Producing method and producing apparatus of press formed product

Abstract

A producing method of the press formed product includes a preparation step of preparing a metal sheet as a starting material, and a press working step of performing press working on the starting material by using a punch, and a pad and a die that are paired with the punch. The press working step includes a first step of forming, by the punch and the pad, the entire region of a top panel part, the entire region of each of a ridge line parts including the shape-changing part, and a region up to a predetermined height from the border between a vertical wall part and the ridge line part of a region of each of the vertical wall parts, and a second step of forming, subsequent to the first step, by the punch and the die, the remaining regions with the starting material sandwiched between the punch and the pad.

1 . A method for producing a press formed product from a starting material,
 the press formed product comprising a top panel part, vertical wall parts respectively extending from both ends of the top panel part, and ridge line parts between the vertical wall parts and the top panel part, and including a shape-changing part in a part of the ridge line parts,   the producing method comprising:   a preparation step of preparing a metal sheet as the starting material; and   a press working step of performing press working on the starting material by using a punch, and a pad and a die that are paired with the punch, and   the press working step including:   a first step of forming, by the punch and the pad, at least a region adjacent to the shape-changing part of a region of the top panel part, at least a region of the shape-changing part of a region of each of the ridge line parts, and at least a region adjacent to the shape-changing part of a region of each of the vertical wall parts and up to a predetermined height from a border between the vertical wall part and the ridge line part; and   a second step of forming, subsequent to the first step, by the punch and the die, the remaining regions, with the starting material sandwiched between the punch and the pad.   
     
     
         2 . The producing method of the press formed product according to  claim 1 ,
 wherein the predetermined height is 2 mm or more from the border between the vertical wall part and the ridge line part, and is equal to or less than a half of the total height of the vertical wall part.   
     
     
         3 . The producing method of the press formed product according to  claim 1 ,
 wherein, in the first step, the entire region of the top panel part, the entire region of each of the ridge line parts, and a region up to the predetermined height from the border between the vertical wall part and the ridge line part of a region of each of the vertical wall parts are formed by the punch and the pad, and   in the second step, a region beyond the predetermined height of the region of each of the vertical wall parts is formed by the punch and the die.   
     
     
         4 . The producing method of the press formed product according to  claim 1 ,
 wherein the shape-changing part of the ridge line parts is at least one of (a) to (f) as follows:   (a) the height of the ridge line part is changed;   (b) the arc length in a cross section of the ridge line part is changed;   (c) the ridge line part is twisted;   (d) the ridge line part is bent in a width direction;   (e) the ridge line part protrudes or is hollowed in the width direction; and   (f) the radius of curvature in the cross section of the ridge line part is changed.   
     
     
         5 . An apparatus for producing a press formed product from a starting material,
 the press formed product comprising a top panel part, vertical wall parts respectively extending from both ends of the top panel part, and ridge line parts between the vertical wall parts and the top panel part, and including a shape-changing part in a part of the ridge line parts,   the producing apparatus comprising a punch, and a pad and a die that are paired with the punch,   the punch including a front end surface corresponding to a region of the top panel part, side surfaces corresponding to regions of the respective vertical wall parts, and punch shoulder parts corresponding to regions of the respective ridge line parts, and   the pad including a bottom surface corresponding to at least a region adjacent to the shape-changing part of a region of the top panel part, a corner part corresponding to at least a region of the shape-changing part of a region of each of the ridge line parts, and an inner side surface corresponding to at least a region adjacent to the shape-changing part of a region of each of the vertical wall parts and up to a predetermined height from a border between the vertical wall part and the ridge line part.   
     
     
         6 . A producing apparatus of a press formed product, comprising:
 a punch including a front end surface, side surfaces, and punch shoulder parts provided between the front end surface and the side surfaces, the punch shoulder parts being provided with a shape-changing part in a part of a longitudinal direction of the punch;   a pad including a bottom surface opposing the front end surface of the punch, inner side surfaces opposing a part of the side surfaces of the punch, and corner parts provided between the bottom surface and the inner side surfaces and opposing the punch shoulder parts; and   a die including inner side surfaces opposing regions of the side surfaces of the punch, except for regions opposing the inner side surfaces of the pad of the regions of the side surfaces of the punch.   
     
     
         7 . The producing apparatus of the press formed product according to  claim 5 ,
 wherein the predetermined height is 2 mm or more from the border between the vertical wall part and the ridge line part, and is equal to or less than a half of the total height of the vertical wall part.   
     
     
         8 . The producing apparatus of the press formed product according to  claim 5 ,
 wherein the bottom surface of the pad corresponds to the entire region of the top panel part, each of the corner parts of the pad corresponds to the entire region of each of the ridge line parts, and each of the inner side surfaces of the pad corresponds to a region up to the predetermined height from the border between the vertical wall part and the ridge line part of a region of each of the vertical wall parts, and   wherein the die includes inner side surfaces corresponding to regions beyond the predetermined height of regions of the respective vertical wall parts.   
     
     
         9 . The producing apparatus of the press formed product according to  claim 8 ,
 wherein the die is divided to correspond to each of the vertical wall parts, and   wherein the producing apparatus comprises a die moving mechanism that moves each of the dies toward a respective one of the side surfaces of the punch after completion of pushing-in of the starting material into the pad by the punch.