Composite Cell Array Curing With Conductive Tool Blocks

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Solution Overview

Problem

The existing methods for thermal curing of adhesively bonded cell-based arrays face issues with uneven heating due to high thermal mass of tooling blocks, leading to non-uniform adhesive curing, resulting in scrap, increased manufacturing costs, and reduced production yields.

Innovation Solution

A method and apparatus utilizing thermally conductive elements within tool blocks, which are convectively heated by warm air, ensuring uniform heat distribution across the cell array through conduction, reducing the thermal gradient and enhancing curing consistency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If conventional convection heating is used to cure adhesive in cell-based arrays, then the heating process is simple to implement, but the heat distribution is non-uniform due to thermal gradients caused by high thermal mass of tooling blocks

Engineering Contradiction:
Improveease of implementationVSAvoiduniformity of adhesive curing
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

A thermally conductive element (such as a metal rod or pin) is introduced as an intermediary between the convection heat source and the tooling block. This element has higher thermal conductivity than the tooling block, allowing it to efficiently conduct heat from the convection source through the tooling block to the adhesive, thereby achieving uniform heat distribution while maintaining the simplicity of convection heating

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The heating system is modified by adding a thermally conductive element with superior thermal conductivity properties at the critical location where heat transfer occurs. This creates a localized enhancement in heat conduction capability, ensuring that heat is distributed uniformly across the adhesive bondline without requiring complete redesign of the entire heating system

Inventive Principle:
Principle #3Local quality

2Ease of operation

If tooling blocks with high thermal mass are used, then the tooling blocks can be inserted into cells for curing, but they cause uneven heating and slow heating of interior sections

Engineering Contradiction:
Improveability to insert tooling blocks into cellsVSAvoidheating speed of interior sections
Core Design Contradiction:
Ease of operationVSSpeed

Solution Approach 1:

A thermally conductive element is inserted into the tooling block to act as a heat conduit. This element rapidly conducts heat from the convection source through the tooling block to the adhesive in interior sections, overcoming the slow heating problem caused by the high thermal mass of the tooling block while maintaining the operational simplicity of using insertable tooling blocks

Inventive Principle:
Principle #24Intermediary (Mediator)

3Productivity

If conventional curing methods are used, then the process is straightforward, but adhesive curing uniformity does not meet process specifications resulting in scrap and rework

Engineering Contradiction:
Improveproduction yieldVSAvoidadhesive curing uniformity
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The thermally conductive element serves as a mediator that ensures uniform heat distribution to the adhesive, guaranteeing that curing uniformity meets process specifications. This eliminates the need for scrap and rework while maintaining the straightforward nature of the curing process

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The thermal conductivity parameter of the heating system is enhanced by introducing a material with higher thermal conductivity (the thermally conductive element). This parameter change ensures that heat is distributed uniformly across all adhesive bondlines, meeting curing specifications and improving production yield

Inventive Principle:
Principle #35Parameter changes

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 achieves consistent and uniform heating of adhesive bondlines, reducing fabrication and rework costs, increasing production yields, and decreasing cure times while allowing for the use of fewer and less expensive thermocouples and cure ovens.

Implementation Method 1

a thermally conductive element extending substantially through the tool block and having an exposed portion outside of the tool block, the thermally conductive element capable of being convectively heated by a flow of warm air passing over the exposed portion thereof

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

the thermally conductive element capable of being convectively heated by a flow of warm air passing over the exposed portion thereof

Methodology Applied
Scientific EffectConvection: Convection

Data Source

PatentEP2803461B1Thermal curing of cell-based structural arrays
Publication Date: 2023.11.01 THE BOEING CO
  • EP2803461B1 patent drawingFigure 1~2
  • EP2803461B1 patent drawingFigure 3
  • EP2803461B1 patent drawingFigure 4

AI summary

Cells (30) of a composite cell array are cured by placing tool blocks (42) in the cells and inserting thermally conductive elements (44) in each of the tool blocks. The thermally conductive elements are convectively heated by a flow of hot air. The heated conductive elements (44) conduct heat to the tooling blocks, which then conduct heat to the cells to cure the composite and adhesive.