Abstract: A coupling structure includes a hollow rod section formed of a metal pipe and fastening sections formed by plastic deformation of the metal pipe so as to be connected with end sections of the hollow rod section. The fastening section includes a pair of base end sections which are each connected with a peripheral wall section forming a closed cross-section at the end section of the hollow rod section, and are separated from each other, and a bottom wall including a flat surface connected with the pair of the base end sections, and a pair of front end sections including a pair of side walls curving inwards from at least widthwise end sections of the bottom wall on a base end section side.

Abstract: Provided is a shearing method which can produce a worked material having a sheared edge excellent in surface perpendicularity and surface properties with a good productivity while suppressing tool wear and damage. The method comprises a first shearing step of placing a first blank having first and second surfaces on a first die so that said second surface is arranged on said first die side, and shearing said first blank from said first surface toward said second surface in a sheet thickness direction of said first blank by a first punch arranged at said first surface side to obtain a first punched out material and first worked material; and a second shearing step of placing a second blank and (x) using said first punched out material as a second punch, (y) using said first worked material as a second die, or both thereof.

Abstract: Provided is a steel material shearing method that enables highly productive and low-cost production of a steel material with a sheared surface having excellent hydrogen embrittlement resistance, fatigue strength, and stretch flangeability. The shearing method comprises making a clearance between a die and a punch 5 to 80% of a sheet thickness of a workpiece, shearing the workpiece using the punch, and, by utilizing a punched material punched out by the punch, pressing an end face of the punched out material against the sheared surface of the worked material on the die to produce a steel sheet with a sheared edge having excellent hydrogen embrittlement resistance and fatigue strength.

Abstract: A cutting method using a stamping press according to the present disclosure is a method to cut a workpiece that is configured from a first metal sheet and a second metal sheet joined at a weld portion and that has a heat-affected zone around the weld portion, in which the workpiece is cut using a punch. The punch includes a flat portion and a projecting portion projected more toward the workpiece than a flat portion of the punch. The workpiece is positioned with respect to the punch at a position such that the projecting portion starts cutting at least at one out of the heat-affected zone or the weld portion before the flat portion cuts the workpiece. The workpiece is then cut by moving the punch and a die relative to each other in this state of positioning so as to shear across the weld portion on the workpiece.

Abstract: Provided is a plastic working method of steel including austenite, the method including: analyzing a strain ratio ?x of an estimated breaking point which is specified during plastic deformation of the steel; heating a steel such that a local temperature Tlocal is within a temperature range indicated by the following expression 1, when T?x represents a strain-induced-transformation-maximum-ductility-temperature in the unit of ° C. for the strain ratio ?x, ?L?x represents the standard deviation of a fitted curve of critical equivalent strain which depends on the strain ratio ?x on a lower temperature side than T?x, ?H?x represents the standard deviation of a fitted curve of critical equivalent strain which depends on the strain ratio ?x on a higher temperature side than T?x, and Tlocal represents a local temperature in the unit of ° C. of the estimated breaking point; and plastically deforming the steel after heating: T?x?2×?L?x?Tlocal?T?x+1.25×?H?x??(Expression 1).

Abstract: [Object] To enable flexible molding of a punch-nose in press working for obtaining a molded product including a U-shaped portion in a cross-section. [Solution] Provided is a press-working apparatus configured to provide a molded product by performing press working on a work, the molded product including, in a cross-section, a U-shaped portion including a bottom, a wall, and a punch-nose between the bottom and the wall, the press-working apparatus including: a die in which a recessed portion to receive the U-shaped portion is formed; a first punch that sandwiches a central area of the bottom with a bottom surface of the recessed portion; and a second punch that is pushed into the recessed portion later than the first punch, to restrain the wall between the second punch and a side surface of the recessed portion, and sandwich the work with the bottom surface to mold a peripheral area of the bottom and the punch-nose.

Abstract: A stretch flange crack prediction method of predicting initiation of stretch flange cracks that occurs in a flange end section during stretch flange forming of a deformable sheet, includes: a measurement value acquisition process of acquiring, for each of a plurality of sheet-shaped test pieces, a fracture strain measurement value, a normal strain gradient measurement value, and a circumferential strain gradient measurement value; a CAE analysis process of acquiring a maximum major strain maximum element having a highest maximum major strain, a normal strain gradient of the maximum major strain maximum element, and a circumferential strain gradient of the maximum major strain maximum element; a fracture determination threshold acquisition process of acquiring a fracture determination threshold by converting the fracture strain measurement value; and a prediction process of predicting that stretch flange cracks will be initiated, when the maximum major strain is equal to or higher than the fracture determinati

Abstract: An apparatus for identification of a cause of occurrence of springback having a press forming analyzer for numerically analyzing forming conditions of press forming to obtain forming data of a press formed part, a springback analyzer for numerically analyzing said forming data to calculate a springback value, and a processor for processing at least one of a physical property value and physical property quantity data of part of the regions of said press formed part among forming data of said press formed part and making said springback analyzer calculate the springback value based on the results of said processing.

Abstract: A blank shape determining method includes: a process of making a forming analysis of forming a reference blank into a reference formed product and a acquiring sheet thickness distribution and a plastic strain distribution; a process of acquiring a forming failure evaluation index for the reference blank; a process of estimating a region, which includes an end edge portion at which the forming failure evaluation index exceeds a predetermined threshold, within the reference blank as a forming failure region; a process of generating a plurality of corrected blanks; a process of making a forming analysis of forming the corrected blanks into corrected formed products and acquiring a sheet thickness distribution and a plastic strain distribution; a process of acquiring the forming failure evaluation index for the corrected formed product; and a process of determining a shape of the corrected blank having a smallest maximum value of the forming failure evaluation index as a shape of a blank provided for press formin

Abstract: A press-forming tool comprising: a punch including a punch portion and a plate portion transferring shape to a blank material; a die paired with the punch and opposes the punch portion; a wrinkle suppression mold including a first surface opposing the plate portion and comes into contact with the plate portion at a press-forming ending point, a second surface opposing the die and holds the blank material along with the die, and a third surface continued between the first and second surface and opposes the punch portion, and disposed between the third surface and the punch portion via a gap; a pressure receiving portion including a groove portion on the first surface of the wrinkle suppression mold; and a wrinkle suppression force increasing portion disposed on a surface opposing the first surface of the plate portion, protrudes toward the pressure receiving portion, and generates a reaction force opposed to a pressing direction when pressed in the pressing direction in end-phase of a press-forming.

Abstract: A producing method to be disclosed is a producing method for producing a formed metal item that includes a tubular part with a slit. This producing method includes a step (i) of forming U-shaped part having a U-shaped cross section by deforming a metal plate, and a step (ii) of forming the tubular part with the slit by deforming the U-shaped part using a die assembly with a protruding part in such a manner that two end parts of the U-shaped part clamp the protruding part. In step (ii), a cross-section peripheral length LH of the tubular part is made shorter than a cross-section length LU of the U-shaped part.

Abstract: A method of forming which forms a metal sheet so that it does not break without changing the material of the metal sheet and the forming process, comprising bonding a reinforcement to part of the metal sheet and then forming the metal sheet.

Abstract: A method of production of a shaped article able to suppress occurrence of shaping defects, that is, a method of production of a shaped article including a first step of press-forming a metal plate (1a) into a U-shape to obtain a U-shaped article (1b) having a bottom part (2) straight extending in a longitudinal direction and a second step of press-forming the U-shaped article (1b) to bend it in the longitudinal direction so that the bottom part (2) of the part projects to the inside and obtain a U-cross-section bent article (1c).

Abstract: A method of identification of a cause of occurrence of springback comprising a press forming analysis step of numerically analyzing forming conditions of press forming to obtain forming data of a press formed part, a processing step of processing at least one of a physical property value and physical property quantity data of part of the regions of said press formed part among forming data of said press formed part, and a springback value calculation step of calculating a springback value based on the results of said processing.

Abstract: Provided is a line displacement evaluation method of evaluating line displacement occurring in a press-formed article in press forming of forming a character line. This method includes acquiring a cross section profile of the press-formed article measured so as to traverse the character line formed in the press-formed article; calculating a 4th order differential coefficient of the acquired cross section profile; and evaluating the line displacement, on the basis of the calculated 4th order differential coefficient of the cross section profile.

Abstract: An evaluation method of a plastic material includes: a first shearing process of performing simple shearing deformation with respect to a first plastic sheet; a second shearing process of performing simple shearing deformation with respect to a second plastic sheet; a first partial stress-strain curve data obtaining process of obtaining first partial stress-strain curve data; a second partial stress-strain curve data obtaining process of obtaining second partial stress-strain curve data; and a synthesized stress-strain curve data obtaining process of obtaining synthesized stress-strain curve data based on the first partial stress-strain curve data and the second partial stress-strain curve data.

Abstract: In the present invention, in a piercing punch and a burring punch which are shaft members having a first axis line as the center axis lines and are provided so as to be movable along the first axis line, first, after prepared holes having the first axis line as the center axis lines with respect to the first wall portion and the second wall portion are formed using the piercing punch, burring holes having the first axis line as the center axis lines with respect to the first wall portion and the second wall portion are formed using the burring punch.

Abstract: A method for manufacturing a press-formed product includes: a first step of preparing a long material having a bending portion; and a second step of decreasing curvature of the bending portion while restricting both ends of the long material in a longitudinal direction.

Abstract: A load-applying device of a press-forming die includes a rod which includes a first end, a second end, and a flange, a lamination coned disc spring in which a plurality of coned disc springs having a center hole, to which the first end of the rod is inserted, are laminated, a first plate which includes a first through hole to which the first end of the rod is inserted and abuts the lamination coned disc spring, a second plate which includes a second through hole to which the second end of the rod is inserted and abuts the flange; and a gap fixing member which is detachably provided between the first plate and the second plate and fixes a gap between the first plate and the second plate so as to maintain the gap by which the lamination coned disc spring biases the flange to the second plate. The second end and the first plate relatively move in a mutually approaching direction during press-forming, and the lamination coned disc spring is compressed.

Abstract: [Object] To provide a press-molding apparatus capable of appropriately thickening a vertical wall portion while preventing the occurrence of buckling. [Solution] Provided is a press-molding apparatus configured to mold a press-molded product by performing press working on a work, the press-molding apparatus including: a support member that supports the work with a first thickness having a hat-shaped cross-section or a U-shaped cross-section; a punch member that moves relative to the support member to execute press working so as to reduce a height of a vertical wall portion of the work and thicken the vertical wall portion to a second thickness; and a pad member that faces the support member with the vertical wall portion to be thickened placed therebetween, the pad member being biased by a biasing member and having its distance to the support member kept equal to or smaller than the second thickness during the press working.