Chill moulding process, particularly for metals, and apparatus and mold for use therein

A molding method to produce a molded piece of a material of high melting point, comprising the steps of:

• forming a bath of molten material;
• bringing an upper end of a channel, having an internal conduit provided with a constriction at said upper end, into releasable leak-tight fluid communication with an aperture of a mold cavity provided in a mold;
• blowing an inert gas into said mold cavity while a lower end of the channel is above the bath;
• lowering the lower end of the channel while maintaining said blowing until the lower end of the channel is immersed in the bath, the escape of inert gas through the conduit of the channel being thus at least retarded by this immersion;
• meanwhile, detecting a parameter such as the inert gas pressure or flow rate, on which retardation of escape via the channel has an influence and comparing said parameter with a known value at which escape retardation occurs and, when said detected value equals said known value, drawing a vacuum in the mold cavity for aspirating the fused material into the mold cavity upon detection of said retardation until said mold cavity is substantially filled;
• allowing the material to solidify in the constriction;
• lifting up said mold and said channel so as to move said lower end of said channel out of said bath;
• spacing apart said mold and said channel so as to rupture in tension solidified material in said constriction;
• allowing material remaining in said channel to return into said bath of molten material;
• and
• demolding said molded piece by separating the mold into plural portions.

A molding apparatus comprising:

• a container for a bath of molten material;
• a mold provided with an internal mold cavity and comprising plural separable portions;
• a channel made of a highly heat-conductive material and having an internal conduit, said conduit being provided with a constriction at an upper end of said channel and said upper end being adapted to be brought into releasable leak-tight fluid communication with an aperture of said mold cavity through a lower face of said mold;
• means for bringing the upper end of said channel into releasable leak-tight fluid communication with said aperture of the mold and for forcibly separating the channel from the mold;
• means for immersing a lower end of said channel in said bath and for raising said lower end out of the bath;
• and
• means for separating the mold into said plural portions.

A molding apparatus comprising:

• a container for a bath of molten material;
• a mold comprising at least two mold halves defining a mold cavity between themselves and separably applied against each other on a mating surface which in operation is substantially vertical;
• a channel having an internal conduit, said conduit being provided with a constriction at an upper end of said channel, and said upper end being adapted to be brought into releasable leak-tight fluid communication with an aperture of said mold cavity through a lower face of said mold, by means of an annular joint surrounding the constricted end of the conduit of the channel;
• between said two mold halves, a joint in the form of a closed loop disposed in a U about the mold cavity so as to be capable of sealed contact of the two ends of the U with said annular joint surrounding the constricted end of the conduit of the channel;
• means for bringing the upper end of said channel into releasable leak-tight fluid communication with said aperture of the mold and for forcibly separating the channel relative to the mold;
• means for immersing a lower end of said channel in said bath and for raising said lower end out of the bath;
• and
• means for separating the mold into said mold halves.