INJECTION MOLDING METHOD

摘要

An apparatus for molding an optical lens from a molten thermoplastic resin material using an injection molding machine, and including means for forming a mold cavity defined by a pair of opposed, spaced apart inserts shaped and configured to define opposite faces of said optical lens and having a plurality of overflow wells surrounding the mold cavity means for injecting a predetermined optimum volume of resin material into said mold cavity; means for controllably moving at least one insert relative to the other insert, wherein such relative insert motion is driven by a power cylinder capable of providing a variable compression stroke during molding and is initiated prior to completion of said injection; means for controlling the velocity and/or compressive force of the compression stroke of said power cylinder such that said compression is conducted at a first selected relatively high velocity, thus urging excess resin from said cavity into said overflow wells after which the compression force is varied to a secondary selected level; means for maintaining the secondary selected compressive force on said mold cavity; and means for ejecting the lens.