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US 11,938,694 B2Granted
High speed injection molding with heat/cool cycle for making optical articles
AssigneeEssilor International
InventorsHao-Wen Chiu, Shannon Loiselle
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Abstract
A method for producing an optical article having a Fresnel microstructure and an injection molding system for producing such an article. The method includes heating and cooling a mold and applying a pressure to a thermoplastic material during injection molding of the optical article to facilitate formation of the Fresnel microstructure.
Claims13
A method for producing an optical article, the method comprising:
- (a) setting a surface temperature of a mold cavity to a cooling temperature at least 5° F. to 150° F. lower than a softening temperature of a thermoplastic material;
- (b) injecting the mold cavity with the thermoplastic material, the mold cavity including a Fresnel surface;
- (c) applying a compacting pressure to the thermoplastic material;
- (d) raising the surface temperature of the mold cavity to a heating temperature at least 20° F. higher than the cooling temperature;
- and
- (e) lowering a temperature of the mold cavity to the cooling temperature to form an optical article;
- wherein the thermoplastic material is a thermoplastic polyurethane (TPU), polyvinylchloride (PVC), or thermoplastic elastomer (TPE).
4 more elements
An injection molding system for producing an injection molded optical article, the injection molding system comprising:
- a mold having a mold cavity for receiving a thermoplastic material, the mold cavity including a Fresnel surface;
- a heat source in thermal communication with the mold;
- and
- a processor configured to successively perform:
- (i) controlling the heat source to set a surface temperature of the mold cavity to a cooling temperature at least 5° F. to 150° F. lower than a softening temperature of the thermoplastic material before an injection of said thermoplastic material in the mold cavity;
- (ii) after the injection of said thermoplastic material in the mold cavity, controlling the heat source to raise the surface temperature of the mold cavity to a heating temperature at least 20° F. higher than the cooling temperature;
- and
- (iii) controlling the heat source to lower a temperature of the mold cavity to the cooling temperature;
- wherein the thermoplastic material is a thermoplastic polyurethane (TPU), polyvinylchloride (PVC), or thermoplastic elastomer (TPE).
6 more elements
Dependencies are inferred from the claim text.