To obtain an as-cast product without developing shrinkage hole and blow hole with feeding head effect, to save molten metal quantity and to reduce the boring time by standing a core composed of a sintered body of refractory powder having low thermal conductivity in the center of a metallic mold, completing the molding and pouring molten metal.
On a molding board 1, the metallic mold 2 having the inside shape regulating the outside of the product, is put. In the inner part of the metallic mold 2, the core 3 composed of the one sintering the refractory powder and shaped as a bar or a pipe having smaller diameter than that of a planned through-hole in the inner part of the product is stood and them a sleeve 4 for feeder head is prepared. The molten metal (6) is poured into the prepared mold and cooled under condition of progressing the solidification toward the center from the outside in the metallic mold 2 while obtaining the feeder head effect to obtain the metallic as-cast product holding the core 3. To this as-cast product, the through-hole formed with the core 3 is machined to obtain a prescribed size of a hollow metallic product. At the time of standing the core 3 in the metallic mold 2, a core standing molding board 5 having the hole matching to the outer diameter of the core 3 is laid on the molding board 1.
YAGI YUTAKA
OYA KOJI
