Casting Cup Assembly for Ophthalmic Lens Manufacturing
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Solution Overview
Problem
Existing ophthalmic device manufacturing processes, such as contact lens production, face challenges in achieving precise and defect-free lens formation due to issues with mold separation and contamination during post-polymerization processing, leading to defects like holes, tears, and excess polymer rings.
Innovation Solution
A casting cup assembly with precision-manufactured frontcurve and basecurve molds featuring four blades on the periphery, which provide a larger footprint and planar offset for robust prying mechanisms, minimizing de-centering and tilting, and allowing for better control of monomer overflow, thereby reducing edge defects and improving lens formation accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional mold design is used, then manufacturing simplicity is maintained, but manufacturing precision deteriorates due to de-centering and tilting during mold separation
Solution Approach 1:
The mold is segmented into multiple functional components: frontcurve mold, basecurve mold, and four peripheral blades. This segmentation allows independent optimization of each component's function, with blades specifically designed to prevent de-centering and tilting during separation, thereby improving manufacturing precision without overwhelming complexity
Solution Approach 2:
The blades extend out of the plane of the mold surfaces, adding a dimensional element that provides mechanical leverage for precise alignment and separation. This out-of-plane structure creates a larger footprint for automated handling and provides robust prying points that minimize de-centering and tilting forces
2Productivity
If automated prying mechanisms are used, then productivity is improved, but manufacturing precision deteriorates due to contamination and defects during separation
Solution Approach 1:
The harmful function of blade contamination is extracted and redirected to a dedicated waste collection system. Excess monomer and flash material are channeled through the blade gaps into collection reservoirs, preventing contamination of the lens and allowing aggressive automated prying without compromising lens quality
Solution Approach 2:
The blades act as intermediary elements between the mold and the lens. They provide the mechanical interface for automated prying mechanisms while protecting the lens from direct contact with separation forces. The blades absorb and redirect forces that would otherwise cause tears or deformations in the lens edges
3Ease of operation
If robust prying mechanisms are used, then ease of operation is improved, but manufacturing precision deteriorates due to excess flash material interfering with separation
Solution Approach 1:
The excess monomer and flash material, which would normally be harmful contaminants, are converted into a beneficial flushing action. The robust prying forces that create these excess materials also drive them through the blade gaps into collection systems, transforming a source of defects into a self-cleaning mechanism that maintains lens edge quality
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enables more precise and repeatable separation of mold halves, reducing defects and improving the accuracy of lens formation by minimizing edge defects and contamination, resulting in higher yields of lenses that meet design specifications.
Implementation Method 1
a polymerization reaction within a casting cup assembly
Data Source
AI summary
Disclosed in this specification is a casting cup assembly comprising frontcurve and basecurve molds which of which includes a ring that circumscribes the respective concave and convex mold surface. When the casting cup is assembled, the rings align and minimize de-centering and tilting of the concave and convex mold surfaces which, in turn, reduces edge defects.