| 摘要 |
PURPOSE:To obtain the mold for molding synthetic resin excellent in performance, while eliminating the casting defect such as pin holes, etc., and obtaining fine structure and high mirror surface property by casting the molding portion of the mold, using a specified CV cast iron. CONSTITUTION:A mold comprises molding portion 1 whose thickness is in the range of 20mm-200mm, and its structure is CV graphite type. The mold portion 1 is cast with CV cast iron in which 80% or more of graphite particle diameter is equal to or less than 0.2mm. Recessed grooves 2 are formed on the outer wall of the molding portion 1, and into these grooves 2, cooling pipes 3 are fitted and fastened. In the case of large mold 1, the molding portion of the mold is surrounded by a frame body for back up. The wall thickness of the molding portion is set at 20mm-200mm. Consequently the graphite particle diameter contained in the inner structure of the molding portion 1 and in the structure of the molding surface, becomes fine due to increase of their solidification speeds, whereby the occurrence of pin holes and gas defects may be suppressed. As the result of the occurrence of structure-fineness, the mold strength is improved, and the breakage of the edge part of the molding portion may be prevented, thereby improving the mold life.
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