PURPOSE: To easily cope with the alteration, etc., of a passage shape by sticking plural shell plates formed in cross sectional shape of the passage and laminating.
CONSTITUTION: By using a core for casting, the passage is formed in a cast- formed material. This core is formed by sticking plural shell plates 14a-14e formed in cross sectional shape of the passage. A gas venting passage is formed near the stuck surface of one side stuck shell plate. A projecting part 17 fitted to a part of the degassing passage 15 is formed at the stuck surface side of the other shell plate. By superposing plural pieces of the shell base plates formed in thin plate state, the shell plate cut as the cross sectional shape of the passage is formed and each shell plate is stuck. By this method, the core mold is unnecessitated and the cost can be lowered.
MORITA TOSHIJI
NAKADA YASUSHI