Net-molded Optical Articles Edge Wave Reduction
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Solution Overview
Problem
Conventional injection molding processes result in optical distortion and dimensional inaccuracies at the peripheral edges of optical articles due to uneven crystallization and cooling rates, leading to waste and inefficiencies in producing lenses and optical discs.
Innovation Solution
An injection molding apparatus with thermal regulating elements that control the cooling rate of the mold cavity, ensuring the peripheral edge and central portion cool at comparable rates, preventing premature solidification and crystallization at the edge, thereby maintaining uniform thickness and reducing optical distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional injection molding is used, then manufacturing speed and cost efficiency are improved, but optical distortion and dimensional inaccuracies occur at peripheral edges
Solution Approach 1:
The patent applies differential cooling rates to different regions of the mold cavity - the peripheral regions are cooled more slowly than the central region. This local variation in cooling quality allows the peripheral edges to maintain their shape and optical accuracy while still enabling efficient overall production. The heating element specifically targets the peripheral zones to prevent premature solidification and edge wave formation.
2Loss of time
If peripheral edges are cooled rapidly, then production time is reduced, but optical distortion and edge wave thickening occur
Solution Approach 1:
The patent implements dynamic temperature control during the cooling phase. A heating element is activated during the cooling process to dynamically adjust the temperature distribution within the mold cavity. This allows the peripheral edges to cool at a controlled, slower rate compared to the central region, preventing edge wave thickening while maintaining efficient production timing.
3Manufacturing precision
If lens blanks are cut to final shape, then optical distortion at edges is eliminated, but material waste increases and production time is extended
Solution Approach 1:
The patent performs the preliminary action of shaping the lens to its final dimensions directly during the injection molding process itself, rather than requiring subsequent cutting operations. By controlling the cooling rate differentially, the lens is formed with uniform thickness and optimal optical properties from the outset, eliminating the need for post-molding cutting and reducing material waste.
4Device complexity
If uniform cooling is applied throughout the mold cavity, then manufacturing simplicity is maintained, but edge solidification occurs before center, causing dimensional inaccuracies
Solution Approach 1:
The patent introduces localized heating elements in the peripheral regions of the mold cavity to create non-uniform cooling conditions. This local quality differentiation ensures that the peripheral edges do not solidify before the central region, preventing edge wave formation and dimensional inaccuracies while maintaining relatively simple overall cooling system architecture.
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 approach allows for the production of net-molded optical parts with reduced or eliminated edge distortion, increasing the usable surface area of optical discs and eliminating the need for cutting and finishing operations, thus enhancing the efficiency and quality of optical lenses and discs.
Implementation Method 1
a heating element disposed adjacent to the edge of the mold cavity...configured to supply heat to the peripheral edge
Implementation Method 2
a cooling element disposed in a second channel...configured to remove heat from the mold cavity
Implementation Method 3
During the chilling step, heat is removed from the plasticized material to convert it from a liquid consistency back to its original solid, rigid state. As the material cools, it also shrinks.
Data Source
AI summary
An injection molding apparatus and method of use are provided whereby a net-molded optical article can be produced. Edge wave deviations are reduced by controlling the cooling profile of the resin. The apparatus can be configured to include at least one heat control element disposed adjacent to an edge of the mold cavity. After plasticized resin has been injected into the mold cavity, the edge of the mold cavity can be thermally regulated relative to the center of the cavity.