PURPOSE: To facilitate the formation of a curved passage by sticking the shell sand on the outer peripheral surface of a metallic cylindrical member continuously wound in spiral.
CONSTITUTION: The passage is formed in a casti-formed material by a core 1 for casting. This core 1 is formed by sticking the shell sand 4 on the outer peripheral surface of the metallic cylindrical member 2 continuously wound in a spiral shape. A core metal 3 having flexibility is inserted in the inner part of the cylindrical member 2. The cylindrical member 2 with inserted core metal is formed as the passage shape, and the shell sand is stuck as lamination on the outer peripheral surface of this cylindrical member. By this method, as gas generated during casting escapes to the outer part through this inner part from the gap of the cylindrical member 2, the degassing property is good and the casting defect is reduced.
HIRAI FUMIO
NAKADA YASUSHI
