Cast Mould Flexible Connection for Lens Manufacturing Precision
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Solution Overview
Problem
The existing cast moulds for manufacturing contact lenses or intraocular lenses face accuracy issues due to deformation of optically defined surfaces caused by material stress from positioning means, leading to inaccuracy and potential bubble formation during the manufacturing process.
Innovation Solution
A cast mould design with a rigid central part and a thin-walled, flexible connection between the bearing ring and central part, along with an injection mould using a plunger and spring means to compensate for plastic shrinkage, ensures that material stresses do not deform the optically defined surfaces and prevents bubble formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If positioning means are used to fasten cast mould halves, then ease of operation is improved, but manufacturing precision deteriorates due to deformation of optically defined surfaces
Solution Approach 1:
The cast mould half is divided into separate functional components: a bearing ring for positioning and a central part for optical surface formation. This segmentation allows the positioning function to be isolated from the optical surface, preventing deformation of the optically defined surfaces while maintaining ease of operation through the positioning means.
Solution Approach 2:
A flexible connection acts as an intermediary element between the bearing ring and the central part. This flexible connection absorbs and isolates the mechanical stresses from the positioning means, preventing them from being transmitted to the optically defined surfaces while still maintaining the structural integrity of the cast mould half.
2Strength
If rigid connection is used between bearing ring and central part, then strength is improved, but manufacturing precision deteriorates due to stress transmission
Solution Approach 1:
A flexible connection, resembling a thin-walled structure, is used to connect the bearing ring to the central part. This flexible connection provides sufficient structural strength to maintain the integrity of the cast mould half while simultaneously acting as a stress isolator that prevents mechanical stresses from reaching the optically defined surfaces, thereby preserving manufacturing precision.
3Productivity
If injection moulding is used to manufacture cast mould, then productivity is improved, but manufacturing precision deteriorates due to bubble formation and shrinkage
Solution Approach 1:
The flexible connection is specifically designed with appropriate wall thickness and structural characteristics before the injection moulding process. This preliminary design ensures that during injection moulding, the flexible connection can properly isolate stresses and prevent bubble formation in the optical areas, maintaining manufacturing precision while enabling efficient mass production through injection moulding.
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 maintains the accuracy of the optically defined surfaces, preventing deformation and bubble formation, resulting in high-quality contact lenses or intraocular lenses with improved optical quality and minimized contamination risk.
Implementation Method 1
a thin-walled, flexible connection which extends between the bearing ring and the central part and which connects the central part with the bearing ring
Implementation Method 2
The injection mould is provided with a plunger which is set up in the first injection mould half so as to be movable along a central axis of the plunger
Implementation Method 3
spring means which are set up in the first injection mould half and which are under a bias such that the spring action thereof urges the plunger in the direction of the central part cavity towards a pressed-in condition
Implementation Method 4
a monomer material is introduced into one of the two cast mould halves and then the second cast mould half is placed on the first cast mould half. Subsequently, the monomer material will polymerize
Data Source
AI summary
A cast mould for manufacturing a contact lens or an intraocular lens, wherein the cast mould is provided with a central part and a bearing ring and a flexible connection between the central part and the bearing ring. Further, an injection mould is provided for manufacturing such a cast mould and a method for manufacturing such a cast mould. The injection mould is provided with a mould cavity with a plunger biased by spring means towards the mould cavity which serves for compensating shrinkage which occurs during the curing of the plastic injected into the injection mould. Also described is a method for manufacturing a contact lens or intraocular lens with the aid of the cast mould, as well as a contact lens or intraocular lens obtained with this method.