Kawasaki Steel Corporation

Takesaburo Nishioka

Takemi Yamamoto

Jun-ichi Matsuno

Kazuo Aso

Naomichi Miyai

The casting apparatus for a hollow steel ingot is constructed such that: at least three concentric pipes are provided in the central portion of an ordinary mold for a steel ingot; a core is formed by filling up a space formed between the first outer-most pipe having the largest diameter and the second pipe disposed inwardly of the first pipe with granular refractory material wherein zircon or chromite sand is bound by a binder such as an organic resin; a double pipe is disposed inwardly of said core and forming a gas flow course for cooling the core; and pouring gates formed through the stool for feeding molten steel at an intermediate portion between the inner wall of said mold and the core. The method for producing a hollow steel ingot by use of the casting apparatus as described above comprises: blowing the cooling gas from above into the third inner-most pipe having the least diameter, passing the gas through the second pipe from below and discharging it to above; cooling the molten steel fed into the mold and brought into contact with the outer surface of the first pipe by cooling the core through the inner wall of the second pipe; and controlling the cooling conditions for the core such as the thickness of the cylindrical refractory material of the core, the cross-sectional area of the cooling gas flow course and the thickness of the second pipe so that the finally solidifying position of the molten steel fed can be set at a position which is apart from the core side at a distance of 20 to 50% of the wall thickness of the hollow steel ingot to be formed.

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Tokyo, Japan

Takesaburo Nishioka