Chemically Strengthened Glass for Bend Forming
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing chemically strengthened glasses face issues with cracking and poor forming precision during bend forming, particularly due to thermal stress and variations in shape, which are exacerbated by the demand for higher definition and waterproofness in display devices.
Innovation Solution
A chemically strengthened glass with a Young's modulus of 70 GPa or more, specific thermal expansion coefficients, and a viscosity profile that minimizes thermal stress, combined with a lithium aluminosilicate composition and a chemical strengthening process that includes ion exchange treatments to create a compressive stress layer, is developed to enhance scratch resistance and forming precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If a glass sheet is bend-formed by heating, then a curved surface shape can be produced, but thermal stress is generated causing cracking of the glass sheet
Solution Approach 1:
The patent applies parameter changes by precisely controlling the glass composition parameters (X1+X2+X3 ≤ 1760) and thermal properties (viscosity-temperature characteristics) to enable bend forming at lower temperatures with reduced thermal stress. This resolves the contradiction by modifying the material parameters to tolerate the forming process without cracking.
Solution Approach 2:
The patent implements preliminary action by pre-heating the glass sheet to a specific temperature range (softening temperature Ts - 50°C to Ts - 100°C) before bend forming. This preliminary heating prepares the glass in advance, reducing thermal shock and stress during the actual forming process, thereby preventing cracking while achieving the curved shape.
2Shape
If a glass sheet is bend-formed, then a curved surface shape can be produced, but the shape of the formed glass sheet varies
Solution Approach 1:
The patent uses parameter changes by optimizing the glass composition (X1+X2+X3 ≤ 1760) and viscosity characteristics to ensure uniform deformation during bend forming. This control over material parameters ensures consistent shape reproduction and high forming precision while maintaining the desired curved surface geometry.
3Shape
If the glass is subjected to three-dimensional forming, then a curved surface shape can be achieved, but the glass is prone to easy cracking during the process
Solution Approach 1:
The patent applies parameter changes by controlling the glass composition parameters (X1+X2+X3 ≤ 1760) and thermal expansion characteristics to reduce internal stress during three-dimensional forming. This resolves the contradiction by modifying material parameters to enhance strength and cracking resistance while achieving the curved shape.
Solution Approach 2:
The patent implements preliminary action by pre-heating the glass to a controlled temperature range before three-dimensional forming. This advance preparation reduces thermal shock and internal stress during the forming process, preventing cracking while achieving the desired curved surface shape.
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
The solution results in a high-strength, crack-resistant glass with improved forming precision and safety, suitable for curved surfaces in display devices, by reducing thermal stress and maintaining shape integrity during the bend forming process.
Implementation Method 1
chemical strengthening process that includes ion exchange treatments to create a compressive stress layer
Implementation Method 2
thermal stress is generated by heating the glass sheet
Implementation Method 3
thermal stress is generated by heating the glass sheet, which sometimes causes cracking of the glass sheet
Implementation Method 4
X2 is a numeral value equivalent to a value of a temperature Tf at which a viscosity of the glass reaches 100 MPa·s
Data Source
AI summary
A glass for chemical strengthening has a Young's modulus E of 70 GPa or more. The glass satisfies X1+X2+X3 being 1760 or less. Here, X1 is a numerical value equivalent to a value [unit: kPa/° C.] obtained by multiplying the Young's modulus E by an average coefficient α of thermal expansion at 50° C. to 350° C., X2 is a numeral value equivalent to a value of a temperature Tf [unit: ° C.] at which a viscosity of the glass reaches 100 MPa·s, and X3 is a numerical value equivalent to a value of a difference [unit: 105 Pa·s] between the viscosity (100 MPa·s) at the Tf and a viscosity η+10 at a temperature 10° C. higher than the Tf.