Automated Scarf Joint Formation for Composite Repair

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Solution Overview

Problem

Existing methods for restoring composite structures with out-of-tolerance areas are labor-intensive, inaccurate, and unpredictable, relying on manual skill and requiring multiple steps for material removal and patching.

Innovation Solution

A method and apparatus using a machine tool with a programmable numerical controller, video camera, and non-destructive inspection scanner to iteratively locate and remove out-of-tolerance areas, forming a scarf joint for patch bonding, allowing for precise and consistent material removal.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If manual removal of composite material is performed by a skilled technician using a handheld grinder, then the material can be removed to restore the structure, but the process becomes labor intensive and the accuracy depends on technician expertise leading to inconsistent results

Engineering Contradiction:
Improveaccuracy of material removalVSAvoidlabor intensity
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

The patent replaces the manual mechanical grinding process with an automated machine tool system that uses computer-controlled cutting tools to remove composite material. This substitution eliminates the dependency on technician skill while providing consistent, repeatable results through programmed tool paths and automated control systems.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The system incorporates automated inspection capabilities that allow the machine to identify out-of-tolerance areas and self-correct by adjusting the material removal process accordingly. The feedback loop between inspection and machining enables the system to autonomously achieve the desired geometric tolerance without continuous manual intervention.

Inventive Principle:
Principle #25Self-service

2Reliability

If manual material removal is used to eliminate out-of-tolerance areas, then the composite structure can be restored, but the process is time-consuming and requires multiple manual steps

Engineering Contradiction:
Improverestoration qualityVSAvoidrework time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The system performs preliminary inspection and planning before material removal begins. The machine tool path is pre-programmed based on the identified out-of-tolerance areas, and the automated process executes the restoration without the multiple manual setup and adjustment steps required by traditional methods, significantly reducing total rework time.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The automated machine tool system operates continuously to remove material according to the programmed tool path, eliminating the start-stop nature of manual work. The integrated inspection and machining capabilities allow the process to flow continuously from identification to restoration without breaking for manual repositioning or tool changes.

Inventive Principle:
Principle #20Continuity of useful action

3Productivity

If a machine tool with programmable numerical controller is used to remove material, then rapid and accurate removal is achieved, but the device complexity increases

Engineering Contradiction:
Improvematerial removal speedVSAvoidsystem complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The machine tool system is designed to perform multiple functions including inspection, material removal, and verification within a single integrated platform. This multi-functionality reduces the need for separate manual operations and equipment, justifying the increased device complexity through consolidated capabilities that improve overall productivity and accuracy.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The system incorporates feedback mechanisms where inspection data from the out-of-tolerance areas is fed back into the control system to automatically adjust the material removal process. This closed-loop control enables the complex machine tool to self-optimize its performance, achieving rapid and accurate results while reducing the need for complex manual programming and adjustment procedures.

Inventive Principle:
Principle #23Feedback

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

Enables rapid, accurate, and predictable removal of out-of-tolerance areas in composite structures, minimizing manual effort and ensuring consistent restoration results.

Implementation Method 1

A machine head operated in a user-facilitated manner by a programmable numerical controller may include a video camera to allow for video scanning of the structure in order to locate out-of-tolerance areas.

Methodology Applied
Scientific EffectVideo scanning: Photography

Implementation Method 2

The machine head may remove material from the structure based upon the location of additional out-of-tolerance areas revealed by the video scan.

Methodology Applied
Scientific EffectAbrasion: Abrasion

Data Source

PatentEP2442941B2User-facilitated material removal in composite structures
Publication Date: 2018.05.30 THE BOEING CO
  • EP2442941B2 patent drawingFigure 1~3B
  • EP2442941B2 patent drawingFigure 4
  • EP2442941B2 patent drawingFigure 5

AI summary

A method of removing an out-of-tolerance area in a composite structure comprises determining the location of the out-of-tolerance area and selecting a volume of the composite structure to be removed based on the location of the out-of-tolerance area. The method may further include programming a machine tool to remove the volume and to pause after removal of each one of a quantity of layers of the volume. The method may additionally include removing one of the layers using the programmed machine tool. The method may further include restoring the volume removed using the programmed area removal digital definition.