| 摘要 |
PROBLEM TO BE SOLVED: To obtain an absolutely new iron-made cam shaft having a fine hole for supplying lubricating oil onto a chilled cam surface and a journal surface by setting chillers inserting a fine shell bar into a hole in the chilled part to the cam position in a master mold, laying a center core, burning or carburizing the shell bar inserted at casting time and grinding it off with fine shot balls. SOLUTION: Upper mold and lower mold chillers 1, 2 are set in a shell mold 3 and the shell bar 5 is inserted into the chiller hole 4 opened in the chiller and the shell center core 6 is laid. After casting, the inserted shell bar 5 is burnt with the oxygen in the air and the heat at casting time, and the burnt shell is ground off with the fine steel balls (<=0.7 mm diameter) at the casting finish time. The casting can be executed while inserting the fine shell bar into the center core or into the shell bar integrally with the center core. On the other way, the shell bar is inserted into the holes in the cam and the journal part in the master mold and the non-chilled solid material is bored and further, after surface-hardening, the shell bar can be ground off and removed.
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