Low-Waviness Float Glass Panes Through Viscosity-Controlled Forming
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Solution Overview
Problem
Existing glass sheets exhibit pronounced optical defects, particularly fine waviness, which require further surface working measures like polishing, and there is a need for methods to reduce these defects without additional processing.
Innovation Solution
A method for producing glass sheets with minimal fine waviness by adjusting the viscosity of the glass melt during hot forming, specifically targeting the sum total of the common logarithms of viscosity at the start and end of the hot forming process to be between 11.4 and 11.8, ensuring minimal fine waviness without subsequent surface working.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If surface working measures like polishing are applied to reduce fine waviness, then optical defects are reduced, but additional processing steps and time are required
Solution Approach 1:
The invention applies preliminary action by adjusting the viscosity of the glass melt during the hot forming process itself, rather than allowing fine waviness to develop and then correcting it through subsequent polishing. By controlling viscosity parameters (sum of common logarithms of viscosity at start and end of hot forming to be between 11.4 and 11.8), the glass sheet is formed with minimal fine waviness from the outset, eliminating the need for later surface working steps.
2Manufacturing precision
If the viscosity of glass melt is adjusted during hot forming, then fine waviness is reduced, but process complexity increases
Solution Approach 1:
The invention applies parameter changes by systematically adjusting the viscosity of the glass melt during hot forming. Specifically, the sum of the common logarithms of the viscosity at the start and end of hot forming is controlled to be between 11.4 and 11.8. This parameter control enables the glass to be formed with minimal fine waviness while maintaining a manageable process complexity through defined viscosity targets rather than overly complex real-time adjustment systems.
3Productivity
If glass sheets are produced without surface working, then production time is reduced, but optical defects like fine waviness increase
Solution Approach 1:
The invention applies preliminary action by incorporating surface quality control directly into the hot forming process itself. By controlling the viscosity parameters during forming, the glass sheet emerges with minimal fine waviness already, eliminating the need for subsequent polishing or other surface working steps. This enables high productivity without sacrificing optical quality.
Solution Approach 2:
The invention applies self-service by allowing the glass melt to self-regulate its surface quality through controlled viscosity during hot forming. The viscosity control enables the glass to form its own surface with minimal defects without requiring external intervention through polishing or other surface working processes, thereby achieving both high productivity and high optical quality simultaneously.
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 method results in glass sheets with reduced fine waviness, enhancing their suitability for applications in electronic devices and displays, while maintaining good scratch resistance and chemical stability, without the need for additional surface treatment.
Implementation Method 1
the viscosity of the glass is adjusted in a targeted way in the production method
Data Source
AI summary
The invention relates to a glass pane, in particular a glass pane which is obtained by individualizing a floated glass strip formed by a hot forming process, in particular comprising a borosilicate glass, with a thickness (D) ranging from at least 1.75 mm to maximally 7 mm or a thickness (D) ranging from at least 0.7 mm to 7 mm, in particular from 1.1 mm to maximally 7 mm, and comprising an upper face and a lower face. The glass pane is characterized by a fine waviness of 10 nm to 26 nm, preferably between 10 nm and 15 nm, in at least one direction parallel to the surface of the glass pane on at least one surface of the upper face or the lower face of the glass pane. The invention also relates to an assembly of said glass panes and to methods for producing and using same.