In-Mold Lens Coating Containment via Edge Grooving
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Solution Overview
Problem
In-mold coating of lenses faces issues with coating solution leakage, which affects coverage and thickness, and existing solutions are not suitable for edge-gated injection molds used in ophthalmic lens manufacturing, leading to contamination and damage to the mold.
Innovation Solution
A method and apparatus that form a containment lip by chamfering or V-grooving the peripheral edge of the concave optical insert and receiver rings, creating a channel with an open cross-sectional geometry to prevent coating leakage and ensure uniform coating application across the lens surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thin coating containment flange is provided around the perimeter of the molded article, then coating leakage is prevented, but the solution is not suitable for edge-gated injection molds used in ophthalmic lens manufacturing
Solution Approach 1:
The patent applies a localized chamfer or V-groove at the peripheral edge of the optical insert where the coating containment is needed, rather than providing a complete flange around the entire perimeter. This localized modification provides the necessary coating containment while maintaining compatibility with edge-gated injection molds and allowing frequent insert changes.
Solution Approach 2:
The containment structure is segmented into discrete features (chamfer or V-groove) at specific locations rather than a continuous flange. This segmentation allows the solution to work with edge-gated molds where inserts need to be frequently changed, as the containment features are integrated into the insert design itself rather than requiring a separate mold modification.
2Manufacturing precision
If coating solution is applied to the lens surface, then uniform coating is achieved, but coating solution leaks out of the mold cavity affecting coverage and thickness
Solution Approach 1:
The chamfer or V-groove containment features are pre-formed on the optical insert before coating application. This preliminary structural preparation creates the necessary containment barriers that prevent coating solution leakage during the subsequent coating process, ensuring both uniformity and preventing substance loss.
3Reliability
If the flange is made thinner to reduce shrinkage, then resistance to coating flow is minimized, but coating leakage is reduced
Solution Approach 1:
Instead of modifying the entire flange structure, the patent applies localized chamfer or V-groove features at the peripheral edge. This approach provides effective coating containment without requiring complex overall insert design changes, maintaining simplicity while achieving the containment function.
Data Source
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AI summary
A method and apparatus for coating lenses within an injection molding machine having a concave optical insert with a perimeter edge that meets the receiver ring in an annular contact region. A channel is formed throughout the annular contact region. When molding a lens with the apparatus, and according to the method, a closed-loop coating containment lip is formed by the channel. After the lens has solidified and the mold is opened, a predetermined volume of coating solution is applied and the mold is re-clamped. A uniformly thin layer of coating is cured on to the convex lens surface by avoiding coating run off and preventing mold contamination.