CONTINUOUS CASTING METHOD FOR HOLLOW BILLET

摘要

PURPOSE:To prevent the intrusion of an oxide film into a molten metal and the leakage of the molten metal and to continuously cast a hollow billet having good quality by specifying the difference in top surface height between an outside water-cooled casting mold which is disposed to a molten metal receiving tank and has a specific inside diameter or below and inside water-cooled mandrel within a specific range. CONSTITUTION:The outside water-cooled casting mold 1 having <=300mm inside diameter is provided to the bottom surface of a heat-resistant outside wall 3a of the heat- resistant molten metal receiving tank 3 provided with a molten metal supply spout 4 and the inside water cooled mandrel 2 is disposed to the bottom surface to a heat resistant inside wall 3b at the center. The intrusion of the oxide film on the surface of the molten metal 9 into the molten metal is thoroughly prevented in this case even if the mandrel is not oscillated. The difference Ha-Hb in the top surface height between the outside and inside casting molds 1 and 2 is kept within a >=-5mm-<=20mm range. The balance in the formation of inside and outside solidified shells 10b, 10b is improved and the possibility of the molten metal leakage is eliminated. The hollow billet 10 having the good quality is thus stably and continuously case even without the conventional oscillating device.