Metal founding – Process – Shaping liquid metal against a forming surface
Patent
1991-05-15
1992-01-28
Lin, Kuang Y.
Metal founding
Process
Shaping liquid metal against a forming surface
164417, B22D 1112
Patent
active
050836048
ABSTRACT:
A method for improving the internal center segregation and center porosity of a continuously cast slab, wherein an unsolidified side edge portion and a given area at the upstream side of the cast slab during continuous casting are defined as a plane reducing zone; a holding means is provided having two sets of top and bottom walking plane reducing compressing means at the plane reducing zone, front and rear supporting shafts common to the sets, eccentric cams for each set arranged at the front and the rear supporting shafts for holding and releasing of the cast slab, and a front and a rear displacement mechanism; the cast slab holding position of the upper surface of the bottom side walking plane reducing means of each set is set within 0.5 mm of the deviation on a passline of a continuous casting machine; the cast slab holding position of the lower surface of the top walking plane reducing means of each set is set at a desired reduction taper having a plane reduction ratio of 0.5 to 5.0% in accordance with an amount of solidified shrinkage of an unsolidified cast slab in a longitudinal compressing plane reducing zone and an amount of the heat shrinkage of the solidified shell; said eccentric cam set and the front and the rear displacement mechanisms are driven to operate the holding, moving forward, opening, and moving backward alternately thereby compressively carrying the cast slab; wherein the improvement comprises the steps of measuring, for each the two sets of plane reducing means the holding distance of the cast slab at before and after the top and the bottom walking plane reducing means, obtaining reduction taper from the measured holding distances and predetermined distances of distance measured positions before and after the top and the bottom walking plane reducing means, obtaining the difference between the reduction taper, then controlling positions of the front and the rear supporting shafts so that each set of walking plane reducing means is given to the desired reduction taper when the obtained difference is 0.1 mm/m or less, and bringing the walking plane reducing means having the measured reduction taper least different from the desired reduction taper close to the other measured reduction taper by changing the plane reduction ratio within a range of 0.5 to 5.0% by controlling the amount of rotation for releasing the holding of the eccentric cams, when the difference is more than 0.1 mm/m and the reduction taper are all less than said desired reduction taper.
REFERENCES:
I&SM, Jun. 1989, pp. 34 to 39, "Development of Technology To Eliminate Centerline Segregation In Continuously Cast Slabs", M. Hattori et al.
1988 Steelmaking Conference Proceedings, pp. 78 to 85, "Production of Induced Cracking (HIC) Resistant Steel by CC Soft Reduction", M. Yamada et al.
Nippon Kokan Technical Report No. 121, 1988, pp. 1 to 8, "Improvement of Centerline Segregation . . . ", T. Kitagawa et al.
Tetsu-to-Hagane, vol. 71, No. 4, Mar. 1985, S213, "Theoretical Analysis of the Fluid Flow in the Mushy Zone of CC Slab", by K. Miyazawa et al.
Tetsu-to-Hagane, vol. 71, No. 4, Mar. 1985, S212, "Effect of Soft Reduction on the Formation of V-Segregation . . . ", M. Zeze et al.
Tetsu-to-Hagane, vol. 71, No. 4, Sep. 1986, S1091, "Soft Reduction Efficiency of the Strand Near the Crater End", M. Hiyashida et al.
Transactions ISIJ, vol. 24, No. 11, Nov. 1984, pp. 883 to 890, "New Evaluation Techniques of Segregation in Continuously Cast Steel", K. Miyamura et al.
Misumi Hideyuki
Nishihara Takashi
Shirai Tokinari
Zeze Masafumi
Lin Kuang Y.
Nippon Steel Corporation
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