Verfahren und Vorrichtung zur Laser-Entformung

• Main Authors: DAGOBERT, HENRI ARMAND, WALKER, CRAIG WILLIAM
• Format: Patent
• Language: German
• Published: 09.01.2003
• Edition: 7
• Subjects: AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING; CASTING; CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES; CONTACT LENSES; OPTICS; PERFORMING OPERATIONS; PHYSICS; POWDER METALLURGY; PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCESIN A PLASTIC STATE; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDEDFOR; SHAPING OR JOINING OF PLASTICS; SPECTACLES; SUNGLASSES OR GOGGLES INSOFAR AS THEY HAVE THE SAME FEATURESAS SPECTACLES; TRANSPORTING; WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE, IN GENERAL

An automated demolding apparatus for reliably and repeatedly mechanically separating contact lens mold portions of a mold assembly without damaging the contact lens formed therebetween. The mold assembly includes a first front mold portion having a central mold section with a surrounding flange, and a corresponding second back mold portion also having a central mold section with a surrounding flange. A molded contact lens is formed between the front and back mold portions, and the flanges of the front and back mold portions are spaced apart and parallel to each other. The demolding apparatus includes restraining fingers positioned between and on opposite sides of the spaced flanges of the first and second mold portions and against the flange of the first mold portion. A separating fixture includes separating fingers positioned between and on opposite sides of the spaced flanges of the first and second mold portions and against the flange of the second mold portion. Before demolding, the second mold portion is irradiated by a laser beam, which is absorbed thereby to cause a substantial temperature gradient between the second mold portion and the contact lens being demolded. The temperature gradient causes a differential expansion and shifting of the surface of the heated second mold portion relative to the surface of the lens to lessen the adhesion therebetween to assist in separation of the mold portions, while leaving the lens in the first mold portion. During demolding, the separating fixture is rotated relative to the restraining fingers to progressively separate and peel the second mold portion from the first mold portion.