Apparatus for unidirectionally solidifying metals

Claim 2

In combination: a. first and second annular heat pipes joined together in close end-to-end spaced apart adjacency and having central passageways substantially aligned along a common axis; b. means including first and second heater means coupled separately to said first and second heat pipes respectively for establishing isothermal conditions in said heat pipes along said axis, with said first heat pipe at a higher equilibrium temperature than said second heat pipe, thereby to establish along said axis a temperature profile characterized by a step function; c. means for supporting a workpiece within the central passageway defined by said first heat pipe; d. means providing relative motion between said workpiece and said heat pipes along said axis so as to cause said workpiece to move out of the passageway of said first heat pipe into the passageway of said second heat pipe, thereby causing a thermal gradient represented by said step function to traverse the length of said workpiece; and e. cooling means coupling to said second heat pipe at a location spaced longitudinally from said second heater means and controllable to remove excess heat from said workpiece when the workpiece is within the working space of said second heat pipe, thereby to minimize any reduction in the magnitude of said thermal gradient.

Claim 3

The invention according to claim 1, wherein said heat pipes are provided with different working fluids having differing vaporizing temperatures; and further wherein said heater means comprise means for heating said heat pipes to the vaporizing temperatures of their respective working fluids.

Claim 4

The invention according to claim 2, and further including means for cooling said workpiece by conduction in a direction along said axis.

Claim 5

Metal casting apparatus, comprising: a. a first annular heat pipe having a central tubular working space arranged along a longitudinal axis and provided with means for establishing and maintaining in said first heat pipe a uniform temperature above the liquidus temperature of a desired alloy to be solidified from the molten state; b. a second annular heat pipe joined with said first heat pipe in close end-to-end spaced apart adjacency and having a central tubular working space aligned along said longitudinal axis and provided with means including heater means for establishing and maintaining in said second heat pipe a uniform temperature below the solidus temperature of said desired alloy to thereby establish a sharp thermal gradient at the junction of said heat pipes; c. a mold disposed within the working space of said first annular heat pipe for receiving a charge of said alloy in liquid form; d. means for extracting heat from a portion of said mold along a direction parallel to said longitudinal axis; e. means for providing relative motion between said mold and said heat pipes to cause said mold to move from one working space to the other and thereby cause the junction where said thermal gradient occurs to traverse said mold from a position adjacent to said heat extracting means to the opposite end thereof in a direction along said longitudinal axis; and f. cooling means coupled to said second annular heat pipe at a location spaced longitudinally from said heater means and controllable to remove excess heat from said mold when said mold is within the working space of said second annular heat pipe, thereby to maintain said second annular heat pipe below the solidus temperature of said alloy and thereby minimize any reduction in the magnitude of said thermal gradient.

Claim 6

Metal casting apparatus, comprising: a. a first annular heat pipe having a central tubular working space arranged along a longitudinal axis and provided with means for establishing and maintaining in said first heat pipe a uniform temperature above the liquidus temperature of a desired alloy to be solidified from the molten state; b. a second annular heat pipe joined with said first heat pipe in close end-to-end spaced apart adjacency and having a central tubular working space aligned along said longitudinal axis and provided with means including heater means for establishing and maintaining in said second heat pipe a uniform temperature below the solidus temperature of said desired alloy to thereby establish a sharp thermal gradient at the junction of said heat pipes; c. a mold disposed within the working space of said first annular heat pipe for receiving a charge of said alloy in liquid form; d. means for extracting heat from a portion of said mold along a direction parallel to said longitudinal axis; e. means for providing relative motion between said mold and said heat pipes to cause said mold to move from one working space to the other and thereby cause the junction where said thermal gradient occurs to traverse said mold from a position adjacent to said heat extracting means to the opposite end thereof in a direction along said longitudinal axis; and f. cooling means coupled to said second annular heat pipe at a location spaced longitudinally from said heater means and controllable to remove excess heat from said mold when said mold is within the working space of said second annular heat pipe, thereby to maintain said second annular heat pipe below the solidus temperature of said alloy and thereby minimize any reduction in the magnitude of said thermal gradient.

Claim 7

The invention according to claim 4, wherein said heat pipes are provided with different working fluids having differing operating temperatures, and further including additional heater means for heating said first heat pipe to the operating temperature of its respective working fluid.

Claim 8

The invention according to claim 5, wherein said heater means comprises an electrical coil wound around a portion of each of said heat pipes respectively.

Claim 9

The invention according to claim 6, wherein said heat extracting means comprises a chill block upon which said mold is supported.

Claim 10

The invention according to claim 4 wherein said cooling means comprises a tube coiled around a portion of said second heat pipe, and further including means for causing coolant fluid to flow through said coiled tube.