PURPOSE: To eliminate the need of a special process in a casting method by executing the pulling-out of a core in a trimming process, at the time of casting a product by press-charging molten metal into a cavity inserted with the core at high pressure.
CONSTITUTION: The core (n) maintains a prescribed strength during a time since the molten metal is press-charged into the cavity until the part of the molten metal in contact with the core is solidified (characteristic of the molten metal A), i.e., during a time of T1, and even if the high pressure of the molten metal is applied to the core (n), the core is not deformed to such an extent that shape precision becomes lower than that required for the product X (characteristic of the core G1). Further, the average strength of the core (n) is lowered by the heat of the molten metal during the lapse of a time of T2 after the molten metal is solidified at the part in contact with the core (n) (after the lapse of a time of T1), the plastic deformation of the core is generated to such an extent that the core (n) can pass through an under-cut part of the product X and yet the mutual coupling force, by which one end can be pulled out by pulling out the other end, is imparted. Therefore, the core can satisfactorily be pulled out of the product by giving the pulling force to the core at the suitable timing during th lapse of a time of T2 after the lapse of a time of T1.
OKADA YUJI
SHIRAKAWA HIROICHI
TOMITAKA SHUICHI
MURAKAMI KOJI
