To provide a method of manufacturing a closed cross-sectional member made of metal, by which the closed cross-sectional member is manufactured comparatively easily from a planar workpiece even when the member has a complicated cross-sectional shape.
This method includes a first press-forming stage where a planar workpiece W1 is formed into a projective shape and a first projecting part W2a is also formed in the projective top surface part W2, and a second press-forming stage where projective side face parts W3, W4 are displaced to the inward side respectively by press-forming the first projecting part W2a. Furthermore, the method includes a projecting part forming stage where second projecting parts W3f, W4f are formed in the projective side face parts W3, W4 and a third press-forming stage where both side face parts which are adjacent to the second projecting parts W3f, W4f are displaced to the inward side respectively by press-forming the second projecting parts W3f, W4f. The second projecting parts W3f, W4f and the first projecting part are press-formed and the planar workpiece W1 is made into the closed cross section.
ISHIDA YASUAKI
SAITO NAOKO
MIZOGAMI TATSUSHI
MURASE KENJI
Mitsuo Tanaka
Fukuoka Masaaki