The tundish stopper mechanism is a critical piece of equipment in the continuous casting process, primarily used to control the flow of molten steel from the tundish to the mold, directly impacting ingot quality and production safety. Its core functions include:

1. Precision Control of Molten Steel Flow
   Core Function: Dynamically adjusts the molten steel flow rate to match the mold casting speed by adjusting the gap between the stopper head and the tundish nozzle.
   Technical Key Points: Responds to casting speed changes (e.g., fine-tuning of ±0.1 m/min) while maintaining a constant molten steel level (molten steel level fluctuation is controlled within ±2 mm).

2. Start and Stop Operations
   During the start phase: Slowly raise the stopper to avoid turbulence or splashing, ensuring a smooth start of casting.
   During the stop phase: Rapidly and tightly close the flow channel to prevent residual steel or oxidation.

3. Emergency Safety Shutoff
   Breakout Protection: In the event of a sudden breakout or abnormal mold level, the stopper rapidly descends within 0.5-1 second to shut off the steel flow. Power Failure Emergency: Some designs are equipped with gravity/spring failure protection mechanisms to ensure automatic closure in the event of a power outage.

4. Preventing Secondary Oxidation and Slag Entrainment
   Sealing Function: The tight fit between the stopper and the nozzle minimizes contact between the molten steel and air, reducing oxide inclusions.
   Flow Field Optimization: By controlling the steel flow pattern, the tundish slag layer is prevented from being drawn into the mold (e.g., preventing the “eddy current effect”).

5. Protective Submerged Nozzle (SEN)
   Synergy: Works with the SEN to create a stable flow stream, reducing the deposition of inclusions such as Al2O3 on the nozzle wall.
   Anti-Blocking: Proper flow control can reduce nozzle nodule formation (especially with aluminum-killed steel).

6. Process Flexibility and Adaptability
   Adaptability to Multiple Steel Grades: By adjusting the stopper opening, the viscosity and oxidation characteristics of different steel grades, such as high-carbon and low-carbon steels and stainless steels, can be adjusted.
   Handling Non-Steady-State Conditions: During ladle changes or speed reductions, the stopper must quickly compensate for flow fluctuations.

The stopper mechanism is essentially the “molten steel on-off valve” of the continuous casting process. Its core functions revolve around safety, security, and stability, directly impacting the cleanliness, surface quality, and production continuity of the ingot. With the advancement of intelligent technology, its control logic has been upgraded from a basic PID algorithm to model predictive control (MPC), further enhancing the reliability of these functions.