| 摘要 |
PURPOSE:To obtain a frozen shell mold of the desired thickness and strength quickly by cooling a metal pattern in which the mulled sand for moisture contg. molds is packed, beforehand down to the freezing point or below. CONSTITUTION:A metal pattern plate 1 is placed on a cooler 2 which is held beforehand to the freezing point or below with the liquid nitrogen, the liquid carbon dioxide or the refrigerant liquid, and the mold ejection pins 3 are provided to a pattern plate base 1'. When the mulled sand 4 for the molds contg. 2-5% moisture is dropped on the plate 1 and is packed in the mold, a frozen layer 5 is formed along the surface of the plate 1 because the plate is cooled beforehand to the freezing point or below. The thickness of the layer 5 is a function of time, and when it increases to the prescribed thickness, the unfrozen excess sand 4 is removed and further the sand is allowed to freeze to the prescribed hardness, after which the pins 3 are operated to strip the layer 5, whereby the desired shell mold is constituted. |
