Molding manufacturing method

Abstract

To provide a technique capable of suppressing generation cracks in a part where a stretch flange is formed in a press molding.SOLUTION: This molding manufacturing method provides a molding by pressing a blank using first and second molds. The blank includes a top plate equivalent part, a vertical wall equivalent part, and an extension part. The manufacturing method comprises pressing the blank by the first and second molds, forming a fold in the extension part, and forming a top plate part, a vertical wall part, and a flange part. The flange part is formed in the extension part, widens in a direction intersecting the vertical wall part from the outer edge of the vertical wall part, and is bent to form the stretch flange. The fold extends at the outer edge of the flange part in a longitudinal direction.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a method for manufacturing a molded article. [Background technology]

[0002] Patent Document 1 describes a method for manufacturing a press-formed product in which a blank is press-formed using a die and a punch to produce a part having a curved portion that is curved in a plan view perpendicular to the top plate. In this manufacturing method, a material flow promoter is used to manufacture the blank so that the blank material flows into the inner periphery of the curved portion, which is the portion where a so-called stretch flange is formed. The material flow promoter has a raised shape in part of the blank, and locally flows the blank material into the inner periphery of the curved portion. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] WO2017 / 006793 publication Summary of the Invention [Problem to be solved by the invention]

[0004] However, with the above-described manufacturing method, the blank material can only flow into the inner periphery of the curved portion when manufacturing a part such as an L-shaped part, where the curved portion is only partial across the entire part. In other words, when manufacturing a part where the majority of the part is curved, such as a part that is curved in a side view perpendicular to the top plate, the material only flows into a portion of the part where the stretch flange is formed, which poses a problem of cracks easily occurring in the part where the stretch flange is formed.

[0005] One aspect of the present disclosure provides a technique for suppressing the occurrence of cracks in a portion of a press-formed product where a stretch flange is formed. [Means for solving the problem]

[0006] One aspect of the present disclosure is a method for manufacturing a molded product, in which a blank is pressed using a first mold and a second mold to obtain a molded product. The blank has a top plate-equivalent portion, a vertical wall-equivalent portion, and an extension portion. The top plate-equivalent portion represents a portion of the molded product that corresponds to the top plate portion. The vertical wall-equivalent portion represents a portion of the molded product that corresponds to the vertical wall portion. In any plane parallel to the blank, the direction from the vertical wall-equivalent portion toward the top plate-equivalent portion is defined as the inside, and the direction from the vertical wall-equivalent portion toward the opposite side of the top plate-equivalent portion is defined as the outside. The extension portion is a region that extends outward from the outer edge of the vertical wall-equivalent portion. The manufacturing method includes: placing the blank between a first mold and a second mold that are spaced apart from each other; and, with the blank placed between the first mold and the second mold, bringing the first mold and the second mold close to each other to press the blank with the first mold and the second mold, thereby forming a top plate portion, a vertical wall portion, and a flange portion while forming a fold in the extension portion. The flange portion is formed on the extension portion, and is a portion that extends from the outer edge of the vertical wall portion in a direction intersecting the vertical wall portion, and is a portion that has a curved shape to form a stretch flange. The fold extends along the length of the outer edge of the flange portion.

[0007] Here, tensile stress occurs in the flange portion, which is a portion curved to form a stretch flange, during the formation process, and cracks may occur. However, according to the above-mentioned configuration, the following actions and effects can be obtained. That is, since the fold extends along the length direction of the outer edge of the flange portion, the fold is also curved like the flange portion. Therefore, the extension portion outside the fold is also a portion where a stretch flange is formed. Tensile stress occurs in this portion, and as a reaction to this, compressive stress occurs near the fold. The generation of compressive stress relieves the tensile stress in the flange portion. Therefore, it is possible to suppress the occurrence of cracks in the portion where the stretch flange is formed.

[0008] In one aspect of the present disclosure, the portion of the extension portion that is outside the fold line may be removed after the flange portion is formed. With this configuration, the unnecessary portion is removed from the molded product, making it easier to perform any processing on the molded product in a subsequent step.

[0009] In one aspect of the present disclosure, the top plate portion may include a recessed portion recessed in the plate thickness direction. With this configuration, a variety of molded products can be manufactured. In one embodiment of the present disclosure, the recessed portion may be formed in the blank before the blank is placed between the spaced apart first and second molds, which allows for the production of a variety of molded products.

[0010] In one aspect of the present disclosure, the molded article may be an automotive part. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1A is a schematic perspective view of a press-formed product, FIG. 1B is a schematic plan view of the press-formed product, and FIG. 1C is a schematic side view of the press-formed product. [Figure 2] FIG. 1A is a schematic perspective view of an intermediate molded product, FIG. 1B is a schematic plan view of the intermediate molded product, and FIG. 1C is a schematic side view of the intermediate molded product. [Figure 3] FIG. 3 is a flowchart showing a method for manufacturing a press-formed product. [Figure 4] FIG. 4A is a cross-sectional view of the blank and its peripheral structure taken along the pressing direction in the intermediate forming step, and FIG. 4B is a cross-sectional view of the blank and its peripheral structure taken along the pressing direction in the forming step. [Figure 5] FIG. 5A is a schematic perspective view of an upper mold, and FIG. 5B is a schematic perspective view of a lower mold. [Figure 6] FIG. 6 is a diagram for explaining the movement of the blank material. [Figure 7] FIG. 7 is a schematic perspective view of another press-formed product. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, exemplary embodiments of the present disclosure will be described with reference to the drawings. [1. Embodiment] [1-1. Press-molded products] The press-formed product 1 shown in FIGS. 1A to 1C is formed by press-forming a blank 10. The press-formed product 1 is used, for example, as a rear floor side member mounted on a vehicle. The manufacturing method of this embodiment is not limited to the press-formed product 1 shown in FIG. 1 and can be used to manufacture press-formed products of various shapes. For example, it can be used to manufacture press-formed products of any shape that have a stretch flange. A stretch flange is a portion of a flange where tensile stress is generated and the material is stretched. For example, a flange with a stretch flange has a shape formed by bending a blank, and the ridge line, which is the bent portion, has a shape that is a concave arc with respect to the blank.

[0013] The blank 10 is made of high-tensile steel, for example, but is not limited to this, and the blank 10 may be made of stainless steel or iron, for example. The press-formed product 1 includes a post top plate portion 2, a post first vertical wall portion 3, a post second vertical wall portion 4, a post first flange portion 5, and a post second flange portion 6.

[0014] The post top plate portion 2 is a plate-like portion that extends in the same plane for the most part except for a small portion. Hereinafter, when describing the press-molded product 1, the plate thickness direction of the post top plate portion 2 will be referred to as the up-down direction. The post top plate portion 2 is curved in the plate thickness direction. More specifically, the post top plate portion 2 is curved so as to be concave downward. The post top plate portion 2 is also curved when viewed from above. More specifically, the post top plate portion 2 is curved so that the side of the post first vertical wall portion 3 is concave toward the side of the post second vertical wall portion 4.

[0015] The post top plate portion 2 has a first lower recess 21b, a second upper recess 22a, and a second lower recess 22b. The second upper recess 22a is a portion that is recessed upward in the post top plate portion 2 when the post top plate portion 2 is viewed from below. The first lower recess 21b and the second lower recess 22b are portions that are recessed downward in the post top plate portion 2 when the post top plate portion 2 is viewed from above. The positions at which the first lower recess 21b, the second upper recess 22a, and the second lower recess 22b are provided are not particularly limited as long as they are on the post top plate portion 2.

[0016] The post first vertical wall portion 3 is a plate-shaped portion extending from one end of the post top plate portion 2 in a direction intersecting with the post top plate portion 2. In this embodiment, the post first vertical wall portion 3 extends substantially downward from the end of the post top plate portion 2. The portion where the post top plate portion 2 and the post first vertical wall portion 3 are connected forms a first ridge line 3a. The first ridge line 3a is a concave arc that is recessed downward and is an L-shaped curved arc in plan view. The post first vertical wall portion 3 is curved along the first ridge line 3a.

[0017] The post second vertical wall portion 4 is a plate-shaped portion that extends from the end of the post top plate portion 2 opposite the end where the post first vertical wall portion 3 extends, in a direction that intersects with the post top plate portion 2. In this embodiment, the post second vertical wall portion 4 extends approximately downward from the end of the post top plate portion 2. The portion where the post top plate portion 2 and the post second vertical wall portion 4 are connected forms a second ridge line 3b. The second ridge line 3b is a concave arc that is recessed downward. The post second vertical wall portion 4 is curved along the second ridge line 3b.

[0018] The post first flange portion 5 is a plate-shaped portion that extends from the end of the post first vertical wall portion 3 opposite the first ridge line 3a in a direction intersecting with the post first vertical wall portion 3. The post first flange portion 5 extends in the opposite direction from the direction in which the post top plate portion 2 extends relative to the post first vertical wall portion 3. The portion where the post first vertical wall portion 3 and the post first flange portion 5 are connected forms a third ridge line 4a. The third ridge line 4a is a concave arc shape that is recessed downward and is an L-shaped curved arc shape in a plan view. The post first flange portion 5 is curved along the third ridge line 4a. In other words, the post first flange portion 5 is bent in the plate thickness direction and forms an extension flange with a curved shape in a plan view. The post first flange portion 5 is approximately parallel to the post top plate portion 2.

[0019] The post second flange portion 6 is a plate-shaped portion that extends from the end of the post second vertical wall portion 4 opposite the second ridge line 3b in a direction intersecting with the post second vertical wall portion 4. The post second flange portion 6 extends in the opposite direction to the direction in which the post top plate portion 2 extends relative to the post second vertical wall portion 4. The portion where the post second vertical wall portion 4 and the post second flange portion 6 are connected forms the fourth ridge line 4b. The fourth ridge line 4b is a concave arc shape that is recessed downward. The post second flange portion 6 is curved along the fourth ridge line 4b. The post second flange portion 6 is approximately parallel to the post top plate portion 2.

[0020] In other words, the press-formed product 1 has a substantially U-shape and is curved downward as a whole as shown in Fig. 1C. In addition, the press-formed product 1 has a portion that is curved in an L-shape in a plan view.

[0021] [1-2. Intermediate molded product] 2A to 2C includes a pre-top plate portion 2A, a pre-first vertical wall portion 3A, a pre-second vertical wall portion 4A, a pre-first flange portion 5A, a pre-second flange portion 6A, and an excess pad portion 7A. The press-formed product 1 is a molded product obtained by processing the intermediate molded product 1A through a trimming process and a molding process, which will be described in detail later. The pre-top plate portion 2A, pre-first vertical wall portion 3A, pre-second vertical wall portion 4A, pre-first flange portion 5A, and pre-second flange portion 6A of the intermediate molded product 1A correspond to the post top plate portion 2, post first vertical wall portion 3, post second vertical wall portion 4, post first flange portion 5, and post second flange portion 6 of the press-formed product 1, respectively. In addition, the fifth ridge line 3Aa formed by the pre-top plate portion 2A and the pre-first vertical wall portion 3A, the sixth ridge line 3Ab formed by the pre-top plate portion 2A and the pre-second vertical wall portion 4A, the seventh ridge line 4Aa formed by the pre-first vertical wall portion 3A and the pre-first flange portion 5A, and the eighth ridge line 4Ab formed by the pre-second vertical wall portion 4A and the pre-second flange portion 6A correspond to the first ridge line 3a, the second ridge line 3b, the third ridge line 4a, and the fourth ridge line 4b of the press-molded product 1, respectively.

[0022] The pre-top plate portion 2A, pre-first vertical wall portion 3A, pre-second vertical wall portion 4A, pre-first flange portion 5A, and pre-second flange portion 6A of the intermediate molded product 1A have substantially the same configurations as the post top plate portion 2, post first vertical wall portion 3, post second vertical wall portion 4, post first flange portion 5, and post second flange portion 6 of the press-molded product 1, respectively. The intermediate molded product 1A also has a substantially U-shaped configuration and is curved downward as a whole, as shown in FIG. 2C. The intermediate molded product 1A also has a portion that is curved in an L-shape in a plan view.

[0023] Similar to the post top plate portion 2, the pre-top plate portion 2A has a first lower recess 21b, a second upper recess 22a, and a second lower recess 22b. The differences between the intermediate product 1A and the press-formed product 1 will be described below.

[0024] The excess pad portion 7A is formed in the intermediate molded product 1A, but is removed when the intermediate molded product 1A is processed into the press-molded product 1, and is therefore not present in the press-molded product 1. The excess pad portion 7A is a plate-shaped portion extending from the end of the pre-first flange portion 5A opposite the seventh ridge line 4Aa. The end of the pre-first flange portion 5A opposite the seventh ridge line 4Aa corresponds to the trim line 50 indicated by the dashed line. The trim line 50 is the outer edge of the pre-first flange portion 5A and indicates a position that serves as a guide when cutting the intermediate molded product 1A in the trimming process described in detail below. The excess pad portion 7A has a fold line 8A formed therein that extends along the length of the outer edge of the pre-first flange portion 5A. In other words, the fold line 8A extends along the length of the trim line 50. In other words, the fold line 8A extends along the pre-first flange portion 5A where the stretch flange is to be formed. The fold 8A is formed to form a mountain fold. In this embodiment, the fold 8A extends to a position approximately equidistant from the pre-first vertical wall portion 3A and forms a ridge line along the seventh ridge line 4Aa. The excess pad portion 7A extends from the end of the pre-first flange portion 5A to the fold line 8A in a curved shape that is approximately the same as that of the pre-first flange portion 5A, and extends at an inclined downward direction from the fold line 8A. In other words, the fold line 8A is formed outside the pre-first flange portion 5A and the trim line 50. The fold line 8A has a concave arc shape that is concave downward and is curved in an L-shape in a plan view. The fold line 8A may also be a gentle ridge line, as long as the fold line 8A is formed in a shape that is suitable for the material of the blank 10.

[0025] Furthermore, the fifth ridge line 3Aa, the sixth ridge line 3Ab, the seventh ridge line 4Aa, and the eighth ridge line 4Ab of the intermediate molded product 1A are formed slightly more gently than the first ridge line 3a, the second ridge line 3b, the third ridge line 4a, and the fourth ridge line 4b of the press-molded product 1. The press-molded product 1 is formed slightly larger in the vertical direction than the intermediate molded product 1A.

[0026] [1-3. Manufacturing methods for press-molded products] As shown in FIG. 3, the method for manufacturing the press-formed product 1 includes an intermediate forming step, a trimming step, and a forming step.

[0027] [1-3-1. Intermediate forming process] The intermediate forming step S10 is a step for press-forming the blank 10 to form an intermediate formed product 1A. As shown in Fig. 4A, the blank 10 used in this manufacturing method includes a top plate equivalent portion 2B, a first vertical wall equivalent portion 3B, a second vertical wall equivalent portion 4B, and an extension portion 9B.

[0028] The top plate-equivalent portion 2B represents a portion corresponding to the pre-top plate portion 2A of the intermediate molded product 1A. In other words, the top plate-equivalent portion 2B is an area of ​​the blank 10 where the pre-top plate portion 2A will be formed when the intermediate molded product 1A is formed.

[0029] The first vertical wall equivalent portion 3B represents a portion corresponding to the pre-first vertical wall portion 3A of the intermediate molded product 1A. In other words, the first vertical wall equivalent portion 3B is an area of ​​the blank 10 where the pre-first vertical wall portion 3A will be formed when the intermediate molded product 1A is formed.

[0030] The second vertical wall equivalent portion 4B represents a portion corresponding to the pre-second vertical wall portion 4A of the intermediate molded product 1A. In other words, the second vertical wall equivalent portion 4B is an area of ​​the blank 10 where the pre-second vertical wall portion 4A will be formed when the intermediate molded product 1A is formed.

[0031] In this embodiment, a first vertical wall equivalent portion 3B and a second vertical wall equivalent portion 4B extend on both sides of the top plate equivalent portion 2B in the blank 10. Hereinafter, in any plane parallel to the blank 10, the direction from the first vertical wall equivalent portion 3B and the second vertical wall equivalent portion 4B toward the top plate equivalent portion 2B will be referred to as the inside, and the direction from the first vertical wall equivalent portion 3B and the second vertical wall equivalent portion 4B toward the opposite side of the top plate equivalent portion 2B will be referred to as the outside.

[0032] The extension portion 9B is a region that extends further outward from the outer edge of the first vertical wall equivalent portion 3B. In the intermediate molding step S10, a press molding device including an upper mold 61, an upper pad 62, a gas cushion 63, and a lower mold 71 is used.

[0033] The upper mold 61 shown in Figures 4A and 5A is a mold for press molding. The upper mold 61 includes a top surface 61a, an upper first wall forming portion 61b, an upper second wall forming portion 61c, an upper first flange forming portion 61d, an upper second flange forming portion 61e, and an upper fold forming portion 61f. Note that Figure 5A schematically illustrates only the shape of the lower surface of the upper mold 61, and the top surface 61a is omitted.

[0034] The top surface 61a is a surface of the upper mold 61 facing downward, and extends in a direction perpendicular to the up-down direction. The lower mold 71 shown in Figures 4A and 5B is also a mold for press molding. The lower mold 71 has a lower top plate forming portion 71a, a lower first wall forming portion 71b, a lower second wall forming portion 71c, a lower first flange forming portion 71d, a lower second flange forming portion 71e, and a lower fold forming portion 71f. Note that Figure 5B schematically illustrates only the shape of the upper surface of the lower mold 71, and omits recesses and other features provided in the lower top plate forming portion 71a.

[0035] The lower top plate forming portion 71a is a portion for forming the pre-top plate portion 2A. The upper surface of the lower top plate forming portion 71a is provided with recesses corresponding to the first lower recess 21b, the second upper recess 22a, and the second lower recess 22b. The lower top plate forming portion 71a is curved so as to be recessed downward.

[0036] The upper first wall forming portion 61b and the lower first wall forming portion 71b have shapes that imitate the pre-first vertical wall portion 3A of the intermediate molded product 1A and are portions for forming the pre-first vertical wall portion 3A. The upper second wall forming portion 61c and the lower second wall forming portion 71c have shapes that imitate the pre-second vertical wall portion 4A of the intermediate molded product 1A and are portions for forming the pre-second vertical wall portion 4A.

[0037] The upper first flange forming portion 61d and the lower first flange forming portion 71d have shapes following the pre-first flange portion 5A of the intermediate molded product 1A and are portions for forming the pre-first flange portion 5A. The upper second flange forming portion 61e and the lower second flange forming portion 71e have shapes following the pre-second flange portion 6A of the intermediate molded product 1A and are portions for forming the pre-second flange portion 6A.

[0038] The upper fold forming portion 61f is a portion for forming the excess pad portion 7A. The upper fold forming portion 61f is a portion that spreads from the end of the upper first flange forming portion 61d. A fold 61g is formed in the upper fold forming portion 61f, extending along the length direction of the outer edge of the upper first flange forming portion 61d. In other words, the fold 61g extends along the upper first flange forming portion 61d for forming the pre-first flange portion 5A where the stretch flange will be formed. The fold 61g is formed to form a valley fold. The upper fold forming portion 61f spreads on approximately the same curved surface as the upper first flange forming portion 61d from the end of the upper first flange forming portion 61d to the fold 61g, and spreads downward at an inclination with the fold 61g as a boundary. In other words, the fold 61g is formed outside the upper first flange forming portion 61d. The angle formed by the upper first flange forming portion 61d and the upper fold forming portion 61f is substantially the same as the angle formed by the pre-first flange portion 5A and the excess material portion 7A in the intermediate molded product 1A.

[0039] The lower fold forming portion 71f is also a portion for forming the excess pad portion 7A. The lower fold forming portion 71f is a portion that spreads from the end of the lower first flange forming portion 71d. The lower fold forming portion 71f has a fold 71g formed therein, extending along the length direction of the outer edge of the lower first flange forming portion 71d. In other words, the fold 71g extends along the lower first flange forming portion 71d for forming the pre-first flange portion 5A where the stretch flange will be formed. The fold 71g is formed to form a mountain fold. The lower fold forming portion 71f spreads along substantially the same curved surface as the lower first flange forming portion 71d from the end of the lower first flange forming portion 71d to the fold 71g, and spreads downward at an inclination from the fold 71g. In other words, the fold 71g is formed outside the lower first flange forming portion 71d. The angle formed by the lower first flange forming portion 71d and the lower fold forming portion 71f is substantially the same as the angle formed by the pre-first flange portion 5A and the excess material portion 7A in the intermediate molded product 1A.

[0040] The upper pad 62 is a pad for press molding. In this embodiment, the cross section of the upper pad 62 in the vertical direction is substantially rectangular. The lower surface of the upper pad 62 is provided with recesses corresponding to the first lower recess 21b, the second upper recess 22a, and the second lower recess 22b.

[0041] The gas cushion 63 is a cushion that utilizes the reaction force of compressed gas. The gas cushion 63 expands and contracts in the vertical direction due to pressure. The upper surface of the gas cushion 63 abuts against the lower surface of the top surface 61 a. The lower surface of the gas cushion 63 abuts against the upper surface of the upper pad 62.

[0042] Although not shown in the figure, the blank 10 is placed between an upper mold 61 and a lower mold 71 that are spaced apart. Specifically, the blank 10 is placed between an upper pad 62 that is placed above the blank 10 and below the upper mold 61, and a lower mold 71 that is placed below the blank 10. At this time, the upper first wall forming portion 61b, the upper second wall forming portion 61c, the upper first flange forming portion 61d, the upper second flange forming portion 61e, and the upper fold forming portion 61f of the upper mold 61 are approximately parallel to the lower first wall forming portion 71b, the lower second wall forming portion 71c, the lower first flange forming portion 71d, the lower second flange forming portion 71e, and the lower fold forming portion 71f of the lower mold 71, respectively.

[0043] The upper pad 62 abuts against the upper surface of the blank 10. The lower top plate forming portion 71a of the lower mold 71 abuts against the lower surface of the blank 10. The blank 10 is clamped from above and below by the upper pad 62 and the lower mold 71. Specifically, the top plate equivalent portion 2B of the blank 10 is clamped between the upper pad 62 and the lower mold 71. The clamped blank 10 is in a state in which the first vertical wall equivalent portion 3B, the second vertical wall equivalent portion 4B, and the extension portion 9B are floating.

[0044] The blank 10 is sandwiched between the upper pad 62 and the lower die 71, and the upper die 61 is moved downward from above the upper pad 62, thereby performing press forming. As shown in FIG. 4A, when the upper mold 61 and the lower mold 71 are brought close to each other, first, the first lower recess 21b, the second upper recess 22a, and the second lower recess 22b are formed in the top plate equivalent portion 2B.

[0045] Next, the upper crease forming portion 61f comes into contact with the blank 10. Specifically, the upper crease forming portion 61f comes into contact with the extending portion 9B. The extending portion 9B extends in a direction substantially perpendicular to the sheet thickness, while the upper crease forming portion 61f is inclined downward. Therefore, as the upper mold 61 approaches the lower mold 71, the contact area between the extending portion 9B and the upper crease forming portion 61f increases. As the extending portion 9B bends downward, the fold 8A is formed in the extending portion 9B.

[0046] When the upper mold 61 is brought closer to the lower mold 71 and the blank 10 is pressed, the blank 10 is deformed so that the upper first wall forming portion 61b, the upper second wall forming portion 61c, the upper first flange forming portion 61d, the upper second flange forming portion 61e, and the upper fold forming portion 61f abut against each other. This forms a pre-top plate portion 2A, a pre-first vertical wall portion 3A, a pre-second vertical wall portion 4A, a pre-first flange portion 5A, a pre-second flange portion 6A, and an excess pad portion 7A in the blank 10. More specifically, the pre-top plate portion 2A is formed in the top plate-equivalent portion 2B, the pre-first vertical wall portion 3A is formed in the first vertical wall-equivalent portion 3B, and the pre-second vertical wall portion 4A is formed in the second vertical wall-equivalent portion 4B. Furthermore, the pre-first flange portion 5A and the excess pad portion 7A are formed in the extension portion 9B.

[0047] [1-3-2. Trim process] The trimming step S20 is a step for performing trimming on the intermediate molded product 1A formed in the intermediate molding step S10. In the trimming step, the intermediate molded product 1A is cut along a trim line 50. The trim line 50 is the outer edge of the pre-first flange portion 5A. In other words, the trim line 50 is the boundary between the pre-first flange portion 5A and the excess material portion 7A. In other words, in the trimming step, the excess material portion 7A is removed from the intermediate molded product 1A.

[0048] [1-3-3. Molding process] The molding step S30 is a step for performing press working on the molded product 1B from which the excess metal portion 7A has been removed in the trimming step S20.

[0049] In the molding step, as shown in FIG. 4B, an upper mold 61B and a lower mold 71B different from the upper mold 61 and the lower mold 71 are used to perform any processing on the molded product 1B, thereby forming the press-molded product 1.

[0050] [1-4. Effect] In the region where the stretch flange is formed, tensile stress occurs during the forming process, and the material is stretched. As the material is stretched, cracks may occur in the region where the stretch flange is formed. Furthermore, as the material is stretched, the region where the stretch flange is formed may become thinner than the original thickness of the blank.

[0051] Since the pre-first flange portion 5A is curved and concave downward, the pre-first flange portion 5A is a region where a stretch flange is formed, and therefore, the pre-first flange portion 5A is a region where tensile stress is generated.

[0052] Here, the fold 8A has a concave arc shape that is concave downward. Therefore, the excess material portion 7A is also a region where a stretch flange is formed. Because tensile stress occurs in the region where a stretch flange is formed, tensile stress occurs in the excess material portion 7A. In particular, tensile stress occurs in the portion of the excess material portion 7A outside the fold 8A. In Figure 6, to explain the tensile stress occurring in the excess material portion 7A, the direction of the tensile stress is simplified and indicated by arrow A. When tensile stress occurs, compressive stress occurs around it as a reaction. In other words, compressive stress occurs near the fold 8A. In Figure 6, to explain the compressive stress occurring near the fold 8A, the direction of the compressive stress is simplified and indicated by arrow B. The generation of compressive stress relieves the tensile stress in the pre-first flange portion 5A. Furthermore, the generation of compressive stress near the fold 8A causes the material of the blank of the excess material portion 7A to flow into the pre-first flange portion 5A, reducing the reduction in plate thickness.

[0053] In other words, in this embodiment, the pre-first flange portion 5A and the excess pad portion 7A are formed while the fold line 8A is being formed, thereby intentionally generating tensile stress in the excess pad portion 7A. As a result, compressive stress is generated near the fold line 8A, which is thought to alleviate the tensile stress in the pre-first flange portion 5A.

[0054] [1-5.Effects] According to the embodiment described above in detail, the following effects can be obtained.

[0055] (1a) In the above embodiment, the blank 10 is pressed by the upper mold 61 and the lower mold 71, forming a fold 8A in the extension portion 9B, while forming the pre-top plate portion 2A, pre-first vertical wall portion 3A, pre-second vertical wall portion 4A, pre-first flange portion 5A, pre-second flange portion 6A, and excess material portion 7A in the blank 10. The fold 8A extends along the length of the outer edge of the pre-first flange portion 5A and has a concave arc shape recessed downward. With this configuration, as described in detail in [1-4. Action], the tensile stress in the pre-first flange portion 5A is alleviated. Therefore, the occurrence of cracks in the portion where the stretch flange is formed can be suppressed. Furthermore, the reduction in the sheet thickness in the portion where the stretch flange is formed is also reduced.

[0056] (1b) In the above embodiment, the post first flange portion 5 has a stretch flange formed in a shape that is bent in the plate thickness direction and curved in a plan view. With this configuration, a flange portion with higher strength can be formed compared to a flange portion without stretch flange.

[0057] (1c) In the above embodiment, the first lower recess 21b, the second upper recess 22a, and the second lower recess 22b are formed by the upper pad 62 and the lower mold 71. With this configuration, the pre-first flange portion 5A and each recess can be formed in the same process.

[0058] (1d) In the above embodiment, in the intermediate forming step S10, the pre-top plate portion 2A, the pre-first vertical wall portion 3A, the pre-second vertical wall portion 4A, the pre-first flange portion 5A, the pre-second flange portion 6A, and the excess material portion 7A are formed on the blank 10. With this configuration, all of the portions of the intermediate formed product 1A can be formed in the same step.

[0059] (1e) In the above embodiment, in the trimming step S20, excess material 7A is removed from intermediate molded product 1A to form molded product 1B. That is, the portion of extension 9B outside fold 8A is removed after pre-first flange 5A is formed. With this configuration, unnecessary portions are removed from intermediate molded product 1A, making it easier to apply any processing to molded product 1B in the subsequent molding step S30.

[0060] [1-6. Correspondence] In the above embodiment, the upper mold 61 corresponds to the first mold, and the lower mold 71 corresponds to the second mold. The intermediate molded product 1A corresponds to the molded product, the pre-top plate portion 2A corresponds to the top plate portion, the pre-first vertical wall portion 3A corresponds to the vertical wall portion, the pre-first flange portion 5A corresponds to the flange portion, and the fold 8A corresponds to the fold. The first lower recess 21b, the second upper recess 22a, and the second lower recess 22b correspond to the recessed portions.

[0061] 3. Other Embodiments Although the embodiments of the present disclosure have been described above, it goes without saying that the present disclosure is not limited to the above-described embodiments and can take on various forms.

[0062] (3a) In the above embodiment, the pre-first flange portion 5A has a stretch flange formed in a shape that is bent in the plate thickness direction and curved in a plan view. However, the shape of the portion where the stretch flange is formed is not limited to this. For example, the stretch flange may be formed in a shape that is bent in the plate thickness direction, or may be formed in a curved shape in a plan view. More specifically, as shown in FIG. 7, the above manufacturing method can also be used when forming a press-formed product 100 that is not curved in a plan view but is concave in the plate thickness direction.

[0063] Furthermore, the above manufacturing method can also be used when forming a press-molded product that is curved in a T-shape or Y-shape in plan view. When manufacturing an intermediate molded product having multiple curved portions, the intermediate molded product may be formed while forming multiple folds corresponding to the multiple curved portions. When forming the intermediate molded product of the press-formed product 100 shown in FIG. 7, in addition to the fold 8A extending along the length of the outer edge of the pre-first flange portion 5A, another fold extending along the length of the outer edge of the pre-second flange portion 6A may be formed while forming the intermediate molded product. By manufacturing the intermediate molded product in this manner, it is possible to alleviate the tensile stress generated in the pre-first flange portion 5A and also to alleviate the tensile stress generated in the pre-second flange portion 6A. In other words, even for an intermediate molded product having multiple curved portions, the curved portions can be formed simultaneously to alleviate the tensile stress in each of the multiple curved portions, thereby suppressing the occurrence of cracks in each portion.

[0064] (3b) In the above embodiment, one fold 8A extending along the length of the outer edge of the pre-first flange portion 5A is formed in the excess pad portion 7A. However, the number of folds formed in the excess pad portion 7A is not limited to this. The number of folds formed in the excess pad portion 7A may be two or more. For example, a second fold parallel to the fold 8A may be formed in the excess pad portion 7A on the side opposite the outer edge of the pre-first flange portion 5A across the fold 8A. In other words, the second fold may be formed so that the outer edge of the pre-first flange portion 5A, the fold 8A, and the parallel second fold are aligned in this order. The angle of downward inclination from the second fold may be steeper than the angle of downward inclination from the fold 8A. Conversely, the angle of downward inclination from the second fold may be gentler than the angle of downward inclination from the fold 8A. The inclined surface from the outer edge of the pre-first flange portion 5A to the fold line 8A and the surface that slopes downward at the second fold line may be substantially parallel. In other words, the fold line 8A and the second fold line form two folds in the excess pad portion 7A, thereby forming a step in the excess pad portion 7A. The step may be formed as a plurality of steps in a staircase pattern.

[0065] Furthermore, the fold 8A does not have to be formed as a continuous line, and the fold may be partially broken in the extending direction. (3c) In the above embodiment, the fold 8A is formed as a mountain fold. However, the shape of the fold is not limited to this. The fold may be formed as a valley fold. In other words, the excess pad portion 7A may extend from the end of the pre-first flange portion 5A to the fold 8A in a curved shape that is substantially the same as that of the pre-first flange portion 5A, and may extend at an angle upward from the fold 8A.

[0066] (3d) In the above embodiment, the first lower recess 21b, the second upper recess 22a, and the second lower recess 22b are formed in the top plate equivalent portion 2B by the upper pad 62 and the lower mold 71. However, the first lower recess 21b, the second upper recess 22a, and the second lower recess 22b may be formed in the blank 10 in advance before the blank 10 is placed between the upper mold 61 and the lower mold 71.

[0067] (3e) The function of one component in the above embodiments may be distributed among multiple components, or the functions of multiple components may be integrated into one component. Also, part of the configuration of the above embodiments may be omitted. Furthermore, at least part of the configuration of the above embodiments may be added to or substituted for the configuration of another of the above embodiments.

[0068] [Technical idea disclosed in this specification] [Item 1] A method for manufacturing a molded product by pressing a blank using a first mold and a second mold to obtain a molded product, The blank has a top plate equivalent portion representing a portion corresponding to a top plate portion of a molded product, a vertical wall equivalent portion representing a portion corresponding to a vertical wall portion of the molded product, and an extension portion, In any plane parallel to the blank, the direction from the vertical wall equivalent portion toward the top plate equivalent portion is defined as the inside, and the direction from the vertical wall equivalent portion toward the opposite side of the top plate equivalent portion is defined as the outside, the extension portion is a region that extends outward from the outer edge of the vertical wall portion, The manufacturing method includes: placing the blank between the first and second spaced apart molds; With the blank disposed between the first mold and the second mold, the first mold and the second mold are brought close to each other, thereby pressing the blank with the first mold and the second mold, and forming the top plate portion, the vertical wall portion, and the flange portion while forming a fold in the extension portion; Including, The flange portion is formed on the extension portion and extends from the outer edge of the vertical wall portion in a direction intersecting the vertical wall portion, and is a portion having a curved shape so as to form a stretch flange, A method for manufacturing a molded product, wherein the fold extends along the length of the outer edge of the flange portion.

[0069] [Item 2] A method for producing a molded article according to item 1, A method for manufacturing a molded product, comprising removing a portion of the extension portion outside the fold after the flange portion is formed.

[0070] [Item 3] A method for producing a molded article according to item 1 or 2, A method for manufacturing a molded product, wherein the top plate portion has a recessed portion recessed in the plate thickness direction.

[0071] [Item 4] Item 3. A method for producing a molded article according to item 3, A method for manufacturing a molded product, wherein the recessed portion is formed in the blank before the blank is placed between the separated first mold and second mold.

[0072] [Item 5] A method for producing a molded article according to any one of items 1 to 4, The method for manufacturing a molded product, wherein the molded product is an automobile part. [Explanation of symbols]

[0073] 1,100...press-molded product, 1A...intermediate molded product, 1B...molded product, 2...post top plate portion, 2A...pre-top plate portion, 2B...top plate equivalent portion, 3...post first vertical wall portion, 3A...pre-first vertical wall portion, 3B...first vertical wall equivalent portion, 4...post second vertical wall portion, 4A...pre-second vertical wall portion, 4B...second vertical wall equivalent portion, 5...post first flange portion, 5A...pre-first flange portion, 6...post second flange portion, 6A...pre-second flange portion, 7A...excess material portion, 8A, 61g, 71g...fold, 9B...extension portion, 3a...first ridge line, 3b...second ridge line, 4a...third ridge line, 4b...fourth ridge line, 3Aa...fifth ridge line, 3Ab...sixth ridge line, 4Aa...seventh ridge line, 4Ab...8th ridge line, 10...blank, 21b...first lower recess, 22a...second upper recess, 22b...second lower recess, 50...trim line, 61, 61B...upper mold, 61a...top surface, 61b...upper first wall forming portion, 61c...upper second wall forming portion, 61d...upper first flange forming portion, 61e...upper second flange forming portion, 61f...upper fold forming portion, 62...upper pad, 63...gas cushion, 71, 71B...lower mold, 71a...lower top plate forming portion, 71b...lower first wall forming portion, 71c...lower second wall forming portion, 71d...lower first flange forming portion, 71e...lower second flange forming portion, 71f...lower fold forming portion.

Claims

1. A method for manufacturing a molded product by pressing a blank using a first mold and a second mold to obtain a molded product, The blank has a top plate equivalent portion representing a portion corresponding to a top plate portion of a molded product, a vertical wall equivalent portion representing a portion corresponding to a vertical wall portion of the molded product, and an extension portion, In any plane parallel to the blank, the direction from the vertical wall equivalent portion toward the top plate equivalent portion is defined as the inside, and the direction from the vertical wall equivalent portion toward the opposite side of the top plate equivalent portion is defined as the outside, the extension portion is a region that extends outward from the outer edge of the vertical wall portion, The manufacturing method includes: placing the blank between the first and second spaced apart dies; With the blank disposed between the first mold and the second mold, the first mold and the second mold are brought close to each other, thereby pressing the blank with the first mold and the second mold, and forming the top plate portion, the vertical wall portion, and the flange portion while forming a fold in the extension portion; Including, The flange portion is formed on the extension portion and extends from the outer edge of the vertical wall portion in a direction intersecting the vertical wall portion, and is a portion having a curved shape so as to form a stretch flange, A method for manufacturing a molded product, wherein the fold extends along the length of the outer edge of the flange portion.

2. A method for producing the molded article according to claim 1, A method for manufacturing a molded product, comprising removing a portion of the extension portion outside the fold after the flange portion is formed.

3. A method for producing the molded article according to claim 1 or claim 2, A method for manufacturing a molded product, wherein the top plate portion has a recessed portion recessed in the plate thickness direction.

4. A method for producing the molded article according to claim 3, A method for manufacturing a molded product, wherein the recessed portion is formed in the blank before the blank is placed between the separated first mold and second mold.

5. A method for producing the molded article according to claim 1 or claim 2, The method for manufacturing a molded product, wherein the molded product is an automobile part.

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