Mold device and method of manufacturing cylinder block

A method of manufacturing a cylinder block with a die apparatus comprising a split core assembly inserted into a cavity in a casing die for forming a columnar hole in a casing, said split core assembly including a plurality of first and second split cores, a distal end core, an inner core having a longitudinal axis, and a second stopper, wherein said columnar hole comprises a bore in the cylinder block, said method comprising:

• a first step of abutting said first and second split cores against an upper surface of said distal end core, said upper surface being located opposite said inner core:
• a second step of introducing a molten metal into said cavity;
• a third step of withdrawing said inner core, causing first and second engaging members to move, respectively, into first and second engaging grooves, moving said first split cores and said second split cores toward said axis, and releasing said first split cores and said second split cores from a formed product made of the solidified molten metal;
• a fourth step of removing said split core assembly from said formed product to form said bore;
• and
• a fifth step of cuffing an inner surface of said bore.