Nissei Plastic Industrial Co., Ltd.

Akira Iijima

Kazuki Miyairi

An improved injection mold for molding an information recording disc is provided. It includes a holder frame fitted to a mold fitting plate, a mirror platen member for a stamper held in the holder frame, a tubular inner periphery holder fitted into a central hole bored through the mirror platen member and provided with a threaded portion on the outer periphery thereof near the leading end, a pilot bush and an anchor nut for holding the inner periphery holder, and is characterized in that said inner periphery holder is provided with a screw section having a plurality of intermittently disposed threaded portions projecting forwardly from the leading end thereof and said pilot bush is provided at the leading end thereof with a locking flange having at areas close to the center thereof through holes for allowing respective threaded portions to run therethrough and project further while the mold fitting plate is provided in the inside with an rotatable anchor nut so that the inner periphery holder can be firmly secured to the mold fitting plate through screwed engagement of the anchor nut and the threaded section can be made to abut the corresponding surface of the locking flange.

Injection mold for molding information recording discs

A method for positioning both dies set to both movable and stationary platens of a plastic molding machine to form a cavity by fitting convex and concave portions formed on the facing surfaces of the dies into a spigot respectively, wherein a movable die is set to the movable platen at the retreat position to secure the movable die to the home position and a stationary die is temporarily clamped at the home position of the stationary platen by pressing the stationary die in the lateral direction by a repulsive member, the movable die is advanced against the stationary die under the above state, die matching of the stationary and movable dies is performed by fitting the convex portion to the concave portion, and thereby positioning of the stationary die is performed by correcting the position of the die before permanently clamping the stationary die to the stationary platen under the state in which the both dies are fastened by the movable platen. Thereby, positioning of high-accuracy dies with a small clearance of the fitting portion can be easily performed.

Growing community of inventors

Sakaki-machi, Japan

Akira Iijima