Convex Edge Glass with Furrows for Fracture Resistance
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Solution Overview
Problem
Thin sheet glass elements are prone to fractures under bending load due to weak edges, with existing edge processing methods focusing on chamfering or C-cuts rather than enhancing edge strength, leading to unpredictable fracture probabilities.
Innovation Solution
A sheet glass element with a convexly curved edge surface featuring furrows that are longer than their width and depth, processed using an abrasive tool with a defined cutting edge, reducing stress intensity at crack ends and increasing overall strength by influencing crack interactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If thin sheet glass elements are processed with conventional edge methods (chamfering or C-cuts), then manufacturing simplicity is maintained, but edge strength is insufficient leading to high fracture probability under bending load
Solution Approach 1:
The patent applies curvature to the edge surface by creating a convexly curved edge with a radius of curvature between 0.05 mm and 0.5 mm. This spherical/curved geometry eliminates sharp corners and stress concentration points, significantly improving edge strength and fracture resistance while maintaining manufacturing feasibility through specialized grinding or polishing processes
Solution Approach 2:
The patent applies different surface qualities to different regions: the edge surface is convexly curved with controlled roughness, while the main glass surfaces remain flat and smooth. This localized differentiation optimizes each region for its specific function - the curved edge for strength and the flat surfaces for optical or structural requirements
2Weight of moving object
If thin sheet glass elements are used (thickness ≤ 700 μm), then weight and flexibility are improved, but fracture probability under load increases due to weak edges
Solution Approach 1:
By applying convex curvature to the edges of thin glass elements, the patent eliminates stress concentration at sharp corners, which is the primary failure initiation point. This allows thin glass (≤ 700 μm) to achieve sufficient fracture resistance for practical applications while maintaining the weight and flexibility advantages of thin design
Solution Approach 2:
The patent changes the geometric parameter of the edge from a sharp corner (zero radius) to a convex curve with radius 0.05-0.5 mm. This parameter change fundamentally alters the stress distribution, allowing thin glass elements to withstand bending loads that would otherwise cause fracture
3Reliability
If edge processing is performed to increase strength, then fracture resistance improves, but manufacturing time and cost increase
Solution Approach 1:
The convex edge curvature can be created in a single grinding or polishing pass using appropriately shaped tools, avoiding the need for multiple sequential operations. This maintains manufacturing efficiency while achieving the strength benefits of curved edges
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 significantly enhances the strength and fracture resistance of thin glass sheets, particularly those under 700 micrometers thick, by reducing fracture probability and extending service life under bending loads, with measured strengths exceeding 500 MPa and high Weibull modulus.
Implementation Method 1
processed using an abrasive tool with a defined cutting edge
Data Source
AI summary
Thin glass elements with improved edge strength are provided—from a sheet glass element that has two opposite parallel faces and an edge connecting the faces. The sheet glass element has a thickness of at most 700 μm. At least a portion of the edge is defined by an edge surface portion that is convexly curved, so that at least one of the faces merges into the edge surface portion, wherein a curved arc of the edge surface portion has a length that is at least 1/30 of the thickness of the sheet glass element. In the region of the convex curvature, the edge surface portion has indentations in the form of furrows.