| 摘要 |
PROBLEM TO BE SOLVED: To provide a boom capable of increasing the buckling strength while maintaining the bending strength in the boom of a vertically long section. SOLUTION: In the boom, its vertically long section is constituted of an upper plate part 31, side plate parts 32, 32 on both sides longer than the upper plate part 31, and a lower plate part 33, and a lower plate inclined part 33a is formed by folding both ends of the lower plate part 33 inwardly so as to form the predetermined lower plate folding angleβwith respect to the center of the lower plate part 33. A side plate inclined part 32a is formed by folding lower portions of both side plate parts 32 so as to form the side plate folding angleαsmaller than the lower plate folding angleβwith respect to upper portions of the side plate parts 32. COPYRIGHT: (C)2011,JPO&INPIT |
