Press-formed article manufacturing method

Abstract

A press-formed article manufacturing method that can reduce the influence of a shape variation of a blank. The press-formed article manufacturing method includes: a reference press-formed article shape acquisition step of acquiring a reference press-formed article shape; a corrugated blank press-formed article shape acquisition step of acquiring a corrugated blank press-formed article shape; a first deviation amount acquisition step of finding first deviation amounts between the reference press-formed article shape and the corrugated blank press-formed article shape; a period-shifted corrugated blank press-formed article shape acquisition step of acquiring a period-shifted corrugated blank press-formed article shape; a second deviation amount acquisition step of finding second deviation amounts between the reference press-formed article shape and the period-shifted corrugated blank press-formed article shape; a measures-required portion specifying step of specifying measures-required portions; and a bead providing step of providing beads for an actual die.

1 . A press-formed article manufacturing method for manufacturing a press-formed article by performing press forming with use of a press die on a blank extracted from a metal sheet having a shape variation, the press-formed article manufacturing method comprising:
 a reference press-formed article shape acquisition step of acquiring a press-formed article shape after die release as a reference press-formed article shape by performing press forming analysis to perform press forming with use of a flat blank model having a flat shape by a predetermined die model set based on a shape of a target press-formed article;   a corrugated blank press-formed article shape acquisition step of acquiring a press-formed article shape after die release as a corrugated blank press-formed article shape by generating a corrugated blank model with corrugations having a wavelength and an amplitude set based on the shape variation and performing press forming analysis to perform press forming with use of the generated corrugated blank model by the predetermined die model;   a first deviation amount acquisition step of finding a deviation portion where the reference press-formed article shape and the corrugated blank press-formed article shape deviate from each other, and a first deviation amount as a deviation amount in the deviation portion, by comparing the reference press-formed article shape with the corrugated blank press-formed article shape;   a period-shifted corrugated blank press-formed article shape acquisition step of acquiring a press-formed article shape after die release as a period-shifted corrugated blank press-formed article shape by generating a period-shifted corrugated blank model of at least one type with corrugations having the same amplitude as the corrugations of the corrugated blank model and shifted in period from the corrugations of the corrugated blank model, and performing press forming analysis to perform press forming with use of the generated period-shifted corrugated blank model by the predetermined die model;   a second deviation amount acquisition step of finding a deviation portion where the reference press-formed article shape and the period-shifted corrugated blank press-formed article shape of the at least one type deviate from each other, and a second deviation amount as a deviation amount in the deviation portion, by comparing the reference press-formed article shape with the period-shifted corrugated blank press-formed article shape of the at least one type;   a measures-required portion specifying step of specifying, as measures-required portions, respective portions of the press-formed article which portions correspond to a portion having a deviation amount exceeding a predetermined threshold as the first deviation amount and a portion having a deviation amount exceeding the predetermined threshold as the second deviation amount; and   a forming accuracy improving step of correcting a shape of at least either one selected from a forming surface of an actual die as a press die to be used in manufacture of the press-formed article and an actual blank as the blank to be used in the manufacture of the press-formed article in such a manner as to reduce the deviation amounts in the measures-required portions specified in the measures-required portion specifying step.   
     
     
         2 . The press-formed article manufacturing method according to  claim 1 , wherein:
 the first deviation amount acquisition step acquires, as the first deviation amount, a difference between a spring back amount in a predetermined portion of the reference press-formed article shape and a spring back amount of a portion of the corrugated blank press-formed article shape which portion corresponds to the predetermined portion of the reference press-formed article shape; and   the second deviation amount acquisition step acquires, as the second deviation amount, a difference between a spring back amount in a predetermined portion of the reference press-formed article shape and a spring back amount of a portion of the period-shifted corrugated blank press-formed article shape which portion corresponds to the predetermined portion of the reference press-formed article shape.   
     
     
         3 . The press-formed article manufacturing method according to  claim 1 , wherein
 the forming accuracy improving step includes a bead providing step of providing beads for portions of the forming surface of the actual die which portions are to form the measures-required portions, or the measures-required portions and peripheral portions around the measures-required portions.   
     
     
         4 . The press-formed article manufacturing method according to  claim 3 , wherein
 in the bead providing step, each of the beads is provided for the actual die such that a longitudinal direction of a bead mark formed on the press-formed article by the each of the beads provided for the actual die is along a direction intersecting with an end side of the press-formed article which end side is closest to a corresponding measures-required portion.   
     
     
         5 . The press-formed article manufacturing method according to  claim 3 , wherein:
 the actual blank has a shape variation in which recesses and protrusions are consecutive along a predetermined direction; and   in the bead providing step, each of the beads is provided for the actual die such that, in a corresponding measures-required portion of the press-formed article, a longitudinal direction of a bead mark formed on the press-formed article by the each of the beads provided for the actual die is along a direction where the recesses and the protrusions in the shape variation of the blank are consecutive.   
     
     
         6 . The press-formed article manufacturing method according to  claim 3 , further comprising:
 an actual press forming step of performing press forming on the blank with use of the actual die provided with the beads, in such a manner as to form bead marks in the measures-required portions in the press-formed article or in the measures-required portions and respective peripheral portions around the measures-required portions; and   a restriking step of performing repressing on the press-formed article acquired by the press forming in the actual press forming step and crushing the bead marks.   
     
     
         7 . The press-formed article manufacturing method according to  claim 1 , wherein
 the forming accuracy improving step includes   a developed blank model measures-required portion specifying step of specifying measures-required portions in a developed blank model acquired by setting the measures-required portions on any of the reference press-formed article shape, the corrugated blank press-formed article shape, and the period-shifted corrugated blank press-formed article shape, and developing, to a blank model, the any of the reference press-formed article shape, the corrugated blank press-formed article shape, and the period-shifted corrugated blank press-formed article shape; and   a blank bead providing step of providing beads for portions of the actual blank which portions correspond to the measures-required portions specified in the developed blank model measures-required portion specifying step.   
     
     
         8 . The press-formed article manufacturing method according to  claim 7 , wherein
 in the blank bead providing step, each of the beads is provided for the actual blank such that a longitudinal direction of the each of the beads is along a direction intersecting with an end side of the actual blank which end side is closest to a corresponding measures-required portion.   
     
     
         9 . The press-formed article manufacturing method according to  claim 8 , wherein:
 the actual blank has a shape variation in which recesses and protrusions are consecutive along a predetermined direction; and   in the blank bead providing step, each of the beads is provided for the actual blank such that, in a corresponding measures-required portion of the actual blank, a longitudinal direction of the each of the beads provided for the blank is along a direction where the recesses and the protrusions in the shape variation of the actual blank are consecutive.   
     
     
         10 . The press-formed article manufacturing method according to  claim 7 , further comprising:
 a forming step of performing press forming on the actual blank provided with the beads by the actual die; and   a step of performing press forming to crush the beads after the forming step.