Metal Tray and Plastic Mold Support for Uniform Lens Curing
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Solution Overview
Problem
The production of contact lenses using inexpensive single-use mold halves faces challenges with material deformation during curing and the need for uniform heating to prevent non-uniform lens geometry and optical power, while existing reusable glass mold halves are expensive and unsuitable for thermal curing.
Innovation Solution
An apparatus comprising a metal tray with a plastic mold support and injection-moldable polyolefine lens molds, where the mold support is fixed to the tray with a resilient latch, allowing for precise alignment and uniform heating through convection, enabling high-volume simultaneous curing without deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If inexpensive injection-molded plastic mold halves are used, then cost is reduced and productivity is improved, but the mold halves deform during thermal curing causing poor manufacturing precision
Solution Approach 1:
A metal support plate is introduced as an intermediary between the heating source and the plastic mold halves. The metal plate has high thermal conductivity and acts as a heat distributor, ensuring uniform heat flow to the molds. This mediator prevents localized overheating that causes deformation, allowing inexpensive plastic molds to be used without sacrificing precision.
Solution Approach 2:
The invention changes the thermal parameters of the curing system by using a metal support plate with specific thermal conductivity properties. The plate distributes heat uniformly across the mold surfaces, controlling the temperature gradient during curing. This parameter control prevents excessive shrinkage and deformation of the lens-forming material, maintaining manufacturing precision even with disposable molds.
2Productivity
If rapid curing is applied to improve productivity, then production speed increases, but non-uniform heating causes deformation and poor lens quality
Solution Approach 1:
The metal support plate serves as a thermal intermediary that mediates between the rapid heating source and the mold halves. Its high thermal conductivity allows it to quickly distribute heat uniformly across all molds simultaneously, enabling rapid curing without creating hot spots that would cause deformation.
Solution Approach 2:
The metal support plate creates equipotential thermal conditions across all mold surfaces by conducting heat uniformly. This ensures that all lens-forming materials experience the same thermal conditions simultaneously, allowing rapid curing while maintaining geometric uniformity and preventing deformation.
3Manufacturing precision
If reusable glass mold halves are used, then manufacturing precision is maintained, but cost increases and thermal curing suitability is reduced
Solution Approach 1:
The invention enables the use of inexpensive disposable plastic mold halves by introducing a metal support plate that provides the necessary thermal control. The disposable molds, when used with the metal plate, achieve precision comparable to expensive reusable glass molds, making the cheap single-use option viable for thermal curing applications.
Solution Approach 2:
The metal support plate acts as a mediator that compensates for the thermal deficiencies of inexpensive plastic molds. It ensures uniform heat distribution that prevents deformation, allowing disposable molds to achieve the same precision outcomes as traditional reusable glass molds while reducing cost.
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
This setup ensures high-quality contact lenses with uniform curing, preventing material deformation and allowing for efficient production with inexpensive mold halves, while maintaining the quality and geometry of the lenses.
Implementation Method 1
a metal tray, for example aluminum
Implementation Method 2
exposing the mold (the mated mold halves) and the lens-forming material contained therein to heat of a predetermined temperature and over an extended period of time
Data Source
Figure 1~2
Figure 3~6
Figure 7~8
AI summary
An apparatus (1, 2) for the thermal curing of a lens-forming material contained in a lens mold (10, 60) to form an ophthalmic lens comprises: a tray (30, 40) made of metal, the tray having a fixation opening, a mold support (20, 50) made of plastic, wherein the mold support has a fastener (25, 53) fixed to the tray at the fixation opening (31, 41) and fixing the mold support to the tray, wherein the mold support further has a positioning guide (27, 55) configured to position a lens mold on the mold support in a predetermined position relative to the tray and wherein the mold support further has a support surface (23, 52), and a lens mold arranged on the mold support, the lens mold having a bearing surface (11, 61) resting on the support surface of the mold support. The lens mold is arranged spaced apart from the tray by a clearance distance (C, T)