Conformal Cooling Inserts for Lens Molding Thermal Uniformity

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Solution Overview

Problem

Conventional lens manufacturing systems face issues with uneven cooling in injection molding, leading to defects such as weld-lines, warping, and birefringence due to non-uniform heat transfer across mold cavities, which increases production costs and decreases efficiency.

Innovation Solution

The implementation of conformal heat transfer inserts with sealed fluid inlets, outlets, and conduits that are shaped to match the geometry of the lens cavities, allowing for uniform cooling and enhanced heat transfer through the use of additive manufacturing technologies to create complex conduit geometries that facilitate efficient heat dissipation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional cooling channels are used in injection molding, then the manufacturing process is simple, but uneven cooling occurs leading to defects such as weld-lines, warping, and birefringence

Engineering Contradiction:
Improvecooling uniformityVSAvoidcooling channel geometry
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The cooling channels are designed with conformal geometry that matches the local thickness and shape of the mold cavity. This allows different regions of the mold to receive appropriate cooling rates tailored to their specific thermal requirements, ensuring uniform cooling across the entire part while maintaining manufacturing precision.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The cooling channels transition from conventional straight or curved paths to three-dimensional conformal pathways that follow the contour of the mold cavity. This dimensional complexity enables the cooling fluid to access all regions of the cavity uniformly, eliminating hot spots and thermal gradients that cause defects.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Productivity

If conventional cooling channels are used, then device complexity is low, but manufacturing cycle time increases due to non-uniform heat transfer

Engineering Contradiction:
Improvemanufacturing cycle timeVSAvoidcooling channel geometry
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The conformal cooling channels are positioned at optimal distances from the cavity surface in different regions, allowing thick sections to receive more cooling and thin sections to receive less, thereby achieving uniform cooling rates across the entire part and reducing overall cycle time.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

By implementing three-dimensional conformal cooling pathways that follow the mold cavity geometry, the system achieves superior heat transfer efficiency compared to conventional two-dimensional cooling plates, significantly reducing manufacturing cycle time.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

3Manufacturing precision

If conformal heat transfer inserts are implemented, then cooling uniformity and quality improve, but manufacturing complexity and initial cost increase

Engineering Contradiction:
Improvepart qualityVSAvoidinsert fabrication
Core Design Contradiction:
Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The conformal cooling channels are designed and fabricated as integral parts of the mold or as pre-assembled heat transfer inserts before the actual production process begins. This preliminary fabrication, though complex, eliminates the need for complex assembly during mold setup and ensures consistent cooling performance throughout production.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

Heat transfer inserts serve as intermediary components that can be separately fabricated using advanced manufacturing techniques and then integrated into the mold. This approach allows for optimized cooling channel design while maintaining ease of mold assembly and replacement.

Inventive Principle:
Principle #24Intermediary (Mediator)

4Loss of time

If conformal cooling channels are used, then manufacturing cycle time decreases, but device complexity increases

Engineering Contradiction:
Improvecooling timeVSAvoidcooling system structure
Core Design Contradiction:
Loss of timeVSDevice complexity

Solution Approach 1:

The conformal cooling channels provide locally optimized cooling rates throughout the mold cavity, ensuring that all regions cool at the appropriate pace simultaneously. This eliminates the need for extended cooling times required by conventional systems that must accommodate the slowest-cooling region.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The conformal cooling channels maintain continuous and uniform heat extraction throughout the entire cooling process, eliminating thermal gradients and hot spots that would otherwise require extended cooling time. This continuous effective cooling action significantly reduces the loss of time in manufacturing.

Inventive Principle:
Principle #20Continuity of useful action

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 ensures uniform cooling across all cavities, reducing the risk of defects and significantly decreasing manufacturing cycle times, thereby improving the quality and efficiency of lens production.

Implementation Method 1

a conformal fluid conduit extending from the sealed fluid inlet to the sealed fluid outlet... enhanced heat transfer through the use of additive manufacturing technologies

Methodology Applied
Scientific EffectHeat transfer: Conduction (thermal)

Implementation Method 2

circulating a cooled fluid through the conformal cooling channels... facilitates efficient heat dissipation

Methodology Applied
Scientific EffectConvection: Convection

Implementation Method 3

uniform cooling across all cavities... efficient heat dissipation

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentEP3433645B1System and method for conformal cooling during a lens manufacturing process
Publication Date: 2023.12.20 ESSILOR INTERNATIONAL(COMPAGNIE GENERALE D OPTIQUE)
  • EP3433645B1 patent drawingFigure 1
  • EP3433645B1 patent drawingFigure 2
  • EP3433645B1 patent drawingFigure 3A~3B

AI summary

The disclosed embodiments include a system and method for manufacturing a lens. In one embodiment, the system includes a lens mold. According to the embodiment, the lens mold contains a part cavity and a material flow path fluidly coupled to the part cavity and a lens material inlet. The system also includes a heat transfer insert. According to the embodiment, the heat transfer insert includes an insert surface positioned adjacent to a part surface of the cavity, a sealed fluid inlet, a sealed fluid outlet, and a conformal fluid conduit that extends from the sealed fluid inlet to the sealed fluid outlet.