Direct chill metal casting apparatus and technique

Apparatus for direct chill casting a metal comprising:

• means defining an open ended mold cavity having a discharge end adapted to have a support telescoped therein, and having an opening at the opposing end thereof whose diameter is smaller than the peripheral wall of the cavity so that the inner peripheral edge of said opposing end opening forms an overhang relatively over the peripheral wall, whereby when said opposing end opening of the cavity is continuously filled with molten metal, the mass of molten metal splays about the inner peripheral edge of the opposing end opening and forms a body of molten metal in the cavity whose cross-section has a divergent/convergent outline between the ends thereof, the intermediate continuum of which between the planes of maximum divergence and minimum convergence thereof, has a peripheral outline corresponding generally to the outline of the cavity at the peripheral wall thereof,
• means for chilling the molten metal body from points below the intermediate continuum,
• graphite or graphite-like wall defining means disposed in the peripheral wall of the cavity at a level below the overhang for surrounding the intermediate continuum of the molten metal body by a solid but fluid permeable wall section, and
• fluid delivery means for simultaneously forcing a lubricating oil and an additional fluid medium selected from the group consisting of a highly heat vaporizable liquid medium and a gaseous medium, through the fluid permeable wall section so that the oil and additional fluid medium discharge into the cavity at points on the inner peripheral surface of the wall section opposite the intermediate continuum, while the molten metal body is chilled and the mold and support are reciprocated in relation to one another endwise of the cavity to elongate the body,
• the wall of the cavity co-terminating with the overhang at the aforesaid opposing end of the cavity so that the part of the molten metal body directly adjacent the overhang is surrounded by a closed corner of the cavity, and
• the fluid thus discharged about the intermediate continuum forming an annulus of fluid tending to flow relatively away from the closed corner of the cavity toward the discharge end thereof.