Tempering Glass Sheets with Localized Cooling Zones
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Thin glass sheets with a thickness of not more than 4 mm often exhibit bi-stability and warping during the tempering process, making it difficult to maintain planarity and achieving uniform surface compression stress, which is critical for safety and strength.
Innovation Solution
A method involving a tempering process where glass sheets are heated to a specific temperature and quenched using cooling air jets with a blasting pressure of at least 6 kPa and a blasting distance of not more than 30 mm, with a subarea of weakened cooling capacity to delay quenching of the intermediate portion relative to the side portions, ensuring even surface compression stress distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional quenching with uniform cooling capacity is applied to thin glass sheets, then surface compression stress can be achieved, but bi-stability and warping occur causing loss of planarity
Solution Approach 1:
The quenching device implements different cooling capacities in different zones: side portions receive strong cooling to generate surface compression stress, while the intermediate portion receives weakened cooling to prevent warping and maintain planarity. This local differentiation of cooling intensity resolves the contradiction between achieving strength and maintaining shape.
2Strength
If cooling capacity is increased to achieve higher surface compression stress, then glass strength improves, but warping and bi-stability increase
Solution Approach 1:
By applying localized weakened cooling capacity specifically to the intermediate portion while maintaining strong cooling at the side portions, the invention achieves uniform surface compression stress distribution without inducing bi-stability. The local quality adjustment prevents the harmful thermal stresses that cause warping.
3Ease of manufacture
If uniform cooling is applied across the entire glass sheet, then processing is simple, but non-uniform surface compression stress distribution occurs leading to warping
Solution Approach 1:
The quenching device incorporates zones with different cooling capacities (strong cooling for side portions, weakened cooling for intermediate portion) to achieve uniform surface compression stress distribution. This localized approach improves manufacturing precision while maintaining relative process simplicity through automated zone control.
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 effectively prevents bi-stability and warping, achieving a surface compression stress of at least 100 MPa while maintaining the glass sheet's planarity, enhancing its strength and safety characteristics.
Implementation Method 1
heating a glass sheet to a tempering temperature
Implementation Method 2
conducting a quenching step by blasting cooling air with a blasting pressure of not less than 6 kPa and a blasting distance of not more than 30 mm to both surfaces of the glass sheet
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
A method and an apparatus for tempering glass sheets. A glass sheet is heated to a tempering temperature and quenching is conducted by blasting cooling air to both surfaces of the glass sheet. The quenching of a top surface and a bottom surface of the glass sheet's both side portions (G1) is commenced earlier or is performed at the early stage of quenching more effectively than the quenching of a top surface and a bottom surface of the glass sheet's intermediate portion (G2). As a result, the compression stress required for a desired tempering degree is established on both surfaces of the side portions earlier than on both surfaces of the intermediate portion. In order to achieve this, the cooling air enclosures (4) above and below a glass sheet are provided with a subarea (A) of weakened cooling effect.