Mandrel Voids via Thermoplastic Member Contraction

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Solution Overview

Problem

Current methods for forming mandrels with voids to control expansion during curing processes often fail to achieve dimensions within selected tolerances, leading to uneven pressure and distorted composite structures, and are either expensive or time-consuming.

Innovation Solution

A system and method using thermoplastic members inserted through openings in a structure, where the members are supported and surrounded by material that hardens to form a mandrel with controlled voids, allowing for precise formation of voids within the mandrel to manage expansion during curing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If extrusion techniques are used to form voids in mandrels, then the mandrel can be formed with voids, but the dimensions of the voids cannot be formed within selected tolerances

Engineering Contradiction:

Improvevoid dimensionsVSAvoidvoid formation process

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent uses an intermediary material (support material) that is injected into the mold cavity around the mandrel. This support material serves as a mediator to form voids with precise dimensions by displacing the mandrel material in a controlled manner, achieving tolerance levels that extrusion techniques cannot provide.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention changes the parameters of the forming process by using injectable support material with specific rheological properties that allow it to be injected under controlled pressure and temperature conditions. This enables precise control over void dimensions through parameter adjustment rather than relying on extrusion geometry.

Inventive Principle:

Principle #35Parameter changes

2Manufacturing precision

If molding techniques are used to form voids in mandrels, then the mandrel can be formed with voids, but the extraction of the die causes inconsistencies and is more difficult

Engineering Contradiction:

Improvevoid consistencyVSAvoiddie extraction process

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

Instead of extracting a complex die from the molded mandrel, the invention extracts only the necessary support material after curing. The support material is removed through simple extraction channels, leaving clean voids without the inconsistencies caused by die extraction. This reverses the traditional approach by taking out the temporary support rather than the final product.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The support material is injected and positioned in advance before the final mandrel material is cured. This preliminary action allows the void geometry to be established beforehand, ensuring consistency without requiring complex die extraction operations afterward.

Inventive Principle:

Principle #10Preliminary action

3Manufacturing precision

If current void formation methods are used, then mandrels can be formed with voids, but the process is more expensive and time-consuming

Engineering Contradiction:

Improvevoid dimensionsVSAvoidmandrel production rate

Core Design Contradiction:

Manufacturing precisionVSProductivity

Solution Approach 1:

The support material injection and mandrel material curing occur as continuous operations in sequence without interruption. The support material remains in place during curing, providing continuous support and defining void geometry throughout the process, eliminating the need for separate void formation steps and accelerating production.

Inventive Principle:

Principle #20Continuity of useful action

Solution Approach 2:

The invention merges the support structure formation and mandrel formation into a single integrated process. The support material and mandrel material are injected and cured together in one operation, combining multiple steps into one continuous process that reduces both time and cost while maintaining precision.

Inventive Principle:

Principle #5Merging (Combining)

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 method enables the formation of mandrels with voids that ensure even pressure application during curing, maintaining desired shape and tolerances, reducing inconsistencies and costs associated with existing techniques.

Implementation Method 1

Heat may be applied to the number of members such that each of the number of members reduces in size

Methodology Applied

Scientific EffectThermal contraction: Thermal Contraction

Data Source

PatentUS10596733B1Apparatus and system for creating mandrels with voids for expansion control during curing

Publication Date: 2020.03.24 THE BOEING CO

AI summary

A method and apparatus for forming a tool is provided. A number of members comprised of a thermoplastic material is positioned within a hollow portion of a structure. The tool is formed within the hollow portion of the structure with the number of members positioned within the hollow portion of the structure. Heat is applied within a selected range to the number of members to reduce a size of each of the number of members. The number of members is removed from the tool such that the tool is left with a number of voids.