Stitched Fiber Preform With Vacuum Compression for Needle Access
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Solution Overview
Problem
Existing sewing machines have limitations on the thickness of material that can be sewn due to the distance between the needle and the work surface, leading to issues with maintaining the shape of fiber preforms during infusion and encapsulation in composite part manufacturing, resulting in thicker preforms post-processing.
Innovation Solution
A sewing system comprising a sewing machine, vacuum pump, and polymer bag that reduces pressure inside the bag to compress the fiber preform, allowing stitches to be made through the compressed preform, maintaining its shape and facilitating precise filament placement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If the preform is stitched before infusion and encapsulation without compression, then the preform shape can be maintained during sewing, but the preform thickness remains larger than the final composite part thickness
Solution Approach 1:
The preform is compressed within the vacuum bag before stitching begins. The vacuum pump creates negative pressure that compresses the preform to its final thickness, and then stitching is performed on the already-compressed preform. This preliminary compression action ensures the preform maintains the correct thickness throughout the stitching process and in the final composite part.
Solution Approach 2:
A vacuum bag system is used to apply pneumatic pressure (negative pressure) to compress the preform. The vacuum pump creates a pressure differential that uniformly compresses the preform to the desired thickness before and during the stitching operation, resolving the contradiction between maintaining shape and reducing thickness.
2Ease of manufacture
If a sewing machine is used to stitch thick uncompressed preform material, then the stitching process can be performed, but the needle distance limitation prevents effective stitching through the entire thickness
Solution Approach 1:
The preform is compressed to its final thickness before the stitching process begins. This preliminary compression reduces the material thickness to a level that the sewing machine needle can effectively penetrate, allowing the stitching process to be completed successfully through the entire thickness of the preform.
Solution Approach 2:
The physical state of the preform is changed from uncompressed to compressed by applying vacuum pressure. This parameter change (compression) reduces the thickness of the material, making it suitable for stitching with a standard sewing machine needle while maintaining the integrity and shape of the preform.
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
The method ensures the fiber preform maintains its compressed shape during stitching, reducing stitch length variability and enhancing the strength and integrity of the final composite part by minimizing filament movement and defects.
Implementation Method 1
a polymer bag configured to hold a fiber preform and to connect to the vacuum pump so that gas inside the polymer bag is removable by the vacuum pump to thereby reduce a pressure inside the polymer bag to less than an ambient pressure
Implementation Method 2
compress the fiber preform to a compressed thickness thereby forming a compressed fiber preform
Data Source
AI summary
A sewing system can include a sewing machine; a vacuum pump; and a polymer bag configured to hold a fiber preform and to connect to the vacuum pump so that gas inside the polymer bag is removable by the vacuum pump to thereby reduce a pressure inside the polymer bag to less than an ambient pressure of an outside of the polymer bag, and to compress the fiber preform to a compressed thickness thereby forming a compressed fiber preform, so that a pattern of stitches of a filament are stitchable through the polymer bag and the compressed fiber preform by the sewing machine while the pressure inside the polymer bag is less than the ambient pressure.