Thin Glass Ribbon Drawing With Cool-Edge Rollers for Surface Quality
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Solution Overview
Problem
The production of very thin glasses with thicknesses less than 250 μm is challenging due to high demands on surface quality and thickness uniformity, and existing methods like etching are expensive and time-consuming, while methods producing hollow-cylindrical glass are not suitable for flat applications.
Innovation Solution
A method and apparatus for producing a flat thin glass ribbon by melting glass, drawing it from a tank with tensile forces, cooling it below the glass transition temperature, and using spaced drawing rollers to control thickness, ensuring contact only at temperatures below 500°C to maintain quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If glass is thinned by etching to achieve very thin thickness, then the desired thickness is obtained, but the process becomes expensive and time-consuming
Solution Approach 1:
The invention changes the fundamental parameter of glass thickness control from post-forming etching to in-situ control during the forming process itself. By adjusting drawing speed, temperature, and roller pressure parameters during the drawing process, the desired thin thickness is achieved directly without requiring subsequent etching operations, thereby resolving the contradiction between manufacturing precision and productivity
Solution Approach 2:
The invention extracts and eliminates the etching step from the production process entirely. By achieving the desired thin thickness directly through controlled drawing from the melt, the harmful etching operation is removed, reducing both time consumption and production costs while maintaining the required thickness precision
2Manufacturing precision
If drawing rollers contact hot glass to apply tensile forces, then the glass can be drawn to thin thickness, but the surface quality deteriorates due to contact marks
Solution Approach 1:
The invention applies local quality by differentiating the temperature zones along the glass path. The drawing rollers are positioned in a cooler zone where the glass has lower viscosity and can be drawn without surface marks, while the upper surface maintains higher temperature for quality preservation. This spatial differentiation of temperature zones allows simultaneous achievement of thin thickness and high surface quality
Solution Approach 2:
The invention performs preliminary cooling of the glass ribbon before it reaches the drawing rollers. By pre-cooling the glass in the region where rollers will contact it, the glass achieves optimal viscosity for drawing without leaving marks on the final surface, thus preparing the material in advance for mark-free thinning
3Productivity
If glass is cooled rapidly to increase production speed, then productivity improves, but the glass becomes too brittle and breaks easily
Solution Approach 1:
The invention implements periodic or staged cooling action through multiple cooling zones with progressively different cooling intensities. The glass first undergoes moderate cooling to reduce temperature, then enters a controlled cooling zone that gradually increases cooling rate while monitoring glass strength, allowing the glass to adapt to cooling stresses without becoming too brittle, thus maintaining both productivity and strength
Solution Approach 2:
The invention applies beforehand cushioning by introducing a controlled thermal gradient that gradually increases cooling intensity. Before rapid cooling begins, the glass is pre-cooled at a moderate rate to reduce thermal stress buildup, cushioning the material against shock that would cause brittleness, thereby enabling subsequent faster cooling without compromising strength
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 reliable production of thin glass ribbons with thicknesses of up to 50 μm and low thickness deviation, achieving a fire-polished surface with low roughness and reduced stress, suitable for further processing without breaking.
Implementation Method 1
the thin glass ribbon being cooled after it emerges until it undershoots the glass transition temperature Tg
Implementation Method 2
tensile forces which act in the longitudinal direction, the thin glass ribbon being cooled after it emerges
Data Source
AI summary
A method for producing a flat thin glass ribbon is provided. The method includes the steps of drawing melted glass downward away from a tank in a pulling direction while applying tensile forces which act in the pulling direction to form the thin glass ribbon having a thickness of at most 250 μm and cooling the thin glass ribbon until a temperature of the thin glass ribbon undershoots a glass transition temperature. The tensile forces are transferred to the thin glass ribbon by at least two pairs of drawing rollers. The at least two pairs of drawing rollers are spaced apart transversely to the pulling direction and contact the thin glass ribbon on longitudinal edges of the thin glass ribbon. The thin glass ribbon only makes contact with the at least two pairs of drawing rollers at a position where the temperature of the thin glass ribbon is at most at or below 500° C.