Two wheel melt overflow process and apparatus

#This invention relates to a process and accompanying apparatus for producing film or sheet of finely controlled thickness and microstructure, and more particularly relates to a process and apparatus for producing a wide variety of such materials directly from a molten material, such as metals, polymers and ceramics. The process initially moves the surface of a cooling, rotating roll past a region of contact with the molten material to form a rapidly solidifying layer of the material thereon, then cools the layer and passes it into a kissing region where it contacts a second, oppositely rotating upper roll which may contain a chilled, solidifying layer. The resultant pressing forms a unitary or fused product film or sheet which is removed from the apparatus.

#The prior art discloses a variety of methods and apparatus which can produce solid material directly from a source of molten material. Many of these prior art systems are for the fabrication of metal products and use some type of fixed, rigid, noncontrollable forming orifice to stabilize the dimensions of the product. Additionally, the prior art utilizes a wide variety of two wheel systems that form a kissing zone as they rotate in opposite directions.

#With respect to two wheel systems which form a finished product, the Bessemer U.S. Pat. No. 49,053, discloses the basic, concept behind a majority of the systems that are currently utilized. Bessemer manufactures sheets, plates and the like directly from fluid malleable iron or steel by utilizing a pair of rolls, with their axes in a horizontal, parallel position to form a kissing zone. The molten metal is poured into this kissing zone, or thin space between the rolls, which are constantly moving during the flow of the metal between them. The cool surfaces of the rolls rapidly solidify the metal and the pressure of the rolls forms a metal product. However, as one would expect from such an early setup, there are many difficulties present in the system of Bessemer, particularly with respect to their utilization of a fixed sized crucible.

#FIGS. 1-3 are simplified diagrams of three respective embodiments of the invention, each having a different position of the upper rotating roll in relationship to the surface of the molten material present in the tundish.

#FIG. 4 is a close-up section of molten and frozen material flowing into the kissing zone between the two rolls.

#FIG. 5 sets forth a cross sectional view of a film product produced by at least partially freezing material on each roll surface and fusing the two films together.

#FIG. 1 illustrates a receptacle, or tundish 10 which is heated in a conventional manner and contains a pool of molten material 12 which can be supplied by a variety of methods, such as from furnace 14. However, instead of the walls of receptacle 10 everywhere extending above the upper surface 16 of the molten material 12, a portion of the receptacle wall is absent in the region above a generally horizontal edge 18 which is formed at the top of a portion of the wall of the receptacle 10. A particularly suitable receptacle for depositing thin, molten substrates on rotating surfaces and the like is set forth in copending application Ser. No. 89,544 filed Aug. 26, 1987 and now U.S. Pat. No. 4,831,472, the disclosure of which is incorporated by reference.

#Edge 18 is lower than the top of the other walls of the receptacle so that the molten material level may be raised sufficiently to overflow over the edge 18 and onto a peripheral surface of a lower cylindrical heat extracting substrate, i.e., a rotating wheel or roll 20 which is rotated about its pivot axis 22. The cooling roll 20 is spaced a fixed distance from the edge 18 and is preferably vertically and horizontally adjustable relative to the edge during periods of non apparatus operation so as to permit the spacing from the edge to be controllably varied and also to permit adjustment of the angular position about the roll 20 at which the molten material melt or film 24 contacts the surface 26 of roll 20.

#A conventional means such as an electrical motor and connecting drive means (both not shown) are provided for driving the surface 26 of the roll 20 past the region of its contact with the melt 16. In most applications it is driven at a surface speed in the range of 0.1 to 5.0 meters/sec.