Tube-End Mechanical Attachment With Conical Ring Preload
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Solution Overview
Problem
Existing fixing devices at the ends of composite material tubes, such as those used in aeronautical structures, are difficult to assemble and disassemble, and they do not facilitate repair, reuse, or recycling. Additionally, bonded assemblies require strict implementation for reproducibility and can be destructive or introduce uncertainty in mechanical strength.
Innovation Solution
A fixing device comprising three parts assembled at the end of a tube: a conical insert, an inner ring with a truncated cone-shaped recess, and an external ring. The conical insert is fitted into the inner ring, which is then inserted into the tube, and the external ring is placed around the tube to secure the assembly with a radial thrust that creates a preload.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If threaded sleeves are used to mechanically fix the tube, then strong anchoring is achieved, but the device becomes difficult to assemble and disassemble
Solution Approach 1:
The fixing device is divided into three separate parts: an external ring, an internal ring, and a conical insert. This segmentation allows each component to be independently manufactured and assembled, simplifying the overall assembly process while maintaining strong anchoring capability through the coordinated interaction of these modular components.
Solution Approach 2:
Instead of threading into the tube end directly, the invention inverts the approach by using a conical insert that expands the internal ring radially outward against the tube's inner wall. This inversion of the fastening mechanism from axial threading to radial expansion enables easy assembly and disassembly while preserving strong mechanical anchoring.
2Strength
If bonded assemblies are used to fix the tube, then strong mechanical connection is achieved, but repair and recycling become difficult
Solution Approach 1:
The fixing device is divided into three separate parts: an external ring, an internal ring, and a conical insert. This segmentation allows each component to be independently manufactured and assembled, simplifying the overall assembly process while maintaining strong anchoring capability through the coordinated interaction of these modular components.
Solution Approach 2:
The invention replaces the chemical bonding system with a purely mechanical system based on radial expansion and friction. The conical insert expands the internal ring radially against the tube wall, creating a mechanical anchor that can be assembled and disassembled without chemical adhesives, thereby enabling repair and recycling.
3Reliability
If bonded assemblies are used, then reproducible strength is achieved, but implementation requires extremely strict monitoring
Solution Approach 1:
The invention replaces the chemical bonding system with a purely mechanical system based on radial expansion and friction. The conical insert expands the internal ring radially against the tube wall, creating a mechanical anchor that can be assembled and disassembled without chemical adhesives, thereby enabling repair and recycling.
Solution Approach 2:
The conical insert automatically generates the required radial expansion force when inserted into the internal ring, creating a self-adjusting mechanical connection. This self-service mechanism eliminates the need for external monitoring and control systems, simplifying implementation while ensuring reproducible anchoring strength.
4Strength
If mechanical fastening devices are used, then strong anchoring is achieved, but the structure becomes more complex
Solution Approach 1:
The fixing device is divided into three separate parts: an external ring, an internal ring, and a conical insert. This segmentation allows each component to be independently manufactured and assembled, simplifying the overall assembly process while maintaining strong anchoring capability through the coordinated interaction of these modular components.
Solution Approach 2:
The conical insert is placed inside the internal ring, which itself is inserted into the tube. This nested arrangement of components (insert within ring within tube) creates a compact structure that achieves strong anchoring without adding significant external complexity or increasing the overall footprint of the fixing device.
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 fixing device allows for simple assembly and disassembly, providing strong and reproducible mechanical anchoring while facilitating potential reuse and recycling. The elastic deformation of the inner ring during assembly ensures a secure connection without the need for glues, thus reducing costs and implementation complexities.
Implementation Method 1
The elastic deformation of the inner ring during assembly ensures a secure connection
Data Source
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AI summary
Attachment device (10, 100) obtained by joining three components (12, 14 or 114, 18 or 118) to the end of a tube (16), comprising: - a conical insert (14, 114) in the form of a truncated cone the diameter of which narrows in the direction of the end of the tube, the conical insert (14, 114) having a receiving element (56), - an internal ring (12) which is provided with a recess (52) in the form of a truncated cone the diameter of which narrows in the direction of the interior of the tube and the angle of which is equal to the angle of the truncated cone of the conical insert, the external wall of the internal ring being cylindrical with a diameter substantially equal to the internal diameter of the tube (16), the insert being located in the recess of the internal ring. According to the main features of the invention, the attachment device comprises an external ring (18, 118) comprising a cylindrical portion the internal diameter of which is substantially equal to the external diameter of the tube, the internal wall of the cylindrical portion of the external ring being intended to come into contact with the cylindrical external wall of the tube (16), the external ring comprising a shoulder (28, 128) which partially closes an end of the external ring and which has a circular opening (38, 138), the shoulder comprising an annular internal face (48, 148) which is intended to abut the end face (26) of the tube (16) and the transverse end face (22) of the internal ring (12) located at the side of the end of the tube. The invention also relates to the method for assembling such an attachment device and the use thereof in the construction of a dirigible.