Two-Piece Mandrel for CMC Components with Constant Cross-Section
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Solution Overview
Problem
Existing methods for forming blade outer air seals from ceramic matrix composite fiber layers using mandrels often require tapers to facilitate mandrel removal, which complicates the component design and manufacturing process.
Innovation Solution
A two-piece mandrel with opposing radial wedges and dovetail surfaces is used, allowing for a constant cross-section and easy removal without the need for tapers, while self-centering locking pins ensure precise control over the component's wall thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a traditional mandrel is used for forming CMC components, then the mandrel can be removed from the component, but tapers are required on the mandrel which complicates the component design and manufacturing process
Solution Approach 1:
The mandrel is divided into two separate halves that can be positioned on opposite sides of the component. Each half independently forms a portion of the component's cross-section, allowing both halves to be removed separately without requiring tapered geometry for extraction.
Solution Approach 2:
Instead of removing the mandrel axially from one end (traditional approach requiring tapers), the two-piece mandrel allows removal from opposite directions simultaneously, utilizing the dimensional space around the component to enable extraction without geometric modifications.
2Shape
If a traditional mandrel with tapers is used, then mandrel removal is facilitated, but the cross-section of the component cannot be constant and fully enclosed
Solution Approach 1:
By splitting the mandrel into two halves, the system can form a complete constant cross-section around the entire component perimeter, then remove each half independently through opposite ends, achieving both geometric fidelity and extraction ease.
Solution Approach 2:
Instead of designing the mandrel to be removed from one end (requiring tapers that compromise the cross-section), the invention inverts the approach by enabling removal from opposite ends simultaneously, preserving the constant fully enclosed cross-section.
3Manufacturing precision
If locking pins are used to maintain gap between mandrel portions, then precise control over wall thickness is achieved, but the mandrel structure becomes more complex
Solution Approach 1:
Locking pins serve as intermediary elements that physically maintain the predetermined gap between the two mandrel halves. These pins are simple cylindrical elements that can be inserted through aligned holes, providing precise spacing control without requiring complex mechanical linkages or adjustment mechanisms.
Solution Approach 2:
The gap distance between mandrel portions is predetermined by the dimensions of the locking pins themselves. By changing the parameter of pin diameter or length, the wall thickness of the formed component can be precisely controlled without modifying the overall mandrel structure or requiring complex adjustment mechanisms.
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
A mandrel (300) for a molding process that includes a first portion (302) that has a first portion outer surface (306), a first portion inner surface (312), a first portion first end (303), and a first portion second end (305). A thickness (Hi) of the first portion first end (303) is greater than the first portion second end (305). A second portion (304) has a second portion outer surface (310), a second portion inner surface (308), a second portion first end (303), and a second portion second end (305). A thickness (H2) of the second portion first end (303) is smaller than the second portion second end (305). The first portion inner surface (312) engages the second portion inner surface (308) to form a mandrel that has a constant cross-section.