Thermal Tempering of Thin Glass Sheets via Conductive Cooling
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Solution Overview
Problem
Current thermal strengthening methods face challenges in achieving full tempering in glass sheets thinner than 3 mm, as they require higher cooling rates and energy consumption, leading to deformation and limitations in achieving significant temperature differentials between the surface and center of thin glass sheets.
Innovation Solution
The process involves positioning glass sheets between heat sinks with controlled gas flows to facilitate thermal conduction over convection, achieving high heat transfer rates without surface contact, allowing for the creation of surface compressive stress and central tension in glass sheets as thin as 0.1 mm.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional convective gas cooling is used to strengthen thin glass sheets, then surface compressive stress is achieved, but the glass sheet deforms and cannot achieve full tempering
Solution Approach 1:
The patent replaces convective cooling (fluid-based) with conductive cooling (solid-based) by using a cooled substrate to cool the glass sheet from the rear surface. This substitution eliminates the deformation issues associated with convective cooling while achieving the necessary surface compressive stress for full tempering in thin glass sheets
Solution Approach 2:
The patent introduces a cooled substrate as an intermediary element between the heat source and the glass sheet. The substrate acts as a heat sink that conducts heat away from the rear surface of the glass, enabling controlled cooling that prevents deformation while achieving the desired stress distribution
2Strength
If higher cooling rates are applied to thin glass sheets to achieve full tempering, then surface compressive stress increases, but energy consumption increases
Solution Approach 1:
The patent replaces high-energy convective cooling with lower-energy conductive cooling through a cooled substrate. The conductive mechanism is more energy-efficient for achieving the same cooling effect, reducing overall energy consumption while maintaining the necessary surface compressive stress levels
Solution Approach 2:
The patent changes the cooling mechanism parameter from convective to conductive, and adjusts the cooling rate to be optimized for thin glass sheets. This parameter change enables achieving full tempering with reduced energy input compared to conventional high-rate convective cooling
3Adaptability or versatility
If conventional thermal strengthening is used on glass sheets thinner than 3 mm, then processing is possible, but full tempering cannot be achieved
Solution Approach 1:
The patent replaces conventional convective cooling with conductive cooling through a cooled substrate, enabling full tempering to be achieved in thin glass sheets (including sheets thinner than 3 mm) that cannot be fully tempered using conventional methods
Solution Approach 2:
The patent changes the cooling mechanism and optimizes processing parameters (heating temperature, cooling rate, substrate temperature) to enable full tempering in thin glass sheets, expanding the adaptability of thermal strengthening processes to include very thin glass while achieving complete tempering behavior
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 method enables the production of highly strengthened thin glass sheets with compressive stresses up to 400 MPa and central tensions over 100 MPa, achieving full tempering behavior without deformation or surface damage, while reducing energy consumption and maintaining surface quality.
Implementation Method 1
cooling the glass sheet by conduction more than by convection
Implementation Method 2
cooling the glass sheet by conduction more than by convection
Data Source
AI summary
A strengthened glass sheet product as well as process and an apparatus for making the product. The process comprises cooling the glass sheet by non-contact thermal conduction for sufficiently long to fix a surface compression and central tension of the sheet. The process results in thermally strengthened glass sheets having improved breakage properties.