Expandable Tooling for Composite Cavity Pressure

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Solution Overview

Problem

The existing methods for manufacturing composite parts face challenges in removing internal tooling after curing, as it is either costly and time-consuming to produce removable tooling or leaves the tooling within the structure, increasing the weight and complexity of the cured composite.

Innovation Solution

The use of expandable tooling systems, such as expandable pellets or bladders, that are inserted into the composite workpiece cavity in an unexpanded state and expand during the curing process to apply pressure, allowing for easy removal after curing by shrinking or extraction methods like magnetically attractable beads or pressurized fluids.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Weight of moving object

If removable internal tooling is used, then the weight of the cured composite is reduced by allowing tooling removal, but the manufacturing cost and time increase due to complex tooling production and removal processes

Engineering Contradiction:

Improveweight of cured compositeVSAvoidmanufacturing complexity

Core Design Contradiction:

Weight of moving objectVSEase of manufacture

Solution Approach 1:

The tooling material undergoes a phase change from solid to expanded state through temperature change. The expandable beads are inserted in a compact unexpanded state, then heated to expand and apply curing pressure, and finally cooled to contract for easy removal. This parameter change resolves the contradiction by enabling simple removal without complex mechanisms.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The expandable beads utilize thermal expansion phase transition to change volume and density. In the unexpanded state, they are small and easy to insert. During curing, they expand to provide necessary pressure. After curing, they are cooled to contract for removal. This phase transition eliminates the need for complex removal processes while maintaining lightweight benefits.

Inventive Principle:

Principle #36Phase transitions

2Ease of manufacture

If traditional internal tooling is left in the structure, then the manufacturing process is simplified, but the weight and complexity of the cured composite increase

Engineering Contradiction:

Improvemanufacturing process simplicityVSAvoidweight of cured composite

Core Design Contradiction:

Ease of manufactureVSWeight of moving object

Solution Approach 1:

The tooling material transitions from a static expanded state during curing to a dynamic contracted state for removal. The expandable beads can change their volume and physical state, allowing them to serve as effective internal tooling during curing, then be easily removed after curing by cooling and contracting. This dynamic property enables both manufacturing simplicity and weight reduction.

Inventive Principle:

Principle #15Dynamics

3Manufacturing precision

If custom internal tooling is manufactured for each part, then the curing process can be optimized, but the manufacturing cost and time increase significantly

Engineering Contradiction:

Improvecuring process optimizationVSAvoidmanufacturing efficiency

Core Design Contradiction:

Manufacturing precisionVSProductivity

Solution Approach 1:

The expandable beads serve multiple functions: they act as internal tooling during curing, provide controlled expansion pressure, and enable easy removal after curing. This multi-functionality eliminates the need for custom-designed internal tooling for each part, significantly improving manufacturing efficiency while maintaining curing process optimization.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The expandable beads are inexpensive, simple materials that can be easily inserted and removed. They serve their purpose as internal tooling during the curing process and then can be discarded or reused, eliminating the need for expensive, custom-manufactured internal tooling that would need to be precisely fitted for each part geometry.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

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 reduces the weight of the cured composite by allowing tooling removal, simplifies the manufacturing process, and enables the production of complex shapes without the need for custom internal tooling, while being environmentally friendly and cost-effective.

Implementation Method 1

the unexpanded first element being configured to expand when heated by a predetermined amount; expanding the unexpanded first element by heating the first element by a predetermined amount

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 2

applying a positive pressure to an inner surface of the workpiece assembly forming the cavity by heating the unexpanded first element from a first temperature to a second temperature higher than the first temperature

Methodology Applied

Scientific EffectHeating: Heating

Data Source

PatentUS11046027B2Expandable tooling systems and methods

Publication Date: 2021.06.29 THE BOEING CO

AI summary

Prior to curing a composite workpiece assembly, an expandable element can be inserted into a cavity of the workpiece assembly. The expandable element is configured to expand when a predetermined change is produced in an attribute of the element. The attribute can be a temperature of the element. The element is expanded by producing the predetermined change, and the workpiece assembly is cured while the expanded element is in the cavity, so that the expanded element applies positive pressure to inner surfaces of the cavity during curing. The expanded element can be removed from the cavity after curing. The expanded element can comprise a plurality of expandable pellets.