Contoured Composite Stiffener Forming with Flexible Tooling
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Solution Overview
Problem
The fabrication of composite blade stiffeners using multiple separate charges is labor-intensive and time-consuming, especially when forming highly contoured stringers, as it requires complex tooling and is prone to ply wrinkling, limiting the efficiency and cost-effectiveness of the process.
Innovation Solution
A method and apparatus using a single composite charge with simplified tooling, featuring a flexible elongate punch and die, along with flexible plates and shims, to form contoured blade stringers with reduced ply wrinkling and misalignment, allowing for localized contouring through ply pad-ups and pad-downs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If multiple separate composite charges are used to form blade stringers, then the desired stringer configuration can be achieved, but the process becomes labor-intensive and time-consuming
Solution Approach 1:
The patent merges multiple separate composite charges into a single integrated charge that forms the complete blade stringer in one operation. This eliminates the need to manually assemble multiple stringer members, significantly reducing labor intensity and manufacturing time while maintaining the desired complex stringer configuration
2Shape
If conventional tooling is used to form highly contoured stringers, then the stringers can be shaped, but ply wrinkling occurs during compression
Solution Approach 1:
The patent employs a flexible die that can dynamically adapt its shape during the forming process. The die flexes to accommodate the contoured configuration of the blade stringer while maintaining uniform pressure distribution, preventing ply wrinkling and ensuring high manufacturing precision even for highly contoured stringers
Solution Approach 2:
The patent changes the physical state parameters of the composite charge by controlling temperature and pressure conditions during forming. The charge is heated to a forming temperature to increase its pliability, allowing it to conform to the contoured die shape without wrinkling, then cooled to set the final shape
3Manufacturing precision
If hand layup techniques are used to reduce ply wrinkling, then surface quality improves, but labor intensity and cost increase
Solution Approach 1:
The patent employs a self-service forming mechanism where the flexible die automatically maintains proper pressure distribution and prevents ply wrinkling during the forming process. The die's flexibility allows it to self-adjust to the contoured shape, eliminating the need for manual ply-by-ply placement while achieving the same surface quality as hand layup techniques
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 tooling costs and manufacturing flow times by forming a single composite charge into a desired configuration, enabling efficient and cost-effective production of contoured blade stiffeners with improved surface quality and reduced labor intensity.
Implementation Method 1
forming a generally flat charge into a hat shape having a pair of flanges by using a punch to press the charge into a cavity in a die
Implementation Method 2
first and second flexible plates respectively backing the first and second plies, and a press coupled with the blades for forming the punch and the die into a desired contour
Data Source
Figure 1~3
Figure 4
Figure 5~6A
AI summary
Tooling apparatus (68) for forming a composite charge (55) into a contoured composite blade stringer (50) includes an elongate punch and an elongate die flexible along their lengths. The charge is press formed by using the punch to drive the charge into the die. The punch and the die are mounted between a pair of flexible plates. A press coupled with the plates contours the charge by bending the plates into a desired contour.