알루미늄 캐스팅 타이어 몰드의 열변형 해석에 관한 연구

Abstract

In this study, the thermal deformation inside the aluminum casting tire mold was analyzed using the numerical analysis method and was investigated using the experimental method. The metal casting device used for manufacturing the tire mold products for automobiles in the actual industrial field was selected as an analysis model, and Al-Mg system alloy (AC7A) widely used for metal casting was selected as the mold material. For the numerical analysis, "COMSOL Multiphysics", the commercial code based on the finite element analysis (FEA), was used in order to predict the thermal deformation of the AC7A including temperature, displacement and stress distribution. Also, in order to verify the results calculated by the numerical analysis, the experiment for temperature measurement inside the tire mold was performed using the K-type thermocouple under the same condition of numerical analysis method. In the numerical results, the results of the cooling temperature, displacement and stress distribution inside the tire mold using the metal casting method was better than those of the sand casting method and was improved the cooling completed time. Also, the analysis results by the pre-heated temperature conditions of metal casting device revealed that thermal deformation characteristics inside the tire mold is the most suitable for manufacturing mold products when the pre-heated temperature of core and casting device is about 80℃ and 300℃, respectively. In detail, the displacement inside the AC7A tire mold was closely related to the temperature difference. The displacement for 15 minutes in the metal casting device appeared to be larger at the center parts of tire mold (tread part) than on its sides, and the one calculated for the time until it was completely cooled at atmosphere temperature after it was removed from the metal casting device appeared to be larger on the measurement points of 1, 4 and 7 near the atmosphere than on other points. Moreover, the stress inside the AC7A tire mold appeared to be larger at the center parts of tire mold (tread part) because of the shrinkage caused by the cooling speed difference for the initial 15 minutes, and larger on the measurement points 2, 5 and 8 when the mold was removed from the metal casting device because of slow cooling speed. From these numerical analysis conditions and results, when the temperature distribution calculated by the numerical analysis and the one actually measured by the experiment were compared with each other, it appeared that there was a slight temperature difference between them because of the latent heat of the AC7A during the phase change process but their cooling patterns were almost similar results.