| 摘要 |
PROBLEM TO BE SOLVED: To prevent the deformation of a part of a center hole in a blank, and to suppress the reduction in wall thickness and degradation of the strength of the blank in a sheet metal member forming method in which the form-rolling is achieved by pressing a form-rolling roll to be rotated following the blank against an outer circumferential part of the blank expanded from an outer circumference of upper and lower dies in the radial direction while the blank is pressed and held between an upper end face of the rotating lower die and a lower end face of the rotated upper die 8. SOLUTION: A plate part to be pressed and held by the upper and lower dies 8 and 9 of the blank 4 is formed in a conical shape in advance, the lower end face of the upper die 8 is formed to a projecting conical surface 14 to be engaged with the conical shape of the blank 4, the upper end face of the lower die 9 is formed into a recessed conical surface 11 to be engaged with the conical shape of the blank 4, and a conical part 5 of the blank 4 is pressed and held between the projecting conical surface 14 of the upper die 8 and the recessed conical surface 11 of the lower die 9.
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