Metallurgical apparatus – With control means responsive to sensed condition – With means responsive to condition of treated material
Patent
1991-09-10
1993-01-19
Kastler, Scott
Metallurgical apparatus
With control means responsive to sensed condition
With means responsive to condition of treated material
266236, 266276, B22D 4100
Patent
active
051805383
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to an installation for pressure casting metal products, particularly steel slabs. More precisely, it relates to the device for feeding the mould with molten metal.
The well known principle of pressure casting consists in feeding the mould with molten metal at its lower part by means of a tube in refractory material immersed in a ladle containing the molten metal which is subjected to a pressure greater than that prevailing in the mould, the latter generally being atmospheric pressure. To this end, the ladle is enclosed in a leaktight vessel fed with compressed gas. The tube passes through a removable cover for the ladle and its upper end is connected to the mould by means of a valve which is itself fixed to the mould at its lower part. Through the action of the pressure of the gas, the molten metal in the ladle is pushed into the tube and then into the mould which it progressively fills. When the mould is full, the valve is closed, thereby preventing the metal contained in the mould from flowing when, after the cast, the pressure in the vessel is reduced to atmospheric pressure. The vessel may then be displaced on a carriage towards another mould or towards a waiting area where the cover is removed from the vessel in order to permit removal of the ladle therefrom with a view to its subsequent filling with molten metal.
Installations of this type are known, in particular those in which a movable carriage forms the frame carrying the vessel. The ladle is held in the vessel on a framework bearing on the bottom of the vessel, balances being placed between the frame and the vessel with a view to continually measuring the weight of the ladle and thus of the molten metal it contains. This measurement is used, in particular, to check the quantity of molten metal remaining in the ladle during and at the end of the cast. It is, in fact, necessary to know this quantity at the end of filling a mould in order to ensure that it is sufficient to totally fill the next mould. It is, above all, necessary to check it during the cast in order to prevent the level of metal in the ladle falling below the lower end of the spout, which would enable compressed gas to enter into the spout to the detriment of the quality of the cast product and, above all, of safety, this gas being liable to cause dangerous splashes of molten metal outside the mould.
Therefore, and also due to the fact that the lower end of the spout is necessarily at a certain distance from the bottom of the ladle in order to permit the passage of the molten metal, this results in a considerable quantity of molten metal remaining in the ladle at the end of a cast, which greatly reduces the yield of the installation. It is thus desirable to reduce this remainder in the bottom of the ladle as far as possible. A known solution consists in providing, in the bottom of the ladle, a dish with a cross-section which is slightly greater than that of the spout, but markedly smaller than that of the ladle, and in extending the spout so that its lower end penetrates into the dish. Thus, the quantity of metal which has to remain in the bottom of the ladle is considerably reduced.
This solution, however, has the drawback of limiting the passage section between the spout and the dish, which causes increased erosion of the latter and of the lower end of the spout. Moreover, impurities in the metal bath and those produced by the erosion of the refractory material of the dish and of the spout consequently tend to be entrained into the mould, which is detrimental to the quality of the product cast.
Another drawback is that in order to bring the lower end of the spout closer to the bottom of the ladle, the length of the spout must be increased. The brittleness of the spout is also increased and, because it is held only at its upper part in the vessel cover, the risk of breaking it is so much greater, above all during displacements of the vessel-holder carriage or during the various handling operations of the cover carrying the spout when it is being placed
REFERENCES:
patent: 4678167 (1987-07-01), Lemper
patent: 4742994 (1988-05-01), Zannini et al.
Patent Abstracts of Japan, vol. 6, No. 190 (M-159) (1068) Sep. 29, 1982 & JP, A, 5797860, Jun. 17, 1982.
Courbier Michel F.
Vatant Robert A.
Weiss Andre
Clecim
Creusot-Loire Industrie
Kastler Scott
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