Glass Roll Winding Radius Formula Prevents Static Fatigue
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Solution Overview
Problem
The existing package forms for glass films, such as the glass roll, are susceptible to breakage due to static fatigue caused by tensile stress, especially when stored for long periods, as the minimum winding radius is not optimally regulated, leading to increased stress on the glass film.
Innovation Solution
The glass roll is formed by winding the glass film into a roll with a minimum winding radius that satisfies a specific formula based on the flexural strength obtained from a 3-point bending test, ensuring that the tensile stress does not exceed the flexural strength, thereby preventing breakage from static fatigue. Additionally, the glass film is cut using laser splitting to reduce defects and the thickness is maintained between 1 μm and 200 μm for flexibility and reduced risk of breakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the glass plate is thinned into a glass film to improve flexibility and space saving, then the flexibility and adaptability to curved surfaces are improved, but the glass film becomes more susceptible to breakage due to stress concentration and static fatigue
Solution Approach 1:
The patent applies parameter changes by establishing a specific thickness range (20 μm to 200 μm) and minimum winding radius relationship for the glass film. The formula R ≥ (t/2) × √(E/σ) defines critical parameters (thickness, radius, elastic modulus, strength) to prevent breakage while maintaining flexibility. This resolves the contradiction by optimizing physical parameters to balance flexibility and breakage resistance.
Solution Approach 2:
The patent implements beforehand cushioning by specifying protective packaging arrangements and minimum winding radius requirements before the glass film is used. The packaging structure and winding parameters are designed in advance to prevent stress concentration and static fatigue during storage and transportation, thereby preventing breakage before it occurs.
2Volume of moving object
If the glass film is wound into a roll with a small winding radius to save space, then the volume and transportation efficiency are improved, but the tensile stress increases causing static fatigue and breakage
Solution Approach 1:
The patent resolves this contradiction by establishing a mathematical relationship between winding radius and film thickness through the formula R ≥ (t/2) × √(E/σ). This allows determination of the minimum safe winding radius for any given thickness, enabling compact packaging while preventing static fatigue. The parameter optimization balances space savings with reliability.
3Ease of manufacture
If conventional packaging forms are used for glass films, then the packaging process is simple, but the glass film breaks easily due to stress concentration at contact points
Solution Approach 1:
The patent applies beforehand cushioning by designing specific packaging structures with protective layers and distributing the glass film weight across multiple support points. The packaging is configured in advance to prevent stress concentration at contact points, thereby preventing breakage while maintaining manufacturing simplicity.
Solution Approach 2:
The patent transitions from conventional flat stacking (2D arrangement) to rolled configuration (3D cylindrical arrangement). This dimensional change allows the glass film to be packaged in a compact roll form while distributing stresses uniformly through the curved geometry, preventing the stress concentration that occurs in flat stacking arrangements.
4Adaptability or versatility
If the glass film is made thinner to improve flexibility, then the adaptability to curved surfaces is improved, but the gas barrier property deteriorates making it unsuitable for OLED applications
Solution Approach 1:
The patent resolves this contradiction by establishing an optimal thickness range (20 μm to 200 μm) that balances flexibility and gas barrier properties. This parameter optimization ensures the glass film is thin enough for curved surface applications while maintaining sufficient thickness to provide adequate barrier protection against oxygen and water vapor for OLED applications.
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 effectively prevents breakage due to static fatigue, allowing the glass film to be stored for long periods without failure, while also optimizing the size and flexibility of the glass roll for efficient transportation and use in flexible applications.
Implementation Method 1
breakage is more liable to occur. Consequently, a package form used for transportation or the like becomes a major issue... the glass film easily breaks due to its extreme bending or concentration of stress applied on a very fragile lower end portion
Implementation Method 2
the glass film is cut using laser splitting to reduce defects
Data Source
Figure 1~2
Figure 3
Figure 4a~4c
AI summary
Provided is a glass roll formed by winding a glass film into a roll, in which a minimum winding radius of the glass film is optimized. Thus, the glass film is reliably prevented from breaking due to static fatigue, and is able to be stored for long periods. A glass roll (1), which is formed by winding a glass film (2) into a roll, has a configuration in which the glass film has a minimum winding radius (R) satisfying the following relation: R≥(T/2)[(2.3/σ)×E-1], where σ represents flexural strength of the glass film (2) obtained by a 3-point bending test, T represents a thickness of the glass film, and E represents a Young's modulus of the glass film.