| 摘要 |
PURPOSE:To improve the accuracy and the life of a mold by bringing a silicon nitride ceramic tubular body to shrinkage fit into a metallic cylindrical body, and also setting the thickness of each layer to a specified thickness or above. CONSTITUTION:A ceramic tubular body 2 consisting of silicon nitride ceramics forms a mold space 3. Both a metallic cylindrical body 4 and the tubular body 2 are set to thickness of >=5mm so as to stand a high pressure at the time of die casting. The metallic cylindrical body 4 of an SKD material, etc. is heated to about 700-800 deg.C, and thereafter, the ceramic tubular body 2 is pressed in and a shrinkage fit is executed. In this mold 1, the wall surface for contacting a molten metal is formed by polished silicon nitride ceramics, therefore, its accuracy is high, its coefficient of thermal expansion is low, and also the corrosion resistance against an Al molten metal, etc. is improved. Accordingly, both the accuracy and the life of the mold are improved. |
