| 摘要 |
<p>PURPOSE:To easily process a cast product by applying annealing after casting to part for executing the processing of the cast product, which is cast by using a metallic mold, and softening. CONSTITUTION:By pouring molten iron composed of cast iron component corresponding to JIS FC20-FC30 into the metallic mold, a cam shaft 1 is cast, and at the time when the molten iron surface layer part 1a in contact with the metallic mold becomes shell-state solidified layer having high hardness chilled structure, the casting is released from the metallic mold. Under red heat condition (about 600-900 deg.C) of the cam shaft 1 released from the metallic mold, a journal part 3 as the necessary softening part is rapidly heated to about 1000-1100 deg.C with a high frequency heating member 4 and held for about 20-30sec. At this time, the temp. of part except the journal part 3 is the temp. of A1 transformation point or lower. Successively, the cam shaft 1 is naturally cooled, and after lowering the temp. to near the room temp., the whole cam shaft 1 is reheated in a furnace at about 550-600 deg.C execute the annealing for relieving casting stress. By this method, only the journal part 3 can be softened.</p> |
