PURPOSE: To surely fill up molten metal into thin thickness of a radiating part by filling up molten metal under pressurizing while exhausting gas at inner part under negative pressure condition in a mold.
CONSTITUTION: The mold 1 is inserted in a vacuum sucking case 8 and the negative pressure is applied to exhaust the air in a cavity. At the same time, the pressure in the pressurizing chamber 6 is pressurized to a few atm. through compressed air, etc., from a piping 10 for pressurizing and the molten metal 13 in a crucible 5 with force by pressurizing is filled up in a gap part and hollow of the mold 1 through a stoke 12. Then, after the molten metal 13 solidifies by returning the pressure, the mold 1 is taken out of a casting apparatus 9, to remove the molding material. By this method, the surface is surrounded around the snaked heat transfer tube and a heat exchanger integratively forming the radiating part having continual hollow, which fine wire-like fins show skeleton-like on the outer side, is obtd.
AZUMA KAZUO
HIROSE YOSHIOKI
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