PURPOSE: To surely make the bottom part of a cast billet be caught to a dummy bar chuck by forming the outer diameter at the lower part of the dummy bar chuck to the specific size and the outer diameter at the upper biting part to smaller than the outer diameter of the hollow cast billet, arranging the specific condition of the biting projections and forming the whole height higher than the height of a pouring basin part at the initial stage.
CONSTITUTION: The outer diameter at the lower part of the dummy bar 1 is made smaller than the inner diameter of the mold in an infected hollow cast billet casting apparatus by 5-10mm and the biting part is arranged at the upper part so as to surround the outer periphery, and the outer diameter of this biting part is made smaller than the outer diameter of the casting hollow cast billet and also the thickness from the apex of projections 2 to the inner diameter in the biting part is made to ≥10mm, and the height of the projection in the biting part is made ≥5mm and the number is arranged to ≥4 and the whole height is higher than the height of the molten metal pouring basin part at the initial stage in the objected hollow cast billet casting apparatus. The bottom part of the cast billet can surely be caught to the dummy bar chuck and the solidified shell is not restricted by a core before casting.
TAKEUCHI EIICHI
FUJI TAKEHIKO
