| 摘要 |
PROBLEM TO BE SOLVED: To provide a three-layered molten metal injection molding sleeve having an excellent heat retaining property wherein an external cylinder and an intermediate member, and the intermediate member and an internal cylinder are correctly bound and the entire sleeve is not loosened even if the external cylinder reaches a relatively high temperature when the sleeve is used for practical injection-molding of the molten metal. SOLUTION: The sleeve so constituted that the internal cylinder comprising silicon nitride ceramics, the external cylinder comprising a heat resistant metal and the intermediate member comprising a thermal insulating material between the internal cylinder and the external cylinder are provided is characterized in that the expansion coefficient of the intermediate member at a room temperature is bigger than those of the internal cylinder and the external cylinder. COPYRIGHT: (C)2003,JPO
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