Laser Peening Nozzle Straightening for Stable Bubble-Free Flow

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Solution Overview

Problem

Laser peening processing is hindered by air bubbles in the liquid flow, which attenuate the laser beam energy and disrupt the optical path, leading to insufficient irradiation energy and reduced processing effectiveness.

Innovation Solution

A laser peening processing apparatus with a nozzle featuring a straightening part, such as a cylindrical structure or straightening vane, to stabilize the liquid flow and prevent air entrainment, ensuring a stable liquid column and minimizing air bubble generation, combined with a tilting structure to reduce stagnation and optimize liquid flow direction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If liquid is injected from a nozzle towards a surface to be processed, then the surface can be covered with liquid for laser peening, but disturbance in the liquid flow causes air to be involved and air bubbles to generate

Engineering Contradiction:
Improveliquid flow stabilityVSAvoidair bubble generation
Core Design Contradiction:
ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent applies preliminary action by equipping the nozzle with a straightening part that pre-straightens the liquid flow before it reaches the processing area. This preliminary straightening prevents air entrainment and bubble formation during the liquid's contact with the workpiece surface, ensuring stable optical path conditions for laser peening.

Inventive Principle:
Principle #10Preliminary action

2Illumination intensity

If air bubbles are generated in the optical path of laser, then laser light irregularly reflects on the air bubbles, but the sufficient irradiation energy of laser cannot be obtained

Engineering Contradiction:
Improvelaser irradiation energyVSAvoidlaser energy attenuation
Core Design Contradiction:
Illumination intensityVSLoss of energy

Solution Approach 1:

The patent uses the straightening part as an intermediary device between the liquid supply source and the workpiece surface. This intermediary component modifies the liquid flow characteristics by straightening it, thereby preventing air bubble formation in the optical path and ensuring that laser energy is not attenuated by bubble-induced irregular reflections.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Reliability

If a valve is installed on a pipe for supplying liquid to remove air bubbles, then air bubbles can be removed from the liquid, but the device complexity increases

Engineering Contradiction:
Improveair bubble removalVSAvoidvalve installation
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges the air bubble removal function into the nozzle structure itself by incorporating a straightening part. This integration eliminates the need for separate valves or external air removal devices, achieving reliable air bubble prevention while maintaining simple device architecture.

Inventive Principle:
Principle #5Merging (Combining)

4Manufacturing precision

If the optical path of a laser beam is interrupted due to air bubbles, then the energy of the laser beam is attenuated, but laser peening processing cannot be performed with the strictly set energy

Engineering Contradiction:
Improvelaser energy precisionVSAvoidprocessing effectiveness
Core Design Contradiction:
Manufacturing precisionVSReliability

Solution Approach 1:

The straightening part performs preliminary action by pre-conditioning the liquid flow to eliminate disturbances before the laser beam passes through. This ensures that the optical path remains clear of air bubbles, allowing laser peening to be performed with the strictly set energy required for effective processing.

Inventive Principle:
Principle #10Preliminary action

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 solution reduces energy attenuation caused by air bubbles, allowing for more effective laser peening by maintaining a stable liquid column and ensuring sufficient laser energy reaches the workpiece surface, thereby improving the strength and fatigue characteristics of the processed surface.

Implementation Method 1

a laser oscillator (2) which oscillates a laser light; and a nozzle (3) which focuses the laser light and irradiates a surface to be processed of a workpiece (W) with the focused laser light

Methodology Applied
Scientific EffectLaser: Laser

Implementation Method 2

When a focused laser beam is radiated on a surface to be processed of a workpiece covered with liquid, plasma which is generated by the irradiation of the laser beam can be confined in the liquid

Methodology Applied
Scientific EffectPlasma: Plasma

Implementation Method 3

As a result, pressure of a shock wave is applied to the surface to be processed. Thereby, compression stress generated inside the workpiece can be made to remain as residual stress

Methodology Applied
Scientific EffectShock wave: Shock Wave

Data Source

PatentEP3572181B1Laser peening device and laser peening methods
Publication Date: 2022.06.22 SUBARU CORP
  • EP3572181B1 patent drawingFigure 1
  • EP3572181B1 patent drawingFigure 2
  • EP3572181B1 patent drawingFigure 3

AI summary

According to one embodiment, a laser peening processing apparatus includes: a laser oscillator; and a nozzle. The laser oscillator oscillates a laser light. The nozzle focuses the laser light and irradiates a surface to be processed of a workpiece with the focused laser light while flowing a liquid toward the surface to be processed. A straightening part that straightens a flow of the liquid is disposed on the nozzle. Furthermore, according to one embodiment, a laser peening processing method includes: oscillating a laser light; manufacturing a product or a semi-product by focusing the laser light and irradiating a surface to be processed of a workpiece with the focused laser light toward while flowing a liquid on the surface; and straightening the liquid using a straightening structure.