Laser Cutting Gas Resonance for Cleaner Melt Ejection

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Solution Overview

Problem

Existing methods for drilling or cutting using laser radiation often result in rough surfaces and residue formation due to inefficient removal of molten or vaporized material, leading to issues like dross and burr formation, and lack clear instructions for optimizing excitation frequencies in the removal process.

Innovation Solution

Modulating process parameters, such as gas flow and laser beam properties, with resonant frequencies matching the natural frequency of the gas volume in the ablation zone to enhance the ejection of molten material, utilizing principles similar to whistle formation to increase frictional forces and efficiency of melt expulsion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional gas flow is used to remove ablation products, then material removal is achieved, but rough surfaces and residue formation occur due to inefficient expulsion

Engineering Contradiction:
Improvesurface qualityVSAvoidmaterial removal efficiency
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

The patent applies ultrasonic vibration (mechanical vibration) to the cutting beam or workpiece at frequencies between 20-100 kHz to enhance material ejection from the ablation zone. This vibration creates resonant waves in the molten material, significantly improving expulsion efficiency and reducing surface roughness compared to conventional static gas flow methods.

Inventive Principle:
Principle #18Mechanical vibration

Solution Approach 2:

The patent employs periodic modulation of process parameters including gas pressure, gas flow rate, and laser power at specific frequencies (20-100 kHz) to synchronize with the natural resonance frequency of the ablation zone. This periodic action creates standing waves that enhance material ejection and prevent residue formation on cut surfaces.

Inventive Principle:
Principle #19Periodic action

2Productivity

If gas pressure is increased to improve material ejection, then removal efficiency increases, but gas consumption and process costs increase

Engineering Contradiction:
Improvematerial ejection efficiencyVSAvoidgas consumption
Core Design Contradiction:
ProductivityVSQuantity of substance

Solution Approach 1:

The patent changes the frequency parameter of gas flow modulation to match the resonant frequency (20-100 kHz) of the ablation zone, transforming conventional continuous gas flow into a resonantly modulated flow. This parameter change enables efficient material ejection at lower overall gas consumption by utilizing resonant amplification rather than relying solely on high static pressure.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent applies periodic modulation of gas pressure and flow rate at ultrasonic frequencies (20-100 kHz) to create resonant waves in the ablation zone. This periodic gas delivery is more efficient than continuous high-pressure gas flow, achieving superior material ejection with reduced overall gas consumption.

Inventive Principle:
Principle #19Periodic action

3Productivity

If laser power is increased to improve cutting speed, then productivity increases, but surface quality deteriorates due to excessive melting and residue

Engineering Contradiction:
Improvecutting speedVSAvoidsurface roughness
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The patent employs periodic modulation of laser power at ultrasonic frequencies (20-100 kHz) to synchronize with the resonant frequency of the ablation zone. This periodic laser delivery prevents excessive melting by allowing periodic ejection of molten material, maintaining high cutting speeds while producing smooth surfaces free of dross and burrs.

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The patent applies ultrasonic vibration to the laser processing system to enhance the ejection of molten material from the ablation zone. This vibration mechanism enables higher laser powers to be used for increased cutting speed while preventing surface quality deterioration through resonant material expulsion.

Inventive Principle:
Principle #18Mechanical vibration

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 results in lower roughness depths of cut flanks, reduced gas consumption, and improved processing quality, particularly for metallic materials like stainless steel, by effectively expelling melt with increased frictional forces and resonant wave induction.

Implementation Method 1

drilling or cutting by removing meltable or vaporizable material from a workpiece by absorbing laser radiation

Methodology Applied
Scientific EffectLaser radiation absorption: Absorption (EM radiation)

Implementation Method 2

a laser beam is directed onto a workpiece, which converts the workpiece material into a fluid state

Methodology Applied
Scientific EffectLaser heating: Laser

Implementation Method 3

The process gas flow is responsible for the removal of the ablation products through friction and pressure forces

Methodology Applied
Scientific EffectGas flow friction: Friction

Implementation Method 4

The process gas flow is responsible for the removal of the ablation products through friction and pressure forces

Methodology Applied
Scientific EffectGas pressure: Pressure Increase

Implementation Method 5

vapor pressure gradients generated on the surface of the ablation zone by the laser radiation can be used for the removal of ablation products

Methodology Applied
Scientific EffectVapor pressure gradient: Pressure Gradient

Implementation Method 6

vaporizable material from a workpiece by absorbing laser radiation

Methodology Applied
Scientific EffectEvaporation: Evaporation

Implementation Method 7

one or more process parameters are modulated with the fundamental natural frequency of the gas volume spatially limited by a wall in the region of the removal zone

Methodology Applied
Scientific EffectResonance: Resonance

Implementation Method 8

The component or an added filler material is made to oscillate at a frequency of 15 kHz up to the area of the molten phase

Methodology Applied
Scientific EffectUltrasonic vibration: Ultrasonic Vibration

Data Source

PatentEP3986661B1Method for boring or cutting by removing meltable or vapourisable material of a workpiece
Publication Date: 2023.08.02 FRAUNHOFER GESELLSCHAFT ZUR FORDERUNG DER ANGEWANDTEN FORSCHUNG EV
  • EP3986661B1 patent drawingFigure 1A~1B
  • EP3986661B1 patent drawingFigure 2A~2B
  • EP3986661B1 patent drawingFigure 3~4

AI summary

The invention relates to a method for boring or cutting by removing meltable or vapourisable material of a workpiece (2) by means of laser radiation absorption, melted and/or vapourised material being transported away out of the forming bore hole (1), the forming cutting kerf or the forming cutting slit (1), defined as the removal zone, by a gas flow (6). One or more method parameters are modulated by the fundamental natural frequency of the gas volume spatially delimited by a forming wall in the region of the removal zone, by higher harmonics thereof or by a mixture thereof, in order to thereby support the transportation of the material out of the forming removal zone.