WORK MACHINE

PROBLEM TO BE SOLVED: To elongate a fatigue life of a boss welding part by reducing stress at a welded part between a boss and a side plate without reducing rigidity of the boss, thereby improving durability and reliability of a work machine.SOLUTION: A work machine comprises a boss 9 including a flange part 9C and a boss body 9B through which a pin insertion hole 9A is formed, the flange part 9C having an outer periphery fixed to a plate by welding, the work machine including a connection part at which a plurality of components are relatively rotatably connected using the boss 9 and a pin inserted into the pin insertion hole 9A. The boss 9 includes a groove part 15 formed on the flange part 9C, the groove part 15 being arranged on the side closer to the boss body 9B in the boss 9's radial direction than a welded part 13 provided on the outer periphery; a plate thickness dimension of the flange part 9C's part at which the groove part 15 is formed is smaller than that of the plate 12A.SELECTED DRAWING: Figure 2 【課題】本発明の目的は、ボスの剛性を低下させることなくボスと側板との溶接部の応力を低下させ、ボス溶接部における疲労寿命を大きくすることにあり、これにより作業機械の耐久性及び信頼性を向上することにある。【解決手段】ピン挿入孔９Ａが形成されたボス本体部９Ｂとつば部９Ｃとを有し、つば部９Ｃの外周部が板材に溶接により固定されたボス９を備え、ボス９とピン挿入孔９Ａに挿入されたピンとで複数の部品を相対的に回動可能に連結した連結部を有する作業機械において、ボス９はつば部９Ｃに形成された溝部１５を有し、溝部１５は外周部に設けられた溶接部１３よりもボス９の径方向においてボス本体部９Ｂ側に配置され、溝部１５が形成された部分のつば部９Ｃの板厚寸法は板材１２Ａの板厚寸法よりも小さい。【選択図】図２