following relations are satisfied: 1≦h / Rb≦15 (Formula 7) 90°≦E1<105° (Formula 8) 90°≦E2<105° (Formula 9) The corner shape is formed by press working from a single metal plate and does not include a joint between metal plates, and when a thickness of the metal plate is defined as t, a radius of curvature of the first ridgeline is r1, a radius of curvature of the second ridgeline is r2, a radius of curvature of the third ridgeline is r3, and a radius of curvature of the fourth ridgeline is r4, the following relations are satisfied: 2.5t≦r1≦0.2h (Formula 10) 2.5t≦r2≦0.2h (Formula 11) 2.5t≦r3≦0.2h (Formula 12) 2.5t≦r4≦0.2h (Formula 13) are satisfied.

[0014] According to the present disclosure, a high-strength metal plate is integrally molded into a shape including a corner shape, which includes a bottom surface portion having corners, vertical wall portions connected via ridge lines to the linear portions on both sides of the corners of the bottom surface, vertical-wall ridgelines connected to the ridgelines, and flange portions connected to the vertical wall portions and the vertical-wall ridgelines via the ridge lines. This makes it possible to provide a metal plate molding method, a raw metal plate, and a battery tray that are high in strength, have high vertical wall heights, the vertical walls rise at an angle nearly perpendicular to the bottom surface, the ridgelines connecting the vertical walls, the bottom surface, and the flanges have small radii of curvature, and do not include any joints formed by welding, adhesive, or the like.

[0015] 5A . FIG. 5B is a perspective view showing an example of a general battery tray shape. FIG. 5C is a perspective view showing an example of a general battery tray shape. FIG. 5D is a perspective view showing an enlarged view of a corner of a battery tray. FIG. 5E is a perspective view showing an example of a battery tray including a plurality of corners of the battery tray shown in FIG. 2. FIG. 5F is a schematic perspective view showing an example of a die apparatus. FIG. 5G is a schematic view showing the flow of material from a raw metal plate. FIG. 5H is a schematic view showing the flow of material near a corner of the raw metal plate of FIG. 5A . FIG. 5G is a schematic view showing the flow of material from a raw metal plate, illustrating a partial corner portion. FIG. 5H is a schematic view showing the flow of material from a raw metal plate, illustrating a partial corner portion. FIG. 5I is a schematic view showing the flow of material from a raw metal plate, illustrating a partial corner portion. FIG. 5I is a schematic view showing the flow of material from a raw metal plate, illustrating a partial corner portion. 15 is a schematic perspective view of a metal plate used in a metal plate forming method according to an embodiment of the present disclosure, before forming (a), after press forming (b), and after trimming (c). FIG. 16 is a schematic perspective view for explaining an example of a die apparatus used in a metal plate forming method according to an embodiment of the present disclosure. FIG. 17 is a schematic perspective view for explaining an example of a die apparatus used in a metal plate forming method according to an embodiment of the present disclosure. FIG. 18 is a schematic perspective view for explaining an example of a die apparatus used in a metal plate forming method according to an embodiment of the present disclosure. FIG. 19 is a schematic perspective view for explaining an example of a die apparatus used in a metal plate forming method according to an embodiment of the present disclosure. FIG. 19 is a schematic perspective view for explaining an example of a die apparatus used in a metal plate forming method according to an embodiment of the present disclosure. FIG. 19 is a schematic perspective view for explaining an example of a die apparatus used in a metal plate forming method according to an embodiment of the present disclosure. FIG. 19 is a schematic perspective view for explaining an example of a die apparatus used in a metal plate forming method according to an embodiment of the present disclosure. FIG. 19 is a schematic plan view for explaining a material metal plate according to an embodiment of the present disclosure.1 is a schematic plan view for explaining a material metal plate of an embodiment; FIG. 2 is a schematic plan view for explaining a material metal plate of an embodiment; FIG. 3 is a schematic plan view for explaining a material metal plate of an embodiment; FIG. 4 is a schematic perspective view for explaining an example of a die device used in a method for forming a metal plate of an embodiment; FIG. 5 is a schematic top view of a holder for explaining an embodiment of a die device provided with a draw bead; FIG. 6 is a schematic top view of a holder for explaining an embodiment of a die device provided with a draw bead; FIG. 7 is a schematic perspective view showing a final product of an embodiment; FIG. 8 is a schematic perspective view showing a final product of an embodiment; FIG. 9 is a schematic perspective view showing a final product of an embodiment;

[0016] Hereinafter, embodiments of the present disclosure will be described using examples, but it is clear that the present disclosure is not limited to the examples described below. In the following description, specific numerical values ​​and materials may be used as examples, but other numerical values ​​and materials may be used as long as the effects of the present disclosure are obtained. Furthermore, the components of the following embodiments can be combined with each other.

[0017] [First Embodiment] (Metal Plate Forming Method) A metal plate forming method according to this embodiment will be described with reference to FIGS. 10 to 15B . The metal plate 10 according to this embodiment is a base metal plate 10A as shown in FIG. 10( a). The base metal plate 10A is press-formed to form a metal plate 10B having a shape as shown in FIG. 10( b). The press-formed metal plate 10B is trimmed to form a final product metal plate 10C as shown in FIG. 10( c). In the embodiment described below, the metal plate 10C is a battery tray. As described above, the metal plate forming method according to this embodiment includes a step of press-forming the base metal plate 10A and a step of trimming the press-formed metal plate 10B.

[0018] In the method for forming the metal plate 10 according to this embodiment, a raw metal plate 10A is processed (by cutting (shearing), laser cutting, or the like) into the shape shown in Fig. 13, and then a mold 1000W consisting of a punch 200W, a die 100W, and a holder 300W shown in Fig. 11 is used. With the holder 300W pressing the periphery of the raw metal plate 10A against the die 100W, the punch 200W presses the central portion of the raw metal plate 10A from the holder 300W side of the raw metal plate 10A toward the die 100W, thereby performing drawing. The forming method of the metal plate 10 is a forming method in which, by performing the above-mentioned drawing, the metal plate 10 is processed into a shape including a corner shape 124 consisting of a bottom portion 110C, a first ridge line 112c, a second ridge line 113c, a first curved ridge line 152c, a first vertical wall 125c, a second vertical wall 126c, a vertical wall ridge line 121c, a third ridge line 132c, a fourth ridge line 133c, a second curved ridge line 131c, a first flange portion 141c, a second flange portion 142c, and a curved flange portion 143c, as shown in Figure 12.

[0019] Here, with regard to the corner shape 124, the bottom surface portion 110C has a shape that includes, as part of its outline, a first straight line 150c, a second straight line 151c, and a first curved line 111c that connects the first straight line 150c and the second straight line 151c.

[0020] The first ridge line 112c is connected to the bottom surface portion 110C by a first straight line 150c. The second ridge line 113c is connected to the bottom surface portion 110C by a second straight line 151c. The first curved ridge line 152c is connected to the bottom surface portion 110C by a first curved line 111c and is also connected to the first ridge line 112c and the second ridge line 113c.

[0021] The first vertical wall 125c rises up and is connected to the first ridge 112c on the opposite side of the bottom surface 110C. The second vertical wall 126c rises up and is connected to the second ridge 113c on the opposite side of the bottom surface 110C.

[0022] The vertical wall ridge line 121c is connected to the first curved ridge line 152c on the opposite side of the bottom surface portion 110C, rises, and is connected to the first vertical wall 125c and the second vertical wall 126c.

[0023] The third ridge 132c connects to the first vertical wall 125c on the side opposite to the first ridge 112c. The fourth ridge 133c connects to the second vertical wall 126c on the side opposite to the second ridge 113c.

[0024] The second curved ridge line 131c connects the vertical wall ridge line 121c on the opposite side of the first curved ridge line 152c and also connects the third ridge line 132c and the fourth ridge line 133c.

[0025] The first flange portion 141c is connected to the third ridge line 132c on the opposite side of the first vertical wall 125c and extends substantially horizontally. The second flange portion 142c is connected to the fourth ridge line 133c on the opposite side of the second vertical wall 126c and extends substantially horizontally.

[0026] The curved flange portion 143c is connected to the second curved ridge line 131c on the opposite side of the vertical wall ridge line 121c, extends approximately horizontally, and connects the first flange portion 141c and the second flange portion 142c.

[0027] As shown in Fig. 13, the portions formed at each corner of the base metal plate 10A protrude. Fig. 13 will be used to explain the details of the vicinity of the corner of the base metal plate 10A. First, the bottom surface outer length, the imaginary unfolded shape 162, the third straight line 152, the second curved line 153, and the fourth straight line 154 are defined as follows using Figs. 12 and 13.

[0028] The outer length of the bottom surface portion is the length (mm) at each position on the outline 164 of the bottom surface portion 110C, which is made up of the first straight line 150c, the second straight line 151c, and the first curved line 111c, when the cross section of the corner shape 124 is viewed on a plane perpendicular to the outline 164, from the outline 164 on the cross section to the end 162E of the final molded product.

[0029] The imaginary unfolded shape 162 is a shape in which the bottom surface portion 110C is extended at each position on the outline 164 of the bottom surface portion 110C by the outer length of the bottom surface portion at each position on the outline 164 of the bottom surface portion 110C in a direction parallel to the bottom surface portion 110C and perpendicular to the outline 164 of the bottom surface portion 110C.

[0030] The third straight line 152 is a portion of the outline of the imaginary unfolded shape 162 that extends from the first straight line 150c of the bottom surface 110C. The second curved lines 153 are portions of the outline of the imaginary unfolded shape 162 that extend vertically from each position of the first curved line 111c of the bottom surface 110C. The fourth straight line 154 is a portion of the outline of the imaginary unfolded shape 162 that extends from the second straight line 151c of the bottom surface 110C.

[0031] The shape of the portion formed into the corner shape 124 of the raw metal plate 10A, when viewed in cross section at each position on the outline 164 of the bottom surface portion 110C on a plane perpendicular to the outline 164 of the bottom surface portion 110C, is either the same as the imaginary unfolded shape 162 or a shape that is parallel to the bottom surface portion 110C and extends further than the imaginary unfolded shape 162 in a direction perpendicular to the outline 164 of the bottom surface portion 110C.

[0032] Further, the following definitions are made. The length extending from the outline of the imaginary unfolded shape 162 to the outline 163 of the material metal sheet 10A at each cross-sectional position is defined as the pad length α (mm). In other words, the pad length α is the perpendicular distance from the outline of the imaginary unfolded shape 162. The joint between the first straight line 150c and the first curved line 111c is defined as point b1. The joint between the second straight line 151c and the first curved line 111c is defined as point b2.

[0033] A line passing through point b1, parallel to the bottom surface 110C, and perpendicular to the first straight line 150c is defined as a first normal line L1. A line passing through point b2, parallel to the bottom surface 110C, and perpendicular to the second straight line 151c is defined as a second normal line L2. The intersection of the first normal line L1 and the second normal line L2 is defined as point O.

[0034] The side of the material metal plate 10A other than the bottom surface 110C and not including the second curved line 153 with respect to the first normal line L1 is defined as the first side 15. The side of the material metal plate 10A other than the bottom surface 110C and not including the second curved line 153 with respect to the second normal line L2 is defined as the second side 16. The side of the material metal plate 10A other than the bottom surface 110C and between the first normal line L1 and the second normal line L2 is defined as the blank corner 17.

[0035] As shown in FIGS. 15A and 15B, the distance from bottom surface 110C of corner shape 124 to curved flange portion 143c in a direction perpendicular to bottom surface 110C is defined as corner shape height h (mm).

[0036] As shown in FIG. 13 , in the first side portion 15 of the raw metal plate 10A, when the pad length α is observed along the first straight line 150c in the direction opposite to the blank corner portion 17 from the first normal line L1, if the position on the outline 163 of the raw metal plate 10A where the pad length α first takes a minimum value is within 3 h from the first normal line L1, then the position on the outline 163 of the raw metal plate 10A where the pad length α first takes a minimum value from the first normal line L1 is taken as the pad rise position P1 (intersection point P1) of the first side portion 15; and if the pad length α does not take a minimum value within 3 h from the first normal line L1, then the position on the outline 163 of the raw metal plate 10A where the pad length α first takes the smallest value within the range of 3 h from the first normal line L1 is taken as the pad rise position P1 of the first side portion 15. The distance from the first normal line L1 to the position P1 of the first side portion 15 where the excess material rises is defined as C1, and the excess material length at that position is defined as α1 (mm).

[0037] As shown in FIG. 13 , in the second side portion 16 of the raw metal sheet 10A, when the pad length α is observed along the second straight line 151c in the direction opposite to the blank corner portion 17 from the second normal line L2, if the position on the outline 163 of the raw metal sheet 10A where the pad length α first takes a minimum value is within 3 h from the second normal line L2, then the position on the outline 163 of the raw metal sheet 10A where the pad length α first takes a minimum value from the second normal line L2 is taken as the pad rise position P2 (intersection point P2) of the second side portion 16; and if the pad length α does not take a minimum value within 3 h from the second normal line L2, then the position on the outline 163 of the raw metal sheet 10A where the pad length α first takes the smallest value within the range of 3 h from the second normal line L2 is taken as the pad rise position P2 of the second side portion 16. The distance from the second normal line L2 to the excess pad rising position P2 of the second side portion 16 is defined as C2, and the excess pad length at that position is defined as α2 (mm).

[0038] A line L11 is a line that is translated by a length C1 from the first normal line L1 toward the first side portion 15. A line L21 is a line that is translated by a length C2 from the second normal line L2 toward the second side portion 16. An intersection point between a line that passes through intersection point P1 and is parallel to the first line 150c and a line that passes through intersection point P2 and is parallel to the second line 151c is an intersection point P3.

[0039] When defined as above, in the portion on the side of the blank corner portion 17 from the straight line L11 of the first side portion 15 and in the portion on the side of the blank corner portion 17 from the straight line L21 of the blank corner portion 17 and the second side portion 16, the outline line 163 of the material metal plate 10A is on the opposite side of the bottom surface portion 110C, i.e., on the outside, from the broken line consisting of the line segments P1P3 and P3P2.

[0040] Furthermore, when intersections Q1 and Q2 are defined as the intersections between a line that passes through intersection P3 and is perpendicular to the straight line connecting intersection O and intersection P3 and the outline 163 of the raw metal sheet 10A, and the length of line segment Q1Q2 is length B (mm), and the length of line segment P1P2 is length D (mm), the following conditions are satisfied: 0<α1≦h (Formula 1) 0<α2≦h (Formula 2) Furthermore, the following condition is satisfied: 0.3D≦B (Formula 3)

[0041] In this embodiment, the metal plate 10 is press-formed into a shape including the corner shape 124 as described above. According to this embodiment, it is possible to integrally form the metal plate 10 into a shape including the desired corner shape without using any joints such as welding or adhesive. This allows for excellent formability and suppresses wrinkles and cracks.

[0042] The distance from line segment Q1Q2 to the farthest point on outline 163 of material metal sheet 10A between intersections Q1 and Q2 is defined as C (mm). On the opposite side of blank corner portion 17 with respect to first normal line L1 of first side portion 15 and on the opposite side of blank corner portion 17 with respect to second normal line L2 of second side portion 16, the following relationship may be satisfied: 0 < α < 3h (Formula 4).

[0043] Furthermore, the following expressions may be satisfied: 0.3D≦B≦1.5D (Expression 5) and 0≦C≦2B (Expression 6).

[0044] This allows for better moldability and prevents wrinkles and cracks.

[0045] Here, the excess metal lengths α, α1, and α2 will be explained (Equation 1, Equation 2, Equation 4). Assuming that the cross-sectional length of the base metal sheet 10A does not elongate due to press forming, the outline of the imaginary unfolded shape 162 on the base metal sheet 10A becomes the end 162E of the final product. Here, the final product refers to the processed metal sheet (10C in FIG. 10C) obtained by press forming the base metal sheet 10A into the formed shape and then trimming the outer periphery. Therefore, if α, α1, and α2 are set to 0, positions P1 and P2 will be located on the outline of the imaginary unfolded shape 162, and therefore positions P1 and P2 will become the end 162E of the final product after forming. When the metal sheet (10B in FIG. 10B) that has been formed into the formed shape after press forming is trimmed to form the final product, there will be no excess metal to serve as a trimming allowance. In practice, press forming elongates the cross-sectional line length, resulting in some excess material, but this excess material is minimal in high-strength materials due to their low elongation. In actual press forming, variations in press conditions result in variations in the outer shape of the pressed product. Therefore, to obtain a product with a highly accurate outer shape, it is necessary to trim the outer periphery after press forming to create the final product. However, when trimming a high-strength base metal sheet 10A, if the excess material is small and the cross-sectional length of the cut-off portion is short, burrs are likely to occur on the sheared surface, resulting in a rough, low-quality end surface. To obtain a good, burr-free end surface, the excess material must be such that the cross-sectional length of the cut-off portion is at least a certain level. Therefore, the base metal sheet 10A must be shaped so that the excess material lengths α, α1, and α2 are greater than 0. Furthermore, the shrink flange suppression effect of the protruding portion of the base metal sheet 10A between positions P1 and P2 is greater the closer it is to the protruding portion, relative to the distance in the material flow direction, and decreases as it moves away. Therefore, if the excess pad lengths α1 and α2 are too large, the curved flange portion 143c will be farther away from the protruding portion, reducing the effect of suppressing shrinkage of the flange and making cracks more likely to occur. Therefore, it is desirable that the excess pad lengths α1 and α2 be equal to or less than the corner shape height h. Furthermore, although the size of the excess pad on the straight sides has little effect on cracks during press forming, if it is too large, a large portion will be cut off after press forming of the base metal sheet 10A.This reduces the material yield and increases the manufacturing cost, so it is desirable that the excess pad length α be equal to or less than the corner shape height h.

[0046] The relationship between the length B of the line segment Q1Q2 and the length D of the line segment P1P2 will be explained (Equation 3, Equation 5). The effect of suppressing the shrinkage flange of the protruding portion of the corner of the base metal plate 10A between position P1 and position P2 will be insufficient if the width of the protruding portion at a certain distance from the intersection point O is too small. For this reason, it is desirable that the length B be 0.3 or more relative to the length D, which is the length of the base of the protruding portion. Furthermore, if the length B is too large relative to the length D, the shape of the protruding portion will have a tip width wider than the base width, resulting in a concave shape on the side. As a result, deformation will be concentrated at the end of the side, making it more likely to crack, so it is desirable that B≦1.5D.

[0047] The distance C from the line segment Q1Q2 to the furthest point on the outline 163 of the raw metal sheet 10A between the intersections Q1 and Q2, and the length B of the line segment Q1Q2, are explained below (Equation 6). If the protruding amount of the corners of the raw metal sheet 10A is insufficient, the shrink flange suppression effect will be insufficient. Therefore, it is desirable that the outline between positions P1 and P2 of the raw metal sheet 10A is located on the opposite side of the bottom surface, i.e., outside, of the broken line formed by the line segments P1P3 and P3P2, and that C≦C. Furthermore, while a certain amount of protrusion does not significantly affect the shrink flange suppression effect, if the protruding amount is too large, a large portion of the raw metal sheet 10A will be cut off after press-forming. This reduces material yield and increases manufacturing costs, so it is desirable that C≦2B.

[0048] The base metal plate 10A may be a steel plate having a tensile strength of 390 MPa or more. The base metal plate 10A is a steel plate having a tensile strength of 390 MPa or more, and is therefore lightweight and has excellent strength.

[0049] 10 to 15B, a material metal plate according to this embodiment will be described. A material metal plate 10A according to this embodiment is a material metal plate used in forming a metal plate into a shape including a corner shape 124 including a bottom surface portion 110C, a first ridge line 112c, a second ridge line 113c, a first curved ridge line 152c, a first vertical wall 125c, a second vertical wall 126c, a vertical wall ridge line 121c, a third ridge line 132c, a fourth ridge line 133c, a second curved ridge line 131c, a first flange portion 141c, a second flange portion 142c, and a curved flange portion 143c, as shown in FIG.

[0050] The bottom surface portion 110C has a shape that includes, as part of its outline, a first straight line 150c, a second straight line 151c, and a first curved line 111c that connects the first straight line 150c and the second straight line 151c.

[0051] The first ridge line 112c is connected to the bottom surface portion 110C by a first straight line 150c. The second ridge line 113c is connected to the bottom surface portion 110C by a second straight line 151c. The first curved ridge line 152c is connected to the bottom surface portion 110C by a first curved line 111c and is also connected to the first ridge line 112c and the second ridge line 113c.

[0052] The first vertical wall 125c rises up and is connected to the first ridge 112c on the opposite side of the bottom surface 110C. The second vertical wall 126c rises up and is connected to the second ridge 113c on the opposite side of the bottom surface 110C.

[0053] The vertical wall ridge line 121c is connected to the first curved ridge line 152c on the opposite side of the bottom surface portion 110C, rises, and is connected to the first vertical wall 125c and the second vertical wall 126c.

[0054] The third ridge 132c connects to the first vertical wall 125c on the side opposite to the first ridge 112c. The fourth ridge 133c connects to the second vertical wall 126c on the side opposite to the second ridge 113c.

[0055] The second curved ridge line 131c connects the vertical wall ridge line 121c on the opposite side of the first curved ridge line 152c and also connects the third ridge line 132c and the fourth ridge line 133c.

[0056] The first flange portion 141c connects to the third ridge line 132c on the opposite side of the first vertical wall 125c and extends substantially horizontally. The second flange portion 142c connects to the fourth ridge line 133c on the opposite side of the second vertical wall 126c and extends substantially horizontally.

[0057] The curved flange portion 143c is connected to the second curved ridge line 131c on the opposite side of the vertical wall ridge line 121c, extends approximately horizontally, and connects the first flange portion 141c and the second flange portion 142c.

[0058] The outer length of the bottom surface portion is the length (mm) at each position on the outline 164 of the bottom surface portion 110C, which is made up of the first straight line 150c, the second straight line 151c, and the first curved line 111c, when the cross section of the corner shape 124 is viewed on a plane perpendicular to the outline 164 of the bottom surface portion 110C, from the outline 164 on the cross section to the end 162E of the final product.

[0059] The imaginary unfolded shape 162 is a shape in which the bottom surface portion 110C is extended at each position on the outline 164 of the bottom surface portion 110C by the outer length of the bottom surface portion at each position on the outline 164 of the bottom surface portion 110C in a direction parallel to the bottom surface portion 110C and perpendicular to the outline 164 of the bottom surface portion 110C.

[0060] The third straight line 152 is a portion of the outline of the imaginary unfolded shape 162 that extends from the first straight line 150c of the bottom surface 110C. The second curved lines 153 are portions of the outline of the imaginary unfolded shape 162 that extend vertically from each position of the first curved line 111c of the bottom surface 110C. The fourth straight line 154 is a portion of the outline of the imaginary unfolded shape 162 that extends from the second straight line 151c of the bottom surface 110C.

[0061] The shape of the portion formed into the corner shape 124 of the raw metal plate 10A, when viewed in cross section at each position on the outline 164 of the bottom surface portion 110C on a plane perpendicular to the outline 164 of the bottom surface portion 110C, is either the same as the imaginary unfolded shape 162 or a shape that is parallel to the bottom surface portion 110C and extends further than the imaginary unfolded shape 162 in a direction perpendicular to the outline 164 of the bottom surface portion 110C.

[0062] The length extending from the outline of the imaginary unfolded shape 162 to the outline 163 of the material metal sheet 10A at each cross-sectional position is defined as the pad length α (mm). In other words, the pad length α is the perpendicular distance from the outline of the imaginary unfolded shape 162. The joint between the first straight line 150c and the first curved line 111c is defined as point b1. The joint between the second straight line 151c and the first curved line 111c is defined as point b2.

[0063] A line passing through point b1, parallel to the bottom surface 110C, and perpendicular to the first straight line 150c is defined as a first normal line L1. A line passing through point b2, parallel to the bottom surface 110C, and perpendicular to the second straight line 151c is defined as a second normal line L2. The intersection of the first normal line L1 and the second normal line L2 is defined as point O.

[0064] The side of the material metal plate 10A other than the bottom surface 110C and not including the second curved line 153 with respect to the first normal line L1 is defined as the first side 15. The side of the material metal plate 10A other than the bottom surface 110C and not including the second curved line 153 with respect to the second normal line L2 is defined as the second side 16. The side of the material metal plate 10A other than the bottom surface 110C and between the first normal line L1 and the second normal line L2 is defined as the blank corner 17.

[0065] As shown in FIGS. 15A and 15B, the distance from bottom surface 110C of corner shape 124 to curved flange portion 143c in a direction perpendicular to bottom surface 110C is defined as corner shape height h (mm).

[0066] As shown in FIG. 13 , in the first side portion 15 of the raw metal sheet 10A, when the pad length α is observed along the first straight line 150c in the direction opposite to the blank corner portion 17 from the first normal line L1, if the position on the outline 163 of the raw metal sheet 10A where the pad length α first takes a minimum value is within 3 h from the first normal line L1, then the position on the outline 163 of the raw metal sheet 10A where the pad length α first takes a minimum value from the first normal line L1 is taken as the pad rise position P1 (intersection) P1 of the first side portion 15; and if the pad length α does not take a minimum value within 3 h from the first normal line L1, then the position on the outline 163 of the raw metal sheet 10A where the pad length α first takes the smallest value within the range of 3 h from the first normal line L1 is taken as the pad rise position P1 of the first side portion 15. The distance from the first normal line L1 to the position P1 of the first side portion 15 where the excess material rises is defined as C1, and the excess material length at that position is defined as α1 (mm).

[0067] As shown in FIG. 13 , in the second side portion 16 of the raw metal sheet 10A, when the pad length α is observed along the second straight line 151c in the direction opposite to the blank corner portion 17 from the second normal line L2, if the position on the outline 163 of the raw metal sheet 10A where the pad length α first takes a minimum value is within 3 h from the second normal line L2, then the position on the outline 163 of the raw metal sheet 10A where the pad length α first takes a minimum value from the second normal line L2 is taken as the pad rise position P2 (intersection point P2) of the second side portion 16; and if the pad length α does not take a minimum value within 3 h from the second normal line L2, then the position on the outline 163 of the raw metal sheet 10A where the pad length α first takes the smallest value within the range of 3 h from the second normal line L2 is taken as the pad rise position P2 of the second side portion 16. The distance from the second normal line L2 to the excess pad rising position P2 of the second side portion 16 is defined as C2, and the excess pad length at that position is defined as α2 (mm).

[0068] A line L11 is a line that is translated by a length C1 from the first normal line L1 toward the first side portion 15. A line L21 is a line that is translated by a length C2 from the second normal line L2 toward the second side portion 16. An intersection point between a line that passes through intersection point P1 and is parallel to the first line 150c and a line that passes through intersection point P2 and is parallel to the second line 151c is an intersection point P3.

[0069] When defined as above, in the portion on the side of the blank corner portion 17 from the straight line L11 of the first side portion 15 and in the portion on the side of the blank corner portion 17 from the straight line L21 of the blank corner portion 17 and the second side portion 16, the outline line 163 of the material metal plate 10A is on the opposite side of the bottom surface portion 110C, i.e., on the outside, from the broken line consisting of the line segments P1P3 and P3P2.

[0070] Furthermore, when intersections Q1 and Q2 are defined as the intersections between a line that passes through intersection P3 and is perpendicular to the straight line connecting intersection O and intersection P3 and the outline 163 of the raw metal sheet 10A, and the length of line segment Q1Q2 is length B (mm), and the length of line segment P1P2 is length D (mm), the following conditions are satisfied: 0<α1≦h (Formula 1) 0<α2≦h (Formula 2) Furthermore, the following condition is satisfied: 0.3D≦B (Formula 3)

[0071] This embodiment is a raw metal sheet for forming the metal sheet 10 into a shape including the corner shape 124 as described above. According to this embodiment, it is possible to integrally form the metal sheet into a shape including the desired corner shape without using any joints such as welding or adhesive. This allows for excellent formability and suppression of wrinkles and cracks.

[0072] The distance from line segment Q1Q2 to the farthest point on outline 163 of material metal sheet 10A between intersections Q1 and Q2 is defined as C (mm). On the opposite side of blank corner portion 17 with respect to first normal line L1 of first side portion 15 and on the opposite side of blank corner portion 17 with respect to second normal line L2 of second side portion 16, the following relationship may be satisfied: 0 < α < 3h (Formula 4).

[0073] Furthermore, the following expressions may be satisfied: 0.3D≦B≦1.5D (Expression 5) and 0≦C≦2B (Expression 6).

[0074] This allows for better moldability and prevents wrinkles and cracks.

[0075] (Battery Tray) The press-formed metal plate 10B shown in Fig. 10(b) is finished as a product by cutting off excess portions. For example, a battery tray 50 as shown in Fig. 10(c) is finished as a product. The battery tray 50 according to this embodiment will be described with reference to Figs. 14 to 15B.

[0076] In the battery tray 50 according to this embodiment, the base metal plate 10A is a steel plate having a tensile strength of 390 MPa or more. The battery tray 50 has a shape that includes a corner shape 124.

[0077] The corner shape 124 consists of a bottom surface portion 110C, a first ridge line 112c, a second ridge line 113c, a first curved ridge line 152c, a first vertical wall 125c, a second vertical wall 126c, a vertical wall ridge line 121c, a third ridge line 132c, a fourth ridge line 133c, a second curved ridge line 131c, a first flange portion 141c, a second flange portion 142c, and a curved flange portion 143c.

[0078] The bottom surface portion 110C has a shape that includes, as part of its outline, a first straight line 150c, a second straight line 151c, and a first curved line 111c that connects the first straight line 150c and the second straight line 151c.

[0079] The first ridge line 112c is connected to the bottom surface portion 110C by a first straight line 150c. The second ridge line 113c is connected to the bottom surface portion 110C by a second straight line 151c. The first curved ridge line 152c is connected to the bottom surface portion 110C by a first curved line 111c and is also connected to the first ridge line 112c and the second ridge line 113c.

[0080] The first vertical wall 125c rises up and is connected to the first ridge 112c on the opposite side of the bottom surface 110C. The second vertical wall 126c rises up and is connected to the second ridge 113c on the opposite side of the bottom surface 110C.

[0081] The vertical wall ridge line 121c is connected to the first curved ridge line 152c on the opposite side of the bottom surface portion 110C, rises, and is connected to the first vertical wall 125c and the second vertical wall 126c.

[0082] The third ridge 132c connects to the first vertical wall 125c on the side opposite to the first ridge 112c. The fourth ridge 133c connects to the second vertical wall 126c on the side opposite to the second ridge 113c.

[0083] The second curved ridge line 131c connects the vertical wall ridge line 121c on the opposite side of the first curved ridge line 152c and also connects the third ridge line 132c and the fourth ridge line 133c.

[0084] The first flange portion 141c is connected to the third ridge line 132c on the opposite side of the first vertical wall 125c, and the second flange portion 142c is connected to the fourth ridge line 133c on the opposite side of the second vertical wall 126c.

[0085] The curved flange portion 143c connects the second curved ridge line 131c on the opposite side of the vertical wall ridge line 121c and connects the first flange portion 141c and the second flange portion 142c.

[0086] 15A and 15B show schematic cross-sectional views of the battery tray 50 taken along a plane passing through each position of the battery tray 50 shown in FIG. 14. FIG. 15A shows a schematic cross-sectional view of the battery tray 50 taken along a plane passing through position A-A' in FIG. 14 (a position passing through the first vertical wall 125c). FIG. 15B shows a schematic cross-sectional view of the battery tray 50 taken along a plane passing through position B-B' in FIG. 14 (a position passing through the second vertical wall 126c). The distance from the bottom surface 110B to the curved flange portion 143c in a direction perpendicular to the bottom surface 110C of the corner shape 124c is defined as the corner shape height h (mm). When the radius of curvature of the vertical wall ridge 121c is Rb, the angle between the bottom surface portion 110C and the first vertical wall 125c is E1 (°), and the angle between the bottom surface portion 110C and the second vertical wall 126c is E2 (°), the following relationships are satisfied: 1≦h / Rb≦15 (Equation 7), 90°≦E1<105° (Equation 8), and 90°≦E2<105° (Equation 9). The angle E1 (°) is preferably 90°≦E1<95° or 92°≦E1≦100°. The angle E2 (°) is preferably 90°≦E2<95° or 92°≦E2≦100°. Note that θ in FIG. 14 is the angle (°) between the first straight line 150c and the second straight line 151c. The angle θ is preferably in the range of 80°≦θ≦120°.

[0087] The corner shape height h and the curvature radius Rb of the vertical wall ridge line 121c are explained below (Equation 7). If the curvature radius Rb is too small relative to the corner shape height h, it becomes difficult to suppress the formation of a shrink flange even if the corner of the base metal sheet 10A is protruded. Therefore, it is desirable that h / Rb≦15. If the curvature radius Rb is too large relative to the corner shape height h, the loading efficiency of the battery cells on the battery tray 50 decreases, so it is desirable that h / Rb be 1≦h / Rb.

[0088] The angle E1 between the bottom surface portion 110C and the first vertical wall 125c and the angle E2 between the bottom surface portion 110C and the second vertical wall 126c will now be described (Equation 8, Equation 9). If angles E1 and E2 are 90° or less, the vertical walls will form a negative angle with respect to the molding direction of the mold during press molding, making draw molding impossible. Furthermore, if angles E1 and E2 are too large, the loading efficiency of battery cells on the battery tray will decrease. Therefore, it is desirable for angles E1 and E2 to be 90° or greater and less than 105°.

[0089] The metal plate 10A is formed by pressing a single metal plate 10A and does not include any joints between metal plates 10A. The metal plate 10A does not include any joints formed by welding, adhesive, or the like.

[0090] When the thickness of the base metal plate 10A is t (mm), the radius of curvature of the first ridge line 112c is r1 (mm), the radius of curvature of the second ridge line 113c is r2 (mm), the radius of curvature of the third ridge line 132c is r3 (mm), and the radius of curvature of the fourth ridge line 133c is r4 (mm), the following relations are satisfied: 2.5t≦r1≦0.2h (Formula 10) 2.5t≦r2≦0.2h (Formula 11) 2.5t≦r3≦0.2h (Formula 12) 2.5t≦r4≦0.2h (Formula 13) The radius of curvature r1 is preferably in the range of 3t≦r1≦0.1h. The radius of curvature r2 is preferably in the range of 3t≦r2≦0.1h. The radius of curvature r3 is preferably in the range of 3t≦r3≦0.1h. The radius of curvature r4 is preferably 3t≦r4≦0.1h. If the radii of curvature r1, r2, r3, and r4 are too small, the inflow resistance of the material at the ridge line during press forming of a high-strength metal plate increases. Even with the technology disclosed herein, cracks are likely to occur, making forming difficult. Therefore, the radii of curvature r1, r2, r3, and r4 are preferably 2.5 times or more the plate thickness t. Furthermore, if the radii of curvature r1, r2, r3, and r4 are too large, the loading efficiency of the battery cells on the battery tray 50 decreases. Therefore, the radii of curvature r1, r2, r3, and r4 are preferably 0.2h or less.

[0091] According to this embodiment, the battery tray 50 can be integrally molded into a shape including the desired corner shape without using any joints such as welding or adhesive. This allows for excellent formability and suppresses wrinkles and cracks. Furthermore, the battery tray 50 according to this embodiment is lightweight and has excellent strength because the base metal plate 10A is a steel plate with a tensile strength of 390 MPa or more.

[0092] 16-18 , a method for forming a metal sheet according to a second embodiment will be described. In the second embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and their description will be omitted, with only the differences being described. The method for forming a metal sheet (base metal sheet) 10a according to this embodiment is a method for forming a metal sheet 10a by drawing the metal sheet 10a into a shape including a predetermined corner shape 124 using a die apparatus 1000 having a die 100, a punch 200, and a holder 300.

[0093] 13 , a line translated from the first normal line L1 toward the first side portion 15 on the metal plate 10 by a distance 0.5 times the length C1 is defined as a line L12, and a line translated from the second normal line L2 toward the second side portion 16 on the metal plate 10 by a distance 0.5 times the length C2 is defined as a line L22. When the metal plate 10 is disposed in a mold apparatus 1000 for press-forming, a draw bead 165 is provided on the die 100 and the holder 300 at positions corresponding to either or both of a range of the die 100 and the holder 300 opposite the blank corner portion 17 from the line L12 of the first side portion 15 of the metal plate 10 and a range of the second side portion 16 opposite the blank corner portion 17 from the line L22. However, a draw bead 165 is not provided at positions on the die 100 and the holder 300 corresponding to the first side portion 15, the second side portion 16, and the blank corner portion 17 between the line L12 and the line L22 of the metal plate 10. The region between the first normal line L1 and the straight line L12 and the region between the second normal line L2 and the straight line L22 are portion F. No draw bead 165 is provided at a position of the die 100 and holder 300 corresponding to portion F. FIG. 18 shows an example of a draw bead 165 provided on the holder 300 at an arrangement position on the metal plate 10a indicated by a dotted line. This shows a case where the draw bead 165 is provided on the die 100 and the holder 300 corresponding to both a range on the opposite side of the blank corner portion 17 from the straight line L12 of the first side portion 15 of the metal plate 10a and a range on the opposite side of the blank corner portion 17 from the straight line L22 of the second side portion 16 of the metal plate 10a, and is used for molding. FIG. 17 shows the corresponding position of the draw bead 165 on the metal plate 10a when a die apparatus 1000 provided with the draw bead 165 is used.

[0094] By providing the drawbeads 165 in this manner, the inflow resistance of the first flange portion 141c and the second flange portion 142c increases, reducing the amount of inflow. This alleviates compression of the flange portions (portions F) on both sides of the curved flange portion 143c. As a result, the inflow of material into the first flange portion 141c and the second flange portion 142c is somewhat suppressed, but the inflow of material into the corners, which can lead to cracking, is further improved.

[0095] (Molding Apparatus) An example of a molding apparatus that can be used in the first and second embodiments will be described with reference to Fig. 16. The molding apparatus 1000 includes a die 100, a holder 300, and a punch 200, as shown in Fig. 16, for example.

[0096] The die 100, holder 300, and punch 200 are arranged facing each other in this order. The punch 200 has a protrusion 223 on the surface facing the holder 300. The die 100 has a recess 123 on the surface facing the holder 300. When the die 100 and the punch 200 move relatively in the direction P toward each other (press direction), the protrusion 223 of the punch 200 is pressed into the recess 123 of the die 100. The holder 300 has a press hole 323. When the holder 300 and the punch 200 move relatively in the direction P toward each other, the protrusion 223 of the punch 200 penetrates the press hole 323 of the holder 300.

[0097] A raw metal sheet 10A, which is the workpiece, is placed between the punch 200 and the holder 300. In this state, the die 100 and the punch 200 move relatively in the pressing direction, thereby plastically deforming the raw metal sheet 10A.

[0098] The die 100, punch 200, and holder 300 may each be composed of a single member, or may each be composed of a separate mold. The mold device 1000 may also include molds other than these molds.

[0099] In the above embodiment, the battery tray 50 may be a final product, or may be an intermediate product that is to be further processed (by press forming, cutting, bending, welding, heating / cooling, plating, or painting) to form a final product.

[0100] Examples of the present disclosure will be described below. First, Examples 1 to 12 will be described. Examples 4, 10, and 12 are examples of the present invention, while Examples 1, 2, 3, 5, 6, 7, 8, 9, and 11 are comparative examples for explaining the effects of the present invention. Figure 19 shows an outline of the shape of the final product in Examples 1 to 12. The final product refers to the processed material metal sheet obtained by press-forming a material metal sheet into a formed shape and then trimming the outer periphery.

[0101] The bottom surface portion 110d has a generally rectangular shape with a width We and a length Le. The bottom surface portion 110d is connected to the vertical wall 125d and the vertical wall ridgeline 121d via the punch shoulder ridgeline 112d, and the vertical wall 125d and the vertical wall ridgeline 121d are connected to the flange portion 141d via the die shoulder ridgeline 132d, forming a deep-drawn rectangular cylinder shape with four corners. Comparing the corner shapes in Figure 19 and Figure 12, the bottom surface portion 110d corresponds to the bottom surface portion 110C, the vertical wall 125d corresponds to the first vertical wall 125c and the second vertical wall 126c, the vertical wall ridgeline 121d corresponds to the vertical wall ridgeline 121c, and the flange portion 141d corresponds to the first flange portion 141c, the second flange portion 142c, and the curved flange portion 143c. The punch shoulder ridge 112d corresponds to the first ridge 112c, the second ridge 113c, and the first curved ridge 152c, and the die shoulder ridge 132d corresponds to the third ridge 132c, the fourth ridge 133c, and the second curved ridge 131c. Here, the radius of curvature of the short side of the straight portion of the punch shoulder ridge 112d is defined as the short side punch shoulder ridge radius rep1. The radius of curvature of the long side of the straight portion of the punch shoulder ridge is defined as the long side punch shoulder ridge radius rep2. The radius of curvature of the short side of the straight portion of the die shoulder ridge 132d is defined as the short side die shoulder ridge radius red1. The radius of curvature of the long side of the straight portion of the die shoulder ridge 132d is defined as the long side die shoulder ridge radius red2. The radius of curvature of the vertical wall ridge 121d is defined as reb. Comparing Figures 14 to 15B with Figure 12, reb corresponds to Rb, the radius of curvature of the vertical wall ridge line 121c in Figure 13. rep1 and rep2 correspond to r1 and r2 in Figure 14. red1 and red2 correspond to r3 and r4 in Figure 14. The vertical distance from the bottom surface portion 110d to the flange portion 141d is defined as height He. Height He corresponds to corner shape height h in Figure 14. θe is the angle formed by the long side and short side of the straight line portion of the outline of the bottom surface portion 110d. θe corresponds to θ in Figure 13.

[0102] In Examples 1 to 6 and Example 8, the width We of the bottom portion, the length Le of the bottom portion, the height He, the radius (radius of curvature) Rb of the vertical wall ridge, the radius rep1 of the short side punch shoulder ridge, the radius rep2 of the long side punch shoulder ridge, the radius red of the short side die shoulder ridge, and the radius red2 of the long side die shoulder ridge were the values ​​shown in Shape 1 in Table 1, and further, the shape of the final product was such that θe was 90°, the angle of the vertical wall relative to the bottom surface (corresponding to E1 and E2 in Figures 15A and 15B) was 92°, and the flange width was 30 mm. In Example 7, the width We of the bottom portion, the length Le of the bottom portion, the height He, the vertical wall ridge radius Rb, the shoulder ridge radius rep1 of the short side punch, the shoulder ridge radius rep2 of the long side punch, the shoulder ridge radius red of the short side die, and the shoulder ridge radius red2 of the long side die were the values ​​shown in Shape 3 of Table 1, and further, θe was 90°, the angle of the vertical wall relative to the bottom surface was 92°, and the flange width was 30 mm. In Examples 9 to 12, the width We of the bottom portion, the length Le of the bottom portion, the height He, the vertical wall ridge radius Rb, the shoulder ridge radius rep1 of the short side punch, the shoulder ridge radius rep2 of the long side punch, the shoulder ridge radius red of the short side die, and the shoulder ridge radius red2 were the values ​​shown in Shape 2 of Table 1, and further, θe was 90°, the angle of the vertical wall relative to the bottom surface was 92°, and the flange width was 30 mm.

[0103]

[0104] As the base metal plate, Examples 1 and 2 used a steel plate (270 MPa material) having a tensile strength of 270 MPa, a plate thickness of 1 mm, and an elongation EL of 49%, Examples 3 to 8 used a steel plate (590 MPa material) having a tensile strength of 590 MPa, a plate thickness of 1 mm, and an elongation EL of 30%, Examples 9 to 11 used a steel plate (980 MPa material) having a tensile strength of 980 MPa, a plate thickness of 1 mm, and an elongation EL of 20%, and Example 12 used an aluminum plate having a tensile strength of 240 MPa, a plate thickness of 1 mm, and an elongation EL of 22%. The shape of the material metal plate was a rectangle as shown in FIG. 20A in Example 1, a shape in which only the corners (the blank corners 17 between the first normal line L1 and the second normal line L2 in FIG. 13 ) protruded as shown in FIG. 20B in Examples 2 and 3, and a shape in which only the corners and their surroundings (including the blank corners 17 in FIG. 13 , from the line L11 of the first side 15 to the line L21 of the second side 16 to the blank corners 17) protruded as shown in FIG. 20C in Examples 4 and 7. In Example 5, the overall length was increased by 500 mm compared to the shape of FIG. 20C , and the protruding portions were also elongated accordingly. In Example 6, the protruding height of the central portion of the protruding portion was shortened and the protruding height of the end portions of the protruding portion was increased, and the length B of the line segment Q1Q2 in FIG. 13 was shortened and the length D of the line segment P1P2 was increased. In Example 8, the shape of the protruding portion of the base metal plate was changed from the shape shown in Figure 20C by reducing the length D of line segment P1P2 and increasing the length B of line segment Q1Q2, so that length B was greater than length D, i.e., the width of the tip was wider than the base of the protrusion. In Examples 9 to 12, the base metal plate was shaped so that the corners and their surroundings protruded as shown in Figure 20D.

[0105] In all examples, a die 1000X consisting of a punch 200X, a die 100X, and a holder 300X, as shown in FIG. 21, was used. The periphery of the raw metal sheet was pressed against the die 100X by the holder 300X, and the central portion of the raw metal sheet was pressed from the holder 300X side of the raw metal sheet toward the die 100X by the punch 200X to form the sheet. The die shape was adapted to the forming shape for each example. FIG. 21 shows an overview of the die configuration and layout, and the detailed die shape differs depending on the example. Furthermore, in Examples 1 to 9 and 12, no drawbeads were provided on the die, while in Examples 10 and 11, drawbeads were provided on the holder and die of the die. FIG. 22A shows the position of the drawbead on the holder in Example 10. Furthermore, for the die of the die in Example 10, a paired drawbead was provided at a location that paired with the drawbead position on the holder. In Example 11, a drawbead was provided at the position on the holder shown in FIG. 22B , and a paired drawbead was also provided on the die at a position on the holder that paired with the drawbead, as in Example 10. The length of the drawbead in Example 10 is within the range on the opposite side of the blank corner portion 17 from the straight line L12 of the first side portion 15 in FIG. 13 and within the range on the opposite side of the blank corner portion 17 from the straight line L22 of the second side portion 16. On the other hand, the drawbead in Example 11 is longer than the drawbead in Example 10. That is, the drawbead in Example 11 is arranged not only within the range on the opposite side of the blank corner portion 17 from the straight line L12 of the first side portion 15 in FIG. 13 and within the range on the opposite side of the blank corner portion 17 from the straight line L22 of the second side portion 16, but also within a range that includes the range on the blank corner portion 17 side from the straight line L12 of the first side portion 15 and the range on the blank corner portion 17 side from the straight line L22 of the second side portion 16.

[0106] Table 2 shows the main conditions of Examples 1 to 12 and whether or not cracks occurred.

[0107]

[0108] In Example 1, the base metal sheet was formed using a 270 MPa material with a rectangular shape as shown in Figure 20A, but the shrinkage flange caused insufficient material flow, resulting in cracks. In contrast, in Example 2, the same 270 MPa material was used to form a base metal sheet with a shape with a protrusion as shown in Figure 20B. This suppressed the shrinkage flange, increased material flow, and reduced cracking. However, in Example 3, under the same conditions as Example 2, the base metal sheet was changed to a 590 MPa material with a lower elongation EL than the 270 MPa material. Material flow was insufficient, resulting in cracks occurring at the vertical wall ridges. This is because the protruding portion of Shape 2 was only the corner (blank corner portion 17 between the first normal line L1 and the second normal line L2 in Figure 13), resulting in insufficient improvement in material flow. Therefore, in Example 4, under the same conditions as Example 3, the shape of the base metal sheet was changed to the protruding corner and its surrounding area (including the blank corner portion 17 in FIG. 13 , from the line L11 of the first side portion 15 to the line L21 of the second side portion 16) as shown in FIG. 20C . This resulted in improved material flow compared to Example 3. Therefore, in Example 4, even a 590 MPa material with a lower elongation EL than a 270 MPa material could be formed while suppressing cracking. In Example 5, the base metal sheet was larger than in Example 4, resulting in α1 of 3h or more. This resulted in a greater distance in the material flow direction from the protruding portion to the portion corresponding to the curved flange. As a result, the protruding portion's effect of suppressing flange shrinkage was reduced, reducing material flow and causing cracking at the vertical wall ridge. In Example 6, the shape of the protruding portion was changed compared to Example 4, increasing the length D of line segment P1P2 and shortening the length B of line segment Q1Q2, resulting in B being 0.3D or less. This resulted in a shape closer to a rectangular shape. As a result, the shrink flange suppression effect was reduced, material flow was suppressed, and cracks occurred at the vertical wall ridges. In Example 7, the short-side die shoulder ridge radius red1 and the long-side die shoulder ridge radius red2 were reduced to 2.4 mm compared to Example 4. Because the die shoulder ridge radii were reduced and red1 (r2) and red2 (r2) were smaller than 2.5t, the flow resistance at the ridges during molding increased. As a result, material flow decreased and cracks occurred at the vertical wall ridges. In Example 8, compared to Example 4, the shape of the protruding portion was changed to shorten the length D of line segment P1P2 and increase the length B of line segment Q1Q2, so that B was 1.5 or more.As a result, the shape of the protruding corner was wider at the tip than at the base, resulting in a concave shape on the side of the protruding portion. As a result, deformation concentrated at the end of the concave side, causing cracks. In Example 9, compared to Example 4, a 980 MPa steel sheet with the shape shown in Figure 20D was used. Because the 980 MPa steel has a lower elongation (EL) than the 590 MPa steel, cracks occurred at the vertical wall ridge even in a shape with a protruding portion. In contrast to Example 9, in Example 10, drawbeads were provided within the range opposite the blank corner portion 17 from the line L12 of the first side portion 15 of the mold in Figure 13 and within the range opposite the blank corner portion 17 from the line L22 of the second side portion 16 of the mold. This reduced compression of the flange portions (portions F) on both sides of the curved flange portion. As a result, material flow was increased, and cracks were suppressed even in the 980 MPa steel with low elongation (EL) during forming. However, in Example 11, the drawbeads were longer than in Example 10. In Example 11, the drawbead was positioned not only within the range opposite the blank corner portion 17 from the straight line L12 of the first side portion 15 and the range opposite the blank corner portion 17 from the straight line L22 of the second side portion 16 in FIG. 13 , but also within a range including the range on the blank corner portion 17 side from the straight line L12 of the first side portion 15 and the range on the protruding portion 13 side from the straight line L22 of the second side portion 16. This resulted in increased material inflow resistance at the flange portions (portions F) on both sides of the curved flange portion. As a result, in Example 11, the material inflow was reduced compared to Example 10, and cracks occurred at the vertical wall ridge line. In Example 12, unlike Example 9, the type of base metal plate was an aluminum plate. Therefore, in Example 12, according to the disclosed technology, cracks could be suppressed and formed even when the base metal plate was made of a material other than a steel plate.

[0109] Next, Examples 13 to 16 will be described. The shape of the final product of Example 13 is shown in Figure 23A, and the shape of the final product of Example 14 is shown in Figure 23B. Example 13 was formed using a steel plate with a tensile strength of 590 MPa, a thickness of 1.2 mm, and an elongation EL of 30%. Example 14 was formed using a steel plate with a tensile strength of 590 MPa, a thickness of 0.8 mm, and an elongation EL of 30%. As described above, according to the disclosed technology, it is possible to form well even if the bottom shape is not rectangular, but is trapezoidal or a shape other than a square, such as an octagon. The shape of the final product of Example 15 is shown in Figure 23C. Example 15 was formed using a steel plate with a tensile strength of 590 MPa, a thickness of 1.6 mm, and an elongation EL of 30%. As described above, according to the disclosed technology, it is possible to form well even shapes including corner shapes, but where the vertical walls and flanges are not continuous all around. In Example 16, a steel plate having a tensile strength of 590 MPa, a thickness of 1.2 mm, and an elongation EL of 30% was pre-processed into the shape shown in Fig. 24A as a base metal plate, and then formed into the shape shown in Fig. 24B using the disclosed technology. In this way, the disclosed technology allows the pre-processed metal plate to be used as a base metal plate.

[0110] According to the present disclosure, it is possible to provide a metal plate forming method, a raw metal plate, and a battery tray for integrally forming a shape including a corner shape with a small radius of curvature of each ridge line connecting a vertical wall, a bottom surface, and a flange using a high-strength metal plate.

[0111] 10 Metal plate 10A, 10a, 10V1, 10V2, 10V3, 10V4 Material metal plate 10B Metal plate (after press forming) 10C Metal plate (after trimming) 11 Corner portion 13 Protruding portion 15 First side portion 16 Second side portion 17 Blank corner portion 50 Battery tray 100 Die 110A, 110B, 110C Bottom portion 111c First curved line 112c First ridge line 113c Second ridge line 121c Vertical wall ridge line 124 Corner shape 125c First vertical wall 126c Second vertical wall 131c Second curved ridge line 132c Third ridge line 133c Fourth ridge line 141c First flange portion 142c Second flange portion 143c, 143V1, 143V2, 143V3 Curved flange portion 144V1, 144V2, 144V3 Corner portion 150c First straight line 151c Second straight line 152 Third straight line 152c First curved ridge line 153 Second curved line 154 Fourth straight line 162 Virtual developed shape 162E End portion of final product 163 Outline line (of raw metal plate) 164 Outline line (of bottom portion) 165 Draw bead 200 Punch 300 Holder 1000 Die device

Claims

1. A bottom surface portion having a shape including, as part of its outline, a first straight line, a second straight line, and a first curved line connecting the first straight line and the second straight line; a first ridge line connected to the bottom surface portion by the first straight line; a second ridge line connected to the bottom surface portion by the second straight line; a first curved ridge line connected to the bottom surface portion by the first curved line and connecting the first ridge line and the second ridge line; a first vertical wall connecting the first ridge line and rising on the opposite side of the bottom surface portion; a second vertical wall connecting the second ridge line and rising on the opposite side of the bottom surface portion; a vertical wall ridge line connecting the first curved ridge line and rising on the opposite side of the bottom surface portion and connecting the first vertical wall and the second vertical wall; a third ridge line connecting the first vertical wall and the opposite side of the first ridge line; and a fourth ridge line connecting the second vertical wall and the opposite side of the second ridge line. a second curved ridge line connecting the vertical wall ridge line on the opposite side to the first curved ridge line and connecting the third ridge line and the fourth ridge line, a first flange portion connecting the third ridge line on the opposite side to the first vertical wall and extending substantially horizontally, a second flange portion connecting the fourth ridge line on the opposite side to the second vertical wall and extending substantially horizontally, and a curved flange portion connecting the second curved ridge line on the opposite side to the vertical wall ridge line, extending substantially horizontally and connecting the first flange portion and the second flange portion, wherein the corner shape is defined as a bottom portion outer length at each position on the outline line of the bottom portion consisting of the first straight line, the second straight line, and the first curved line, when a cross section of the corner shape is viewed on a plane perpendicular to the outline line of the bottom portion, the cross-sectional length from the outline line of the bottom portion to an end of a product on the cross section is defined as a bottom portion outer length at each outline line position of the bottom portion, A virtual developed shape is a shape obtained by extending the bottom surface portion at each position on the outline of the bottom surface portion in a direction parallel to the bottom surface portion and perpendicular to the outline of the bottom surface portion by the outer length of the bottom surface portion at each position on the outline of the bottom surface portion, a portion of the outline of the virtual developed shape that extends from the first straight line of the bottom surface portion is a third straight line, a portion of the outline of the virtual developed shape that extends from the first curved line of the bottom surface portion is a second curved line, and a portion of the outline of the virtual developed shape that extends from the second straight line of the bottom surface portion is a fourth straight line,a shape of a portion of the material metal plate including the corner shape, when viewed in a cross section on a plane perpendicular to the outline of the bottom surface portion at each position on the outline of the bottom surface portion, is the same as the imaginary developed shape or is a shape that is parallel to the bottom surface portion and extends further than the imaginary developed shape in a direction perpendicular to the outline of the bottom surface portion at each position on the outline of the bottom surface portion; a length extended from the outline of the imaginary developed shape to the outline of the material metal plate at each cross section position is defined as an excess pad length α; furthermore, a joint between the first straight line and the first curved line is defined as point b1, a joint between the second straight line and the first curved line is defined as point b2, a line that passes through point b1, is parallel to the bottom surface portion and perpendicular to the first straight line is defined as a first normal line L1, a line that passes through point b2, is parallel to the bottom surface portion and perpendicular to the second straight line is defined as a second normal line L2, and an intersection of the first normal line L1 and the second normal line L2 is defined as point O; a first side portion is a side of the material metal plate other than the bottom surface portion and not including the second curved line with respect to the first normal line L1, a second side portion is a side of the material metal plate other than the bottom surface portion and not including the second curved line with respect to the second normal line L2, and a blank corner portion is a portion of the material metal plate other than the bottom surface portion and between the first normal line L1 and the second normal line L2, and a corner shape height h is a distance from the bottom surface portion to the curved flange portion in a direction perpendicular to the bottom surface portion of the corner shape, When the excess metal length α is viewed along the first straight line in the direction opposite to the blank corner portion from the first normal line L1 in the first side portion of the raw metal plate, if the position on the outline of the raw metal plate where the excess metal length α first takes a minimum value is within 3h from the first normal line L1, the position on the outline of the raw metal plate where the excess metal length α first takes a minimum value from the first normal line L1 is defined as the excess metal rise position of the first side portion, and if the excess metal length α does not take a minimum value within 3h from the first normal line L1, the position on the outline of the raw metal plate where the excess metal length α first takes a minimum value within 3h from the first normal line L1 is defined as the excess metal rise position of the first side portion, the distance from the first normal line L1 to the excess metal rise position of the first side portion is defined as C1, and the excess metal length at that position is defined as α1,When the excess metal length α is viewed along the second straight line in the direction opposite to the blank corner portion from the second normal line L2 in the second side portion of the raw metal plate, if the position on the outline of the raw metal plate where the excess metal length α first takes a minimum value is within 3h from the second normal line L2, the position on the outline of the raw metal plate where the excess metal length α first takes a minimum value from the second normal line L2 is defined as the excess metal rise position of the second side portion, and if the excess metal length α does not take a minimum value within 3h from the second normal line L2, the position on the outline of the raw metal plate where the excess metal length α first takes a minimum value within 3h from the second normal line L2 is defined as the excess metal rise position of the second side portion, the distance from the second normal line L2 to the excess metal rise position of the second side portion is defined as C2, and the excess metal length at that position is defined as α2, If an intersection point P1 is an intersection between a straight line L11 moved parallel to the first side portion by a length C1 from the first normal line L1 and the outline of the raw metal plate, an intersection point P2 is an intersection between a straight line L21 moved parallel to the second side portion by a length C2 from the second normal line L2 and the outline of the raw metal plate, and an intersection point P3 is an intersection between a straight line that passes through the intersection point P1 and is parallel to the first straight line and a straight line that passes through the intersection point P2 and is parallel to the second straight line, then in a portion of the first side portion on the side of the blank corner portion from the straight line L11 and in a portion of the blank corner portion and the second side portion on the side of the straight line L21, the outline of the raw metal plate is on the opposite side to the bottom portion, i.e., on the outside, of a broken line formed by line segments P1P3 and P3P2, Furthermore, when the intersection points Q1 and Q2 are the intersection points between a line that passes through the intersection point P3 and is perpendicular to the straight line connecting the intersection point O and the intersection point P3 and the outline line of the raw metal plate, the length of the line segment Q1Q2 is length B and the length of the line segment P1P2 is length D, the method for forming a metal plate is characterized in that: 0<α1≦h (Equation 1) 0<α2≦h (Equation 2) is satisfied; and 0.3D≦B (Equation 3) is also satisfied.

2. The forming method of a metal plate as described in claim 1, comprising a press forming process and a trimming process, characterized in that, when the distance from the line segment Q1Q2 to the furthest point on the outline of the raw metal plate between the intersection points Q1 and Q2 is C, the following conditions are satisfied on the opposite side of the blank corner portion with respect to the first normal line L1 of the first side portion and the opposite side of the blank corner portion with respect to the second normal line L2 of the second side portion: 0<α<3h (Formula 4), and further, 0.3D≦B≦1.5D (Formula 5) 0≦C≦2B (Formula 6).

3. A bottom surface portion having a shape including, as part of its outline, a first straight line, a second straight line, and a first curved line connecting the first straight line and the second straight line; a first ridge line connected to the bottom surface portion by the first straight line; a second ridge line connected to the bottom surface portion by the second straight line; a first curved ridge line connected to the bottom surface portion by the first curved line and connecting the first ridge line and the second ridge line; a first vertical wall connecting the first ridge line and rising on the opposite side of the bottom surface portion; a second vertical wall connecting the second ridge line and rising on the opposite side of the bottom surface portion; a vertical wall ridge line connecting the first curved ridge line and rising on the opposite side of the bottom surface portion and connecting the first vertical wall and the second vertical wall; a third ridge line connecting the first vertical wall and the opposite side of the first ridge line; and a fourth ridge line connecting the second vertical wall and the opposite side of the second ridge line. a first flange portion connected to the opposite side of the third ridgeline and the first curved ridgeline and connecting the third ridgeline and the fourth ridgeline, a second flange portion connected to the opposite side of the third ridgeline and the first vertical wall and extending substantially horizontally, a second flange portion connected to the opposite side of the fourth ridgeline and the second vertical wall and extending substantially horizontally, and a curved flange portion connected to the opposite side of the second curved ridgeline and the vertical wall ridgeline and extending substantially horizontally and connecting the first flange portion and the second flange portion, wherein the corner shape is formed into a shape including a corner shape consisting of a bottom portion outer length at each position on the outer line of the bottom portion consisting of the first straight line, the second straight line, and the first curved line, when the cross section of the corner shape is viewed on a plane perpendicular to the outer line of the bottom portion, the cross-sectional length from the outer line of the bottom portion to an end of a product on the cross section is defined as the bottom portion outer length at each position of the outer line of the bottom portion, A virtual developed shape is a shape obtained by extending the bottom surface portion at each position on the outline of the bottom surface portion in a direction parallel to the bottom surface portion and perpendicular to the outline of the bottom surface portion by the outer length of the bottom surface portion at each position on the outline of the bottom surface portion, a portion of the outline of the virtual developed shape that extends from the first straight line of the bottom surface portion is a third straight line, a portion of the outline of the virtual developed shape that extends from the first curved line of the bottom surface portion is a second curved line, and a portion of the outline of the virtual developed shape that extends from the second straight line of the bottom surface portion is a fourth straight line,a shape of a portion of a material metal plate formed into the corner shape, when viewed in cross section on a plane perpendicular to the outline of the bottom surface portion at each position on the outline of the bottom surface portion, is the same as the imaginary developed shape or is a shape extended further than the imaginary developed shape in a direction parallel to the bottom surface portion and perpendicular to the outline of the bottom surface portion, a length extended from the outline of the imaginary developed shape to the outline of the material metal plate at each cross-sectional position is defined as an excess pad length α, a joint between the first straight line and the first curved line is defined as point b1, a joint between the second straight line and the first curved line is defined as point b2, a line passing through point b1, parallel to the bottom surface portion and perpendicular to the first straight line is defined as a first normal line L1, a line passing through point b2, parallel to the bottom surface portion and perpendicular to the second straight line is defined as a second normal line L2, and an intersection of the first normal line L1 and the second normal line L2 is defined as point O, a first side portion is a side of the material metal plate other than the bottom surface portion and not including the second curved line with respect to the first normal line L1, a second side portion is a side of the material metal plate other than the bottom surface portion and not including the second curved line with respect to the second normal line L2, and a blank corner portion is a portion of the material metal plate other than the bottom surface portion and between the first normal line L1 and the second normal line L2, and a corner shape height h is a distance from the bottom surface portion to the curved flange portion in a direction perpendicular to the bottom surface portion of the corner shape, When the excess metal length α is viewed along the first straight line in the direction opposite to the blank corner portion from the first normal line L1 in the first side portion of the raw metal plate, if the position on the outline of the raw metal plate where the excess metal length α first takes a minimum value is within 3h from the first normal line L1, the position on the outline of the raw metal plate where the excess metal length α first takes a minimum value from the first normal line L1 is defined as the excess metal rise position of the first side portion, and if the excess metal length α does not take a minimum value within 3h from the first normal line L1, the position on the outline of the raw metal plate where the excess metal length α first takes a minimum value within 3h from the first normal line L1 is defined as the excess metal rise position of the first side portion, the distance from the first normal line L1 to the excess metal rise position of the first side portion is defined as C1, and the excess metal length at that position is defined as α1,When the excess metal length α is viewed along the second straight line in the direction opposite to the blank corner portion from the second normal line L2 in the second side portion of the raw metal plate, if the position on the outline of the raw metal plate where the excess metal length α first takes a minimum value is within 3h from the second normal line L2, the position on the outline of the raw metal plate where the excess metal length α first takes a minimum value from the second normal line L2 is defined as the excess metal rise position of the second side portion, and if the excess metal length α does not take a minimum value within 3h from the second normal line L2, the position on the outline of the raw metal plate where the excess metal length α first takes a minimum value within 3h from the second normal line L2 is defined as the excess metal rise position of the second side portion, the distance from the second normal line L2 to the excess metal rise position of the second side portion is defined as C2, and the excess metal length at that position is defined as α2, If an intersection point P1 is an intersection between a straight line L11 moved parallel to the first side portion by a length C1 from the first normal line L1 and the outline of the raw metal plate, an intersection point P2 is an intersection between a straight line L21 moved parallel to the second side portion by a length C2 from the second normal line L2 and the outline of the raw metal plate, and an intersection point P3 is an intersection between a straight line that passes through the intersection point P1 and is parallel to the first straight line and a straight line that passes through the intersection point P2 and is parallel to the second straight line, then in a portion of the first side portion on the side of the blank corner portion from the straight line L11 and in a portion of the blank corner portion and the second side portion on the side of the straight line L21, the outline of the raw metal plate is on the opposite side to the bottom portion, i.e., on the outside, of a broken line formed by line segments P1P3 and P3P2, Furthermore, when the intersection points Q1 and Q2 of a line passing through the intersection P3 and perpendicular to the straight line connecting the intersection O and the intersection P3 with the outline of the raw metal plate are taken as intersection points Q1 and Q2, the length of the line segment Q1Q2 is taken as length B and the length of the line segment P1P2 is taken as length D, the raw metal plate satisfies 0<α1≦h (Equation 1) 0<α2≦h (Equation 2) and further satisfies 0.3D≦B (Equation 3).

4. The raw metal plate according to claim 3, characterized in that, when the distance from the line segment Q1Q2 to the furthest point on the outline of the raw metal plate between the intersection points Q1 and Q2 is C, the following is satisfied on the opposite side of the blank corner portion with respect to the first normal line L1 of the first side portion and the opposite side of the blank corner portion with respect to the second normal line L2 of the second side portion: 0<α<3h (Formula 4), and further 0.3D≦B≦1.5D (Formula 5) 0≦C≦2B (Formula 6).

5. A bottom surface portion having a shape including a first straight line, a second straight line, and a first curved line connecting the first straight line and the second straight line as part of the outer shape, a first ridge line connected to the bottom surface portion by the first straight line, a second ridge line connected to the bottom surface portion by the second straight line, a first curved ridge line connected to the bottom surface portion by the first curved line and connecting the first ridge line and the second ridge line, a first vertical wall connecting the first ridge line and rising on the opposite side of the bottom surface portion, a second vertical wall connecting the second ridge line and rising on the opposite side of the bottom surface portion, a vertical wall ridge line connecting the first curved ridge line and rising on the opposite side of the bottom surface portion and connecting the first vertical wall and the second vertical wall, a third ridge line connecting the first vertical wall and the opposite side of the first ridge line, and a fourth ridge line connecting the second vertical wall and the opposite side of the second ridge line. a second curved ridgeline connecting the vertical wall ridgeline on the opposite side to the first curved ridgeline and connecting the third ridgeline and the fourth ridgeline, a first flange portion connecting the third ridgeline and the opposite side to the first vertical wall and extending substantially horizontally, a second flange portion connecting the fourth ridgeline and the opposite side to the second vertical wall and extending substantially horizontally, and a curved flange portion connecting the second curved ridgeline and the opposite side to the vertical wall ridgeline, extending substantially horizontally and connecting the first flange portion and the second flange portion, wherein the corner shape is formed by drawing a metal plate using a die device having a die, a punch, and a holder, the corner shape being defined as a bottom portion outer length at each position on the outline line of the bottom portion consisting of the first straight line, the second straight line, and the first curved line, when a cross section of the corner shape is viewed on a plane perpendicular to the outline line of the bottom portion, the cross-sectional length from the outline line of the bottom portion to an end of a product on the cross section is defined as a bottom portion outer length at each outline line position of the bottom portion, A virtual developed shape is a shape obtained by extending the bottom surface portion at each position on the outline of the bottom surface portion in a direction parallel to the bottom surface portion and perpendicular to the outline of the bottom surface portion by the outer length of the bottom surface portion at each position on the outline of the bottom surface portion, a portion of the outline of the virtual developed shape that extends from the first straight line of the bottom surface portion is a third straight line, a portion of the outline of the virtual developed shape that extends from the first curved line of the bottom surface portion is a second curved line, and a portion of the outline of the virtual developed shape that extends from the second straight line of the bottom surface portion is a fourth straight line,a shape of a portion of a material metal plate formed into the corner shape, when viewed in cross section on a plane perpendicular to the outline of the bottom surface portion at each position on the outline of the bottom surface portion, is the same as the imaginary developed shape or is a shape extended further than the imaginary developed shape in a direction parallel to the bottom surface portion and perpendicular to the outline of the bottom surface portion, a length extended from the outline of the imaginary developed shape to the outline of the material metal plate at each cross-sectional position is defined as an excess pad length α, a joint between the first straight line and the first curved line is defined as point b1, a joint between the second straight line and the first curved line is defined as point b2, a line passing through point b1, parallel to the bottom surface portion and perpendicular to the first straight line is defined as a first normal line L1, a line passing through point b2, parallel to the bottom surface portion and perpendicular to the second straight line is defined as a second normal line L2, and an intersection of the first normal line L1 and the second normal line L2 is defined as point O, a first side portion is a side of the material metal plate other than the bottom surface portion and not including the second curved line with respect to the first normal line L1, a second side portion is a side of the material metal plate other than the bottom surface portion and not including the second curved line with respect to the second normal line L2, and a blank corner portion is a portion of the material metal plate other than the bottom surface portion and between the first normal line L1 and the second normal line L2, and a corner shape height h is a distance from the bottom surface portion to the curved flange portion in a direction perpendicular to the bottom surface portion of the corner shape, When the excess metal length α is viewed along the first straight line in the direction opposite to the blank corner portion from the first normal line L1 in the first side portion of the raw metal plate, if the position on the outline of the raw metal plate where the excess metal length α first takes a minimum value is within 3h from the first normal line L1, the position on the outline of the raw metal plate where the excess metal length α first takes a minimum value from the first normal line L1 is defined as the excess metal rise position of the first side portion, and if the excess metal length α does not take a minimum value within 3h from the first normal line L1, the position on the outline of the raw metal plate where the excess metal length α first takes a minimum value within 3h from the first normal line L1 is defined as the excess metal rise position of the first side portion, and the distance from the first normal line L1 to the excess metal rise position of the first side portion is defined as C1,when the excess metal length α is viewed along the second straight line in the direction opposite to the blank corner portion from the second normal line L2 in the second side portion of the raw metal plate, if the position on the outline of the raw metal plate where the excess metal length α first takes a minimum value is within 3h from the second normal line L2, the position on the outline of the raw metal plate where the excess metal length α first takes a minimum value from the second normal line L2 is defined as the excess metal rise position of the second side portion, if the excess metal length α does not take a minimum value within 3h from the second normal line L2, the position on the outline of the raw metal plate where the excess metal length α first takes a minimum value within 3h from the second normal line L2 is defined as the excess metal rise position of the second side portion, the distance from the second normal line L2 to the excess metal rise position of the second side portion is defined as C2, and the excess metal length at that position is defined as α2, and a straight line translated in parallel from the first normal line L1 toward the first side portion on the metal plate by a distance 0.5 times the length C1 is defined as a straight line L12, the straight line L22 is a straight line that is shifted in parallel from the second normal line L2 toward the second side portion on the metal plate by a distance 0.5 times the length C2; and a draw bead is provided at a position of the die and the holder corresponding to both or either of a range of the first side portion from the straight line L12 to the opposite side of the blank corner portion and a range of the second side portion from the straight line L22 to the opposite side of the blank corner portion, and no draw bead is provided at a position of the die and the holder corresponding to the first side portion, the second side portion, and the blank corner portion between the straight line L12 and the straight line L22.

6. The method for forming a metal plate according to claim 1 or 2, characterized in that the base metal plate is a steel plate having a tensile strength of 390 MPa or more.

7. The base metal plate according to claim 3 or 4, characterized in that the base metal plate is a steel plate having a tensile strength of 390 MPa or more.

8. A battery tray having a shape including a corner, the corner shape being made of a steel plate having a tensile strength of 390 MPa or more, the bottom surface portion having a shape including, as part of an outline, a first straight line, a second straight line, and a first curved line connecting the first straight line and the second straight line, a first ridge line connected to the bottom surface portion by the first straight line, a second ridge line connected to the bottom surface portion by the second straight line, a first curved ridge line connected to the bottom surface portion by the first curved line and connecting the first ridge line and the second ridge line, a first vertical wall connecting and rising from the opposite side of the bottom surface portion to the first ridge line, a second vertical wall connecting and rising from the opposite side of the bottom surface portion to the second ridge line, a vertical wall ridge line connecting and rising from the opposite side of the first curved ridge line to the bottom surface portion and connecting the first vertical wall and the second vertical wall, and a third ridge line connecting the first vertical wall to the opposite side of the first ridge line. a fourth ridgeline connecting the second vertical wall and the second ridgeline on an opposite side thereof; a second curved ridgeline connecting the vertical wall ridgeline and the first curved ridgeline on an opposite side thereof and connecting the third ridgeline and the fourth ridgeline; a first flange portion connecting the third ridgeline and the first vertical wall on an opposite side thereof; a second flange portion connecting the fourth ridgeline and the second vertical wall on an opposite side thereof; and a curved flange portion connecting the second curved ridgeline and the vertical wall ridgeline on an opposite side thereof and connecting the first flange portion and the second flange portion, wherein a distance from the bottom portion to the curved flange portion in a direction perpendicular to the bottom portion of the corner shape is defined as a corner shape height h, a radius of curvature of the vertical wall ridgeline is defined as Rb, an angle formed between the bottom portion and the first vertical wall is defined as E1, and an angle formed between the bottom portion and the second vertical wall is defined as E2, and 90°≦E2<105° (Formula 9), is formed by press working from a single material metal plate, does not include any joints between material metals, and further satisfies the following, where t is the thickness of the material metal plate, r1 is the radius of curvature of the first ridge line, r2 is the radius of curvature of the second ridge line, r3 is the radius of curvature of the third ridge line, and r4 is the radius of curvature of the fourth ridge line: 2.5t≦r1≦0.2h (Formula 10) 2.5t≦r2≦0.2h (Formula 11) 2.5t≦r3≦0.2h (Formula 12) 2.5t≦r4≦0.2h (Formula 13).

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