Abstract: A press forming method includes: moving a die toward a punch; bringing a punch side and a die side elastic bodies into contact with a metal sheet; and press forming the metal sheet, wherein an amount of protrusion of the punch side elastic body is set so that the punch side elastic body: comes into contact with the metal sheet before the punch; and becomes flush at a bottom dead center, and an amount of protrusion of the die side elastic body is set so that: the die side elastic body comes into contact with the metal sheet before the punch; and a product of: a load of the die side elastic body; and a friction coefficient between the die side elastic body and the metal sheet, becomes equal to or larger than an absolute value of a difference between tensions acting on the portions sandwiching a character-line equivalent portion.

Abstract: A press forming method for an automotive outer panel according to the present invention is a method for press forming a metal sheet 51 into an automotive outer panel 61 having a character line 63 and panel surface portions 65a and 65b by using a punch 3, a die 5, and a blank holder 7. The press forming method includes: a step of providing an elastic body 9 protruding toward the punch 3 side on a die-side forming surface portion 5b forming the panel surface portion 65a, and bringing the elastic body 9 into contact with the metal sheet 51 prior to the die 5; and a step of press forming while crushing the elastic body 9 and pressing the metal sheet 51, and the elastic body 9 is caused to protrude from the die-side forming surface portion 5b so that a frictional force of the crushed elastic body 9 and the metal sheet 51 is equal to or greater than an absolute value of a difference between tensions acting on both sides of a portion 53 corresponding to the character line 63.

Abstract: A press forming method for an automotive outer panel according to the present invention is a method for press forming a metal sheet 51 into an automotive outer panel 61 having a character line 63 and panel surface portions 65a and 65b by using a punch 3, a die 5, and a blank holder 7. The press forming method includes: a step of providing an elastic body 9 protruding toward the punch 3 side on a die-side forming surface portion 5b forming the panel surface portion 65a, and bringing the elastic body 9 into contact with the metal sheet 51 prior to the die 5; and a step of press forming while crushing the elastic body 9 and pressing the metal sheet 51, and the elastic body 9 is caused to protrude from the die-side forming surface portion 5b so that a frictional force of the crushed elastic body 9 and the metal sheet 51 is equal to or greater than an absolute value of a difference between tensions acting on. both sides of a portion 53 corresponding to the character line 63.

Abstract: A method for press forming an automotive outer panel includes: providing an elastic body to a punch such that the elastic body abuts against a metal sheet away from a portion corresponding to a character line in the metal sheet; abutting a contact surface portion of the protruding elastic body against the metal sheet; and forming the character line with the ridgeline and the valley line by relatively moving the die toward the punch while abutting the contact surface portion against the metal sheet to deform the elastic body such that the elastic body becomes flush with the punch-side forming surface portion at a bottom dead center of forming. A protrusion amount of the elastic body from the punch-side forming surface portion is set such that the elastic body contacts the metal sheet before the ridgeline contacts the metal sheet to cause the metal sheet to become plastically deformed.

Abstract: A press forming tool includes: a punch; and a die, and press forms a press forming product including a punch bottom and a shallow concave portion or a low convex portion in the punch bottom. The punch includes a punch bottom forming surface, a concave shape forming portion or a convex shape forming portion, and a low Young's modulus member installation region formed under the punch bottom forming surface and accommodating a low Young's modulus member having a lower Young's modulus than that of the punch bottom forming surface. The low Young's modulus member installation region includes an area directly under the concave shape forming portion or the convex shape forming portion of the punch and has a projected area in a press forming direction that is 110% or greater as large as a projected area of the concave shape forming portion or the convex shape forming portion.

Abstract: Provided is a method for forming a blank, the method being capable of improving both yields and formability. The method for forming a blank 1 includes forming the blank 1 into a preforming shape by plastic deformation and then plastically deforming the blank 1 from the preforming shape into a final shape. The preforming shape is determined so that, in each of cross sections in the final shape, the ratio (L1/L0) of a cross-sectional line length L1 in the preforming shape to a cross-sectional line length L0 in the final shape in the same cross section position falls within a predetermined tolerance range.

Abstract: There is provided a method of manufacturing a curved channel part having a curved portion in a vertical wall portion by press forming, the method restricting stretch flange deformation, which occurs in the vertical wall portion and a flange portion. The method includes a shear deformation step as a step of forming the vertical wall portion. In the shear deformation step, a boundary-side portion of a base section of a blank with respect to a deformation section, and an outer portion of the deformation section are individually restrained, a portion to be a vertical wall portion of the deformation section is shear-deformed in a sheet face, and a material is caused to flow from a portion separated from a curved portion toward the curved portion in an outer edge portion of the portion to be the vertical wall portion.

Abstract: A method of producing a polygonal closed cross-section structural component includes press-forming a metal sheet into a gutter-shaped pre-processed part with a curved form along its longitudinal direction having plural ridge lines corresponding to corner portions of the polygonal closed cross-section in a cross-sectional form developed by cutting the component at a position corresponding to the ridge line located at the innermost side in the radial direction to provide a flange portion extending along the ridge line at the resulting respective ends, and press-forming the pre-processed part to deform inwardly in the cross-sectional direction at a position of one or more of the plural ridge lines to butt the ridge lines located at the innermost side and the flange portions to each other.

Abstract: A method of producing a polygonal closed cross-section structural component includes press-forming a metal sheet into a gutter-shaped pre-processed part with a curved form along its longitudinal direction having plural ridge lines corresponding to corner portions of the polygonal closed cross-section in a cross-sectional form developed by cutting the component at a position corresponding to the ridge line located at the innermost side in the radial direction to provide a flange portion extending along the ridge line at the resulting respective ends, and press-forming the pre-processed part to deform inwardly in the cross-sectional direction at a position of one or more of the plural ridge lines to butt the ridge lines located at the innermost side and the flange portions to each other.

Abstract: There is provided a method of manufacturing a curved channel part having a curved portion in a vertical wall portion by press forming, the method restricting stretch flange deformation, which occurs in the vertical wall portion and a flange portion. The method includes a shear deformation step as a step of forming the vertical wall portion. In the shear deformation step, a boundary-side portion of a base section of a blank with respect to a deformation section, and an outer portion of the deformation section are individually restrained, a portion to be a vertical wall portion of the deformation section is shear-deformed in a sheet face, and a material is caused to flow from a portion separated from a curved portion toward the curved portion in an outer edge portion of the portion to be the vertical wall portion.

Abstract: By using, as a raw material, a thick hot-rolled steel sheet having a chemical composition containing, by mass %, C: 0.02% or more and 0.10% or less, Si: 0.05% or more and 0.30% or less, Mn: 0.80% or more and 2.00% or less, and Nb: 0.010% or more and 0.100% or less and satisfying the condition that a carbon equivalent Ceq is 0.25% or more and 0.50% or less, a microstructure including a bainitic ferrite phase and/or a bainite phase, a high strength of 52 ksi or more in terms of yield strength and a high toughness of ?45° C. or lower in terms of fracture transition temperature vTrs, an electric resistance weld zone having a microstructure including a bainitic ferrite phase and/or a bainite phase and satisfying the condition that the ratio of the average crystal grain size of the coarsest-grain portion to the average crystal grain size of the finest-grain portion is 2.0 or less in every portion in the wall thickness direction is obtained.