In the casting process of nozzle brick, the molten steel flow is controlled in the following ways:

I. Coordination of nozzle brick and plug brick

The nozzle brick is in line contact with the plug brick. When not pouring, the plug brick is tightly inserted into the runner of the nozzle brick to ensure that the molten steel will not leak. When pouring is needed, the plug brick is pulled out by mechanical device or manual operation, and the molten steel flows out from the runner of the nozzle brick. This design can effectively control the opening and closing of molten steel.

II. Structural design of nozzle brick

The upper opening of the nozzle brick is arc-shaped, which is convenient for the insertion and extraction of the plug brick and reduces the resistance of molten steel flow. The lower section is a straight section, which is helpful to stabilize the flow rate of molten steel and ensure the stability of pouring process.

III. Size control of nozzle brick

The inner diameter of nozzle brick directly affects the flow and velocity of molten steel. According to the volume of steel bucket, pouring method and steel grade, the diameter of nozzle can be selected within the range of 20 to 120 mm. For example:

When the ladle capacity is constant and the spindle size or the number of spindles per plate increases, the nozzle diameter needs to be increased accordingly.

When the spindle size and the number of spindles per plate remain unchanged, but the ladle capacity increases, the nozzle diameter needs to be reduced appropriately.

IV. slide gate system (for continuous casting)

In the process of continuous casting, the slide gate system adjusts the molten steel flow through the sliding of the upper and lower slabs. Slide gate system can accurately control the flow of molten steel from ladle into tundish, so that the inflow and outflow of molten steel can reach a balance, thus achieving stable continuous casting operation.

V. Use of drainage agents

In some pouring processes, drainage agent (such as drainage sand) will be filled in the nozzle brick to help the molten steel flow out smoothly. The drainage agent should have good fluidity and corrosion resistance to prevent molten steel from condensation or blockage in the nozzle.

VI. Electromagnetic field control technology (advanced application)

In some advanced continuous casting processes, electromagnetic field technology is used to control the flow of molten steel in the nozzle. By installing an electromagnetic stirring device outside the nozzle, the molten steel forms a rotating flow in the nozzle, thus reducing the impact strength of the molten steel on the billet and improving the temperature distribution of the molten steel.

Through the above methods, the nozzle brick can effectively control the flow of molten steel in the casting process, ensuring the smooth casting process and the stability of casting quality.