Abstract: A formed article having a polygonal tube shape is produced by performing polygonal tube deep drawing on a blank made of a steel sheet, the formed article including a bottom surface part having a polygonal shape, a side wall including a straight side part continuous with a side of the bottom surface part and a vertical ridge connecting ends, in the right-left direction, of adjacent straight side parts, and a flange continuous with the side wall. A side of a flange region to become the flange in the blank includes a notch, and the notch is formed on the side of a part of the flange region, the part being continuous with a region at a position closer to the vertical ridge than a position of a central part in the right-left direction in the straight side part.

Abstract: A method includes two or more reference strain gradient information being a relationship between the strain at the hole edge and a strain gradient along a radial direction. Hole expansion forming is performed on the evaluation metal sheet under the same forming conditions as respective forming conditions corresponding to at least two pieces of the reference strain gradient information to obtain at least two limit hole expansion ratios at a hole expansion limit of the evaluation metal sheet. A formable region of the evaluation metal sheet is obtained from the at least two pieces of the reference strain gradient information and the obtained at least two limit hole expansion ratios at the hole expansion limit. Stretch flange cracking at the sheared end face of the evaluation metal sheet is evaluated by the obtained formable region.

Abstract: To further enhance the evaluation accuracy of a delayed fracture. Focusing on the fact that a calculated stress value serving as the reference for the occurrence of the delayed fracture changes depending on analysis conditions of a forming analysis, a value obtained by changing a stress value serving as the reference for the occurrence of the delayed fracture according to the analysis conditions for analyzing an intended formed article (article for practical use) is used as the reference for evaluating the delayed fracture. For example, analysis conditions of a forming analysis in an evaluation test of the delayed fracture are matched with analysis conditions of a forming analysis of an article for practical use represented by an actual automobile component.

Abstract: A punch and a pad sandwiching a top sheet portion, bending blades for bend-forming the vertical wall portions, and stoppers facing the bending blades are provided. The punch is supported by a first cushion component. The bending blades each have an upper die component and a lower die component disposed facing each other in the press direction with an interval equal to a set compression amount in the range of 2% or more and 6% or less of the heights of the vertical wall portions and a second cushion component interposed between the upper die component and the lower die component, maintaining the interval, and contractible in the press direction. The cushion pressure of the second cushion component is lower than the cushion pressure of the first cushion component and has such cushion pressure that the second cushion component does not contract during the bend-forming of the vertical wall portions.

Abstract: A pressed component manufacturing method wherein, in press forming a metal sheet into a final component shape through two or more press steps, the inflow amount of the required material is determined based on the increase in the cross-sectional line length of the shape with respect to the line length before forming when the metal sheet is press formed by a single press step, the determined amount is distributed to each step, and a preformed shape after press forming based on the distributed inflow amount. As the cross section, a line orthogonal to a direction in which the material flows when the metal sheet is drawn is set, and a plurality of cross sections is set which is individually cut by each of planes orthogonal to the line and extending in a direction along the sheet thickness direction of the metal sheet before forming.

Abstract: A method for producing a pressed component and for designing a die applicable even when a component shape that cannot be formed without being greatly drawn is produced.

Abstract: A shearing work technology of metal sheets, such as high-strength steel sheets, is excellent in stretch flange crack resistance and delayed fracture resistance of the sheared end surface. A metal sheet shearing work method including: applying double shearing work to an end portion of at least one part of the metal sheet; and forming a first area having a cutting margin of a second shearing work of 5 mm or less in first cutting in the double shearing work. Second cutting in the double shearing work is carried out in a state where the movement on an end portion side of the first area is restrained. For example, by providing projection areas continuous to the first area and restraining the projection areas, the movement on the end portion side of the first area is restrained.

Abstract: A material is press formed into a component shape including a top sheet portion including a curved outer peripheral edge portion curved in such a manner as to be recessed inward, a vertical wall portion, and a flange portion. When a lower die and a pad sandwich a sandwiching region that is a region including at least a part of a region corresponding to the top sheet portion, an upper die is moved in a pressing direction to perform bending while moving the sandwiched material to the vertical wall portion side. A surface of the lower die that sandwiches the sandwiching region is provided with one or more ridgelines for forming bends. The ridgelines are set at positions such that, when the bending is complete, the position of the top sheet portion is located on the vertical wall portion side rather than the positions of the ridgelines.

Abstract: A press forming technology capable of reducing forming defects in a formed component having a hat-shaped cross-sectional shape and including a shape curved to protrude toward a flange portion in a side view. The technology includes a first forming step of press forming a metal sheet into an intermediate formed product that includes a wavy shape including uneven shapes continuous along a longitudinal direction in vertical wall portion and flange portion forming positions, an amplitude of the uneven shapes in a sheet thickness direction increasing toward a position corresponding to a boundary between the portions, and a second forming step of performing bending on the intermediate formed product. A longitudinal line length at the position corresponding to the boundary between the portions in the intermediate formed product is set to coincide with or approach a longitudinal line length at the boundary between the portions in the press-formed component shape.

Abstract: To reduce warping of vertical wall portions without causing buckling during pressing. Press-forming into a hat cross-sectional shape having one linear vertical wall portion and the other curved vertical wall portion and not having a flange portion is performed. A punch and a pad sandwiching a top sheet portion therebetween, bending blades for bend-forming the vertical wall portions, and stoppers facing the bending blades are provided. The punch is supported by a first cushion component. The bending blades each have an upper die component and a lower die component disposed facing each other in the press direction with an interval (D) equal to a set compression amount in the range of 2% or more and 6% or less of the heights of the vertical wall portions and a second cushion component interposed between the upper die component and the lower die component, maintaining the interval (D), and contractible in the press direction.

Abstract: A method includes press forming a metal sheet into an intermediate formed product bent out of a plane and forming into a desired press-formed component shape. In a region to be a flange portion, an angle to be bent out of the plane is equal to or less than an angle formed by the flange portion at the curved portion in the press-formed component shape. The projection portion has a largest projection height at the center portion in the longitudinal direction of the region to be the curved portion as seen in the side view, and a longitudinal length of a region to be the top sheet portion is set to coincide with or approach a longitudinal length of the top sheet portion in the press-formed component shape.

Abstract: A technology capable of suppressing end cracking due to a delayed fracture without restrictions on the target pressed component shape. When it is estimated that the end cracking due to the delayed fracture in an end of a material to be pressed is concerned, double cutting processing including performing cutting processing of the end containing at least a place where the end cracking is concerned twice is provided as preprocessing for the press forming causing the concern about the end cracking. The double cutting processing includes performing, in first cutting, cutting to form a partial beam-shaped projection portion at a position containing the place where the end cracking is concerned, and cutting the projection portion in second cutting.

Abstract: A shearing die for preventing damage of a die tool in shearing of a super-high-tension steel sheet and a press-forming method using the same. The shearing die for shearing a metal sheet in a direction intersecting a first-sheared edge of the metal sheet in press-working including a plurality of shearing processes to produce a formed article from the metal sheet by press-forming, in which the shearing die comprises a fitting part that can detach a shearing blade in the vicinity of a region coming in contact with an end of the first-sheared edge.

Abstract: A press formed product is disclosed. A method for manufacturing the press formed product is a method for manufacturing the press formed product including applying press processing including stretch flange forming to a single metal sheet of one sheet material after performing shearing processing of the metal sheet to manufacture the press formed product. When a region where a stretch flange crack is estimated to be likely to occur when the single metal sheet is press formed by the press processing is set as a stretch flange crack region, the press processing is applied after heating and cooling the end surface of the metal sheet positioned in the stretch flange crack region and at least the end surface in the end surface and the vicinity thereof in the single metal sheet after the shearing processing.

Abstract: A pressing technology for reducing tensile residual stress generated on a sheared edge face of a metal sheet after press forming in order to prevent occurrence of a delayed fracture on the sheared edge face. A pressed component manufacturing method for manufacturing a pressed component by press-forming a metal sheet having a sheared edge face includes a first press forming step in which it is estimated that tensile residual stress is generated in a direction along the sheared edge on a portion of the sheared edge face of the metal sheet after die release, in which the method includes, as a subsequent step to the first press forming step, a tensile residual stress relaxation step of bulging, in the sheet thickness direction, a region that includes at least a site on a sheared edge face where it is estimated that the tensile residual stress is generated.

Abstract: A metal sheet for press forming has a shape such that a boundary position between the region corresponding to the curved portion and an other region in the region corresponding to a curved portion is rotationally displaced in-plane around a rotational center set at a position on a curved recessed side rather than a position corresponding to a ridge line between a top sheet portion and a vertical wall portion on the curved recessed side, in a direction in which a line length of an outer edge of a position to be formed into the flange portion on a curved protruding side in the region corresponding to a curved portion approaches a line length of an outer edge of the flange portion on the curved protruding side in the press-formed component shape.

Abstract: Warpage or torsion in a longitudinal direction is suppressed when an elongated curved component is manufactured by press forming. A method for manufacturing a pressed component includes a first step of press forming a metal sheet in a desired component shape using a first die, and a second step of press forming a formed product using a second die after the first step. In the second step, a cross section of a bent part and a vertical wall part are controlled to be opened depending on warpage at longitudinal end portions of the component by elastic recovery due to release from the first die, thereby suppressing the warpage.

Abstract: A method includes two or more reference strain gradient information being a relationship between the strain at the hole edge and a strain gradient along a radial direction. Hole expansion forming is performed on the evaluation metal sheet under the same forming conditions as respective forming conditions corresponding to at least two pieces of the reference strain gradient information to obtain at least two limit hole expansion ratios at a hole expansion limit of the evaluation metal sheet. A formable region of the evaluation metal sheet is obtained from the at least two pieces of the reference strain gradient information and the obtained at least two limit hole expansion ratios at the hole expansion limit. Stretch flange cracking at the sheared end face of the evaluation metal sheet is evaluated by the obtained formable region.

Abstract: A method for manufacturing a press formed product is disclosed. The manufacturing method includes a first step of manufacturing an intermediate component by forming the curved part such that a line length along the longitudinal direction of a curved convex side WA is shorter than a line length in the product shape and a line length along the longitudinal direction of a curved concave side WB is longer than a line length in the product shape; and a second step of forming the intermediate component such that a line length of the curved convex side WA is longer than the line length in the first step and a line length of the curved concave side WB is shorter than the line length in the first step.

Abstract: A method for manufacturing a press-formed product includes a blanking step of blanking from a sheet-shaped material into a shape in which an excess material portion is added to the contour outline of a developed shape of the press-formed product, a first pressing step of folding the excess material portion to form straight sides into an intermediate formed product with a bent flange portion, a second pressing step of performing press forming including bulging in which the bulging portion is provided on the intermediate formed product, and a trimming step of trimming the excess material portion. A blank material includes excess material portion to be folded to form straight sides circumscribed around or spaced apart from a contour outline of a developed shape of the press-formed product, and an intermediate formed product includes excess material portion including a bent flange portion folded to form straight sides.