Plastic and nonmetallic article shaping or treating: processes – Optical article shaping or treating – Changing mold size or shape during molding or with shrinkage...
Patent
1987-10-05
1989-06-06
Lowe, James
Plastic and nonmetallic article shaping or treating: processes
Optical article shaping or treating
Changing mold size or shape during molding or with shrinkage...
2642973, 2642978, 2643287, 2643288, 26432816, 425547, 425552, 425555, 425808, 425DIG201, B29D 1100
Patent
active
048369608
ABSTRACT:
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.
REFERENCES:
patent: 2424235 (1947-07-01), Hoffer
patent: 4091057 (1978-05-01), Weber
patent: 4254065 (1981-03-01), Ratkowski
patent: 4364878 (1982-12-01), Laliberte et al.
patent: 4540534 (1985-09-01), Gendol
patent: 4569807 (1986-02-01), Boudet
patent: 4664854 (1987-05-01), Bakalar
Producing Precision Parts at Injection Speeds, J. Greener, Plastics Engineering, Jun. 87.
Kingsbury Jeffrey M.
Spector David P.
Cohen Howard
Lowe James
Sola USA, Inc.
Zimmerman Harris
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