PURPOSE: To improve strength and rigidity by a method wherein the ends on one side of a pair of right and left outer main rib parts and the ends on one side of oblique main rib parts are coupled to the two ends of a first frame member, the two ends of a second frame member are coupled to the ends on the other side of a pair of the outer main rib parts, and the other end of the oblique main rib part is coupled to the central part of the second frame member.
CONSTITUTION: One end of an oblique rib part 11 is brought into adjacent contact with the ends on one side of a pair of outer main rib parts 10 through a first coupling member 14 and the other end of the oblique main rib part 11 is arranged approximately to a central part between the other ends of the outer main rib parts 10 through a second coupling member 15. An outer auxiliary rib part 12 is disposed between each outer main rib part 10 and the oblique main rib part 11. A connection position 12a between the oblique main rib part 11 and the outer auxiliary rib part 12 is changed into a connection position 13a and an inner auxiliary rib part 13 is disposed between the two oblique rib parts 11. Further, the two ends of a first frame member 16 is integrally coupled to a pair of the first coupling members 14. The two ends of the second frame member 17 is coupled to the other ends of a pair of the outer rib parts 10 and the central part of the second frame member 17 is coupled to the second coupling member 15.
YOSHIDA TAKASHI
SATO MASAKAZU
SHIODA SHUNTA
TAMIYASU YOSHIBUMI
SHIOZAWA YASUO
SHOWA ALUMINUM CORP