未分类

The material of the copper tube of the mold will affect the cooling effect.

Cooling capacity --- the cooling condition of the crystallizer reflects the heat transfer capacity of the crystallizer. If the cooling capacity of the crystallizer is strong, a large amount of heat will be carried out of the crystallizer by the cooling water, and the thickness of the shell during the initial solidification of the molten metal will increase. If the cooling capacity of the mold is weak, the cooling of the whole billet in the mold will be slow, which will affect the solidification of the billet. When the billet reaches the outlet, if a sufficiently thick billet shell is not formed, the steel leakage accident is likely to occur.

Cooling water temperature --- even though the cooling water flow velocity in the water slot of the crystallizer is very high, the water film velocity along the outer wall of the copper pipe sleeve is low due to the boundary effect in the flow process. When the flow rate is low, the boiling point supersaturation temperature of the cooling water can reach 120 ℃, and the supersaturation boiling point of the water film along the copper pipe wall can reach 150 ℃.

Cooling water quality --- if the cooling water quality is not softened, the ca *, MG1, Fe * * Zn "plasma is easy to deposit and form scale, which affects the heat transfer efficiency of the copper pipe. Even if the thickness of the precipitated material is only 20um, it will increase the temperature of the cold and hot surfaces and cause uneven heat transfer, and even lead to excessive accumulation of heat locally and permanent deformation of the copper pipe, and serious local boiling will cause permanent deformation of the water jacket of the crystallizer. Therefore, the cooling water of the crystallizer is required to be softened water.

Improve off square --- the mold with serious scale on the outer wall of the copper tube often produces defective billet, such as off square. When disassembling and inspecting the crystallizer with square deviation, it was found that the inner cavity wall of the upper mouth of the copper tube was bluish, the outer wall of the copper tube was very fine white spots, and the water jacket was bulged and deformed locally. It was found that the hardness of the cooling water of the crystallizer seriously exceeded the standard. After adjusting the water quality, the above phenomenon disappeared and the stripping was improved.