빌렛 주형 설계에 대한 엔지니어링 연구

Abstract

Billet mold is a casting device which turns liquid steel to solid one. In the past, production is only an important factor in the steelmaking industry. However, quality also becomes very crucial due to diversification of demand. Since high production needs high casting speed and it cause various surface cracks, High production with high quality of billet product was a contradiction. To overcome the problem, surface crack should be prevented by minimizing air gaps, which are the main cause of uneven solidifying shell, between shell and mold by controlling mold distortion in the side of mold device itself. Also, cooling water of mold should be under conditions of reducing boiling, which makes water scale deposit interrupting heat transfer. This paper mentions how to minimize mold distortion and control boiling conditions of cooling water. To do the former, heat transfer analysis by ANSYS was firstly performed to achieve a right taper size, and after that, Thermal mechanical analysis was done to get optimal conditions of minimizing mold distortion with various cases such as tapers, support positions, wall thicknesses, and cooling water velocities. It becomes clear that wall thicknesses and cooling water velocities were the most important factors to be related with mold distortion. And this study suggested proper conditions of mold design concepts. In addition, operating conditions of cooling water were calculated to prevent boiling of cooling water. Boiling curve was used to set boiling phases, and heat flux of each phase is calculated. Surface temperature of mold and partial boiling temperature of cooling water were calculated and compared to figure out boiling status, and suggested non-boiling conditions.