Blank material, method for press molding blank material, and press molding device

Abstract

A molding recessed part of a lower mold constituting a press molding device is provided with a first blank holder, and a circular second blank holder is freely movably provided on one outer peripheral side of the first blank holder. Meanwhile, of first and second blank holes opened in blank material, straight-line parts of the second blank hole have formed therein a pair of tensile force adjusting parts, and arched parts of first and second opening parts are mounted on the second blank holder. Furthermore, when draw forming of the blank material is performed, the tensile force imparted to the straight-line parts to the outside is adjusted by the tensile force adjusting parts, and the tensile force imparted to the arched parts to the outside in the radial direction is adjusted by the second blank holder.

What is claim is: 
     
         1 . A blank material for which draw forming is performed in a press forming device to make a body panel of an automobile, the blank material comprising an opening part including arched parts provided in an up-down direction of the body panel and connection parts each having an approximately straight line shape provided in a front-rear direction of the body panel that is approximately orthogonal to the arched parts and connected to the arched parts,
 wherein a tension adjusting part is provided to the connection part, the tension adjusting part extending to an inside of the opening part and configured to adjust tension applied outwardly in forming.   
     
     
         2 . The blank material according to  claim 1 , wherein the tension adjusting part is formed for each of a pair of the connection parts. 
     
     
         3 . The blank material according to  claim 1  or  2 , wherein each of the arched parts is formed in a manner that the arched part is smaller than a formed arched part of a formed body in which the arched part has been formed, and the arched part has a shape that is close to the formed arched part. 
     
     
         4 . A press forming method in which draw forming is performed for a blank material including an opening part that includes arched parts and connection parts each having an approximately straight line shape and connected to the arched parts,
 wherein an edge of the opening part is pressurized and held between an upper die and a first blank holder provided to a lower die, and   the arched parts positioned outside a held part of the blank material held between the upper die and the first blank holder is pressurized and held between the upper die and a second blank holder provided outside the first blank holder.   
     
     
         5 . The press forming method according to  claim 4 , wherein a bead is formed by holding, between the upper die and the first blank holder, a tension adjusting part extending from the connection part to an inside of the opening part. 
     
     
         6 . A press forming device configured to perform draw forming for a blank material including an opening part that includes arched parts and connection parts each having an approximately straight line shape and connected to the arched parts, the press forming device comprising:
 an upper die;   a lower die disposed so as to face the upper die and including a mounting surface on which the blank material is mounted;   a first blank holder disposed so as to face the upper die and configured to hold an edge of the opening part of the blank material with the upper die; and   a second blank holder disposed outside the first blank holder and configured to hold, between the second blank holder and the upper die, the arched parts positioned outside a held part of the blank material held between the first blank holder and the upper die,   wherein the first blank holder and the upper die include a bead configured to hold with pressure a tension adjusting part extending from the connection part of the blank material to an inside.   
     
     
         7 . The press forming device according to  claim 6 , wherein the second blank holder has a circular shape. 
     
     
         8 . The press forming device according to  claim 6  or  7 , wherein the bead extends along a direction that is approximately orthogonal to an extending direction of the tension adjusting part.