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US 7,459,120 B2Granted
Low pressure thermoforming of thin, optical carriers
AssigneeEssilor International
InventorsTimothy E. Herod, Hsinjin E. Yang
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Abstract
A method for thermoforming a thin thermoplastic carrier with uniformity of thickness at optical quality. The sheet to be thermoformed is heated and placed on a vented platform equipped with a mold insert. The thermoformer's platens clamp a shroud over the sheet. A low pressure air stream is introduced into the shroud and deflected from a direct path leading to the mold insert.
Claims30
A method for thermoforming a thin thermoplastic carrier with uniformity of thickness at optical quality comprising the steps of:
- locating a heated sheet on a vented platform equipped with a mold insert that is adjustably disposed though an aperture and clamping the thermoformer's platens to clamp a shroud having a geometry matched to the mold insert's periphery over the heated sheet onto the vented platform;
- confining a low pressure air stream within the shroud with the vents being located between the aperture and the shroud;
- and
- deflecting the air stream from a path leading directly to the mold insert thereby thermoforming the sheet to produce a uniformly thick optical carrier at optical quality.
1 more element
Dependencies are inferred from the claim text.