Sheet Glass Separation Using Laser Filaments and Thermal Stress
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for separating portions from sheet glass elements along non-rectilinear separation lines are inefficient, often resulting in detrimental cracking and the generation of splinters, making it difficult to achieve clean and precise separation, especially for curved or closed-loop shapes.
Innovation Solution
The method involves producing filamentary damages in the glass element using ultrashort pulse lasers, followed by heating the main part and cooling the portion to create differential thermal expansion, allowing for precise separation without additional auxiliary cuts, thereby minimizing damage and ensuring high edge quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional laser methods are used for separation, then the separation process can be completed, but detrimental cracking and splinter generation occur, reducing edge quality
Solution Approach 1:
The separation process is divided into two distinct stages: first, creating filamentary damages along the separation line using ultrashort pulse lasers, and second, applying thermal stress to propagate cracks along these pre-defined paths. This segmentation allows precise control over where cracks form, preventing random splintering while achieving clean separation along the intended line.
Solution Approach 2:
The ultrashort pulse laser creates a series of filamentary damages along the separation line before the actual separation occurs. These filaments serve as pre-defined crack propagation paths, guiding the subsequent thermal stress-induced cracks to follow the exact desired separation line, thereby preventing detrimental cracking outside the intended area and eliminating splinter generation.
2Ease of manufacture
If additional auxiliary cuts are made to achieve complete separation, then separation can be accomplished, but processing complexity increases and edge quality deteriorates
Solution Approach 1:
The invention changes the physical state and properties of the glass material through controlled thermal stress application. By heating the glass to create thermal expansion and stress, the material's mechanical properties are temporarily altered, allowing complete separation along the filamentary damage lines without requiring additional auxiliary cuts, thus simplifying the overall process while maintaining edge quality.
3Manufacturing precision
If conventional separation methods are applied to complex shapes, then separation can be achieved, but the integrity of glass parts is compromised and flexural strength is reduced
Solution Approach 1:
The invention replaces conventional mechanical separation methods with a combined optical-thermal approach. Ultrashort pulse lasers create precise filamentary damages without mechanical contact, and thermal stress is applied to propagate cracks along these paths. This substitution eliminates mechanical forces that would compromise glass integrity, preserving flexural strength while achieving accurate separation of complex shapes.
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 enables efficient, splinter-free separation of glass portions along complex shapes while maintaining the integrity of both the separated and remaining glass parts, reducing processing complexity and increasing the flexural strength of the glass edges.
Implementation Method 1
A filament is produced by an ultrashort laser pulse which causes self-focusing to take place inside the glass due to the Kerr effect until energy density becomes so high at some point that a plasma is ignited
Implementation Method 2
a plasma is ignited. A plasma explosion occurs, during which the glass undergoes irreversible damage around this plasma generation site
Implementation Method 3
the glass element is heated in the region of the main part so as to cause expansion thereof and/or is cooled in the region of the portion so as to cause contraction thereof
Data Source
AI summary
A method for separating a portion from a sheet glass element having a thickness of at least 2 millimeters along an intended separation line that divides the sheet glass element into the portion and a remaining main part is provided. The method includes producing filamentary damages comprising sub-micrometer hollow channels in a volume of the glass sheet element adjacently aligned along the separation line; and heating and/or cooling the glass sheet element to cause expansion and/or contraction so that the portion detaches from the main part along the separation line. The portion and the remaining main part each remain intact as a whole. The step of producing the filamentary damages includes generating a plasma within the volume with laser pulses of an ultrashort pulse laser; and displacing points of incidence of the laser pulses over a surface of the glass sheet element along the separation line.