CRACKING PREVENTION DEVICE FOR ALUMINUM ALLOY INGOT, AND DC CASTING METHOD

PROBLEM TO BE SOLVED: To increase a contact area with an ingot, and reduce abrasion at a contact portion with the ingot for carrying out the coolant removal, resulting in the reduction of crack occurring rate of the ingot where the crack is easy to occur by installing a rotor for removing the coolant while an outer peripheral face contacts with the ingot. SOLUTION: When an ingot 4 is cooled by a mold 1, a solidification shell occurs on the surface. Then, when the ingot 4 reaches the bottom of the mold 1, a cooling water 6 is directly touched to the solidification shell from an inside 7 of the mold 1. Thereby, solidification inside the ingot 4 is rapidly proceeded. The cooling water 6 does not reach the ingot portion below the rotor by installing a rotor 2 for removing the cooling water at an appropriate position of the ingot 4, so as to significantly relief cooling. As a result, an internal stress is weakened and does not generate cracking, and the generated internal stress is softened by a self-annealing action. In the rotor 2, at least the portion contacting with the ingot 4 is preferably composed of an elastic material for improving a contact property with the ingot 4.