| 摘要 |
PURPOSE: An arm center boss for controlling generation of fatigue cracks is provided to prevent a fatigue life from being reduced due to fatigue cracks generated on a welded part. CONSTITUTION: An arm center boss(240) for controlling generation of fatigue cracks comprises a hole(242), a plate-shaped boss body(244). One end of the rotary shaft of an arm is inserted into the hole. The boss body is formed around the hole in a reverse-triangular shape and has a welded part(246) having a fixed point(246c) and two sides(246a,246b). The sides are adjacent to the fixed point and control the generation of fatigue cracks. |
