Glass Separation Using Stress-Guided Crack Control

Solution Overview

Problem

Existing glass separation methods fail to control the course of cracks accurately, leading to rough separation faces and edges with low strength, making them susceptible to damage and crack propagation.

Innovation Solution

A method involving the formation of tensile and compressive stress zones within the glass material using a line focus to guide the crack along a predetermined separation face, preventing crack deviation and enhancing edge strength and surface smoothness.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional separation methods (thermal laser beam separation, mechanical scribing, laser scribing) are used, then separation can be performed, but the course of cracks cannot be controlled accurately leading to rough separation faces and low edge strength

Engineering Contradiction:

Improvecontrol of separation face courseVSAvoidedge strength

Core Design Contradiction:

Manufacturing precisionVSStrength

Solution Approach 1:

The patent applies preliminary action by creating a scratch line on the glass surface before separation. This scratch line serves as a predefined path that guides the crack propagation during subsequent separation processes, ensuring the crack follows the desired separation face course rather than deviating randomly. The scratch line is created as a preliminary modification that controls where the crack will initiate and propagate.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent employs parameter changes by applying compressive stress to the glass element after the scratch line is created. This stress modification creates a stress field that confines the crack propagation to the scratch line region. By changing the stress parameters (applying compression), the crack path is controlled to follow the scratch line, resulting in a precise separation face with smooth edges and high strength.

Inventive Principle:

Principle #35Parameter changes

2Manufacturing precision

If laser filamentation method is used to remove material along separation face, then separation can be achieved, but roughness value increases and tear line deviates from perforation line

Engineering Contradiction:

Improveseparation face accuracyVSAvoidprocess complexity

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent applies preliminary action by creating a scratch line on the glass surface before separation. This scratch line serves as a predefined path that guides the crack propagation during subsequent separation processes, ensuring the crack follows the desired separation face course rather than deviating randomly. The scratch line is created as a preliminary modification that controls where the crack will initiate and propagate.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent employs parameter changes by applying compressive stress to the glass element after the scratch line is created. This stress modification creates a stress field that confines the crack propagation to the scratch line region. By changing the stress parameters (applying compression), the crack path is controlled to follow the scratch line, resulting in a precise separation face with smooth edges and high strength.

Inventive Principle:

Principle #35Parameter changes

3Manufacturing precision

If ablation methods are used to iteratively remove glass material, then separation can be performed, but the process takes a long time and causes large damage zone

Engineering Contradiction:

Improveseparation face qualityVSAvoidseparation speed

Core Design Contradiction:

Manufacturing precisionVSProductivity

Solution Approach 1:

The patent applies the taking out principle by extracting only the essential function of material removal. Instead of using iterative ablation to remove material, the patent creates a scratch line that defines the separation path and then uses stress-induced crack propagation to separate the glass. This extracts the separation function from the material removal process, achieving fast separation without large damage zones while maintaining precise separation face quality.

Inventive Principle:

Principle #2Taking out (Extraction)

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 method allows for precise control of the separation face, reducing roughness and increasing edge strength, enabling efficient and reliable glass separation without material removal or contamination, and can be integrated into existing facilities.

Implementation Method 1

controlling at least one line focus within the glass body in such a way that at least one tensile stress zone and/or at least two compressive stress zones are formed in the glass material along the separation face

Methodology Applied

Scientific EffectStress zone formation:

Implementation Method 2

controlling at least one line focus within the glass body

Methodology Applied

Scientific EffectLaser heating: Laser

Implementation Method 3

laser-based thermal cutting (laser based thermal shock cutting)

Methodology Applied

Scientific EffectThermomechanical stress: Thermal Shock

Data Source

PatentUS12110247B2Method for separating a glass element and glass sub-element

Publication Date: 2024.10.08 SCHOTT AG

AI summary

The present disclosure relates to a method for at least section-wise separating a glass element into at least two glass sub-elements along a separation face and a glass sub-element which is manufactured and/or can be manufactured in particular by the method according to the disclosure.