| 摘要 |
PROBLEM TO BE SOLVED: To properly and easily weld and join reinforcing members by allowing bending parts and bending end parts of respective plate members bent in a zigzag shape or plural plate members having a cross section formed in a channel shape to abut to an inner wall of a work arm. SOLUTION: An arm 8 is formed as a box-shaped structure out of upper/ lower plates 8a, 8b extending in the lengthwise direction and left/right side plates 8c, 8d. Reinforcing members 9 are formed by arranging plural bending parts in the lengthwise direction of the arm 8 by bending a belt-like plate member in a zigzag shape. A height and a width are formed by gradually changing these so that the bending parts abut to an inner wall of a box-shaped cross section. A work arm structure is positioned in the box-shaped structure by temporary attaching welding, and is integrally joined from the outside of the box-shaped structure by laser welding. Both end parts of the plate member are bent at an almost right angle on the inside of the box-shaped structure, and may be constituted so as to join plural reinforcing members formed in a cross-sectional U shape. Thus, the reinforcing members can be properly and easily joined, and a work arm can be effectively reinforced.
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