Metal level overshoot or undershoot mitigation at transition of flow rate demand

Patent metadata

Field	Value
Publication number	US-10632528-B2
Application number	US-201816190761-A
Country	US
Kind code	B2
Filing date	Nov 14, 2018
Priority date	Nov 15, 2017
Publication date	Apr 28, 2020
Grant date	Apr 28, 2020

Abstract

Automated processes and systems dynamically control the delivery rate of molten metal to a mold during a casting process. Such automated processes and systems can include automatically controlling a flow control device (such as a control pin) during a first phase of casting to modulate molten metal flow or flow rate, moving the flow control device in a transition time between the first phase and a second phase toward a substitute flow control device position determined based on a difference between a first projected flow rate of the first phase and a second projected flow rate of the second phase, and resuming automatic control of the flow control device during the second phase based on the detected metal level and the metal level setpoint. Overshoot and/or undershoot can additionally or alternatively be mitigated by translating the mold or altering the cast speed.

First claim

That which is claimed is:

1. An apparatus for casting metal, the apparatus comprising:
a mold;
a conduit configured to deliver molten metal to the mold, the conduit controllably occluded by a flow control device;
a positioner coupled to the flow control device;
a level sensor configured to sense a level of the molten metal in the mold; and
a controller comprising a processor adapted to execute code stored on a non-transitory computer-readable medium in a memory of the controller, the controller being programmed by the code to:
accept or determine input in the form of a metal level setpoint that is variable over time according to a casting recipe having at least a first phase, a transition time, and a second phase, wherein the first phase has a first projected flow rate that differs from a second projected flow rate of the second phase, and wherein the transition time corresponds to a time between an end of the first phase and a beginning of the second phase;
accept input from the level sensor in the form of a detected metal level; and
provide a transition command signal configured to achieve a goal of reducing or eliminating an amount of undershoot or overshoot related to the transition time, the transition command signal configured to achieve the goal by causing at least one of:
(A) movement of the flow control device in the transition time toward a substitute flow control device position determined based on a difference between the first projected flow rate of the first phase and the second projected flow rate of the second phase;
(B) translation of the mold to change a height between the mold and the conduit; or
(C) alteration of a casting speed at or adjacent the transition time to differ from during the second phase.

2. The apparatus according to claim 1 , wherein the transition command signal is configured to achieve the goal by causing (A), (B), and (C).

3. The apparatus according to claim 1 , wherein the transition command signal is configured to achieve the goal by causing (A) without also causing (B) and without also causing (C).

4. The apparatus according to claim 1 , wherein the transition command signal is configured to achieve the goal by causing (B) without also causing (A) and without also causing (C).

5. The apparatus according to claim 1 , wherein the transition command signal is configured to achieve the goal by causing (C) without also causing (A) and without also causing (B).

6. The apparatus according to claim 1 , wherein the controller is programmed by the code to further:
provide to the positioner, a first command signal that automatically controls the flow control device during the first phase to modulate flow or flow rate of molten metal through the conduit based on the detected metal level and the metal level setpoint such that the level of molten metal in the mold remains in a molten metal level range having endpoints on either side of the metal level setpoint;
wherein the transition command signal is configured to achieve the goal by at least causing (A) so as to cause the movement of the flow control device in the transition time toward the substitute flow control device position determined based on the difference between the first projected flow rate of the first phase and the second projected flow rate of the second phase; and
provide to the positioner, a second command signal that automatically controls the flow control device during the second phase based on the detected metal level and the metal level setpoint.

7. The apparatus according to claim 1 , wherein the transition command signal is configured to achieve the goal by at least causing (A), wherein the controller is programmed by the code to further determine the substitute flow control device position based on a difference between the first projected flow rate of the first phase and the second projected flow rate of the second phase.

8. The apparatus according to claim 7 , wherein the controller being programmed by the code to further determine the substitute flow control device position based on the difference between the first projected flow rate of the first phase and the second projected flow rate of the second phase comprises:
determining, by the controller, a difference value between the first projected flow rate of the first phase and the second projected flow rate of the second phase; and
determining the substitute flow control device position by modifying a flow control device position at or adjacent the end of the first phase according to a linear relationship with the difference value.

9. The apparatus according to claim 1 , wherein the transition command signal is configured to achieve the goal by at least causing (A), wherein the controller is a proportional-integral-derivative (PID) controller that includes a PID algorithm for casting of the metal.

10. The apparatus according to claim 1 , wherein the transition command signal is configured to achieve the goal by at least causing (B), wherein the apparatus further comprises one or more actuators coupled with the mold and configured to at least one of raise or lower the mold relative to the conduit.

11. The apparatus according to claim 1 , wherein the transition command signal is configured to achieve the goal by at least causing (B), wherein the translation of the mold comprises raising the mold to reduce a height between the mold and the conduit so as to mitigate overshoot.

12. The apparatus according to claim 1 , wherein the transition command signal is configured to achieve the goal by at least causing (B), wherein a rate or amount of translation of the mold is determined based on a difference value between the first projected flow rate of the first phase and the second projected flow rate of the second phase.

13. The apparatus according to claim 1 , wherein the transition command signal is configured to achieve the goal by at least causing (B), wherein a rate or amount of translation of the mold is determined based on a difference value between the detected metal level and the metal level setpoint.

14. The apparatus according to claim 1 , wherein the transition command signal is configured to achieve the goal by at least causing (C), wherein the apparatus further comprises a bottom block configured for (i) movement downward from the conduit and (ii) for supporting an ingot formed by the molten metal delivered to the mold, wherein the casting speed comprises a rate at which the bottom block moves downward from the conduit.

15. The apparatus according to claim 1 , wherein the transition command signal is configured to achieve the goal by at least causing (C), wherein alteration of a casting speed during the transition time comprises causing the casting speed at or adjacent the transition time to be greater than during the second phase so as to mitigate overshoot.

16. The apparatus according to claim 1 , wherein the transition command signal is configured to achieve the goal by at least causing (C), wherein the amount of alteration of the casting speed is determined based on a difference value between the first projected flow rate of the first phase and the second projected flow rate of the second phase.

17. The apparatus according to claim 1 , wherein the transition command signal is configured to achieve the goal by at least causing (C), wherein the amount of alteration of the casting speed is determined based on a difference value between the detected metal level and the metal level setpoint.

18. The apparatus according to claim 1 , wherein the first projected flow rate of the first phase is

Assignees

• Novelis Inc

Inventors

• Sinden Aaron David
• Mccallum John Robert Buster
• Wagstaff Robert Bruce

Classifications

• B22D11/18

  for pouring (B22D11/20 takes precedence) · CPC title

• B22D11/201

  responsive to molten metal level or slag level · CPC title

• B22D11/181 Primary

  responsive to molten metal level or slag level · CPC title

• B22D11/103

  Distributing the molten metal, e.g. using runners, floats, distributors · CPC title