| 摘要 |
PROBLEM TO BE SOLVED: To provide a construction machinery arm capable of reducing stress that occurs around a boom coupling boss 44 to prevent crack of a welding part that bonds an outer surface of each of flange parts 44b, 44b of the boom coupling boss 44 to an outer surface of each of cutouts 38a, 38a of each of upper side plates 38, 38.SOLUTION: An outer surface of each of step parts 44c, 44c of a boom coupling boss 44 is in contact with an inner surface of each of cutouts 38a, 38a and is welded to an outer surface of each of the cutouts 38a, 38a over a circular arc part outer peripheral edge from the outside of an arm 20 to be bonded together. In addition, an inner surface of each of the step parts 44c, 44c of the boom coupling boss 44 is welded to the inner surface of each of the cutouts 38a, 38a of each of upper side plates 38, 38 at a circular arc part outer peripheral edge of each of rear flange parts 44e, 44e from the inside of the arm 20 to be bonded together. |
