Before molten aluminum casting, the gap between the rolls, especially the gap when the two rolls are closest to each other, can be constant. Therefore, even if the caster nozzle is arranged before aluminum casting, the gap between the movable mold and the caster tip and nozzle becomes as small as possible, the gap sometimes widens during casting due to the opening of the gap between the rolls. More specifically, in some cases, the gap becomes 0.8 mm or more, thereby causing leakage of molten aluminum.
In consideration of the above situation, especially in the case of using a movable mold including a pair of rollers in the past, an attempt is made to prevent the molten liquid from leaking out through the gap between the movable mold and the caster tip. The circumference of the casting nozzle is controlled by increasing the casting speed to a given speed, or by adjusting the flow rate of the molten alloy liquid.
The aluminum water flowing from the tip of the nozzle first contacts the movable mold may become larger. However, longitudinal cracks are prone to occur due to increased casting speed, or the size of corrugated traces tends to become larger due to increased meniscus, which leads to a decrease in surface quality.
On the other hand, even if the aluminum casting nozzle tip is arranged so that the tip of the nozzle is in contact, at least the nozzle tip has excellent strength at the time of casting, and the nozzle is not easily worn out.
The nozzle head serves as a casting point can be arranged in a manner: the nozzle head is pressed on the movable mold before casting, and the material has excellent elastic deformability. In addition, even if the movable mold moves to expand the gap between the rollers, the nozzle can follow this movement, thereby maintaining the state before casting for a long time.
Therefore, the caster nozzle for aluminum casting having high strength and excellent elastic deformability can be arranged before casting, in such a way that the gap between the movable mold and the tip of the outer peripheral edge of the nozzle is minimized as much as possible. The tip may be arranged to contact the movable mold. That is, the gap between the tip of the outer peripheral edge of the nozzle and the movable mold can be substantially eliminated.
So, it is possible to obtain a cast alloy with excellent surface quality by suppressing the occurrence of longitudinal cracks and the expansion of corrugation marks, thereby reducing the deterioration of the surface quality.