A proprietary process is disclosed for the direct casting of non-ferrous alloy sheet for architectural panels, foils, automobile body panels, and beverage cans from molten metal to eliminate many of the problems associated with adapting the conventional slab casting process to sheet casting. With bottling companies now casting their own sheetstock for beverage cans rather than relying on dedicated slab casting companies, it would be equally advantageous for automobile companies projecting the use of aluminum alloy car panels to follow suit. However sheet-casting processes now entering production or being seriously considered for full commercial production suffer from several shortcoming that diminish their economic viability.
The drum casting machines in operation or development have limited production capability arising from very limited contact area between the molten metal and the cooling drums. Moreover drum machines suffer from spanwise sheet gauge variations that require elaborate baffling plates in the tundish for liquid metal distribution. Such baffling restricts the flexibility of the process in terms of sheet thickness and casting rate, changes in which require changes in the baffling system.
The belt casting machines are highly complex, requiring continual adjustments for satisfactory operation, and are seriously limited in plate width. In light of these limitations an alternative sheet casting apparatus is disclosed wherein metal is cast on a pinched pair of rotating drums under automated spanwise-stage temperature control. Because the proprietary Quad-Cast Continuous Casting process exhibits the simplicity of the drum casting machines and the uniform cooling capability of the chill-block belt process, diverse alloys can be cast. Circulating liquid metal in the Quad-Cast Continuous Casting machine promotes alloy uniformity.
Because two streams of sheet are cast simultaneously with the Quad-Cast Continuous Casting machine compared to ordinary drum and belting casing machines, significantly higher casting rates are practical in essentially the same size installation.
The maximum width of the of non-ferrous sheet produced by the Quad-Cast Continuous Casting machine is limited only by liquid metal supply and distribution requirements inasmuch as the several temperature control stages integral to the PDDC machine will provide sheet gauge uniformity within required limits. Accordingly process control is essentially independent of sheet width.