| 摘要 |
PROBLEM TO BE SOLVED: To reduce weight of a work arm; and to secure rigidity, by forming a square cylindrical body having a cross section of a quadrangular shape, by using a plurality of plate materials different in the plate thickness in the longitudinal direction. SOLUTION: One plate-like body 28 partially different in the plate thickness in the longitudinal direction, is formed by performing butt welding of a thin plate material 29 and thick plate material 31 and 32 in the longitudinal direction. A U-shaped member 33 having a cross section of a U shape is molded by a press, by bending this plate-like body 28 over the total length. The other plate-like body 34 is butted and joined by welding to the opening side positioned on the lower side of the U-shaped member 33. Thus, a square cylindrical body having a cross section of a quadrangular shape, and becoming a main part of an arm, is formed by using the U-shaped member 33 and the other plate-like body 34. COPYRIGHT: (C)2005,JPO&NCIPI
|
