Casting Mold Tape for Straight Ophthalmic Lens Edges
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing ophthalmic lens manufacturing processes often result in lenses with irregularities such as wrinkled, twisted, or sticky peripheral edges, requiring further processing, and existing machines are not efficient, compact, or economical.
Innovation Solution
A machine and method using a mold assembly with a high Young's modulus adhesive tape member that forms a sealed molding cavity, allowing the first molding shell to displace relative to the second without deforming the adhesive tape, ensuring a straight peripheral edge by maintaining the adhesive tape's integrity during polymerization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional adhesive tape member is used to join molding shells, then the mold assembly can be assembled easily, but the adhesive tape deforms during polymerization causing wrinkled, twisted, or sticky peripheral edges on the lens
Solution Approach 1:
The patent applies parameter changes by specifying precise mechanical properties for the adhesive tape member: a Young's modulus between 100-500 MPa and a maximum shear stress between 0.01-0.05 MPa at polymerization temperature. These parameter specifications ensure the tape maintains structural integrity during polymerization while allowing sufficient flexibility for assembly, thereby preventing peripheral edge defects without requiring complex additional components.
2Productivity
If the molding shell is displaced relative to the other shell during polymerization, then the polymerization process can proceed, but the adhesive tape member deforms causing lens peripheral irregularities
Solution Approach 1:
The patent applies preliminary action by pre-configuring the adhesive tape member with specific mechanical properties (Young's modulus 100-500 MPa, maximum shear stress 0.01-0.05 MPa) before the polymerization process begins. This preliminary specification ensures the tape can withstand the displacement of molding shells during polymerization without deforming, thus maintaining peripheral edge quality while enabling efficient polymerization.
3Ease of manufacture
If the adhesive tape member has high flexibility for easy assembly, then the mold assembly is easy to construct, but the tape cannot maintain integrity during polymerization causing lens defects
Solution Approach 1:
The patent resolves this contradiction by optimizing the mechanical parameter range of the adhesive tape member. The Young's modulus of 100-500 MPa provides sufficient rigidity to maintain integrity during polymerization, while the maximum shear stress of 0.01-0.05 MPa ensures adequate flexibility for easy assembly. This parameter optimization achieves both ease of manufacture and reliability simultaneously.
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 method produces ophthalmic lenses with a straight, wrinkle-free peripheral edge, reducing the need for further processing and enhancing the manufacturing efficiency and economy of the process.
Implementation Method 1
said adhesive tape member having a Young's modulus greater than around 200 MPa, when measured at a temperature of polymerization of said polymerizable molding material, and a maximum shear stress smaller than around 0.05 MPa, when measured at said temperature of polymerization
Implementation Method 2
the molding material is preferably a polymerizable synthetic material, for instance UHI monomer or MR7 or MR8... the latter is polymerized thanks to a polymerization device, comprising for instance a lighting and heating source such as a UV source
Data Source
Figure 1~3B
Figure 4A~9
Figure 10
AI summary
The invention provides a machine for manufacturing an ophthalmic article (30) molded by casting and having a straight peripheral edge (33), comprising a mold assembly (2) having first and second molding shells (10, 13) provided with first and second predetermined molding surfaces (12, 14) and facing to each other, an adhesive tape member (20) joining said shells (10, 13) for forming a molding cavity (8), having a Young's modulus greater than 200 MPa and a maximum shear stress smaller than 0.05 MPa when measured at a temperature of polymerization of a molding material, and also configured to form a peripheral case of the mold assembly (2) in which said first molding shell (10) is able to be displaced relative to the second molding shell (13) without affecting an intermediate portion (22) of the adhesive tape member (20) which define said cavity (8), and a filling aperture (7) formed in said adhesive tape member (20) for introducing by casting said material into said cavity (8) for forming the article (30).