Abstract: A mold sand feeding tank 4 is provided for feeding mold sand S into a hollow core molding portion 2 defined by a pair of molds 1a and 1b mating with each other. A switching valve 7 is disposed within the mold sand feeding tank 4 and has a mold sand feeding opening 5, through which the mold sand S is fed into the mold sand feeding tank 4 from the outside, and a mold sand discharging opening 6, through which non-hardened mold sand Sb within the hollow core molding portion 2 is directly and externally discharged.

Abstract: The apparatus includes a casting core forming die, a mold sand feeder with an opening, a mold sand tank, a suspension device for lifting and for lowering the mold sand tank, supporter and mover for the mold sand tank between a first position where it can be charged with mold sand, and a second position where the mold sand is to be transferred to the casting core forming die, a device for weighing the mold sand tank when it is lowered onto the supporter and mover, and an opener and closer for the opening of the mold sand feeder upon the weighing device emitting a signal.