Asymmetrical Threaded Bush With Collar for CFRP Holding Power
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Solution Overview
Problem
Existing threaded bushings lack sufficient holding power, particularly when used in composite materials like CFRP, where traditional symmetrical threads are ineffective in providing secure fastening.
Innovation Solution
A threaded bushing design featuring an asymmetrical external thread with a collar that is loaded in the direction of intended stress, allowing the collar to rest against the workpiece edge, enhancing holding power. The bushing includes an internal thread starting from the collar end and an external thread that is self-tapping or self-forming, with a tool using a spring-loaded expanding mechanism for secure installation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a threaded bushing with a collar is used, then the holding power is improved, but the device complexity increases due to the additional collar structure and asymmetrical thread design
Solution Approach 1:
The patent applies asymmetry by designing an asymmetrical thread profile where the thread flanks have different angles relative to the axis of the bushing. This asymmetrical design, combined with the collar positioned at one end, creates a structure that resists tensile loads more effectively by directing forces through the collar and engaged thread flanks, thereby improving holding power while maintaining structural efficiency.
2Stability of the object's composition
If the collar is positioned to rest against the workpiece edge under tensile load, then the connection stability is improved, but the ease of operation decreases due to restricted screw insertion access
Solution Approach 1:
The patent positions the collar at one end of the bushing, creating a dimensional arrangement where the collar engages the workpiece edge in one direction (axial direction) while the asymmetrical thread engages in the rotational dimension. This spatial arrangement allows the collar to provide stable support under tensile load while the asymmetrical thread profile facilitates screw insertion from the opposite end, resolving the conflict between stability and ease of operation.
3Reliability
If an asymmetrical thread is used, then the holding power in composite materials is improved, but the manufacturing precision requirements increase due to the complex thread geometry
Solution Approach 1:
The patent implements asymmetry in the thread profile with different flank angles optimized for engagement in composite materials. The asymmetrical design allows one flank to engage more aggressively with the material while the other provides smoother engagement, improving holding power. The collar position and thread asymmetry work together to distribute loads effectively, reducing the need for extreme manufacturing precision while maintaining high reliability in composite material applications.
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 design significantly increases the holding power of the threaded bushing in composite materials by ensuring the collar is loaded in the direction of stress, preventing twisting during screw insertion and providing a gas-tight connection, thus ensuring secure fastening and preventing material displacement.
Implementation Method 1
a tool using a spring-loaded expanding mechanism for secure installation
Implementation Method 2
an external thread which is designed either as a self-tapping or as a self-tapping thread
Implementation Method 3
the collar of the threaded bushing rests against the edge of the workpiece, which is stressed in compression
Data Source
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AI summary
A threaded bushing has an external thread and an internal thread. At one end, the bushing is provided with an outwardly projecting collar whose outer diameter is larger than the outer diameter of the external thread. The thread is asymmetrical. The bushing is screwed into a bore in a workpiece with its end without the collar first, until the collar on the opposite side comes into contact. The arrangement is such that a tensile load acts on the bushing in such a way that the collar opposes the tensile load.