Acoustic Panel Laser Perforation With Plasma Feedback Control

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Solution Overview

Problem

Existing laser machining processes for forming perforations in acoustic panels often damage the core walls and adhesive bonds, compromising the structural integrity of the panel.

Innovation Solution

A manufacturing process that uses a laser system combined with a plasma sensor system to detect plasma emissions from different materials, allowing the controller to adjust the perforation process to avoid damaging the core walls and adhesive bonds by terminating the perforation when specific plasma signatures are detected.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If laser machining is used to form perforations in the first skin, then the perforation process is efficient and precise, but the core walls and adhesive bonds may be damaged or weakened

Engineering Contradiction:

Improveperforation formation efficiencyVSAvoidstructural integrity of core walls and adhesive bonds

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The system uses a plasma sensor to detect plasma emissions during laser machining and provides real-time feedback to the controller. When the sensor detects plasma emissions indicating the laser has reached the core walls or adhesive bonds, the controller automatically adjusts or terminates the laser process to prevent damage, thus resolving the contradiction between efficient perforation formation and structural integrity preservation

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system performs preliminary detection of material layers using plasma emissions before the laser can cause damage. By detecting the presence of core walls or adhesive bonds through plasma sensor readings in advance, the system can prepare to adjust laser parameters or terminate the process, preventing structural damage before it occurs

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 process effectively reduces damage to the core walls and adhesive bonds, maintaining the structural integrity of the acoustic panel while forming perforations.

Implementation Method 1

The perforations may alternatively be formed in the first skin using laser machining

Methodology Applied

Scientific EffectLaser ablation: Laser Ablation

Implementation Method 2

A plasma sensor system senses plasma emissions produced during laser ablation of the panel materials

Methodology Applied

Scientific EffectPlasma emission detection: Plasma

Data Source

PatentEP3520950B1Controlling perforating of an acoustic panel based on sensed optical emissions

Publication Date: 2025.09.17 ROHR INC

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AI summary

A manufacturing process is provided that includes steps of: providing a panel (30) comprising a core (54) connected to a first skin (50), wherein the panel (30) is configured with a plurality of cavities (64) extending through the core (54) to the first skin (50); partially forming a first perforation (68A-B) in the first skin (50) using a laser beam (42); operating a sensor (26) to sense optical emissions produced during the partial forming of the first perforation (68A-B); and determining, based on an output of the sensor (26), whether to: continue formation of the first perforation (68A-B) in the first skin (50); or terminate formation of the first perforation (68A-B) in the first skin (50).