Composite Preform Control Rods for Accurate Resin Transfer Molding

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Solution Overview

Problem

The resin transfer molding process for forming fiber reinforced composite structures faces challenges such as high costs for hard tooling, dimensional accuracy issues, time constraints for resin infusion, potential tool damage, and difficulties in achieving accurate thickness and positioning of complex components.

Innovation Solution

The use of a hard base tool with a flexible bagging blanket and rigid control rods to maintain the relative disposition of reinforcing fiber preforms during resin injection, eliminating the need for mandrels and improving infusion accuracy and control.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If resin transfer molding process is used with hard tooling on both faces, then dimensional accuracy is improved, but manufacturing cost increases significantly

Engineering Contradiction:
Improvedimensional accuracyVSAvoidmanufacturing cost
Core Design Contradiction:
Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The invention extracts and removes one of the hard tooling faces from the molding system, retaining only a single hard base tool while replacing the opposing hard tool with a flexible bagging blanket. This elimination of unnecessary hard tooling reduces manufacturing cost while maintaining adequate dimensional accuracy through the control rod mechanism.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The invention introduces rigid control rods as intermediary elements that pass through the preform and engage with the flexible bagging blanket to maintain preform position and thickness. These control rods act as mediators that enable accurate thickness control without requiring a hard opposing tool, thus reducing cost while preserving dimensional accuracy.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Manufacturing precision

If resin transfer molding with hard tooling is used, then preform positioning accuracy is improved, but tool damage risk increases due to high forces

Engineering Contradiction:
Improvepreform positioning accuracyVSAvoidtool damage
Core Design Contradiction:
Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The invention replaces the rigid hard tooling on the opposing face with a flexible bagging blanket that can deform and accommodate the preform without transmitting high closing forces to hard tool surfaces. This flexible element maintains preform positioning through the control rod mechanism while eliminating the risk of tool damage from high forces.

Inventive Principle:
Principle #30Flexible shells and thin films

3Manufacturing precision

If resin transfer molding with hard tooling is used, then thickness control is improved, but manufacturing time increases due to complete infusion requirement

Engineering Contradiction:
Improvethickness controlVSAvoidmanufacturing time
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

The invention uses rigid control rods that physically copy or replicate the desired preform thickness and positioning geometry. These control rods serve as physical templates that define the exact thickness and position of the preform, enabling accurate replication without requiring time-consuming complete infusion processes or complex hard tooling setups.

Inventive Principle:
Principle #26Copying

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 costs, enhances dimensional accuracy, and allows for the formation of larger and more complex components with improved thickness control and positioning, while minimizing tool damage and infusion time.

Implementation Method 1

rigid control rods to maintain the relative disposition of reinforcing fiber preforms during resin injection

Methodology Applied
Scientific EffectMechanical constraint: Mechanical Force

Implementation Method 2

flexible bagging blanket and cooperating with the tool faces to form a sealed enclosure which encloses the first and second reinforcing fiber preforms

Methodology Applied
Scientific EffectSealing: Physical Containment

Implementation Method 3

injecting a liquid resin into the fibrous preforms

Methodology Applied
Scientific EffectResin infusion: Capillary Action

Implementation Method 4

injection of liquid resin may be carried out with or without vacuum assistance

Methodology Applied
Scientific EffectPressure-driven flow: Pressure Increase

Implementation Method 5

curing the resin to form the composite structure

Methodology Applied
Scientific EffectCuring: Photopolymerisation

Data Source

PatentEP4098891A1Apparatus and method for forming fiber reinforced composite structures
Publication Date: 2022.12.07 SHORT BROTHERS PLC
  • EP4098891A1 patent drawingFigure 1
  • EP4098891A1 patent drawingFigure 2
  • EP4098891A1 patent drawingFigure 3~5A

AI summary

A composite assembly includes at least a first composite preform, a second composite preform, and a control rod. The control rod has a shaft defining an axis, wherein the shaft is disposable within an aperture in the composite assembly, and a plurality of threads disposed on at least a portion of the shaft. The threads define a thread pitch that encompasses more than one individual fiber layer forming at least one of the first composite layer and the second composite layer.