Method of controlling the shape of an ingot head
Systems and associated methods are provided for controlling the shape of an ingot head during formation. At the end of a cast, prior to forming the ingot head, chill bars or other cooling structure may be lowered into an ingot mold and define a reduced casting footprint for forming the ingot head. Supplemental molten metal may be fed into the reduced casting footprint, and the chill bars may be moved laterally towards the center of the ingot, further reducing the casting footprint. As additional molten metal fills the reduced mold footprint, the ingot may be lowered relative to the chill bars to further increase the height of the ingot head. Additional molten metal may be added until the desired shape of the ingot head is formed.
1. A method of ingot formation, the method comprising:
forming a base of an ingot by feeding molten metal into a mold that defines an initial casting footprint and by lowering a movable bottom relative to the mold to increase a height of the ingot;
moving at least one cooling structure at least in a vertical direction from an initial position into contact with the molten metal, wherein the at least one cooling structure is movable independent of the mold;
moving the at least one cooling structure at least in a horizontal direction within the initial casting footprint and along a top plane of the molten metal to produce a reduced casting footprint bounded at least in part by the at least one cooling structure, wherein the reduced casting footprint is smaller than the initial casting footprint; and
feeding supplemental molten metal into the reduced casting footprint to form a narrowing shape in a head of the ingot.
2. The method of claim 1 , wherein the molten metal comprises an aluminum alloy.
3. The method of claim 1 further comprising:
permitting solidification of a first region of the molten metal adjacent a first position of the at least one cooling structure relative to the head of the ingot;
moving the at least one cooling structure at least in the horizontal direction along the top plane of the molten metal to a second position relative to the head of the ingot; and,
permitting solidification of a second region of the molten metal adjacent the second position of the at least one cooling structure relative to the head of the ingot.
4. The method of claim 1 , further comprising:
permitting solidification of the molten metal; and
subsequent to the solidification of the molten metal, at least one of:
moving the at least one cooling structure at least in the horizontal direction along the top plane of the molten metal;
lowering the movable bottom; or
raising the at least one cooling structure in the vertical direction.
5. The method of claim 1 , wherein the moving of the at least one cooling structure is performed by at least one servo motor.
6. The method of claim 1 , further comprising changing an angle of the at least one cooling structure relative to the horizontal direction.
7. The method of claim 6 , wherein the changing the angle of the at least one cooling structure occurs concurrently with the moving the at least one cooling structure at least in the horizontal direction.
8. The method of claim 1 , wherein the at least one cooling structure has an angle relative to the horizontal direction, and the angle relative to the horizontal direction remains fixed while the at least one cooling structure is moving at least in the horizontal direction.
9. The method of claim 1 , further comprising routing a coolant through the at least one cooling structure.
10. The method of claim 1 , wherein the moving the at least one cooling structure at least in the horizontal direction occurs concurrently with the lowering of the movable bottom.
11. The method of claim 1 , wherein the moving the at least one cooling structure at least in the vertical direction from the initial position into contact with the molten metal comprises lowering the at least one cooling structure into a lowered position adjacent the mold and in contact with the molten metal.
12. A system for ingot formation, the system comprising:
a mold for receiving molten metal, the mold defining an initial casting footprint;
a movable bottom, movable in a vertical direction relative to the mold;
a nozzle positioned for feeding molten metal into the mold; and,
at least one cooling assembly, the at least one cooling assembly comprising:
at least one cooling structure movable independent of the mold, the at least one cooling structure movable at least in the vertical direction from an initial position into a lowered position in which the at least one cooling structure is within the initial casting footprint defined by the mold and along a top plane of the molten metal; and
an actuator coupled with the at least one cooling structure and operable to move the at least one cooling structure within the initial casting footprint and between sides of the mold at least in a lateral direction along the top plane of the molten metal so as to define a reduced casting footprint bounded at least in part by the at least one cooling structure and smaller than the initial casting footprint.
13. The system of claim 12 , wherein the at least one cooling assembly is a chill bar assembly, and wherein the at least one cooling structure comprises a chill bar.
14. The system of claim 13 , wherein the chill bar has a triangular cross-section.
15. The system of claim 12 , wherein the at least one cooling structure is positioned at an angle relative to the lateral direction.
16. The system of claim 15 , wherein the angle of the at least one cooling structure is adjustable.
17. The system of claim 12 , wherein the actuator comprises a servo motor and a ball screw.
18. The system of claim 12 , wherein the at least one cooling structure comprises at least two cooling structures, and wherein the actuator is operable to move the at least two cooling structures in the lateral direction.
19. The system of claim 12 , wherein the at least one cooling structure includes a chill bar assembly comprising:
a chill bar configured to move at least in the vertical direction to engage a molten metal surface;
a coolant conduit positioned adjacent the chill bar for conveying heat away from the chill bar when coolant is conveyed through the coolant conduit; and,
an angle adjustment base, wherein the angle adjustment base is mechanically coupled to the chill bar and configured to selectively orient the chill bar among a plurality of predetermined angles relative to a horizontal direction.
20. The system of claim 19 , wherein the angle adjustment base is lockable to secure the chill bar at a fixed angle.
21. The system of claim 19 , wherein the angle adjustment base has one or more openings arranged to engage or receive a fastener to set an angle of the chill bar.
22. The system of claim 19 , wherein the chill bar is configured to move at least in the horizontal direction within the initial casting footprint of the mold, in contact with the molten metal surface.