| 摘要 |
PROBLEM TO BE SOLVED: To make sufficiently securable a storage area even in a small-sized magnetic disk by fitting a punch arranging an ejector pin on its center to a central part of a movable side die, retreating the ejector pin than the punch to oppose to a sprue part and forming a space of a specified value. SOLUTION: The space of a size 1-2 mm is formed as a cold slug part. The ejector pin 36, the punch 37 and an ejector sleeve 38 are arranged on the movable side die central part. The cold slug part 39 is provided on its central part, and is made a slender shape of the size 1-2 mm extent so as to be easily cooled to be formed so that the heat storage capacity is reduced to be solidified rapidly. Thus, the temp. distribution in the die is uniformized, and a substrate birefringence increase in on the inner peripheral side is suppressed, and a complex double structure containing a cooling circuit of the punch and a punch sleeve is not necessitated, and it is suited to small-sized disk molding incorporating mechanical strength also.
|
