Makino H, Maeda Y, Nomura H

Abstract: Recently, the need to reduce the weight of automobiles has prompted the demand for near-net-shape iron castings. In order to produce a high quality mold to satisfy such demands, it is necessary to define a molding method, which will optimize the green sand molding process. Green sand molding processes using compressed air and squeeze have been increasingly used to replace jolt-squeeze molding. Green sand molding methods have been divided into two main types: air-flow/squeeze and blow/squeeze. To achieve the best results, it’s essential to know how sand particles react during the air-flow or blow stages. Furthermore, it is necessary to analyze each process using the same mathematical model since the squeeze is applied after the first stages of the air flow or blow methods. In this study, the authors have developed a mathematical model using the Distinct Element Method (DEM), which is a discontinuous method. By this method it is possible to analyze the various molding processes. The squeeze molding method is analyzed by taking particle size distribution into consideration. The laboratory experiments are carried out to test the validity of the present mathematical model. By both experimentation and simulation, the effect of particle size distribution on sand compacting behavior is clarified. Furthermore, the present model is applied to segmented squeeze molding. This study has provided new and valuable information on the behavior of sand particles during sand molding processes.

Keywords: Computer simulation, Distinct element method, Squeeze molding.