Tapered Mandrel Transition Sections for Continuous CMC Braiding
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Solution Overview
Problem
The fabrication of ceramic matrix composite (CMC) articles is time-consuming and wasteful due to substantial set-up times and the need to remove lead-in regions during the braiding or weaving process, leading to ceramic fiber waste.
Innovation Solution
A continuous one-piece mandrel with a pilot lead-in section, article sections, and tapered transition sections is used to facilitate seamless braiding or weaving, reducing waste and enhancing processing efficiency by allowing for the production of multiple CMC articles without mechanical joints.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a traditional mandrel is used for forming CMC articles, then the article can be formed, but substantial set-up time is required and lead-in regions must be removed causing ceramic fiber waste
Solution Approach 1:
The mandrel is divided into distinct sections: a lead-in section for initiating braiding, multiple article sections for forming different CMC articles, and transition sections connecting them. This segmentation allows continuous braiding through multiple articles without stopping, eliminating the need to remove and reposition mandrels between articles, thus reducing both set-up time and ceramic fiber waste.
Solution Approach 2:
Multiple article sections are combined into a single continuous mandrel structure, allowing multiple CMC articles to be formed in one continuous braiding operation. This merging eliminates the need for separate mandrels and set-up operations for each article, improving productivity and reducing waste.
2Productivity
If a continuous one-piece mandrel with multiple article sections is used, then productivity is improved, but the mandrel structure becomes more complex
Solution Approach 1:
The complex mandrel structure is managed through segmentation into standardized sections (lead-in, article, transition). Each section serves a specific function and can be designed independently, making the overall complex structure more manageable and manufacturable despite producing multiple articles simultaneously.
3Manufacturing precision
If lead-in regions are removed from CMC articles, then the articles can be finalized, but ceramic fiber waste increases
Solution Approach 1:
The lead-in sections of multiple articles are merged into a single continuous braiding process. The braiding starts once in the lead-in section and continues through multiple article sections, so the ceramic fibers are fully utilized across all articles rather than being wasted in separate lead-in regions for each article.
Solution Approach 2:
The lead-in section serves as a preliminary region where braiding is initiated and stabilized before the actual article formation begins. By designing this lead-in section as part of a continuous mandrel that serves multiple articles, the preliminary action is performed once rather than repeatedly for each article, reducing waste.
Data Source
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AI summary
A method includes providing a continuous mandrel body (22) disposed along an axis (A). The mandrel body (22) defines, in order along the axis (A) from a first end (22a) thereof, a pilot lead-in section (24), a first article section (26), a tapered transition section (28), and a second article section (30). Beginning at the pilot lead-in section (24), a continuous fabric sleeve (32) is progressively formed on the mandrel body (22) to the first article section (26), to the tapered transition section (28), and then to the second article section (30) to form a fabric-covered mandrel (20). The portions of the continuous fabric sleeve (32) that are on the first article section (26) and the second article section (30) form, respectively, a first article preform (34a) and a second article preform (34b). The fabric-covered mandrel (20) is then divided to separate the article preforms (34a, 34b), followed by densifying the article preforms (34a, 34b) with a ceramic matrix material to thereby form CMC articles.