Metal founding – Process – Shaping liquid metal against a forming surface
Patent
1989-03-21
1991-01-08
Lin, Kuang Y.
Metal founding
Process
Shaping liquid metal against a forming surface
164479, 164428, B22D 1106
Patent
active
049827804
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to the continuous casting of metals into moulds with movable walls which can be of any form such as, e.g., plates, barrels, discs and strip suitable for the production of products with an unlimited length and has specific reference to methods of making metal filaments and apparatus materializing such method.
Within the scope of the present invention, the term metal filament refers to a slender body whose transverse dimensions are substantially less than its length.
Accordingly, filaments can be such bodies as ribbon, strip, sheet and wire of constant or variable cross section.
PRIOR ART
Known in the art is a method of producing metal filaments (U.S. Pat. No. 4,154,283) according whereto a metal from a molten source is continuously cast on an unceasingly moving quench surface, a metal filament is formed thereupon which is then separated from the quench surface and coiled.
The prior art method provides for producing metal filament with even edges and a specified structure, e.g. an amorphous one. In the prior art method, the metal is fed from the molten source to the movable quench surface in a continuous stream of circular or rectangular cross-sectional area at a given rate. An impact of the melt with the quench surface causes the melt to spread into a pool of a width which is greater than the diameter of the cross-sectional area of the stream, or the width thereof if the melt has a rectangular cross-sectional area.
It is known that the pool of melt retains its stability as long as the quench surface cools down and withdraws the lower layer thereof at the place of contact in the form of a formed continuous filament. Retaining its shape due to a high surface tension of the molten metal, the pool in fact rises upstream of the melt until the stable state is attained.
It is also known that the thickness of the filament so formed various directly with the length of the pool melt at the quench surface and inversely with the rate of displacement of this surface. Since the width of the metal filament so formed equals that of the pool of melt, the prior art method is suitable for forming filaments of rectangular cross-sectional area only. Filament with square cross-sectional area cannot be formed in the known way.
The casting of the filament takes place in a vacuum.
It is known that in the absence of vacuum a thin gas layer, referred to as boundary gas layer, is formed between the quench surface and the surrounding molecules of gas which are moving in this layer at a speed equalling that of the quench surface. The inherent properties of the gas layer and the way in which the layer interacts with the pool of metal, continuously extracted wherefrom and formed is the metal filament, give rise to surface irregularities at the edges of the metal filament. Only the thin gas layer which is in direct contact with the quench surface has effect on the width of the pool. A metal filament in the form of e.g. a ribbon with even edges can form only when the Reynolds number of the boundary gas layer is less than a certain critical value. Should the Reynolds number exceed the critical value, a turbulence of the gas near the pool of metal gives origin to irregular edges of the ribbon. In a vacuum, no boundary gas layer is formed and irregularities of the edges are prevented.
When a metal filament is cast in vacuum, the period of its contact with the quench surface cannot be extended by resorting to the pressure of a cooling gas flow. Sophisticated equipment is required, compared with the extracting of filament under the atmospheric pressure.
The prior art method is of no avail in producing metal filament of a constant thickness but with a width progressively decreasing with the length. As pointed out hereinabove, the width of filament is decided by the width of pool of melt and this, in its turn, is controlled by the size of the cross-section of the flow of melt, e.g. by its diameter, and the velocity of the flow. The prior art method does not permit any alteration of the cross-sectio
REFERENCES:
patent: 2886866 (1959-05-01), Wade
patent: 3881540 (1975-05-01), Kavesh
patent: 4154233 (1979-05-01), Ray et al.
Gorunov Valery E.
Kaptsevich Vyacheslav M.
Kholomeev Alexandr V.
Kostornov Anatoly G.
Lapitsky Evgeny A.
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