| 摘要 |
PROBLEM TO BE SOLVED: To suppress generation of a forming defect near a joining part of a combined blank material and to facilitate a die repair in tryout, etc. SOLUTION: A cross sectional shape of a bead 16 is a trapezoid, a height, a width and the radius of curvature of the trapezoid in a boundary region E1 including a joining part 18 are larger as compared to a normal region E3, thus, a large in flowing resistance is imparted. Further, a gradually changing region E2 of a trapezoidal cross sectional shape is arranged between the a boundary region E1 and the normal region E3.
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