Curved Composite Stringer Forming via Rotatable Pallet
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Solution Overview
Problem
Aircraft stringer manufacturing faces challenges in forming curved composite charges due to the need for multiple tools and stages, which increases costs and can result in wrinkles during bending operations.
Innovation Solution
A method and device that integrate in-plane and out-of-plane bending capabilities into the stringer shaping process, using a rotatable pallet system with a bendable die to form curved composite charges, reducing the risk of wrinkles and consolidating multiple processing stages into one operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If conventional two-stage shaping and bending is used, then stringer bends can be formed, but wrinkles are caused and manufacturing complexity increases
Solution Approach 1:
The patent combines the shaping and bending operations into a single integrated forming process. The forming tool includes both a die for shaping the hat portion and a cavity for receiving the bent stringer, allowing both operations to be performed simultaneously without transferring the stringer to another tool, thereby eliminating wrinkles caused by separate bending operations
Solution Approach 2:
The patent performs the bending operation during the initial shaping process rather than as a subsequent step. The stringer is bent into its final configuration while still in the forming tool, before the shaping is completed, ensuring that the bending occurs under controlled conditions that prevent wrinkle formation
2Shape
If dedicated forming tools are created for each stringer type, then specific shapes can be formed, but manufacturing costs and device complexity increase
Solution Approach 1:
The forming tool is designed with a die and cavity system that can accommodate multiple stringer types and configurations. The die can be positioned at different locations within the cavity, and the cavity can receive stringers with various bends and turns, allowing a single tool to produce different stringer shapes without requiring dedicated tools for each type
Solution Approach 2:
The forming tool incorporates adjustable components, including a die that can be positioned at different locations within the cavity and a stringer support that can be adjusted to accommodate different stringer configurations. This dynamic adjustability allows the same tool to produce various stringer shapes and configurations
3Shape
If multiple processing stages are used, then complex shapes can be formed, but process time and productivity decrease
Solution Approach 1:
The patent merges multiple processing stages into a single forming operation. The shaping of the hat portion and the bending of the stringer are performed simultaneously in one operation, eliminating the need to transfer the stringer between tools and reducing the total number of process steps, thereby increasing productivity
Data Source
Figure 1A~1B
Figure 1C~1E
Figure 1F~1G
AI summary
Described are methods and systems for manufacturing curved composite stringers. Such composite stringers may have in-plane and/or out-of-plane bends, which are formed while shaping composite charges. Specifically, a composite charge (130) is shaped using a pallet (310), comprising a plurality of independent pallet portions (319), rotatably coupled to each other. A hat portion (131) is formed when a part of this charge is conformed to a cavity (318) in the pallet. The pallet portions (319) are rotated relative to each other while forming the hat portion (131) and/or when the hat portion (131) already conforms to the cavity (318). In some examples, the die (320) is bent together with the charge (130), when the pallet portions (319) are rotated. This rotation produces one or more of in-plane and/or out-of-plane bends. In some examples, flange portions (136) of the composite charge (130) are positioned in a temporary orientation, e.g., to enable bending of the charge and reduce wrinkles.