알루미늄 캐스팅 몰드용 주조재의 냉각 및 응력분포 특성에 관한 연구

Abstract

This study was experimentally and numerically investigated on cooling characteristics and stress distribution of AC7A and AC4C aluminum alloy casting material for manufacturing the automobile tire mold. the AC7A and AC4C casting material which used one of the aluminum alloy was selected as a casting material and the metal casting device was used in order to manufacture the mold product of automobile tire in the actual industrial field. The temperature distribution and the cooling time of these materials was experimentally measured and the result from the experiment was compared each other for the investigation of their cooling characteristics. Also, The displacement and the stress distribution of the used materials was numerically calculated. And then, the results of the experiment and numerical analysis were compared each other. The experimental set up for measuring temperature distribution and cooling time consisted of the casting, the metal mold device, data acqusition unit, 9 K-type thermocouples and PC. Also, for the numerical analysis, "COMSOL Multiphysics 3.3 Ver", the commercial program based on the partial differential equation (PDE), was used in order to predict the displacement and stress distribution inside the tire mold during the cooling process. The experimental result revealed that the cooling time of AC7A casting material was faster than cooling time of AC4C casting material about 20 minutes. And, AC7A casting material was faster than AC4C casting material about 10 minutes, when the casting was separated from permanent mold device. Also, the numerical result occurred that the displacement and stress distribution of AC7A casting material was higher than AC4C casting material about 1.7mm and 0.1GPa, respectively. In addition, the results of displacement and stress distributions appeared to be larger at the center parts of tread part in mold than on its sides because of the shrinkage caused by the cooling speed difference. Moreover, when the profiles of the temperature distribution were experimentally measured and were compared with those of the numerical result, it appeared that there was a slight temperature difference because of the latent heat by phase change heat transfer. However, the result of cooling temperature and patterns were almost similar except for the latent heat interval.