초록 ▼

A method and apparatus for the fabrication of optical lenses by injection/compression molding of thermoplastic includes a plurality of sleeves, each having a bore therethrough, and a plurality of mold inserts dimensioned to be received in the bore with minimal clearance for sliding fit. The mold ins

A method and apparatus for the fabrication of optical lenses by injection/compression molding of thermoplastic includes a plurality of sleeves, each having a bore therethrough, and a plurality of mold inserts dimensioned to be received in the bore with minimal clearance for sliding fit. The mold inserts each include a precision optical surface adapted to form a front or back surface of a lens. A selected pair of mold inserts are placed in the bore of a sleeve with front and back surface forming optical surfaces in confronting relationship to define a mold cavity, and the assembly is heated to a temperature above the glass transition temperature of the thermoplastic to be molded. An injection port extends through the sleeve to the bore, and is positioned to inject thermoplastic that has been heated to a fluid state into the cavity. After injection of the thermoplastic, the mold inserts are compressed together, and excess thermoplastic is forced out of the mold cavity. The mold inserts are then translated together relative to the sleeve to uncouple the injection port from the cavity. Compressive pressure is then maintained on the mold inserts while the mold assembly is cooled below the glass transition temperature. The mold inserts are pulled from the sleeve, and the finished lens is removed.

대표청구항 ▼

A method for molding a component in a molding cavity defined by a pair of axially spaced molds slidably mounted within a sleeve, which comprises the steps of spacing the molds to define a cavity having a volume in excess of that required to form the finished component, filling the cavity with a poly

A method for molding a component in a molding cavity defined by a pair of axially spaced molds slidably mounted within a sleeve, which comprises the steps of spacing the molds to define a cavity having a volume in excess of that required to form the finished component, filling the cavity with a polymeric molding material at a temperature of the same order as the molds defining the molding cavity by extrusion through an inlet passage in said sleeve, at least the molds having been heated to a temperature above, but relatively close to, the glass transition temperature of the molding material, moving one or both molds to reduce the volume of the cavity to the desired size of the component plus any allowance for thermal shrinkage thereby compressing the molding material within the cavity and causing any excess molding material to be extruded out of the mold cavity, applying pressure to the molten material through one or both of the molds to form the component under conditions where shrinkage is accommodated while gradually cooling the molds, the sleeve and the component through the glass transition temperature, and removing the molds and the component from the sleeve. An apparatus for molding finished ophthalmic lenses, comprising a plurality of molding assemblies, each molding assembly including a sleeve member having a bore extending therein, a pair of mold dies having contoured molding surfaces adapted to form complementary front and back surfaces of a lens, said dies further including outer peripheral surfaces dimensioned to be received in said bore with minimal clearance for sliding translation therein, said mold dies being received in said bore in spaced apart relationship to define therebetween a mold cavity; means for processing said plurality of molding assemblies individually and consecutively, including means for injecting a thermoplastic molding material in a molten state into said mold cavity, means for moving said mold dies together to compress said molding material and to squeeze excess molding material from said molding cavity.