| 摘要 |
A bushing having an outer sliding surface is produced by a die forming method without machining. A crowning shape is provided to the outer surface so that the outer diameter of the bushing is smaller at its opposite longitudinal ends, and increases progressively toward a central zone of the bushing. A cylindrical bushing blank is fitted on distal end portion of a vertically-movable mandrel. Next, one of an upper die and a lower die is reactively moved toward the other to plastically work the bushing blank by the both dies and the mandrel, thereby working the bushing. An inner diameter of the upper die is larger at its lower end, and decreases progressively away from the lower end, and an inner diameter of the lower die is larger at its upper end, and decreases progressively away from the upper end. |
