Angled Edge Rolls for Glass Ribbon Width Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The fusion downdraw process for glass sheet production results in sheet width attenuation and variation due to lateral contraction and edge bead formation, leading to unstable ribbon shapes and difficulties in bending the glass to desired curvatures.
Innovation Solution
The use of edge rolls oriented at specific angles and positions during the glass drawing process to contact the glass ribbon, reducing sheet width attenuation and variation by creating parallel velocity contours and minimizing thickness differences between the beads and the center of the sheet.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional horizontal edge rolls are used in the fusion downdraw process, then the glass ribbon can be pulled and cooled, but sheet width attenuation and edge bead formation occur due to lateral contraction
Solution Approach 1:
The patent applies asymmetry by orienting the edge rolls at specific angles (e.g., 45 degrees) relative to the horizontal plane, creating asymmetric contact points on the glass ribbon edges. This asymmetric configuration generates velocity contours that counteract the natural lateral contraction of the viscous glass, preventing sheet width attenuation and edge bead formation while maintaining ribbon shape stability throughout the drawing process.
2Productivity
If the glass ribbon is allowed to cool and become rigid for pulling, then the sheet can be drawn, but lateral contraction occurs in the viscous region causing width loss
Solution Approach 1:
The patent implements preliminary action by positioning the angled edge rolls upstream in the viscous region of the drawing process, before significant lateral contraction occurs. The rolls pre-establish parallel velocity contours and prevent width attenuation proactively, rather than attempting to correct width loss after it occurs. This allows the glass to be pulled at optimal rates while maintaining precise sheet width control.
3Device complexity
If edge rolls are oriented horizontally, then the setup is simple, but they cannot prevent lateral contraction and sheet width variation
Solution Approach 1:
The patent applies parameter changes by modifying the orientation angle of the edge rolls from the conventional horizontal (0 degrees) to specific angled configurations (e.g., 45 degrees). This parameter change fundamentally alters the velocity profile and contact mechanics, enabling the rolls to prevent lateral contraction and achieve superior sheet width control. The angular orientation transforms the edge rolls from passive support elements to active width-control devices.
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 produces glass sheets with widths approaching or exceeding the original ribbon width, reduced bead thickness, and improved stability by mitigating sheet width variation and edge bead formation, resulting in more consistent and usable glass products.
Implementation Method 1
contact the edges of a viscous ribbon of glass
Implementation Method 2
As the glass ribbon descends from the root of the isopipe, it cools to form a solid, elastic glass ribbon
Implementation Method 3
The sheet as it evolves decreases in thickness under the forces of gravity
Data Source
AI summary
Disclosed herein are apparatuses and methods for drawing sheet glass. More particularly, one or more sets of edge rolls can be configured to have a rotation axis angled away from a line orthogonal to the direction of flow of a ribbon of glass and positioned so as to contact the glass in the viscous region of the draw. Through control over the orientation and position of the one or more sets of edge rolls, sheet width attenuation may be eliminated, thickness of the beads that form along the edges of the glass sheet may be reduced, and instabilities associated with sheet width variation may be eliminated.