| 摘要 |
<p>This invention provides a mold for forging (30) having a venting passage (34) for discharging gas confined within a molding hole (35) in a forging mold during molding. The venting passage has a plurality of step parts different from each other in sectional area perpendicular to the gas flow direction. The area of the opening part in a first step part (X), which faces the wall surface of the molding hole, is smaller than the area of the opening part in a second step part (Y) connected thereto, and the opening part is provided on the wall surface formed of a mold split part or the wall surface formed of an integral mold part. According to the above constitution, even when a forging material, which has gone into the venting passage, is broken in the discharge of the product, in the next forging, the material is pushed to the next state by gas pressure. Thus, there is no possibility that the venting passage is clogged. Accordingly, even when the shape of the mold is complicated, gas confined within the molding hole can be allowed to escape smoothly, and, thus, a forged product with good dimensional accuracy in which the occurrence of underfill has been suppressed, can be produced.</p> |
