Articulated Forming Caul for Composite Vacuum Bagging
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Solution Overview
Problem
Current methods for forming composite parts, especially thick and complex geometries, face challenges in controlling thermal and mechanical loads, leading to difficulties in achieving desired shapes and fiber arrangements, and are often costly and time-consuming, with high equipment costs and risks of premature curing.
Innovation Solution
A vacuum bag system with an articulated forming caul (AFC) and a rigid single-sided mold (RSSM) is used, where the AFC has jointed forming elements with independent heating and mechanical joints, allowing intimate contact with the blank and movement to match the RSSM, while a two-enclosure vacuum bagging system ensures registration and controlled deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If automated placement machines are used for layup, then placement accuracy and automation are improved, but equipment costs and forming time for complex geometries increase substantially
Solution Approach 1:
The patent uses a rigid single-sided mold (RSSM) as a reusable master pattern that defines the target geometry. The AFC copies this geometry by articulating to match the RSSM surface, eliminating the need for complex automated placement equipment while maintaining geometric fidelity through the mold as a template
Solution Approach 2:
The system changes the physical state of the composite blank by heating it to above the glass transition temperature of the matrix, making it deformable. This allows simple vacuum bagging equipment to achieve complex geometries that would otherwise require sophisticated automated placement systems
2Manufacturing precision
If heat is applied during automated layup to ensure consolidation, then consolidation quality is improved, but risk of premature curing increases
Solution Approach 1:
The composite blank is pre-consolidated at room temperature through vacuum bagging before any heating occurs. This preliminary consolidation removes air and establishes good ply-to-ply contact, allowing subsequent heating to be applied safely without risk of premature curing, as the material is already in its final consolidated state
Solution Approach 2:
The process separates consolidation and heating into distinct sequential stages: first consolidation at room temperature, then heating for deformation. This segmentation eliminates the risk of premature curing that would occur if heat and consolidation were applied simultaneously during layup
3Ease of manufacture
If simple vacuum bagging is used without articulated forming caul, then equipment cost is reduced, but control over thermal and mechanical loads during forming is insufficient
Solution Approach 1:
The AFC uses mechanical joints (hinges, sliders) that allow forming elements to dynamically articulate and adapt their position as the blank deforms. This dynamic adjustment maintains intimate contact between the blank and forming surfaces throughout the deformation process, providing precise control over mechanical loads while keeping the system mechanically simple
Solution Approach 2:
The system applies localized heating through heaters attached to individual AFC forming elements, allowing different regions of the blank to receive different thermal loads. This local quality control enables precise management of thermal and mechanical conditions in specific areas without affecting the entire part
4Adaptability or versatility
If thick composite parts with complex geometry are formed, then product capability is improved, but difficulty in controlling fiber arrangement and achieving desired shape increases
Solution Approach 1:
Heating the thick composite blank above the glass transition temperature of the matrix fundamentally changes the material's rheological properties, making it deformable and allowing fibers to reorient. This parameter change enables complex geometries and precise fiber arrangement control in thick sections that would be impossible to form in the rigid, glassy state
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 method enables high-degree deformation and complexity in forming thick composite parts with minimal tooling and equipment investment, providing improved control over fiber and matrix movements, reducing defects, and allowing for efficient production of complex geometries with precise control over thermal and mechanical loads.
Implementation Method 1
a first evacuation system; an outer bag system (10b), and an enclosure (16a,b) for effecting the forming
Implementation Method 2
each forming element having a respective, independently controlled, heater integrated with, or coupled to the forming element
Implementation Method 3
the elements of the AFC are receivable within the blank enclosure, or bonded to an interior or exterior of the first membrane... bringing the blank and the facets into uniform thermal contact resistance, and mechanical contact
Data Source
AI summary
A vacuum bag system (VBS) for forming pre-consolidated composite blanks has a blank enclosure for sealing around a periphery of the blank, while leaving a second side of the blank exposed, an articulated forming caul (AFC) with at least two facets, each facet effectively jointedly coupled to an adjacent facet, and having a respective, independently controlled, heater integrated with, or coupled to the facet. The VBS further has a forming enclosure for sealing around a periphery of a tool. The blank enclosure brings the blank and the facets into uniform thermal contact resistance and mechanical contact; and permits the articulated AFC to distribute thermal and mechanical load across the blank during forming, even as the facets move to align to faces of the mold.