PURPOSE: To decrease the generation of cracks in inter-valve parts, etc., by removing chillers from a casting mold and allowing spheroidal or mass graphite to precipitate when the temp. of a rough shape material for a cylinder head cools down to a specific temp.
CONSTITUTION: The chillers 4 are installed to the parts of the casting mold corresponding to the respective surfaces in the inter-valve parts 10 between suction valves and exhaust valves as well as parts 11 between the suction valve and chamber and the parts 12 between the exhaust valves and chamber of the cylinder head. The chillers 4 are removed from the casting mold when the temp. of the rough shape material for the cylinder head decreases to 1,000W1,050°C on solidifying of the molten metal after pouring. The casting is rested as it is to decompose the cementite and to allow the spheroidal graphite or mass graphite to precipitate. The generation of the cracks in the inter- valve parts, etc., is thereby decreased.
KOYAMA HARATSUGU
KANAZAWA TAKAAKI
