Laser Glass Cleaving for Thick Sheets With Stronger Edge Surfaces

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Solution Overview

Problem

Existing laser cleaving methods using CO2 lasers fail to adequately heat the inner portion of thicker glass sheets, leading to degraded end surfaces with microcracks and reduced strength.

Innovation Solution

A method involving the use of CO, Er, or Ho laser light to heat both the surface layer and inner portion of the glass sheet, with a temperature difference of 575°C or more between the irradiation and cooling regions, forming a compressive stress layer to enhance the strength of the end surfaces.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If CO2 laser is used for heating surface layer only, then the cleaving process is simple, but the end surface quality degrades and microcracks form on thicker glass sheets

Engineering Contradiction:

Improvecleaving process simplicityVSAvoidend surface quality

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent changes the laser wavelength parameter from CO2 laser (10.6 μm) to mid-infrared lasers (3-5 μm range) that can penetrate deeper into glass. This parameter change enables effective heating of the inner portion while maintaining surface heating, resolving the contradiction between process simplicity and end surface quality for thicker glass sheets

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent transitions from surface-only heating (two-dimensional surface process) to volumetric heating (three-dimensional interior process) by using lasers with different penetration characteristics. This dimensional change in heating depth allows simultaneous surface and inner portion heating, improving end surface quality without complicating the cleaving process

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Device complexity

If only surface layer is heated, then the heating process is simple, but sufficient thermal stress cannot be generated in the inner portion

Engineering Contradiction:

Improveheating process complexityVSAvoidthermal stress in inner portion

Core Design Contradiction:

Device complexityVSStress or pressure

Solution Approach 1:

The patent changes the laser wavelength parameter to achieve different penetration depths, enabling the laser energy to reach the inner portion of the glass sheet. This generates sufficient thermal stress in the inner portion without increasing device complexity, as the same laser system is used with adjusted parameters

Inventive Principle:

Principle #35Parameter changes

3Stress or pressure

If laser light penetrates deeply to heat inner portion, then thermal stress is sufficient, but surface layer heating may be insufficient

Engineering Contradiction:

Improvethermal stress in inner portionVSAvoidsurface layer temperature

Core Design Contradiction:

Stress or pressureVSTemperature

Solution Approach 1:

The patent merges the benefits of both surface heating and deep penetration by selecting laser wavelengths (3-5 μm) that provide optimal balance. This merging approach ensures sufficient temperature in the surface layer while also generating adequate thermal stress in the inner portion, resolving the contradiction between surface heating and deep penetration

Inventive Principle:

Principle #5Merging (Combining)

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 a glass sheet with improved strength and reduced defects by forming a continuous compressive stress layer on the edge and end surfaces, effectively preventing breakage.

Implementation Method 1

heating a surface layer and an inner portion of the mother glass sheet with laser light in the irradiation region

Methodology Applied

Scientific EffectLaser heating: Laser

Implementation Method 2

a thermal stress (thermal shock) is generated in the mother glass sheet

Methodology Applied

Scientific EffectThermal stress: Thermal Shock

Implementation Method 3

the heated portion is cooled by a refrigerant such as cooling water jetted from a cooling unit

Methodology Applied

Scientific EffectRapid cooling: Cooling

Implementation Method 4

a thermal stress (thermal shock) is generated in the mother glass sheet

Methodology Applied

Scientific EffectThermal shock: Thermal Shock

Implementation Method 5

setting a difference ΔT between a highest temperature in the irradiation region and a lowest temperature in the cooling region to 575° C. or more

Methodology Applied

Scientific EffectThermal gradient: Temperature Gradient

Implementation Method 6

a compressive stress layer is formed on an edge portion of the surface of the glass sheet

Methodology Applied

Scientific EffectThermal stress: Thermal Shock

Data Source

PatentUS12509385B2Glass plate and method for manufacturing glass plate

Publication Date: 2025.12.30 NIPPON ELECTRIC GLASS CO LTD

AI summary

A method of manufacturing a glass sheet includes: an initial crack forming step of forming an initial crack on a mother glass sheet (MG); and a cleaving step of causing a crack (CR) to propagate in a direction along a preset cleaving line (CL) and in a thickness direction of the mother glass sheet (MG), the crack starting from the initial crack, through use of a thermal stress generated by heating of an irradiation region (SP) of laser light (L) and cooling of a cooling region (CP). The cleaving step includes heating a surface layer (SL) and an inner portion (IL) of the mother glass sheet (MG) with the laser light (L) in the irradiation region (SP) and setting a difference ΔT between a highest temperature in the irradiation region (SP) and a lowest temperature in the cooling region to 575° C. or more.