Composite Tube Assembly With Sacrificial Support for Thin-Wall Drawing
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Solution Overview
Problem
The development of lightweight, high-flux heat exchangers for applications such as near-space air breathing flight vehicles poses challenges in manufacturing small diameter, thin-walled tubing due to issues like through-the-wall defects and material contamination.
Innovation Solution
The use of composite tube assemblies comprising a functional tube made of superalloy and a sacrificial tube, where the sacrificial tube is removable by exposure to a corrosive media, addresses the challenges of defect formation and material contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If tube drawing is used to form small diameter, thin-walled tubing, then the tubing can be produced with controlled dimensions, but through-the-wall defects occur and manufacturing complexity increases
Solution Approach 1:
A sacrificial tube is introduced as an intermediary element during the tube drawing process. The sacrificial tube is positioned inside the functional tube and serves as a temporary support structure that prevents wall thinning and defect formation during drawing. After drawing, the sacrificial tube is removed by exposure to corrosive media, leaving a defect-free functional tube.
Solution Approach 2:
The tube formation process is segmented into two independent components: a functional tube and a sacrificial tube. These are drawn separately and then assembled into a composite structure. This segmentation allows each tube to be optimized independently and eliminates the transfer of defects from one continuous drawing operation.
2Ease of manufacture
If conventional lubrication and degreasing practices are used in tube drawing, then the drawing process can proceed smoothly, but carbon or nitrogen contamination of the tube material occurs
Solution Approach 1:
The sacrificial tube acts as a protective intermediary barrier between the tube drawing process and the functional tube material. It prevents direct contact between conventional lubricants/degreasers and the functional tube, thereby eliminating carbon and nitrogen contamination while still allowing the drawing process to proceed with standard practices.
Solution Approach 2:
The harmful elements (carbon and nitrogen from lubrication chemicals) are extracted from the system by using the sacrificial tube as a barrier. The sacrificial tube is subsequently removed along with any accumulated contaminants, leaving the functional tube free from contamination.
3Manufacturing precision
If bench drawing is used to form small diameter, thin-walled tubing, then high-quality tubing can be produced, but production capacity is limited and cost increases
Solution Approach 1:
The patent merges automated coil drawing technology with the sacrificial tube concept to achieve both high productivity and high quality. By combining these approaches, long lengths of tubing can be produced continuously through coil drawing while the sacrificial tube ensures defect-free walls throughout the process.
Solution Approach 2:
The invention enables parameter changes in the drawing process, specifically allowing for higher drawing speeds and longer production lengths that were not feasible with traditional bench drawing. The sacrificial tube provides the necessary support to maintain quality at these new operating parameters.
4Productivity
If coil drawing with tube sinking is used to produce small diameter tubing, then production efficiency can be improved, but through-the-wall defects occur at and away from welds
Solution Approach 1:
The tube is segmented into functional and sacrificial components that are drawn separately and then assembled. This segmentation eliminates the weld-related defects that occur in coil drawing, as the functional tube can be formed without welding or with minimal welding that does not compromise wall integrity.
Solution Approach 2:
The sacrificial tube serves as a mediator during the coil drawing process, providing internal support that prevents wall collapse and defect formation. This is particularly important in coil drawing where the tube undergoes significant deformation and where welds may create stress concentration points.
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 enables the formation of drawn functional tubes with reduced or eliminated through-the-wall defects and minimizes carbon and nitrogen contamination, resulting in high-quality tubing suitable for demanding applications.
Implementation Method 1
the sacrificial tube is removable by exposure to a corrosive media
Implementation Method 2
the first inner surface and the second outer surface are metallurgically bonded to each other
Data Source
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Figure 2B
AI summary
Composite tube assemblies and thin-walled tubing are disclosed. In embodiments, the composite tube assemblies include a functional tube and a sacrificial tube disposed within or around the functional tube. The sacrificial tube may be removed by exposure to a corrosive media, without substantially affecting the functional tube. Methods of forming composite tube assemblies and thin-walled tubing are also described.