2013 年 85 巻 2 号 p. 107-112
Frozen mold casting provides industrial advantages such as improvement of working conditions and reduction of factory waste. However, to put it to practical application, it is important to establish economical and productive freezing technique for casting sand molds. The differential pressure freezing method which enables sand molds to be frozen in the short time at lower costs is drawing attention as a useful way to produce frozen molds, but there still remain some problems with regard to mold surface conditions. In this study, the authors reviewed a new differential pressure freezing method which is suitable for the core molds, whose entire surface is usually covered by molten metal in the casting. A hollow core was prepared and pressure difference was given between the hollow portion and outer space to cause aeration in the radius direction. It was confirmed that frozen core molds produced by this process had uniform lateral surfaces with good conditions. Moreover, the hollow frozen core molds did not break during casting work, and successfully provided the desired cavity in castings. We also developed an air-through mold form material to facilitate the above freezing method. This air-through material has eased most of the regulations on core geometry in the freezing method, enabling production of frozen mold with irregular and/or curved surfaces easily.