| 摘要 |
PURPOSE:To obtain the exhaust port superior in adiabatic heat insulation at cheaper cost by molding foam metal into the wall of the exhaust port to form an adiabatic layer. CONSTITUTION:A plastic molding 5 is manufactured by fixing plastic balls to each other, for instance, and an intermediate molding 6 is obtained by metal-plating on its surface. The plastic molding 5 is removed from the intermediate molding 6 by calcining to obtain a cylindrical foam metal 7. At the inner side of the foam metal, a shell core 4 such as fran core made of fran resin binder is formed integrally therewith to reinforce the foam metal 7 and prevent its deformation when molding. Then, the shell core 4 is placed in a main mold and molten aluminum alloy is poured thereinto to mold a cylinder head 1, thereafter the shell core 4 being removed. There is contained an air layer within continuous air bubbles of thus molded adiabatic layer 3, so it is possible to obtain an exhaust port superior in adiabatic heat insulation. |
