US Patent 7740049 Mold device and method of manufacturing cylinder block

A method of manufacturing a cylinder block using a die apparatus wherein a columnar hole includes a bore in the cylinder block. The method includes the steps of abutting first and second split cores against an upper surface of a distal end core, the upper surface being located opposite the inner core, and introducing a molten metal into a cavity. An inner core is withdrawn to move the first and second split cores toward an axis. The first and second split cores are released from a formed product made of solidified molten metal. The split cores are removed from the formed product to form the bore, and an inner surface of the bore is cut.