| 摘要 |
PURPOSE:To obtain a semiclosed forging die that can forge a work having deep bulged part at high yield and with sufficient filling up, by forming continuous engraving faces on tapered parts raised in upper and lower dies. CONSTITUTION:For instance, a semiclosed forging die for rough forging and finishing of a differential side gear of an automobile consists of upper and lower dies 11 and 12, 21 and 22 respectively. Continuous engraving faces 11a, 12a are provided on tapered parts 11c, 12c raised on outer edge A of a forging space between the dies 11, 12. The same applies to dies 21, 22. Tapered parts 11c, 12c come into contact at the bottom dead center of the press. When a material flattened in the first process is put in the die 12 and the die 11 is lowered, the distance between tapered parts 11c, 12c becomes suddenly narrow after initial open forging, and burrs formed become as thin as paper. Tapered parts draw near the bottom dead center of the die 12, and strong compressive force is applied on the material by thrusting effect of the tapered parts. Accordingly, satifactory filling up can be obtained without using resistance of burrs. Finishing work can be performed similarly. |
