Fiber Preform Positioning via Control Rods in Resin Transfer Moulding
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Solution Overview
Problem
The resin transfer moulding process for forming fibre reinforced composite structures faces challenges such as high tooling costs, dimensional accuracy issues, time constraints for resin infusion, potential tool damage, and difficulty in achieving accurate positioning and thickness control, especially for complex and large components.
Innovation Solution
The use of a hard base tool, a flexible bagging blanket, and rigid control rods to maintain the relative disposition of fibre preforms during resin injection, eliminating the need for complex mandrel systems and ensuring accurate positioning and thickness control through pre-drilled apertures and threaded rods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If two-part hard tooling is used for resin transfer moulding, then dimensional accuracy and positioning of components is improved, but tooling costs and device complexity increase significantly
Solution Approach 1:
The patent extracts the positioning function from the complex two-part hard tooling system and implements it through simple定位 features on the base tool combined with rigid control rods. The control rods maintain preform disposition without requiring complex matched tooling, thereby reducing device complexity while preserving manufacturing precision.
Solution Approach 2:
Instead of using complex hard tooling on both faces to control positioning, the patent inverts the approach by using a simple base tool with定位 features and flexible bagging blanket on the other side, supplemented by rigid control rods. This inversion reduces tooling complexity while maintaining dimensional accuracy.
2Manufacturing precision
If resin is injected edgewise into fibrous preforms through hard tooling, then complete wet out is achieved, but injection time may exceed usable resin injection time
Solution Approach 1:
The patent introduces a flexible bagging blanket as an intermediary that applies uniform pressure during resin injection. This mediator facilitates faster and more complete resin infusion through the preforms compared to hard tooling, reducing injection time while ensuring complete wet out.
3Manufacturing precision
If high injection pressure is used to achieve complete impregnation, then resin infusion is improved, but forces on tooling edges increase leading to potential damage
Solution Approach 1:
The patent uses a flexible bagging blanket instead of rigid hard tooling on the upper side. This flexible film distributes injection pressures uniformly across the preform surface, preventing concentration of forces at tooling edges and eliminating the risk of tooling damage while maintaining impregnation quality.
4Manufacturing precision
If complex mandrel systems are used to maintain preform positioning, then relative disposition accuracy is improved, but device complexity and manufacturing costs increase
Solution Approach 1:
The patent extracts the essential positioning function from complex mandrel systems and implements it through simple定位 features on the base tool combined with rigid control rods. This extraction maintains positioning accuracy while dramatically reducing device complexity and manufacturing costs.
Solution Approach 2:
The patent replaces expensive, complex mandrel systems with simpler, cheaper positioning features and control rods. These simpler components achieve the same positioning function at lower cost and complexity, aligning with the principle of using cheaper objects when they can perform the required function.
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, improves dimensional accuracy, and allows for more complex components to be formed while maintaining structural integrity and reducing the risk of tool damage, enabling efficient resin infusion and curing within an autoclave.
Implementation Method 1
Liquid resin is then injected into the mould cavity under pressure with the intention of fully impregnating the preforms
Implementation Method 2
a flexible bagging blanket for overlying the lay-up region and cooperating with the tool faces to form a sealed enclosure which encloses the first and second reinforcing fibre preforms
Implementation Method 3
at least one rigid control rod inserted in a bore so as to pass at least partially through the first and second reinforcing fibre performs to maintain the relative disposition of said preforms during the liquid resin injection
Implementation Method 4
injecting a liquid resin into the fibrous preforms and curing the resin to form the composite structure
Data Source
AI summary
A method and apparatus for forming a fiber reinforced composite structure comprising at least two components, a hard base tool presenting a first tool face, a second tooling element presenting a second tool face to locate the second component against the first component. Components are of a dry fibrous form and are to be injected with a liquid resin. A flexible bagging blanket forms with the tools a sealed enclosure into which the resin is injected to form the structure by resin transfer infusion. To maintain the relative dispositions of the components without the need for elaborate mandrel plates, control rods are inserted at least partially through the two components to act as fasteners and to maintain the relative disposition of the components during resin injection. After injection the assembly is cured and the control rods may remain in situ or be removed from the structure.