A study of freeze mold method by cold air to reduce environmental load

本研究报道了用“冷冻模法”进行砂型成型的冻结特性。冻模法是一种浇铸工艺，在铸砂中加入少量的水，然后将其冷冻并硬化为模具。代替使用有机硬化剂，这种成型技术可能减少资源和环境负荷。E针对冻模法的实际应用，选择冷气流作为带走模具热量的介质。首先，将带水的沙子填入一个矩形容器中，这就是测试截面。然后冷空气流入容器。因此，模具被冷气流冷却和冻结。实验研究了在添加水量、表面流速、入风温度和固定床层高度等条件下，冷气流对样品的冻结行为。结果表明，随着添加水量的增加，冻结完成时间变长。而添加水量的增加对试验段压力损失影响不大。并推导了预测冻结完井时间的经验方程。另一方面，研究了将低熔点金属液注入冷冻铸砂时，铸砂内的传热传质特性。此外，还对冷气流对铸砂中水的冻结行为进行了数值分析。数值分析结果与实验结果吻合较好。

This research reports the freezing characteristics of sand molded with "the freeze mold method". The freeze mold method is the casting process where little water is added to cast sand then they are frozen and become harden as a mold. Instead of using organic hardener, this molding technology possibly reduces resources and environment loading.e aimed at the practical application of the freeze mold method and chose cold airflow as the medium taking heat away from the mold. At first the sand with water was filled into a rectangular container that is the test section. Then cold air flowed into the container. Consequently, the mold was cooled and frozen by the cold airflow.The freezing behavior of the sample by cold airflow was investigated experimentally under the conditions of added water amount, superficial velocity, inflow air temperature and fixed bed height As a result, the freezing completion time becomes long as the added water amount increases. However, an increase in the added water amount doesn't influence the pressure loss of the test section so much. Moreover, the empirical equation was derived to predict the freezing completion time.On the other hand, the heat and mass transfer characteristics in the cast sand were investigated, when the molten metal, which has the low-melting point, was fed into the frozen cast sand,.Additionally, numerical analysis of the freezing behavior about the water in the cast sand by cold airflow was carried out. The results of the numerical analysis give close agreement with the experimental results.