Polyimide Ring Fastening for Composite Structures
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Solution Overview
Problem
Existing fixing devices for composite material structures in the aeronautical field face issues such as loosening under vibrations, seizing with titanium alloy screws, and limited screwing/unscrewing cycles, particularly due to the constraints of composite materials and the need for minimal overhang, which are not adequately addressed by existing technologies.
Innovation Solution
A fastening device featuring a plastic ring for braking, made of polyimide, which prevents untimely loosening and reduces seizing risks, combined with a tubular insert with longitudinal grooves for adhesive distribution and a tapered threaded screw, allowing multiple screwing/unscrewing cycles without material deformation, and a holding device for secure installation using a deformable material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If titanium alloy screws are used to reduce weight, then weight reduction is achieved, but the risk of seizing and damage to braking devices increases
Solution Approach 1:
A plastic ring made of polyimide is introduced as an intermediary element between the titanium alloy screw and the braking device. This ring prevents direct metal-to-metal contact, eliminating the seizing risk while allowing the lightweight titanium alloy screw to be used. The ring deforms elastically during assembly to accommodate the threaded rod and maintains the connection without seizing.
2Ease of manufacture
If conventional fixing devices are used, then assembly is simple, but loosening under vibrations occurs
Solution Approach 1:
The plastic ring utilizes elastic deformation as a key parameter change mechanism. During assembly, the ring deforms elastically to accommodate the threaded rod, and this elastic property maintains continuous contact pressure between the screw components, preventing loosening under vibrations while keeping the assembly process simple.
3Adaptability or versatility
If multiple screwing/unscrewing cycles are performed, then maintenance is enabled, but material deformation and damage occur
Solution Approach 1:
The plastic ring is designed as a sacrificial, replaceable component that absorbs the wear and deformation from multiple screwing/unscrewing cycles. While the ring may degrade over time, it protects the more valuable titanium alloy screw and braking devices, enabling maintenance cycles without damaging the critical structural components.
4Length of moving object
If minimal overhang is required, then structural compactness is achieved, but the tapered threaded portion cannot protrude
Solution Approach 1:
The tapered threaded portion of the screw is nested within the body of the insert, with the plastic ring positioned inside the insert body. This nested arrangement allows the threaded connection to be formed without the screw protruding beyond the insert, achieving minimal overhang while maintaining assembly feasibility through the elastic deformation of the ring during installation.
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 solution effectively prevents screw loosening, reduces seizing risks, and significantly increases the number of screwing/unscrewing cycles while maintaining structural solidity and minimizing overhang, ensuring reliable and durable fastening in composite material structures.
Implementation Method 1
The ring, when new, has an internal diameter less than a maximum diameter of the threaded rod of the screw... the behavior of said plastic ring when the screw is fitted is difficult to control
Implementation Method 2
the outer surface of the tubular body being bonded to an inner surface of the bore by means of an adhesive
Data Source
Figure 1~2
Figure 3
AI summary
The invention relates to a securing device (10) for a structure (11) provided with an open-ended cylindrical bore (13a), the securing device comprising: - an insert (15) comprising a tapped tubular body (16) and a head (18), the end (20) of the body that is opposite the head having an annular cavity holding a ring (21) made of plastics material; - a screw (22) comprising a cylindrical threaded shank (16) assembled with the thread of the insert and a head (23), the end (30) of the cylindrical threaded shank being frustoconical; the device being characterized in that the threaded shank is introduced into the insert on the ring side such that, in the assembled state, the head of the insert and the head of the screw form terminal ends of the securing device (10). The invention also relates to an assembly for the installation of such a device, and also to an installation method.