Independent Vacuum Pallets for Composite Stringer Layup
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Solution Overview
Problem
Challenges in maintaining reduced pressure during composite stringer manufacturing due to vacuum leaks and the need for independent vacuum control on movable pallets in forming tools.
Innovation Solution
A stringer forming system with independently movable pallets, each with a primary vacuum zone connected to a separate vacuum port, allowing selective application of reduced pressure only to covered pallets, while exposed pallets remain at ambient pressure, reducing leakage and improving vacuum efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a reduced pressure is applied to various features on a forming tool surface, then composite layup support is improved, but vacuum leakage increases when pallets are exposed or moving
Solution Approach 1:
The forming tool is divided into multiple independently controllable pallets, each with its own vacuum zones and ports. This segmentation allows selective application of vacuum only to pallets that are currently in use (covered with composite layup), while exposed or transitioning pallets remain at atmospheric pressure, thereby eliminating vacuum leakage from exposed areas.
Solution Approach 2:
Different regions of the forming tool (individual pallets) are given different pressure conditions based on their operational state. Pallets actively supporting composite layup are maintained at reduced pressure, while pallets that are exposed or being repositioned are kept at atmospheric pressure. This local differentiation optimizes vacuum efficiency by applying pressure control only where needed.
2Adaptability or versatility
If pallets are moved to adjust cavity size, then adaptability is improved, but maintaining fluid connections to vacuum sources becomes challenging
Solution Approach 1:
The system transitions from static vacuum connections to dynamic, selectively activated connections. Each pallet can be independently connected to or disconnected from vacuum sources based on its position and operational requirements, allowing the system to adapt to moving pallets while maintaining vacuum integrity.
Solution Approach 2:
Vacuum connections are established or disconnected in advance based on the operational sequence. Pallets are pre-configured with their vacuum port states before movement or layup operations begin, ensuring that vacuum is applied only when and where needed, simplifying control during dynamic operations.
3Reliability
If reduced pressure is applied to all pallets, then composite layup support is improved, but vacuum leakage through exposed pallets increases
Solution Approach 1:
The vacuum system is segmented into independent zones corresponding to individual pallets. This allows the operator to activate vacuum only on pallets that are currently supporting composite layup, while leaving other pallets at atmospheric pressure. The segmentation eliminates the need to maintain vacuum across the entire forming tool surface, thereby improving vacuum efficiency and reducing energy consumption.
Solution Approach 2:
Instead of applying vacuum to the entire forming tool surface (excessive action), the system applies vacuum only to the specific pallets and zones where composite layup is present (partial action). This optimized approach maintains adequate support for the composite material while avoiding the energy waste and leakage issues associated with vacuuming the entire surface.
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
Enhances vacuum integrity by minimizing leaks, enabling lower pressure levels and efficient composite layup support, even with moving pallets, thus improving the manufacturing process.
Implementation Method 1
Each pallet comprises a processing surface and a primary vacuum zone, on the processing surface, fluidly connected to a primary vacuum port. The primary vacuum port of each pallet is independently controlled, allowing selective application of reduced pressure only to covered pallets
Data Source
AI summary
Described herein are methods and systems for manufacturing composite stringers using independently movable pallets with independent vacuum controls. Specifically, a stringer forming system comprises a base plate and a plurality of sets of pallets (e.g., two or more sets of pallets), slidably coupled to the base plate and forming an adjustable cavity. Each pallet comprises a primary vacuum zone, fluidly connected to a separate vacuum port. The system allows for independent application of a reduced pressure to the primary vacuum zone of each pallet. For example, a reduced pressure is applied only to pallets that are already covered with a composite layup and to pallets that are being covered. Any pallets that are exposed are kept at an ambient pressure and decoupled from a vacuum source, thereby reducing the vacuum leakage through the overall system. As the composite layup is being formed over new pallets, these new pallets are subjected to the reduced pressure.