Heated Cutting Wire for Expanded Material Removal in Composite Tooling

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Solution Overview

Problem

Complex shapes in composite part manufacturing often make it difficult to effectively clamp composite layers against a mold using traditional methods like vacuum bagging, leading to inadequate conformation and curing issues.

Innovation Solution

The use of expandable tooling with a foamable material that expands within a constrained space to press composite layers against the molding tool, combined with a cutting wire to remove the expanded material after curing, allowing for efficient clamping and removal in complex shape applications.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional vacuum bagging is used to clamp composite layers, then the process is simple, but it is ineffective for complex shapes and does not provide adequate clamping force

Engineering Contradiction:

Improveclamping effectivenessVSAvoidapplicability to complex shapes

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

Instead of applying clamping force from the external side (vacuum bagging), the patent applies clamping force from the internal side by injecting expandable material into the constrained space between the composite layers and mold, reversing the direction of force application to achieve effective clamping for complex shapes

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The expandable material changes its volume parameter by expanding after injection, transforming from a small injected material to a large expanded material that fills the constrained space and provides sufficient clamping force for complex geometric shapes

Inventive Principle:

Principle #35Parameter changes

2Reliability

If expandable material is used to clamp composite layers in constrained space, then effective clamping force is achieved, but the expanded material becomes difficult to remove after curing

Engineering Contradiction:

Improveclamping forceVSAvoidremoval of expanded material

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The cutting wire divides the expanded material into separate segments or pieces, transforming it from a single difficult-to-remove mass into multiple smaller pieces that can be easily extracted from the constrained space after curing

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent replaces mechanical removal methods with thermal cutting by using a heated cutting wire to sever the expanded material, enabling easy separation and removal without complex mechanical extraction systems

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Manufacturing precision

If foamable material is activated to expand within constrained space, then accurate conformation is achieved, but the material occupies significant space after expansion

Engineering Contradiction:

Improveconformation accuracyVSAvoidvolume of expanded material

Core Design Contradiction:

Manufacturing precisionVSVolume of moving object

Solution Approach 1:

The cutting wire cuts the expanded material into multiple smaller pieces, reducing the volume of each individual piece while maintaining the total volume, enabling easier removal from the constrained space after achieving accurate conformation

Inventive Principle:

Principle #1Segmentation

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 method ensures accurate conformation and curing of composite parts in complex shapes by providing effective clamping force from within the constrained space, and facilitates easy removal of the expandable material, enhancing the manufacturing process for composite parts.

Implementation Method 1

a foamable material that is configured to expand into an expanded material within the constrained space

Methodology Applied

Scientific EffectFoam expansion: Foam

Implementation Method 2

heating the cutting wire comprises applying a current through the cutting wire

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Data Source

PatentUS11969960B2Cutting wire for removal of expanded material after curing of a composite part

Publication Date: 2024.04.30 THE BOEING CO

AI summary

Composite fabrication system and associated methods. In one embodiment, a composite fabrication system comprises a molding tool that includes a forming surface at least partially disposed within a constrained space, and a foamable material that expands inside of the constrained space to form an expanded material that presses a layup of one or more composite layers against the molding tool. The composite fabrication system further comprises a curing device configured to cure the layup to form a composite part, and a cutting wire embedded in the constrained space that is heated and configured to cut the expanded material into pieces that are removable from the constrained space.