| 摘要 |
PURPOSE:To prevent wear of a forging die and to easily obtain composite metal products by fitting a press formed metal sheet in a lower die of a forging die and putting a forging blank on the plate and forging the blank by moving an upper die down. CONSTITUTION:A steel sheet is preliminarily press formed into a holed pressed part 2 having stepped parts 2a and 2b corresponding to the shape of a formed product by a lower die 10 of a forging die and an upper peripheral edge 5. The pressed part 2 is fitted in the die 10 with the posture of the part 2 corresponding to that of the formed shape by the die 10. Next, a holed blank 11 made of an Al alloy is put on the part 2; an upper die 12 having a flat bottom surface 12a and a tapered projecting part 12b is downed to cold forge the blank 11, to fill the part 2 with the blank 11, and to form a forged part 3; the edge 5 is bent inside to engage with the above part 3. By that, the lightweight valve upper seat 1 integrally consisting of the steel sheet and the Al alloy is obtained.
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