The casting tips and nozzle, vacuum-formed headbox and tundish are the key factors to ensure aluminum coil casting and rolling production.
After lowering the vacuum-formed headbox and tundish (also called front box) temperature, the coarse grain defects caused by the excessive temperature can be reduced, the oxidation slagging reaction of the melt at high temperature can be reduced, and the quality of the cast-rolled plate can be ensured.
Due to the increase of the casting speed, the second phase size in the high magnification structure of the cast-rolled coil is smaller, dispersed, and distributed more uniformly. The fine intermediate metal compound particles can improve the mechanical properties of the material, and they can increase the strength of the material without reducing its plasticity.
Due to the increase of the casting-rolling speed, the melt solidification conditions are improved, the internal structure density of the cast-rolled coil is increased, and the internal structure quality is significantly improved. However, the increase in casting-rolling speed is also limited to a certain range. As the vertical height of the alloy crystallization interval increases, the casting-rolling speed should be reduced accordingly.
In order to cope with the cooling and speed increase of the casting and rolling, based on the increase of the nozzle roll gap, the nozzle flow distribution method must be improved, and the temperature uniformity and fluid pressure uniformity of the nozzle cavity must be improved by improving the distribution of the blocking blocks in the caster tips. In order to coordinate with the cooling and speed-up of casting and rolling, the cooling intensity must be increased to ensure the heat balance in production.
Lowering the headbox and tundish temperature and increasing the casting speed can not only increase production efficiency, but also improve melt fluidity and melt solidification conditions, and increase the density of the internal structure of the cast-rolled coil.