| 摘要 |
PROBLEM TO BE SOLVED: To control enlarging of the inner circumference when a protective film is formed so that the protective film can be advantageously and stably formed, by covering the inner circumferential surface of the center hole of a stamper with a perpendicular effecting surface when the stamper is set. SOLUTION: A movable side insert sleeve 48 has a perpendicular effecting face 62 for a step which is circular and almost perpendicular to a cavity forming face 52 of a movable side. The outside circumferential face of the face 62 constitutes a part of the face 52 cooperating with the surface of a mirror block 46 to form a mounting face 64 for a stamper, and an annular projection 78 is formed on the inside circumferential part of the face 62. Thereby, when an optical disk substrate is produced, an annular thin plate stamper 68 is superposed on the surface 64 of a movable die 32 and alined by fitting the center hole of the stamper 68 to the face 62. While a fixing die and the molding die 32 are clamped, a resin material is supplied through a sprue bushing and a runner part to be packed in the forming cavity so that a substrate with information transferred on the stamper 68 is formed. |
