Composite Tube Manufacturing via Threaded Mechanical Interlock
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Solution Overview
Problem
The manufacturing of composite tubes with annular outer and inner layers of different alloys faces challenges such as oxidation and separation during hot working, especially when the alloys are difficult to weld, like iron chromium aluminum (FeCrAl) alloys.
Innovation Solution
A method involving an annular base component with a central through-hole and externally threaded section, and an annular outer component with an internally threaded section, which are mechanically interlocked before hot working to form a metallic bond and prevent oxygen ingress, allowing for the formation of a composite tube with a helical interface that enhances load distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If welding is used to join annular inner and outer layers before hot working, then bonding strength is improved, but the method becomes unsuitable for difficult-to-weld alloys such as FeCrAl alloys
Solution Approach 1:
The patent replaces the welding process (thermal/chemical joining) with a mechanical interlocking system using threaded sections. The externally threaded section of the base component engages with the internally threaded section of the outer component, creating a mechanical connection that eliminates the need for welding difficult-to-weld alloys while maintaining bonding strength during hot working.
2Ease of manufacture
If annular inner and outer layers are placed in contact during hot working, then manufacturing simplicity is improved, but oxygen ingress causes oxidation and prevents metal bonding
Solution Approach 1:
The patent applies preliminary action by creating a mechanical interlock through threaded engagement before the hot working process begins. This pre-established mechanical connection maintains intimate contact between the inner and outer layers throughout subsequent processing, preventing oxygen ingress and oxidation without requiring complex sealing arrangements during hot working.
Solution Approach 2:
The patent segments the bonding interface into multiple threaded contact points along the axial length of the engagement. This segmentation creates numerous small contact areas that collectively provide effective oxygen barrier while allowing for thermal expansion and stress distribution during hot working.
3Ease of manufacture
If mechanical interlocking is used instead of welding, then ease of manufacture is improved, but bonding strength during hot working may be insufficient
Solution Approach 1:
The patent merges two joining mechanisms: mechanical interlocking through threaded engagement and metallurgical bonding through hot working. The threaded sections provide initial mechanical strength and maintain contact during heating, while the subsequent hot working process creates metallurgical bonds between the layers, combining both mechanical and chemical bonding benefits.
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 method effectively prevents oxidation and separation during hot working, forming a strong metallic bond and increasing the interface area for improved load distribution, enabling composite tubes to withstand higher loads and be manufactured without welding, even with alloys that are difficult to join.
Implementation Method 1
forming a mechanical interlock between the threaded sections
Implementation Method 2
a metallic bond is formed between the threaded sections of the outer component and the base component
Data Source
Figure 1~3
Figure 4
Figure 5a~6
AI summary
A method for manufacturing a composite tube having at least one double-layered portion with an annular outer layer of a first alloy and an annular inner layer of a second alloy, comprising : - providing a base component (301) of the second alloy, having a central through-hole and an externally threaded section (302), - providing an outer component (401) of the first alloy, having an internally threaded section (402) configured to engage with the externally threaded section, - forming a tubular work piece by mounting the outer component around the base component such that the internally threaded section is in engagement with the externally threaded section, - hot working the work piece so that a metallic bond is formed between the threaded sections while the mechanical interlock is maintained, and so that the work piece is elongated and its outer diameter is reduced, thus forming a composite tube.