| 摘要 |
A fixed split mold and a movable split mold are clamped with each other to define a cavity for molding an optical disk. An annular tapered unit of the fixed mold includes a flange member and a tapered member threadably engaged with the flange member and having a tapered outer peripheral surface. The movable mold includes a base member and a tapered flange member having a tapered inner peripheral surface having an inclination equivalent to that of the tapered outer peripheral surface. After the fixed mold and movable mold are clamped to align the first and second molds, the mold assembly is mounted on and secured to a molding machine. Then, the bolts and nuts are removed and the tapered member is detached. Subsequent successive closing and opening operations of the mold assembly for molding operations do not cause any unevenness of the depth of the cavity, thereby obtaining a uniform thickness in the products which are also free from birefringence.
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