| 摘要 |
PROBLEM TO BE SOLVED: To provide a method and device capable of surely and precisely forming a tubular member having a square cross section over the entire length or in partial part by press forming with a simple configuration. SOLUTION: This forming device 30 is provided with an upper die 31 and lower die 32 as a 1st and 2nd dies for forming corner parts D1-D4 by making each preliminary corner parts d1-d4 to bend to prescribed angles by performing press forming of a twice bent rough shape material p2 on which plural preliminary corner parts d1-d4 are formed and side-face dies 33, 33 as the 3rd die for pressing parts to be made into side-part planes F2, F3 later so as to make edges S which are opposed to each other of the twice bent rough shape material p2 closely when the twice bent rough shape material p2 arranged between the upper die 31 and the lower die 33 is formed by pressing.
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