Laminated Glass Core-Clad Structure for Defect-Free Surfaces

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Solution Overview

Problem

The processing and handling of glass articles often result in surface defects due to mold imperfections, which are time-consuming and costly to remove through grinding or acid-etching, and can leave the surface roughened.

Innovation Solution

A laminated glass structure comprising a core and a clad, where the clad has a higher degradation rate than the core, allowing for the clad to be removed using a reagent without damaging the core, thus exposing a pristine surface.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If grinding and polishing are used to remove surface defects, then surface quality is improved, but production time and cost increase significantly

Engineering Contradiction:
Improvesurface qualityVSAvoidproduction time
Core Design Contradiction:
Manufacturing precisionVSLoss of time

Solution Approach 1:

The patent applies preliminary action by forming a sacrificial clad layer on the glass article surface before the molding process. This clad layer is designed to be removed easily after molding, having already protected the core glass during the molding process. The clad layer absorbs surface defects and damage during molding, eliminating the need for time-consuming grinding and polishing operations later.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent applies the extraction principle by removing the defective outer layer (clad) from the glass article after molding. The sacrificial clad layer, which contains the surface defects and molding imperfections, is selectively removed through chemical etching or mechanical means, revealing the pristine core glass surface underneath without requiring extensive polishing.

Inventive Principle:
Principle #2Taking out (Extraction)

2Manufacturing precision

If acid-etching is used to remove surface defects, then surface quality is improved, but the surface becomes visibly roughened

Engineering Contradiction:
Improvesurface qualityVSAvoidsurface roughness
Core Design Contradiction:
Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The patent applies the extraction principle by removing the defective outer layer (clad) from the glass article after molding. The sacrificial clad layer, which contains the surface defects and molding imperfections, is selectively removed through chemical etching or mechanical means, revealing the pristine core glass surface underneath without requiring extensive polishing.

Inventive Principle:
Principle #2Taking out (Extraction)

3Ease of manufacture

If a uniform glass composition is used, then manufacturing simplicity is maintained, but surface defects cannot be selectively removed

Engineering Contradiction:
Improvemanufacturing simplicityVSAvoidsurface defect removal capability
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent applies composite materials by creating a laminated glass structure consisting of a core glass layer and an outer sacrificial clad layer with different chemical compositions. The clad layer has a higher content of alkali metal oxides and lower silicon dioxide content compared to the core, making it more susceptible to chemical etching. This compositional difference enables selective removal of the clad layer while preserving the core glass, achieving both manufacturing feasibility and surface quality improvement.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent applies local quality by creating a glass article with non-uniform composition - a core layer with one composition and an outer clad layer with a different composition optimized for sacrificial removal. The clad layer is specifically designed with higher alkali metal oxide content (Na2O, K2O, Li2O) and lower SiO2 content, making it chemically distinct and removable while the core maintains its structural integrity and optical properties.

Inventive Principle:
Principle #3Local quality

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

Enables the production of defect-free glass articles with smooth surfaces without the need for extensive polishing or grinding, extending the life of forming units and simplifying the manufacturing process.

Implementation Method 1

A degradation rate of the clad glass composition in a reagent is greater than a degradation rate of the core glass composition in the reagent

Methodology Applied
Scientific EffectChemical degradation: Chemical Bonding

Data Source

PatentEP3116834B1Glass article and method for forming the same
Publication Date: 2021.06.02 CORNING INC
  • EP3116834B1 patent drawingFigure 1~5
  • EP3116834B1 patent drawingFigure 2
  • EP3116834B1 patent drawingFigure 3

AI summary

A method includes forming a glass article. The glass article includes a core and a clad adjacent to the core. The core includes a first glass composition. The clad includes a second glass composition different than the first glass composition. A degradation rate of the second glass composition in a reagent is greater than a degradation rate of the first glass composition in the reagent.